Imagine a breakthrough in treating advanced breast cancer that's been stubbornly resisting standard therapies—could this be the game-changer we've been waiting for? Buckle up, because we're diving into the latest scoop on gedatolisib combined with fulvestrant, either alone or alongside palbociclib, as a promising new standard of care for hormone receptor-positive, HER2-negative, PIK3CA wild-type advanced breast cancer. And here's where it gets really intriguing: this approach shows benefits regardless of how long prior treatments kept the disease at bay, offering hope even for those who've battled it extensively. But don't just take our word for it—let's break it all down in a way that's easy to follow, even if you're new to the world of oncology.
Exciting updates from the phase 3 VIKTORIA-1 trial (NCT05501886) reveal that regimens incorporating gedatolisib plus fulvestrant, with or without palbociclib, delivered significant progression-free survival (PFS) advantages over fulvestrant alone in patients tackling this specific subtype of advanced breast cancer as a second-line option. For beginners, PFS is basically the measure of how long patients live without their cancer getting worse—think of it as a key indicator of treatment success. These findings, presented at the 2025 San Antonio Breast Cancer Symposium, held fascinating additional analyses focusing on PFS based on the time to progression (TTP) from the most recent therapy before this trial. TTP, in simple terms, tracks how quickly the cancer advanced after the last treatment, and these details help us understand if the therapy works better for some patients than others.
For instance, patients whose cancer took more than 6 months to progress on prior therapy saw impressive results with the gedatolisib triplet (gedatolisib plus palbociclib and fulvestrant): a median PFS of 9.9 months compared to just 1.9 months with fulvestrant alone, slashing the risk of progression by 80% (hazard ratio [HR], 0.20). The gedatolisib doublet (gedatolisib plus fulvestrant) wasn't far behind, with a median PFS of 7.6 months and a 75% risk reduction (HR, 0.25). If the prior treatment lasted over 12 months, the triplet extended PFS to 10.7 months versus 1.9 months with monotherapy (HR, 0.21), while the doublet hit 9.1 months (HR, 0.26). Even for those who held off progression for over 18 months, the triplet offered 12.4 months of PFS versus 1.9 months (HR, 0.17), and the doublet 10.0 months (HR, 0.19). Finally, in cases where progression was delayed beyond 24 months, the triplet achieved 12.4 months versus 2.0 months (HR, 0.26), and the doublet reached 13.6 months (HR, 0.14).
Barbara Pistilli, MD, head of the Breast Cancer Unit at Gustave Roussy in France, summed it up powerfully in her rapid-fire presentation: 'VIKTORIA-1 marks the first study to show a clear, meaningful PFS boost with PAM inhibition in PIK3CA wild-type cases, even after CDK4/6 inhibitors. These extra analyses reinforce gedatolisib's effectiveness, no matter the length of previous treatments.' For those unfamiliar, PAM inhibition targets pathways like PI3K, AKT, and mTOR that cancers often hijack to grow—think of it as blocking the cancer's fuel lines.
Now, let's zoom in on the trial's setup. VIKTORIA-1 evaluated gedatolisib in women with hormone receptor-positive, HER2-negative advanced breast cancer who'd progressed after CDK4/6 inhibitors and nonsteroidal aromatase inhibitors. To keep it relatable, aromatase inhibitors are drugs that lower estrogen levels, which fuel some breast cancers. Participants had up to two prior endocrine therapies for advanced disease, no history with mTOR, PI3K, or AKT inhibitors, or chemotherapy, and all were screened for PIK3CA mutations (wild-type means no mutations here). They were randomized evenly into three groups: the triplet (gedatolisib + palbociclib + fulvestrant), the doublet (gedatolisib + fulvestrant), or fulvestrant alone, with options to switch to combination treatments upon progression.
The drug dosing was straightforward: gedatolisib at 180 mg weekly in a 3-on/3-off cycle, palbociclib at 125 mg daily for 21 days followed by 7 off, and fulvestrant at 500 mg initially and then monthly. Stratification considered factors like lung or liver metastases and prior TTP to ensure fair comparisons. The main goals were PFS improvements in the combination arms over monotherapy, with secondary focuses on overall survival, response rates, safety, and quality of life.
To give you a quick overview of what this updated data reveals:
- Gedatolisib with fulvestrant, plus or minus palbociclib, boosted PFS compared to fulvestrant alone, regardless of prior treatment length in this breast cancer group.
- Benefits appeared in both bone-only and other metastases, with bigger wins in non-bone cases.
- Stomatitis (mouth sores) was the top side effect, but mostly mild and controllable.
- Time to noticeable quality-of-life decline was significantly pushed back with gedatolisib.
Earlier data from the 2025 ESMO Congress painted a similar picture: the triplet yielded 9.3 months median PFS versus 2.0 months (HR, 0.24), and the doublet 7.4 months (HR, 0.33). Preliminary survival stats suggested trends favoring combinations, though not yet conclusive. Response rates were 31.5% for the triplet, 28.3% for the doublet, and just 1% for monotherapy, with durable responses lasting over a year in combination groups.
Digging deeper into new efficacy insights from SABCS, PFS varied by metastasis type. For bone-only spread, combinations led to not-yet-reached median PFS versus 8.2 months with fulvestrant, though not statistically significant. But in non-bone cases, the triplet hit 9.3 months versus 1.9 months (HR, 0.23), and the doublet 7.3 months (HR, 0.32)—a stark contrast that underscores where the therapy shines most.
Safety-wise, stomatitis stole the spotlight, but Pistilli reassured that prophylactic steroid mouthwashes helped, and most cases were low-grade. About 69.2% in the triplet and 56.9% in the doublet experienced it, usually within the first three weeks, with grade 1 being most common. Recovery was quick: grade 2/3 events often subsided in 1-2 weeks. Hyperglycemia (high blood sugar) was minimal—no major issues, with stable glucose and HbA1c levels, and no dose cuts or stops due to it.
On patient-reported outcomes, using tools like EQ-5D-5L, quality of life held steady longer with gedatolisib: median time to deterioration was 23.7 months in the triplet versus 4 months with monotherapy (HR, 0.39), and not reached in the doublet (HR, 0.37). This means patients felt better for much longer, which is crucial for real-world treatment choices.
The big takeaway? As Pistilli concluded, 'This combo could become the new benchmark for managing HR-positive, HER2-negative, PIK3CA wild-type advanced breast cancer after CDK4/6 inhibitors.' And in November 2025, Celcuity filed a new drug application with the FDA for gedatolisib approval, backed by these VIKTORIA-1 results.
But here's where it gets controversial—while these results are promising, some might argue that the benefits in certain subgroups, like bone-only metastases, aren't as robust, raising questions about whether this should be a blanket standard or tailored further. Is pushing for a new therapy worth the potential side effects, or could we refine it even more? And this is the part most people miss: in an era of personalized medicine, how do we weigh broad PFS gains against individual patient experiences? We'd love to hear your thoughts—do you see this as a revolutionary step forward, or are there aspects that give you pause? Share your opinions in the comments below!
Disclosures: Pistilli received consulting fees from AstraZeneca, Seagen, Gilead, Novartis, Lilly, MSD, Pierre Fabre, Daiichi Sankyo, and Olema; research funding from AstraZeneca, Daiichi Sankyo, Gilead, Seagen, and MSD; and travel support from AstraZeneca, Gilead, MSD, Daiichi Sankyo, Accord, and Pfizer.
References
1. Pistilli B, Layman RM, Curigliano G, et al. Gedatolisib, a multitarget PI3K/AKT/mTOR inhibitor, plus fulvestrant with or without palbociclib for second-line treatment of patients with HR+/HER2-/PIK3CA-WT advanced breast cancer: updated results from the randomized, phase 3 VIKTORIA-1 trial. Presented at: 2025 San Antonio Breast Cancer Symposium; December 9-12, 2025; San Antonio, TX. Abstract R47-04.
2. Hurvitz SA, Layman RM, Curigliano G, et al. Gedatolisib plus fulvestrant, with and without palbociclib, vs fulvestrant in patients with HR+/HER2-/PIK3CA wild-type advanced breast cancer: first results from VIKTORIA-1. Presented at: 2025 ESMO Annual Congress; October 17-21, 2025; Berlin, Germany. Abstract LBA17.
3. Celcuity announces completion of submission of its new drug application to the US FDA for gedatolisib in HR+/HER2-/PIK3CA wild-type advanced breast cancer. News release. Celcuity, Inc. November 17, 2025. Accessed December 11, 2025. https://ir.celcuity.com/press-releases/
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