Abstract
A phase I study demonstrated that ivosidenib, a mutant isocitrate dehydrogenase 1 (mIDH1) inhibitor, showed manageable toxicity and durable disease control in patients with mIDH1 conventional chondrosarcoma (CS). In this study, we present long-term follow-up data on the safety and clinical activity of ivosidenib in patients with mIDH1 conventional CS from this phase I study.
This phase I, open-label, dose-escalation, and expansion study assessed ivosidenib monotherapy in patients with advanced mIDH1 solid tumors, including CS. An ivosidenib dose of 500 mg/day was identified in the dose-escalation phase and used for the expansion phase. The primary outcome was safety and tolerability. Secondary outcomes included objective response rate and progression-free survival. The database lock date for this analysis was March 18, 2024.
Of 168 patients with advanced mIDH1 solid tumors receiving ivosidenib in this study, 21 patients had CS, of which 13 had conventional histology. Six (46.2%), 4 (30.8%), and 3 (23.1%) patients with conventional CS continued ivosidenib treatment for >1 year, >6 years, and >7 years, respectively. Of the 21 patients with CS, 71.4% and 28.6% had treatment-related and serious adverse events, respectively, but no serious adverse events were considered related to ivosidenib. The objective response rate for patients with conventional CS was 23.1%, and the median duration of response was 53.5 months. The median progression-free survival of patients with conventional CS treated with ivosidenib was 7.4 months.
Ivosidenib demonstrated long-term disease control and manageable toxicity for some patients with mIDH1 conventional CS and is under further investigation (NCT06127407).
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