ATLANTA – Shares of Blueprint Medicines Corp. (NASDAQ:BPMC) popped 25 percent at Monday's opening bell, closing the day at $88.32 for a gain of $16.46, after the company wowed participants at the American Society of Hematology (ASH) annual meeting with a presentation of data from the ongoing phase I trial of BLU-285 – now named avapritinib – in advanced systemic mastocytosis (SM). Findings from the dose-escalation portion of the phase I study showed an overall response rate (ORR) of 72 percent and a disease control rate (DCR) of 100 percent in patients evaluable for response as of Oct. 4, based on the International Working Group-Myeloproliferative Neoplasms Research and Treatment and European Competence Network on Mastocytosis (IWG-MRT-ECNM) consensus criteria. At data cut-off, avapritinib was well tolerated and most adverse events (AEs) reported by investigators were grade 1 or 2. No discontinuations occurred due to treatment-related AEs, and 30 of 32 patients remained on therapy with a median treatment duration of nine months.