FDA advisory panel votes against approval of Daiichi Sankyo's FLT3 inhibitor quizartinib in AML

Daiichi Sankyo said that eight members of an FDA advisory committee voted that results from a Phase III study do not support approval of quizartinib for the treatment of adults with relapsed/refractory FLT3-ITD acute myeloid leukaemia (AML). Meanwhile, three members of the panel voted that data from the QuANTUM-R trial demonstrate that the benefits of the oral FLT3 inhibitor outweigh the safety risks in this indication.

"While we are disappointed by the outcome…we will work closely with the FDA as it completes the review of our submission," remarked Antoine Yver, global head of oncology R&D at Daiichi Sankyo. The filing for quizartinib is currently under priority review, with the FDA expected to make a decision on approval by August 25 having extended its assessment of the application by three months earlier this year.

Data from the QuANTUM-R study presented last year at the European Hematology Association (EHA) congress showed that patients with relapsed/refractory AML with FLT3-ITD mutations who received single agent quizartinib had a 24 percent reduction in the risk of death compared to patients who received salvage chemotherapy. Results demonstrated that median overall survival was 6.2 months for patients treated with quizartinib and 4.7 months for those who received salvage chemotherapy.

At the FDA advisory panel meeting, several committee members noted that quizartinib did appear to bridge patients toward a transplant, which could potentially cure them, although they called for further study. "I believe in this drug but based purely on the data and evidence we were shown...I don't think this study has enough robust evidence," one panel member explained.

Regulatory filings for quizartinib are also under review in Europe and Japan, while the drug is also in Phase III development in combination with standard chemotherapy in newly-diagnosed FLT3-ITD AML, as well as in Phase I/II development for paediatric and young adult relapsed/refractory FLT3-ITD AML.

In related news, the same advisory committee panel voted 12 to 3 in support of approval of Daiichi Sankyo's pexidartinib for the treatment of adults with symptomatic tenosynovial giant cell tumour (TGCT). The FDA is scheduled to make a decision on whether to authorise the oral, small-molecule CSF1R inhibitor by August 3.


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