Around 22,000 people across the U.S. have a rare chronic condition called indolent systemic mastocytosis. It can manifest itself in a number of ways, from skin conditions to anaphylactic events to cognition, which can also make it challenging to get a diagnosis. Last May, the FDA approved the first-ever treatment: avapritinib, marketed by pharma company Blueprint Medicines as Ayvakit. It was a watershed moment for the small community of patients that had previously only been able to treat specific symptoms and not the disease. On its 4th quarter earnings call last week, Blueprint announced that it now has over 1,000 ISM patients prescribed with Ayvakit already. The drug, which lists for about $445,000 a year, brought in $204 million in revenue in 2023, nearly double the $110 million it brought in last year. (The drug is approved for other indications as well.) The company announced with its earnings that it expects between $360 - 390 million in product revenue for the drug this year, and the company expects this to keep growing over the next few years as the drug finds its way into the hands of patients. “We see this as being a $2 billion plus market,” CEO Kate Haviland told Forbes. The reason for that being the number of patients who could benefit from the drug, particularly because Ayvakit actually treats the root cause of ISM, not just its symptoms, and so far, she added, the safety profile has proven to be better than the previous standard of care. “It’s so important for these patients, who didn’t realize how much they had narrowed their lives until they got on the therapy,” she said. “They’re able to reclaim their life again.”