Inhibrx reports preliminary Phase 1 efficacy and safety data in Ewing sarcoma

Inhibrx announced preliminary efficacy and safety data from the Phase 1 trial of INBRX-109 in combination with Irinotecan and Temozolomide for the treatment of advanced or metastatic, unresectable Ewing sarcoma. Inhibrx presented this dataset as of the data cut of September 8th, 2023 at the Annual Connective Tissue Oncology Society Conference. Among the 13 patients evaluable, which included 7 classical Ewing sarcoma patients and 6 round cell sarcoma patients, the observed disease control rate was 76.9%, or 10 out of 13 patients. There were 7 patients who achieved partial responses – 53.8% -, 5 of which were observed in classical EWS patients – 71.4% – and 2 of which were observed in RCS patients – 33.3% -. Durable clinical benefit was observed in 4 patients who achieved disease control lasting greater than 6 months. Overall, INBRX-109 in combination with IRI/TMZ was well tolerated. The most common adverse events were diarrhea, nausea and fatigue, all consistent with the known safety profile of IRI/TMZ. No grade 3 or higher liver-related events occurred.