What Is the Role of Splenic Irradiation Before HSCT in Patients With MF?

Splenic irradiation before allogeneic hematopoietic stem cell transplantation (HSCT) is associated with reduced spleen size and lower incidence of relapse in patients with myelofibrosis (MF), according to a recent study.

The retrospective study was led by Nico Gagelmann, MD, of the University Medical Center Hamburg-Eppendorf in Germany, and published in the American Journal of Hematology.

The primary endpoints were spleen size reduction and safety after irradiation. Secondary endpoints included days until neutrophil engraftment, days until platelet engraftment, relapse incidence, nonrelapse mortality, and overall survival (OS).

A total of 59 patients received splenic irradiation within a median of two weeks before HSCT, which led to a “significant and rapid spleen size reduction” in 97% of patients. The median decrease was 5 cm (95% CI).

The three-year OS was 62% (95% CI), and the one-year nonrelapse mortality was 26% (95% CI). Most (92%) patients achieved neutrophil engraftment within a median of 18 days after HSCT, and 81% achieved platelet engraftment within a median of 34 days after HSCT. Platelet counts decreased from a median of 92 × 109/L before irradiation to 45 × 109/L after irradiation.

Severe thrombocytopenia and anemia before irradiation, higher-intensity conditioning, and higher portal vein thrombosis were associated with worse outcomes.

Thrombocytopenia was the most frequent adverse event (AE), and three patients experienced nonhematological AEs.

When adjusting for confounders using a propensity score matching strategy, irradiation was associated with significantly reduced relapse (P=.01). The three-year incidence was 12% for irradiation before HSCT, 29% for patients with immediate HSCT, and 38% for patients receiving splenectomy.

“In conclusion, splenic irradiation immediately before HSCT is a reasonable approach in patients experiencing JAK inhibition failure and is associated with a low incidence of relapse,” wrote Dr. Gagelmann and colleagues.

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