On October 18, 2022 Salarius Pharmaceuticals, a clinical-stage biopharmaceutical company using protein inhibition and protein degradation to develop cancer therapies for patients in need of new treatment options, reported that, as per protocol design, it is voluntarily pausing new patient enrollment in the company’s Phase 1/2 trial of seclidemstat as a treatment for Ewing sarcoma and FET-rearranged sarcomas (Press release, Salarius Pharmaceuticals, OCT 18, 2022, View Source [SID1234622124]).
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The pause in new patient enrollment is due to a metastatic FET-rearranged sarcoma patient death that was classified as a suspected unexpected serious adverse reaction (SUSAR). Upon review of the SUSAR and available information by the company’s independent Safety Review Committee for the clinical trial, patients currently receiving seclidemstat treatment may continue treatment after consulting with their physician.
Salarius communicated the details of the SUSAR to the U.S. Food and Drug Administration (FDA) and intends to further analyze the available data with the goal of understanding how best to proceed and restart enrollment as soon as possible. Salarius continues to plan to release interim sarcoma clinical trial results later this year.
"Patient safety is our primary concern, and this is reflected in the design of our clinical trial protocol, which automatically paused enrollment based upon this SUSAR," said David Arthur, chief executive officer of Salarius. "Unfortunately, pauses to enrollment occur in early-stage drug development, but these pauses allow time to understand new data and adjust clinical protocols and development plans as needed. We plan to restart enrollment as soon as possible."
About the Phase 1/2 Ewing sarcoma and other FET-rearranged sarcomas trial
The Phase 1/2 trial currently is in its dose-expansion stage, which includes three patient arms. The first patient arm is enrolling up to 30 patients with Ewing sarcoma, a rare and deadly pediatric bone cancer, and will investigate seclidemstat in combination with topotecan and cyclophosphamide, a commonly used second- and third-line chemotherapy regimen. Salarius believes data released during ASCO (Free ASCO Whitepaper) 2021 demonstrated synergy in a Ewing sarcoma cell line when seclidemstat was used in combination with these agents. Salarius also believes this treatment combination and its use as a second- and third-line therapy could greatly expand the addressable patient population for seclidemstat and improve outcomes by allowing physicians to introduce seclidemstat earlier in the Ewing sarcoma continuum of care.
The trial’s second patient arm is investigating seclidemstat as a single agent in up to 15 patients with myxoid liposarcoma. The third patient arm is investigating seclidemstat as a single agent in up to 15 patients with select sarcomas that share a similar biology to Ewing sarcoma, also referred to as FET-rearranged or Ewing-related sarcomas. In data released at ASCO (Free ASCO Whitepaper) 2021, a subset of patients with advanced FET-rearranged sarcomas treated with single-agent seclidemstat resulted in stable disease and prolonged time to progression, which Salarius believes suggests disease control, a clinically relevant endpoint for soft tissue sarcomas.
All three patient arms are designed to evaluate safety and efficacy in patients with advanced disease. Per protocol design, new patient enrollment will be stopped, or paused, when 1) any death or life-threatening adverse experience deemed possibly or definitely related to the investigational product is observed, or 2) it is determined that the protocol precipitates multiple patient non-compliance beyond reasonably missed visits.