Chronic leukemias: ruxolitinib response most likely in those with CNL and CSF3R-mutated disease

  • Dao KT & al.
  • J Clin Oncol
  • 27 Dec 2019

  • curated by David Reilly
  • Univadis Clinical Summaries
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Takeaway

  • Approximately one-third of patients with chronic neutrophilic leukemia (CNL) or atypical chronic myeloid leukemia (aCML) responded to ruxolitinib.
  • Patients with CNL or with CSF3R-mutated disease had a greater likelihood of response.

Why this matters

  • No standard of care currently exists in this setting.

Study design

  • Phase 2 study to investigate ruxolitinib in 44 patients (21 with CNL; 23 with aCML).
  • Median patient age: 72.9 (range, 43.1-92.3) years.
  • 50% of patients had colony-stimulating factor-3 receptor (CSF3R)-mutated disease.
  • The study used Simon’s 2-stage "minimax" design to minimize sample size in the event that the study regimen demonstrated low activity.
  • Funding: Incyte Corporation.

Key results

  • 32.0% overall hematologic response rate (ORR) at the end of 6 cycles in the first 25 patients enrolled.
  • ORR in the overall cohort of 44 patients:
    • 34.9% for all patients.
    • 65.0% in patients with CNL.
    • 8.7% in patients with aCML.
  • Factors associated with increased likelihood of response:
    • CNL diagnosis: OR, 19.5 (P<.001>
    • CSF3R-mutated disease: OR, 13.722 (P=.002).
  • 55% experienced 1 or more grade ≥3 nonhematologic adverse event (AE), but most cases were not treatment-related.  
  • Most common hematologic grade ≥3 AEs included anemia (34.1%) and thrombocytopenia (13.6%).

Limitations

  • Open-label, single-group study.