Why CELC Stock Declined 15% in a Week Despite a Major FDA Win

Celcuity CELC recently entered a new chapter in its corporate journey after securing FDA approval for its first marketed product. The regulatory milestone marked the company's transition from a clinical-stage biotech to a commercial-stage enterprise. Despite this landmark achievement, the stock has declined about 15% over the past week.

Last week, the FDA approved two Revtorpyk (gedatolisib)-based combination therapies to treat adults with HR-positive, HER2-negative, PIK3CA wild-type (non-mutant), locally advanced or metastatic breast cancer following progression on or after endocrine therapy in the metastatic setting. One approved regimen combines the drug with AstraZeneca's AZN Faslodex (fulvestrant) and Pfizer's PFE Ibrance (palbociclib), while the other pairs it with Faslodex.

The approval also makes Revtorpyk the first therapy to inhibit all class I PI3K isoforms (α, β, δ, γ) and mTOR complexes mTORC1 and mTORC2, enabling comprehensive inhibition of the PI3K/AKT/mTOR (PAM) pathway, a key driver of cancer cell growth and survival. However, investors appeared underwhelmed by Celcuity's commercialization timeline.

While management reiterated plans to launch Revtorpyk in the third quarter of 2026, it clarified that the commercial rollout would begin only in the late third quarter to ensure sufficient drug inventory. The later-than-expected rollout appears to have disappointed investors, as it delays the start of commercial sales and near-term revenue generation.

The delayed launch comes despite Revtorpyk's significant commercial potential. Per Celcuity, nearly 37,000 patients in the United States with HR-positive/HER2-negative advanced breast cancer receive second-line treatment each year following progression on CDK4/6 inhibitors, representing a commercial opportunity exceeding $6 billion. About 60% of these patients have PIK3CA wild-type tumors, while the remaining 40% harbor PIK3CA mutations.

The FDA's approval is supported by results from the PIK3CA wild-type cohort of the phase III VIKTORIA-1 study. Data from the study showed that the triplet and doublet regimens reduced the risk of death or disease progression by 76% and 67%, respectively, when compared to Faslodex alone.

Year to date, shares of Celcuity have lost 12% against the industry's 2% growth.

While Revtorpyk's initial approval is currently limited to PIK3CA wild-type patients, Celcuity is already working to expand the drug's addressable market. The company plans to submit a regulatory filing in the third quarter of 2026 seeking a label expansion for the drug in PIK3CA-mutant patients.

The label expansion will be supported by data from the PIK3CA mutant cohort of the VIKTORIA-1 study, which achieved its primary endpoint. The two Revtorpyk regimens cut the risk of disease progression or death by nearly half compared to Novartis' NVS Piqray (alpelisib) plus Faslodex, which is considered the standard of care in this indication.

Celcuity is also developing Revtorpyk for the first-line setting. The company is evaluating the drug in the ongoing phase III VIKTORIA-2 study, which includes two independent studies in patients with HR-positive/HER2-negative locally advanced or metastatic breast cancer who are treatment-naive in the advanced setting. Celcuity is also studying Revtorpyk for metastatic castration-resistant prostate cancer, providing additional opportunities to broaden the drug's commercial potential.

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Celcuity currently has a Zacks Rank #4 (Sell). You can see the complete list of today's Zacks #1 Rank (Strong Buy) stocks here.

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