Eli Lilly announced on June 15 that its newly acquired JAK2 inhibitor, AJI-11095, demonstrated early efficacy in treating myelofibrosis, a rare chronic blood cancer. The results were presented at the European Hematology Association’s 2026 meeting and follow Lilly’s $2.3 billion acquisition of Ajax Therapeutics in April.
At the 12-week mark of a Phase 1 study, 70% of patients receiving AJI-11095 achieved a 35% reduction in spleen volume. The same proportion also experienced a 50% improvement in symptoms associated with myelofibrosis. Additionally, after 24 weeks of treatment, Lilly reported that 59% of patients showed at least a 20% decrease in driver mutation variant allele frequency—an indicator related to disease-causing genetic changes—with a reduction of at least half observed in 35% of patients.
BMO Capital Markets commented on Sunday evening that, “while still early, these data appear highly competitive.” The analysts added that AJI-11095 could become a “potentially best in class JAK2i.” They also described the safety profile as “clean,” noting manageable cases of treatment-emergent anemia and no dose-limiting toxicities or treatment-related dropouts. However, more than half the participants required dose reductions due to side effects.
Lilly is conducting an expansion cohort to evaluate AJI-11095 as a second-line therapy for myelofibrosis and plans additional studies for high-risk polycythemia vera and untreated myelofibrosis. According to Lilly, AJI-11095 works by binding to inactive JAK2 and more completely suppressing signaling pathways linked to overactive blood cell production.
The company also stated Saturday that preclinical models showed AJI-11095 had superior activity compared to ruxolitinib (marketed as Jakafi by Incyte) for myelofibrosis. Incyte CEO Bill Meury responded by saying, “I think that it’s an apples-and-oranges comparison... One’s a symptomatic therapy, optimizing or maximizing spleen volume reduction and symptoms versus potentially disease modifying therapy. I don’t think it’s an either or.”
Jakafi generated nearly $3.1 billion in sales during 2025 with an annual growth rate of 11%.
