A Phase III, 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

Drug

Inavolisib

Participants will receive an inavolisib tablet to be taken orally (PO), once a day (QD), on Days 1-21 of each 21-day cycle, beginning on Day (D) 1 of Cycle (C) 1 of maintenance treatment.

Drug

Phesgo

Phesgo will be administered to participants subcutaneously every 3 weeks (Q3W) on D1 of each 21-day cycle.

Drug

Placebo

Inavolisib-matching tablet taken PO QD on Days 1-21 of each 21-day cycle, beginning on D1 C1 of maintenance treatment.

Drug

Taxane-based Chemotherapy

During the induction therapy phase, the investigator's choice of taxane-based chemotherapy will be administered after Phesgo.

Drug

Optional Endocrine Therapy of Investigator's Choice

Optional endocrine therapy (ET) is allowed at the discretion of the investigator, based on the standard of care. Allowed ETs are tamoxifen, or one of the specified third-generation aromatase inhibitor (AI \[anastrozole, letrozole, or exemestane\]), or fulvestrant. The investigator will determine and supply the appropriate luteinizing hormone-releasing hormone (LHRH) agonist locally approved for use in breast cancer. The LHRH agonist will be administered according to local prescribing information.

Summary

Eligibility

Interventions

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