US pharmaceutical company Eli Lilly and Company (NYSE:LLY) on Saturday announced new data from the Phase 1 AJX-101 study showing that its investigational type II JAK2 inhibitor (AJ1-11095) demonstrated an encouraging safety profile and promising clinical activity in patients with myelofibrosis who have been failed by a type I JAK2 inhibitor.

The company says that this first-in-class type II JAK2 inhibitor was designed to selectively bind the type II conformation of the JAK2 kinase in order to potentially provide greater efficacy than existing therapies and a novel treatment option for patients who become resistant to type I JAK2 inhibitors. Lilly recently added this programme to its pipeline following its acquisition of Ajax Therapeutics Inc.

These data will be highlighted in an oral presentation at the 2026 European Hematology Association (EHA) Annual Meeting taking place in Stockholm, Sweden.

AJX-101 is claimed to be the first clinical trial to evaluate a type II selective JAK2 inhibitor in patients with myelofibrosis. The trial enrolled 23 patients across five dose levels (25, 50, 75, 100, and 125 mg once daily) in its dose escalation phase. Patients had received a median of two prior therapies, and all had previously received a type I JAK2 inhibitor. The trial enrolled patients across all major myelofibrosis subtypes and driver mutations.

According to the company, the overall safety profile for the medicine was generally manageable. No dose-limiting toxicities were observed, and most patients enrolled in the dose escalation phase remain on study (78%). The most common treatment-emergent adverse events across all dose levels included anaemia, dysgeusia, decreased platelet count, and increased alanine aminotransferase.

AJ1-11095 is currently being evaluated in an expansion cohort in second-line myelofibrosis, with plans to investigate in patients with high-risk polycythaemia vera and those with myelofibrosis who have not yet received a JAK2 inhibitor.