High Response Rate for Axatilimab in Recurrent, Refractory GVHD

A recent study published in the New England Journal of Medicine on September 19, 2024, highlights the efficacy of the colony-stimulating factor 1 receptor (CSF1R)-blocking antibody, axatilimab, in treating patients with recurrent or refractory graft-versus-host disease (GVHD). The study, led by Dr. Daniel Wolff from University Hospital Regensburg in Germany, focused on evaluating different doses of axatilimab in a phase 2 clinical trial.

The trial involved patients who had recurrent or refractory chronic GVHD. Participants were randomly divided into three groups to receive axatilimab intravenously at doses of 0.3 mg, 1 mg, or 3 mg per kilogram of body weight. The administration schedules were every two weeks for the 0.3 mg and 1 mg doses, and every four weeks for the 3 mg dose, with each group consisting of 80, 81, and 80 patients respectively. The primary goal was to observe the overall response rates within the first six treatment cycles, which included both complete and partial responses.

The results of the study were promising across all dose groups. The overall response rates were 74%, 67%, and 50% for the 0.3 mg, 1 mg, and 3 mg dose groups, respectively. Additionally, the study assessed the impact on patient symptoms using the modified Lee Symptom Scale. A reduction of more than 5 points on the scale was noted in 60%, 69%, and 41% of patients in the 0.3 mg, 1 mg, and 3 mg dose groups, respectively.

However, the study also reported some adverse events. The most common side effects were dose-dependent transient laboratory abnormalities linked to the blockade of CSF1R. Despite these, the study successfully met its primary endpoint, demonstrating the efficacy of axatilimab in eliciting an overall response in 50% to 74% of patients across the three different dosage groups.

The research received funding from Incyte and Syndax Pharmaceuticals, companies involved in the manufacture and licensing of axatilimab. The study's findings provide critical insights into potential treatment options for patients suffering from recurrent or refractory GVHD, highlighting axatilimab as a viable therapeutic candidate.

In conclusion, this phase 2 study underscores the potential of axatilimab in treating chronic GVHD, showing significant response rates and manageable side effects across different dosage levels. The promising outcomes from this research could pave the way for further clinical developments and offer hope to patients grappling with this challenging condition.