Enasidenib as maintenance following allogeneic hematopoietic cell transplantation for IDH2-mutated myeloid malignancies

• Published in: Blood advances 2022-11, Vol.6 (22), p.5857-5865
• Main Authors: Fathi, Amir T., Kim, Haesook T., Soiffer, Robert J., Levis, Mark J., Li, Shuli, Kim, Annette S., Mims, Alice S., DeFilipp, Zachariah, El-Jawahri, Areej, McAfee, Steven L., Brunner, Andrew M., Narayan, Rupa, Knight, Laura W., Kelley, Devon, Bottoms, AJ S., Perry, Lindsey H., Wahl, Jonathan L., Brock, Jennifer, Breton, Elayne, Ho, Vincent T., Chen, Yi-Bin
• Format: Article
• Language: English
• Subjects: Regular
• ISSN: 2473-9529; 2473-9537
• DOI: 10.1182/bloodadvances.2022008632

•Enasidenib is well-tolerated as maintenance therapy following hematopoietic cell transplantation for IDH2-mutated myeloid malignancies.•Relapse rate was low with enasidenib maintenance, with a promising 2-year progression-free and overall survival among IDH2-mutated patients. [Display omitted] IDH2 (isocitrate dehydrogenase 2) mutations occur in approximately 15% of patients with acute myeloid leukemia (AML). The IDH2 inhibitor enasidenib was recently approved for IDH2-mutated relapsed or refractory AML. We conducted a multi-center, phase I trial of maintenance enasidenib following allogeneic hematopoietic cell transplantation (HCT) in patients with IDH2-mutated myeloid malignancies. Two dose levels, 50mg and 100mg daily were studied in a 3 × 3 dose-escalation design, with 10 additional patients treated at the recommended phase 2 dose (RP2D). Enasidenib was initiated between days 30 and 90 following HCT and continued for twelve 28-day cycles. Twenty-three patients were enrolled, of whom 19 initiated post-HCT maintenance. Two had myelodysplastic syndrome, and 17 had AML. All but 3 were in first complete remission. No dose limiting toxicities were observed, and the RP2D was established at 100mg daily. Attributable grade ≥3 toxicities were rare, with the most common being cytopenias. Eight patients stopped maintenance before completing 12 cycles, due to adverse events (n=3), pursuing treatment for graft-vs-host disease (GVHD) (n=2), clinician choice (n=1), relapse (n=1), and COVID infection (n=1). No cases of grade ≥3 acute GVHD were seen, and 12-month cumulative incidence of moderate/severe chronic GVHD was 42% (20-63%). Cumulative incidence of relapse was 16% (95% CI: 3.7-36%); 1 subject relapsed while receiving maintenance. Two-year progression-free and overall survival were 69% (95% CI: 39-86%) and 74% (95% CI, 44-90%), respectively. Enasidenib is safe, well-tolerated, with preliminary activity as maintenance therapy following HCT, and merits additional study. The study was registered at www.clinicaltrials.gov (#NCT03515512).