Could GLP-1 Drugs Potentially Help Treat Cancer? 1 Promising Study Suggests They Might

A recent study presented at the Endocrine Society's annual meeting revealed that Eli Lilly's GLP-1 agonist, tirzepatide, caused tumor shrinkage in mice, indicating a potential future therapeutic application in oncology. While this finding is preliminary and regulatory approval for cancer treatment would require years of human trials, it suggests a massive new sales growth opportunity for Eli Lilly, whose GLP-1 drugs already drive significant revenue, with sales up 45% year-over-year in Q1 2025.

Analysis

A recent preclinical study has revealed a potential new therapeutic avenue for Eli Lilly's (LLY) GLP-1 agonist, tirzepatide, beyond its established success in diabetes and weight loss. The study, conducted on 16 mice, demonstrated that administration of tirzepatide resulted in an approximate 20% reduction in tumor volume, which correlated with a similar percentage of weight loss over a 16-week period. While this finding suggests a massive potential expansion into the oncology market, it is critical to note that the data is preliminary and years of human trials would be required for any regulatory label expansion. This potential catalyst is layered on top of an already robust growth story for Eli Lilly, which saw its Q1 2025 revenue surge 45% year-over-year to $12.7 billion, with its GLP-1 drugs Mounjaro and Zepbound contributing $6.2 billion to that total. The company's stock currently trades at a premium, with a trailing P/E multiple of 65, however, its 5-year price-to-earnings growth (PEG) ratio of 1.2 suggests this valuation may be justified by its medium-term growth trajectory.

Key Decisions for Investors

• Investors should view the preliminary oncology findings as a long-duration call option on a significant new market for tirzepatide, while recognizing that any material impact is years away and dependent on successful human trials.
• The current valuation, reflected by a 65x trailing P/E, must be weighed against strong forward-looking growth, for which the 1.2 PEG ratio provides some justification for long-term investors.
• Monitor for any further clinical data or company announcements regarding new indications for tirzepatide, as the expansion of its approved uses beyond diabetes and weight loss is the central pillar of the long-term bullish thesis.
• Given the stock is up a modest 4% this year, the current price could be considered a potential entry point for long-term investors who believe in the expanding pipeline, despite the currently high valuation multiples.