Oncolytic Virus Shows 42% Response in Solid Tumors
Early STEALTH-001 trial data presented at the 2026 SITC Annual Meeting report responses in patients with advanced solid tumors treated with intratumoral VET3-TGI.
Updated on Nov. 7, 2026 in Cancer
Data presented at the 2026 SITC Annual Meeting showed that the oncolytic vaccinia virus VET3-TGI produced responses in patients with advanced solid tumors. Among 12 evaluable patients, the objective response rate was 42% by blinded independent central review.
Why it matters
The results add early clinical evidence for intratumoral oncolytic virus therapy, particularly in cutaneous malignancies that had progressed on prior anti-PD-1 or PD-L1 treatment. The program is now focusing on cutaneous cancers, where the response signal was strongest.
The figures come from the early phase 1/1b STEALTH-001 trial, which enrolled 20 patients as of a September 2026 cutoff, with 12 evaluable for efficacy. The 42% overall response rate rose to 71% in the cutaneous subgroup, but the sample sizes are too small to establish durable benefit.
The players
University of Pittsburgh Medical Center Hillman Cancer Center
A major academic cancer center whose affiliated physician presented the STEALTH-001 data.
The details
VET3-TGI is an oncolytic vaccinia virus encoding a TGF-β inhibitor and interleukin-12, administered intratumorally alone or with atezolizumab. Sixteen patients received monotherapy and four received the combination, and responses were also seen in non-injected lesions.
Timeline
September 2026: Data cutoff for 20 treated patients.
2026 SITC Annual Meeting: Presentation of STEALTH-001 efficacy data.
Health Landscape
Oncolytic viruses that deliver immune-activating payloads such as interleukin-12 are being tested as a way to reach tumors that resist checkpoint inhibitors alone. The VET3-TGI program is one of several efforts exploring whether local viral therapy can complement existing anti-PD-1 and PD-L1 treatments.
For patients with advanced skin cancers that have progressed on checkpoint inhibitors, this early work points to a possible local treatment option still in clinical testing. The therapy is not yet available outside of research studies, and benefit has not been confirmed in larger trials.
The takeaway
Early responses in hard-to-treat cutaneous cancers suggest intratumoral viral therapy deserves further study. Patients interested in trial participation should discuss eligibility with their oncology team.
Further reading
Explore more Cancer coverage on Wisevoter.
Source note: This article includes information reported by OncLive.
