The Moffitt Cancer Center has reported promising results from a phase 1 trial investigating fedratinib (Inrebic) as a maintenance therapy following allogeneic hematopoietic cell transplantation in patients with myeloproliferative neoplasms (MPNs). The study established 400mg daily as the maximum tolerated dose, marking a significant step forward in post-transplant care strategies.
Safety Profile and Dosing Outcomes
The trial employed a traditional 3+3 dose escalation design, starting at 200mg daily and incrementing to the FDA-approved pre-transplant dose of 400mg. Twelve patients received treatment between 60 to 100 days post-transplant, continuing for up to one year. The primary endpoint focused on determining the maximum tolerated dose.
"While transplant can be curative, the cure rate is generally in the 40% to 60% range," explained Dr. Hany Elmariah, associate member at the Moffitt Cancer Center. "The main reason patients are not cured by transplant is largely the risk of relapse."
The observed toxicities aligned with expectations, primarily manifesting as cytopenias. While one patient experienced grade 4 thrombocytopenia necessitating treatment discontinuation, most adverse events were manageable. Gastrointestinal side effects remained mild to moderate, with no cases of Wernicke's encephalopathy reported due to proactive thiamine monitoring.
Efficacy and Disease Control
The trial revealed compelling dose-dependent responses in both relapse prevention and GVHD control. At the highest dose level of 400mg, none of the six patients experienced relapse during the reporting period. This contrasted notably with lower dose cohorts, where three out of three patients at 200mg and one out of three at 300mg relapsed.
The JAK2 inhibitor also showed promise in mitigating graft-versus-host disease, with no cases of moderate-to-severe chronic GVHD observed at higher dose levels. This dual benefit addresses two critical challenges in post-transplant care: disease recurrence and transplant complications.
Future Implications and Clinical Applications
The findings support further investigation of fedratinib as a standard maintenance therapy, particularly for specific patient populations. "Patients with a JAK2 mutation seem to have a better response, so we might focus on those patients moving forward," noted Dr. Elmariah.
The drug's potential application extends beyond major transplant centers to community oncology practices, where many patients receive their follow-up care. This accessibility could facilitate broader implementation of post-transplant maintenance strategies, potentially improving long-term outcomes for MPN patients.
The success of this initial trial has set the stage for larger phase 2 studies, with the ultimate goal of conducting randomized phase 3 trials to definitively establish fedratinib's role in post-transplant maintenance therapy.
