San Antonio, Texas—Testing for mutations, such as PIK3CA, is uncommon among patients with hormone receptor (HR)-positive, HER2-negative, metastatic breast cancer, according to data being presented at the 2019 San Antonio Breast Cancer Symposium.

“The FDA approval for alpelisib after progression on endocrine therapy necessitates that PIK3CA status be ascertained relatively early in the course of disease of patients with HR-positive/HER2-negative metastatic breast cancer,” explained Nicole Princic, MS, IBM Watson Health, Cambridge, Massachusetts, and co-investigators, who sought to assess the prevalence and timepoint of mutation testing encompassing PIK3CA in postmenopausal members of this patient population.

Using the MarketScan Commercial and Medicare Supplemental Databases, Ms Princic et al retrospectively analyzed the claims data of 8499 patients with metastatic breast cancer (mean age, 66.5 years). The investigators specifically focused on postmenopausal women diagnosed between January 1, 2012, and July 31, 2018 (index date = first metastasis diagnosis date), with HR-positive/HER2-negative disease. Follow-up lasted from index until death, withdrawal, or study conclusion occurred.

A Current Procedural Terminology (CPT) code (81404, 81455, 81445) for polymerase chain reaction (PCR) or next-generation sequencing (NGS) was used to capture mutation testing.

Overall, patients were followed-up with for an average time frame of 1.9 years. During that period, 177 (2.1%) patients had NGS or PCR inclusive of the PIK3CA test. Approximately 30% (n = 51) of patients with a test underwent testing before receiving first-line therapy for metastatic disease, whereas 126 (71.2%) had testing done during or after first-line therapy

Furthermore, approximately 88% (n = 156) of patients paid a visit to their physician for breast cancer–related reasons within the 30 days before the test.

“Patients with HR-positive/HER2-negative metastatic breast cancer are infrequently tested for mutations such as PIK3CA, with majority of patients not being tested before the initiation of first line therapy. The demonstrated benefit of alpelisib in patients with PIK3CA mutations likely necessitates widespread testing for this important predictive factor early in the disease course,” Dr Princic and colleagues concluded.—Hina Porcelli

Princic N, Said Q, Smith D, et al. PIK3CA mutation testing prevalence among post-menopausal (PM) women with hormone receptor positive and human epidermal growth factor receptor 2 negative (HR+/HER2-) metastatic breast cancer (mBC) using real world data. Presented at: the 2019 San Antonio Breast Cancer Symposium; December 10-14, 2019; San Antonio, TX. Abstract P1-18-18.