Celcuity's Phase 3 VIKTORIA-1 Trial Meets Primary Endpoint With Clinically Meaningful Improvement In Progression-Free Survival In PIK3CA Mutant Cohort; Celcuity Intends To Submit These Data To The FDA As A Supplemental New Drug Application And To Submit VIKTORIA-1 Data To Other Regulatory Authorities Following The sNDA Submission

Celcuity Inc. (NASDAQ:CELC), a clinical-stage biotechnology company pursuing development of targeted therapies for oncology, today announced positive topline results from the PIK3CA mutant cohort of the Phase 3 VIKTORIA-1 clinical trial evaluating gedatolisib plus fulvestrant with or without palbociclib in patients with hormone receptor positive ("HR+"), human epidermal growth factor receptor 2 negative ("HER2-"), PIK3CA mutant locally advanced or metastatic breast cancer ("ABC"), following progression on or after treatment with a CDK4/6 inhibitor and an aromatase inhibitor. Detailed results will be presented in a late-breaking abstract ("LBA") oral session at the American Society of Clinical Oncology ("ASCO") Annual Meeting, taking place May 29 – June 2, 2026, in Chicago, Illinois.

The primary efficacy analysis of gedatolisib combined with fulvestrant and palbociclib (the "gedatolisib triplet") demonstrated a statistically significant and clinically meaningful improvement in progression-free survival ("PFS") compared to alpelisib, a PI3Kα inhibitor, and fulvestrant. The secondary endpoint comparing gedatolisib plus fulvestrant (the "gedatolisib doublet") versus alpelisib plus fulvestrant, which was not part of the primary efficacy analysis in the hierarchical order, also demonstrated a statistically significant and clinically meaningful improvement in PFS compared to alpelisib and fulvestrant. Both gedatolisib regimens were generally well tolerated, with manageable safety profiles, and no new safety signals.

Celcuity intends to submit these data to the U.S. Food and Drug Administration (the "FDA") as a supplemental New Drug Application ("sNDA") and to submit VIKTORIA-1 data to other regulatory authorities following the sNDA submission.

"Patients with PIK3CA mutant HR+/HER2- advanced breast cancer whose disease has progressed while on or after treatment with a CDK4/6 inhibitor typically derive modest benefit from subsequent therapies that target only PI3Kα or AKT," said Sara Hurvitz, MD, Senior Vice President, Clinical Research Division, Fred Hutch Cancer Center, Smith Family Endowed Chair in Women's Health and Professor and Head, Division of Hematology and Oncology, University of Washington, School of Medicine and co-principal investigator for the trial. "VIKTORIA-1 represents the first Phase 3 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."

HR+/HER2- breast cancer is the most common subtype of breast cancer, accounting for approximately 70% of all breast cancers.2 Among this breast cancer subtype, approximately 40% have PIK3CA mutations.