Can Splenic Irradiation Improve HSCT for Myelofibrosis?

Splenic irradiation was a viable strategy to reduce spleen size prior to hematopoietic stem cell transplantation (HSCT) in patients with myelofibrosis who failed on treatment with Janus kinase (JAK) inhibitors, according to a study published in the American Journal of Hematology.

“Irradiation was associated with significantly reduced relapse after [HSCT],” stated the authors, led by Nico Gagelmann, MD, of the University Medical Center Hamburg-Eppendorf in Germany.

“In terms of safety, while cytopenias were frequent after irradiation, there was no direct correlation between total irradiation dose and safety as well as efficacy, thus suggesting that high doses could be avoided,” Dr. Gagelmann and colleagues wrote.

HSCT for Myelofibrosis Improved with Splenic Radiation

The study included 59 patients who received splenic irradiation within a median of two weeks (range, 0.9-12) prior to HSCT. The median spleen size prior to irradiation was 23 cm (range, 14-35). Overall, 97% (n=57) of patients had significant and rapid reductions in spleen size after irradiation, with a median decrease of 5.0 cm (95% CI, 4.1-6.3).

The rate of three-year overall survival was 62% (95% CI, 48-76) and one-year nonrelapse mortality was 26% (95% CI, 14-38). Independent predictive factors for survival included severe thrombocytopenia and anemia prior to irradiation, transplant-specific risk score, higher-intensity conditioning, and portal vein thrombosis.

In a propensity score-matched comparison, the three-year incidence of relapse was 12% with splenic irradiation (P=.01) versus 28% for immediate HSCT and 38% with splenectomy.

Thrombocytopenia occurred the most of any adverse event, though authors noted there was no correlation between irradiation dose and hematological toxicities.

“In conclusion, this first collaborative study on splenic irradiation followed by HSCT myelofibrosis suggests splenic irradiation as a reasonable approach in patients with splenomegaly and JAK inhibition failure,” the report closed.

Related: Gabriela Hobbs, MD, Discusses Updated Data on Ruxolitinib Use During, After Transplant

Reference

Gagelmann N, Hobbs GS, Campodonico E, et al. Splenic irradiation for myelofibrosis prior to hematopoietic cell transplantation: a global collaborative analysis. Am J Hematol. 2024. doi:10.1002/ajh.27252