A phase II study of single-agent nivolumab in patients with myelofibrosis was terminated early, after failing to meet its primary efficacy endpoint. Iman Abou Dalle, MD, from The University of Texas MD Anderson Cancer Center, and coauthors published these findings in the Annals of Hematology.
“Dysregulated JAK-STAT signaling in myelofibrosis induces pro-inflammatory cytokines, which suppresses T cell proliferation and differentiation, likely responsible for disease progression,” the authors explained. “The PD-1 pathway, found to be overexpressed in myeloid malignancies, has gained great interest as a therapeutic target, where a significant unmet need exists for novel therapeutic strategies.”
Based on findings from preclinical models which showed that JAK2 mutant cells had higher expression of PD-L1, investigators evaluated the efficacy and safety of single-agent nivolumab in eight adult patients with myelofibrosis.
Patients received nivolumab 3 mg/kg every two weeks for eight doses, then every 12 weeks for up to four years, or until disease progression or toxicity.
The median number of nivolumab doses received was six (range, 5-16). Five patients had stable disease including spleen size, total symptom score, and blood requirements, for a median of 3.3 months (range, 2.3-15.2 months).
After a median follow-up of 57 months, two patients were still alive, with a median overall survival of 6.1 months (range, 3.2-57.4 months). “Due to failure to meet the predetermined efficacy endpoint, the study was terminated early,” the authors concluded.