Ambit Still Committed to Leukemia Drug After Astellas Ends Pact

3/12/13Follow @bvbigelow

[Corrected 3/12/13, 11:55 pm. See below.] They say that breaking up is hard to do. Ambit Biosciences knows that it’s true.

After Japan’s Astellas Pharma said last night it had exercised its right to terminate their worldwide licensing agreement, Ambit spokesman David Schull says San Diego-based Ambit remains “fully committed” to moving ahead with mid-stage trials of its anti-cancer drug quizartinib. Just how Ambit will continue on its own isn’t clear, however.

Ambit has designated its lead drug candidate for patients who have a particularly aggressive form of acute myeloid leukemia (AML), and who have relapsed. Quizartinib targets a mutation in a kinase protein signaling pathway (FMS-like tyrosine kinase-3, or FLT3), which represents roughly a third of AML patients, or about 4,000 new cases a year.

In the statement issued overnight, Astellas CEO Yoshihiko Hatanaka says, “While our decision is based on strategic reasons, we are proud of our collaborative work with Ambit, and we are committed to working with Ambit on a smooth transition.”

The companies plan to work together to transfer current quizartinib development activities to Ambit before Sept. 3, when their partnership officially ends. At that time, Ambit regains all rights granted to Astellas, and plans to continue with the quizartinib clinical trial program. In an e-mail this morning, Schull says Ambit’s executives have had good visibility of the clinical trials managed by Astellas, which includes a mid-stage trial and two early stage studies, by participating in joint development meetings with Astellas.

Fierce Biotech’s John Carroll reports that cancellation means Astellas has walked away from its $40 million upfront payment, as well as a $350 million commitment in pre-commercialization milestone payments.

[Updated to deny speculation about timing of Ambit's IPO filing] While Astellas’ termination was announced today, the decision was likely made some time ago. In an earlier version of this story, I suggested that might help explain why Ambit said last month that it’s reviving its registration for an initial public offering. However, in a note this evening, Schull rejected that speculation as incorrect. Ambit yanked its previous IPO filing in mid-2011, after filing a registration in late 2010 with plans to raise more than $86 million.

Ambit CEO Michael Martino says in last night’s statement that the company and members of the medical community continue to be excited about quizartinib. But SEC rules preclude Martino from speaking while Ambit’s IPO is pending, Schull says in an e-mail this morning.

Schull notes that results of the mid-stage study results were presented at the American Society of Hematology’s Annual Meeting in December, saying the Phase 2 study demonstrated three key clinical benefits: A high response rate as a monotherapy in relapsed AML patients with the FLT3 mutation; A substantial number of patients made the transition to bone marrow transplantation; and an improved overall survival rate compared with historical data.

Bruce V. Bigelow is the editor of Xconomy San Diego. You can e-mail him at bbigelow@xconomy.com or call (619) 669-8788 Follow @bvbigelow

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