Celcuity Inc. (NASDAQ:CELC) shares dropped 15% on Tuesday even after the company released detailed positive efficacy and safety findings from the PIK3CA-mutant cohort of its Phase 3 VIKTORIA-1 study evaluating gedatolisib in patients with hormone receptor-positive, HER2-negative, PIK3CA-mutated advanced or metastatic breast cancer.
The decline came despite data showing significant improvements in progression-free survival and disease control compared with current treatment options.
Gedatolisib Triplet Therapy Delivers Strong Efficacy Results
According to the study results, treatment with gedatolisib in combination with fulvestrant and palbociclib reduced the risk of disease progression or death by 50% compared with alpelisib plus fulvestrant.
Patients receiving the gedatolisib-based triplet therapy achieved a median progression-free survival of 11.1 months, nearly double the 5.6 months reported in the comparator group.
The findings suggest the regimen may offer a meaningful improvement for patients with this specific breast cancer subtype.
Doublet Therapy Also Shows Significant Benefit
The study also evaluated gedatolisib combined with fulvestrant without palbociclib.
Results showed that the doublet regimen lowered the risk of disease progression or death by 49% compared with alpelisib plus fulvestrant.
Median progression-free survival reached 11.3 months in the gedatolisib-plus-fulvestrant group, compared with 5.6 months for patients treated with alpelisib and fulvestrant.
The consistency of the results across both treatment approaches reinforced confidence in the drug’s therapeutic potential.
Response Rates and Durability Remain Encouraging
Beyond progression-free survival, the trial also demonstrated strong tumor response outcomes.
The gedatolisib triplet regimen produced an objective response rate of 48.9%, with a median duration of response of 15.7 months.
Meanwhile, the gedatolisib doublet achieved a 35.7% objective response rate and an even longer median duration of response of 24.2 months.
These results indicate that many patients experienced sustained clinical benefit from treatment.
Favorable Safety Profile Observed
Investigators reported that the gedatolisib-based regimens were generally well tolerated.
Most treatment-related adverse events were low grade, and discontinuation rates due to treatment-related side effects remained comparatively low.
Treatment-related adverse events resulted in discontinuation for 2.6% of patients receiving the gedatolisib triplet, 3.8% of patients receiving the gedatolisib doublet, and 7.1% of patients treated with alpelisib plus fulvestrant.
The lower discontinuation rates may strengthen the drug’s competitive position if approved.
Regulatory Submissions Planned
Celcuity said it plans to submit the new clinical data to the U.S. Food and Drug Administration as part of a supplemental New Drug Application, while also pursuing submissions to regulatory agencies in other markets.
The company is already advancing regulatory efforts for gedatolisib in another breast cancer indication.
The FDA has granted Priority Review status to Celcuity’s New Drug Application for gedatolisib in patients with HR-positive, HER2-negative, PIK3CA wild-type advanced breast cancer.
The application carries a Prescription Drug User Fee Act (PDUFA) target decision date of July 17, 2026.
Investors Focus on Future Commercial Prospects
Although the latest data demonstrated strong efficacy and a favorable safety profile, investors appeared to take profits following recent gains or reassess expectations around the commercial opportunity and regulatory pathway.
Nevertheless, the VIKTORIA-1 results further strengthen the clinical case for gedatolisib and provide additional evidence supporting its potential role in the treatment of advanced breast cancer.
With an FDA decision approaching and further regulatory submissions planned, Celcuity remains focused on advancing the therapy toward commercialization and expanding its presence in the oncology market.