Blueprint gears up for Ayvakit expansion, with blockbuster sales on the line

Stomach cancer may be a bust for Blueprint Medicines’ Ayvakit, but now the kinase inhibitor is nearing a potential FDA label expansion in a rare blood disorder. The company hopes this use can catapult the drug into blockbusterland.

Blueprint is expecting an FDA decision to expand Ayvakit’s current approval in advanced systemic mastocytosis (SM) into the indolent form of the disease by May 22. If approved, Ayvakit would be the first FDA-approved therapy for indolent SM, representing a potential paradigm shift for this rare disease.

Advanced SM, where Ayvakit is currently approved, only accounts for 5% to 10% of all SM cases. With an approval in indolent SM, the drug could reach $1.5 billion in annual peak sales in SM, according to Blueprint, up from $111 million in 2022.

Meanwhile, the company is already laying the groundwork for the important launch.

Blueprint’s field force is out talking with doctors, and the company’s “greatest focus” is on the top 350 providers who are regularly seeing about 1,500 moderate to severe indolent SM patients, chief commercial officer Philina Lee said during Blueprint’s fourth-quarter earnings call Thursday. Overall, Blueprint’s targeting about 7,500 U.S. moderate to severe patients who are not well controlled on their current treatments.

Blueprint also wants to persuade new patients to consider Ayvakit as their initial treatment. Already, a Blueprint campaign has enrolled thousands of “highly motivated prospective patients” who may have SM, Lee said.

Thirdly, Blueprint aims to maintain smooth access to the therapy. All doses of Ayvakit currently face “virtually no access challenges” and enjoy “industry-leading time to fill,” Lee said.


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As for how Ayvakit sales will ramp, Lee drew a comparison to the hereditary angioedema (HAE) market, another rare disease with around 7,500 diagnosed and treated patients in the U.S. In 2021, combined global sales of prophylactic HAE therapies—such as Takeda’s Takhzyro—were $1.5 billion, Lee noted.

As was the case with HAE drug launches, Blueprint doesn’t expect immediate uptake. Still, the company's ongoing efforts to increase disease awareness and diagnosis should help spur adoption and growth, Lee said.

For 2023, Berenberg analysts project $165 million in total Ayvakit sales, including about $30 million from indolent SM.

For its part, Blueprint expects 2023 Ayvakit sales between $130 million to $140 million. The number doesn't factor in a potential expansion into indolent SM.

Ayvakit may face competition down the line, including from Cogent Biosciences’ in-class candidate bezuclastinib. But a disease expert Berenberg talked with argued that latecomers will face significant hurdles because doctors often develop a familiarity with first-comer drugs.

Detailed data from the positive PIONEER trial for Ayvakit in indolent SM will be shared at the upcoming American Academy of Allergy, Asthma and Immunology meeting starting next week. Previously, top-line data that Blueprint shared in August showed a weaker-than-expected improvement for Ayvakit on a total symptom score. While an approval still seems likely, some analysts questioned whether the data could translate into strong adoption.

Editor's Note: A previous version of the story stated that the high-volume doctors Alnylam's focusing on treats about 15,000 patients. It should be 1,500 patients.