Eli Lilly continues its rapid pace of dealmaking, announcing the acquisition of Ajax Therapeutics to gain access to a clinical-stage therapy for myelofibrosis.
The centerpiece of the acquisition is AJ1-11095, a Type II JAK2 inhibitor currently being evaluated in a phase 1 trial launched in 2024. The study targets patients with this rare blood cancer who have previously been treated with Type I JAK2 inhibitors.
Existing therapies for myelofibrosis, such as Jakavi from Novartis and Incyte, as well as Inrebic from Bristol Myers Squibb, act by targeting the Type I conformation of the JAK2 protein. These treatments can help shrink spleen size and ease symptoms, but they are not believed to significantly alter the underlying disease biology.
Eli Lilly is betting that AJ1-11095’s mechanism – binding to the Type II conformation of JAK2 – could deliver more sustained and deeper clinical benefits. The approach may also offer a new treatment pathway for patients who develop resistance to currently available therapies.
Preclinical findings presented by Ajax Therapeutics at the American Society of Hematology Annual Meeting in December suggested that AJ1-11095 demonstrated stronger efficacy compared to Jakafi in models of myeloproliferative neoplasms, a group of conditions that includes polycythemia vera and myelofibrosis.
To secure the company and its lead asset, Eli Lilly agreed to a deal valued at up to $2.3 billion, including upfront payment and milestone-based compensation tied to development and regulatory progress, though specific financial details were not disclosed.
The pharma company already has experience in the JAK inhibitor space through Olumiant, developed in partnership with Incyte, which is approved for conditions such as rheumatoid arthritis and severe alopecia areata.
According to Jacob Van Naarden, president of Lilly Oncology, the company has long supported Ajax’s scientific approach and previously participated as an early investor, including in a $95 million funding round in 2024 alongside firms like Goldman Sachs Alternatives.
He noted that AJ1-11095 has the potential to deliver more durable responses while maintaining a tolerability profile that could enable longer treatment duration and use across both first- and second-line settings. He also highlighted expectations for initial clinical proof-of-concept data in 2026, followed by rapid progression into later-stage trials.
Ajax Therapeutics was established through a partnership with Schrödinger, building on research from Ross Levine, who serves as chief scientific officer at Memorial Sloan Kettering Cancer Center and played a key role in the company’s scientific foundation. Scientists from both organizations have worked closely together as an integrated team.
CEO Martin Vogelbaum said the company’s focused team successfully translated its research into the development of a highly selective, first-in-class Type II JAK2 inhibitor. He added that the team is now looking ahead to Eli Lilly advancing the therapy through clinical development with the goal of bringing a much-needed new option to patients with myeloproliferative neoplasms.
Powered by the cash injectionfrom Mounjaro, Eli Lilly has accelerated its acquisition strategy, striking a series of major deals, which include a $1 billion upfront purchase of gene-editing collaborator Verve Therapeutics and a $1.2 billion upfront acquisition of inflammation-focused biotech Ventyx Biosciences.
Why Lilly Targeted Ajax
The acquisition gives Lilly access to Ajax’s JAK inhibitor platform, which is designed to treat autoimmune and inflammatory diseases. By integrating these assets, Lilly aims to strengthen its position in a highly competitive therapeutic area.
Scientific Rationale Behind JAK Inhibitors
JAK inhibitors target the Janus kinase signaling pathway, which plays a central role in immune system regulation. By modulating this pathway, these therapies can reduce inflammation and are widely studied for conditions such as rheumatoid arthritis, psoriasis, and other autoimmune disorders. Their versatility makes them attractive assets in modern drug development.
Integration and Development Plans
Following the acquisition, the focus will likely shift toward integrating research teams, aligning development strategies, and advancing key candidates into later-stage trials. Efficient integration is critical to realizing the full value of such deals and accelerating timelines to potential commercialization.
Competitive Landscape in Immunology
The immunology space is highly competitive, with several major pharmaceutical companies investing heavily in next-generation therapies. Success depends on demonstrating improved safety profiles, better efficacy, or differentiated mechanisms compared to existing treatments.
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