On May 27, 2026 ViroMissile, Inc., a cancer immunotherapy company pioneering the IDOV (Intravenously Deliverable Oncolytic Virus) platform, reported the presentation of clinical data from an investigator-initiated Phase I study of IDOV-Safe, the company’s first clinical-stage oncolytic virus, at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting in Chicago, Illinois.
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The poster, titled "Intravenous oncolytic virus IDOV-Safe in pMMR/MSS metastatic colorectal cancer" (Abstract #3536), will be presented on Saturday, May 30th, at Poster Board 290 by Tong Xie, MD, of Peking University Cancer Hospital & Institute in Beijing, China. The study’s principal investigator is Lin Shen, MD, of the same institution.
"These findings validate a core hypothesis underlying our IDOV platform that systemic delivery of an oncolytic virus can prime immune responses even in tumors historically considered immune-cold," said Nanhai George Chen, PhD, Founder and Chief Executive Officer of ViroMissile. "Achieving a 30-46% response rate in pMMR/MSS metastatic colorectal cancer, a setting where checkpoint inhibitors have largely fallen short, represents an encouraging signal that warrants further investigation. We look forward to advancing this approach into our contemplated registrational Phase 2 study."
The data are from a study evaluating IDOV-Safe in combination with fruquintinib, a VEGF inhibitor, and toripalimab, a PD-1 inhibitor, in patients (n=55) with proficient mismatch repair/microsatellite stable (pMMR/MSS) metastatic colorectal cancer (mCRC). Patients with mCRC historically have limited treatment options and poor response to checkpoint inhibitor-based immunotherapy. The poster highlights results from a key expansion cohort (n=20) where treatment with IDOV-Safe demonstrated an objective response rate (ORR) of 30.0% and a disease control rate (DCR) of 70.0%, with a median progression-free survival (PFS) of 8.7 months. In patients without liver metastases, ORR reached 46.2% and median PFS extended to 10.8 months.
Study Design
The investigator-initiated Phase I trial treated a total 55 patients with pMMR/MSS mCRC across all cohorts. The study employed a triplet 3+3 dose-escalation design to assess dose-limiting toxicities (DLTs) and determine the maximum tolerated dose and the recommended expansion dose. Expansion cohorts assessed IDOV-Safe in combination with fruquintinib and with or without toripalimab across three combination strategies: sequential, early, and IO-free. Primary and secondary endpoints included safety, objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS).
Key findings
Safety
IDOV-Safe demonstrated a manageable safety profile across all dose levels
62% of patients experienced Grade 3 or higher treatment-related adverse events (TRAEs), with only one Grade 4 TRAE reported as a dose-limiting toxicity (DLT). The most common TRAEs were transient fever, thrombocytopenia, and neutropenia
No treatment-related deaths were observed
Efficacy/Tumor Response
In the sequential combination expansion cohort, which received IDOV-Safe at the higher dose level in combination with fruquintinib and toripalimab, the results demonstrated:
An objective response rate (ORR) of 30.0% was observed overall in the key expansion cohort
In patients without liver metastases, ORR reached 46.2% with a DCR of 84.7% and a median PFS of 10.8 months, compared to a median PFS of 3.7 months in patients with liver metastases
Median progression-free survival (PFS) was 8.7 months overall.
The poster will be available on the ViroMissile website after the conclusion of the session.
(Press release, ViroMissile, MAY 27, 2026, View Source [SID1234666104])