Key Takeaways
After 21 weeks of weekly VK2735 injections, patients had lost about 16%–19% of their body weight, compared with roughly 0% on placebo.
Switching to every-other-week dosing preserved up to 97% of that loss over the next 12 weeks, and monthly dosing preserved up to 90%. Patients switched to placebo kept 61%.
A small exploratory group that stayed on weekly 17.5 mg lost 21.7% of body weight by week 33 and had not reached a plateau.
VKTX traded up 26.5% late Tuesday morning, its largest intraday gain since February 2024.
The data come from a Phase 1 study of about 180 adults with exploratory weight endpoints. Phase 3 VANQUISH results cannot arrive before mid-2027.
What Did Viking Report About VK2735 on September 22?
Viking reported topline results from VK2735-102, a randomized, double-blind, placebo-controlled study in about 180 adults with obesity. Everyone received weekly injections of VK2735 or placebo for 21 weeks, then switched to monthly, every-other-week, weekly or placebo dosing for 12 more weeks. Weight loss held up much better on VK2735 than on placebo.
During the 21-week induction phase, doses rose every two weeks to final levels between 15 mg and 22.5 mg. Average weight loss ranged from 16.3% to 18.7% depending on dose, compared with 0.1% on placebo. In the combined VK2735 groups, 32% of participants lost at least a fifth of their starting weight, while no one on placebo did.
A separate exploratory group stayed on weekly 17.5 mg through week 33. That group of 13 people lost 21.7% of their starting weight, against a 0.3% gain on placebo, and was still losing weight at the end. Viking's headline figure of 22% placebo-adjusted weight loss comes from this group.
Chief executive Brian Lian credited VK2735's "unique and differentiated half-life and PK profile" for making longer dosing intervals workable. Viking also cited obesity specialist Louis Aronne, a former president of The Obesity Society, who argued that evidence for the heart and metabolic value of keeping 75% or more of lost weight is growing, and that both reduced-frequency schedules held patients inside that range. Viking discloses that Dr. Aronne is a paid consultant to the company.
Why Does Weight-Loss Maintenance Matter?
Weight-loss maintenance matters because obesity drugs are long-term treatments, and weight tends to return when patients stop or skip doses. In Viking's own study, people moved to placebo kept only 61% of their loss after 12 weeks. A drug that holds most of the loss on fewer, smaller doses could be easier for patients to stay on.
Each maintenance schedule was measured by the share of week-21 weight loss still in place at week 33:
Every other week, 17.5 mg weekly to 10 mg: 97% kept (12 patients).
Every other week, 15 mg weekly to 7.5 mg: 90% kept (13 patients).
Every other week, 17.5 mg weekly to 5 mg: 83% kept (12 patients).
Monthly, 17.5 mg weekly to 17.5 mg: 90% kept (11 patients), while the other four monthly arms kept 82%–86%.
Placebo: 61% kept (27 patients).
Viking also reported that stomach-related side effects during maintenance, including nausea, vomiting, diarrhea and constipation, occurred at rates similar to placebo. Early discontinuations were low across the trial.
The dose arithmetic is part of the appeal. On the best-performing every-other-week schedule, a patient takes 20 mg of VK2735 every four weeks, compared with 70 mg on weekly 17.5 mg dosing, or roughly 70% less drug. The monthly 17.5 mg arm uses 75% less. These are simple dose totals, not pricing claims, but lower drug exposure is one reason maintenance regimens draw attention.
Why Did VKTX Stock Jump 26%?
VKTX jumped because the data addressed a question hanging over every obesity drug: whether patients can realistically stay on it for years. Keeping up to 97% of weight loss on half as many injections, with placebo-like stomach side effects, made VK2735 look more practical as a long-term therapy, and it pointed to a monthly option that today's leading weekly injections lack.
What Are the Limits of the VK2735 Maintenance Data?
The main limit of the VK2735 maintenance data is the study design. VK2735-102 is a Phase 1 trial whose formal goals were safety, tolerability and drug levels, with weight change as an exploratory endpoint. Each maintenance arm had roughly 10 to 16 people, and the maintenance window lasted only 12 weeks. The results are encouraging, not proof of long-term efficacy.
Viking's
second-quarter update describes the trial as a Phase 1 dose-ranging study that began in October 2025. Four caveats follow from that design:
Small arms: single-arm results such as the 97% figure rest on 12 patients, so a few outcomes can move the average.
Short follow-up: three months of maintenance says little about what happens over a year or more.
Topline data: the figures are company-reported topline results, not yet a full peer-reviewed dataset.
No head-to-head test: comparisons with Zepbound or Wegovy trials mix different designs and populations, so they should be read loosely.
Funding is the other watch point. According to the same second-quarter report, Viking ended June with $502 million in cash, cash equivalents and short-term investments, down from $706 million at the end of 2025, after a quarterly net loss of $128.0 million. In August, the company
set up an at-the-market program to sell up to $500 million of stock over time. That gives Viking a way to raise money after a rally, and it gives shareholders a source of dilution to watch.
What Comes Next for VK2735 and VKTX?
The next VK2735 milestones are oral data and Phase 3 progress. Viking plans a second part of the maintenance study to test oral maintenance regimens, and it expects to start Phase 3 trials of the VK2735 tablet in the fourth quarter of 2026. The injectable Phase 3 VANQUISH trials are fully enrolled and running, according to
Viking's pipeline page.
VANQUISH-1: about 4,500 adults with obesity, fully enrolled by November 2025, testing weekly doses of 7.5 mg, 12.5 mg or 17.5 mg for 78 weeks.
VANQUISH-2: about 1,000 adults with obesity and type 2 diabetes, with enrollment completed in the first quarter of 2026.
Timing: 78 weeks after VANQUISH-1 finished enrolling points to mid-2027 at the earliest for its primary endpoint.
Near-term events: Viking is scheduled to present at Bernstein's healthcare forum on September 23–24 and the William Blair biotech conference on September 29–30.
Frequently Asked Questions About Viking Therapeutics and VK2735
Why did Viking Therapeutics stock go up?
On September 22, 2026, Viking reported that VK2735 patients kept up to 97% of their weight loss after switching to every-other-week injections and up to 90% on monthly injections, versus 61% on placebo. VKTX traded about 26% higher by late morning.
What is VK2735?
VK2735 is Viking's experimental dual agonist of the GLP-1 and GIP receptors, the same two receptors targeted by tirzepatide (Zepbound, Mounjaro). Viking is developing it as a weekly injection and as a daily tablet for obesity.
How much weight did patients lose on VK2735?
In the maintenance study, patients lost about 16%–19% of body weight after 21 weeks of weekly injections, and a small group that stayed on weekly 17.5 mg reached 21.7% by week 33. The earlier Phase 2 VENTURE trial showed up to 14.7% weight loss after 13 weeks.
Can VK2735 be taken monthly?
Possibly, for maintenance. In this study, monthly injections after weekly induction preserved 82%–90% of weight loss over 12 weeks. Viking has not yet tested monthly dosing in a Phase 3 trial.
Is VK2735 approved by the FDA?
No. VK2735 is investigational. The injectable is in Phase 3, and the oral version is expected to enter Phase 3 in the fourth quarter of 2026. Viking has not given an approval date.
Is there an oral version of VK2735?
Yes. In the Phase 2 VENTURE-Oral study, daily VK2735 tablets produced up to 12.2% weight loss after 13 weeks. Viking plans to test oral maintenance dosing in the next part of the maintenance study.
What are the main risks for VKTX stock?
Viking has no product revenue, reported a $128.0 million net loss in the second quarter of 2026 and can sell up to $500 million of stock through an at-the-market program. The stock also depends on trial results, including Phase 3 VANQUISH data that cannot arrive before mid-2027.