Phase 1/2 Study of Intratumoral Injection of STX-001 in Advanced Solid Tumors as Monotherapy or in Combination With Pembrolizumab

This open-label, Phase 1/2, first-in-human (FIH), multiple ascending dose and dose expansion study involves STX-001 administration, alone or in combination with pembrolizumab, to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary antitumor activity in patients with advanced cancers. Phase 1 consists of 4 planned dose escalation cohorts of STX-001 delivered as a monotherapy (Cohorts 1m), 4 planned dose escalation monotherapy cohorts of STX-001 delivered as a combination therapy with pembrolizumab treatment given concurrently (Cohorts 1c), and an additional monotherapy cohort targeting visceral lesions (Cohort 1vm) that will be evaluated at 30ug, 100ug and 300ug. New patients will be enrolled in each dose escalation cohort. Phase 2 consists of dose expansion cohorts in patients with 2 defined cancer types: triple-negative breast cancer (TNBC) and melanoma. There will also be a monotherapy cohort for advanced melanoma. Phase 2 will evaluate STX-001 in combination with pembrolizumab; the recommended Phase 2 dose (RP2D) will be selected based on analysis of the totality of data from Phase 1 safety, tolerability, PK, PD and preliminary efficacy data.