ASCO Daily News: Welcome to the ASCO Daily News Podcast. I'm Lauren Davis, and joining me today is Dr. Megan Cruz, a medical oncologist at the Cleveland Clinic who treats patients with breast cancer.

ASCO Daily News: Today we're talking about a new therapeutic option for patients with metastatic breast cancer who carry the PIC3CA mutation. Dr. Cruz, welcome to the podcast.

Dr. Megan Cruz: Good morning. Thank you for having me.

ASCO Daily News: We're glad you're here.

ASCO Daily News: So the PIK3CA is a commonly mutated gene in HR positive and HER2 negative advanced breast cancer. What kind of tests are used to detect this mutation?

Dr. Megan Cruz: Yes, so that's correct. The PI3 kinase mutation is found in about 40% of hormone receptor positive HER2 negative advanced breast cancer cases. And this mutation can actually be detected by a variety of tests, many of which are convenient for our patients.

Dr. Megan Cruz: Most commonly, we use tissue-based testing. And that can be samples of tissue that have been archived from either a patient's initial breast cancer diagnosis or a newer biopsy from a metastatic site. If neither of those places can be accessed or that tissue sample is no longer available, patients can have testing run on a blood-based sample. And this is often very helpful for patients who potentially have bone-only metastatic disease.

ASCO Daily News: Are new agents are available to treat this form of cancer?

Dr. Megan Cruz: Yes. So earlier this year, we had FDA approval of a new medication called alpelisib, which is used in combination with endocrine-based therapy in the form of fulvestrant in order to treat patients with the PI3 kinase mutated breast cancer.

ASCO Daily News: And how effective is this treatment in terms of survival or overall survival?

Dr. Megan Cruz: So this treatment was studied in the SOLAR-1 trial. And in that trial, it was found that there was a progression-free survival advantage for patients who received the combination of alpelisib and fulvestrant compared to placebo and fulvestrant. And that difference at 20 months was approximately from 11 months with alpelisib and fulvestrant from 5.7 months for the placebo fulvestrant combination.

ASCO Daily News: And what do clinicians need to know about side effects?

Dr. Megan Cruz: So there are some unique side effects with this medication, alpelisib, that clinicians will need to pay attention to. The most common ones are hypoglycemia and rash, which are generally pretty easily managed, but we have to be aware of them.

Dr. Megan Cruz: When starting a patient on this medication, they need to have fasting blood sugar testing as well as hemoglobin A1C testing done prior to starting as a baseline. And then shortly after initiation of the medication, we recheck these labs to make sure that they're staying stable.

Dr. Megan Cruz: If the blood sugar is rising, it's recommended to do more frequent monitoring and consideration of starting a medication like metformin to help control the blood sugars. In terms of the rash, that can actually be dealt with in a preventative way, where patients can be started on prophylactic antihistamine medications along with the start of alpelisib. And then if the rash does happen once they're on the medication, we often use either topical steroids or oral steroids to help control it.

Dr. Megan Cruz: The last toxicity that I think that the clinicians should be aware of his diarrhea, which is one that we're more familiar with managing from other chemotherapies and targeted agents. So typically, use of our common anti-diarrheal medications will help to control that.

ASCO Daily News: What do you think's on the horizon for metastatic breast cancer treatment?

Dr. Megan Cruz: I think that we will continue to see medications like this that are targeted for specific mutations that we find in a patient's breast cancer. And then along with that, I think we'll be combining these targeted medications potentially with immunotherapy moving forward. I think those are the new horizons for metastatic breast cancer treatment.

ASCO Daily News: Again, today my guest has been Dr. Megan Cruz. It's been a pleasure speaking with you. Thank you for being on our podcast.

Dr. Megan Cruz: Absolutely. Thanks for having me.

ASCO Daily News: And to our listeners, thank you for tuning into the ASCO Daily News Podcast. If you're enjoying the content, we encourage you to rate us and review us on Apple Podcast.

The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.