At Sylvester Comprehensive Cancer Center in Miami, researchers are testing a bold new approach to a disease that has long frustrated oncologists: combining a tumor-targeting virus with immunotherapy to fight high-grade neuroendocrine tumors, cancers so aggressive and treatment-resistant that standard chemotherapy often remains patients' only option.
The Phase I clinical trial pairs two immunotherapy drugs—nivolumab and ipilimumab—with Seneca Valley virus (SVV-001), a virus engineered to selectively grow inside tumors. The strategy addresses a fundamental problem: many high-grade neuroendocrine tumors have learned to hide from the immune system, evading recognition in ways that render checkpoint inhibitors ineffective. SVV-001 works differently. By infecting tumor cells and disrupting them from within, the virus may expose cancer-specific molecules that immune cells can finally recognize and attack.
"Immunotherapy has revolutionized cancer treatment," said Chinmay Jani, M.D., Sylvester's chief fellow in hematology and oncology, who presented early findings at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. "But it still has a lot of issues, including resistance, and many patients are non-responders. This trial is about improving immunotherapy."
The research team identified a crucial piece of the puzzle: a biomarker called tumor endothelial marker 8 (TEM8), which appears on cancer cells but not on healthy tissue in the lungs, ovaries, pancreas, stomach, uterus, breast, or colon. SVV-001 targets this marker with precision, allowing the therapy to attack the most aggressive cancer cells while leaving normal cells untouched. In patients whose tumors express TEM8, outcomes are typically poor—the marker drives tumor aggressiveness and metastasis—making it an ideal target for this new approach.
The trial launched in 2025 and has already completed three dose levels, a significant milestone for early-stage research. What's particularly encouraging: no severe treatment-related side effects have been reported so far, a critical safety signal in experimental cancer therapy. In the current phase, patients received a single dose of SVV-001 followed by immunotherapy. The next phase will escalate to up to six doses of SVV-001 injections, followed by immunotherapy, allowing researchers to identify the optimal treatment regimen before expanding enrollment.
"Many tumors evade immune detection; this study evaluates whether SVV-001 can expose cancer cells and enhance the effectiveness of checkpoint inhibitors," said Gilberto Lopes, M.D., Sylvester's chief of medical oncology. Researchers are using next-generation sequencing to track how TEM8 expression levels influence outcomes, layering molecular insights onto clinical data.
High-grade neuroendocrine cancer is rare and has historically attracted limited research investment, leaving patients with few options. This trial represents a shift—a willingness to combine established immunotherapies in novel ways and pair them with cutting-edge viral engineering. The early data are modest but real: safety, tolerability, and a plausible biological mechanism all pointing in promising directions.
Researchers continue enrolling patients as the trial advances, moving toward a clearer picture of whether this combination can finally deliver for patients whose cancers have resisted conventional approaches. In the world of rare cancers, such cautious, science-driven optimism can make all the difference.