Alpelisib (Piqray) is a targeted therapy approved by the U.S. Food and Drug Administration to treat people with advanced or metastatic, hormone receptor-positive breast cancer that has tested positive for a mutation on the PIK3CA gene. It is a PI3K (phosphatidylinositol-3 kinase) inhibitor, a type of medicine that works by blocking a pathway in cancer cells, called PI3K, that may cause breast cancers to stop responding to hormonal therapies. It is given with the hormonal therapy fulvestrant (Faslodex).

Alpelisib was approved by the FDA in May 2019 and is the first PI3K inhibitor approved to treat breast cancer.

How alpelisib works

A mutation on the PIK3CA gene can cause the PI3K pathway in breast cancer cells to become too active. Researchers believe this path causes some breast cancer to stop responding to hormonal therapy. Alpelisib is a PI3K inhibitor, meaning it blocks this pathway and works with hormonal therapy to keep the cancer from growing.

Who gets alpelisib

Alpelisib is approved for people with advanced or metastatic, hormone receptor-positive, HER2-negative breast cancer that has grown during or after treatment with hormonal therapy. The tumor must also test positive for a mutation on the PIK3CA gene. This mutation is present in the tumors of about 40 percent of people with this diagnosis. Along with alpelisib, the FDA approved a biomarker test, the therascreenPIK3CA RGQ PCR kit, to test for this mutation.

How alpelisib is given

Alpelisib is a pill. The standard dose is two 150 milligram tablets each day. It is given along with fulvestrant, which is given as a shot. Fulvestrant is given three times the first month, then once a month after that.

Side effects and things to remember

High blood sugar is a notable side effect of alpelisib. In the SOLAR-1 trial it was the most common reason people stopped treatment with alpelisib. It can be managed with diabetes medicines, changes in diet, changes to the dose of alpelisib, and taking a break from alpelisib.

Other common side effects were

Tell your doctor if you are pregnant or planning to become pregnant. Alpelisib may be dangerous to a fetus so it is recommended that you not take this medicine while pregnant and not get pregnant for at least a week after you have stopped treatment.

Alpelisib can also cause some serious but rare conditions including lung inflammation, allergic reactions, and severe skin reactions. Let your doctor know if you have had any serious skin reactions to medicines in the past.



Reviewed and updated: August 16, 2019

Reviewed by: Adam Brufsky, MD, PhD


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