Quarterly Report for Quarter Ending September 30, 2025 (Form 10-Q)

MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS.

The following discussion should be read in conjunction with our unaudited condensed consolidated financial statements and notes thereto included in this Quarterly Report on Form 10-Q, and our audited consolidated financial statements and notes thereto for the year ended December 31, 2024 included in our 2024 Form 10-K. This discussion contains forward-looking statements reflecting our current expectations that involve risks and uncertainties. See "Note Regarding Forward-Looking Statements" for a discussion of the uncertainties, risks and assumptions associated with these statements. Our actual results and the timing of events could differ materially from those expressed or implied by the forward-looking statements due to important factors and risks including, but not limited to, those set forth below under "Risk Factors" and elsewhere herein, and those identified under Part I, Item 1A of our 2024 Form 10-K.

Overview

We are a diversified clinical-stage company developing therapeutics designed to treat cancer and related diseases in areas of high unmet need. As a result of the acquisition in March 2022 of Theriva Biologics, S.L. ("VCN", formerly named VCN Biosciences, S.L.), described in more detail below (the "Acquisition"), we transitioned our strategic focus to oncology through the development of VCN's new oncolytic adenovirus platform designed for intravenous and intravitreal delivery to trigger tumor cell death, to improve access of co-administered cancer therapies to the tumor, and to promote a robust and sustained anti-tumor response by the patient's immune system. Our lead product candidate, VCN-01, a clinical stage oncolytic human adenovirus that is modified for tumor-selective replication and to express an enzyme, PH20 hyaluronidase, that has been evaluated in a Phase 2b clinical study for the treatment of pancreatic cancer ("VIRAGE"), and has recently been used to treat patients in a Phase 1 clinical study for the treatment of retinoblastoma, and Phase 1 clinical studies for the treatment of other solid tumors including head and neck squamous cell carcinoma.

Prior to the Acquisition, our focus was on developing therapeutics designed to treat gastrointestinal (GI) diseases which included our clinical development candidates: (1) SYN-004 (ribaxamase) which is designed to degrade certain commonly used intravenous (IV) beta-lactam antibiotics within the GI tract to prevent microbiome damage, thereby preventing overgrowth and infection by pathogenic organisms such as Clostridioides difficile infection (CDI) and vancomycin resistant Enterococci (VRE), and reducing the incidence and severity of acute graft-versus-host-disease (aGVHD) in allogeneic hematopoietic cell transplant (HCT) recipients, and (2) SYN-020, a recombinant oral formulation of the enzyme intestinal alkaline phosphatase (IAP) produced under cGMP conditions and intended to treat both local GI and systemic diseases. As part of our strategic transformation into an oncology focused company, we are exploring value creation options for our SYN-004 and SYN-020 assets, including out-licensing or partnering.

Financial Developments

On June 20, 2025, we filed a prospectus supplement (the "Prospectus Supplement") to our Registration Statement on Form S-3(the "Form S-3"), as amended (File No. 333-279077), which Form S-3 was declared effective by the Securities and Exchange Commission (the "SEC") on September 25, 2024 (the "Registration Statement"), relating to the offer and sale of up to $2,534,352 of shares of our common stock, par value $0.001 per share (the "Common Stock"), from time to time through or directly to A.G.P./Alliance Global Partners (the "Sales Agent") pursuant to the terms of that certain Amended and Restated At Market Issuance Sales Agreement, dated February 9, 2021, as amended by Amendment No. 1 thereto, dated May 3, 2021, as further amended by Amendment No. 2 thereto, dated May 2, 2024 (the "ATM Sales Agreement"). Sales of Common Stock, if any, under the Prospectus Supplement will be made by any method permitted that is deemed an "at the market offering" as defined in Rule 415(a)(4) promulgated under the Securities Act. The Sales Agent is not required to sell any specific amount, but will act as our Sales Agent using commercially reasonable efforts consistent with its normal trading and sales practices. The Sales Agent will be entitled to compensation at a commission rate equal to up to 3.0% of the gross sales price per share of Common Stock sold. During the three and nine months ended September 30, 2025, we sold approximately 706,810, shares of our Common Stock pursuant to the ATM Sales Agreement and received net proceeds of approximately $279,000. During October 2025, we sold approximately 5,016,586 shares of our Common Stock pursuant to the ATM Sales Agreement and received net proceeds of approximately $2.2 million. On October 24, 2025, we filed prospectus supplement no. 2 to the Form S-3, relating to the offer and sale of up to $4,019,597 of shares of our Common Stock pursuant to the ATM Sales Agreement, pursuant to which we have sold 10,326,015 of shares of Common Stock and received net proceeds of approximately $3.9 million as of the date of the filing of this Quarterly Report on Form 10-Q.

On September 28, 2025, the Board of Directors approved a plan to resize and restructure the company for purposes of focusing its attention on business development and licensing activities, clinical trial planning, exploratory VCN-01 manufacturing scale-up, limited preclinical activities related to VCN-01 and VCN-12 (the first candidate from our VCN-X discovery program), and our upcoming interactions with the U.S. Food and Drug Administration and the European Medicines Agency for proposed pivotal clinical trials of VCN-01 in patients with mPDAC and retinoblastoma (the "Plan"). Pursuant to the Plan, on September 30, 2025, we implemented a workforce reduction of approximately seven employees or 32% of the current global Company workforce. The goal of this reduction is to direct our resources towards the activities detailed above in the Plan, which it believes will represent its best opportunity for success. We expect to substantially complete the employee reduction immediately and estimate that it will incur a total of approximately $520,000 in charges in connection with the workforce reduction, which was accrued for as of September 30, 2025. These charges consist primarily of cash severance and benefits over a three-month period, in connection with the workforce reduction. The Plan is expected to save approximately $1.8 million in compensation and benefits annually, and together with additional anticipated operating cost reductions and capital raised pursuant to the ATM Sales Agreement, we expect that it will extend our cash runway into the first quarter of 2027.

On October 16, 2025, we entered into a warrant inducement agreement (the "Inducement Agreement") with certain holders named therein (the "Holders") of existing Common Stock Purchase Warrants to purchase up to an aggregate of 8,092,280 shares of Common Stock, consisting of (i) Common Stock Purchase Warrants to purchase up to an aggregate of 1,345,000 shares of Common Stock issued on September 27, 2024 (the "September Warrants") and (ii) Common Stock Purchase Warrants to purchase up to an aggregate of 6,747,280 shares of Common Stock issued on May 8, 2025 (the "May Warrants" and, together with the September Warrants, the "Existing Warrants"). Pursuant to the Inducement Agreement, on October 17, 2025, the Holders exercised for cash the Existing Warrants at a reduced exercise price of $0.54 per share and, in consideration therefor, we issued to the Holders new Common Stock Purchase Warrants (the "New Warrants") to purchase an aggregate of 16,184,560 shares of Common Stock, equal to 200% of the number of shares of Common Stock underlying the Existing Warrants, at an exercise price of $0.54 per share, which New Warrants are exercisable for a term of five (5) years from the date of the approval from our stockholders of the full exercise of the New Warrants and the issuance of all of the shares of Common Stock issuable upon the exercise thereof.

We received aggregate gross proceeds of approximately $4.4 million for the exercise of the Existing Warrants, before deducting placement agent fees and other expenses payable by us. We expect to use the net proceeds from the Warrant Exercise for working capital. AGP served as our exclusive financial advisor in connection with the warrant exercise and other transactions described in the Inducement Agreement. Pursuant to the terms of an engagement letter, dated October 16, 2025, by and between us and AGP, we agreed to pay to AGP a cash fee equal to 7.0% of the aggregate gross proceeds received from the Holders upon exercise of the Existing Warrants and reimbursement of certain expenses.

On August 29, 2025, we held our 2025 Annual Meeting of Stockholders (the "Annual Meeting"). At the Annual Meeting, our stockholders (i) elected Jeffrey J. Kraws, John Monahan, Steven A. Shallcross and Jeffery Wolf as directors; (ii) ratified the appointment of BDO USA P.C. as our independent registered public accounting firm for the year ending December 31, 2025; (iii) approved an amendment ("Amendment No. 2") to our 2020 Stock Incentive Plan (the "2020 Stock Incentive Plan") to (a) increase the number of shares of Common Stock that we will have authority to grant under the 2020 Stock Incentive Plan from 2,500,000 shares of Common Stock to 4,500,000 shares of Common Stock and (iii) approved, on an advisory basis, the compensation of our named executive officers.

Our Current Product Pipeline

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*Based on management's current beliefs and expectations

aGVHD acute graft-versus host disease. allo-HCT allogeneic hematopoietic cell transplant. CSR clinical study report. HNSCC head and neck squamous cell carcinoma. IV intravenous. IVit intravitreal. For other abbreviations see the text.

¹Additional products with preclinical proof-of-concept include SYN-006 (carbapenemase) to prevent aGVHD, CDI, and microbiome damage in patients treated with carbapenem antibiotics and SYN-007 (ribaxamase) DR to prevent antibiotic associated diarrhea with oral β-lactam antibiotics.

²Depending on funding/partnership. SYN-004 may enter a U.S. Food and Drug Administration ("FDA")-agreed Phase 3 clinical trial for the treatment of CDI.

Recent Clinical Developments

On October 8, 2025, preclinical data for VCN-12, a next generation oncolytic adenovirus developed as part of the VCN-X discovery program, was presented by Dr. Ramon Alemany at the 32^nd Annual Congress of the European Society of Gene & Cell Therapy. VCN-12 uses the same virus capsid as our lead clinical candidate VCN-01 (zabilugene almadenorepvec), but includes modifications intended to (i) increase stroma degradation by replacing human hyaluronidase PH20 with the more active bee hyaluronidase; and (ii) increase tumor cell lysis by expressing the pore forming protein parasporin-2 to enable both cytotoxic and immunogenic cell death. Parasporin-2 expression is expected to destroy both infected and surrounding uninfected tumor cells and stimulate a strong overall antitumor immune response and reduce viral immunodominance. Data presented by Dr. Alemany support the proposed VCN-12 mechanisms of action. VCN-12 showed increased cell killing compared to VCN-01 in a variety of cancer cell models in vitro. VCN-12 also displayed higher levels of hyaluronidase activity. In animal studies, intravenous VCN-12 had a similar toxicity profile to VCN-01 in immunodeficient mice bearing human tumor xenografts. Intratumoral VCN-12 significantly reduced tumor growth compared to VCN-01 in immunocompetent hamsters bearing HP-1 pancreatic tumors. The antitumor effect of VCN-12 was observed in both the injected tumors and second tumors-implanted 4-days later but not injected. Complete tumor regression of the first tumor was observed in two of nine hamsters and the second implanted tumor did not grow in these animals. VCN-12 appeared to stimulate a persistent immune response that prevented the establishment of tumors in these two complete responders when they were implanted with HP-1 cells 43 days after VCN-12 treatment. Further preclinical studies are planned to elaborate these initial findings. In addition to the scheduled presentation on VCN-12, a recently-published pre-ESGCT meeting monograph details the results of a preclinical study conducted by investigators at the University of Navarra evaluating the intracranial administration of VCN-01 for the potential treatment of brain tumors. The authors highlight the urgent need to develop new and improved therapies for brain cancers and conclude that their findings "provide a strong rationale for its [VCN-01] further development as a therapeutic option for patients with brain tumors" (Palacios-Alonso D et al. (2025) Toxicity and Biodistribution of the Oncolytic Virus VCN-01 Following Intracranial Injection in Syrian Hamsters. Hum Gene Ther. 36(17-18):1237-1247. (doi: 10.1177/10430342251372091).

On October 20, 2025, expanded mPDAC data from the VIRAGE Phase 2b trial (NCT05673811) was presented at the European Society for Medical Oncology (ESMO 2025) Annual Congress. An abstract separate poster presentation on the same day describing previously reported data for SYN-004 (ribaxamase) in allogeneic hematopoietic transplant recipients was presented at Infectious Diseases Week (IDWeek) 2025 Annual Meeting. Results from the VIRAGE Phase 2b trial included in the abstract for the presentation titled "VIRAGE trial: randomized Phase IIb, open-label, study of Nab-Paclitaxel and Gemcitabine with/without intravenous VCN-01 in Patients with Metastatic Pancreatic Cancer (mPDAC )" are set forth below:

112 patients were randomized. Patients in the modified intent to treat (mITT) population received at least 1 dose of gemcitabine/nab-paclitaxel (GA) standard of care chemotherapy (GA, Arm I) or VCN-01 (Arm II). Patients in the full analysis set (FAS) population received at least 1 dose of gemcitabine/nab-paclitaxel standard of care chemotherapy (GA; Arm I) or VCN-01 followed by at least 1 dose of GA (Arm II).

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Compared to patients who started GA cycle 4 alone (Arm I), patients who received 2 VCN-01 doses and started GA cycle 4 (Arm II) showed greater improvement in OS (14.8 vs 11.6 months; HR 0.44; 95% CI 0.21 - 0.92; P=0.046) and PFS (11.2 vs 7.4 months; HR 0.48; 95% CI 0.25 - 0.91; P=0.017). VCN-01 administration was well tolerated. All VCN- 01-related serious adverse events (n=13) were resolved, the most common being flu-like symptoms (13,2%), transaminase increase (5.7%) and drug-induced liver injury (3.8%). Viral genome analysis confirmed the bioactivity of the second VCN-01 dose.

This study met its primary endpoints. Patients receiving VCN-01 + GA had improved OS, PFS and DoR compared to GA standard of care.

Our Current Oncology-Focused Pipeline

Oncolytic Viruses

Our oncology platform is based on oncolytic virotherapy ("OV therapy"), which exploits the ability of certain viruses to kill tumor cells and trigger an anti-tumor immune response. This novel class of anticancer agents has unique mechanisms of action compared to other cancer drugs. Oncolytic viruses ("OV") exploit the fact that cancer cells contain mutations that cause them to lose growth control and form tumors. Once inside a tumor cell, oncolytic viruses exploit the tumor cell machinery to generate thousands of additional copies of the virus, which then kill the tumor cell and spread to neighboring cells, causing a chain reaction of cell killing. This infection and tumor cell killing by OVs also alerts the immune system, which can then attack the virus infected tumor cells to help destroy the tumor in some instances.

Our OV product candidates are engineered to efficiently infect and selectively replicate to a high extent in tumor cells versus normal host cells, which enables intravenous delivery. By contrast, many other OVs in clinical development today are administered by direct injection into the tumor. Intravenous delivery has the potential to expand the therapeutic effect of OVs because the virus can infect both the primary tumor and tumor metastases throughout the body.

Our first product candidate VCN-01, is a clinical stage oncolytic human adenovirus that is modified to express an enzyme, PH20 hyaluronidase, that is designed to degrade hyaluronan in the tumor stroma, which helps the virus and other molecules to penetrate and spread throughout the tumor. VCN-01 can be used alone or in combination with other cancer therapies, such as chemotherapy and

immunotherapy, for difficult to treat cancers. An expanding intellectual property portfolio supports our oncology programs, and because our products are characterized as biologics with Orphan Drug designation in our target indications, if approved by the FDA they will be further protected by data and/or market exclusivity.

VCN-01 has been administered to 142 patients across multiple Phase 1 clinical trials and the Phase 2b VIRAGE trial, including patients with pancreatic cancer, head and neck squamous cell carcinoma, ovarian carcinoma, colorectal cancer, and retinoblastoma.

Current clinical update

We have recently completed patient treatment and follow-up in a Phase 2b clinical trial of intravenous VCN-01 with nab-paclitaxel plus gemcitabine in patients with mPDAC and the clinical study report (CSR) has been completed. Similarly, CSRs have been completed for the Phase 1 investigator sponsored trials evaluating (i) intravitreal VCN-01 in patients with retinoblastoma; and (ii) intravenous VCN-01 in combination with durvalumab in subjects with recurrent/ metastatic squamous cell carcinoma of the head and neck (mSCCHN). A protocol amendment has been submitted in an additional investigator sponsored Phase 1 trial evaluating the intravenous administration of VCN-01 in patients prior to surgical resection of high-grade brain tumors and on July 8, 2025 we were notified by the investigator that the protocol amendment had been approved by the Medicines and Healthcare products Regulatory Agency (MHRA) from UK.

Phase 1 Clinical Trials in PDAC

The safety, tolerability, and potential dosing regimens for VCN-01 in patients with PDAC or colorectal cancer were evaluated in Phase 1 clinical trials evaluating intratumoral (n=8; NCT02045589) and intravenous (n= 42; NCT02045602) VCN-01 either alone or in combination with gemcitabine ± nab-paclitaxel (published in J. Immunother. Cancer 2021 Nov;9(11):e003254 and J. Immunother. Cancer 2022 Mar;10(3):e003255, respectively). Intravenous VCN-01 was found to have an acceptable tolerability profile in PDAC and colorectal cancer patients and demonstrated compelling biochemical and clinical outcomes that enabled the advancement of VCN-01 into the Phase 2 clinical trial in patients with metastatic PDAC.

Phase 2 Trial of intravenous VCN-01 with nab-paclitaxel plus gemcitabine in patients with PDAC

In January 2023, we dosed the first patients in VIRAGE, the Phase 2b randomized, open-label, multicenter clinical trial of systemically administered VCN-01 in combination with standard-of-care (SoC) chemotherapy (gemcitabine/nab-paclitaxel) as a first line therapy for patients with newly-diagnosed metastatic pancreatic ductal adenocarcinoma. The study is being conducted at approximately 17 sites in the US and EU. Two doses of VCN-01 are included in the treatment arm: the 1st dose is administered on day 1, then one week later 3 cycles of gemcitabine and nab-paclitaxel as standard of care is administered. The second VCN-01 dose is administered 7 days before the 4th cycle of chemotherapy (approximately 90 days after the first VCN-01 dose), followed by additional cycles of gemcitabine/nab-paclitaxel chemotherapy.

Patient dosing was initiated in the U.S. in July 2023 and on September 23, 2024, we announced that we achieved our target patient enrollment of 92 evaluable patients in the VIRAGE Phase 2b clinical trial. Thirty - six patients received their second doses of intravenous VCN-01, which were well tolerated and demonstrated the expected VCN-01 adverse event profile. Topline data for the VIRAGE Phase 2b clinical trial was announced Q2 2025.

On January 30, 2024, the accumulated clinical data from patients enrolled across 6 sites open in the U.S. and 9 sites open in Spain were reviewed by an Independent Data Monitoring Committee (IDMC). According to the IDMC's assessment, the ongoing Phase 2b trial continued without any changes to the protocol. No safety concerns were raised based on the evaluation of data presented at the IDMC meeting. Intravenous VCN-01 has been well tolerated and demonstrated a safety profile consistent with prior clinical trials. Importantly, no additional toxicities were observed in patients receiving a second dose of VCN-01, providing the first clinical evidence of the feasibility of repeated systemic dosing.

On May 10, 2024, we presented data demonstrating enhanced anti-tumor effects in human pancreatic cancer xenograft-bearing mice treated with lead product candidate VCN-01 and liposomal irinotecan. These data support the potential synergy of VCN-01 and first-line pancreatic cancer chemotherapy regimens.

On May 23, 2024, we announced that the FDA granted Fast Track Designation (FTD) to lead clinical candidate VCN-01 in combination with gemcitabine and nab-paclitaxel to improve progression-free survival and overall survival in patients with metastatic pancreatic adenocarcinoma.

On June 1, 2024, we presented the design of VIRAGE trial in a poster at the American Society of Clinical Oncology (ASCO) Annual Meeting 2024 Congress held and in Chicago (Illinois) from May 31- June 4, 2024. The poster discussed the objectives, endpoints and key inclusion and exclusion criteria included in the trial protocol, together with the treatment schedule for each arm of the study.

On December 5, 2024 we announced the outcomes of a Type D meeting with the FDA to obtain guidance on the design of a potential Phase 3 clinical study of VCN-01 in combination with standard-of-care chemotherapy for the treatment of mPDAC. FDA advised that the optimal path forward for the VCN-01 PDAC program is to conduct a stand-alone Phase 3 study of VCN-01 with gemcitabine/nab-paclitaxel. The FDA provided general agreement with our proposed design for a Phase 3 clinical study and indicated that inclusion of additional standard-of-care chemotherapy for mPDAC was not necessary as it would complicate the study design and analysis. The FDA meeting also highlighted the FDA's preferences regarding certain statistical elements of confirmatory clinical studies, including methods for sample size estimation and the study population(s) used for data analysis.

On February 4, 2025, we received Scientific Advice from the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) on the design of a potential Phase 3 clinical study of VCN-01 in combination with standard-of-care chemotherapy for the treatment of mPDAC. Consistent with feedback from the FDA, CHMP advised that a marketing authorization application (MAA) for VCN-01 in mPDAC could be supported by positive results from a randomized, controlled, stand-alone Phase 3 study comparing VCN-01 combined with gemcitabine/nab-paclitaxel to gemcitabine/nab-paclitaxel standard-of-care alone. The Scientific Advice also included CHMP suggestions regarding the study populations, inclusion/exclusion criteria, randomization and blinding, priority endpoints, and proposed statistical strategies for data analysis. An additional comment from the EMA Committee for Orphan Medicinal Products (COMP) noted that the potential benefit of VCN-01 with gemcitabine/nab-paclitaxel in a Phase 3 trial will be compared with the therapeutic effects of the other approved standard-of-care chemotherapies (FOLFIRINOX, NALIRIFOX) when considering maintenance of the Orphan Medicinal Product status of VCN-01 at the time of an MAA.

On March 31, 2025, we announced that a second Independent Data Monitoring Committee (IDMC) review of data from the VIRAGE Phase 2b clinical trial in newly-diagnosed mPDAC found that VCN-01 was well tolerated in combination with standard-of-care chemotherapy (gemcitabine/nab-paclitaxel) and the adverse event (AE) profile was as expected for the patient population and the medications being studied. The VCN-01 AE profile was consistent with that observed in prior clinical trials. The most common VCN-01 related AEs (pyrexia, flu-like illness, vomiting, nausea, and elevated transaminases) were transient and reversible. These AEs were observed to be less frequent and of reduced CTCAE grade after the second VCN-01 dose (administered on day 92) compared to the first VCN-01 dose (administered on day 1). The IDMC noted that the overall type and number of AEs in the VCN-01 treatment group was as expected for the pancreatic cancer population, the duration of treatment, and the administration of an oncolytic virus.

On May 7, 2025, we announced positive topline outcomes from the VIRAGE Phase 2b clinical trial evaluating our lead product candidate VCN-01 (zabilugene almadenorepvec) plus standard-of-care (SoC) chemotherapy gemcitabine/nab-paclitaxel as a first line therapy for patients with mPDAC for whom gemcitabine/nab-paclitaxel is the recommended first-line treatment option. Topline outcomes are detailed above under "Recent Clinical Developments".

On October 20, 2025, expanded mPDAC data from the VIRAGE Phase 2b trial (NCT05673811) were presented at ESMO 2025.

Retinoblastoma

Phase 1 Trial of intravitreal VCN-01 in patients with retinoblastoma

During the third quarter of 2017, VCN entered into a Clinical Trial Agreement with Hospital Sant Joan de Déu (Barcelona, Spain) to conduct an investigator sponsored Phase 1 clinical study evaluating the safety and tolerability of two intravitreal injections of VCN-01 in patients with intraocular retinoblastoma refractory to systemic, intra-arterial or intravitreal chemotherapy, or radiotherapy, in whom enucleation was the only recommended treatment (NCT03284268). Patients received two intravitreal injections of VCN-01, 14 days apart, at a dose of either 2 x 10⁹ vp/eye (n=1) or 2 x 10¹⁰ vp/eye (n=8). The clinical database for the study has now been locked and the clinical study report is being prepared.

On April 23, 2024, we announced positive topline data from this study, with agreement by the study Monitoring Committee that the study had a positive outcome. Per the terms of the clinical trial agreement, the determination by the study Monitoring Committee that the study had a positive outcome means we received an exclusive, worldwide technology license, and related patents from Hospital Sant Joan de Déu for the treatment of pediatric patients with advanced retinoblastoma and we will pay to Hospital Sant Joan de Déu the

amount of three hundred twenty thousand, two hundred and sixty five Euros (€320,265) or approximately $334,000, upon receipt by us of the final clinical study report.

A pre-Investigational New Drug ("IND") meeting with the FDA was held on December 19, 2023 to discuss the path forward for VCN-01 as an adjunct to chemotherapy in pediatric patients with advanced retinoblastoma. The FDA provided some guidance on the potential endpoints and patient population for an advanced clinical trial and encouraged submission of a formal protocol under a US IND in order to provide more detailed commentary.

On July 30, 2024, we received notice from the FDA that we had been granted Rare Pediatric Drug Designation (RPDD) for VCN-01 for the treatment of retinoblastoma. The FDA grants RPDD for rare diseases (fewer than 200,000 affected persons in the United States) that are serious and life-threatening and primarily affect children ages 18 years or younger. If a Biologics License Application for VCN-01 for the treatment of retinoblastoma is approved by the FDA by September 30, 2026, we may be eligible to receive a Priority Review Voucher. Previously, the FDA granted orphan drug designation to VCN-01 for treatment of retinoblastoma.

On October 11, 2024, the European Commission adopted the European Medicines Agency (EMA) recommendation to grant Orphan Medicinal Product Designation to VCN-01 for the treatment of retinoblastoma.

On May 27, 2025, we announced the presentation of the final data from an investigator-sponsored Phase 1 study of VCN-01 (zabilugene almadenorepvec) in refractory retinoblastoma patients in a poster presented by Dr. Jaume Català-Mora, Pediatric Ophthalmologist, Sant Joan de Déu-Barcelona Children's Hospital at the 2025 American Society of Clinical Oncology (ASCO) annual meeting. Topline outcomes are detailed above under "Recent Clinical Developments" section.

Phase 1 Trial of intravenous VCN-01 in Combination with Durvalumab in Subjects with Recurrent/ Metastatic SCCHN

In February 2019, VCN entered into a Clinical Trial Agreement with Catalan Institute of Oncology (ICO) (Spain) to conduct an investigator sponsored Phase 1 clinical study to evaluate the safety, tolerability and RP2D of a single intravenous injection of VCN-01 combined with durvalumab in two administration regimens: VCN-01 concomitantly with durvalumab, or sequentially with durvalumab starting two weeks after VCN-01 administration (NCT03799744). The study is also designed to evaluate whether VCN-01 treatment can re-sensitize PD-(l)-1 refractory tumors to subsequent anti-PD-L1 therapy. Durvalumab is a human monoclonal antibody (mAb) of the immunoglobulin G (IgG) 1 kappa subclass that inhibits binding of PD-L1. It is marketed as IMFINZI® by AstraZeneca/MedImmune, who supplied the product for its use in the clinical study. This Phase I trial is a multicenter, open label, dose escalation study in patients with histologically confirmed head and neck squamous cell carcinoma from specific sites: oral cavity, oropharynx, larynx or hypopharynx that is recurrent/metastatic (R/M) and not amenable to curative therapy by surgery or radiation. In addition, all patients should have undergone prior exposure to anti-PD-(L) 1 and progressed. Patients are entered at each dose level, according to a planned dose escalation schedule. The treatment is a single intravenous VCN-01 dose combined with concomitant intravenous durvalumab (MEDI4736) 1500 mg Q4W (Arm I) or durvalumab starting two weeks after VCN-01 administration ("sequential schedule"; Arm II). Patient recruitment into Arm I and Arm II was performed concurrently. Intravenous VCN-01 was administered to each patient only once during the trial at the VCN-01 dose level to which they were randomized. Durvalumab was administered Q4W until disease progression, unacceptable toxicity, withdrawal of consent, or another discontinuation criterion. Patient recruitment into the study was completed in February 2022 with a total of 18 patients enrolled. On September 5, 2022 we announced a presentation of initial data from this study in a poster at the European Society for Medical Oncology (ESMO) Congress. The poster reported that treatment with VCN-01 was well tolerated when administered with durvalumab in the sequential schedule and the most common treatment-related adverse events were dose-dependent and reversible pyrexia, flu-like symptoms and increases in liver transaminases. Sustained blood levels of VCN-01 viral genomes and increased serum hyaluronidase levels were maintained for over six weeks and analysis of tumor samples showed an increase in CD8 T cells (a marker of tumor inflammation); upregulation of PD-L1; and downregulation of matrix-related pathways after VCN-01 administration. The study has been completed and the clinical study report has been completed.

On October 16, 2023, we presented additional data from this study in a poster at the European Society for Medical Oncology (ESMO) 2023 Congress held virtually and in Madrid, Spain from October 20-24, 2023. Key data and conclusions featured in the ESMO presentation include:

Phase 1 Trial evaluating the safety and feasibility of huCART-meso cells when given in combination with VCN-01

In July 2021, VCN entered into a Clinical Trial Agreement with the University of Pennsylvania (Philadelphia) to conduct an investigator sponsored Phase 1 clinical study to evaluate the safety, tolerability and feasibility of intravenous administration of VCN-01 in combination with lentiviral transduced huCART-meso cells (developed by the laboratory of Dr. Carl June) in patients with histologically confirmed unresectable or metastatic pancreatic adenocarcinoma and serous epithelial ovarian cancer (NCT05057715). This is a Phase I study evaluating the combination of VCN-01 when given in combination with huCART-meso cells in a dose-escalation design in two cohorts (N = 3-6), where patients receive VCN-01 as a single IV infusion (at 3.3x10¹² or 1x10¹³ vp) on Day 0, followed by a single dose of 5x10⁷ huCART-meso cells on Day 14 via IV infusion. huCART-meso cells are modified T-cells targeting the mesothelin antigen, which is frequently expressed in multiple tumor types, particularly in pancreatic and ovarian cancers. Dr. June's previous clinical studies have shown that huCART-meso cells encounter significant challenges in the tumor microenvironment, including immunosuppressive cells and soluble factors as well as metabolic restrictions. Initial VCN-01 clinical data from the studies described above suggest that administration of VCN-01 may increase tumor immunogenicity and improve access of the huCART-meso cells to tumor cells. This Phase I study will evaluate the safety and tolerability of the VCN-01 huCART-meso cell combination and test the hypothesis that administration of VCN-01 may enhance the potential antitumor effects of the co-administered huCART-meso cells.

On July 8, 2022, we were notified that the first patient to be dosed with VCN-01 had passed the safety evaluation period in this study. On June 22, 2023, at their Cellicon Valley conference, and again at the Society for Immunotherapy of Cancer (SITC) meeting in San Diego, CA on November 3, 2023, and the International Oncolytic Virotherapy Conference (IOVC2023) in Calgary on November 13 2023, University of Pennsylvania investigators presented preliminary clinical safety and pharmacokinetic data from this study highlighting the feasibility of administering VCN-01 in sequence with huCART-meso cells in pancreatic and ovarian cancer patients. VCN-01 persistence was suggestive of tumor infection and active replication. The peak and duration of huCART-meso T cells in the peripheral blood as well as duration of stable disease in evaluable patients showed encouraging trends.

On October 16, 2024, at the 2024 Advancing Gene Therapy and Cell Therapies for Cancer conference by the American Society for Gene and Cell Therapy in Philadelphia, University of Pennsylvania investigators presented results from the Phase 1 trial of huCART-meso cells administered in combination with VCN-01 in patients with pancreatic and serous epithelial ovarian cancer. Safety was in line with expectations from monotherapy studies and 3.3x10¹² was defined as the dose for further development. The C_max of huCART-meso cells showed some signs of enhancement in patients previously infused with VCN-01. 66.6% (4 out of 6) patients with measurable disease receiving huCART-meso after VCN-01 showed tumor shrinkage, indicating a promising trend in disease stabilization in patients receiving huCART-meso and VCN-01 compared to either agent alone.

On November 19, 2024 we were notified by the investigators that they would not continue with the present clinical trial, instead preferring to focus on advancement of a next-generation mesothelin-specific CAR-T. This new CAR-T could potentially be evaluated in combination with VCN-01 in a future clinical trial.

Phase 1 Trial evaluating the intravenous administration of VCN-01 in patients prior to surgical resection of high-grade brain tumors

In the second quarter of 2021, VCN entered into a Clinical Trial Agreement with the University of Leeds (UK) to sponsor a proof-of-concept Phase 1 clinical study to evaluate whether intravenously administered VCN-01 can cross the blood-brain barrier and infect the target brain tumor. This is an open-label, non-randomized, single center study of VCN-01 given intravenously at a dose of 1x10¹³ virus particles to patients prior to planned surgery for recurrent high-grade primary or metastatic brain tumors. We believe that the intravenous delivery of anti-cancer therapy to brain tumors, if effective, may enable the treatment of systemically disseminated brain metastases and may allow for reduction in the need to use neurosurgery to administer the drugs. This study aims to assess the presence of VCN-01 within the resected surgical specimen after systemic VCN-01 delivery and determine the safety of intravenous VCN-01 in patients with recurrent high-grade glioma or brain metastases. By confirming the presence of VCN-01 in high grade brain tumors following intravenous delivery, this study may pave the way for larger trials to study VCN-01 efficacy, both as a monotherapy and in combination with PD-1/PD-L1 blockade. This trial has already received approval from Medicines & Healthcare Products Regulatory Agency (MHRA) from UK Government.

On January 9, 2023, we issued a press release announcing that the first patient was dosed in this study and recruitment is on-going.

On May 12, 2025, a protocol amendment was submitted for this trial to MHRA (UK Regulatory Authorities) and on July 8, 2025 we were notified by the investigator that the protocol amendment had been approved.

Our Current Gastrointestinal (GI) and Microbiome-Focused Pipeline

Our SYN-004 (ribaxamase) and SYN-020 clinical programs are focused on the gastrointestinal tract (GI) and the gut microbiome, which is home to billions of microbial species and composed of a natural balance of both "good" beneficial species and potentially "bad" pathogenic species. When the natural balance or normal function of these microbial species is disrupted, a person's health can be compromised. All of our programs are supported by our growing intellectual property portfolio. We are maintaining and building our patent portfolio through filing new patent applications; prosecuting existing applications; and licensing and acquiring new patents and patent applications.

SYN-004 (ribaxamase) - Prevention of antibiotic-mediated microbiome damage, thereby preventing overgrowth and infection by pathogenic organisms such as Clostridioides difficile infection (CDI) and vancomycin resistant Enterococci (VRE), and reducing the incidence and severity of acute graft-versus-host disease (aGVHD) in allogeneic HCT recipients

SYN-004 (ribaxamase) is a proprietary oral capsule prophylactic therapy designed to degrade certain IV beta-lactam antibiotics excreted into the GI tract and thereby maintain the natural balance of the gut microbiome. Preventing beta-lactam damage to the gut microbiome has a range of potential therapeutic outcomes, including prevention of CDI, suppression of the overgrowth of pathogenic species (particularly antimicrobial-resistant organisms) and potentially reducing the incidence and/or severity of aGVHD in allogeneic hematopoietic cell transplant (HCT) patients. SYN-004 (ribaxamase) 75 mg capsules are intended to be administered orally while patients are administered certain IV beta-lactam antibiotics. The capsule dosage form is designed to release the SYN-004 (ribaxamase) enzyme into proximal small intestine, where it has been shown to degrade beta-lactam antibiotics in the GI tract without altering systemic antibiotic levels. Beta-lactam antibiotics are a mainstay in hospital infection management and include the commonly used penicillin and cephalosporin classes of antibiotics.

Clostridioides difficile Infection

Clostridioides difficile (formerly known as Clostridium difficile and often called C. difficile or CDI) is a leading type of hospital acquired infection and is frequently associated with IV beta-lactam antibiotic treatment. The Centers for Disease Control and Prevention (CDC) identified C. difficile as an "urgent public health threat," particularly given its resistance to many drugs used to treat other infections. CDI is a major unintended risk associated with the prophylactic or therapeutic use of IV antibiotics, which may adversely alter the natural balance of microflora that normally protect the GI tract, leading to C. difficile overgrowth and infection. Other risk factors for CDI include hospitalization, prolonged length of stay (estimated at 7 days), underlying illness, and immune-compromising conditions including the administration of chemotherapy and advanced age.

Phase 1b/2a Clinical Study in Allogeneic HCT Recipients

In August 2019, we entered into a Clinical Trial Agreement (CTA) with the Washington University School of Medicine (Washington University) to conduct a Phase 1b/2a clinical trial of SYN-004 (ribaxamase). Under the terms of this agreement, we serve as the sponsor of the study and supply SYN-004 (ribaxamase). Dr. Erik R. Dubberke, Professor of Medicine and Clinical Director, Transplant Infectious Diseases at Washington University and a member of the SYN-004 (ribaxamase) steering committee serves as the principal investigator of the clinical trial in collaboration with his Washington University colleague Dr. Mark A. Schroeder, Associate Professor of Medicine, Division of Oncology, Bone Marrow Transplantation and Leukemia.

The Phase 1b/2a clinical trial was a single center, randomized, double-blinded, placebo-controlled clinical trial of oral SYN-004 (ribaxamase) in up to 36 evaluable adult allogeneic HCT recipients. The goal of this study is to evaluate the safety, tolerability and potential absorption into the systemic circulation (if any) of oral SYN-004 (ribaxamase; 150 mg four times daily) administered to allogeneic HCT recipients who receive an IV carbapenem or beta-lactam antibiotic to treat fever. Study participants were enrolled into three sequential cohorts administered a different study-assigned IV antibiotic. Each cohort seeks to complete eight evaluable participants treated with SYN-004 (ribaxamase) and four evaluable participants treated with placebo. Safety and pharmacokinetic data for each cohort will be reviewed by an independent Data and Safety Monitoring Committee, which will make a recommendation on whether to proceed to the next IV antibiotic cohort. The study will also evaluate potential protective effects of SYN-004 on the gut microbiome as well as generate preliminary information on potential therapeutic benefits and patient outcomes of SYN-004 in allogeneic HCT recipients.

To date, we have completed 2 of 3 cohorts (Cohorts 1 and 2) in this study. On September 27, 2022, we issued a press release announcing positive outcomes from the Data and Safety Monitoring Committee ("DSMC") review of results from the first Cohort and their recommendation that the study may proceed to enroll Cohort 2 in which study drug (SYN-004 or Placebo) is administered in combination with the IV beta-lactam antibiotic piperacillin/tazobactam.

On February 16, 2023 and April 13, 2023, we announced the presentation of safety and pharmacokinetic data from Cohort 1 of the Phase 1b/2a Clinical Trial of SYN-004 (ribaxamase) in allogeneic hematopoietic cell transplant recipients at the 2023 Tandem Meetings: Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR and at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID), respectively.

On October 3, 2024, we announced a positive outcome from the DSMC review of results from the second Cohort of our Phase 1b/2a randomized, double - blinded, placebo - controlled clinical trial of SYN - 004 (ribaxamase) in allogeneic hematopoietic cell transplant ("HCT") recipients for the prevention of acute graft - versus - host - disease. Based on a review of the safety and pharmacokinetic data, the DSMC recommended that the study may proceed to enroll Cohort 3 in which study drug (SYN - 004 or Placebo) will be administered in combination with the IV beta - lactam antibiotic cefepime. Based upon our current available funding and our focus on our clinical development of VCN - 01 we do not anticipate that enrollment for the third cohort will commence unless we obtain grant funding, or find a licensee or partner to fund the SYN - 004 development program.

On April 10, 2025, we announced the presentation of the previously disclosed blinded safety and pharmacokinetic (PK) data from the ongoing Phase 1b/2a randomized, double - blinded, placebo - controlled clinical trial of SYN - 004 (ribaxamase) in allogeneic hematopoietic cell transplant (HCT) recipients for the prevention of acute graft - versus - host - disease (aGVHD) at the Congress of the European Society of
 Clinical Microbiology and Infectious Diseases (ESCMID Global), taking place in Vienna, Austria from April 11 - 15, 2025. This data was featured in an ePoster Flash Session oral presentation.

SYN-020 - Oral Intestinal Alkaline Phosphatase (IAP)

SYN-020 is a quality-controlled, recombinant version of bovine Intestinal Alkaline Phosphatase (IAP) produced under cGMP conditions and formulated for oral delivery. The published literature indicates that IAP functions to diminish GI and systemic inflammation, tighten the gut barrier to diminish "leaky gut," diminish fat absorption, and promote a healthy microbiome. Despite its broad therapeutic potential, a key hurdle to commercialization has been the high cost of IAP manufacture which is commercially available for as much as $10,000 per gram. We believe we have developed technologies to traverse this hurdle and now have the ability to produce more than 3 grams per liter of SYN-020 and anticipate a cost of roughly a few hundred dollars per gram at commercial scale. Based on the known mechanisms as well as our own supporting animal model data, we intended to initially develop SYN-020 to mitigate the intestinal damage caused by radiation therapy that is routinely used to treat pelvic cancers. While we believe SYN-020 may play a pivotal role in addressing acute and long-term complications associated with radiation exposure to the GI tract, we have also begun planning for

potential development of SYN-020 in large market indications with significant unmet medical needs. Such indications include celiac disease, non-alcoholic fatty liver disease ("NAFLD"), and indications to treat and prevent metabolic and inflammatory disorders associated with aging.

On June 30, 2020, we submitted an IND application to the FDA in support of an initial indication for the treatment of radiation enteropathy secondary to pelvic cancer therapy. On July 30, 2020, we announced that we received a study-may-proceed letter from the FDA to conduct a Phase 1a single-ascending-dose ("SAD") study in healthy volunteers designed to evaluate SYN-020 for safety, tolerability and pharmacokinetic parameters (NCT04815993). On June 29, 2021, we announced that enrollment, patient dosing and observation had been completed in the Phase 1, open-label, SAD study of SYN-020. The SAD study enrolled 6 healthy adult volunteers into each of four cohorts with SYN-020 given orally as single doses ranging from 5 mg to 150 mg. The data demonstrated that SYN-020 maintained a favorable safety profile, was well tolerated at all dose levels, and no adverse events were attributed to the study drug. No serious adverse events were reported.

During the third quarter of 2021 we initiated a Phase 1 clinical study evaluating multiple ascending doses ("MAD") of SYN-020 (NCT05045833). The placebo-controlled, blinded study enrolled 32 healthy adult volunteers into four cohorts with SYN-020 administered orally in doses ranging from 5 mg to 75 mg twice daily for 14 days with a follow-up evaluation at day 35. Each cohort included six subjects who received SYN-020 and two who received placebo. On May 10, 2022, we announced positive safety data from the Phase 1 MAD study demonstrating that SYN-020 maintained a favorable safety profile and was well-tolerated across all dose levels. There were a few treatment-related adverse events, and all were mild (grade 1) and resolved without medical intervention. The most common adverse event, constipation, occurred in three out of 24 subjects in the treatment arm and in one out of eight subjects in the placebo arm. No adverse event led to discontinuation of the study drug and there were no serious adverse events. Additionally, fecal SYN-020 analyses verified intestinal bioavailability while plasma levels of SYN-020 were below the limit of quantitation in all samples at all timepoints verifying that SYN-020 was not absorbed into the systemic circulation.

During the second quarter of 2020, we announced that we entered into an agreement with Massachusetts General Hospital ("MGH") granting us an option for an exclusive license to intellectual property and technology related to the use of IAP to maintain GI and microbiome health, diminish systemic inflammation, and treat age-related diseases, which option was later amended to include liver fibrosis in select diseases, including NAFLD. The option expired unexercised on July 1, 2024.

The Phase 1 data from our SAD and MAD studies are intended to support the development of SYN-020 in multiple clinical indications including radiation enteritis, NAFLD, celiac disease, and diseases associated with aging. With our transition to an oncology focused company, we are exploring strategic opportunities to enable advancement of this potentially valuable asset.

As part of our strategic transformation into an oncology focused company, we are exploring value creation options for our SYN - 004 and SYN - 020 assets, including out - licensing or partnering.

VCN-01 + Topoisomerase Inhibitors

On May 10, 2024, we presented non-clinical describing enhanced anti-tumor effects in human pancreatic cancer xenograft-bearing mice treated with lead product candidate VCN-01 and liposomal irinotecan in a poster at the 27^th American Society of Gene and Cell Therapy (ASGCT) 2024 Congress held in Baltimore (Maryland) from May 7-11, 2024. These data support the potential synergy of VCN-01 and additional first-line pancreatic cancer chemotherapy regimens FOLFIRINOX and NALIRIFOX. Key findings reported in the poster include:

VCN-X Next Generation OVs and Albumin Shield™ Technology

In parallel with VCN-01 clinical development, we are developing next-generation oncolytic adenoviruses (termed VCN-X) with novel therapeutic payloads and structural modifications designed to increase tumor cell killing and improve systemic virus pharmacokinetics. Preclinical proof-of-concept has been established with VCN-11, which has been engineered to contain all the features of VCN-01 as well as an additional modification to include an albumin binding domain (ABD) in the virus capsid. The virus capsid is the target for neutralizing antibodies (NAbs) that are generated by the host immune system to destroy circulating viruses. The presence of an ABD, however, blocks the binding of most neutralizing antibodies, which allows the virus to reach the tumor following intravenous administration. This "Albumin Shield" works because human blood contains a large amount of albumin to coat the ABD-containing virus. Importantly, this coating of albumin appears to be displaced after the virus reaches tumor cells to infect them. In pre-clinical mouse studies to test the functionality of the "Albumin Shield", mice pre-immunized with virus are able to completely neutralize an unmodified OV because they have a large concentration of neutralizing antibodies in their blood. By contrast, viruses such as VCN-11 that contain the ABD are not neutralized and retain their ability to infect and destroy tumor cells. We believe the results with VCN-11 support the application of the Albumin Shield technology in our VCN-X program to advance treatments for tumors in which rapid multi-dosing may be beneficial.

In March 2021, preclinical data obtained with VCN-11 was published (J Control Release. 2021 Apr 10;332:517-528), showing that the ABD-containing virus induced 450 times more cytotoxicity in tumor cells than in normal cells. Hyaluronidase production was confirmed by measuring the activity of the PH20 enzyme with a hyaluronic acid-degradation assay, and by measuring PH20 activity in VCN-11 infected tumors in vivo. The ABD-containing virus evaded NAbs from different sources and tumor levels of virus were demonstrated in the presence of high levels of NAbs in vivo, whereas the control virus without ABD was neutralized. VCN-11 showed a low toxicity profile in athymic nude mice and Syrian hamsters, allowing treatments with high doses and fractionated administrations without major toxicities (up to 1.2x10¹¹vp/mouse and 7.5x10¹¹vp/hamster). ALT levels were increased on day 3 within an acceptable range that returned to normal levels by day 9. Fractionated intravenous administration of the ABD-containing virus (splitting the dose into two portions administered 4 h apart) appeared to improve virus circulation kinetics and increase tumor levels. Antitumor efficacy was observed in the presence of NAbs against Ad5 and the ABD-containing virus.

In May 2022, we presented data at the 25th Annual Meeting of the American Society of Gene & Cell Therapy (ASGCT). The presentation included preclinical results showcasing the potential of the Albumin Shield Technology to effectively target tumors after intravenous re-administration, even in the presence of high level NAbs, with no major toxicities observed. Our internal VCN-X discovery programs are currently evaluating new oncolytic viruses that contain the Albumin Shield technology and may expand the potential efficacy of Theriva's oncolytic viruses.

In October 2025, Dr. Ramón Alemany, co-founder of VCN (now Theriva Biologics S.L.) and Head of the Immunotherapy and Virotherapy Group at the ProCURE Program of the Catalan Institute of Oncology (ICO) and the Oncobell Program of the Biomedical Research Institute of Bellvitge (IDIBELL) in Barcelona, presented new mechanistic and preclinical data for VCN-12, a next generation oncolytic adenovirus selected from our VCN-X discovery program at the 32^nd Annual Congress of the European Society of Gene & Cell Therapy (ESGCT) in Seville, Spain. VCN-12 is derived from lead clinical product VCN-01 (zabilugene almadenorepvec) and is armed with additional transgenes designed to improve tumor cell lysis, enhance stroma degradation, and augment the antitumor immune response.

THERICEL suspension cell lines for viral manufacturing

The THERICEL program is advancing a proprietary A549 suspension cell line for use in the manufacture of viral therapeutics. These cells are entering feasibility studies to support significant scale - up and potential Phase 3 GMP manufacture of VCN-01 for use in clinical trials. The use of the THERICEL suspension cells is expected to increase the efficiency and significantly reduce the cost of manufacture for VCN - 01 and other viral therapies.

We also have a Spanish government funded collaboration with the Universitat Autònoma de Barcelona to adapt the THERICEL suspension cell platform for the clinical manufacture of adeno - associated virus ("AAV") therapies. If successful, adaptation of the THERICEL platform to AAV manufacture provides an opportunity for potential commercial collaborations in the manufacture of a range of gene therapy products.

Intellectual Property

All of our programs are supported by growing patent estates. In total, Theriva Biologics has over 135 U.S. and foreign patents and over 50 U.S. and foreign patents pending. VCN, through assignment or exclusive licenses, controls over 50 U.S. and foreign patents and over 15 U.S. and foreign patents pending.

The SYN-004 (ribaxamase) program is supported by intellectual property ("IP") that is assigned to Theriva Biologics, namely U.S. and foreign patents (in most major markets, e.g. Europe (including Germany, Great Britain and France), Japan, China and Canada, among others) and U.S. and foreign patents pending (in most major markets, e.g. Europe (including Germany, Great Britain and France), Japan, China and Canada, among others). For instance, U.S. Patent Nos. 8,894,994 and 9,587,234, which include claims to compositions of matter and pharmaceutical compositions of beta-lactamases, including SYN-004 (ribaxamase), have patent terms to at least 2031. Further, U.S. Patent 9,301,995 and 9,301,996, both of which will expire in at least 2031, cover various uses of beta-lactamases, including SYN-004 (ribaxamase), in protecting the microbiome, and U.S. Patent Nos. 9,290,754, 9,376,673, 9,404,103, 9,464,280, and 9,695,409 which will expire in at least 2035, covers further beta-lactamase compositions of matter related to SYN-004 (ribaxamase).

The SYN-020 (oral intestinal alkaline phosphatase (IAP)) program is supported by IP that is assigned to Theriva Biologics, namely U.S. and foreign patents and patent applications (in many major markets, e.g. Europe, China, Japan, Korea, Canada, and Australia). These patents and patent applications, which cover various formulations, medical uses and manufacture of SYN-020, are expected to expire in 2038-2040, without taking potential patent term extensions or patent term adjustment into account.

The VCN-01 and Albumin Shield programs are supported by U.S. and foreign patents and patent applications that are assigned to VCN or exclusively licensed from Fundació Privada Institut d'Investigacio Biomedica de Bellvitge (IDIBELL), Institut Catala d'Oncologia (ICO), and Hospital Sant Joan de Déu in Barcelona. The patents and patent applications include U.S. patents and foreign patents (in most major markets, e.g. Europe, China, Japan, Korea, Canada, Israel, Mexico, Russia, and Australia) and U.S. and foreign patents pending (in most major markets, e.g. Europe, China, Korea, Canada, Mexico, and India). The patents and patent applications cover compositions of matter and pharmaceutical compositions of oncolytic adenoviruses and various medical uses of the same. For instance, U.S. Patent No. 10,316,065, which expires in 2030 without taking potential patent term extensions or patent term adjustment into account, provides composition of matter and pharmaceutical composition coverage for a genus of engineered oncolytic adenovirus suitable for the treatment of solid tumors. Other patents and patent applications, if granted, will provide protection to 2037 without taking potential patent term extensions or patent term adjustment into account.

Our goal is to (i) obtain, maintain, and enforce patent protection for our products, formulations, processes, methods, and other proprietary technologies, (ii) preserve our trade secrets, and (iii) operate without infringing on the proprietary rights of other parties worldwide. We seek, where appropriate, the broadest intellectual property protection for product candidates, proprietary information, and proprietary technology through a combination of contractual arrangements and patents.

Critical Accounting Estimates

The preparation of our consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) requires the use of estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of expenses in the periods presented. We believe that the accounting estimates employed are appropriate and resulting balances are reasonable; however, due to inherent uncertainties in making estimates, actual results may differ from the original estimates, requiring adjustments to these balances in future periods.

There are accounting policies, each of which requires significant judgments and estimates on the part of management, that we believe are significant to the presentation of our consolidated financial statements. The most significant accounting estimates relate to goodwill and IPR&D, research and development costs, and contingent consideration.

Goodwill and IPR&D

We classify intangible assets into two categories: (1) intangible assets with indefinite lives not subject to amortization and (2) goodwill. Intangible assets that are deemed to have indefinite lives, including goodwill, are reviewed for impairment annually, or more frequently if events or changes in circumstances indicate that the asset might be impaired. The impairment test for indefinite-lived intangibles, other than goodwill, consists of a comparison of the fair value of the intangible asset with their carrying amount. If the carrying amount exceeds the fair value, an impairment charge is recognized in an amount equal to that excess. Indefinite-lived intangible assets, such as goodwill, are not amortized. We test the carrying amounts of goodwill for recoverability on an annual basis or when events or changes in circumstances indicate evidence a potential impairment exists, using a fair value-based test. If a reporting unit's carrying value exceeds its fair value, then we will record a goodwill impairment charge for the excess amount.

IPR&D assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development projects. IPR&D assets represent the fair value assigned to technologies that we acquire, which at the time of acquisition have not reached technological feasibility and have no alternative future use. IPR&D is capitalized at its fair value as an indefinite-lived intangible asset, and any development costs incurred after the acquisition are expensed as incurred. During the period that the assets are considered indefinite-lived, they are tested for impairment on an annual basis, or more frequently if we become aware of any events occurring or changes in circumstances that indicate that the fair value of the IPR&D assets are less than their carrying amounts. If and when development is complete, which generally occurs upon regulatory approval and the ability to commercialize products associated with the IPR&D assets, these assets are then deemed definite-lived and are amortized based on their estimated useful lives at that point in time. If development is terminated or abandoned, we may have a full or partial impairment charge related to the IPR&D assets, calculated as the excess of carrying value of the IPR&D assets over fair value.

Goodwill represents the excess of the purchase price paid when we acquired VCN in March 2022, over the fair values of the acquired tangible or intangible assets and assumed liabilities. We conduct an impairment test of goodwill on an annual basis as of October 1 of each year and will also conduct tests if events occur or circumstances change that would, more likely than not, reduce our fair value below our net equity value.

Contingent Consideration

Consideration paid in a business combination may include potential future payments that are contingent upon the acquired business achieving certain milestones in the future ("contingent consideration"). Contingent consideration liabilities are measured at their estimated fair value as of the date of acquisition, with subsequent changes in fair value recorded in the consolidated statements of operations. We estimate the fair value of the contingent consideration as of the acquisition date using the estimated future cash outflows based on the probability of meeting future milestones. The milestone payments will be made upon the achievement of clinical and commercialization milestones. Subsequent to the date of acquisition, we reassess the actual consideration earned and the probability-weighted future earn-out payments at each balance sheet date. Any adjustment to the contingent consideration liability will be recorded in the consolidated statements of operations. Contingent consideration liabilities expected to be settled within 12 months after the balance sheet date are presented in current liabilities, with the non-current portion recorded under long term liabilities in the consolidated balance sheets.

Research and Development Costs

We expense research and development costs associated with developmental products not yet approved by the FDA to research and development expense as incurred. Research and development costs consist primarily of license fees (including upfront payments), milestone payments, manufacturing costs, salaries, stock-based compensation and related employee costs, fees paid to consultants and outside service providers for laboratory development, legal expenses resulting from intellectual property prosecution and other expenses relating to the design, development, testing and enhancement of our product candidates. Research and development expenses include external CRO services. We make payments to the CROs based on agreed upon terms and may include payments in advance of study services. We review and accrue CRO expenses based on services performed and rely on estimates of those costs applicable to the stage of completion of study as provided by the CRO. Accrued CRO costs are subject to revisions as such studies progress to completion. At September 30, 2025 and 2024, we have accrued CRO expenses of $1.7 million and $2.4 million, respectively, that are included in accrued expenses. As of September 30, 2025 and 2024, we have prepaid CRO costs of zero and $0.4 million, respectively, that are included in prepaid expenses.

Results of Operations

Three Months Ended September 30, 2025 and 2024

General and Administrative Expenses

General and administrative expenses decreased to $1.9 million for the three months ended September 30, 2025, from $2.3 million for the three months ended September 30, 2024. This decrease of 18% is primarily comprised of the decrease in compensation costs offset by the increase in the fair value of the contingent consideration and increased investor relations expense. The charge related to stock-based compensation expense was $118,000 for the three months ended September 30, 2025, compared to $118,000 for the three months September 30, 2024. We expect general and administrative expenses to decrease due to the workforce reduction implemented on September 30, 2025.

Research and Development Expenses

Research and development expenses decreased to $2.6 million for the three months ended September 30, 2025, from approximately $2.7 million for the three months ended September 30, 2024. This decrease of 7% is primarily the result of lower clinical trial expenses related to the completion of our VIRAGE Phase 2b clinical trial of VCN-01 in PDAC, lower indirect cost related to compensation and lower clinical trial expenses related to our Phase 1b/2a clinical trial of SYN-004 (ribaxamase) in allogeneic HCT recipients, offset by higher patent expenses related to SYN-020. We anticipate research and development expense to decrease subsequent to the completion of our VIRAGE Phase 2b clinical trial of VCN-01 as we focus on regulatory interactions around potential pivotal clinical trials of VCN-01 in PDAC and retinoblastoma, continue exploratory VCN-01 manufacturing scale-up activities, and continue supporting our other preclinical and discovery initiatives. The charge related to stock-based compensation expense was $110,000 for the three months ended September 30, 2025, compared to $59,000 related to stock-based compensation expense for the three months ended September 30, 2024.

The following table sets forth our research and development expenses directly related to our product candidates for the three months ended September 30, 2025 and 2024. These direct expenses were external costs associated with preclinical studies and clinical trials. Indirect research and development expenses related to employee costs, facilities, stock-based compensation and research and development support services that are not directly allocated to specific product candidates.

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IPRD and Goodwill Impairment

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During the three months ended September 30, 2024, we experienced a sustained decline in the quoted market price of our Common Stock and we deemed this to be a triggering event for impairment. We performed an interim impairment analysis using the "Income approach" that requires significant judgments, including primarily the estimation of future development costs, the probability of success in various phases of our development programs, potential post-launch cash flows and a risk-adjusted weighted average cost of capital. We concluded that the in-process R&D with a carrying value of $19.8 million was written down to its estimated fair value of $18.6 million and an impairment charge of $1.3 million was recorded, and goodwill with a carrying value of $1.5 million was written down to its estimated fair value of zero and an impairment charge of $1.5 million was recorded during the quarter. The decrease in the valuation was primarily driven by an increase in the discount rate which was impacted by an increase in the company specific risk premium, and not by material changes to the clinical and administrative operations of the business. There were no impairment indicators present during the three months ended Septemebr 30, 2025.

Other Income/Expense

Other income was $79,000 for the three months ended September 30, 2025 compared to other income of $161,000 for the three months ended September 30, 2024. Other income for the three months ended September 30, 2025 is primarily comprised of interest income of $65,000 and an exchange gain of $14,000. Other income for the three months ended September 30, 2024 is primarily comprised of interest income of $158,000 and exchange gain of $3,000.

Net Loss

Our net loss for the three months ended September 30, 2025 was $4.4 million, or ($0.45) per common share, compared to $7.7 million, or ($6.81) per common share for the three months ended September 30, 2024.

Nine Months Ended September 30, 2025 and 2024

General and Administrative Expenses

General and administrative expenses increased to $14.5 million for the nine months ended September 30, 2025, from $5.7 million for the nine months ended September 30, 2024. This increase of 155% is primarily comprised of the increase in fair value of the contingent consideration adjustment of $9.2 million due to the VIRAGE Phase 2b clinical trial of VCN-01 in PDAC achieving its primary survival and safety endpoints offset by decrease in compensation costs. The charge related to stock-based compensation expense was $269,000 for the nine months ended September 30, 2025, compared to $335,000 for the nine months ended September 30, 2024. We expect general and administrative expenses to decrease due to the workforce reduction implemented on September 30, 2025.

Research and Development Expenses

Research and development expenses decreased to $7.5 million for the nine months ended September 30, 2025, from approximately $9.1 million for the nine months ended September 30, 2024. This decrease of 18% is primarily the result of lower clinical trial expenses related to the completion of our VIRAGE Phase 2b clinical trial of VCN-01 in PDAC, lower clinical trial expenses related to our Phase 1b/2a clinical trial of SYN-004 (ribaxamase) in allogeneic HCT recipients and lower indirect cost related to compensation, offset by higher patent expenses related to SYN-020. We anticipate research and development expense to decrease subsequent to the completion of our VIRAGE Phase 2b clinical trial of VCN-01 as we focus on regulatory interactions around potential pivotal clinical trials of VCN-01 in PDAC and retinoblastoma, continue exploratory VCN-01 manufacturing scale-up activities, and continue supporting our other preclinical and discovery initiatives. The charge related to stock-based compensation expense was $232,000 for the nine months ended September 30, 2025, compared to $175,000 related to stock-based compensation expense for the nine months ended September 30, 2024.

The following table sets forth our research and development expenses directly related to our product candidates for the nine months ended September 30, 2025 and 2024. These direct expenses were external costs associated with preclinical studies and clinical trials. Indirect research and development expenses related to employee costs, facilities, stock-based compensation and research and development support services that are not directly allocated to specific product candidates.

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IPRD and Goodwill Impairment

During the nine months ended September 30, 2024, we experienced a sustained decline in the quoted market price of our Common Stock and we deemed this to be a triggering event for impairment. We performed an interim impairment analysis using the "Income approach" that requires significant judgments, including primarily the estimation of future development costs, the probability of success in various phases of its development programs, potential post-launch cash flows and a risk-adjusted weighted average cost of capital. We concluded that the in-process R&D with a carrying value of $19.8 million was written down to its estimated fair value of $18.6 million and an impairment charge of $1.3 million was recorded, and goodwill with a carrying value of $5.6 million was written down to its estimated fair value of zero and an impairment charge of $5.6 million was recorded during the nine months ended September 30, 2024. The decrease in the valuation was primarily driven by an increase in the discount rate which was impacted by an increase in the company specific risk premium, and not by material changes to the clinical and administrative operations of the business. There were no impairment indicators present during the nine months ended Septemebr 30, 2025.

Other Income/Expense

Other income was $245,000 for the nine months ended September 30, 2025 compared to other income of $560,000 for the nine months ended September 30, 2024. Other income for the nine months ended September 30, 2025 is primarily comprised of interest income of $215,000 and an exchange gain of $30,000. Other income for the nine months ended September 30, 2024 is primarily comprised of interest income of $559,000 and exchange gain of $1,000.

Net Loss Attributable to Common Stockholders

Our net loss attributable to common stockholders was approximately $21.7 million, or ($3.38) per basic and diluted common share for the nine months ended September 30, 2025, compared to a net loss of approximately $21.2 million, or ($24.47) per basic common share and diluted common share for the nine months ended September 30, 2024.

Liquidity and Capital Resources

As of September 30, 2025, we had a significant accumulated deficit, and with the exception of the three months ended June 30, 2010 and the three months ended December 31, 2017, we have experienced significant losses and incurred negative cash flows since inception. We have incurred an accumulated deficit of $356.7 million as of September 30, 2025, and expect to continue to incur losses in the foreseeable future with the recognition of revenue being contingent on successful phase 3 clinical trials and requisite approvals by the FDA or foreign equivalents.

Our cash and cash equivalents totaled $7.5 million as of September 30, 2025, a decrease of $4.1 million from December 31, 2024. However, subsequent to September 30, 2025, our cash position increased to $15.5 million as a result of our receipt of $6.1 in net proceeds from sales made pursuant to the ATM Sales Agreement and $4.0 million in net proceeds in connection with the warrant inducement consummated in October 2025. During the year ended December 31, 2024 and nine months ended September 30, 2025, the primary use of cash was for working capital requirements and operating activities which resulted in a net loss of $25.6 million and $21.7 million.

We believe our cash position of $15.5 million as of early November 2025, will allow us to fund our operations into the first quarter of 2027. However, despite this liquidity position, we continue to experience operating losses and face significant uncertainties related to our business model, market conditions, clinical trial outcomes, FDA review timelines and strategic initiatives. These factors raise substantial doubt about our ability to continue as a going concern beyond the next twelve months without additional capital or other strategic actions. Management has developed plans intended to mitigate these uncertainties, including pursuing strategic collaborations, securing additional financing, and prioritizing key development programs. While management believes these plans are probable of being successfully implemented, there can be no assurance that such actions will be sufficient to alleviate the going concern uncertainty.

Based on our current plans, our cash and cash equivalents will be sufficient to cover overhead costs, close out of the VIRAGE Phase 2b clinical trial, exploratory VCN-01 manufacturing scale-up activities, regulatory interactions regarding proposed VCN-01 clinical trials in PDAC and retinoblastoma, and preclinical studies supporting VCN-01 and VCN-12, the first candidate from our VCN-X discovery program. The cash is also sufficient to fund our committed obligations under the terms of the VCN share purchase agreement (the "VCN Purchase Agreement") related to the Acquisition, but will not be sufficient for additional trials of VCN-01, SYN-020 or SYN-004, or to complete the last cohort of the Phase 1b/2a clinical trial of SYN-004, which are expected to require significant cash expenditures. Following the completion of our ongoing Phase 1 and Phase 2b clinical trials for VCN-01, and preclinical studies supporting VCN-01

and our discovery initiatives, we will need to obtain additional funds for future clinical trials. We anticipate that our future clinical trials will be much larger in size and require larger cash expenditures than the aforementioned clinical programs. We do not have any committed sources of financing for future clinical trials at this time, and it is uncertain whether additional funding will be available when we need it on terms that will be acceptable to us, or at all. Management believes its plan, which is focused on the advancement of VCN-01, will allow us to meet our financial obligations, further advance key products, and maintain our planned operations. Based upon our current available funding and our focus on our clinical development of VCN-01 we do not anticipate that we will fund the last cohort of the Phase 1b/2a clinical trial of SYN-004 and enrollment in this cohort will not commence unless we obtain grant funding, or find a licensee or partner for the SYN-004 development program. However, the amount of additional capital needed by us will also depend upon the costs to advance our VCN-01 clinical programs. If necessary, we may attempt to utilize the ATM Sales Agreement or seek to raise additional capital in other financing transactions, neither of which is guaranteed. Use of the ATM Sales Agreement is limited by certain restrictions and management's plan does not rely on additional capital from any sources. If we are not able to obtain additional capital (which is not assured at this time), our long-term business plan may not be accomplished, and we may be forced to cease certain development activities. More specifically, the completion of any later stage clinical trial will require significant financing or a significant partnership.

Historically, we have financed our operations primarily through public and private sales of our securities, and we expect to continue to seek and obtain additional capital in a similar manner. During the year ended December 31, 2024, our only source of cash was from sales of our Common Stock through the ATM Sales Agreement pursuant to which we sold 569,000 shares of our Common Stock for net proceeds of $3.6 million and from the sale of our securities in our public offering of 918,600 shares of Common Stock in combination with accompanying warrants to purchase an aggregate of 1,428,600 shares of the Common Stock for gross proceeds of $2.5 million (net proceeds of $2.0 million, after deducting underwriting discounts and estimated expenses). During the three and nine months ended September 30, 2025, we sold approximately 706,810 shares of our Common Stock pursuant to the ATM Sales Agreement and received net proceeds of approximately $279,000. During October 2025, we sold through the Sales Agreement approximately 15,342,601 shares of our Common Stock pursuant to the ATM Sales Agreement and received net proceeds of approximately $6.1 million. During the nine months ended September 30, 2025, the primary source of cash was from the $1.7 million received for the Research and Development rebate program, $1.4 million for the THERICEL project loan from the National Knowledge Transfer Program of the Spanish government's Ministry of Science and, in May 2025, we closed our May 2025 Offering of 6,818,180 shares of Common Stock (or Pre-Funded Warrants in lieu thereof) in combination with accompanying Common Warrants to purchase an aggregate of 6,818,180 shares of the Common Stock for gross proceeds of $7.5 million (net proceeds of $6.9 million, after deducting underwriting discounts and estimated expenses).

Pursuant to the terms of the VCN Purchase Agreement, we were required to pay up to $70.2 million in additional consideration upon the achievement of certain milestones, including regulatory filings of which to date $6.8 million has been paid. In September 2022, we received approval from the FDA to proceed with the Phase 2 clinical trial of VCN-01 in metastatic pancreatic ductal adenocarcinoma (mPDAC). Due to this approval we paid Grifols Innovation and New Technologies Limited ("Grifols"), $3.0 million in the fourth quarter 2022. In August 2023, we initiated patient dosing in the U.S. in our Phase 2 clinical trial of VCN-01 in mPDAC. As a result, payment was made subsequent to September 30, 2023 in the amount of $3.25 million. During the three months ended June 30, 2025, we met the primary survival and safety endpoints in our VIRAGE Phase 2b clinical trial evaluating our lead product candidate VCN-01. As a result of achieving the primary survival and safety endpoints in the Phase 2b clinical trial, we are obligated to pay Grifols $6 million. On August 5, 2025, we and Grifols agreed to deferring the $6 million milestone payment into three payments; $500,000 was paid in August 2025, $500,000 will be paid by the end of December 2025, and the remaining $5 million payment will be deferred until a licensing or business development transaction is secured.

There can be no assurance that we will be able to continue to raise funds through the sale of shares of Common Stock through the ATM Sales Agreement or other equity financings. If we raise funds by selling additional shares of Common Stock or other securities convertible into Common Stock, the ownership interest of our existing stockholders will be diluted. If we are not able to obtain funding for future clinical trials when needed, we will be unable to carry out our business plan and we will be forced to delay the initiation of future clinical trials until such time as we obtain adequate financing and may need to abandon some of our development programs, cease operations, liquidate our assets or reorganize the Company, or a combination of the foregoing.

We have spent, and expect to continue to spend, a substantial amount of funds in connection with implementing our business strategy, including our planned product development efforts, preparation for our planned clinical trials, performance of clinical trials and our research and discovery efforts. We will be required to obtain additional funding in order to continue the development of certain product candidates within the anticipated time periods (including initiation of planned clinical trials), if at all, and to continue to fund operations at the current cash expenditure levels. We do anticipate that our current cash of approximately $15.5 million as of early November 2025

will allow us to fund our operations into the first quarter of 2027, including overhead costs, close out of the VIRAGE Phase 2b clinical trial; exploratory VCN-01 manufacturing scale-up activities, regulatory interactions regarding proposed VCN-01 clinical trials in PDAC and retinoblastoma, and preclinical studies supporting VCN-01 and VCN-12, the first candidate from our VCN-X discovery program. The cash is also sufficient to fund our committed obligations under the terms of the VCN Purchase Agreement related to the Acquisition. Our ability to continue as a going concern is dependent upon our ability to obtain additional equity or debt financing, attain further operating efficiencies, reduce expenditures, and, ultimately, to generate revenue. Our notes to the consolidated financial statements contain an explanatory paragraph referring to our recurring and continuing losses from operations and expressing substantial doubt in our ability to continue as a going concern without additional capital becoming available. We cannot provide any assurance that we will be able to obtain the required funding to achieve our current business plan, obtain the required regulatory approvals for our product candidates or complete additional corporate partnering or acquisition transactions in order to commercialize such product candidates once regulatory approval is received. If we fail to obtain additional funding for our clinical trials, whether through the sale of securities or a partner or collaborator, and otherwise when needed, we will not be able to execute our business plan as planned and will be forced to cease certain development activities (including initiation of planned clinical trials) until funding is received and our business will suffer, which would have a material adverse effect on our financial position, results of operations and cash flows.

Our ability to continue as a going concern is dependent upon our ability to raise additional capital. Our cash and cash equivalents will not be sufficient to initiate or complete future registrational studies for VCN-01, any potential future trials of SYN-004 including Phase 3 clinical programs of SYN-004 (ribaxamase) for prevention of CDI or the Phase 1b/2a clinical study of SYN-004 (ribaxamase) in allogeneic HCT recipients, or later-stage clinical trials of SYN-020. Therefore, we do not intend to commence future new studies of VCN-01, SYN-004 (ribaxamase) or SYN-020 until we are confident that we have funding necessary to complete such trials. We are actively pursuing additional equity or debt financing, in the form of either a private placement or a public offering and have been in ongoing discussions with strategic institutional investors and investment banks with respect to such possible offerings. However, we do not currently have commitments from any third parties to provide us with capital. Potential sources of financing that we are pursuing include strategic relationships, licensing arrangements, public or private sales of our equity (including through the ATM Sales Agreement) or debt and other sources. Such additional financing opportunities might not be available to us when and if needed, on acceptable terms or at all. We cannot assure that we will meet the requirements for use of the ATM Sales Agreement especially in light of the fact that we are currently limited by rules of the Securities and Exchange Commission (the "SEC") as to the number of shares of Common Stock that we can sell pursuant to the ATM Sales Agreement due to the market value of our Common Stock held by non-affiliates. Even if we meet the requirements for use of the ATM Sales Agreement, there can be no assurance that we will be able to raise funds through the sale of shares of Common Stock through the ATM Sales Agreement. Additionally, we may seek to access the public or private equity markets when conditions are favorable due to our long-term capital requirements. If we are unable to obtain additional capital (which is not assured at this time), our long-term business plan may not be accomplished and we may be forced to cease certain development activities. More specifically, the completion of future Phase 3 and/or registrational clinical studies will require significant financing or a significant partnership. If we raise funds by selling additional shares of Common Stock or other securities convertible into Common Stock, the ownership interest of our existing stockholders will be diluted. If we are not able to obtain funding for future clinical trials when needed, we will be unable to carry out our business plan and we will be forced to delay the initiation of future clinical trials until such time as we obtain adequate financing and our operating results and prospects will be adversely affected.

Cash Flows

The following table summarizes our cash flows for the periods presented:

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Cash Used in Operating Activities

Net cash used in operating activities was $13.8 million and $12.2 million during the nine months ended September 30, 2025 and 2024, respectively, which was primarily due to the use of funds in our operations related to the development of VCN-01 our product candidate.

Cash Used in Investing Activities

Cash used in investing activities during the nine months ended September 30, 2025 and 2024 was $35,000 and $1,000, respectively, for equipment purchases.

Cash Provided By Financing Activities

Cash provided by financing activities during the nine months ended September 30, 2025 included $1.8 million received for the research and development tax credit, $1.5 million in loan proceeds from the THERICEL project loan, $6.7 million in net proceeds from the sale of Common Stock and at the market offering proceeds of $279,000 from sales of 706,810 shares of our Common Stock pursuant to the ATM Sales Agreement offset by payments of loans in the amount of $69,000 and payment of contingent consideration of $500,000. Cash provided by financing activities during the nine months ended September 30, 2024 included at the market offering proceeds of $3.6 million from sales of 569,000 shares of our Common Stock offset by payments related to loans extended by certain Spanish institutions of $67,000 and net proceeds of $2.0 million from the sale of our securities in our public offering of 918,600 shares of Common Stock in combination with accompanying warrants to purchase an aggregate of 1,428,600 shares.

Off-Balance Sheet Arrangements

During the three months ended September 30, 2025, we did not have, and we do not currently have, any off-balance sheet arrangements, as defined under SEC rules.

Contractual Obligations

Leases

At the inception of a contract we determine if the arrangement is, or contains, a lease. Right of use ("ROU") assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term.

We have made certain accounting policy elections whereby we (i) do not recognize ROU assets or lease liabilities for short-term leases (those with original terms of 12-months or less) and (ii) combine lease and non-lease elements of our operating leases. As of September 30, 2025, we did not have any material finance leases.

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