Study of the Molecular Features of Postmenopausal Women With HR+ HER2-negative aBC on First-line Treatment With Ribociclib and Letrozole and, in Patients With a PIK3CA Mutation, on Second-line Treatment With Alpelisib Plus Fulvestrant

Inclusion Criteria

• •Patient has an advanced (locoregionally recurrent or metastatic) breast cancer in first line treatment (treatment naïve for the advanced setting).
• •Patient is in post-menopause, defined by one of the following:
• •Prior bilateral oophorectomy
• •Age ≥60
• •Age \<60 and amenorrhea for 12 or more months (in the absence of chemotherapy, tamoxifen, toremifen, or ovarian suppression) and FSH and estradiol in the postmenopausal range per local normal range
• •Patient has a histologically and/or cytologically confirmed diagnosis of estrogenreceptor positive and/or progesterone receptor positive breast cancer by local laboratory.
• •Patient has an HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (FISH, CISH, or SISH) test is required by local laboratory testing.
• •Patient is willing to undergo blood and tumor sample collection for the biological assessments/objectives as scheduled in the protocol.
• •Patient has been discontinued (any reason allowed) from treatment with ribociclib + letrozole in the core phase and is deemed suitable for treatment with alpelisib + fulvestrant in second line. Ribociclib + letrozole must be the last treatment regimen before alpelisib + fulvestrant.
• •Patient has PIK3CA mutation as determined in tumor tissue and/or plasma by a Novartis designated laboratory. Results of tissue samples obtained during the core phase (screening or EOT) are acceptable