Postmenopausal women and men with advanced-stage hormone-receptor-positive, HER2-negative breast cancer with a PIK3CA mutation that grew during or after hormonal therapy lived about 8 months longer when treated with the combination of Piqray (chemical name: alpelisib) and Faslodex (chemical name: fulvestrant) compared to Faslodex alone.
These latest results from the SOLAR-1 study were presented on Sept. 19, 2020, at the European Society for Medical Oncology Virtual Congress 2020. Read the abstract of “Overall survival (os) results from SOLAR-1, a phase III study of alpelisib (ALP) + fulvestrant (FUL) for hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) advanced breast cancer (ABC).”
Advanced-stage breast cancer is breast cancer that has spread to tissue near the breast (locally advanced) or to parts of the body away from the breast, such as the bones or liver (metastatic).
Overall survival is how long a person lives, whether or not the cancer grows.
About Piqray and Faslodex
Piqray is a targeted therapy medicine that inhibits the PI3K pathway. The PI3K pathway helps all cells — both healthy and cancer cells — get the energy they need. When this pathway is overactivated because of a mutation in the PIK3CA gene, it can allow cancer cells to survive and grow. PI3K inhibitors block this pathway, with the goal of killing cancer cells.
In hormone-receptor-positive breast cancers, a PIK3CA mutation also can make the cancer resistant to hormonal therapy medicines.
About 40% of people diagnosed with hormone-receptor-positive, HER2-negative breast cancer have a PIK3CA mutation.
Piqray is a pill taken by mouth.
Faslodex is a hormonal therapy medicine called an estrogen receptor downregulator. Faslodex sits in the estrogen receptor in breast cells so the cell can’t receive estrogen’s signals to grow and multiply. Faslodex also reduces the number of estrogen receptors and changes the shape of breast cell estrogen receptors so they don’t work as well. Faslodex is a liquid that is given once a month as an injection into a muscle.
The SOLAR-1 trial
The SOLAR-1 trial included 572 people diagnosed with advanced-stage hormone-receptor-positive, HER2-negative breast cancer that had previously been treated with hormonal therapy; 341 of the cancers had a PIK3CA mutation. The people in the study were either postmenopausal women or men.
The people were randomly split into two treatment groups:
- Piqray plus Faslodex
- placebo (a pill that looked just like Piqray, but contained no medicine) plus Faslodex
Median follow-up time was 30.8 months. This means that researchers tracked half the people for a longer time and half the people for a shorter time.
For the 341 people diagnosed with cancer with a PIK3CA mutation, overall survival was:
- 39.3 months for people treated with Piqray and Faslodex
- 31.4 months for people treated with Faslodex alone
This difference of about 8 months was not statistically significant, which means that it could have been due to chance and not because of the difference in treatment.
Still, the researchers who did the study said the difference in overall survival was clinically meaningful and supports using Piqray to treat advanced-stage hormone-receptor-positive, HER2-negative breast cancer with a PIK3CA mutation that has grown after hormonal therapy.
Piqray side effects
Like almost all cancer medicines, Piqray can cause side effects, some of them severe.
The most common side effects of Piqray are:
- high blood sugar levels
- high creatinine levels, which can mean kidney problems
- low white blood cell counts
- mouth sores
- hair loss
- loss of appetite
Piqray also may cause serious side effects, including:
- Severe skin reactions: In some people, Piqray may cause Stevens-Johnson syndrome or erythema multiforme, skin disorders that may begin with flu-like symptoms followed by a painful rash that blisters. If you have a history of either of these two conditions or other skin disorders, discuss them with your doctor before you start treatment with Piqray.
- High blood sugar: The safety of Piqray has not been established in people diagnosed with Type 1 or uncontrolled Type 2 diabetes. If you have diabetes, your doctor will measure your fasting blood sugar levels and will monitor these levels while you’re being treated with Piqray. If you have symptoms of untreated high blood sugar, including frequent urination, blurred vision, or an increase in thirst, tell your doctor immediately.
- Pneumonia: Piqray may make some people more likely to develop pneumonia or other upper respiratory infections. Tell your doctor right away if you have chest pain when you breathe or cough, or if you have a fever or chills.
- Diarrhea: While moderate diarrhea is a common side effect of Piqray, the medicine also can cause severe diarrhea, which can lead to dehydration and may cause kidney problems. Your doctor will recommend an antidiarrheal medicine while you’re being treated with Piqray. If you have diarrhea, tell your doctor immediately.
What this means for you
If you’re a postmenopausal woman or a man who has been diagnosed with advanced-stage hormone-receptor-positive, HER2-negative breast cancer with a PIK3CA mutation that has grown after treatment with hormonal therapy, the latest results from the SOLAR-1 study are very encouraging.
Earlier results from the SOLAR-1 trial showed that Piqray and Faslodex led to longer progression-free survival compared to Faslodex alone. Progression-free survival is how long a person lives without the cancer growing.
These latest results showing 8 months longer overall survival for people treated with Piqray and Faslodex, while not statistically significant, offer more support for using Piqray to treat this type of breast cancer.
If you’re being treated for advanced-stage hormone-receptor-positive, HER2-negative breast cancer with a PIK3CA mutation that has stopped responding to the first hormonal therapy, you and your doctor are likely considering several treatment options, including Piqray. Together, you will weigh the benefits and risks of each treatment and decide on the best treatment plan for your unique situation.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser
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