153TiP High-dose rate Interstitial brachytherapy as monotherapy for extremities soft tissue sarcoma: A phase II study

follow up, n6, 46% experienced rash; n6, 46% diarrhea; n3, 23% required phosphate supplement.Delayed AEs included a case of hidradenitis.Among the 4 female pts, 3 (75%) experienced ovarian toxicity.The 3 pts who underwent dose reductions did so due to rash, diarrhea and fatigue; and diarrhea, respectively.All pts tolerated the reduced dose of 100 mg BID.At the most recent follow-up, 8 pts (62%) had reported improved pain from baseline. 2 out of 5 pts (40%) with intrabdominal tumors had RECIST 1.1 partial response.Conclusions: Nirogacestat was well tolerated, with management of AEs at first month associated with dose interruptions but infrequent dose reductions.Our findings support the recommended starting dose of 150 mg twice daily (BID) in real-world experience.