Celcuity Inc. (CELC) reported new Phase 3 data for gedatolisib, its targeted cancer candidate, showing longer disease control and higher response rates across several patient subgroups with advanced breast cancer. In one key analysis from the VIKTORIA-1 trial, patients without liver metastases who received the gedatolisib triplet went a median of 21.5 months without their disease progressing, compared with 9.1 months for the control regimen. In the PIK3CA-mutant cohort, the triplet produced a 59% overall response rate, compared with 33% for the control arm. The findings were presented at the European Society for Medical Oncology (ESMO) Congress on October 24, 2026, one of the field's largest international forums for cancer research. CELC shares nonetheless declined during the regular session and extended their losses after the closing bell.

Stock Slips Despite Positive Clinical Findings

Celcuity shares slipped 0.49% to $65.25, a decline of $0.32, during the regular session. The stock then lost another 1.39% in after-hours trading, reaching $64.34. The pullback followed a volatile session despite the company's latest clinical findings.

Celcuity develops targeted treatments for solid tumors, with gedatolisib central to its breast cancer program. Barbara Pistilli of Gustave Roussy presented the new PIK3CA-mutant subgroup results at the ESMO Congress.

The Phase 3 VIKTORIA-1 study tested gedatolisib combinations in patients with advanced HR-positive, HER2-negative breast cancer, the most common subtype of the disease. Researchers compared the gedatolisib regimens against existing treatment options, including alpelisib plus fulvestrant, a regimen already in clinical use for this setting. Phase 3 studies of this kind typically anchor the evidence companies present when seeking regulatory review, although the results here do not establish approval and support Celcuity's development plans in the first instance.

Longer Progression-Free Survival Across Subgroups

Median progression-free survival measures how long patients live without their disease worsening, making it a central gauge of whether a treatment delays cancer growth. Patients without liver metastases recorded 21.5 months of median progression-free survival on the gedatolisib triplet, compared with 9.1 months for the alpelisib and fulvestrant control group. The trial reported a hazard ratio of 0.46, corresponding to a 54% reduction in the risk of progression or death, and a p-value of 0.0016.

Among patients with liver metastases, the triplet delivered 9.1 months, versus 4.6 months for controls. The gedatolisib doublet achieved 11.1 months in that subgroup. Both reg showed statistically significant differences against the control in these patients.

Triplet recipients without visceral metastases reached 21.5 months, versus 9.2 months with standard treatment. Patients with visceral metastases recorded 9.8 months on the triplet, compared with 5.6 months for controls. The comparisons demonstrated benefits across disease locations, although subgroup sizes differed.

Higher Response Rates and Fewer Discontinuations

Overall response rate, the share of patients whose tumors shrink measurably, also favored the gedatolisib regimens. In the PIK3CA-mutant cohort, the triplet achieved a 59% response rate, compared with 33% for controls. The doublet produced a 43% response rate. Triplet responses lasted a median of 19.4 months, while the alpelisib combination recorded a median response duration of 7.5 months.

Celcuity also reported a 39% response rate for the triplet in patients with PIK3CA wild-type tumors. The doublet reached 34%, while fulvestrant alone reached 1%.

On safety, treatment-emergent adverse events prompted gedatolisib discontinuation in 5% of triplet patients and 4% of doublet patients. By contrast, 19% of patients discontinued alpelisib because of treatment-emergent adverse events. Discontinuation rates are closely watched because they indicate how well patients can tolerate a regimen over the course of treatment.

A separate analysis of eight trials also favored gedatolisib combinations over other regimens on progression-free survival measures. Together, the findings strengthen Celcuity's clinical development outlook, although indirect comparisons cannot replace direct head-to-head trials. Attention now turns to how Celcuity incorporates the VIKTORIA-1 results into its development plans and what further data or milestones the company outlines next.