FDA Approves PI3K Inhibitors for Breast Cancer

The FDA has approved Piqray (alpelisib, Novartis) tablets, to be used in combination with FDA-approved endocrine therapy fulvestrant, to treat postmenopausal women and men with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, PIK3CA-mutated, advanced or metastatic breast cancer. 

The FDA also approved a companion diagnostic test, therascreenPIK3CA RWG PCR kit, to detect the PIK3CA mutation in a tissue or liquid biopsy. If a patient’s samples return a negative result from the test, they should also undergo a tumor biopsy for PIK3CA mutation testing. 

"Piqray is the first PI3K inhibitor to demonstrate a clinically meaningful benefit in treating patients with this type of breast cancer. 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," said Richard Pazdur, M.D., director of the FDA's Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research.

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Piqray’s efficacy was studied in a SOLAR-1 trial, randomized with 572 postmenopausal women and men with HR-positive, HER2-negative advanced or metastatic breast cancer whose cancer had progressed while taking, or after taking, an aromatase inhibitor. According to a press release, the results showed that the addition of Piqray to fulvestrant significantly prolonged the progression-free survival of patients whose tumors had a PIK3CA mutation. 

Common side effects of PIqray include high blood sugar levels, an increase in creatinine, diarrhea, rash, a decrease in lymphocyte count, elevated liver enzymes, nausea, fatigue, an increase in lipase, decreased appetite, stomatitis, vomiting, weight loss, low calcium levels, prolonged aPTT, and hair loss. 

Healthcare professionals should monitor patients for hypersensitivity reactions and are advised to not initiate treatment in patients with a history of severe skin reactions such as Stevens-Johnson syndrome, erythema multiforme, or toxic epidermal necrolysis. The safety of Piqray in patients with Type 1 or uncontrolled Type 2 diabetes has not been established at the time of this announcement. 

Prior to treatment initialization, healthcare professionals should check fasting glucose and HbA1c, and to optimize glycemic control. Throughout treatment, patients should be monitored for the development of pneumonitis/interstitial lung disease and diarrhea.