Dr Dillon on Considerations for GLP-1s in the Neuroendocrine Tumor Space

In recent years, the clinical use of glucagon-like peptide-1 (GLP-1) receptor agonists, initially indicated for diabetes and obesity management, has rapidly expanded, with many ongoing investigations into their therapeutic use across a wide range of noncommunicable diseases.¹ At the 2025 North American Neuroendocrine Tumor Society (NANETS) Multidisciplinary NET Medical Symposium, Joseph Dillon, MB, BCh, BAO, discussed the integration of GLP-1 agents into patient care, highlighting theoretical risks and potential safety considerations in different groups of patients, including those with complex endocrine syndromes like MEN1.²

In an interview, Dillon, professor of internal medicine (endocrinology and metabolism) at Carver College of Medicine at the University of Iowa, talked to Targeted Oncology® about considerations and potential risks of GLP-1 agents when used in patients with neuroendocrine tumors (NETs) based on current preclinical evidence, as well as current knowledge gaps that warrant future clinical investigation.

Targeted Oncology: How has the rise of GLP-1 medications impacted NET patient care?

Joseph Dillon, MD: These are very important drugs that have been approved for diabetes, obesity, and related conditions. They have a huge market share at this time, and approximately 6% of our patients within a NET clinic are taking these agents, just as 6% of the adult population in the United States is taking these agents. Up to now, we don't know, or there haven’t been specific reports of direct impacts on patients with NETs, but there are some theoretical suggestions that these agents could have impact on some [of these] patients.

What are some considerations clinicians should have with GLP-1 medications regarding patients with NETs?

Patients take these agents for diabetes, obesity, and related concerns. Many of our patients with [NETs] will have diabetes and obesity as well, given that 15% of the adult population has type 2 diabetes in the United States, and 40% of the adult population has obesity. The concern is that [in] a proportion of patients with [NETs], those [NETs] have receptors for the GLP-like molecules. In studies in animals and in vitro, we find that if tumors have receptors for GLP and there's GLP added to those tumors, those tumors will grow. Whether that translates into the human experience is unclear, but there's a potential for growth in a proportion of patients with [NETs]; there's a potential for growth of those [NETs] when given GLP and related agents.

What unanswered questions do you have about GLP-1s in the NET space?

I think the unanswered question is, first of all, which patients’ [NETs] do have the GLP receptor expressed on them? That is, which patients will be at potential risk for use of GLP agents? And then, we need to know at a human level, rather than at a mouse level or test tube level, whether GLP and related agents have a significant effect on the growth of these tumors.

REFERENCES:

1. Moiz A, Filion KB, Tsoukas MA, et al. The expanding role of GLP-1 receptor agonists: a narrative review of current evidence and future directions. EClinicalMedicine. 2025;86:103363. doi:10.1016/j.eclinm.2025.103363

2. Dillon, J. Clinical integration of GLP-1 into patient care - risks and clinical integration (MEN1, diabetes, syndromic patients, etc.). Presented at: 2025 NANETS Multidisciplinary NET Medical Symposium; October 23-25, 2025; Austin, TX.