The Children's Tumor Foundation
08/19/2026 | Press release | Distributed by Public on 08/19/2026 14:51
Can Existing HIV Drugs Become a Treatment for NF2-SWN
Developing a new drug can take years. But sometimes, a potential treatment may already exist. The challenge is finding it.
Drug repurposing, identifying existing medicines that could work in new ways against NF tumors, is an important part of the Children's Tumor Foundation's strategy to accelerate treatments for people living with NF. Because these drugs have already been developed and studied in people, researchers can build on what is already known about their safety and use, potentially shortening the path from scientific discovery to clinical testing.
That strategy is at the heart of RETREAT, a CTF-funded clinical trial led by Professor C. Oliver Hanemann of the University of Plymouth, investigating whether two drugs originally developed to treat HIV could be a treatment for tumors associated with NF2-related schwannomatosis (NF2-SWN).
The protocol for the trial has now been published in the peer-reviewed journal BMJ Open, providing a closer look at the science behind RETREAT and the innovative way researchers are testing this potential treatment. Read the protocol publication here.
From HIV treatment to NF2-SWN
The two drugs being studied, ritonavir and lopinavir, are antiviral medications that have long been used to treat HIV.
So why test them in NF2-SWN?
Research from Hanemann and his team found unusually high levels of proteins from a type of human endogenous retrovirus called HERV-K in schwannomas and meningiomas that lack the tumor suppressor protein Merlin. Loss of Merlin, which is produced by the NF2 gene, is central to the development of NF2-related tumors.
In laboratory studies using human schwannoma and meningioma cells, ritonavir and lopinavir reduced levels of these retroviral proteins and reduced tumor cell proliferation.
That provided researchers with an intriguing question: Could drugs we already know how to use in people be repurposed to interfere with a biological process involved in NF2-related tumor growth?
With funding from CTF, the RETREAT trial is taking the next step toward answering it.
A different kind of clinical trial
RETREAT is a Phase 0 clinical trial, an early-stage study designed to answer a very specific question before exposing larger numbers of patients to an experimental treatment:
Do the drugs reach the tumor and have the biological effect researchers expect them to have?
The study is enrolling up to 16 people with NF2-SWN at two sites in the United Kingdom. Participants receive ritonavir and lopinavir for 30 days, followed by another 30 days of follow-up.
Researchers collect blood samples and biopsies before and after treatment to determine how much of the drugs reach the tumor and whether they affect biological markers associated with tumor cell growth.
At this stage, researchers are not trying to demonstrate that the treatment shrinks tumors or improves symptoms. Instead, RETREAT is designed to provide evidence that the drugs are reaching their target and changing tumor biology in people with NF2-SWN.
If they are, that evidence could provide the foundation for larger studies designed to determine whether the treatment provides clinical benefit.
Using accessible tumors to answer a difficult question
One aspect of RETREAT is how researchers are looking for that evidence.
Many tumors associated with NF2-SWN occur in locations where taking repeated biopsies would be difficult and potentially harmful. But many people with NF2-SWN also develop cutaneous or subcutaneous schwannomas, tumors located in or just beneath the skin.
These tumors are much more accessible.
Researchers can biopsy one of these schwannomas before treatment and again after 30 days, allowing them to compare the tumor's biological activity before and after exposure to the drugs. This approach allows researchers to gather important information about whether the treatment is reaching NF2-related tumor tissue while limiting the invasiveness of the procedure.
Finding faster paths to treatments
For a rare disease like NF2-SWN, every opportunity to make drug development faster and more efficient matters.
Drug repurposing is one way CTF is working to do that.
Instead of starting with a completely new molecule, researchers look across existing drugs and ask whether their known biological effects could be useful against NF tumors. Existing drugs come with years of knowledge about how they behave in the human body, how they are administered, and what side effects they may cause.
That doesn't mean a repurposed drug will work for NF, and RETREAT is still an early-stage trial. But it can give researchers a valuable head start.
RETREAT also shows how CTF investment can help move an idea along the path from laboratory discovery toward patients: identifying a promising biological target, finding existing drugs that may act on it, and designing an efficient clinical trial to determine whether the approach is worth pursuing further.
For people living with NF2-SWN who still have limited treatment options, exploring every promising path matters. Sometimes, the next NF treatment may begin with a drug developed for something entirely different.
NF2-SWN patients interested in participating in this trial can learn more here.
Read the research
The RETREAT trial protocol, "Repurposing anti-retroviral drugs to treat NF2-related tumours: a protocol for a phase 0 trial (RETREAT)," was published in BMJ Open in June 2026.
RETREAT is supported by the Children's Tumor Foundation, Award 2023-04-002.
The Children's Tumor Foundation published this content on August 19, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on August 19, 2026 at 20:51 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]