Intravenous infusion (IV) or intracavitary perfusion (IP) of T3011, an oncolytic HSV expressing IL-12 and PD-1 antibody: Analyses of two phase 1 studies.

e14581 Background: T3011 is a recombinant HSV-1 oncolytic virus expressing both IL-12 and anti-human PD-1 antibody. Upon delivery, locally produced IL-12 and PD-1 induces IFN-γ production, enhances the oncolytic activity of NK cells and cytotoxic T lymphocytes, promotes anti-angiogenesis, and inhibits tumor growth. We present the results of T3011 monotherapy administered via IV in advanced solid tumors or IP for malignant pleural effusion/ascites. Methods: In a phase 1, dose-escalation and expansion study using a 3+3 design with 5 cohorts (1×106, 1×107, 1×108, 5×108, 1×109 PFU), T3011 was administered intravenously on Days 1, 4, 8, 11,15,18 of a 28-day cycle in pts with advanced solid tumors. The primary objective was to evaluate the safety and tolerability of IV T3011, characterize dose-limiting toxicities (DLTs), MTD or RP2D, pharmacokinetic and pharmacodynamic profiles. In another pilot study to evaluate the safety and efficacy of T3011 in pts with malignant pleural effusion or ascites, T3011 was infused into the pleural or peritoneal cavity through an indwelling catheter on Days 1, 4, 8, 11 with 2 cohorts (5×108, 2×109 PFU). The response of malignant pleural effusion or ascites was assessed by WHO criteria. Results: As of 15 Dec 2023, 18 pts were enrolled and treated with IV T3011,4 pts received IV T3011 therapy at the highest dose level, 1×109 PFU. T3011 was well tolerated without ≥ Grade 3 TRAEs or DLTs. MTD was not reached. The most common TRAEs (≥ 10%) were nausea and infusion-related reactions, diarrhea, etc. Among 14 evaluable pts with advanced solid tumors, 3 pts had confirmed SD per RECIST1.1 and tumor burden reduced significantly. All the pts had detectable T3011 DNA in blood within 0.5-2 hours after administration, which was cleared subsequently within 3-7 days. As of 5 Jan 2024, 6 pts (pleural effusion 3, ascites 3) were dosed with IP T3011. 2 pts received 5×108 PFU and 4 pts received 2×109 PFU. Most TEAEs were grade 1 or 2. Only 1 pt developed grade 3 leukopenia, which resolved with G-CSF. No SAE occurred. 3 pts with pleural effusion showed 1 CR, 1 PR and 1 SD. 3 pts with malignant ascites secondary to advanced colorectal cancer, 1 was evaluable with PR. Conclusions: IV T3011 monotherapy has a very manageable safety profile and some encouraging activity in advanced solid tumors. IP T3011 monotherapy is also well tolerated and demonstrates promising activity against malignant pleural effusion and ascites. Clinical trial information: NCT04780217 .