Characteristics of patients with myelofibrosis on ruxolitinib for three or more years

• Published in: Journal of clinical oncology Vol. 40; no. 16_suppl; p. e19082
• Main Authors: Masarova, Lucia, Bose, Prithviraj, Pemmaraju, Naveen, Chifotides, Helen T., Zhou, Lingsha, Estrov, Zeev, Kantarjian, Hagop M., Verstovsek, Srdan
• Format: Journal Article
• Language: English
• Published: 01.06.2022
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/JCO.2022.40.16_suppl.e19082

e19082 Background: Ruxolitinib (RUX) was the first JAK1/2 inhibitor approved for patients with advanced phase of myelofibrosis (MF) with median therapy duration of about 3 years. We aimed to characterize clinical features of patients treated with RUX for ≥3 years who presented to our institution between January 2000 and January 2019. Methods: Retrospective review of medical records of 131 patients who received RUX for ≥3 years. Clinical characteristics, therapy details and overall survival (OS; Kaplan Meier method) were assessed at/from the time of RUX initiation. Cox proportional hazard model was used for univariate (known clinical variables) and multivariate analysis (p < 0.05 on previous analysis) of factors associated with OS. Results: Median age of patients was 67 years (range, 31-84), 56% were males (clinical characteristics in Table). Among 62 patients with ≥ 28 gene next generation sequencing; 19, 24 and 19 patients had none, 1 and ≥2 mutations beyond JAK2, MPL, CALR, respectively. Eighty four percent of patients received RUX as frontline therapy. Median time to RUX from presentation and from MF was 4 (range, 0.1-123) and 11 months (range, 0.1-228), respectively. Starting dose of RUX was ≥ 15 mg, 10 mg and 5 mg twice daily in 110 (84%), 17 (13%), and 4 (3%) patients, respectively. Median duration of RUX therapy was 76 months (95% CI, 56-88). At the time of last follow-up (median duration of 104 months; 95% CI, 93-115), 44 patients (35%) were on RUX. Reasons for discontinuation in the remaining patients included MF progression (n = 54; 62%), blastic phase (n = 7; 8%), cytopenias (n = 4; 5%) and unrelated causes (n = 22, 25%). Median OS since therapy start was 90 months (95% CI, 76-104) with 40% of patients being alive at 10 years. Patients ≥ 65 years had median OS of 76 months (95% CI, 67-85). Patients with intermediate 2 (n = 81) or high risk (n = 29) DIPSS at RUX start had median OS of 89 (95% CI, 71-107) and 72 (95% CI, 55-89) months, respectively. Factors affecting OS on univariate analysis (HR, 95% CI, p-value) were age > 65 years (2.56, 1.49-4.35, < 0.001), neutrophils % (0.97, 0.95-0.99, 0.006), blasts % (1.213, 1.035-1.421, 0.017), performance status of <2 (0.228, 0.069-0.752, 0.015). The only factors retaining significance on multivariate analysis were age > 65 years (2.7, 1.50-4.14, < 0.001) and neutrophils % (0.66, 0.29- 0.86, 0.012). Conclusions: Forty percent of patients who remained on RUX for ≥3 years were alive at 10 years since their therapy initiation. Age remains the major predictive factor of survival despite long RUX therapy.[Table: see text]