Celcuity shares fall as launch delay eclipses US approval for breast cancer drug

Shares of Celcuity fell nearly 19% in morning trading on Wednesday, as the delayed commercial launch of its newly approved breast cancer drug and label concerns overshadowed the company's first U.S. approval.

The U.S. Food and Drug Administration on Tuesday approved gedatolisib, branded as Revtorpyk, for certain patients with advanced breast cancer whose tumors do not carry a PIK3CA mutation. Celcuity expects to begin marketing the drug in the third quarter.

Revtorpyk, combined with Pfizer's Ibrance and fulvestrant, reduced the risk of disease progression or death by 76% in a late-stage trial.

Patients receiving the treatment went through a median 9.3 months without their cancer worsening, compared with two months for those receiving fulvestrant alone.

Revtorpyk's label showed that 12% of patients receiving the three-drug combination stopped treatment due to side effects.

The label warns that Revtorpyk can cause severe mouth inflammation and recommends preventive mouthwash. Mouth inflammation occurred in 72% of patients receiving the three-drug combination, including severe cases in 22%.

The ability of doctors to effectively manage the inflammation and keep patients on drug will be critical to commercial success, said Leerink's Berens.

At least two analysts said the safety label did not change their view of the drug's market potential.

Citizens Bank analyst Silvan Turkcan expects Revtorpyk to cost about $28,000 per month, and models $36 million in sales in 2026.

While the approval was largely expected, the company's delayed launch was not anticipated, given prior commentary on launch readiness, said Leerink Partners analyst Andrew Berens.