Momelotinib, an oral Janus kinase (JAK) inhibitor, is non-inferior to ruxolitinib in reducing spleen volume, though not for improving disease-related symptoms, among patients with myelofibrosis not previously treated with a JAK inhibitor, according to a presentation at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.1

Presenter Ruben A. Mesa, MD, from the Mayo Clinic in Scottsdale, Arizona, indicated that more than 50% of patients show mutations in JAK2 V617F.

For the phase 3 Simplify 1 study (ClinicalTrials.gov Identifier: NCT01969838), patients were randomly assigned to receive momelotinib (215 patients) or ruxolitinib (217 patients) for 24 weeks.

The primary endpoint was splenic response rate (SRR; at least 35% reduction in volume from baseline) at 24 weeks.

At 24 weeks, 81% and 93% of patients in the momelotinib and ruxolitinib arms, respectively, completed 24-week therapy.

After 24 weeks, momelotinib was deemed non-inferior to ruxolitinib: SRRs were 26.5% for momelotinib and 29.0% for ruxolitinib (P = .011).

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For patient-reported Total Symptom Score (TSS), response rate for momelotinib was inferior to ruxolitinib: 28.4% vs 42.2% for ruxolitinib (P = .98).

The most common grade 3 or worse events among patients on momelotinib were thrombocytopenia (7%) and anemia (6%). Grade 3 or worse adverse events among patients on ruxolitinib included anemia (23%), thrombocytopenia (5%), and neutropenia (5%).

Adverse events leading to treatment discontinuation occurred in 13% of patients on momelotinib and 6% of patients on ruxolitinib.

“Momelotinib was non-inferior to ruxolitinib for the primary endpoint of splenic response rate, but failed to meet the non-inferiority criterion for the key secondary endpoint of symptom response,” Dr Mesa said.

Reference

  1. Mesa RA, Kiladjian JJ, Catalano JV, et al. Phase 3 trial of momelotinib (MMB) vs ruxolitinib (RUX) in JAK inhibitor (JAKi) naïve patients with myelofibrosis (MF). J Clin Oncol. 2017;35(suppl; abstr 7000).

This article originally appeared on Cancer Therapy Advisor