A cancer drug developed by Blueprint Medicines could help treat a rare and debilitating disease called systemic mastocytosis, results from two trials announced by the Cambridge, Massachusetts-based biotech on Tuesday show. Treatment with Ayvakit, which was approved by the Food and Drug Administration in January for an uncommon type of gastrointestinal tumor, significantly reduced the proliferation of mast cells throughout the body, addressing the cellular cause of the chronic and unpredictable symptoms that people with systemic mastocytosis experience. Blueprint plans to ask the FDA to expand Ayvakit’s use to allow for treatment of systemic mastocytosis sometime during the fourth quarter, a step that would further boost the company’s drug pipeline. Shares in Blueprint rose by nearly 10% on the news, pushing the company’s market value toward $5 billion.
In July, Blueprint agreed to a deal with Swiss drugmaker Roche, licensing rights to a targeted cancer therapy called pralsetinib in return for $675 million in cash. Soon after, the companies received a fast approval from the FDA, putting the drug, now dubbed Gavreto, onto the market in the U.S.
Speaking to investors in July, Blueprint’s CEO pitched the deal, and its cash infusion, as a path to the company’s financial independence and an opportunity to invest in itself. The results released Tuesday suggest the bet was not misplaced, showing Blueprint’s pipeline can deliver beyond Gavreto and Ayvakit’s niche cancer indication.
Systemic mastocytosis is driven by a mutation in cells known as KIT D816V, leading to the activation and spread of mast cells in organs like the liver and spleen, as well as in the bone marrow. In advanced or severe cases, this proliferation of mast cells can lead to blood cancer or death.
Ayvakit works to block the effects of KIT D816V mutations and the results released Tuesday show most patients given the drug responded.
In one early study, called EXPLORER, treatment with Ayvakit led to responses in three quarters of the 53 treated patients. Measured at the median, those responses lasted 38 months.
New on Tuesday was initial data from a Phase 2 trial called PATHFINDER, which supported the first study’s findings. Three quarters of the 32 patients included in the analysis responded to the drug, although follow-up was more limited.
In both cases, the median overall survival was not yet estimable, meaning more than half of the patients are still alive and suggesting the drug helps extend survival. Blueprint cited data that in advanced cases of systemic mastocytosis, or in cases when the disease leads to blood cancer, median overall survival can range from as little as six months to roughly three and a half years.
There are no approved systemic mastocytocis treatments that specifically target D816V mutant KIT. A Novartis drug called Rydapt is used to treat cases of the disease currently, but has a response rate of only 28%, according to Blueprint.
Importantly, changes made by Blueprint to how Ayvakit is dosed appears to have made treatment safer. Previous data had shown that high drug doses were associated with elevated risk of intracranial bleeding in patients with severely low platelet counts, which can be present alongside systemic mastocytosis.
In response, Blueprint excluded patients with pre-existing severe thrombocytopenia from the two trials and added routine platelet monitoring as part of treatment guidelines.
Two patients among the 76 treated in EXPLORER and PATHFINDER with the new guidelines, and at a lower drug dose, experienced Grade 1 and asymptomatic intracranial bleeds, Blueprint said.
The company will present detailed data from the two trials at an upcoming medical conference.
Following the Roche deal this summer, Wall Street analysts described Ayvakit’s use in systemic mastocytosis, as well as progress from an earlier-stage Blueprint cancer drug, as key factors in the company’s continued growth. With the data Tuesday, Blueprint appears on its way to accomplishing the first.
