Deciphera's investigational GIST drug ripretinib granted priority review by FDA

Deciphera Pharmaceuticals announced that the FDA will assess its filing for ripretinib under a priority review for the potential treatment of patients with advanced gastrointestinal stromal tumours (GIST). CEO Steve Hoerter stated that "with commercial preparations already underway, we believe we will be well positioned for a potential US launch in 2020." The regulator has set a target action date for the submission of August 13 this year. 

The filing is backed by data from the Phase III INVICTUS trial of 129 patients with advanced GIST whose previous treatments included at least Pfizer's Sutent (sunitinib), Bayer's Stivarga (regorafenib) and imatinib, which Novartis markets as Gleevec. Results presented last year showed that ripretinib met the study's primary endpoint of progression-free survival (PFS), with a median PFS of 6.3 months compared to 1 month for placebo. 

In addition, 9.4% of patients had a confirmed objective response with ripretinib compared to no confirmed responses in the placebo arm, although the result was not statistically significant. The KIT and PDGFR-alpha inhibitor also reduced the risk of death by 64% compared to placebo, demonstrating median overall survival (OS) of 15.1 months versus 6.6 months, respectively. However, since statistical significance had not been achieved for the secondary endpoint of objective response rate (ORR), Deciphera said hypothesis testing of OS was not formally performed. 

The FDA previously gave ripretinib a breakthrough therapy designation for the treatment of patients with advanced GIST who have received prior treatment with imatinib, Sutent and Stivarga. Deciphera also recently unveiled updated Phase I findings for ripretinib in patients with second-line through fourth-line-plus GIST, with ORRs ranging from 7% through 19%. 

In January, Blueprint Medicines' Ayvakit (avapritinib) became the first approved precision therapy for GIST in the US when the FDA approved it to treat adults with unresectable or metastatic GIST harbouring a PDGFR-alpha exon 18 mutation. The drug carries a list price of $32,000 for a 30-day supply, regardless of dosage. 

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