Oncolytic virus CF33-hNIS monotherapy for the treatment of gastrointestinal (GI) malignancies.
Authors: Daneng Li, Anthony F. Shields, Hirva Mamdani, Jennifer Leddon, Patrick M. Travis, Colt A. Egelston, Oscar Colunga Flores, Stanley R. Hamilton, Janet Austria, Amanda Seiz, Sharon Yavrom, John Chong Han Byon, Paul Paul Woodard, Grey A Wilkinson
Journal: Journal of Clinical Oncology (2024)

749 Background: CF33-hNIS is a novel chimeric DNA vaccinia virus engineered with the human sodium-iodide symporter (hNIS) gene. CF33-hNIS selectively replicates in tumor cells leading to cell lysis and the release of tumor- and virus-associated antigens stimulating antitumor immunity. Here, we report results of patients with GI malignancies enrolled on a first-in-human phase 1 ascending, multiple dose, safety and tolerability study of CF33-hNIS, administered intratumorally (IT) or intravenously (IV) in adult patients with metastatic or advanced solid tumors (MAST). Methods: The MAST study is evaluating the safety of CF33-hNIS administered IT or IV, alone or in combination with pembrolizumab in patients with advanced or metastatic solid tumors with ≥ 2 prior lines of therapy (NCT05346484). CF33-hNIS is administered in 21-day cycles on C1D1 and C1D8, then D1 of each cycle thereafter. Pembrolizumab begins C2D1 for the combination groups and is administered Q3W. The co-primary endpoints are safety and to identify the recommended phase 2 dose. Secondary endpoints include objective response rate according to RECIST v1.1 and iRECIST, and to assess levels of viral replication via Single-Photon Emission Computerized Tomography (SPECT) with technetium-99. Results: As of Aug 2023, we report early results from seven patients with GI malignancies who received CF33-hNIS alone, including: colorectal cancer (3), bile duct (2), pancreatic (1) and hepatocellular carcinoma (1). The disease control rate is 86%. Notably one patient with cholangiocarcinoma, treated IT with 3.0x10 7 PFU, presented with pseudoprogression with a 49% increase in tumor burden after two cycles of therapy. By the 4 th cycle they achieved a complete response (CR) with no known recurrence. A second patient with bile duct cancer, who previously progressed on checkpoint blockade therapy, achieved stable disease for &gt;5 months upon receiving IV-administered CF33-hNIS (3.0x10 7 PFU). Treatment-related adverse events for the CR patient included grade 1 fever and injection site reaction. All other patients experienced no treatment-related adverse events. SPECT analysis of the CR patient reveals intense levels of viral replication within the injected lesion and a concomitant increase in Th1 cytokines in cycle three that coordinated with tumor reduction. In-depth immunological changes in peripheral blood and on-treatment tumor biopsies will be presented. Conclusions: CF33-hNIS can replicate within cholangiocarcinoma lesions, as shown by SPECT imaging, and drive immunological changes known to promote antitumor immunity. CF33-hNIS monotherapy may be an effective and safe treatment option for GI malignancies, including cholangiocarcinoma, a rare disease with an unmet medical need. Treatment with CF33-hNIS monotherapy was well tolerated and the study has advanced to examine combination therapy with pembrolizumab. Clinical trial information: NCT05346484 .