Safety and efficacy of intratumourally administered INT230-6 in adult patients with advanced solid tumours: results from an open-label phase 1/2 dose escalation study

Background: Systemic chemotherapeutics have limited efficacy in many advanced solid tumours. This study evaluated the safety and tolerability of INT230-6, a unique intratumoural (IT) formulation of cisplatin, vinblastine, and 8-((2-hydroxybenzoyl)amino)octanoate (SHAO), an amphiphilic cell-penetration enhancer. Methods: In this single-arm phase 1/2 trial (NCT03058289), adults with advanced or metastatic disease who progressed on a median of three prior therapies received multiple doses of IT INT230-6 monotherapy once every 28 days or biweekly for five treatments with maintenance dosing every 9 weeks. INT230-6 dose was based on tumour diameter or volume and escalated across five cohorts. A fixed-dose cohort received up to 175 mL. Findings: No dose-limiting toxicities were reported among 64 enrolled patients; seven (10·9%) discontinued treatment due to adverse events (AEs). Overall, 52/64 (81·3%) patients had treatment-related AEs (TRAEs), including grade ≥3 TRAEs (7/64 [10·9%]) and serious TRAEs (3/64 [4·7%]). INT230-6 achieved a disease control rate (DCR) of 75% (48/64 patients) and median overall survival (mOS) of 11·9 months (95% confidence interval [CI]: 6·3–19·4). In an exploratory analysis, patients dosed at ≥40% of total tumour burden vs <40% had improved DCR (40/48 [83·3%] vs 8/16 [50%]) and mOS (18·7 months [95% CI: 11·5–23·5] vs 3·1 months [95% CI: 1·6–5·9]). Fifteen patients survived ≥21 months; eight were alive at study end. INT230-6 induced a qualitative decrease in proliferating cancer cells in injected tumours and a qualitative increase in activated T-cells infiltrating the tumour microenvironment. Ten patients had abscopal responses. Interpretation: IT INT230-6 was well tolerated and manifested promising treatment benefits. Funding: Intensity Therapeutics, Inc.