Ivosidenib in Mutant IDH1 Relapsed/ Refractory Myelodysplastic Syndrome: Updated Substudy Results

By: Dr. Kanak Parmar

On October 24, 2023 the U.S. Food and Drug Administration approved ivosidenib for adult patients with relapsed or refractory myelodysplastic syndromes (R/R MDS) with a susceptible isocitrate dehydrogenase-1 (IDH1) mutation.

Study ID number: NCT02074839

Approval was based on the AG120-C-001 a phase 1, open-label, single-arm, multicenter trial of 18 adult patients with relapsed or refractory MDS with an IDH1 mutation. Patients were Ivosidenib was administered orally at a starting dose of 500 mg daily continuous for 28-day cycles until disease progression, unacceptable toxicity, or hematopoietic stem cell transplantation.

Efficacy was established by the rate of complete remission (CR) or partial remission (PR), CR+PR durations, and conversion rate from transfusion dependence to independence. ORR was 83.3% (95% CI 58.6-96.4). CR was 38.9%(95% CI 17.3-64.3) and marrow CR was 44.4% (95% CI 21.5-69.2). The median time-to-CR was 1.9 months.  During the post baseline period out of the 9 transfusion dependent patients  6 became RBC and platelet transfusion independent and out of the rest 9 transfusion independent patients 7 remained transfusion independent. Stem cell transplant was done in 2 patients (11.1%) and 2 patients (11.1%) had progressed to acute myeloid leukemia.

The most common adverse reactions reported in ≥ 20% of patients were diarrhea, nausea, fatigue, neutropenia, anemia, constipation, decreased appetite, white blood cell count decreased, musculoskeletal pain, rash, cough, vomiting and dyspnea.Ivosidenib showed transfusion independence and durable remissions in a substantial proportion of patients with IDH1 R/R MDS.