Phase II HOVON-134 final analysis: Pacritinib bridging in transplant-eligible MF

Final results from the prospective, single-arm, multicenter, phase II HOVON‑134 trial (NCT03645824), evaluating the feasibility of pacritinib bridging before allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with transplant-eligible myelofibrosis (MF; N = 61), were published in Bone Marrow Transplantation by Van Dijck et al. Feasibility was defined by concurrently meeting prespecified criteria: <70% Grade 3–4 adverse events (AEs), >30% pre-transplant symptom response, >20% pre-transplant spleen response, and ≥80% proceeding to their planned allo-HSCT, on or off protocol. 

Key data: The predefined feasibility criteria were met: Grade 3–4 AEs occurred in 44% of patients, symptom response occurred in 36%, spleen response occurred in 43% (n = 46 evaluable), and 95% proceeded to intended allo-HSCT. Median time to spleen response was 48 days, hemoglobin and platelet counts remained stable, and 69% of patients were able to tolerate pacritinib 200 mg twice daily throughout treatment. Gastrointestinal toxicity was the main AE, with Grade 3 events reported in 8% of patients and no Grade 4–5 cases; cardiac AEs were rare and no bleeding serious AEs (SAEs) were reported. Overall survival (OS) from registration was 80% (95% confidence interval [CI], 68–88) at 1 year and 57% (95% CI, 43–70) at 5 years. 

Key learning: Pacritinib appears to be a feasible bridging therapy before allo-HSCT in transplant-eligible MF, supporting its further evaluation and consideration in this clinical setting.