Following Approval of Ruxolitinib, Relative Survival of pMF Has Slightly Increased

The nationwide, population-based study analyzed data on over 1900 patients with primary myelofibrosis (pMF), comparing rates of survival from 2001-2010 with 2011-2018.

Over the last few decades, the relative survival (RS) of primary myelofibrosis (pMF) has increased, according to a new study offering data from a real-world setting on how the arrival of ruxolitinib has affected survival for these patients.

The nationwide, population-based study from the Netherlands analyzed data on more than 1900 patients with pMF, comparing rates of survival from 2001-2010 with 2011-2018.

Between the periods, there was a slight increase in 5-year survival among patients, increasing from 51% to 55%, with the biggest survival increases being seen in patients who were older than 65 years at the time of their diagnosis. Among these patients, 5-year RS increased from 38% to 45%.

“In accordance with previous literature, RS was markedly worse in older patients," the authors wrote.

Higher rates of mortality were also seen in male patients and in patients who had a prior malignancy.

The study included a subgroup of 700 patients with known International Prognostic Scoring System (IPSS) scores and treatments they received. Unsurprisingly, older patients had higher IPSS scores.

"In the subgroup of patients with known IPSS scores (diagnosed between 2014 and 2018), a clear association between RS and the IPSS risk category was found," the authors wrote. "Furthermore, the multivariable analysis indicated higher excess mortality ratios both in males and in patients with a prior malignancy.”

Younger patients (< 65 years) were more likely to receive early allogeneic stem cell transplantation, which increased slightly from 8% to 11% between the 2 periods. Meanwhile, use of other systemic therapy increased across all patients, rising from 3% to 14%, mainly driven by janus kinase (JAK) 1/2 inhibitors like ruxolitinib. Other systemic treatments included immunomodulatory drugs and interferon-alpha.

“The parallel increase in RS and early use of ‘other therapy’ (mainly concerning ruxolitinib) suggests effectiveness of the latter in our real-world population,” wrote the researchers. “Although the increase in the use of other therapy was similar in both age groups, the higher disease severity in patients aged >65 years might explain the greater effect size in this group. This is supported by the final overall survival analysis from the Controlled Myelofibrosis Study with Oral JAK inhibitor Treatment 1 trial.”

Reference

Slot S, Dinmohamed A, Visser O, Boekhorst P, Zweegman S. Survival in primary myelofibrosis: A population-based analysis in the Netherlands. HemaSphere. 2021;5(7):e595.