Entolimod Enters Mouse Efficacy Testing for Radiation
The research-stage drug is being tested for survival in mice, with results expected in early December 2026.
Updated on Nov. 2, 2026 in Biotech
Valion Bio, a clinical-stage biopharmaceutical company, is advancing its drug candidate Entolimod into a therapeutic efficacy study at the Armed Forces Radiobiology Research Institute (AFRRI). The study, fully funded by NIAID's Radiation and Nuclear Countermeasures Program, is at the research stage and tests Entolimod as a potential medical countermeasure for acute radiation syndrome.
Why it matters
The move to a therapeutic-phase study came days after Valion announced positive safety results, signaling the program is moving from safety toward efficacy testing. It reflects federal investment in countermeasures against radiation injury, a niche where few approved treatments exist.
The study's primary endpoint is survival over 30 days, compared between mice receiving a single dose of Entolimod and those receiving saline control. The partial-body model, which shields about 2.5% of bone marrow, is designed to reflect the marrow-sparing conditions the drug would need to address, though no efficacy figures have been reported yet.
The players
Valion Bio
A clinical-stage biopharmaceutical company developing Entolimod as a medical countermeasure for acute radiation syndrome.
Armed Forces Radiobiology Research Institute (AFRRI)
A federal research institute within the Uniformed Services University that evaluates radiation countermeasures, including the therapeutic efficacy of Entolimod.
National Institute of Allergy and Infectious Diseases (NIAID)
The NIH institute that fully funds the study through its Radiation and Nuclear Countermeasures Program.
The details
Entolimod is being developed as a potential treatment for acute radiation syndrome, a condition caused by high-dose radiation exposure that damages rapidly dividing cells such as those in bone marrow. In the study, mice are exposed to radiation in a partial-body model that leaves about 2.5% of their bone marrow shielded, which helps researchers assess whether a treatment can support survival when most marrow is damaged. Twenty-four hours after exposure, the animals receive one administration of either Entolimod or a saline control, and they are then monitored for 30 days.
Timeline
Valion Bio announced positive Entolimod safety results days before the efficacy study was announced.
November 2, 2026: Valion Bio announced the AFRRI therapeutic efficacy evaluation.
Early December 2026: Top-line results of the therapeutic study are anticipated.
The Tech Race
The study sits within the federal Radiation and Nuclear Countermeasures Program run by NIAID, which funds efforts to develop treatments for radiation injury. Entolimod's progress from safety results into a therapeutic efficacy study places it among the candidates the program is evaluating, though the stub does not compare it with named competing drugs.
This is preclinical work in mice, so the drug is not available to patients and no timeline for human use has been announced. Its near-term relevance is to researchers and to any future clinical program that would follow if efficacy results are positive.
The takeaway
The key trajectory question is whether Entolimod's safety data translates into a survival benefit in this irradiation model. Watch for the top-line survival results expected in early December 2026, which will either support or weaken its case as a countermeasure for acute radiation syndrome.
What happens next
Top-line results from the therapeutic efficacy study are anticipated in early December 2026, which will show whether Entolimod improves survival in the mouse model.
Further reading
For the broader research context, see our Biotech coverage of drug development and clinical trials.
