Eli Lilly signed a definitive agreement to acquire Ajax Therapeutics, a privately held biotech developing JAK2 inhibitors for blood cancers, the companies announced on April 27, 2026. Ajax shareholders could receive up to $2.3 billion in cash.
The total includes an upfront payment and later payments tied to clinical and regulatory milestones. Neither company disclosed how the amount is split. The deal is subject to customary closing conditions, including clearance under the Hart-Scott-Rodino Antitrust Improvements Act.
Lilly will take over development of Ajax's lead drug, AJ1-11095. Ropes & Gray advised Lilly; Cooley advised Ajax, and Kirkland & Ellis also gave Ajax legal advice.
What Ajax built
Ajax, which has offices in New York and Cambridge, Massachusetts, develops drugs for myeloproliferative neoplasms (MPNs), a group of blood cancers that includes myelofibrosis and polycythemia vera. Its lead candidate, AJ1-11095, is a once-daily oral drug that the companies describe as a first-in-class Type II JAK2 inhibitor.
All approved JAK2 inhibitors for MPNs, such as Incyte's Jakafi, bind the Type I, or active, form of the JAK2 protein. Many patients stop these drugs because the benefit fades or the disease stops responding. AJ1-11095 binds the inactive form instead, which Ajax says could give deeper and longer-lasting disease control and offer an option for patients who become resistant to Type I drugs.
A Phase 1 trial, AJX-101, began in late 2024 in myelofibrosis patients previously treated with a Type I JAK2 inhibitor. A dose for further development is expected to be chosen in 2026, and Lilly plans to present first proof-of-concept data later in the year.
“We now look forward to Lilly advancing AJ1-11095 through the clinic and providing a much-needed new therapy for patients with MPNs.”
Why Lilly is buying
Jacob Van Naarden, president of Lilly Oncology and head of corporate business development, said Lilly hoped the drug would work better than existing treatments and be tolerated well enough for patients to stay on it longer, in both first- and second-line use. He said Lilly planned to move it quickly into registrational trials.
The purchase comes before Ajax has shown clinical proof of concept. RBC analyst Trung Huynh pointed out to BioPharma Dive that an earlier Lilly JAK2 inhibitor had failed, and described Lilly's strategy as buying differentiated assets before data readouts push their prices up.
JAK inhibitors are used for myelofibrosis and polycythemia vera, and also for immune conditions such as rheumatoid arthritis. BioPharma Dive noted that the existing drugs do not change the course of MPNs and have been linked to serious safety concerns. Lilly said many myelofibrosis patients stop treatment because their medicine stops working.
The founders and the funding
Ajax was founded in 2019 on the work of five scientific founders, including Ross Levine of Memorial Sloan Kettering Cancer Center, who chairs its scientific advisory board. Martin Vogelbaum is co-founder and chief executive. Schrödinger, whose computational drug-design platform Ajax uses, is its founding collaboration partner.
Ajax raised $40 million in June 2021 in a round led by EcoR1 Capital, with Boxer Capital, co-founding investors Inning One Ventures and Schrödinger, and research partners Memorial Sloan Kettering and NYU Langone Health. Cooley described that round as a Series B. In June 2024 Ajax closed a $95 million Series C led by Goldman Sachs Alternatives, with Lilly, RA Capital Management and Schrödinger among the investors. Vogelbaum said the company had a small team.
Lilly's run of deals
Ajax is one of several companies Lilly has agreed to buy in 2026. BioPharma Dive counted five acquisitions since the start of the year in cancer, immunology and brain disorders, four of them announced after the end of March. Stifel said 2026 was on course to be one of the busiest years on record for biotech and pharma deals.
The deal was announced in the same week as other large pharma transactions, including Sun Pharma's agreement to buy Organon and Ligand's purchase of Xoma Royalty. BioPharma Dive noted that Lilly had become the world's most valuable pharmaceutical company on the strength of its obesity and diabetes drugs.
