FDA Approves Gedatolisib for Some HR-Positive, HER2-Negative Breast Cancers

The approval, in its exact words

On July 14, 2026, FDA approved gedatolisib, sold as Revtorpyk. It is given with fulvestrant, with or without palbociclib.

The approved group is narrow, and every clause matters. Adults with hormone receptor positive, HER2-negative breast cancer that is locally advanced or metastatic. With no PIK3CA mutation detected. After the disease progressed on or after at least one line of endocrine therapy given in the metastatic setting.

Read that again if it helps. The absence of a mutation is part of the eligibility, which is unusual and easy to misread.

What the tumor labels mean

Hormone receptor positive means the cancer cells carry receptors for estrogen, progesterone, or both. Estrogen acts on those receptors like fuel. So the first line of treatment is endocrine therapy, which either lowers estrogen or blocks the receptor.

HER2-negative means the cells do not overproduce the HER2 protein, so the drugs aimed at HER2 do not apply.

Our pages on hormone receptor status and HER2 status explain how those results are reported.

The pathway this drug blocks

Inside the cell there is a signaling chain often called the PI3K pathway. PI3K passes a signal to AKT, which passes it to mTOR, and the end result is a cell that grows and resists dying.

Breast cancers frequently escape endocrine therapy by turning that chain up. Sometimes the cause is a mutation in the PIK3CA gene, and there are already drugs approved for that situation.

This approval covers the other group: the cancers with no PIK3CA mutation found, which have had fewer targeted options. Gedatolisib blocks the pathway at more than one point rather than only at the mutated protein.

Fulvestrant is its partner here. It is an endocrine drug that degrades the estrogen receptor rather than merely blocking it. Palbociclib is optional in the approved regimen and belongs to a different class again. Our page on CDK4/6 inhibitors explains what those do.

What VIKTORIA-1 measured

The evidence is Study 1 of VIKTORIA-1, registry number NCT05501886. The registry lists it as a phase 3 trial. FDA reports that Study 1 enrolled 392 adults.

Participants were randomly assigned in equal numbers to three arms. Arm A received gedatolisib, fulvestrant and palbociclib. Arm B received gedatolisib and fulvestrant. Arm C received fulvestrant alone.

The main measure was progression-free survival, judged by reviewers who did not know which arm a scan came from. Progression-free survival is the time until the cancer grows again or the person dies.

The results were as follows. Arm A reached a median of 9.3 months against 2.0 months for fulvestrant alone, with a hazard ratio of 0.24. Arm B reached 7.4 months against the same 2.0 months, with a hazard ratio of 0.33. Both comparisons had p-values below 0.0001.

Response rates in people with measurable disease were 32 percent in Arm A and 28 percent in Arm B, against 1 percent in Arm C. Median duration of response was 17.5 months in Arm A and 12.0 months in Arm B.

The number that has not arrived

FDA states it plainly. At the time of the progression-free survival analysis, overall survival data were not mature. Only 25 percent of the overall population had died.

That matters more than it sounds. A treatment can delay tumor growth on a scan without changing how long someone lives. Until the survival analysis matures, that question is genuinely open.

Note also that the control arm was fulvestrant on its own. That is a modest comparator, which is part of why the difference looks so large.

Dose and what to watch for

The recommended dose is 180 mg by intravenous infusion over 30 minutes, once a week on days 1, 8 and 15 of every 28-day cycle. It continues until the cancer grows or the side effects become unacceptable.

FDA lists warnings and precautions for four things: stomatitis, dermatologic reactions, hyperglycemia, and harm to a developing fetus.

Those translate as follows, and each has a practical threshold worth agreeing with the team.

• Stomatitis means mouth sores. Report them when eating or drinking becomes difficult, not after you have stopped eating.
• Skin reactions: report a new rash early, and urgently if it blisters, peels, or involves the mouth or eyes.
• Hyperglycemia means high blood sugar. Ask whether your glucose will be checked before treatment and during it. Increased thirst, frequent urination, and blurred vision are the symptoms to report.
• Effective contraception is advised because of the risk to a fetus.

What this does not mean

• The approval requires no PIK3CA mutation to have been found. It does not apply to everyone with HR-positive, HER2-negative breast cancer.
• Progression-free survival improved substantially. Overall survival was not mature at the analysis, so a survival benefit is not established.
• The comparison was against fulvestrant alone, not against every treatment a person might otherwise receive.
• A median is a midpoint. Half the people in an arm did better than the figure and half did worse.
• SEER, the federal cancer surveillance program, records five-year relative survival of 33.8 percent for breast cancer that has reached distant sites. That is a group average from people diagnosed years ago, it predates this drug entirely, and it does not describe any individual.
• Where this fits in a treatment sequence is a clinical decision that depends on prior therapy and on the tumor's own report.

Sources

• FDA: FDA approves gedatolisib with fulvestrant, with or without palbociclib
• ClinicalTrials.gov API v2 record for NCT05501886 (VIKTORIA-1)
• DailyMed: REVTORPYK (gedatolisib) prescribing information (SPL)
• NCI PDQ: Breast Cancer Treatment (Health Professional Version)
• NCI SEER Cancer Stat Facts: Female Breast Cancer

How this article was prepared

An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.

Cancer Explained is published by the National Cancer Information Foundation. It is not medical advice and does not suggest a test or treatment.

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