Splenic irradiation for myelofibrosis prior to hematopoietic cell transplantation: A global collaborative analysis.

Splenomegaly is the clinical hallmark of myelofibrosis. Splenomegaly at the time of allogeneic hematopoietic cell transplantation (HCT) is associated with graft failure and poor graft function. Strategies to reduce spleen size before HCT especially after failure to Janus kinase (JAK) inhibition represent unmet clinical needs in the field. Here, we leveraged a global collaboration to investigate the safety and efficacy of splenic irradiation as part of the HCT platform for patients with myelofibrosis. We included 59 patients, receiving irradiation within a median of 2 weeks (range, 0.9-12 weeks) before HCT. Overall, the median spleen size prior to irradiation was 23 cm (range, 14-35). Splenic irradiation resulted in a significant and rapid spleen size reduction in 97% of patients (57/59), with a median decrease of 5.0 cm (95% confidence interval, 4.1-6.3 cm). The most frequent adverse event was thrombocytopenia, with no correlation between irradiation dose and hematological toxicities. The 3-year overall survival was 62% (95% CI, 48%-76%) and 1-year non-relapse mortality was 26% (95% CI, 14%-38%). Independent predictors for survival were severe thrombocytopenia and anemia before irradiation, transplant-specific risk score, higher-intensity conditioning, and present portal vein thrombosis. When using a propensity score matching adjusted for common confounders, splenic irradiation was associated with significantly reduced relapse (p = .01), showing a 3-year incidence of 12% for splenic irradiation versus 29% for patients with immediate HCT and 38% for patients receiving splenectomy. In conclusion, splenic irradiation immediately before HCT is a reasonable approach in patients experiencing JAK inhibition failure and is associated with a low incidence of relapse.

Allogeneic Stem Cell Transplantation for Patients with Lower-Risk Myelodysplastic Syndrome.

The indication for allogeneic stem cell transplantation (SCT) in patients with lower-risk myelodysplastic syndrome (MDS) is controversial. Here we report 60 patients with a low risk (n = 32) or intermediate risk (n = 28) classification according to the revised International Prognostic Scoring System (IPSS-R) who underwent allogeneic SCT with a reduced-intensity conditioning (n = 45) or myeloablative conditioning (n = 15) regimen from an HLA-identical sibling (n = 9), a matched unrelated donor (n = 36), or a mismatched unrelated donor (n = 15). The rates of grade II-IV and grade III-IV acute graft-versus-host disease were 32% and 7%, respectively, resulting in a transplantation-related mortality (TRM) of 17% at 3 years. The cumulative incidence of relapse at 5 years was only 7%, resulting in a 5-year disease-free survival of 72% and overall survival (OS) of 79%. Transplantation from a fully matched donor resulted in significantly improved OS at 5 years (91% versus 70%). Allogeneic SCT in lower-risk MDS (IPSS-R low or intermediate risk) from an HLA-matched donor resulted in excellent OS with a low risk of relapse.