At a median daily dose of ruxolitinib 20 mg and a median 25.1 weeks of drug exposure, 37.9% of patients required dose adjustment/interruption, and 8.7% of patients discontinued ruxolitinib. Anemia, thrombosis, and thrombocytopenia were the most common hematologic adverse events, most of which were classified as grade 1 or 2. Regarding nonhematologic adverse effects, headache (24.5%) and diarrhea (14.5%) were most common, but only 1 of these events was classified as grade 3 or higher.

At 24 weeks, control of hematocrit level was achieved by 45.3% of patients, and 37.3% of evaluable patients had experienced at least a 50% reduction in disease-related symptoms as measured by the Myeloproliferative Neoplasm-Symptom Assessment Form Total Symptom Score (MPN-SAF TSS).

Based on these results, the researchers concluded that “the overall efficacy results from this study were similar to the reported values in the pivotal RESPONSE studies.” In addition, the safety profile was consistent with the known profile of ruxolitinib. These results further validate the use of ruxolitinib for patients with hydroxyurea intolerant/resistant polycythemia vera.


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1. Foltz L, Pica GM, Zerazhi H, et al. Safety and efficacy findings from the open-label, multicenter, phase 3b, expanded treatment protocol study of ruxolitinib for treatment of patients with polycythemia vera who are resistant/intolerant to hydroxyurea and for whom no alternative treatments are available [published online July 30, 2019]. Leuk Lymphoma. doi: 10.1080/10428194.2019.1636985

2. Jakafi® [package insert]. Wilmington, DE: Incyte Corp; 2019. 3. Vannucchi AM, Kiladjian JJ, Griesshammer M, et al. Ruxolitinib versus standard therapy for the treatment of polycythemia vera. N Engl J Med. 2015;372:426–435.