Eli Lilly weight-loss drug shows extraordinary promise

Eli Lilly & Co. has jumped to the lead in developing effective weight-loss medication.

Driving the news: Patients who took Lilly's experimental drug retatrutide lost 24% of their body weight, or an average of 58 pounds, after 48 weeks, according to results of a phase 2 clinical trial published in the New England Journal of Medicine and funded by the Indianapolis-based drugmaker.

Why it matters: The substantial, sustained weight loss observed in the study fuels optimism that medication can combat obesity, a condition that affects more than 40% of Americans — 47% in Indiana — and is associated with leading causes of death, including diabetes, heart disease and stroke.

Details: 338 trial patients received weekly injections of retatrutide, which "helps regulate blood sugar, slow stomach emptying and decrease appetite," per Reuters.

• The trial showed higher doses of the drug led to more weight loss — and participants continued to lose weight at the 48-week mark, suggesting a longer trial could yield further progress.
• Patients who took the placebo lost 2% of their body weight.

What they're saying: "This is an unusually high magnitude of efficacy as compared with findings in clinical trials of other antiobesity agents," Ania M. Jastreboff of the Yale University School of Medicine, wrote in the New England Journal of Medicine.

Yes, but: Higher doses of retatrutide came with stronger side effects, including nausea, diarrhea, vomiting and constipation.

• Plus: Because they are injectable, these treatments are harder for doctors to prescribe and patients to adhere to.

The big picture: Retatrutide blows away other weight-loss drugs so far, CNBC reports.

• Two Novo Nordisk drugs, Ozempic and Wegovy, have shown up to 15% weight loss in trials.
• Another Eli Lilly drug, Mounjaro, has helped patients lose up to 21% of their weight in trials, but so far it has been cleared to treat Type 2 diabetes — not as a weight loss drug.

What's next: Lilly is planning a phase 3 trial and hopes to mitigate side effects.

The bottom line: While retatrutide has a long road before it goes to market, the midstage trial results are exhilarating.