HOUSTON — Myelofibrosis Is a rare disorder in which abnormal blood cells and fibers build up in the bone marrow. It is classified as a myeloproliferative neoplasm (MPNs) in which bone marrow cells that produce blood cells develop and function abnormally.

Intermediate/high risk primary myelofibrosis has various outcomes and differential effects on overall survival (OS) based on risk, according to a new study. The research on overall survival of veterans with MF was presented recently in conjunction with the 2020 American Society of Clinical Oncologists Annual Meeting.1

Baylor College of Medicine-led researchers pointed out that data on the OS of VHA patients  with MF are limited but present an opportunity because of the health system documented follow up in patients with multiple comorbid conditions.

The study team noted that, in phase 3 trials, ruxolitinib, a JAK1/JAK2 inhibitor, was shown to improve OS in MF patients, leading to Food and Drug Administration approval in 2011. In the study, the investigators looked at mortality trends among U.S. veterans with primary myelofibrosis before and after approval of ruxolitinib.

The study used de-identified PMF patient-level data obtained from VISNs, with a focus on PMF diagnosis codes (ICD-9: 238.76, ICD-10: D47.1). The information was collected from two VHA data periods – Jan. 1, 2006, to Dec. 31, 2010, and Jan. 1, 2014 to Dec. 31, 2020 – which reflected years pre- and post-ruxolitinib approval.

Patients in the trial were required to be continuously enrolled in VHA care from one calendar year prior to six months after the index date. Included were participants who had int/high-risk PMF defined as more than one risk factor at diagnosis, i.e,, age greater than 65, hemoglobin [Hb] of less than 10 g/dL, white blood cells [WBCs] greater than 25 × 109/L. Researchers also recorded demographic and clinical characteristics and estimated all-cause one-year, two-year and overall mortality rates and time to death from index until end of data availability were estimated using Kaplan-Meier (KM) methodology; univariate Cox regression was used to examine the hazard ratio (HR) for all-cause mortality for the pre- and post-RUX cohorts.

Ultimately, the study included 244 patients pre-ruxolitinib and 1,005 post-ruxolitinib. Most patients were 65 or older (84% vs 95%), male (99% vs 99%), and white (64% vs 77%). Patients — 64% vs 32% — had Hemoglobin less than 10 g/dL at PMF diagnosis and 20% vs. 14% had WBCs > 25 × 109/L for pre- and post-RUX cohorts, respectively.

Results indicated that the one-year, two-year and overall mortality rates for pre- vs. post-ruxolitinib were 45%, 63%, and 89% vs. 27%, 37%, and 57%, respectively. Time from index PMF diagnosis to death was significantly longer for the post- vs. pre- ruxolitinib cohort (median [95% CI], 1091 [989‒NR] vs. 430 [347‒568] d; P< 0.001), and risk of death was 47% lower in the post- vs pre- ruxolitinib period (HR, 0.53; P< 0.001), the researchers reported.

“In this retrospective analysis, patients with PMF had a high mortality rate; a 47% lower risk of mortality was observed post-RUX approval,” the authors concluded. “Multiple factors may have influenced the lower mortality observed, which will be further explored.”

  1. Rivero G, Yu J, Pandya S, Dievi C, Parasuraman D. Trends in overall mortality among US veterans with intermediate (Int) / high-risk primary myelofibrosis (PMF). Abstract abstr e19534). 2020 ASCO Annual Meeting. May 29-31, 2020. https://meetinglibrary.asco.org/record/185333/abstract