Viking's stock tanks after obesity pill delivers weight loss with side effects

Viking Therapeutics' oral obesity drug VK2735 showed promising weight loss in a Phase 2 trial but triggered high dropout rates due to side effects, causing shares to plunge 44%.

Backstory: Viking is a frontrunner in developing an oral alternative to blockbuster injectable obesity drugs. VK2735 mimics gut hormones GIP and GLP-1, similar to the leading GLP-1 treatments from Novo Nordisk and Eli Lilly, but its oral formulation could be a game-changer in the booming obesity market.

The trial: VK2735 helped patients lose up to 12% of body weight in 13 weeks, surpassing the 8% expected by analysts.

Yes, but: High dropout rates (up to 38% in high dose groups) raise red flags about tolerability, especially with vomiting hitting 33% of the higher dose and GI side effects common in all groups.

Why it matters: The high rate of treatment discontinuation raises doubts about VK2735’s competitiveness, especially against more advanced rivals from Eli Lilly and Novo Nordisk.

Big picture: With rivals Lilly and Novo Nordisk advancing oral candidates, Viking faces pressure to prove its drug is not only effective but sustainable. A low-dose regimen could offer a path forward, especially for weight maintenance after initial loss.

What’s next: Viking is expected to design a pivotal Phase 3 trial, likely focusing on lower or stepped-down dosing strategies. The company is also developing an injectable version, with results due in 2027.