SARC037: Phase II results of trabectedin given as a 1-hour (h) infusion in combination with low dose irinotecan in patients (pts) with relapsed/refractory Ewing sarcoma (ES).
Patrick J. Grohar, Karla V. Ballman, Rachel S. Heise, Leo Mascarenhas, John Glod, Mary Frances Frances Wedekind, Jenna M. Gedminas, Steven G. DuBois, Robert G. Maki, Brian D. Crompton, William D. Figg, Rochelle Bagatell, Theodore W. Laetsch, Mark S. Diamond, Fariba Navid, Ryan D. Roberts, Brigitte C. Widemann, Denise K. Reinke, Rashmi Chugh
Abstract
11508 Background: Trabectedin(T) is a marine-derived minor groove DNA binding compound that alters transcription factor activity. Preclinical data suggests that T suppresses the oncogenic driver of ES, EWS::FLI1. This suppression requires a threshold concentration of T and is potentiated by low doses of Irinotecan(I). Preliminary clinical activity and reversal of the EWS::FLI1 transcriptome was seen in patients (pts) in the phase I portion of SARC037. Here we report the phase II results of T with I at the recommended dose in pts with relapsed/refractory ES. Methods: In this open-label multicenter study, T was given at 1 mg/m 2 as a 1-h infusion on day(D)1 with I at 25 mg/m 2 intravenously on D2 and D4 of a 21D cycle. Key eligibility criteria were EWS::FLI1 fusion transcript, age ≥6 years, ECOG ≤2, adequate organ function, and willing to have a research biopsy if safely accessible. The primary objective was to determine the objective response rate (ORR) assessed by RECIST v1.1. Secondary objectives were progression-free survival (PFS), duration of response (DOR), and safety. This study used a Simon two-stage design that required 4 or more responses (CR or PR) at the final analysis to establish treatment activity. Results: 18 pts enrolled from 12/2022-12/2023 across 6 sites, 8F/10M, median age 21y (9-43). Pts had a median of 3 (1-7) prior therapy lines, including I in 67% of pts. Of 16 pts evaluable for response at the cutoff date, 5 pts had a PR, and 2 pts had SD. Two pts have evaluations pending and two pts were removed for toxicity before the first evaluation. Median time to response was 2.6 months(m), 6-month PFS was 37.7% (95% CI 18.3%, 77.7%), and all responses were sustained at the time of data cutoff at 10.4+, 7.5+, 5.5+, 5.0+ and 4.6+ m. There were no G5 AEs. Most pts had molecular profiling, translocation testing, as well as ctDNA collection, quantitation, and analysis. A subset of pts had pre- and post-treatment biopsies for RNA sequencing and evaluation of the impact of drug exposure on the EWS::FLI1 transcriptome. Conclusions: T+I exhibited anti-tumor activity in heavily pretreated pts with ES and met its prespecified ORR with 5 PRs in 16 evaluable patients, all of which are ongoing at data cutoff. There were no unexpected safety signals. The combination of T given as a 1h infusion and low-dose I demonstrated meaningful clinical benefit and is worthy of further study in ES pts. Analysis of biological correlates is ongoing. Clinical trial information: NCT04067115 .