Kura Oncology and Kyowa Kirin Report Phase 2 Success for Leukemia Drug Ziftomenib

Kura Oncology and Kyowa Kirin have announced positive results from their phase 2 trial of ziftomenib, an oral selective menin inhibitor, in patients with relapsed or refractory NPM1-mutant acute myeloid leukemia (AML). The study met its primary endpoint, demonstrating a statistically significant improvement in complete response (CR) rate and partial hematological recovery (CRh).

Phase 2 Trial Results and FDA Submission Plans

The companies reported that the trial achieved its primary endpoint, although specific data were not disclosed. Kura and Kyowa Kirin confirmed their intention to file a new drug approval application with the FDA in the second quarter of 2025. The decision to withhold detailed data was attributed to conference rules, with plans to present topline findings at an upcoming medical meeting in the second quarter.

Analysts at Mizuho noted that the trial was powered to detect a CR/CRh rate of 20-30%, and the companies indicated that safety and tolerability were in line with previous data. This suggests that the results are likely within the "approvable" range for the FDA.

Upcoming Phase 3 Trials

In the second half of 2025, Kyowa and Kura will launch two phase 3 trials for ziftomenib:

1. A study combining ziftomenib with chemotherapy in AML patients with mutations in the NPM1 or KMT2A genes.
2. A trial testing ziftomenib in combination with Venclexta and Vidaza in NPM1 patients who are unfit to receive intensive chemotherapy.

Dr. Mollie Leoni, Kura's Chief Medical Officer, emphasized the urgent need for new treatments, stating, "Even with approved therapies, up to 70% of patients who achieve a first CR will see their AML return within three years."

Kyowa Kirin Partnership and Financial Details

Japan-based Kyowa Kirin invested $330 million upfront in 2024, with potential milestone payments of up to $1.1 billion, to partner with Kura on ziftomenib development. The collaboration involves shared responsibility for launching various trials in AML and other blood cancers over the next several years. Kura will fund the development of ex-U.S. trials until the end of 2028, after which the costs will be split between the two companies.

This partnership follows Kura's positive phase 1b data from early 2024, which suggested ziftomenib performed best when combined with a standard-of-care regimen in newly diagnosed patients with specific mutations.