Celcuity Trial Finds 21.5-Month Progression-Free Survival in Breast Cancer Subgroup

An updated phase 3 analysis of Celcuity Inc.’s VIKTORIA-1 trial found median progression-free survival of 21.5 months with its three-drug regimen among patients with PIK3CA-mutated cancer and no liver metastases, versus 9.1 months with control.

The results were presented Oct. 24 at the European Society for Medical Oncology Congress by Barbara Pistilli of Gustave Roussy. In the subgroup without liver metastases, median progression-free survival (PFS) was 21.5 months among 77 patients receiving gedatolisib, fulvestrant and palbociclib; 11.5 months among 28 receiving gedatolisib and fulvestrant; and 9.1 months among 76 receiving alpelisib and fulvestrant. The triplet’s comparison with control had a hazard ratio of 0.46 and a p-value of 0.0016. The doublet comparison was not statistically significant (p=0.1627).

For patients with liver metastases, median PFS was 9.1 months with the triplet, 11.1 months with the doublet and 4.6 months with control. Both treatment comparisons with control were statistically significant. Among patients with visceral metastases, median PFS was 9.8 months with the triplet and 11.3 months with the doublet, versus 5.6 months with control; both comparisons were statistically significant.

Among patients without visceral metastases, the triplet’s median PFS was 21.5 months, compared with 9.2 months for control (p=0.0059). The doublet’s median was not reached, versus 9.2 months for control, and its comparison was not statistically significant (p=0.0703).

Celcuity Chief Medical Officer Igor Gorbatchevsky described the results as showing “consistent and significant clinical benefit.” Among patients with evaluable disease, the combined confirmed and unconfirmed objective response rates were 59% with the triplet, 43% with the doublet and 33% with control. Median response duration was 19.4, 27.8 and 7.5 months, respectively. Treatment-emergent adverse events led to discontinuation for 5% of triplet patients and 4% of doublet patients, compared with 19% of patients receiving alpelisib.

The trial enrolled patients whose advanced cancer had progressed during or after treatment with a CDK4/6 inhibitor and an aromatase inhibitor. June results for the full PIK3CA-mutant cohort showed median PFS of 11.1 months with the triplet and 11.3 months with the doublet, compared with 5.6 months with control.

The Food and Drug Administration (FDA) approved gedatolisib with fulvestrant, with or without palbociclib, in July for adults with HR-positive, HER2-negative locally advanced or metastatic breast cancer without a detected PIK3CA mutation after progression following at least one endocrine therapy line in the metastatic setting. In August, Celcuity submitted an application seeking use in the PIK3CA-mutant HR-positive, HER2-negative locally advanced or metastatic population. The Oct. 24 update did not announce an FDA decision on that application.