Response of Brain Metastases From PIK3CA-Mutant Breast Cancer to Alpelisib.

Activating mutations of I PIK3CA i are found in 25%-40% of estrogen receptor-positive (ER+), HER2-negative (HER2-) breast cancers (BC), and in 8% of ER-negative (ER-) BC.[1] [5] Two recent studies support the benefit of PI3K inhibition in combination with endocrine therapy. Brain MRI 6 weeks later demonstrated a 14% reduction in the sum of longest distances of measurable brain metastases (24% reduction in bidimensional areas) and regressions of nonmeasurable brain metastases. A recent study showed that I PIK3CA i -mutant BC not only has a higher probability to metastasize to the brain than nonmutant BC (31% I v i 17%) but also has shorter median overall survival after the diagnosis of CNS metastasis (0.5 I v i 1.1 year).[9] The high frequency of brain metastases and their poor prognosis raise the question whether PI3K inhibitors can be beneficial for patients with active brain metastases. Breast Cancer Res; 13: R125, 2011 9 Fitzgerald DM, Muzikansky A, Pinto C, et al: Association between PIK3CA mutation status and development of brain metastases in HR+/HER2- metastatic breast cancer. [Extracted from the article]