To Study the Effect of Inavolisib in Combination With Fulvestrant in Participants With Breast Cancer

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• Age18 Years to no maximum
• SexAll
• Healthy volunteersNo

You may be able to join if

• Documented ER +/ HER2- tumor according to American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines
• Disease progression after or during treatment with a combination of CDK4/6i and endocrine therapy: <= 1 prior lines of systemic therapy in the locally advanced (recurrent or progressed) or metastatic setting
• Measurable or evaluable disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1)
• Participants for whom endocrine-based therapy is recommended and treatment with cytotoxic chemotherapy is not indicated at time of entry into the study, as per national or local treatment guidelines
• Confirmation of biomarker eligibility: presence of >= 1 study-eligible PIK3CA mutation
• Life expectancy of > 6 months
• Ability, in the investigator's judgment, and willingness to comply with all study -related procedures, including completion of patient-reported outcomes

You cannot join if

• Metaplastic breast cancer
• Prior treatment with chemotherapy in the recurrent locally advanced/metastatic setting
• Type 2 diabetes requiring ongoing systemic treatment at the time of study entry; or any history of Type 1 diabetes
• Prior treatment with PI3K/Akt/mTOR inhibitors in the recurrent locally advanced/metastatic setting
• Requirement for daily supplemental oxygen
• Symptomatic active lung disease, including pneumonitis

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

inavolisib. An orally available inhibitor of phosphatidylinositol 3-kinase (PI3K), with potential antineoplastic activity. Upon administration, inavolisib binds to and inhibits various members of the PI3K family, including activating mutations in the catalytic alpha isoform PIK3CA. PI3K inhibition prevents the activation of the PI3K-mediated signaling pathway and results in the inhibition of growth and survival of PI3K-overexpressing tumor cells. Dysregulation of the PI3K signaling pathway is frequently associated with tumorigenesis and tumor resistance to a variety of antineoplastic agents and radiotherapy. PIK3CA, which encodes the p110-alpha catalytic subunit of the class I PI3K, is frequently mutated in a variety of cancer cell types and plays a key role in cancer cell growth and invasion. NCI Drug Dictionary

fulvestrant. A synthetic estrogen receptor antagonist. Unlike tamoxifen (which has partial agonist effects) and the aromatase inhibitors (which reduce the estrogen available to tumor cells), fulvestrant binds competitively to estrogen receptors in breast cancer cells, resulting in estrogen receptor deformation and decreased estrogen binding. In vitro studies indicate that fulvestrant reversibly inhibits the growth of tamoxifen-resistant, estrogen-sensitive, human breast cancer cell lines. NCI Drug Dictionary

Treatments listed in the registry

• Inavolisib (Drug): Participants will receive Inavolisib as per the schedule given in the protocol.
• Fulvestrant (Drug): Participants will receive Fulvestrant as per the schedule given in the protocol.

Randomized · Parallel · masking: None

Main goals

• Percentage of Participants With Objective Response Rate (ORR) (Up to approximately 2 years)
• Percentage of Participants With Treatment Emergent Adverse Events (TEAEs) (Up to approximately 2 years)

Other goals

• Duration of Response (DOR)
• Time to Response (TTR)
• Progression-free Survival (PFS)
• Percentage of Participants With Treatment Discontinuation due to Adverse Events
• Number of Participants Reporting Presence, Frequency, Severity and/or Degree of Interference With Daily Activities of Symptomatic Treatment Toxicities as Assessed by NCI Patient-Reported Outcomes Common Terminology Criteria for Adverse Events (PRO-CTCAE)
• Percentage of Participants Reporting Presence and Frequency of Selected Hyperglycemia Symptoms as Assessed by European Organisation for Research and Treatment of Cancer (EORTC) IL382
• Percentage of Participants Reporting Each Response Option at Each Time Point for the Treatment Side-Effect Bother Item General Population, Question 5 (GP5) From the Functional Assessment of Cancer Therapy - General (FACT-G) Questionnaire
• Change from Baseline in Symptomatic Treatment-Related Toxicities as Assessed Through use of the PRO-CTCAE
• Change from Baseline in Selected Hyperglycemia Symptoms as Assessed by EORTC IL382
• Change from Baseline in Treatment Side-effect Bother as Assessed Through use of the FACT-G GP5 Item

Planned enrollment: 80 (estimated).

• Los Angeles Cancer Network, Los Angeles, California
• Cancer Specialists of North Florida, Jacksonville, Florida
• HCA Midwest Division, Kansas City, Missouri
• Astera Cancer Care East Brunswick, East Brunswick, New Jersey

30 recruiting sites outside the US. Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT07368998
• NCI Drug Dictionary: C132166
• NCI Drug Dictionary: C1379

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Oct 5, 2026. Public record; not medical advice.