Gedatolisib for HR-positive, HER2-negative advanced breast cancer
Celcuity Inc· VIKTORIA-2
Reviewed by Blane Jackson, DDS, MBA. Educational analysis only. Read the editorial policy and disclosures.
NCT06757634 on ClinicalTrials.gov →Study type
interventional
Design
Randomized, open-label, parall…
Target enrollment
1,180
Est. completion
2029-03-31
Investor scorecard
Probability of success
moderate
Timeline to catalyst
The trial is expected to complete in March 2029. However, interim analyses may be conducted earlier, possibly around 2027-2028, depending on event rates. Investors should watch for announcements of interim results or early termination for efficacy.
Potential stock impact
transformativeThe probability of success is moderate. The trial is well-designed and based on promising phase 1b data. However, the competitive landscape is intense, with several other targeted agents in development. The addition of gedatolisib to palbociclib and endocrine therapy may increase efficacy but also adds toxicity, which could affect compliance and tolerability. Historical precedent suggests that adding a PI3K/mTOR inhibitor to CDK4/6 inhibitors has been challenging due to overlapping toxicities. The open-label design may introduce bias, but the primary endpoint is objective. Overall, there is a reasonable chance of success, but not a high one.
What is being tested?
This trial is testing a new drug called gedatolisib, which is a type of targeted therapy known as a PI3K/mTOR inhibitor. It works by blocking certain proteins that help cancer cells grow and survive. The drug is being combined with existing treatments for advanced breast cancer that is hormone receptor-positive (HR+) and HER2-negative (HER2-). This type of breast cancer relies on hormones like estrogen to grow. The trial aims to see if adding gedatolisib to standard treatments (palbociclib plus an aromatase inhibitor or fulvestrant) improves outcomes compared to the current standard of care, which is ribociclib plus the same endocrine therapies.
How does the trial work?
This is a phase 3, randomized, open-label trial. Patients with HR+/HER2- advanced breast cancer who have not received prior systemic treatment for their advanced disease are enrolled. They are randomly assigned to one of four treatment arms: Arm A receives gedatolisib plus palbociclib and fulvestrant; Arm B receives ribociclib and fulvestrant; Arm C receives gedatolisib plus palbociclib and letrozole; Arm D receives ribociclib and letrozole. The trial is open-label, meaning both patients and doctors know which treatment is being given. Patients receive treatment until disease progression or unacceptable toxicity. The trial will follow patients for several years to measure outcomes like progression-free survival and overall survival.
What does success look like?
Success would be demonstrated if the gedatolisib-containing arms show a statistically significant improvement in progression-free survival compared to the ribociclib-containing arms. For example, in the PALOMA-2 trial, palbociclib plus letrozole improved median PFS to about 24.8 months versus 14.5 months for placebo plus letrozole. In the MONALEESA-2 trial, ribociclib plus letrozole improved median PFS to about 25.3 months versus 16.0 months for placebo. To be considered a success, gedatolisib combinations would need to show a meaningful improvement over these benchmarks, perhaps extending median PFS by several months or more, with an acceptable safety profile.
What it means for investors
For investors, a successful VIKTORIA-2 trial could be transformative for Celcuity, the sponsor. If gedatolisib shows a clear PFS benefit over ribociclib, it could position gedatolisib as a new first-line standard of care for HR+/HER2- advanced breast cancer, potentially capturing a significant share of a multi-billion dollar market. Positive results could lead to regulatory submissions and approval, driving substantial revenue growth. Conversely, if the trial fails to show superiority or shows excessive toxicity, it could be a major setback, potentially causing the stock to drop significantly. Investors should watch for interim analyses or early signals, but the primary completion is expected in 2029, so near-term catalysts may be limited. The probability of success is moderate, given the competitive landscape and the challenges of combining multiple targeted agents.
Trial endpoints
Primary endpoints
Secondary endpoints
Comparator
Ribociclib (Kisqali) plus endocrine therapy (fulvestrant or letrozole)
Competitive landscape
The market for first-line treatment of HR+/HER2- advanced breast cancer is substantial. Approximately 70% of breast cancers are HR+/HER2-. In the advanced setting, there are over 100,000 new cases annually in the US and EU combined. Current standard of care includes CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) combined with endocrine therapy. The global market for CDK4/6 inhibitors alone exceeded $10 billion in 2023. If gedatolisib can demonstrate improved efficacy, it could capture a significant portion of this market, potentially reaching multi-billion dollar sales. However, competition is intense, with several other targeted agents in development.
| Drug | Sponsor | Phase | Differentiation |
|---|---|---|---|
| Inavolisib (with palbociclib and fulvestrant) | Roche/Genentech | Phase 1 | Inavolisib is a PI3K inhibitor specifically targeting the alpha isoform, while gedatolisib is a pan-PI3K/mTOR inhibitor. Inavolisib is being tested in the INAVO120 trial in the same first-line setting. |
| Capivasertib (with fulvestrant) | AstraZeneca | Phase 1 | Capivasertib is an AKT inhibitor approved for HR+/HER2- breast cancer with PIK3CA/AKT1/PTEN alterations, but it is used in the second-line setting, not first-line. |
| Alpelisib (with fulvestrant) | Novartis | Phase 1 | Alpelisib is a PI3K inhibitor approved for HR+/HER2- advanced breast cancer with PIK3CA mutations, but it is used in the second-line setting. |
Historical context
Prior trial results
Gedatolisib has been evaluated in earlier phase trials. In a phase 1b trial, gedatolisib combined with palbociclib and fulvestrant showed promising activity in heavily pretreated HR+/HER2- advanced breast cancer, with an objective response rate of about 25% and a clinical benefit rate of 50% in patients who had progressed on prior CDK4/6 inhibitors. The safety profile was manageable, with common side effects including hyperglycemia, stomatitis, and rash. These results supported the initiation of the phase 3 VIKTORIA-2 trial.
Regulatory history
Gedatolisib has not received any expedited designations (e.g., fast track, breakthrough) from the FDA as of now. The VIKTORIA-2 trial is the pivotal phase 3 study that could support a New Drug Application (NDA) if successful.
Similar drug precedents
Similar drugs in this class include alpelisib (Piqray), which was approved for HR+/HER2- advanced breast cancer with PIK3CA mutations, but it is used in the second-line setting. Alpelisib showed a median PFS improvement of about 5.5 months over placebo in the SOLAR-1 trial. However, it has significant toxicities, including hyperglycemia and rash. Another precedent is the CDK4/6 inhibitors, which have become standard of care in the first-line setting, improving PFS by about 10 months over endocrine therapy alone. Gedatolisib aims to build on this by adding a PI3K/mTOR inhibitor to the CDK4/6 inhibitor backbone.