Lilly acquires Ajax to advance next-gen myelofibrosis treatment
Drug also targets other blood cancers that don't respond well to existing therapies
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Two hands are shown clasped in agreement. (Photo by iStock)
Eli Lilly is acquiring Ajax Therapeutics to advance AJ1-11095, an experimental next-generation JAK2 inhibitor designed to deliver deeper, longer-lasting benefits for patients with myelofibrosis and other blood cancers that do not respond well to existing treatments.
“Lilly has long believed in the approach and is excited about the potential for AJ1-11095 to deliver deeper and more durable efficacy than available treatments,” Jacob Van Naarden, executive vice president and president of Lilly Oncology, said in a joint press release from the two companies. For Van Naarden, one advantage of AJ1-11095 is that it could be used “across both the first- and second-line settings.”
AJ1-11095 is being tested in an open-label Phase 1 clinical trial, AJX-101 (NCT06343805), in up to 76 adults with primary or secondary myelofibrosis who have previously been treated with other JAK2 inhibitors. The study will assess its safety and tolerability when taken orally once daily. The trial is still recruiting across Europe and the U.S., with the first data expected later this year.
“We look forward to the presentation of clinical proof-of-concept data later in 2026, rapidly advancing AJ1-11095 into registrational clinical trials, and using our expertise in blood cancer to hopefully deliver another important new medicine to patients and hematologists [blood specialists],” said Van Naarden, who is also head of corporate business development at Lilly.
AJ1-11095 designed to inhibit crucial enzyme
Myelofibrosis is a type of myeloproliferative neoplasm, a blood cancer that usually grows slowly. In myelofibrosis, the bone marrow starts producing too many abnormal blood cells, leading to ongoing inflammation and scarring. This can make it difficult for the bone marrow to produce healthy blood cells. Patients often develop an enlarged spleen, fatigue, and easy bruising or bleeding, among other symptoms.
AJ1-11095 is designed to inhibit JAK2, an enzyme that signals the production of blood cells. When this enzyme is overactive, it can cause blood cancer. Unlike approved type I JAK2 inhibitors, which bind to active JAK2, AJ1-11095 is a next-generation type II JAK2 inhibitor that binds to the enzyme in its inactive state. This is expected to inhibit signaling more effectively, overcoming resistance that often develops with type I JAK2 inhibitors.
In mouse models of myelofibrosis, AJ1-11095 normalized blood cell counts and reduced cancer-causing blood cells more effectively than Jakafi (ruxolitinib), an approved type I JAK2 inhibitor. It also reduced inflammation and scarring in the bone marrow without causing significant weight loss, suggesting it may be well-tolerated.
AJ1-11095 was the first type II JAK2 inhibitor to be cleared for clinical testing. Sponsored by Ajax, the ongoing AJX-101 clinical trial uses a dose-escalation design in which small groups of patients receive increasing doses of AJ1-11095 to identify the safest effective dose. The goal is to identify a maximum tolerated dose and then choose a recommended dose for future clinical testing.
In addition to testing AJ1-11095’s safety and efficacy in patients with primary myelofibrosis or secondary myelofibrosis (post-polycythemia vera myelofibrosis or post-essential thrombocythemia myelofibrosis) who have not responded to other JAK2 inhibitors, researchers are also measuring pharmacokinetics, or how AJ1-11095 moves into, through, and out of the body.
“With a small but highly motivated team, we have successfully applied this work to the design and development of our highly selective, first-in-class type II JAK2 inhibitor, AJ1-11095,” said Martin Vogelbaum, co-founder and CEO of Ajax. “We now look forward to Lilly advancing AJ1-11095 through the clinic.”
Under the agreement with Lilly, shareholders at Ajax could receive up to $2.3 billion in cash, including an upfront payment and additional payments if certain clinical and regulatory milestones are achieved. The agreement will be completed if the normal required conditions are met before closing.
