Prognostic value of blasts in peripheral blood in myelofibrosis in the ruxolitinib era

• Published in: Cancer Vol. 126; no. 19; pp. 4322 - 4331
• Main Authors: Masarova, Lucia, Bose, Prithviraj, Pemmaraju, Naveen, Daver, Naval G., Zhou, Lingsha, Pierce, Sherry, Sasaki, Koji, Kantarjian, Hagop M., Estrov, Zeev, Verstovsek, Srdan
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.10.2020
• Subjects: blasts; Blood circulation; Bone marrow; Janus kinase; Janus kinase 2; Medical prognosis; Multivariate analysis; Myelofibrosis; Oncology; outcome; Patients; Peripheral blood; ruxolitinib; Survival; blasts; myelofibrosis; ruxolitinib; outcome
• ISSN: 0008-543X; 1097-0142
• DOI: 10.1002/cncr.33094

Background Circulating blasts (peripheral blood [PB] blasts) ≥1% have long been considered an unfavorable feature for patients with primary myelofibrosis. Whether further quantification of PB blasts and their correlation with bone marrow (BM) blasts have incremental value with regard to patient prognostication is unclear. Similarly, the role of the JAK1/JAK2 inhibitor ruxolitinib (RUX) is not well defined in patients who have increased blasts. Methods The authors retrospectively studied 1316 patients with myelofibrosis who presented at their institution between 1984 and 2018 and had available PB and BM blasts. Results The PB blast percentage influenced overall survival (OS) only among patients who had BM blasts <5%, with a median OS of 64 months for patients with 0% PB blasts, 48 months for those with 1% to 3% PB blasts, and 22 months for those with 4% PB blasts (P < .01). Patients who had 4% PB blasts and 5% to 9% BM/PB blasts had clinical features similar to those of patients who had 10% to 19% blasts. Although the OS of the former patients was longer than in patients who had 10% to 19% blasts, it was not statistically different (median OS: 22, 26, and 13 months, respectively; P > .05). Forty‐four percent of patients received RUX throughout their disease course. All patients who had <10% blasts (PB or BM) and received treatment with RUX had superior OS compared with those who did not receive RUX within the same group. PB blasts ≥4% and BM blasts ≥5% were significant for predicting inferior survival in multivariate analysis. Conclusions The current results provide comprehensive insight into the role of peripheral blasts in patients with myelofibrosis and indicates that patients who have PB blasts ≥4% have an unfavorable prognosis. RUX provides a survival benefit to patients who have PB blasts <10%. Patients who have myelofibrosis with ≥4% peripheral blood blasts and/or ≥5% bone marrow blasts have inferior outcomes compared with those who have lower blast percentages. Ruxolitinib provides a survival benefit for all patients who have <10% peripheral blood or bone marrow blasts.