Blueprint Medicines says its newly approved drug for a rare life-threatening disorder could be a blockbuster

The Cambridge biotech’s treatment combats an immune and blood condition that causes severe allergic reactions to ordinary things, like a whiff of perfume or an elevated heart rate

Kate Haviland is the CEO of Cambridge-based Blueprint Medicines.Brad Bahner/Blueprint Medicines

Suki Tipp had been stung by wasps before but never had a reaction like the one she experienced five years ago in a barn on her 30-acre property in Alabama.

After the sting to her right arm that July day, Tipp recalled, she had a metallic taste in her mouth and felt like her body was on fire. She rushed into her house to lie on an air-conditioning grate on the floor, then texted her husband outside as she grew weak. “Something’s not right,” she wrote. “I need help.”

Chad Tipp found his wife convulsing and foaming at the mouth. The 36-year-old mother of four had gone into anaphylactic shock, an acute and potentially lethal multisystem allergic reaction. He got her to a hospital, where the Troy, Ala., woman’s heart stopped three times and had to be restarted with defibrillator paddles. She received multiple shots of epinephrine and spent 10 days in the critical care unit.

Tipp didn’t have just an unusually bad allergic reaction. Within months she learned she was among an estimated 32,000 American adults with systemic mastocytosis, or SM. A rare immune and blood disorder resulting from a genetic mutation, it causes life-threatening allergic reactions to ordinary things ― a whiff of perfume, a taste of a tomato seed, an elevated heart rate from jogging.

On Monday, the Food and Drug Administration approved Ayvakit, a drug to treat a wide swath of SM patients.

Made by Cambridge biotech Blueprint Medicines, the medicine had been approved in 2021 for only a few thousand patients with an advanced form of the disease. That left most SM patients with no medication to prevent frequent and unpredictable allergic reactions.

Some had to keep an EpiPen to deliver a shot of epinephrine at arm’s length at all times. Others took antihistamines and weight-gaining steroids regularly. Some seldom left their homes, leading to depression.

“I have been waiting 25 years for this drug to happen,” said Dr. Mariana Castells, director of the Mastocytosis Center at Brigham and Women’s Hospital, who served as a principal investigator of a clinical trial of the drug.

The medication comes as a 25-milligram pill and must be taken daily. Ayvakit has a monthly wholesale cost of $37,111, which Blueprint intends to keep in place with expanded use. Blueprint says it plans to market it to the 7,500 patients diagnosed with moderate to severe cases of SM.

Kate Haviland, Blueprint’s chief executive, told analysts that the company projects peak sales of $1.5 billion a year, meaning that roughly half of the 7,500 patients in the target market would take it daily. A prescription drug that generates $1 billion in sales is considered a blockbuster. Ayvakit generated $111 million in sales last year.

SM “is a profoundly debilitating and complex disease that severely impacts patients’ ability to live their lives,” Haviland said. “This time of year, most of us are making plans to see family and friends. We are attending graduations, and we are scheduling summer vacations. These are the types of things that people living with [the disease] miss out on because they are fearful.”

SM’s unpredictable and potentially lethal allergic reactions stem from an overactive type of white blood cells called mast cells.

These cells play an important role in managing immune responses, and the human body ordinarily has millions of them, said Castells. People with SM have 10 to 100 times the normal amount, and they accumulate in parts of the body, such as the skin, heart, gut, bones, and other organs. The cells are easily activated, triggering inflammation where no problem exists.

Tipp, the woman stung by the wasp in 2018, said she never had any allergies until earlier that year, when she was 35. Suddenly, she began breaking out into hives. They were so itchy that she began scratching them in the middle of the night until they bled. Over-the-counter antihistamines didn’t help. The hives eventually left brown spots all over her skin.

A few months later, she began to notice the metallic taste in her mouth and started suffering gastrointestinal problems, such as when she had a sip of red wine. A whiff of someone wearing a deodorant at the supermarket would trigger allergic reactions. She had to administer an EpiPen to herself at least once a week, and sometimes as many as eight times. She eventually couldn’t leave her house because she was afraid of suffering from anaphylactic shock that could cause her airways to constrict and kill her.

A doctor at the MD Anderson Cancer Center in Houston ultimately diagnosed her with SM. In July 2021, she got into a clinical trial at the University of Alabama in Birmingham to test Blueprint’s drug. She takes it every night. She seldom has allergic reactions, she said, and hasn’t used an EpiPen in three months. Most important, she said, she feels comfortable leaving her house, and on Monday was thrilled to attend her son’s graduation from eighth grade.

“It’s been life-changing for me,” said Tipp, now 41. “I felt like I was living in a bubble.”

Castells, the Brigham researcher, said the drug works by reducing the number of mutated mast cells by 70 to 80 percent. The genetic mutation isn’t inherited, she added, but occurs at some point in people’s lives.

Ayvakit is one of two drugs Blueprint has on the market. It was originally approved in 2020 for an ultra-rare gastrointestinal cancer that afflicts hundreds of US patients. The mutated proteins that are the underlying causes of SM and the gastrointestinal tumors are similar in structure, according to the firm.

Salveen Richter, an analyst for Goldman Sachs, said in a note to investors Monday night that Blueprint is an attractive target for merger and acquisition, with a broad pipeline, including potential treatments for multiple forms of cancer.