With an FDA decision looming in July, Celcuity said its lead drug gedatolisib met the primary endpoint of progression-free survival (PFS) against Novartis' PI3Kα inhibitor Piqray (alpelisib) in the PIK3CA-mutant cohort of its pivotal breast cancer study. The news drove company shares up around 16% Monday in premarket trading."VIKTORIA-1 represents the first Phase III study to demonstrate that comprehensively blocking the PI3K/AKT/mTOR, or PAM, pathway can significantly improve outcomes for patients with PIK3CA mutations compared to therapies only targeting a single component of this pathway," said co-principal investigator Sara Hurvitz.The study is investigating gedatolisib plus fulvestrant with or without Pfizer's Ibrance (palbociclib) in adults with hormone receptor (HR)-positive/HER2-negative locally advanced or metastatic breast cancer whose disease progressed on or after prior CDK4/6 therapy and an aromatase inhibitor. Participants with or without PI3KCA mutations are included in the trial.Last year, Celcuity reported data from the PIK3CA wild-type cohort showing a PFS benefit of 76% for the gedatolisib triplet regimen, compared to the fulvestrant arm, with median PFS of 9.3 months and 2 months, respectively (see – KOL Views Q&A: Celcuity's gedatolisib may be a bigger hit commercially than clinically in HR+ breast cancer). The findings set up an FDA marketing application, which was granted a priority review earlier this year and given a decision deadline of July 17.Celcuity said new topline results from VIKTORIA-1 show the gedatolisib triplet also significantly improved PFS compared to Piqray plus fulvestrant in PIK3CA-mutant patients with HR+/HER2- breast cancer.A second regimen pairing gedatolisib with fulvestrant alone also demonstrated a statistically significant benefit over Piqray plus fulvestrant, though this wasn't part of the primary efficacy analysis in the hierarchical order. Full data are slated for a late-breaking presentation at the upcoming American Society of Clinical Oncology (ASCO) conference.Celcuity indicated it plans to submit the new mutant-cohort data as part of a supplemental filing. HR+/HER2- breast cancer accounts for about 70% of all breast cancers, of which around 40% have PIK3CA mutations.Meanwhile, Novartis recently bolstered its focus on the PI3K pathway. In March, the Swiss pharma agreed to pay $2 billion upfront to acquire Pikavation Therapeutics and its pipeline of mutant-selective PI3Kα inhibitors.