Quarterly Report for Quarter Ending September 30, 2026 (Form 10-Q)

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Clinical Pipeline

Iopofosine I 131 - Background

The U.S. Food and Drug Administration (FDA) granted iopofosine I 131 Break-through Designation for r/r WM and Fast Track Designation (FTD) for lymphoplasmacytic lymphoma (LPL) and WM patients having received two or more prior treatment regimens, as well as r/r MM and r/r diffuse large B-cell lymphoma (DLBCL). Orphan Drug Designations (ODDs) have been granted for LPL/WM, MM, neuroblastoma, soft tissue sarcomas including rhabdomyosarcoma, Ewing's sarcoma and osteosarcoma. Iopofosine was also granted Rare Pediatric Disease Designation (RPDD) for the treatment of neuroblastoma, rhabdomyosarcoma, Ewing's sarcoma and osteosarcoma. The European Commission granted iopofosine PRIME Designation for WM and ODD for treatment of r/r MM and WM.

Additionally, in June 2020, the European Medicines Agency's (EMA) Micro, Small and Medium-sized Enterprise office granted Cellectar Small and Medium-Sized Enterprise (SME) status. SME status allows us to participate in significant financial incentives that include a 90% to 100% EMA fee reduction for scientific advice, clinical trial protocol design assistance, endpoints and statistical considerations assistance, and fees for pre- and post-authorization regulatory inspections as well as fee waivers for selective EMA pre-and post-authorization regulatory filings, including orphan drug and PRIME designations. We are also eligible to obtain EMA certification of quality and non-clinical data. Other financial incentives include EMA-provided translational services of all regulatory documents required for market authorization, further reducing the financial burden of the market authorization process.

Iopofosine I 131 - Clinical Trials

CLOVER WaM Phase 2b WM Pivotal Registration Trial - Initial Top Line Data

Based upon the clinical results from our Phase 2a CLOVER-1 clinical trial which showed a 100% ORR in six WM patients and an 83.3% MRR with one patient achieving a complete response (CR) lasting 39 months post-last treatment the CLOVER WaM Phase 2b trial was designed as a pivotal registration trial evaluating iopofosine in WM patients that were r/r to at least two prior lines of therapy including having failed or having a suboptimal response to a BTKi.

The CLOVER WaM Phase 2b trial completed enrollment in the fourth quarter of 2023, and initial top line data from the trial was reported in January 2024. CLOVER-WaM was a single-arm trial with a target enrollment of 50 patients. Based upon the data from September 2024, the CLOVER WaM trial enrolled a total of 55 patients in the modified Intent to Treat (mITT) population and met its primary endpoint with a major response rate (MRR) of 58.2% (95% confidence interval [44.50%, 75.80%, two-sided p value < 0.0001]) exceeding the FDA agreed-upon statistical hurdle of 20%. The overall response rate (ORR) in evaluable patients was 83.6%, and 98.2% of patients experienced disease control. Responses were durable, with median duration of response not reached at 11.4 months of follow-up and 76% of patients remaining progression free at a median follow-up of eight months. These outcomes exceed historic real-world data which demonstrate a 4-12% MRR and a duration of response of approximately six months in a patient population that is less pretreated and not refractory to multiple classes of drugs. Notably, an iopofosine I 131 monotherapy achieved a 7.3% complete remission (CR) rate in this highly refractory WM population. Overall, 45 (69.2%) patients had prior exposure to at least 3 classes of drugs, and 19 (29.2%) patients had prior exposure to at least 4 drug classes of anti-cancer therapies. Forty-eight (73.8%) patients had prior exposure to a BTKi of which 37 (77.1%) were deemed to be refractory to BTKis. Forty-three (66.2%) patients were exposed to BTKi and anti-CD20 antibody with 25 (58.1%) being refractory to both BTKi and anti-CD-20 antibodies. Thirty-seven (56.9%) patients had prior exposure to BTKi, anti-CD20 antibody, and chemotherapy and 18 (48.6%) patients were refractory to all three classes of drugs, BTKi, anti-CD20 antibody, and chemotherapy. Iopofosine I 131 was well tolerated and its toxicity profile was consistent with the Company's previously reported safety data. The safety population was 65 patients which included patients that received at least a single dose of iopofosine I 131 but did not receive the necessary total body dose required for an efficacy assessment. There were 3 (4.6%) patients that experienced treatment-related adverse events (TRAEs) leading to discontinuation. The rates of greater TRAEs observed in more than 10% of patients included thrombocytopenia (56 [86.2%] patients), neutropenia (52 [80.0%] patients), anemia (42 [64.6%] patients) and decreased white blood cell count (21 [32.3%] patients) among hematologic toxicities and fatigue (22 [33.8%] patients), nausea (19 [29.2%] patients) and diarrhea (13 [20.0%] patients) among non-hematologic toxicities. The rates of Grade 3 or greater TRAEs observed in more than 10% of patients included thrombocytopenia (53 [81.5%] patients), neutropenia (43 [66.2%] patients), anemia (31 [47.7%] patients), decreased white blood cell count (18 [27.7%]), decreased lymphocyte count 8 (12.3%). All patients recovered from cytopenias with no reported aplastic sequelae. Importantly, there were no clinically significant bleeding events, and the rate of febrile neutropenia was 10.8%. There were no treatment-related deaths in the trial.

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CLOVER-WaM Phase 2b WM Pivotal Registration Trial - 12-Month Follow-Up Data

On May 5, 2026, the Company reported positive 12-month follow-up data from its Phase 2b CLOVER WaM clinical trial evaluating iopofosine I 131 in the per protocol trial population (n=55) patients with r/r WM. The Company announced that 83.6% Overall Response Rate ("ORR") and 61.8% Major Response Rate ("MRR") were observed in the heavily pretreated population with median duration of response (DoR) of 17.8 months, which represents the achievement of the secondary endpoint. Median Progression-Free Survival (PFS) was 13.5 months, with a Very Good Partial Response/Complete Response Rate (VGPR/CR) of 14.5%, and a Disease Control Rate (DCR) of 98.2%.

Additionally, the subset efficacy results in BTKi-Exposed Patients (n=39) were observed to be an MRR of 64.1%, with a DoR of 18.2 months and PFS of 15.9 months. In BTKi-Refractory Patients (n=33), these observed rates were MRR of 63.6%, DoR of 18.2 months and PFS of 14.8 months. In the trial, observed adverse events were transient and there were no significant bleeding events and low rates of infection (<10%). Cytopenias were the most common treatment-emergent adverse events. Non-hematologic toxicities were primarily low grade (Grade <2).

Phase 3 WM Confirmatory Trial - Overview

On March 6, 2025, the Company conducted its End-of-Phase-2 (EOP2) meeting with the U.S. Food and Drug Administration (FDA). As a result of the meeting, and clarified by subsequent written correspondence, the Company believes that it understands a path forward for potential accelerated and full approval of iopofosine I 131 in WM based upon the CLOVER WaM trial and the initiation of a comparator-controlled Phase 3 confirmatory trial assessing progression free survival as the primary endpoint. The Company initiated activities related to the Phase 3 confirmatory trial in June of 2026. These activities include, but are not limited to, selection of and finalizing the contract with the lead Contract Research Organization (CRO), finalizing the protocol and statistical analysis plan, site feasibility and qualification visits. The trial is designed based upon a series of communications with the FDA, including an End-of-Phase-2 (EOP2) meeting. Following FDA guidance, the Company believes that accelerated approval of iopofosine I 131 will be based upon the CLOVER WaM trial and the initiation of a comparator-controlled Phase 3 confirmatory trial assessing progression free survival as the primary endpoint in WM patients. Full approval of iopofosine will be based upon the demonstration of superior progression free survival of iopofosine against a comparator in 2^nd line of therapy or later immediately post BTKi treatment and would be granted accelerated approval if accepted. The submission for accelerated approval utilizing the CLOVER WaM trial data can occur at the time of or after the initiation of this Phase 3 randomized controlled confirmatory trial and patient enrollment must be ongoing at the time of the FDA's decision on the accelerated NDA. The Company is currently preparing a Phase 3 trial that will be a comparator, randomized controlled trial with approximately 100 WM patients per arm; full patient enrollment is projected within 18-24 months of the first patient admitted. The Company anticipates the first patient to be enrolled in the first quarter of 2027.

Phase 1b/2a Iopofosine I 131 Dosimetry Trial

The Phase 1b/2a dosimetry trial is an open label, multicenter trial evaluating dosimetry, safety, and efficacy of iopofosine I 131 in WM participants. The trial was recommended by the FDA and the data are planned to be included in the full approval application post the completion of the Phase 3 confirmatory trial. Up to 30 participants will be enrolled to assess radiation dosimetry and biodistribution of iopofosine I 131. Following administration of Cycle 1 Day 1 and Cycle 2 Day 1 iopofosine I 131 doses, single photon-emission computed tomography/computed tomography (SPECT/CT) imaging will be performed on Day 1 (1 hour post iopofosine I 131 infusion), Day 2 (24 hours post infusion), Day 4 (72 hours post infusion), and Day 11 (240 hours post infusion). Blood samples for dosimetry assessment will be collected on Day 1 (1 hour and 2 hours post iopofosine I 131 infusion), Day 2 (24 hours post infusion), Day 3 (48 hours post infusion), Day 4 (72 hours post infusion), and Day 11 (240 hours post infusion).

The primary endpoint is to characterize total body and normal-organ absorbed doses of iopofosine I 131 in participants with Waldenstrom Macroglobulinemia (WM) at the defined fixed dose of 15 mCi/m2 given day 1 and 15 of each cycle and to estimate cumulative absorbed dose across the planned administrations. The secondary and exploratory efficacy endpoints include determination of MRR, ORR, DOR, PFS, OS, individual rates of response (CR, VGPR, PR, MR, SD), TFS, and TtNT of iopofosine I 131 in participants with WM. In WM, disease is measured by serological markers (e.g., total serum IgM and/or monoclonal M-protein) and, when applicable, radiographically measurable extramedullary lesions. The participants' response will be determined using the modified IWWM-11 response criteria.

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CLOVER-1 Phase 2a Trial: Patients with Select B-Cell Malignancies

In July 2016, the Company was awarded a $2,000,000 National Cancer Institute (NCI) Fast-Track Small Business Innovation Research grant to further advance the clinical development of iopofosine. The funds partly supported the initiation of our Phase 2a CLOVER-1 trial which initiated in March 2017.

The Phase 2a was an open-label trial designed to determine the clinical benefits, the efficacy and safety of CLR 131 in select B-cell malignancies with unmet clinical need including (multiple myeloma (MM), indolent chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), lymphoplasmacytic lymphoma (LPL)/Waldenstrom's macroglobulinemia (WM), marginal zone lymphoma (MZL), mantle cell lymphoma (MCL), DLBCL, and central nervous system lymphoma (CNSL) who have been previously treated with standard therapy for their underlying malignancy. The trial was conducted in approximately 10 U.S. cancer centers in patients with orphan-designated relapse or refractory hematologic cancers. The planned trial enrollment was up to 80 patients. The trial's primary endpoint was clinical benefit response (CBR), with secondary endpoints of ORR, PFS, time to next treatment (TtNT), median Overall Survival (mOS), Duration of Response (DOR) and other markers of efficacy following patients receiving one of three total body doses (TBD) of iopofosine (<50mCi, ~50mCi and >60mCi), with the option for a second cycle approximately 75-180 days later. Dosages were provided either as a single bolus or fractionated (the assigned dose level split into two doses) given day 1 and day 15. Over the course of the trial the dosing regimen of iopofosine advanced from a single bolus dose to two cycles of fractionated administrations of 15 mCi/m2 per dose on days 1, 15 (cycle 1), and days 57, 71 (cycle 2). Adverse events occurring in at least 25% of subjects were fatigue (39%) and cytopenias, specifically, thrombocytopenia (75%), anemia (61%), neutropenia (54%), leukopenia (51%), and lymphopenia (25%). Serious adverse events occurring in greater than 5% of subjects were restricted to thrombocytopenia (9%) and febrile neutropenia (7.5%). As of March 2022, the trial arms for CLL/SLL, LPL/WM, MZL, MCL, and DLBCL were closed. Dosing of patients varied by disease state cohort and was measured in terms of TBD. The trial met the primary endpoints from the Part A dose-finding portion. The following Clover-1 information outlines select patient cohorts.

CLOVER-1 Phase 2a Trial: Patient Cohort with r/r Multiple Myeloma

In September 2020, we announced that a 40% ORR was observed in the subset of refractory MM patients deemed triple class refractory who received 60 mCi or greater TBD. Triple class refractory is defined as patients that are refractory to immunomodulatory, proteasome inhibitors and anti-CD38 antibody drug classes. The 40% ORR (6/15 patients) represents triple class refractory patients enrolled in Part A of Cellectar's CLOVER-1 trial and additional patients enrolled in Part B from March through May 2020 and received >60mCi TBD (25 mCi/m2 single bolus, 31.25 mCi/m2 fractionated, 37.5 mCi/m2 fractionated, or two cycles of mCi/m2 fractionated) either as a bolus dose or fractionated. Patients with MM received 40 mg of dexamethasone concurrently beginning within 24 hours of the first CLR 131 infusion. All MM patients enrolled in the expansion cohort are required to be triple class refractory. The additional six patients enrolled in 2020 were heavily pre-treated with an average of nine prior multi-drug regimens. Three patients received a TBD of > 60 mCi and three received less than 60 mCi. Consistent with the data released in February 2020, patients receiving > 60 mCi typically exhibit greater responses. Study results confirmed that patients continued to tolerate iopofosine well, with the most common and almost exclusive treatment-emergent adverse events are cytopenias, such as thrombocytopenia, neutropenia, and anemia.

In December 2021, we presented data from 11 MM patients from our Phase 2 CLOVER-1 trial in a poster at the American Society of Hematology (ASH) Annual Meeting and Exposition. The MM patients were at least triple class refractory (defined as refractory to an immunomodulatory agent, proteasome inhibitor and monoclonal antibody) with data current as of May 2021. Patients had a median of greater than 7 prior therapies with 50% classified as high risk. Initial results in these patients showed an ORR of 45.5%, a CBR of 72.7%, and a disease control rate (DCR) of 100%. Median PFS was 3.4 months. In a subset of five quad/penta drug refractory patients, efficacy increased, demonstrating an ORR of 80% and CBR of 100% in this highly treatment refractory group. The most observed treatment emergent adverse events were cytopenias that included Grade 3 or 4 thrombocytopenia (62.5%), anemia (62.5%), neutropenia (62.5%) and decreased white blood cell count (50%). Treatment emergent adverse events were mostly limited to bone marrow suppression in line with prior observations. No patients experienced treatment emergent adverse events of neuropathy, arrhythmia, cardiovascular event, bleeding, ocular toxicities, renal function, alterations in liver enzymes, or infusion-site reactions or adverse events.

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The Phase 2b trial evaluated highly refractory MM patients including triple class, quad- and penta-drug refractory patients, and post-BCMA immunotherapy patients. The study also evaluated iopofosine I 131 in r/r CNSL patients. Iopofosine resulted in response rates of 40% in triple class refractory patients, 53.8% in quad/penta drug refractory and 62.5% in high-risk patients. A 50% ORR was reported in patients that were post-BCMA treatment. Treatment emergent adverse events were consistent with previously reported outcomes with cytopenias representing the most commonly reported Grade 3/4 events with almost no off-target events being reported.

Based upon iopofosine being well tolerated across all dose groups, the observed response rate, and in difficult to treat patients such as high risk and triple class refractory or penta-refractory, and corroborating data showing the potential to further improve upon current ORRs and durability of those responses, the trial has been expanded to test a two-cycle dosing optimization regimen with a target TBD >60 mCi/m2 of iopofosine.

CLOVER-1 Phase 2a Trial: Patient Cohort with r/r non-Hodgkin's Lymphoma

In February 2020, we announced positive data from our Phase 2a CLOVER-1 trial in patients with NHL. Patients were treated with three different doses (<50mCi, ~50mCi and >60mCi TBD). Patients in the r/r NHL cohort received TBD of either ≥ 60 mCi or < 60 mCi (25 mCi/m2 single bolus, 31.25 mCi/m2 fractionated, 37.5 mCi/m2 fractionated, or two cycles of mCi/m2 fractionated) either as a bolus dose or fractionated. Patients with r/r NHL who received <60mCi TBD and the >60mCi TBD had a 42% and 43% ORR, respectively and a combined rate of 42%. These patients were also heavily pre-treated, having a median of three prior lines of treatment (range, 1 to 9) with most patients being refractory to rituximab and/or ibrutinib. The patients' median age was 70 with a range of 51 to 86 years of age. All patients had bone marrow involvement with an average of 23%. In addition to these findings, subtype assessments were completed in the r/r B-cell NHL patients. We observed a 30% ORR in patients with DLBCL, with one patient achieving a CR, which continues at more than 99 months post-treatment. The ORR for CLL/SLL and MZL patients was 33%. The most frequently reported adverse events in all patients were cytopenias, which followed a predictable course and timeline. The frequency of adverse events did not increase as doses were increased and the profile of cytopenias remained consistent. Importantly, our assessment is that these cytopenias have had a predictable pattern to initiation, nadir and recovery and are treatable. The most common grade ≥3 events at the highest dose (75mCi TBD) were hematologic toxicities including thrombocytopenia (65%), neutropenia (41%), leukopenia (30%), anemia (24%) and lymphopenia (35%). No patients experienced cardiotoxicities, neurological toxicities, infusion site reactions, peripheral neuropathy, allergic reactions, cytokine release syndrome, keratopathy, renal toxicities, or changes in liver enzymes. The safety and tolerability profile in patients with r/r NHL was similar to r/r MM patients except for fewer cytopenias of any grade.

Phase 1 Trial in Patients with r/r Multiple Myeloma

In February 2020, final results from a multicenter, Phase 1 dose escalation clinical trial of iopofosine in r/r MM were presented. The trial was designed to evaluate the safety and potential initial efficacy of iopofosine administered in an up to 30-minute I.V. infusion either as a single bolus dose or as a fractionated dose in heavily pretreated MM patients. The trial enrolled a total of 26 evaluable patients at three trial sites. For the trial, which used a modified three-plus-three dose escalation design, 15 evaluable patients were dosed in single bolus doses from 12.5mCi/m2 up to 31.25mCi/m2 (TBD 20.35-59.17 mCi) and 11 evaluable patients were dosed in fractionated dosing cohorts of 31.25mCi/m2 to 40mCi/m2 (TBD 54.915-89.107 mCi). An independent Data Monitoring Committee (iDMC) did not identify dose-limiting toxicities in any cohort. Of the 26 evaluable patients in the trial, a partial response was observed in 4 of 26 patients (15.4%) and stable disease or minimal response in 22 of 26 patients (84.6%), for a disease control rate of 100%. A significant decrease in M-protein and free light chain (FLC) was also observed.

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Iopofosine in combination with dexamethasone was under investigation in adult patients with r/r MM. MM is an incurable cancer of the plasma cells and is the second most common form of hematologic cancer. Patients had to be refractory to or relapsed from at least one proteasome inhibitor and at least one immunomodulatory agent. The clinical trial was a standard three-plus-three dose escalation safety trial to determine the maximum tolerable dose. We use the International Myeloma Working Group (IMWG) definitions of response, which involve monitoring the surrogate markers of efficacy, M protein and FLC. The IMWG defines a PR as a 50% or greater decrease in M protein or to 50% or greater decrease in FLC levels (for patients in whom M protein is unmeasurable). Secondary objectives included the evaluation of therapeutic activity by assessing surrogate efficacy markers, which include M protein, FLC, PFS and OS. All patients were heavily pretreated with an average of five prior lines of therapy. An iDMC assessed the safety of iopofosine up to its planned maximum single, bolus dose of 31.25 mCi/m2 or a TBD of ~63 mCi. The four single-dose cohorts examined were: 12.5 mCi/m2 (~25mCi TBD), 18.75 mCi/m2 (~37.5mCi TBD), 25 mCi/m2(~50mCi TBD), and 31.25 mCi/m2(~62.5mCi TBD), all in combination with low dose dexamethasone (40 mg weekly). Of the five patients in the first cohort, four were assessed as achieving stable disease and one patient progressed at Day 15 after administration and was taken off the trial. Of the five patients admitted to the second cohort, all five were assessed as achieving stable disease; however, one patient progressed at Day 41 after administration and was taken off the trial. Four patients were enrolled to the third cohort, and all were assessed as achieving stable disease. In September 2017, we announced safety and tolerability data for cohort 4, in which patients were treated with 31.25 mCi/m2 of iopofosine in a single infusion with a duration of no more than 30 minutes, which was tolerated by the three patients in the cohort. Additionally, all three patients experienced CBR with one patient achieving a partial response (PR). The patient experiencing a PR had an 82% reduction in FLC. This patient did not produce M protein, had received seven prior lines of treatment including radiation, stem cell transplantation and multiple triple combination treatments including one with daratumumab that was not tolerated. One patient experiencing stable disease attained a 44% reduction in M protein. In January 2019, we announced that the pooled mOS data from the first four cohorts was 22.0 months. In late 2018, we modified this trial to evaluate a fractionated dosing strategy to potentially increase efficacy and decrease adverse events.

Cohorts five and six received fractionated dosing of 31.25 mCi/m2(~62.5mCi TBD) and 37.5 mCi/m2 (~75mCi TBD), each administered on day 1 and day 8. Following the determination that all prior dosing cohorts were tolerated, we initiated a cohort seven utilizing a 40mCi/m2 (~95mCi TBD) fractionated dose administered 20mCi/m2 (~40mCi TBD) on days 1 and day 8. Cohort seven was the highest pre-planned dose cohort and subjects have completed the evaluation period. Adverse events occurring in at least 25% of subjects were fatigue (26%) and cytopenias, specifically, thrombocytopenia (90%), anemia (65%), neutropenia (55%), leukopenia (61%), and lymphopenia (58%). Serious adverse events occurring in greater than two subjects were restricted to febrile neutropenia n=3 (9.7%).

In May 2019, we announced that the FDA granted Fast Track Designation for iopofosine in fourth line or later r/r MM. Patients in the trial received up to four, approximately 20-minute, IV infusions of iopofosine over 3 months, with doses given 14 days apart in each cycle and a maximum of two cycles. Low dose dexamethasone 40 mg weekly (20mg in patients ≥ 75), was provided for up to 12 weeks. The planned trial enrollment was up to 80 patients. Its primary endpoint was clinical benefit rate (CBR), with additional endpoints of ORR, PFS, median overall survival (OS) and other markers of efficacy. Over the course of the trial the dosing regimen of iopofosine advanced from a single bolus dose to two cycles of fractionated administrations of 15 mCi/m2 per dose on days 1, 15 (cycle 1), and days 57, 71 (cycle 2). Following treatment with iopofosine, approximately 91% of patients experience a reduction in tumor marker with approximately 73% experiencing greater than 37% reduction.

CLOVER 2: Phase 1 Trial in r/r Pediatric Patients with select Solid tumors, Lymphomas and Malignant Brain Tumors

The Phase 1b portion of this trial was partially funded by a $1,900,000 National Cancer Institute (NCI) Small Business Innovation Research (SBIR) grant. In December 2017, the FDA's Division of Oncology accepted our IND trial design and in 2018, the FDA granted ODD and RPDD for iopofosine for the treatment of neuroblastoma, rhabdomyosarcoma, Ewing's sarcoma and osteosarcoma. The trial was initiated during the first quarter of 2019 and was conducted internationally at seven leading pediatric cancer centers.

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This Phase 1 trial evaluated iopofosine in children and adolescents with rare and orphan designated cancers including select solid tumors, lymphomas and malignant brain tumors. The Phase 1 clinical trial was an open-label, sequential-group, dose-escalation trial evaluating the safety and tolerability of intravenous administration of iopofosine in children and adolescents with relapsed or refractory malignant solid tumors (neuroblastoma, Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma) and lymphoma or recurrent or refractory malignant brain tumors for which there are no standard treatments. Secondary objectives of the trial were to identify the recommended efficacious dose of iopofosine and to determine preliminary antitumor activity (treatment response) of iopofosine in children and adolescents.

In August 2020, based on data on four dose levels from 15mCi/m2 up to 60mCi/m2, the iDMC permitted the beginning of the evaluation of the next higher dose cohort, at 75mCi/m2. The iDMC advised, based upon the initial data, to enrich the 60 mCi/m2 dose level for patients over the age of 10 with HGG and Ewing sarcoma. Changes in various tumor parameters appeared to demonstrate initial response and tumor uptake. This includes patients with relapsed HGGs with over five months of PFS. In November 2020, we announced and provided clinical data showing that iopofosine had been measured in pediatric brain tumors, confirming that systemic administration of iopofosine crosses the blood brain barrier and is delivered into tumors. In addition, data showed disease control in heavily pretreated patients with ependymomas. In November 2021, we announced favorable data on changes in various tumor parameters in a Phase 1 trial in children and adolescents with relapsed and refractory high-grade gliomas (HGGs) and soft tissue sarcomas. Pediatric HGGs are a collection of aggressive brain and central nervous system tumor subtypes (i.e. diffuse intrinsic pontine gliomas, glioblastomas, astrocytomas, ependymomas, etc.) with about 400 new pediatric cases diagnosed annually in the U.S. Children with these tumors have a poor prognosis and limited 5-year survival. Adverse events occurring in at least 25% of subjects were fatigue, headache, nausea and vomiting (28% respectively), and cytopenias, specifically, thrombocytopenia (67%), anemia (67%), neutropenia (61%), leukopenia (56%), and lymphopenia (33%). There were no serious adverse events occurring in more than 2 subjects. The part A portion of this Phase 1 trial was concluded with the maximum tolerated dose determined to be greater than 60mCi/m2 administered as a fractionated dose.

CLOVER-2 Phase 1b trial was an open-label, international dose-finding trial evaluating two different doses and dosing regiments of iopofosine in pediatric patients with r/r high-grade gliomas. These cancer types were selected for clinical, regulatory and commercial rationales, including the radiosensitive nature and continued unmet medical need in the r/r setting, and the rare disease determinations made by the FDA based upon the current definition within the Orphan Drug Act. The study is no longer enrolling patients.

Phase 1 Trial in r/r Head and Neck Cancer

In August 2016, the University of Wisconsin Carbone Cancer Center (UWCCC) was awarded a five-year Specialized Programs of Research Excellence (SPORE) grant of $12,000,000 from the NCI and the National Institute of Dental and Craniofacial Research to improve treatments and outcomes for head and neck cancer (HNC) patients. HNC is the sixth most common cancer across the world with approximately 56,000 new patients diagnosed every year in the U.S. As a key component of this grant, the UWCCC researchers completed testing of iopofosine in various animal HNC models and initiated the first human clinical trial enrolling up to 30 patients combining iopofosine and external beam radiation treatment (EBRT) with recurrent HNC in the fourth quarter of 2019. UWCCC has completed the part A portion of a safety and tolerability trial of iopofosine in combination with EBRT and preliminary data suggest safety and tolerability in relapsed or refractory HNC. The reduction in the amount or fractions (doses) of EBRT has the potential to diminish the (number and severity of) adverse events associated with EBRT. Patients with HNC typically receive approximately 60-70 Grays (Gy) of EBRT given as 2 - 3 Gy daily doses over a six-week timeframe. Patients can experience long-term tumor control following re-irradiation in this setting; however, this approach can cause severe injury to normal tissue structures, significant adverse events and diminished quality of life. Part B of the trial was to assess the safety and potential benefits of iopofosine in combination with EBRT in a cohort of up to 24 patients. This portion of the trial has fully enrolled, and data were reported at the ASTRO 2024 conference on March 2, 2024. Complete remission was achieved in 64% of patients, with an ORR of 73% (n=11). Prior to treatment with iopofosine I 131, six patients had multiple recurrences, and one had metastatic disease, both of which are indicative of poor outcomes. Additionally, in the trial we observed durability of tumor control with an overall survival of 73% and progression free survival of 36% at 12 months. Eleven patients (92%) experienced a treatment-related adverse event. Treatment-related adverse events of grade 3 or higher occurring in 20% or more patients were thrombocytopenia (75%), lymphopenia (75%), leukopenia (75%), neutropenia (67%), and anemia (42%). Observed adverse events were consistent with the known toxicity profile of iopofosine I 131, with cytopenias being the most common. All patients recovered. We believe that these data support the notion of enhanced patient outcomes when combining the use of iopofosine I 131 in combination with external beam radiation for a treatment of solid tumors.

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Clinical and Preclinical

CLR 121125 Clinical Trial

CLR 121125 (CLR 125), an iodine-125 Auger-emitting program, is currently in a Phase 1b dose finding clinical trial for TNBC. CLR 125 utilizes iodine-125 as its radiation source and has been observed to show tolerability with minimal toxicities in animal models. The Company observed CLR 125 to have good activity in multiple solid tumor models, particularly in triple negative breast cancer. Auger emitters provide the greatest precision in targeted radiotherapy as the emission only travels a few nanometers. The Company believes that for iodine-125 to be effective, the isotope must enter the cell and be close to the cell nucleus to affect the necessary breakage of tumor cell DNA. The Company believes that its novel phospholipid ether drug conjugate platform achieves this requirement with CLR 125. In preclinical in vivo evaluations of CLR 125 utilizing TNBC models, the compound was observed to have tumor uptake at a substantially higher rate than that of healthy tissue. Additionally, no signs of end-organ toxicity were observed including hematological toxicity. In April 2026, the Company subsequently initiated a Phase 1b clinical trial in TNBC. The trial objective is to determine the Phase 2 dosing level with secondary endpoints including safety, tolerability, initial response assessment and distribution. The trial is a randomized, open-label, multi-center trial designed to compare the safety and efficacy of CLR 125 in patients with advanced TNBC who are relapsed/refractory (r/r) to at least one prior therapy. Three dose levels will be assessed in parallel, with enrollment of patients in a 1:1:1 manner. If required, we expect that each arm will have a minimum of 15 evaluable patients. CLR 125 will be administered as a fractionated dose on Day 1 and Day 3 for cycle 1 and repeat approximately every eight weeks for subsequent cycles. Depending on arm assignments, patients will receive between two and four cycles. An expansion arm may consist of at least 15 patients following evaluation of the three dose levels by the data monitoring committee (DMC). If required, we plan to enroll up to a maximum of 75 patients. Safety and tolerability of CLR 125 will be assessed by physical examination, Eastern Cooperative Oncology Group (ECOG) performance status, vital signs and laboratory tests.

CLR 121225 Preclinical Evaluation

CLR 121225 (CLR 225), an actinium-225 based program is currently Phase 1 ready. CLR 225 has shown activity in multiple solid tumor animal models including pancreatic, colorectal and breast cancers. CLR 225 was well tolerated in these models with the animals showing no adverse events at the highest doses tested. The compound demonstrated excellent biodistribution and tumor uptake. Furthermore, in multiple models of pancreatic adenocarcinoma, including highly refractory pancreatic cancer, we have observed proportional dose response with a single dose of CLR 225 providing either tumor stasis at the lowest dose tested or tumor volume reduction at the higher doses. Survival benefit was observed at four different dosing levels. Observed biodistribution exhibited substantial uptake in the tumor while remaining low in healthy tissue. The Company is prepared to initiate a Phase 1 imaging and dose escalation safety trial subject to corporate strategy.

Additional Pipeline Candidates

We believe our PDC platform has potential to provide targeted delivery of a diverse range of oncologic payloads. Additional pipeline product candidates, described below, may also result in improvements to the current standard of care (SOC) for the treatment of a broad range of human cancers:

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Technology Overview: PDC Platform

Mechanism of Action

Our PDC platform is designed to provide selective delivery of a diverse range of oncologic payloads to cancerous cells, whether a hematologic cancer or solid tumor; a primary tumor, or a metastatic tumor; and cancer stem cells. The PDC platform's mechanism of entry is not designed to rely upon a specific cell surface epitope or antigen as are required by other targeted delivery platforms but rather a unique change in the tumor cell membrane. Our PDC platform takes advantage of a metabolic pathway (beta oxidation) utilized by nearly all tumor cell types in all stages of the tumor cycle. Tumor cells modify the cell membrane to create specific, highly organized microdomains by which to transport lipids and long chain fatty acids into the cytoplasm, as a result of the utilization of this metabolic pathway. Our PDCs are designed to bind to these regions and directly enter the intracellular compartment. This mechanism allows the PDC molecules to accumulate in tumor cells over time, which we believe can enhance drug efficacy. Direct intracellular delivery allows our molecules to avoid the specialized, highly acidic cellular compartment known as lysosomes, which allows a PDC to deliver payloads that previously could not be delivered in this targeted manner. Additionally, molecules targeting specific cell surface epitopes face challenges in completely eliminating a tumor because the targeted antigens are limited in the total number presented on the cell surface, limiting total potential uptake and resulting in heterogenous uptake across the tumor, have longer cycling time from internalization to relocation on the cell surface, again diminishing their availability for binding, and are not present on all of the tumor cells because of the heterogenous nature of cancer cells, further increasing the unequal distribution of the drug across the tumor. This means a subpopulation of tumor cells always exists that cannot be addressed by therapies targeting specific surface epitopes. Additionally, epitopes utilized are often present on normal tissue, resulting in on-target toxicities.

Beyond the benefits provided by the mechanism of entry, the PDC platform features include the capacity to link with almost any molecule, provide a significant increase in targeted oncologic payload delivery, a more uniform delivery and the ability to target all types of tumor cells. As a result, we believe that we can create PDCs to treat a broad range of cancers with the potential to improve the therapeutic index of oncologic drug payloads, enhance or maintain efficacy while also reducing adverse events by minimizing drug delivery to healthy cells, and increasing delivery to cancerous cells and cancer stem cells.

We employ a drug discovery and development approach that allows us to efficiently design, research and advance drug candidates. Our iterative process allows us to rapidly and systematically produce multiple generations of incrementally improved targeted drug candidates without the expense of having to generate significant compound libraries.

Products in Development

Phospholipid RadioConjugates (PRC's)

In parallel to advancing the clinical development of our lead PDCs in both adult and pediatric orphan indications, we remain focused on exploring the creation of additional PDCs ranging from newly discovered to well-characterized anti-cancer agent payloads. The objective is to develop PDC chemotherapeutics through conjugation of our delivery vehicle and non-targeted anti-cancer agents to improve therapeutic indices and expand potential indications through the targeted delivery of chemotherapeutic payloads. A number of non-radiotherapeutic treatment modalities, such as small-molecule, peptide, and oligonucleotide cancer-targeting chemotherapeutics, are in pre-clinical research. To date, multiple cancer-targeting product profiles have been generated from a single chemical core structure that is the foundation of our technology platform. We also believe that additional cytotoxic PDCs may be developed possessing enhanced therapeutic indices versus the original, non-targeted cytotoxic payload as a monotherapy.

Our product candidates are based on a cancer-targeting delivery platform of optimized phospholipid ether (PLE) analogs (phospholipid ether proprietary delivery vehicle) that interact with lipid rafts. Lipid rafts are specialized regions of a cell's membrane phospholipid bilayer that contain high concentrations of cholesterol and sphingolipids and serve to organize cell surface and intracellular signaling molecules. As a result of enrichment and stabilization of lipid rafts in cancer cells, including cancer stem cells, our product candidates provide selective targeting preferentially to cancer cells over normal healthy cells. The cancer-targeting PLE delivery vehicle was deliberately designed to be combined with therapeutic, diagnostic and imaging molecules.

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Tumor treatment with radioactive isotopes has been used as a fundamental cancer therapeutic for nearly a century. The goals of targeted cancer therapy - selective delivery of effective doses of isotopes that destroy tumor tissue, sparing of surrounding normal tissue, and non-accumulation in vital organs such as the liver and kidneys - remain goals of new therapies as well. We believe our targeted delivery technology has the potential to achieve these goals. Iopofosine has been shown in animal models and various clinical trials to reliably, and near-universally, accumulate in cancer cells including cancer stem cells. This strategy has allowed us to take a multi-indication approach in the development and potential commercialization of iopofosine. To date, we have focused on rare cancers with significant unmet need including WM, MM, sarcomas, and HGG, among others.

Financing

On May 5, 2026, the Company announced that it had entered into a securities purchase agreement with certain institutional investors, and an additional securities purchase agreement with certain members of management, to issue and sell an aggregate of approximately $35 million upfront and up to $105 million in milestone-based securities in a registered direct offering of common stock and a concurrent private placement of common stock, pre-funded warrants, and milestone-based warrants. The transactions closed on May 6, 2026, and resulted in net proceeds to the Company of approximately $31.7 million. The proceeds from this financing will be used for general corporate purposes, including to support the initiation of a Phase 3 confirmatory study of iopofosine I 131 for the treatment of WM patients.

Results of Operations

Research and development expenses. Research and development expenses consist of costs incurred in identifying, developing and testing, and manufacturing product candidates, which primarily include salaries and related expenses for personnel, cost of manufacturing materials and contract manufacturing fees paid to contract manufacturers and contract research organizations, and fees paid to medical institutions for clinical studies. The Company analyzes its research and development expenses based on four categories as follows: clinical project costs, preclinical project costs, manufacturing and related costs, and general research and development costs that are not allocated to the functional project costs, including personnel costs, facility costs and related overhead costs.

General and administrative expenses. General and administrative expenses consist primarily of salaries and other related costs for personnel in executive, finance and administrative functions. Other costs include insurance, costs for public company activities, investor relations, directors' fees and professional fees for legal and accounting services.

Other income (expense), net. Other income (expense), net, consists primarily of the impacts related to issuing and revaluing equity securities, and interest income.

Three Months Ended September 30, 2026 and 2025

Research and Development. Research and development expenses for the three months ended September 30, 2026, were approximately $5,436,000, compared to approximately $2,523,000 for the three months ended September 30, 2025.

The following table is a summary comparison of approximate research and development costs for the three months ended September 30, 2026 and 2025:

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The overall increase in research and development expense was approximately $2,913,000, or 115%. The increase in spending was composed primarily of increased clinical project costs and manufacturing and related costs resulting from the initiation of activities relating to our Phase 3 confirmatory trial of iopofosine I 131 in WM and increased spending for our Phase 1b trial of CLR 125 in TNBC, offset in part by reduced activity in our pediatric study in high-grade glioma.

General and administrative. General and administrative expense for the three months ended September 30, 2026, was approximately $2,668,000, compared to approximately $2,327,000 for the same period in 2025. The overall increase in general and administrative expense of approximately $341,000, or 15%, was driven by costs associated with an increase in professional fees and personnel costs.

Other income (expense), net. Other income (expense), net, for the three months ended September 30, 2026, was approximately $129,000, as compared to approximately $407,000 in the same period of 2025, resulting almost exclusively from changes in warrant valuation, which are non-cash in nature, and are primarily impacted by fluctuations in the Company's common stock price. Interest income increased year-over-year to approximately $179,000 in 2026 as compared to approximately $113,000 in the three months ended September 30, 2025. The Company's higher amounts of invested funds drove the increase.

Nine Months Ended September 30, 2026 and 2025

Research and Development. Research and development expenses for the nine months ended September 30, 2026, were approximately $13,000,000, compared to approximately $8,340,000 for the nine months ended September 30, 2025.

The following table is a summary comparison of approximate research and development costs for the nine months ended September 30, 2026 and 2025:

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The overall increase in research and development expense of approximately $4,660,000, or 56%, was primarily a result of increased clinical project costs and manufacturing and related costs of approximately $4,441,000 and $780,000, respectively, resulting from the initiation of our activities relating to our Phase 3 confirmatory trial of iopofosine I 131 in WM and our Phase 1b trial of CLR 125 in TNBC, offset in part by decreased pre-clinical project costs of approximately $479,000, driven by reduced activity in our pediatric study in high-grade glioma.

General and administrative. General and administrative expense for the nine months ended September 30, 2026, was approximately $8,094,000, compared to approximately $8,949,000 for the same period in 2025. The overall decrease in general and administrative expense of approximately $855,000, or 10%, was driven by decreases in professional fees, pre-commercialization activities and personnel costs.

Other income (expense), net. Other income (expense), net, for the nine months ended September 30, 2026, was approximately $535,000, as compared to approximately $793,000 of income in the same period of 2025, resulting from changes in warrant valuation and interest income. The changes in warrant valuation impacts are non-cash in nature and are largely driven by fluctuations in the Company's common stock price. Interest income increased to approximately $376,000 in the nine months ended September 30, 2026, as compared to approximately $338,000 for the same period in 2025. Higher average amounts of invested funds in the current year were the primary driver of the increase.

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Liquidity and Capital Resources

We have incurred losses since inception in devoting substantially all of our efforts toward research and development of drug candidates for which we are seeking FDA approval. During the nine months ended September 30, 2026, we generated a net loss of approximately $20.6 million and used approximately $20.3 million in cash for operations. We expect that we will continue to generate operating losses for the foreseeable future. As of September 30, 2026, our consolidated cash balance was approximately $25.0 million. As of the date the accompanying consolidated financial statements were issued (the "issuance date"), the Company's available liquidity to fund the Company's operations over the next twelve months beyond the issuance date was limited to approximately $21 million of unrestricted cash and cash equivalents. Absent further action taken by management to increase its liquidity, the Company may be unable to fund its operations under normal course beyond the second quarter of 2027. To improve the Company's liquidity, management plans to secure additional outside capital via the sale of equity and/or debt securities or execute a strategic transaction. Management also plans to preserve liquidity, as needed, by implementing temporary cost saving measures. While management believes their plans will be successful, no assurance can be provided such plans will be effectively implemented over the next twelve months beyond the issuance date. In the event management's plans are not effectively implemented, the Company will be required to seek other alternatives which may include, among others, strategic alternatives such as mergers, acquisitions, partnerships, joint ventures, licensing arrangements or other strategic transactions, the sale of assets, discontinuance of certain operations, and/or filing for bankruptcy protection.

These uncertainties raise substantial doubt about the Company's ability to continue as a going concern. The accompanying financial statements have been prepared on the basis that the Company will continue to operate as a going concern, which contemplates it will be able to realize assets and settle liabilities and commitments in the normal course of business for the foreseeable future. Accordingly, the accompanying consolidated financial statements do not include any adjustments that may result from the outcome of these uncertainties.

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