EP0057 in Combination With Olaparib in Relapsed Advanced Gastric Cancer and Small Cell Lung Cancer

The aim of EP0057 - 202 is to assess the safety and efficacy of EP0057 in combination with Olaparib (a PARP inhibitor) in two cancers where there is a high unmet need: extensive stage small cell lung cancer (SCLC) and ATM-negative gastric cancer (GC). EP0057-202 is a non-comparative, multi-arm, multi-centre, open label, Phase 2 study to determine the efficacy, safety, and tolerability of EP0057 in combination with olaparib (an approved PARP inhibitor) in defined patient populations with relapsed\* GC and SCLC. \*(see Eligibility Criteria for definition of "relapse" for each tumour type/population) The treatment cohorts will open sequentially at the Sponsor's discretion and patients may be enrolled into each cohort concurrently. EP0057 is an investigational nanoparticle-drug conjugate administered intravenously. The rationale for developing EP0057 is to enable selective entry of EP0057 into tumour tissue and as a result create preferential accumulation of EP0057, and therefore of the payload Camptothecin, to translate into maximum tumour cell killing.

EP0057 - 202 is a Phase 2 multi arm, open label study in defined populations of patients with SCLC and GC. The Primary objectives of Arm 1 will be to investigate the efficacy, as defined by best Objective Response Rate (ORR) of EP0057 in combination with Olaparib in patients with ataxia-telangiectasia mutated protein (ATM)-negative relapsed, advanced GC. The Primary objectives of Arm 2 will be to investigate the efficacy, as defined by the best ORR of EP0057 in combination with Olaparib in patients with relapsed extensive stage SCLC. The secondary objectives of both arms will be to further investigate the efficacy of EP0057 in combination with olaparib in the target patient population of each arm by assessment of the following: * Progression-free survival (PFS) * Overall survival (OS) * Duration of overall response (DoR) * Disease control rate (DCR) Secondary objectives of arms 1 and 2 also include exploring the safety and tolerability of EP0057 when combined with olaparib in patients with GC and SCLC. Exploratory objectives may or may not be performed during the course of the study, but if so, where available at the time of publication, results from these analyses will be reported in the clinical study report (CSR). Exploratory objectives are to: * Examine the PK characteristics of EP0057 in combination with olaparib * Investigate the impact of HRD (homologous recombination deficiency) status on primary and secondary endpoints, as analysed by sub-groups of HRD status. It is estimated that approximately 115 patients will be enrolled into the study. The study will aim to recruit 34 patients across both arms of the study in stage 1. The study will then aim to recruit an additional 81 patients across both arms in the second stage.