News From the Food and Drug Administration
July 2, 2019
First PI3K Inhibitor for Breast Cancer
JAMA. 2019;322(1):19. doi:10.1001/jama.2019.8916
Alpelisib has received FDA
approval for postmenopausal women, and men, with advanced or metastatic breast cancer whose tumors have a mutation in the
PIK3CA gene. The drug is indicated for use in combination with the antiestrogen medication fulvestrant to treat hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (
ERBB2)–negative tumors after endocrine-based therapy.
A companion diagnostic test to detect the
PIK3CA mutation in a tissue sample and/or a liquid biopsy also received approval. Patients whose results are negative from the liquid biopsy test should undergo a tumor biopsy for
PIK3CA mutation testing, according to the FDA.
“The ability to target treatment to a patient’s specific genetic mutation or biomarker is becoming increasingly common in cancer treatment, and companion diagnostic tests assist oncologists in selecting patients who may benefit from these targeted treatments,” Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence, said in a statement.
The
PIK3CA gene encodes p110α, a catalytic subunit of phosphatidylinositol 3-kinase (PI3K), which is involved in cell growth and division. Alpelisib selectively inhibits p110α. In a clinical
trial, 572 patients with advanced HR-positive,
ERBB2-negative breast cancer that had progressed during or after aromatase inhibitor therapy were enrolled into either of 2 cohorts depending on their tumor mutation status (341 patients had confirmed
PIK3CA mutations). Within each cohort, patients were randomized to receive alpelisib or placebo plus fulvestrant.
After a median treatment time of 20 weeks, progression-free survival among patients with
PIK3CA mutations who received alpelisib and fulvestrant was 11 months compared with 5.7 months among those who received fulvestrant and placebo. Among patients without
PIK3CA mutations, progression-free survival was 7.4 months in the alpelisib-fulvestrant group and 5.6 months in the placebo-fulvestrant group.
After 12 months, progression-free survival among patients with
PIK3CA-mutated cancer was 46.3% in the alpelisib-fulvestrant group compared with 32.9% in the placebo-fulvestrant group. Among those without the mutation, progression-free survival at 12 months was 28.4% in the alpelisib-fulvestrant group and 22.2% in the placebo-fulvestrant group.
The most frequent adverse effects in the trial were hyperglycemia, diarrhea, nausea, decreased appetite, rash, and vomiting.