Phase 1 and phase 2a, first-in-human (FIH) study, of DRP-104, a broad glutamine antagonist, in adult patients with advanced solid tumors.

TPS3149 Background: Dependence of cancer cells on glutamine has made glutaminolysis an attractive therapeutic target in cancer. Prior clinical trials evaluating glutamine analogues for the treatment of cancer were abandoned due to lack of efficacy and/or tolerability. DON (6-Diazo-5-oxo-L-norleucine) is an irreversible inhibitor of several enzymes that utilize glutamine as a metabolic substrate. In addition to direct anti-tumor efficacy, inhibition of glutamine metabolism in the tumor microenvironment has been shown to improve T-cell activation and tumor infiltration, increasing anti-tumor immune responses. As such, combining DON with an immune checkpoint inhibitor (ICI), has strong preclinical rationale. The investigational product DRP-104 (sirpiglenastat) is an inactive prodrug of DON designed to limit systemic DON exposure while targeting glutamine dependence in tumor cells. Methods: A phase 1/2a, FIH, multi-center, non-randomized, multi-cohort, open-label study of DRP-104 is currently open to accrual for patients with advanced solid tumors. This study will be conducted in 4 parts: A) Dose Escalation of IV and subQ DRP-104 (Run-In phase followed by modified Continual Reassessment Method) to define MTD/RP2D. Primary objective of dose escalation is to assess the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity of DRP-104 as a single agent; B) Dose Expansion of IV and subQ DRP-104 for safety assessment while primary objective is to select and recommend phase 2 DRP-104 route of administration; C) Phase 2a at recommended MTD/RP2D of selected route of DRP-104 in 2 patient cohorts: patients with locally advanced/metastatic NSCLC with KEAP1, NFE2L2 and/or STK11 mutation and patients with unresectable or metastatic SCCHN, in order to assess the safety, tolerability and preliminary antitumor activity of DRP-104 as a single agent; D) Phase 2a at recommended MTD/RP2D of selected route of DRP-104 in combination with atezolizumab in adult patients with advanced solid tumors previously treated with an ICI, in order to assess the safety, tolerability and preliminary antitumor activity of DRP-104 in combination with atezolizumab; DRP-104 IV is infused TIW over 1 hour infusion for 2 consecutive weeks followed by 1 week off. DRP-104 subQ is administered BIW weekly. Study is currently open with 6 IV patients (Run-In Phase completed and at Dose Level 4) and 3 subQ patients at Dose Level 1 at time of submission. Clinical trial information: NCT04471415.