Viking obesity drug shows durable weight loss

Viking Therapeutics (VKTX) reported topline results from a randomized, double-blind, placebo-controlled maintenance study of VK2735 in approximately 180 adults with obesity. Participants first received 21 weeks of once-weekly subcutaneous VK2735 or placebo as an induction phase. At Week 21, VK2735-treated cohorts achieved about 16% to 19% mean weight loss from baseline, compared with approximately 0% for placebo.

Across the combined VK2735 treatment groups at Week 21, 98% of participants achieved at least 5% weight loss, 90% reached at least 10%, 65% achieved at least 15%, and 32% reached at least 20% weight loss. These results highlight a broad distribution of substantial weight reduction that was not observed in the placebo group, where the proportions at the same thresholds were 13%, 0%, 0%, and 0%, respectively.

Following the induction period, participants entered a 12-week maintenance phase with less-frequent dosing schedules. Subjects who transitioned from weekly VK2735 to every-other-week dosing maintained up to 97% of the mean weight loss achieved during induction. In contrast, those switched to placebo maintained 61% of their prior weight loss over the same period.

Participants who transitioned to monthly VK2735 dosing maintained up to 90% of their induction-phase weight loss, again compared with 61% in the placebo maintenance group. Separation between active treatment and placebo was observed as early as four weeks after the transition to less-frequent dosing for both every-other-week and monthly regimens, underscoring the durability of VK2735’s effect.

An exploratory control arm evaluated participants who continued to receive weekly 17.5 mg doses of VK2735 through Week 33. In this cohort of 13 participants, mean weight loss reached 21.7% from baseline at Week 33, with statistical significance reported versus baseline (p<0.0001). This provides an early indication of continued weight loss beyond the initial 21-week induction when weekly dosing is maintained.

During the 12-week maintenance phase, VK2735 demonstrated an encouraging safety and tolerability profile. Reported rates of gastrointestinal adverse events, including nausea, vomiting, diarrhea and constipation, were described as not meaningfully different from placebo. Discontinuation rates during maintenance were characterized as low, supporting the feasibility of longer-term use.

Viking also indicated plans to explore oral maintenance dosing regimens in a subsequent part of the VK2735-102 program. The move to assess oral options reflects an effort to expand potential dosing formats while building on the durability data seen with subcutaneous administration in this trial.

The release of the VK2735 maintenance study results prompted a sharp positive reaction in Viking Therapeutics (VKTX)’ share price. News coverage cited pre-market or pre-open gains in a range of roughly 27% to 40% on the day of the announcement. The stock move reflected investor focus on the combination of robust weight-loss efficacy, durability with less-frequent dosing, and the reported safety profile from the maintenance phase.