Daiichi Sankyo will acquire Ambit Biosciences for up to about $410 million, the companies said today, in a deal that adds Ambit’s lead candidate—the Phase III cancer compound quizartinib—to the buyer’s portfolio of personalized oncology drugs.

Quizartinib (also called AC220) is in the Phase III QUANTUM-R trial (NCT02039726), whose primary objective is whether monotherapy using the compound prolongs overall survival (OS) compared to salvage chemotherapy in patients with acute myeloid leukemia (AML), who express a genetic mutation in FLT3 and who are refractory to or relapsed within six months after first-line treatment, with or without hematopoietic stem cell transplantation (HSCT) consolidation. The study’s estimated Primary Completion Date for primary-outcome data is November 2015, according to the trial’s page at ClinicalTrials.gov, last updated Sept. 23.

“Long-term success in oncology depends upon three pillars:  fostering development of our in-house molecules, exploring mutually beneficial partnerships and executing strategic purchases, such as Ambit Biosciences,” Joji Nakayama, Daiichi Sankyo’s president and CEO, said in a statement.

Nakayama noted that Daiichi Sankyo has built its cancer portfolio in part through earlier acquisitions: In 2011, Daiichi Sankyo acquired Plexxikon for $805 million upfront, plus another $130 million in milestone payments tied to approvals for Zelboraf (vemurafenib), an oral treatment co-developed with Roche for the BRAF mutation present in about half of melanoma cancers, and about 8% of solid tumors.

Three years earlier, Daiichi Sanko snapped up Germany’s U3 Pharma for €150 million ($235 million at the time but $190.5 million today). That deal boosted Daiichi Sankyo’s pipeline with U3’s lead product—patritumab (U3-1287 / AMG 888), a fully human anti-HER3 monoclonal antibody designed to inhibit oncogenic signaling and tumor proliferation, co-developed with Amgen and now in Phase II trials.

The acquisition by Daiichi Sankyo comes 18 months after quizartinib and Ambit suffered a setback when another Japanese pharma giant, Astellas Pharma, terminated a 2009 licensing agreement ending their collaboration for jointly developing and commercializing quizartinib and other FMS-like tyrosine kinase-3 (FLT3) inhibitors. Astellas had paid Ambit $40 million upfront, and agreed to pay pre-commercialization milestone payments of up to $350 million.

The termination came despite promising Phase II results released in 2012, showing that within two cohorts totaling 271 patients with relapsed or refractory AML who were positive for the FLT3-Internal Tandem Duplication (ITD) mutation, about half of each group achieved “composite complete response”—Complete remission, plus complete remission with incomplete platelet recovery, plus complete remission with incomplete hematologic recovery.

About one-third of the FLT3-ITD positive patients who had relapsed or were refractory after two prior lines of treatment, or after a prior HSCT received a potentially curative HSCT following treatment with quizartinib. As of September 28, 2012, 35 (18%) of FLT3-ITD positive patients had survived for more than 12 months.

Daiichi Sankyo agreed to pay Ambit shareholders approximately $315 million upfront through a tender offer followed by a merger with a Daiichi Sankyo subsidiary, plus one Contingent Value Right (CVR) valued at up to $4.50 cash for each share owned, tied to unspecified commercialization-related milestones. At $15 per share, the upfront portion reflects an 83% premium to Ambit’s closing share price of $8.20 on September 26.

The closing of the tender offer and merger is subject to conditions that include the tender of more than 50% of all shares of Ambit Biosciences.  Completion of the transaction is also subject to clearance under the Hart-Scott-Rodino (HSR) Antitrust Improvements Act and customary closing conditions.  The acquisition is expected to conclude promptly after receipt of HSR clearance and the close of the tender period. 

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