By Patrick Daly
December 6, 2023
Patients with polycythemia vera (PV) who received ruxolitinib treatment achieved sustained hematocrit control over 80 weeks and had improved symptom control at week 16 compared with patients who received best available therapy (BAT), based on a post hoc pooled analysis of data from the RESPONSE and RESPONSE 2 trials.
The efficacy data were presented at the 65th American Society of Hematology Annual Meeting & Exposition in San Diego, California, by lead author, Claire Harrison, MD, of the Guy’s and St. Thomas’ NHS Foundation Trust in London, United Kingdom.
“Reductions in JAK2V617F allele burden were consistently observed through Week 208 in patients treated with ruxolitinib, including those who crossed over from BAT,” Dr. Harrison and colleagues reported.
The analysis assessed 371 pooled patients from RESPONSE and RESPONSE 2, of which 184 were treated with ruxolitinib and 187 with BAT. The cohort had a median age of 61.8 ± 11 years and most patients were White (88.1%) and male (62.5%). Hematocrit control was defined as hematocrit maintained below 45% starting week 16 plus one or less phlebotomy between baseline and week four.
At week 28, the proportion of patients with hematocrit control was 62.0% (95% CI, 54.5-69.0) in the ruxolitinib group versus 18.2% (95% CI, 12.9-24.5) in the BAT group. Further, 47.3% (95% CI, 39.9-54.8) of patients in the ruxolitinib group had sustained hematocrit control through week 80; authors noted nearly all patients in the BAT group had crossed over to the ruxolitinib group by that point.
The proportion of patients who achieved a 50% or greater reduction from baseline in Myeloproliferative Neoplasms Symptoms Assessment Form Total Symptom Score at week 16 was 48.7% (95% CI, 40.7-56.8) in the ruxolitinib group compared with 18.0% (95% CI, 12.5-24.6) in the BAT group (odds ratio, 4.3; 95% CI, 2.6-7.2), and the mean change in score was -4.4 ± 10.0 and 0.6 ± 6.9, respectively.
Additionally, patients randomized to ruxolitinib had consistently decreased JAK2V617F allele burden through week 208, and mean JAK2V617F allele burden decreased from 66.1% to 41.4% at four years.
“Taken together, these results provide further evidence of the patient benefit of ruxolitinib in patients with PV with or without splenomegaly,” Dr. Harrison and colleagues concluded.
Reference
Harrison C, Kiladjian JJ, Palandri F, et al. Ruxolitinib treatment in polycythemia vera results in reduction in JAK2 allele burden in addition to improvement in hematocrit control and symptom burden. Abstract #4553. Presented at the 65th ASH Annual Meeting & Exposition; December 9-12, 2023; San Diego, California.