Eli Lilly weight loss drug retatrutide clears obesity trial

Eli Lilly on Thursday said its next-generation drug cleared a crucial late-stage trial in patients with obesity, delivering significant weight loss across doses. 

The results bring Lilly one step closer to filing for approval of the weekly injection, called retatrutide, which works differently from existing shots and pills from both Lilly and Novo Nordisk. It also appears to be more effective than those options.

The highest dose of retatrutide helped patients lose 28.3% of their weight — or 70.3 pounds — on average over 80 weeks, compared with 2.2% with placebo, when evaluating only patients who stayed on the drug.

Roughly 45% of the 2,500 patients in the Phase 3 trial achieved 30% or more weight loss, Lilly said. 

The highest dose also helped patients with a body mass index of 35 or above who participated in an extension of the study lose 30.3% of their weight on average over 104 weeks. That BMI threshold puts people at higher risk of cardiovascular complications or diabetes.

While the drug appeared to show higher rates of certain gastrointestinal side effects, such as nausea and diarrhea, especially at the highest dose, they were generally consistent with a previous Phase 3 trial of retatrutide in patients with obesity and a type of knee arthritis pain. Some analysts previously said those side effects highlight the speed and strength of the drug’s weight loss.

A lower dose of retatrutide that Lilly tested in the latest study was also associated with fewer discontinuations due to side effects.

Dan Skovronsky, Lilly’s chief scientific and product officer, called the 30% weight loss an “incredible number to see,” as it has previously only been associated with bariatric surgery. 

“We haven’t seen that level of weight loss before with these kinds of medicines,” Skovronsky told CNBC in an interview. 

Around 65% of people taking the highest dose of retatrutide also achieved a BMI of less than 30, which falls under the threshold for obesity, at 80 weeks.

Ahead of the results, some analysts said they were expecting to see weight loss higher than that seen with Lilly’s blockbuster weight loss drug Zepbound, which is around 20% to 22%. 

The data is the third late-stage result to date on retatrutide, which succeeded in a diabetes trial earlier this year and cleared a smaller study on patients with obesity and a type of knee arthritis in December. Lilly is betting big on retatrutide as the next pillar of its obesity portfolio after its injection Zepbound and newly launched pill, Foundayo. 

In a January note, TD Cowen analysts estimated that retatrutide could rake in sales of $3.8 billion in 2030. 

Retatrutide is also critical to the drugmaker’s plan to maintain its market share majority over Novo in the booming market for weight loss and diabetes drugs. Some analysts estimate the segment could be worth about $100 billion by the 2030s.