- Boston-based Blueprint Medicines on Thursday won its first-ever drug approval, securing clearance from the Food and Drug Administration for its genetically targeted cancer therapy Ayvakit in an ultra-rare type of tumor known as GIST.
- The decision from the FDA came about five weeks ahead of schedule and vaults Blueprint into the ranks of commercial-stage biotechs. Ayvakit will cost $32,000 for a 30-day supply, a premium price that's similar to what Bayer charges for its cancer drug Vitrakvi.
- Ayvakit's approval only covers the roughly 6% of patients with GISTs, or gastrointestinal stromal tumors, whose cancer tests positive for a specific mutation in the DNA of nerve cells lining the walls of the gastrointestinal tract. About 5,000 new cases of GIST are diagnosed in the U.S. each year, meaning the group of patients eligible for Ayvakit likely numbers in the hundreds.
Ayvakit's approval, the first from the FDA in 2020, is in keeping with recent trends.
Since 2017, the regulator has approved about two dozen cancer drugs that target a type of enzyme known as kinases, a therapeutic class of which Ayvakit (avapritinib) is a part. Kinase inhibitors can dramatically shrink tumors, yielding at times impressive benefits in treated patients.
Persuaded by that efficacy, and by the ability to genetically identify patients who are likely to benefit, the FDA now regularly approves kinase inhibitors based on early response rate data, sometimes from studies that lack a placebo comparison.
Ayvakit's approval, for example, is supported by results from 43 patients given Blueprint's drug. All were diagnosed with GIST that was either inoperable or that had spread to other parts of the body, and tested positive for a mutation in a specific strip of a gene called PDGFRA.
Thirty-six participants in the Phase 1 study experienced tumor responses, including three who went into remission.
Median duration of response, a measure of how long the drug kept tumors in check, was not yet reached, with some patients experiencing responses beyond one year.
Likely making the FDA's decision easier is the fact that GIST cancers with mutation targeted by Blueprint don't respond to standard treatments, like Novartis' drug Gleevec (imatinib) or Pfizer's Sutent (sunitinib). Research cited by the biotech found none of 31 studied patients with the most common type of PDGFRA mutation benefited from Gleevec.
Blueprint is also seeking approval for Ayvakit in GIST, broadly defined, that's progressed following three or more lines of therapy. The FDA, however, split Blueprint's application, approving the drug in PDGFRA-mutated GIST while setting up a separate decision in fourth-line treatment.
Currently, the agency is set to decide on that second part by Feb. 14, but that could be pushed back by three months to allow Blueprint to submit data from a Phase 3 study testing Ayvakit against Bayer's Stivarga (regorafenib) in third- or fourth-line GIST.
Only four years passed between when Blueprint asked the FDA to allow human testing for Ayvakit to the drug's approval, a rapid timeline that reflects the advantages of studying genetically targeted drugs in small subsets of patients.
Blueprint plans to submit applications for Ayvakit in advanced systemic mastocytosis, a disease in which a type of white blood cell accumulates in the skin and organs.
The biotech is also developing another targeted cancer drug called pralsetinib in lung cancers spurred to growth by a genetic abnormality called RET fusions.
Blueprint shares rose 5% Friday morning on the news of Ayvakit's approval.