FDA again delays Daiichi's plans to challenge Astellas and Novartis for blood cancer market

Daiichi Sankyo’s long wait for approval of quizartinib just grew a little longer. Having bounced back from a 2019 rejection, the Japanese drugmaker has now learned the FDA needs another three months to review its second attempt to launch a challenger to Astellas and Novartis in a blood cancer market. 

The latest delay to the approval of the FLT3 inhibitor will give the FDA time to review requested updates to the proposed Risk Evaluation and Mitigation Strategies (REMS), Daiichi said. No additional efficacy or safety data are required. If everything goes to plan for Daiichi, the REMS request will be a blip rather than a disaster and only push back the approval date to July 24.

In a statement, Mark Rutstein, M.D., global head of oncology clinical development at Daiichi, said the company is “continuing to work with the FDA to facilitate completion of their review of the quizartinib new drug application in order to bring this important medicine to patients as soon as possible,” adding that the drug candidate improved overall survival (OS) in an acute myeloid leukemia (AML) clinical trial.

That study could be the salvation for quizartinib. When Daiichi filed for approval the first time, the FDA, following the lead of its advisory committee, rejected the candidate amid concerns about the credibility of the clinical trial data. Daiichi won approval in Japan around the time the FDA issued its rejection.

Seeking to get a return on the $315 million it paid upfront for quizartinib developer Ambit Biosciences, Daiichi kept looking for a route to market and found one last year when the drug improved OS in AML patients with the FLT3-ITD mutation. Daiichi packaged the data up into a submission for FDA approval that could see quizartinib belatedly emerge as a challenger to Novartis’ Rydapt and Astellas’ Xospata.

The two incumbent drugs target the same gene mutation as quizartinib. Astellas forecasts (PDF) that sales of Xospata could top out at 200 billion Japenese yen ($1.5 billion). Sales of the drug grew (PDF) 41% over the first nine months of Astellas’ financial year, but neither it nor Novartis’ Rydapt are nearing blockbuster status yet.