According to Harinder Gill, MD, MBBS, FRCP, FRCPath, there is no optimal treatment strategy established for patients with early or prefibrotic primary myelofibrosis (pre-PMF) and Dynamic International Prognostic Scoring System (DIPSS) low or intermediate-1 risk myelofibrosis (MF)—a population that largely progresses to overt primary or higher-risk disease.
Dr. Gill and colleagues evaluated ropeginterferon alfa-2b (P1101), a next-generation monopegylated interferon alfa-2b for myeloproliferative neoplasms (MPN), in patients with pre-PMF and DIPSS low or intermediate-1 status. They reported that P1101 was well-tolerated and effectively reduced cytokines and induced molecular response. Their results were presented at the 64th ASH Annual Meeting and Exposition.
P1101 Shows Promising Efficacy for Vulnerable Pre-PMF Patients
The multicenter phase 2 study included 56 patients (male, 33; median years of age, 58 [range, 30-87 years]), of which 38 had morphologically confirmed pre-PMF, 5 had overt PMF, 3 had postpolycythemia vera MF, and 10 had postessential thrombocythemia MF. In 53 patients with available next-generation sequencing, 39 (74%) patients had JAK2 V617F, 13 (25%) had CALR, and 1 (2%) had MPL mutations.
At the data cutoff of July 28, 2022, the median follow-up duration was 24 weeks (range, 2-28 weeks). The clinicohematologic complete response rate was 74% at week 12 (n=46) and 67% at week 24 (n=30). Notably, 36 (92%) of 39 patients with JAK2 V617F mutation had stable or improved allele burden, with 3 (8%) achieving a >50% reduction in allele burden. One of those 3 patients had undetectable allele from week 16 onward.
The most common adverse events were malaise, anemia, muscle pain, and hair loss, and the authors wrote there were no treatment discontinuations, new safety signals, or treatment-related deaths.
In closing, Dr. Gill noted the study is still recruiting and supported the potential efficacy of P1101 in the vulnerable population of patients with pre-PMF.
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