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A phase 3, multicenter, randomized, double-blind, placebo-controlled study evaluating the efficacy and safety of inavolisib in combination with phesgo versus placebo in combination with phesgo as maintenance therapy after first line induction therapy in participants with PIK3CA-mutated HER2-positive locally advanced or metastatic breast cancer

A Study to Evaluate the Efficacy and Safety of Inavolisib in Combination With Phesgo Versus Placebo in Combination With Phesgo in Participants With PIK3CA-Mutated HER2-Positive Locally Advanced or Metastatic Breast Cancer

Fabiola Amair-Pinedo

F. Hoffmann-La Roche

1-1 NIHONBASHI-MUROMACHI 2-CHOME, CHUO-KU,Tokyo

clinical-trials@chugai-pharm.co.jp

Clinical trials information

Chugai Pharmaceutical Co., Ltd.

1-1 NIHONBASHI-MUROMACHI 2-CHOME, CHUO-KU,Tokyo

+81-120189706

clinical-trials@chugai-pharm.co.jp

Recruiting

Jan. 16, 2026

Interventional

randomized controlled trial

double blind

placebo control

parallel assignment

treatment purpose

-Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1
-Histologically or cytologically confirmed and documented adenocarcinoma of the breast with metastatic or locally advanced disease not amenable to curative resection
-Confirmation of HER2 biomarker eligibility based on valid results from central testing of tumor tissue documenting HER2-positivity
-Confirmation of PIK3CA-mutation biomarker eligibility based on valid results from central testing of tumor tissue documenting PIK3CA-mutated tumor status
-Disease-free interval from completion of adjuvant or neoadjuvant systemic non-hormonal treatment to recurrence of >= 6 months
-LVEF (left ventricular ejection fraction) of at least 50% measured by echocardiogram (ECHO) or multiple-gated acquisition scan (MUGA)
-Adequate hematologic and organ function prior to initiation of study treatment

-Prior treatment in the locally advanced or metastatic setting with any PI3K, AKT, or mTOR inhibitor or any agent whose mechanism of action is to inhibit the PI3K-AKT-mTOR pathway
-Any prior systemic non-hormonal anti-cancer therapy for locally advanced or metastatic HER2-positive breast cancer prior to initiation of induction therapy
-History or active inflammatory bowel disease
-Disease progression within 6 months of receiving any HER2-targeted therapy
-Type 2 diabetes requiring ongoing systemic treatment at the time of study entry; or any history of Type 1 diabetes
-Participants with active HBV infection
-Clinically significant and active liver disease, including severe liver impairment, viral or other hepatitis, current alcohol abuse, or cirrhosis
-Symptomatic active lung disease, including pneumonitis or interstitial lung disease
-Any history of leptomeningeal disease or carcinomatous meningitis
-Serious infection requiring IV antibiotics within 7 days prior to Day 1 of Cycle 1
-Any concurrent ocular or intraocular condition that, in the opinion of the investigator, would require medical or surgical intervention during the study period to prevent or treat vision loss that might result from that condition
-Active inflammatory or infectious conditions in either eye or history of idiopathic or autoimmune-associated uveitis in either eye

Both

PIK3CA-mutated HER2-positive locally advanced or metastatic breast cancer

Inavolisib: Inavolisib will be administered orally 9mg QD.
Placebo: Placebo will be administered orally QD.
Pertuzumab(Genetical Recombination), Trastuzumab(Genetical Recombination), Vorhyaluronidase Alfa(Genetical Recombination): Administer the standard dose by intravenous injection.
Docetaxel Hydrate: Administer the standard dose by intravenous injection.
Paclitaxel: Administer the standard dose by intravenous injection.

efficacy
Investigator-Assessed Progression-Free Survival (PFS)

safety, efficacy, phamacokinetics
"Overall Survival (OS)
Investigator-Assessed Objective Response Rate (ORR)
Investigator-Assessed Duration of Response (DOR)
Investigator-Assessed Clinical Benefit Rate (CBR)
Investigator-Assessed PFS2
Mean and Mean Changes from Baseline Score in Function and Health-Related Quality of Life (HRQoL)
Percentage of Participants with Adverse Events
Plasma Concentration of Inavolisib at Specified Timepoints

+81-43-264-5431

Nov. 12, 2025

Yes

Qualified researchers may request access to individual patient level data through the clinical study data request platform. For further details on Chugai's Data Sharing Policy and how to request access to related clinical study documents, see here (www.chugai-pharm.co.jp/english/profile/rd/ctds_request.html).

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