Primary Myelofibrosis Mortality Risk Halved After Ruxolitinib Approval

The overall risk of death from primary myelofibrosis declined by more than 50% after the U.S. Food and Drug Administration (FDA) approved ruxolitinib for intermediate or high-risk myelofibrosis, according to a retrospective analysis of United States veterans.

Tsewang Tashi, MD, of the Huntsman Cancer Institute at the University of Utah and the George E. Wahlen Department of Veterans Affairs Medical Center, and colleagues conducted the analysis.

They assessed mortality rates in veterans with primary myelofibrosis before and after the FDA approved ruxolitinib, independent of whether they received ruxolitinib. Dr. Tashi and colleagues compared mortality trends from the start of 2007 to the end of 2010, defined as the pre-ruxolitinib approval era, and from the start of 2015 to September 30, 2018, defined as the post-ruxolitinib approval era.

Dr. Tashi and colleagues used primary myelofibrosis diagnosis codes to extract deidentified patient-level data from U.S. Veterans Health Administration (VHA) database. They included patients with at least two primary myelofibrosis claims during the analysis periods who were continuously enrolled in the VHA plan one year prior to and six months after their first primary myelofibrosis diagnosis date. All patients included had at least one available International Prognostic Scoring System (IPSS) risk factor. The researchers did not include patients who had at least one myelofibrosis diagnosis for one year before the index period.

The analysis included 193 veterans with primary myelofibrosis in the pre-ruxolitinib approval cohort, 41.4% of whom had at least two IPSS risk factors; and 974 in the post-ruxolitinib approval cohort, 20.2% of whom had at least two IPSS risk factors. Of the patients in the post-ruxolitinib approval cohort, 8% received ruxolitinib.

While only 8% of the patients in the post-ruxolitinib approval cohort received the drug, the median overall survival time was significantly longer in the post-ruxolitinib approval cohort (not reached; 95% CI, 3.4 years-not reached) than in the pre-ruxolitinib approval cohort (1.7 years; 95% CI, 1.2-2.6; P<.001).

Furthermore, the overall mortality rate was much higher in the pre-ruxolitinib approval cohort (79.8%) than in the post-ruxolitinib approval cohort (47.3%) and the overall risk of death was 53% lower in the post-ruxolitinib approval cohort than in the pre-ruxolitinib approval cohort (hazard ratio, 0.47; 95% CI, 0.37-0.58; P<.001).

“In summary, this retrospective analysis using data from the VHA database showed that patients with [primary myelofibrosis] had a high mortality rate both before and after ruxolitinib approval. A 53% lower risk of mortality was observed for patients diagnosed after ruxolitinib approval, possibly due to overall improvements in diagnosis and management of [primary myelofibrosis],” Dr. Tashi and colleagues concluded. “However, given that only a small portion of patients in the post-ruxolitinib group received ruxolitinib in this study, future analyses should examine mortality differences in patients who received ruxolitinib compared with those who did not, using data from real-world clinical practice.”

Reference

Tashi T, Yu J, Pandya S, Dieyi C, Scherber R, Parasuraman S. Trends in overall mortality among US veterans with primary myelofibrosis. BMC Cancer. 2023;23(1):48.