Lilly to Acquire Ajax Therapeutics for Next-Generation JAK2 Inhibitors in MPNs
Key claim: Eli Lilly is acquiring Ajax Therapeutics for $2.3 billion to develop AJ1-11095, a Type II JAK2 inhibitor in Phase 1 trials for myelofibrosis patients who have failed prior Type I JAK2 inhibitor therapy.
Abstract
Eli Lilly announced a definitive agreement to acquire Ajax Therapeutics, a company developing next-generation JAK inhibitors for MPNs. Ajax’s lead asset AJ1-11095 is a Type II JAK2 inhibitor being evaluated in Phase 1 for myelofibrosis patients previously treated with Type I JAK2 inhibitors. The deal is valued at $2.3 billion including upfront and milestone payments. Dose selection and proof-of-concept data expected in 2026.
Why this matters
Ruxolitinib failure remains a defining inflection point in PMF natural history, with limited options and poor outcomes after Type I JAK inhibitor discontinuation. A Type II JAK2 inhibitor like AJ1-11095 — locking JAK2 in an inactive conformation — represents a mechanistically distinct strategy that, if validated, could reshape post-ruxolitinib salvage for myelofibrosis specifically (vs. ET/PV where JAKi resistance is less central). The scale of Lilly’s commitment also signals industry conviction that PMF-specific drug development beyond Type I JAK inhibition is commercially and clinically viable.