Sacituzumab govitecan (SG) as second-line (2L) treatment for extensive stage small cell lung cancer (ES-SCLC): Preliminary results from the phase II TROPiCS-03 basket trial

Dowlati, A Cervantes, A Babu, S Hamilton, EP Wong, SF Tazbirkova, A Sullivan, IG van Marcke, Cédric [UCL] Italiano, A Patel, J Mekan, S Wu, T Chiang, AC et al.[show all]

Background Treatment options are limited for patients (pts) with ES-SCLC that progresses after anti-programmed death ligand 1 (PD-L1) therapy and chemotherapy (chemo). SG, a Trop-2-directed antibody-drug conjugate, demonstrated antitumor activity in previously treated ES-SCLC in a phase 1/2 study (Bardia, et al. Ann Oncol. 2021). TROPiCS-03 (NCT03964727) is an open-label, multicohort, phase 2 study evaluating SG in pts with metastatic or locally advanced solid tumors. Here, we report preliminary results from the ES-SCLC cohort. Methods Adult pts with ES-SCLC that progressed after no more than 1 prior line of platinum-based chemo and anti-PD-(L)1 therapy received SG 10 mg/kg on Days 1 and 8 of a 21-day cycle. The primary endpoint was objective response rate (ORR) by investigator assessment (INV) per RECIST v1.1. Key secondary endpoints included clinical benefit rate (CBR), duration of response, progression-free survival, overall survival, and safety. Pts who received ≥1 dose of SG were included in the safety analysis and pts who received ≥1 dose of SG and had ≥13.0 weeks of follow-up were included in the efficacy analysis. Results As of 18 April 2023, 26 pts received ≥1 dose of SG. Median age was 67 years (range, 48-79) and 89% of pts had an ECOG performance status of 1. Median follow-up was 3.5 months (range, 0.6-9.4). Treatment was ongoing for 16 (62%) pts. In the efficacy analysis (n=14), ORR was 29% and CBR was 36% (Table). In the safety analysis (n=26), any-grade treatment-related adverse events (TRAEs) occurred in 96% (grade ≥3, 46%) of pts. No TRAEs leading to discontinuation of study treatment were reported to date. No deaths due to AEs were reported to date. Conclusions SG as 2L treatment for ES-SCLC demonstrated promising antitumor activity and manageable safety, with no TRAEs leading to discontinuation reported to date. Additional data with more pts and longer follow-up will be presented.