Lilly reports positive early data for JAK2 inhibitor in myelofibrosis

Eli Lilly and Company is presenting Phase 1 clinical findings for AJ1-11095, a first-in-class type II JAK2 inhibitor, at the 2026 European Hematology Association Annual Meeting in Stockholm. The drug targets patients with myelofibrosis who have previously failed to respond to standard type I JAK2 therapies.

The AJX-101 study enrolled 23 patients who had received a median of two prior therapies. Findings indicate significant clinical activity, with 70% of participants achieving a spleen volume reduction of at least 35% and a 50% improvement in symptom burden by week 12. Notably, 21 of the 23 patients showed reductions in driver mutation variant allele frequency, a marker rarely impacted by existing type I inhibitors.

John Mascarenhas, principal investigator of the study, noted that the results suggest a differentiated approach for patients with limited options. Jacob Van Naarden, president of Lilly Oncology, described the depth of response across spleen, symptoms, and mutation burden as exceeding historical benchmarks for this disease setting. The drug was acquired through Lilly’s recent purchase of Ajax Therapeutics and is currently moving into expansion cohorts, with future plans to investigate its efficacy in polycythemia vera and treatment-naive myelofibrosis patients.