Considerations on the Use of GLP-1 Drugs in Breast Cancer Patients

In this MedPage Today video, Neil Iyengar, MD, of Memorial Sloan Kettering Cancer Center in New York City, examines the evidence and outstanding questions on the use of GLP-1 receptor agonists for breast cancer patients undergoing treatment and during survivorship.

The following is a transcript of his remarks:

We have very little data right now to answer the question of whether we should be using a GLP-1 or GLP agonist and incretin mimetic during or even after cancer therapy.

I will say that metabolic disorders like diabetes and cardiovascular disease are major problems for breast cancer survivors and breast cancer treatments can exacerbate metabolic disorders. We know that breast cancer survivors have more than a doubling in their risk of developing diabetes, and the No. 1 cause of death of women in the U.S. and essentially worldwide is cardiovascular disease. And patients that are diagnosed with breast cancer are at an elevated risk for cardiovascular disease. So I do currently recommend the use of weight-loss drugs if a patient meets the current indication once they’re in the survivorship setting. And we’ve seen some data that perhaps the hormone therapies, if they’re still on it, can reduce the amount of weight-loss from these drugs. So more data are needed.

I’m not currently recommending using the weight-loss drugs or starting them when a person has just been diagnosed with breast cancer or during chemotherapy, partly because we don’t have any safety data yet for those combinations. I suspect that the toxicity might compound, like nausea, for example. The weight-loss drugs, they slow gastric emptying, and we don’t know what that effect will be on oral chemotherapies or even oral hormone therapies, for example.

And we did see a small study reported here at San Antonio in 25 patients where the authors reported that in early-stage, triple-negative breast cancer treated with chemoimmunotherapy, the pCR [pathological complete response] rates were lower in patients who received the weight-loss drugs. But I caution folks on their interpretation of this data, because these patients had very advanced diabetes. They were on three, four, or more drugs for diabetes and the GLP agonists were added oftentimes as a fourth or fifth drug for diabetic control.

My interpretation of that data is not that it answers the question of whether we should be using these drugs during cancer therapy, but rather, patients who have aggressive diabetes that require multiple drugs for control and still don’t have adequate control are at unfortunately an increased risk for inadequate treatment response to breast cancer therapy.

There’s still a lot of unanswered questions right now, but I do think that the weight-loss drugs are likely to play an important role, at least in the survivorship setting.

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