Biomarker Testing and Alpelisib Treatment Patterns for Metastatic Breast Cancer in the Community Oncology Setting
A study presented at the 2021 San Antonio Breast Cancer Symposium assessed biomarker testing, treatment patterns, and patient characteristics for patients with metastatic breast cancer at Texas Oncology from 2015 to 2020, aiming to understand the real-world integration of alpelisib into clinical practice for this patient population.
The index date for the study was defined as the first date of a new diagnosis of advanced breast cancer between January 2015 and June 2020 with a minimum follow-up of 6 months. Treatment patterns were assessed until December 2020.
The electronic medical record and Texas Oncology Precision Medicine Molecular databases were used to mine for information including total number of patients with metastatic breast cancer, HR and HER2 status, and the presence and classification of PIK3CA mutations.
The study included 1093 patients with available information on PIK3CA, HR, HER2 status and systemic treatment. Of these patients, 768 (70%) were HR-positive/HER2-negative, 220 (20%) were HR-negative/HER2-negative, 73 (7%) were HR-positive/HER2-positive and 32 (3%) were HR-negative/HER2-positive. Among all subtypes, 410 (38%) were PIK3CA mutant, and within HR-positive/HER2-negative cohort, 333 (43%) were PIK3CA mutant.
Overall, 105 patients were treated with alpelisib. Of these patients, 102 (97%) were treated after FDA approval and 3 (3%) received alpelisib via compassionate use program.
Among patients with HR-positive/HER2-negative/PIK3CA mutant disease (n = 333), 97 (29%) were treated with alpelisib. The most frequent (n = 84, 87%) alpelisib-containing regimen is alpelisib plus fulvestrant, which was most often administered as second- (n = 28, 29%), third- (n = 16, 16%), and fourth-line (n = 16, 16%) of therapy.
Of the 97 patients with HR-positive/HER2-negative/PIK3CA mutant disease treated with alpelisib, 69 (71%) were treated previously with a cyclin-dependent kinase 4/6 inhibitor. The median duration of alpelisib therapy was 4.6 months.
As of December 30, 2020, 34 of the 97 patients had treatment with alpelisib ongoing, 24 expired, 14 were referred to hospice, 18 completed last recorded line of therapy prior to study end date, and 7 patients progressed to the next line of therapy.
No significant difference was reported between patients treated vs not treated with alpelisib regarding patient age or performance status. The most common PIK3CA mutations were H1047R, E545K, E542K, N345K and H1047L, and 43 (10%) had ≥2 mutations.
O'Shaughnessy J, Paulson S, Brisbin L, et al. A real-world assessment of PIK3CA testing and alpelisib treatment patterns among metastatic breast cancer patients in a community oncology setting. Presented at: 2021 San Antonio Breast Cancer Symposium; December 7-10, 2021; virtual. Abstract P5-13-16.
