Gedatolisib PDUFA preview: pan-PI3K/mTOR inhibitor targets HR+/HER2– breast cancer gap

On July 17, 2026, the FDA is expected to decide whether to approve gedatolisib, a first-in-class pan-PI3K/mTOR inhibitor developed by Celcuity, for the treatment of hormone receptor-positive (HR+), HER2-negative (HER2–), PIK3CA wild-type (WT) advanced breast cancer. The New Drug Application (NDA), which received priority review designation, is supported by progression-free survival (PFS) data from the PIK3CA wild-type cohort of the Phase 3 VIKTORIA-1 trial. If approved, gedatolisib would be the first PI3K/AKT/mTOR (PAM) pathway inhibitor available to patients regardless of PIK3CA mutation status, addressing a significant gap in the current treatment paradigm.

This preview is for oncology access teams, specialty pharmacy operators, payer medical directors, and breast cancer treatment navigators who need to understand gedatolisib's mechanism, clinical evidence, competitive positioning, and access implications ahead of the PDUFA date. It is not medical advice or reimbursement guidance for a specific patient or plan.

What gedatolisib is and how it works

Gedatolisib is an investigational, multi-target PAM pathway inhibitor that potently targets all four class I PI3K isoforms (p110α, p110β, p110γ, p110δ) as well as mTORC1 and mTORC2, achieving comprehensive blockade of the PI3K/AKT/mTOR signaling axis. This mechanism is fundamentally different from currently approved single-target PAM inhibitors.

The PAM pathway in breast cancer

The PI3K/AKT/mTOR (PAM) pathway is one of the most frequently dysregulated signaling cascades in cancer, driving uncontrolled cell proliferation, survival, and treatment resistance. In HR+/HER2– breast cancer — which accounts for approximately 70% of all breast cancers — PAM pathway activation occurs through multiple mechanisms:

• PIK3CA mutations (approximately 40% of HR+/HER2– tumors)
• PTEN loss or mutation
• AKT amplification or activation
• Upstream growth factor receptor signaling

Why comprehensive pathway blockade matters

Single-target inhibitors — such as alpelisib (PI3Kα-selective) and everolimus (mTORC1-only) — leave uninhibited pathway components that can drive tumor escape through cross-activation. Preclinical evidence demonstrates that gedatolisib's pan-isoform PI3K plus dual-mTORC inhibition provides equal potency and comparable cytotoxicity in both PIK3CA-mutant and PIK3CA-wild-type breast tumor cells, eliminating the adaptive resistance mechanisms that limit single-target approaches.

Key parameters:

The unmet need in HR+/HER2– breast cancer

HR+/HER2– is the most common breast cancer subtype, accounting for approximately 70% of all cases. Standard first-line treatment for advanced disease combines CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) with endocrine therapy (aromatase inhibitors or fulvestrant). Upon progression, treatment options narrow considerably:

• Alpelisib (Piqray) + fulvestrant: Approved only for PIK3CA-mutated disease (~40% of HR+/HER2– tumors). Patients with PIK3CA wild-type disease have no approved PI3K-targeted option.
• Everolimus + exemestane: mTORC1 inhibitor, but single-target and modest efficacy.
• Chemotherapy: Default for many patients after targeted options are exhausted.
• Enhertu (trastuzumab deruxtecan): For HER2-low or HER2-ultralow disease.
• Sacituzumab govitecan (Trodelvy): For triple-negative disease only.

The approximately 60% of HR+/HER2– advanced breast cancer patients whose tumors are PIK3CA wild-type have no approved PAM pathway-targeted therapy — the precise population for which gedatolisib's NDA is filed.

VIKTORIA-1 Phase 3 trial results

Study design

VIKTORIA-1 (NCT05501886) is a global, Phase 3, randomized, open-label clinical trial evaluating gedatolisib in combination with fulvestrant, with or without palbociclib, in patients with HR+/HER2– locally advanced or metastatic breast cancer who had progressed on or after prior endocrine therapy and a CDK4/6 inhibitor.

The trial enrolled two parallel cohorts based on PIK3CA mutation status:

• PIK3CA wild-type cohort: The NDA is based on this cohort. Patients were randomized to gedatolisib + fulvestrant + palbociclib (triplet), gedatolisib + fulvestrant (doublet), or standard-of-care physician's choice.
• PIK3CA mutant cohort: Patients were randomized 3:3:1 to gedatolisib triplet, alpelisib + fulvestrant (active comparator), or gedatolisib doublet. Positive topline data from this cohort were reported in May 2026.

PIK3CA wild-type cohort (NDA basis)

Celcuity reported that both gedatolisib-containing regimens demonstrated statistically significant and clinically meaningful improvements in progression-free survival compared to standard of care:

• Gedatolisib triplet (gedatolisib + fulvestrant + palbociclib): Reduced the risk of disease progression or death by 76% compared to fulvestrant alone (hazard ratio 0.24). Median PFS was 9.3 months versus 2.0 months with fulvestrant — an incremental improvement of 7.3 months.
• Gedatolisib doublet (gedatolisib + fulvestrant): Reduced the risk of disease progression or death by 67% compared to fulvestrant alone (hazard ratio 0.33). Median PFS was 7.4 months.

These results established new PFS benchmarks for PIK3CA wild-type HR+/HER2– advanced breast cancer in the post-CDK4/6 inhibitor setting.

PIK3CA mutant cohort

In the PIK3CA mutant cohort, gedatolisib-based combinations showed statistically significant and clinically meaningful improvement in PFS compared to alpelisib + fulvestrant (the SOLAR-1 regimen), with both the triplet and doublet arms outperforming the active comparator.

Safety and tolerability

The safety profile was characterized as favorable:

• Treatment discontinuation rates due to treatment-related adverse events were lower than those observed in the Phase 1b study and lower than those reported in any Phase 3 trials for currently approved drug combinations in HR+/HER2– advanced breast cancer.
• Hyperglycemia rates were lower than with alpelisib — a significant advantage given that hyperglycemia is the primary toxicity limiting alpelisib use (71% all-grade in SOLAR-1).
• Stomatitis was observed at a rate of approximately 69% (19% grade 3 or higher) in the VIKTORIA-1 trial, which is notable and comparable to or higher than rates seen with some single-target PAM inhibitors. Active management of stomatitis (mouthwashes, dose interruptions) will be important in clinical practice.
• Treatment discontinuation rates due to treatment-related adverse events were lower than those reported in any Phase 3 trials for currently approved drug combinations in HR+/HER2– advanced breast cancer, suggesting net tolerability is favorable despite stomatitis rates.

Context: alpelisib (Piqray) safety challenges

For comparison, the SOLAR-1 trial of alpelisib + fulvestrant reported that 71% of patients experienced hyperglycemia (grade 3/4 in 36.6%), and 25% of patients discontinued alpelisib due to adverse events. The BYLieve trial reported median PFS of 7.3 months in cohort A (post-CDK4/6 inhibitor + aromatase inhibitor). Gedatolisib's potentially improved tolerability profile and broader patient population eligibility represent key competitive advantages.

Competitive positioning

Gedatolisib vs. current PAM inhibitors

Key differentiators

1. Mutation-agnostic: Gedatolisib is the only PAM inhibitor under review that does not require a PIK3CA mutation for the proposed indication, potentially opening PAM pathway therapy to ~60% of HR+/HER2– patients who are PIK3CA wild-type.
2. Comprehensive blockade: Pan-PI3K plus dual-mTORC inhibition reduces adaptive resistance through cross-activation that limits single-target agents.
3. Combination flexibility: Demonstrated efficacy in both triplet (with palbociclib) and doublet (without) regimens gives prescribers flexibility.
4. Tolerability tradeoff: Lower hyperglycemia rates compared to alpelisib, but stomatitis requires proactive management. Net discontinuation rates were favorable versus comparators.

Sales forecast

Evaluate included gedatolisib in its top 10 drug launches for 2026, projecting sales of $2.1 billion by 2032. Pfizer originally developed gedatolisib but licensed it to Celcuity for $10 million upfront in 2021.

Access implications

Prior authorization

If approved, gedatolisib will require prior authorization across virtually all commercial and Medicare Part D plans. Expected PA criteria:

• Confirmed HR+/HER2– advanced or metastatic breast cancer
• PIK3CA wild-type status (for the initial indication) documented by an FDA-approved companion diagnostic
• Disease progression on or after CDK4/6 inhibitor + endocrine therapy
• Adequate organ function and performance status

Companion diagnostic requirement

The initial indication is limited to PIK3CA wild-type patients, creating an inverse companion diagnostic paradigm compared to alpelisib (which requires PIK3CA-mutant status). Payers may require documented negative PIK3CA mutation testing before authorizing gedatolisib, adding a step to the PA workflow. The FoundationOne CDx and similar NGS panels already include PIK3CA, so tissue availability rather than test access is the primary potential barrier.

Step therapy considerations

Payers may construct step therapy protocols that position alpelisib first for PIK3CA-mutant patients and gedatolisib for PIK3CA-wild-type patients, creating complementary rather than competing formulary positions. However, the VIKTORIA-1 mutant cohort data — showing gedatolisib outperforming alpelisib — could create payer pressure to reconsider this sequencing.

IV vs. oral route implications

As an IV infusion, gedatolisib introduces operational considerations distinct from oral PAM inhibitors:

• Buy-and-bill reimbursement: Providers purchase the drug and bill under the medical benefit (Part B for Medicare patients), rather than pharmacy benefit (Part D).
• J-code timeline: A permanent J-code may not be available at launch, requiring interim billing codes and potentially delaying reimbursement.
• Infusion center capacity: Additional infusion visits add to already constrained oncology infusion scheduling.
• Patient adherence: IV administration ensures delivery but requires regular clinic visits.

Specialty pharmacy and distribution

• Gedatolisib will be distributed through specialty distributors rather than traditional specialty pharmacy channels (due to IV formulation).
• REMS or restricted distribution programs have not been announced but will be clarified with the FDA label.
• Celcuity's expanded access program is already operational, providing early insight into the distribution infrastructure.

Ongoing and future development

The VIKTORIA-2 first-line trial expansion (announced May 14, 2026) is particularly significant. Phase 1b data in first-line patients showed a median PFS of 48.6 months with the gedatolisib + palbociclib + letrozole triplet, median overall survival of 77.3 months, and an objective response rate of 79% — results that compare favorably to current standard-of-care first-line regimens. If confirmed in VIKTORIA-2, the addressable patient population expands substantially beyond the current second-line-plus NDA.

Additionally, Phase 1b data in PIK3CA-mutant breast cancer showed median PFS of 14.6 months with continuous dosing and 19.7 months with an intermittent dosing regimen — results that support the potential for a future label expansion to include PIK3CA-mutant patients.

What to monitor next

Source table

Sources

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• Celcuity. "Our Pipeline." 2026. celcuity.com
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• Celcuity. "VIKTORIA-2 Expanding to Include Endocrine-Sensitive Patients." May 14, 2026. ir.celcuity.com
• Layman RM, et al. "Gedatolisib in combination with palbociclib and endocrine therapy in HR+/HER2– ABC." Lancet Oncology. 2024. celcuity.com (PDF)
• PMC. "Application of PI3K inhibitors in breast cancer treatment." 2026. pmc.ncbi.nlm.nih.gov
• ClinicalTrials.gov. "Phase 3 Study of Gedatolisib (VIKTORIA-2)." NCT06757634. clinicaltrials.gov
• ApexOnco. "ESMO 2025 – Celcuity fights for a share of the breast cancer market." 2025. oncologypipeline.com
• FirstWord Pharma. "Celcuity to Initiate NDA Submission of Gedatolisib in PIK3CA Wild-Type Cohort." August 2025. firstwordpharma.com
• Clinical Trials Arena. "Celcuity reports Phase III VIKTORIA-1 trial results for breast cancer." 2026. clinicaltrialsarena.com