Emerging Use of Weight Loss Drugs in Cancer Treatment
The demand for weight loss medications has surged recently, particularly for glucagon-like peptide 1 (GLP-1) agonists like semaglutide (Wegovy) and tirzepatide (Zepbound). Originally designed for obesity management, these drugs are also approved for treating type 2 diabetes and are gaining attention for their potential benefits, including reduced inflammation and depression.
Recent interest suggests that these antiobesity drugs could play a role in cancer care. Although data supporting the use of GLP-1 agonists for weight loss in cancer patients is limited, some oncologists are beginning to explore their application and study their effects.
Obesity can hinder the effectiveness of cancer treatments, particularly in breast cancer patients, and may increase the likelihood of treatment-related side effects. Managing weight could therefore enhance cancer outcomes, according to Dr. Lajos Pusztai, a breast cancer specialist at Yale School of Medicine.
While Dr. Pusztai's team hasn't yet adopted GLP-1 agonists in their practice, Dr. Neil Iyengar and his colleagues at Memorial Sloan Kettering Cancer Center have started to prescribe these medications to help breast cancer patients manage their weight. Dr. Iyengar estimates that nearly 40% of his patients are on these drugs, particularly those struggling with obesity.
How GLP-1s Work
GLP-1 is a hormone released by the small intestine after eating, and GLP-1 agonists mimic this hormone to promote insulin release and reduce glucagon production, both of which help regulate blood sugar levels. These medications also slow gastric emptying and increase feelings of fullness.
However, chemotherapy can cause nausea and vomiting, which is why Dr. Iyengar typically prescribes GLP-1 agonists during maintenance treatment rather than concurrently with chemotherapy.
Patients receive these medications through weekly self-administered subcutaneous injections, with oncologists referring them to endocrinologists or weight management specialists for prescriptions.
Dr. Emily Gallagher, an endocrinologist at Mount Sinai Hospital, has also prescribed GLP-1 drugs to several hundred cancer patients, particularly during maintenance hormone therapy for breast cancer. She has observed benefits in managing weight gain due to steroid use in multiple myeloma patients.
Limited Evidence
Despite promising potential, the evidence for GLP-1 agonists in cancer remains sparse and not yet mainstream. Current research primarily consists of small retrospective studies involving breast cancer patients on aromatase inhibitors. Initial findings indicate that weight loss in these patients is significantly lower compared to the general population.
In a study led by Dr. Iyengar, 75 women with breast cancer treated with GLP-1 agonists lost an average of 6.2 kg over 12 months, roughly 5% of their body weight. This is considerably less than the average weight loss observed in non-cancer patients, which is typically double that amount.
Further research has shown similar modest results, with a 4.34% reduction in body mass index (BMI) for patients taking Wegovy, compared to a 14% change in the general population. Some patients on Zepbound even experienced an overall increase in BMI.
It remains unclear why these drugs seem less effective for cancer patients. Hormonal therapies and metabolic changes from cancer treatments may interfere with weight loss, as these therapies can increase appetite and reduce metabolic rates, making weight management more challenging.
Safety Considerations
Both Wegovy and Zepbound carry warnings for potential thyroid C-cell tumors, although recent studies suggest they do not actually elevate the risk of thyroid cancer. These drugs are not recommended for individuals with a personal or family history of certain thyroid cancers or conditions like multiple endocrine neoplasia syndrome type 2.
Dr. Gallagher has not observed any secondary tumors in her cancer patients, while Dr. Iyengar cites larger datasets indicating no significant risks associated with these medications.
Concerns remain regarding the use of GLP-1 agonists in patients who have undergone bariatric surgery, as these drugs may exacerbate issues like slow gastric emptying.
Future Research and Potential
Manufacturers of GLP-1 medications are considering adding cancer treatment indications to their labels. Both Dr. Iyengar and Dr. Gallagher are in discussions to participate in large-scale, multicenter trials aimed at evaluating the effectiveness and safety of GLP-1 agonists in oncology.
Dr. Iyengar believes that if these drugs can demonstrate significant and lasting weight loss in cancer patients, it could mark a monumental advancement in treating obesity-related cancers. "This could be one of the biggest breakthroughs in medicine and oncology," he noted, especially given the increasing prevalence of obesity and its link to cancer.
Source: https://www.medscape.com/viewarticle/popular-weight-loss-drugs-now-patients-cancer-2024a1000hqy?form=fpf