Breast cancer drugs may weaken the effects of weight-loss drugs

CHICAGO — Anti-obesity drugs may not work as well for women taking certain breast cancer drugs, researchers report here.

Among 99 breast cancer survivors taking aromatase inhibitors (AIs), weight loss after one year of taking anti-obesity drugs was less than 10%, according to Sima Fansa, M.D., of the Mayo Clinic in Rochester, Minnesota. It was 42% lower than women not taking AIs.

At 12 months, women who were not taking antiobesity drugs lost 9.1% of their total weight on antiobesity drugs, while women who took both drugs lost 5.3%, she explained. Endo 2023Annual Meeting of the Endocrine Society.

Differences in total weight loss were apparent as early as 3 months after taking anti-obesity medications and persisted throughout the year.

Women taking AIs were less likely to achieve significant weight loss after taking anti-obesity drugs for 1 year than women not taking anti-obesity drugs.

• At least 5% of body weight: 49% of women using AI vs. 72% of women not using AI
• At least 10% of body weight: 22% vs 48%
• At least 15% of body weight: 5% vs. 21%

“Up to 27% of women taking aromatase inhibitors to treat breast cancer gain weight,” Dr. Fansa noted at a press conference, prompting clinicians to warn patients about this potential side effect. added that it should. Cardiovascular disease is the most common cause of non-cancer death among breast cancer survivors, she added, and obesity only increases this risk.

“Despite breast cancer survivors reporting greater weight concerns after breast cancer diagnosis, there are significant gaps in the provision of advice and guidelines on weight gain prevention and weight management.” she added.

Several significant alterations in metabolic parameters were found in breast cancer survivors using AI. For example, after her one year of taking anti-obesity drugs, her fasting blood glucose level decreased by an average of 33.9 mg/dL, her HbA1c decreased by 1.1%, and her LDL cholesterol decreased by 15.6 mmol/L. However, women not taking AIs had metabolic benefits that went beyond all three of these measures, as well as improvements in blood pressure and non-HDL cholesterol.

Fansa’s group identified several factors that predicted increased weight loss in breast cancer survivors with these agents. While taking anti-obesity medications, those with higher doses of weight-loss medications and behavioral therapy tended to lose more weight, but not with type 2 diabetes.

Most of the women who participated in the multicenter retrospective study Semaglutide (Wegovy) use AI, compared to 74.2% who do not. Those not taking semaglutide were taking liraglutide (Saxenda) (19.1% vs. 9.7%, respectively) or phentermine (11.1% vs. 16.1%, respectively).

“In fact, semaglutide was the best of the three [at inducing weight loss in this population]said Fansa Today’s Medpage. “We hope that future studies will include all FDA-approved drugs to provide a more comprehensive view.”

Fans also said,[s]Studies are needed to assess the mechanisms behind different weight loss responses. [anti-obesity medications] We hypothesize that the proportion of women taking AIs may be related to the anti-estrogenic effects of AIs on lean mass and fat mass. ”

“The more drugs available, the better.” [for these patients] Because we can offer patients more options so that they can choose what is best for them in terms of side effects, mechanism of action and drug intake,” she added when speaking about expectations. Approval of new anti-obesity drugs on the horizon.

The women in the study had an average age of 63 years, were nearly all white, and had an average baseline BMI of 34.5.