OBI-3424, a novel AKR1c3-activated prodrug, exhibits potent efficacy against preclinical models of T-ALL

Purpose: OBI-3424 is a highly selective prodrug that is OBI-3424 significantly prolonged the event-free survival (EFS) converted by aldo-keto reductase family 1 member C3 of nine of nine ALL PDXs by 17.1–77.8 days (treated/control (AKR1C3) to a potent DNA-alkylating agent. OBI-3424 has values 2.5–14.0), and disease regression was observed in eight entered clinical testing for hepatocellular carcinoma and cas-of nine PDXs. A significant reduction (P < 0.0001) in bone trate-resistant prostate cancer, and it represents a potentially marrow infiltration at day 28 was observed in four of six novel treatment for acute lymphoblastic leukemia (ALL). evaluable T-ALL PDXs. The importance of AKR1C3 in the Experimental Design: We assessed AKR1C3 expression by in vivo response to OBI-3424 was verified using a B-ALL PDX RNA-Seq and immunoblotting, and evaluated the in vitro that had been lentivirally transduced to stably overexpress cytotoxicity of OBI-3424. We investigated the pharmacokinet-AKR1C3. OBI-3424 combined with nelarabine resulted in ics of OBI-3424 in mice and nonhuman primates, and assessed prolongation of mouse EFS compared with each single agent the in vivo efficacy of OBI-3424 against a large panel of patient-alone in two T-ALL PDXs. derived xenografts (PDX). Conclusions: OBI-3424 exerted profound in vivo efficacy Results: AKR1C3 mRNA expression was significantly higher against T-ALL PDXs derived predominantly from aggressive in primary T-lineage ALL (T-ALL; n ¼ 264) than B-lineage and fatal disease, and therefore may represent a novel treat-ALL (B-ALL; n ¼ 1,740; P < 0.0001), and OBI-3424 exerted ment for aggressive and chemoresistant T-ALL in an AKR1C3 potent cytotoxicity against T-ALL cell lines and PDXs. In vivo, biomarker-driven clinical trial.