Celcuity (NASDAQ:CELC) said its VIKTORIA-1 Study 2 met its primary endpoint in patients with hormone receptor-positive, HER2-negative, PIK3CA-mutated advanced breast cancer who had progressed after treatment with a CDK4/6 inhibitor and an aromatase inhibitor.
On a conference call, Chief Executive Officer and co-founder Brian Sullivan said both gedatolisib-based regimens “doubled the likelihood of a patient’s survival without disease progression or death” compared with alpelisib plus fulvestrant. Gedatolisib is Celcuity’s investigational pan-PI3K/mTOR inhibitor.
VIKTORIA-1 Study 2 Results
The primary analysis compared the gedatolisib triplet with alpelisib plus fulvestrant. Hurvitz said the triplet produced a statistically significant and clinically meaningful reduction in the risk of disease progression or death, with a hazard ratio of 0.50. Median progression-free survival was 11.1 months for the triplet.
The gedatolisib doublet also showed a clinically meaningful reduction in the risk of progression or death versus alpelisib plus fulvestrant, with a hazard ratio of 0.51 and median progression-free survival of 11.1 months. Hurvitz said the descriptive P value for the doublet comparison was 0.0013.
Celcuity executives said the alpelisib plus fulvestrant control arm showed median progression-free survival of roughly 5.5 to 5.6 months, depending on the comparison cited during the call.
Response and Safety Data
Hurvitz said overall response rates, clinical benefit rates and disease control rates were higher for the gedatolisib-based regimens than for alpelisib plus fulvestrant. She said the 49% objective response rate for the gedatolisib triplet was, to her knowledge, higher than previously reported by any Phase 3 trial for a regimen including endocrine therapy in the second-line HR-positive, HER2-negative advanced breast cancer setting.
The median duration of response was 15.7 months for the gedatolisib triplet compared with 7.5 months for alpelisib plus fulvestrant, Hurvitz said. She also said the duration of response was tripled with the doublet compared with the control arm.
Safety results were generally consistent with the individual agents in each regimen, with no new safety signals reported. Treatment discontinuations due to adverse events were 2.6% for the gedatolisib triplet, 3.8% for the gedatolisib doublet and 7.1% for alpelisib plus fulvestrant. Hurvitz said there were three Grade 5 events deemed related to treatment by investigators: one in the gedatolisib triplet arm and two in the alpelisib plus fulvestrant arm.
Hurvitz said rates of diarrhea and hyperglycemia, which are associated with PI3K inhibition, were much lower in the gedatolisib arms than in the alpelisib plus fulvestrant group. She cited hyperglycemia of 58% and diarrhea of 40% for alpelisib plus fulvestrant. Stomatitis was among the most common treatment-related adverse events for gedatolisib-based treatment.
Physician Perspective and Treatment Positioning
Dr. Sara Tolaney, chief of breast oncology at Dana-Farber Cancer Institute, said she was “very impressed” with the data, calling the post-CDK4/6 inhibitor PIK3CA-mutated population challenging to treat. She said current regimens such as fulvestrant plus capivasertib have shown progression-free survival of about 5.5 months in the post-CDK population.
“This, in essence, is doubling compared to control therapy, what we’re able to achieve in terms of disease control,” Tolaney said.
Tolaney also highlighted the low discontinuation rate. “We never get a discontinuation rate this low with a PI3K inhibitor,” she said, adding that current treatments can require glucose monitoring and management of diarrhea and rash.
During the question-and-answer session, Sullivan said Celcuity believes both the triplet and doublet could be appropriate options, particularly in the PIK3CA-mutated setting where the doublet performed better than the company expected. He said the company plans to seek label expansion for use regardless of PIK3CA status, while noting that regulatory discussions remain ahead.
Commercial and Regulatory Update
Eldon Mayer, Celcuity’s chief commercial officer, said the company is preparing for a potential launch of gedatolisib. He estimated that about 37,000 U.S. patients with HR-positive, HER2-negative advanced breast cancer receive second-line treatment each year after progression on CDK4/6 inhibitors, with roughly 60% PIK3CA wild type and 40% PIK3CA mutant.
Mayer said Celcuity estimates a $6 billion total served market opportunity across both PIK3CA wild-type and mutant patient populations. He said the company has completed payer engagements covering 90% of U.S. medical benefit lives and has built out its sales, medical affairs, distribution and patient support infrastructure.
Sullivan said Celcuity expects an FDA approval decision by its PDUFA date of July 17, 2026, for the VIKTORIA-1 PIK3CA wild-type cohort. He also said the company is targeting submission of a supplemental new drug application to the FDA in the third quarter and a marketing authorization application to the European Medicines Agency in the fourth quarter.
About Celcuity (NASDAQ:CELC)
Celcuity, Inc is a clinical-stage biotechnology company specializing in precision oncology diagnostics. The company develops and commercializes predictive biomarker assays designed to identify which patients are most likely to benefit from targeted cancer therapies. By integrating functional profiling of tumor cells with molecular analyses, Celcuity seeks to optimize treatment selection and improve outcomes for patients with solid tumors.
Celcuity’s proprietary platform evaluates tumor cell sensitivity to various therapeutic agents using ex vivo assays that measure DNA damage response and other critical pathways.
