Sunesis Pharmaceuticals has withdrawn the European Marketing Authorization Application (MAA) for its acute myeloid leukemia (AML) therapy candidate vosaroxin (Qinprezo™). The firm said that its communication with the European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) indicated that the committee would likely formally adopt a negative opinion recommending against approval of the drug, which had been submitted as a treatment for relapsed/refractor AML, in combination with cytarabine, in patients over 60 years of age. “Although we did not receive a definitive CHMP opinion, we believed that a positive opinion was unlikely,” admitted Daniel Swisher, Sunesis president and CEO.

The firm said it will now shift its financial focus to its kinase inhibitor pipeline, headed by SNS-062, a noncovalent reversible Bruton's tyrosine kinase (BTK) inhibitor licensed from Biogen Idec in 2014 that is expected to start in a Phase Ib/II study against B-cell cancers later this quarter. The firm will also keep vosaroxin development ticking over through what Swisher called “modest investment in investigator-sponsored group trials,” while also looking for “business development alternatives” to fund another pivotal study with the drug. Investigator-sponsored trials are ongoing to evaluate the anticancer quinolone derivative as a potential frontline therapy for AML and myelodysplastic syndrome (MDS).

The single pivotal VALOR trial with vosaroxin had failed to reach full statistical significance, and Swisher noted that the firm’s assessment following feedback from rapporteurs and regulatory experts concluded that “it was unlikely we could achieve a majority vote of CHMP members at this time or upon an immediate re-examination for our proposed indication based on VALOR data from a subgroup of a single pivotal trial.”

Both the FDA and the European Commission previously granted orphan drug designation to vosaroxin for the treatment of AML. The FDA also granted fast-track designation for vosaroxin as a potential treatment for relapsed/refractory AML in combination with cytarabine. 

The firm’s kinase inhibitor pipeline includes the preclinical candidates SNS-229 and SNS-510, which Sunesis licensed in from Millennium in 2014, but which had originally been developed as part of a research collaboration between Biogen Idec and Sunesis and licensed to Millennium in 2011.

TAK-580 (formerly MLN2480) is an oral pan-Raf kinase inhibitor, which Millennium Pharmaceuticals is developing under license from Sunesis. The drug is undergoing Phase Ib evaluation as combination therapy for advanced nonhematological cancers


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