With FDA approval, Celcuity sees big future for its new breast cancer drug

Brian Sullivan, CEO of Plymouth, Minnesota-based Celcuity, is convinced his biotech startup will soon provide the new standard of care for tens of thousands of breast cancer patients.

Last week, Celcuity won approval from the U.S. Food and Drug administration for a breast cancer therapy it calls Revtorpyk, but only for a limited number of cancer patients. The company aims to quickly expand the number of people eligible for the drug, including those with other forms of cancer.

So far the FDA approved the drug as part of a combination therapy with other medications for certain patients with advanced breast cancer, including for those with metastatic tumors in which the disease has spread to other parts of the body.

“We’ve demonstrated benefits that we believe justify becoming a standard of care,” Sullivan said. “We’re confident that this will be a blockbuster drug.”

It’s intended for patients with the common subtype of breast cancer known as HR+/HER2-, which accounts for about 70% of all breast cancer cases. Celcuity estimates Revtorpyk could tap into a $6 billion U.S. market for patients with that form of advanced breast cancer.

It’s approved for cancer patients without a common gene mutation, though the company hopes to expand that approval in coming months.

“This is an area of real unmet need,” said Sara Hurvitz , an oncologist at Seattle’s Fred Hutch Cancer Center who led the Revtorpyk clinical trials. “They’re dealing with an incurable state.”

The therapy, however, might not come cheaply. Celcuity has not released pricing information yet, but Sullivan said on an investor call that the drug will be priced at a premium relative to other available therapies.

Andrew Berens, a biotech analyst at Leerink Partners, wrote in an investor note that the drug may have a sticker price of $29,000 per month. Berens also estimated Revtorpyk would draw in $36.4 million in revenue for Celcuity in the 2026 fiscal year. It’s not yet clear whether insurance would cover the drug by the time it launches in September.

Revtorpyk is intended as a second-line therapy, for breast cancer patients whose first treatment plan proves ineffective, stops working or causes intolerable side effects. It’s administered intravenously at an infusion center weekly.

But Revtorpyk is not chemotherapy. In fact, for patients where a normal hormone therapy has stopped working, it’s designed to forestall the need for chemotherapy, which doctors try to delay because of extreme side-effects like fatigue, nausea and hair loss, said Matthew Goetz, a Mayo Clinic oncologist.

In recent clinical trials, a combination of Revtorpyk with another cancer drug and standard hormone therapy reduced the risk of disease progression by 76% compared to the hormone therapy alone. Patients on the triple-treatment saw a median of over nine months without their cancer developing, compared to two months on the hormone therapy.

When paired with hormone therapy on its own, which Goetz said is a more likely scenario outside clinical trials, Revtorpyk cut the risk of disease progression by 67% and raised progression-free times from two months to 7.4 months, the clinical trial data shows.

In both situations, roughly 30% of patients saw their tumors shrink, which is higher than what Goetz has seen for other cancer drugs.

With Revtorpyk, Celcuity will enter a crowded market for advanced breast cancer drugs, which includes treatments from major pharmaceutical companies like AstraZeneca, Novartis and Eli Lilly.

But Celcuity is optimistic that Revtorpyk’s positive trial results and innovative design speak for themselves.

Revtorpyk works by targeting a biological signaling pathway that normally controls cell growth and survival, but can cause cancer when unregulated.

In about 40% of HR+/HER2- breast cancer cases, a mutation in the PIK3CA gene acts like a jammed accelerator pedal, putting the pathway into a cancer-causing overdrive.

But Revtorpyk is one of the only FDA-approved second-line treatments for the remaining 60% of patients who don’t have the mutation, and for whom changes to other parts of the pathway still drive cancer.

Though most competitor drugs are only approved for patients with the mutation, Revtorpyk targets multiple parts of the pathway, which makes it more versatile, Hurvitz said.

Celcuity also plans to submit a supplemental application to the FDA this year to expand its approval to patients that have the PIK3CA mutation, as well.

For Hurvitz, part of Revtorpyk’s appeal is a reduced risk of side-effects. Unlike similar late-stage cancer drugs, her trial’s results showed lower rates of symptoms like high blood sugar, diarrhea and rash for patients on Revtorpyk.

But the drug wasn’t symptom-free. Almost three-quarters of patients experienced mouth ulcers and inflammation, which require patients to use a steroid-containing mouthwash four times a day to manage.

The symptoms prompted 12% of patients to stop the trial because of side effects — a higher-than-expected number that surprised analysts like Berens.

Analysts were also caught off guard by a delayed launch timeline for the drug this fall, Berens wrote in a note to investors. On an investor call, Sullivan said the company’s launch was intended to ensure adequate drug supply. But Wall Street’s concerns still sent Celcuity’s stock tumbling by over 15% after the company announced Revtorpyk’s FDA approval last week.

In an interview with the Star Tribune, Sullivan contested Revtorpyk’s launch as “delayed.” The company’s sales force is in the process of marketing to physicians and submitting approval to insurers, he said. Celcuity also plans to offer an expanded access program to let eligible patients receive treatment prior to market launch.

“There are people who are shorter-term oriented, and they’re trading the stock,” Sullivan said. “It just creates volatility. And that’s life and times.”

Despite runaway growth last year, the company’s clinical trial data on Revtorpyk for patients with the PIK3CA mutation disappointed investors.

Though the results were still “superlative,” Berens wrote, the delay in cancer growth was a few months shorter of what the company reported during earlier, smaller clinical trials. After the results were announced, Celcuity’s share price dropped by over 25%.

“I think Wall Street likes to see big splashy things and they set expectations on small numbers,” Hurvitz said. “And I think in science, the certainty around numbers improves when you have bigger numbers and better-defined populations.”

Celcuity is doubling down on Revtorpyk, the only drug in its portfolio, as a cancer-fighting Swiss army knife. The company sees Revtorpyk as a tool for prostate cancer, which shares a similar biology to breast cancer and represents an $8 billion market.

For breast cancer patients, the company is already conducting clinical trials exploring Revtorpyk as a first-line therapy for patients who haven’t yet received breast cancer treatment.

If the FDA grants Revtorpyk clearance for new breast cancer patients, Celcuity hopes to expand into a $10 billion market of about 130,000 patients.

“I’m very confident we’re going to really affect a lot of women’s lives because of the drug that we’re offering,” Sullivan said.