Lilly’s Ajax Data Signals Early Breakthrough Potential in Myelofibrosis Treatment
Eli Lilly has shared the first clinical dataset supporting its $2.3 billion acquisition of Ajax Therapeutics, presenting results at the European Hematology Association (EHA) 2026 annual meeting. The company evaluated its Type II JAK2 inhibitor AJ1-11095 in a phase 1 study focused on patients with myelofibrosis who had previously failed treatment with Type I JAK inhibitors. The early readout matters because it directly tests whether Lilly’s scientific hypothesis can translate into meaningful clinical benefit in a heavily pretreated population.
AJ1-11095 Shows Rapid Spleen Reduction and Symptom Relief in Early Trial Results
The phase 1 AJX-101 trial tested AJ1-11095 across 25–125 mg dose cohorts in myelofibrosis patients. The drug showed a 70% SVR35 response rate (16/23 patients) and significant symptom improvement, with 70% achieving ≥50% symptom score reduction at week 12 and 65% maintaining it at week 24. Overall, 96% of patients experienced symptom relief at some point, indicating strong and consistent clinical activity.
Beyond Symptoms: Myelofibrosis Trial Reveals Mutational Burden Reduction with AJ1-11095
Beyond symptom control, the therapy also demonstrated effects on disease biology. The study reported reductions in driver mutation variant allele frequency in 21 of 23 patients. Among those who reached week 24, 59% achieved at least a 20% reduction, while 35% recorded a reduction of 50% or more. These findings matter because they suggest the drug may not only manage symptoms but also influence the underlying disease-driving mutations across JAK2, MPL, and CALR profiles.
Safety Findings in Focus: Anemia and Liver Enzyme Signals in Lilly’s JAK2 Program
The safety data showed no dose-limiting toxicities during dose escalation. However, 52% of patients experienced grade 3 or higher anemia, while 30% reported grade 3 or higher platelet reductions. Importantly, most participants already entered the study with anemia, which affects interpretation of hematologic adverse events. Five discontinuations occurred, but none were linked directly to drug toxicity, including cases related to transplant, logistics, non-response, or unrelated events.
Competitive Pressure Mounts as Lilly Challenges Incyte in Myelofibrosis Market
The results arrive in direct competitive context with Incyte, which continues to develop mutation-targeted therapies such as INCA033989 for CALR-mutated myelofibrosis. Earlier phase data for Incyte showed SVR35 rates around 27.6% in previously treated patients and 31.3% overall best responses, with symptom improvement in a lower proportion compared to Lilly’s early readout. As a result, Lilly’s dataset places pressure on existing treatment benchmarks in the post-JAK inhibitor setting.
Why Type II JAK2 Inhibition Could Reshape the Future of Myelofibrosis Therapy
Lilly designed AJ1-11095 to selectively target the Type II conformation of JAK2, a mechanism intended to differentiate it from existing Type I JAK inhibitors such as Jakafi. The company believes this approach could expand activity across multiple mutation subtypes while maintaining tolerability. Moreover, early biomarker signals such as VAF reduction support the hypothesis that this mechanism may influence both clinical symptoms and disease biology.
Lilly Moves Fast: Phase 3 Planning Accelerates After Strong Ajax Early Data Readout
Lilly is fast-tracking its myelofibrosis program after promising Ajax data, moving toward Phase 3 in second-line treatment. While 75 mg continues in expansion, the 125 mg dose is limited by liver enzyme signals. The company is also exploring broader use in polycythemia vera and JAK2-inhibitor–naïve myelofibrosis, aiming to position AJ1-11095 as a potential next-generation standard of care.
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Source: Fiercebiotech.Com