ViroMissile Shares Phase 1 Data on Oncolytic Virus in Hard-to-Treat Metastatic Colorectal Cancer

A first-in-class treatment is showing promise in one of the toughest diseases to treat: proficient mismatch repair/microsatellite stable (pMMR/MSS) metastatic colorectal cancer (mCRC).

La Jolla, California–based ViroMissile, Inc, brought its first clinical data to the 2026 American Society of Clinical Oncology Annual Meeting, presenting results from an investigator-initiated phase 1 study of IDOV-Safe,an intravenously deliverable oncolytic vaccinia virus, which is designed to prime the tumor for a second wave of drugs that zero in on the cancer.^1,2

The data, featured in a poster session, drew attention for what the company describes as a long-elusive technical achievement: true systemic delivery of an oncolytic virus. Most oncolytic virus programs have had to pivot to intratumoral injection because proteins that rapidly bind and neutralize viruses in the bloodstream make intravenous dosing ineffective. This can present practical challenges if metastatic disease is widespread, as can occur with mCRC.

In an interview with The American Journal of Managed Care®, ViroMissile Chief Operating Officer Mark Bertagnolli explained that this challenge is solved with the platform virus, which produces an unusually high proportion of extracellular enveloped virions (EEVs). “Normally, it’s 1% to 2% EEV. Ours is 60%. That’s the reason why it leaks out faster, that’s the reason why we’re able to infect the tumor before the immune system comes in, and that’s the reason why it can survive in the blood. There’s no voodoo, no magic, no hand-waving.”

The phase 1 trial (NCT06380309) enrolled 55 patients with pMMR/MSS mCRC who had progressed on at least 2 prior lines of therapy; 80% had failed 3 or more lines. IDOV-Safe was tested as monotherapy in dose escalation, then in combination with the VEGF inhibitor fruquintinib (Fruzaqla; Takeda) and the PD-1 inhibitor toripalimab (Loqtorzi; Coherus Oncology) across sequential, early, and immuno-oncology-free expansion cohorts.

The rationale reflects the virus’ proposed mechanism: Infecting tumors converts immunologically “cold” tumors to “hot” ones, potentially sensitizing them to checkpoint inhibition. “We turned the cold tumor hot,” Bertagnolli said. “Now PD-1 inhibitors should work, and that’s what we’re seeing.”

Results from the key expansion cohort (IIA2; n = 20) showed an objective response rate (ORR) of 30% and a disease control rate of 70%, with a median progression-free survival (PFS) of 8.7 months. Data from the poster presentation showed the signal sharpened considerably in patients without liver metastases: ORR reached 46.2%, and median PFS extended to 10.8 months. Grade 3 or higher treatment-related adverse events occurred in 62% of patients, most commonly transient fever, thrombocytopenia, and neutropenia. There were no treatment-related deaths.²

Fever, which is a sign of immune activation, was described as expected and manageable. “Virtually any grade 3 adverse event is transient,” Bertagnolli said. “The doctors don’t treat it, because it’s just an immediate response to our therapy, and then it fades.”

The study was conducted at Peking University Cancer Hospital & Institute in Beijing, China, where investigators enrolled 40 to 50 patients in roughly 12 months, a pace that would be difficult to achieve in the United States. Bertagnolli said Peking University is “top shelf” and that the FDA appears receptive to data from China when studies are conducted rigorously at top universities. A phase 2 study in the United States is now under consideration, and a discussion about design with the FDA is planned, he said.

References

1. ViroMissile IDOV-Safe phase 1 data to be presented at the 2026 ASCO annual meeting. News release. ViroMissile, Inc. May 27, 2026. June 24, 2026. https://finance.yahoo.com/sectors/healthcare/articles/viromissile-idov-safe-phase-1-120000338.html
2. Xie T, Xu T, Wang Z, et al. Intravenous oncolytic virus IDOV-Safe in pMMR/MSS metastatic colorectal cancer. J Clin Oncol. 2026;44(suppl 16):3536. doi:10.1200/JCO.2026.44.16_suppl.3536