Obesity drug outlook: Hopes for stronger treatments, adherence remains a hurdle

Investing.com -- Bernstein analysts see significant growth potential in the obesity drug market, but the firm cautioned in a note this week that patient adherence remains a major challenge. 

Following an expert event with Christos Mantzoros, an endocrinologist and Harvard professor, Bernstein outlined key takeaways on current treatments, next-generation drugs, and future indications.

“The weight-loss market is evolving quickly. Novo pioneered it in 2021 when launching Wegovy (semaglutide of GLP-1 class), and Lilly (covered by our US colleague Courtney Breen) followed up at end-2023 with Zepbound (tirzepatide, dual mechanism of action GLP1/GIP),” said Bernstein.

“These two products dominated the $14bn market last year. Some $9bn of this went to Novo, but Lilly is catching up in volume terms in the US.”

Despite this growth, adherence remains a significant barrier. Bernstein added that according to Mantzoros, fewer than 50% of patients continue treatment after a year due to efficacy concerns, side effects, and cost. 

They explained that patients often expect rapid results based on clinical trials or social media, but real-world weight loss can be slower. 

Moreover, gastrointestinal issues—including vomiting and diarrhea in over 30% of patients—are said to be common. 

Mantzoros reportedly suggests starting treatment “slow and low” to minimize the effects. Cost is another factor, as insurance coverage is said to be often insufficient for long-term treatment, even though obesity is a chronic condition.

Looking ahead, Bernstein notes that next-generation drugs aim to improve efficacy and convenience. Mantzoros highlighted Lilly’s Orforglipron, a non-peptide oral drug targeting less severe cases, and Lilly’s Retatrutide, which shows ~25% weight loss potential but may bring increased side effects.

While early research suggests potential neurological and cancer benefits, Bernstein  said it remains skeptical “given the previous failure of diabetes and cardio products that had theoretical benefit.”