Viking Therapeutics' VK2735 Maintains Weight Loss With Monthly Dosing; Shares Jump 24%

Viking Therapeutics (VKTX) said on Sept. 22, 2026, that patients maintained up to 90% of their weight loss after switching from weekly to once-monthly injections of its experimental obesity drug VK2735, and up to 97% on every-other-week dosing. The 12-week maintenance phase followed a 21-week induction period of weekly subcutaneous doses. Patients on monthly dosing maintained an average 85% of their week-21 weight loss versus 61% for placebo; every-other-week dosing averaged 90%, also versus 61% for placebo. An exploratory arm continuing weekly 17.5 mg doses showed mean weight loss of 21.7% from baseline at week 33, with no plateau. Gastrointestinal side effects were comparable to placebo during maintenance, and discontinuations were low. VK2735 is a dual GLP-1/GIP agonist, the same mechanism as Eli Lilly's tirzepatide. Viking is running Phase 3 trials and developing an oral formulation. Shares rose roughly 24% by Tuesday morning.