Viking Therapeutics says one dosing arm in its maintenance study retained 97% of its earlier weight loss.
That arm had 12 people in it.
The figure is real, and it comes from the company’s September 22, 2026, topline announcement. But the more useful numbers sit in the combined treatment groups and in two much larger Phase 3 obesity trials that remain underway.
Viking’s October 28 earnings update confirmed that both injectable Phase 3 trials have completed enrollment. Together, they involve approximately 5,500 people. The company expects the studies to finish in 2027.
That is the contrast driving the VK2735 story: a promising short-term maintenance signal from a small study, and a considerably larger clinical program that still needs to establish the drug’s efficacy and safety over time.
What VK2735 Is
VK2735 is an investigational obesity treatment developed by San Diego-based Viking Therapeutics.
It activates two metabolic hormone receptors, GLP-1 and GIP, the same receptor pair targeted by Eli Lilly’s tirzepatide, marketed as Zepbound and Mounjaro.
That makes VK2735 a dual GLP-1/GIP receptor agonist, although sharing receptor targets does not mean the two medicines have identical clinical effects.
Viking is developing VK2735 in two forms: a subcutaneous injection and an oral tablet.
The injectable version is being tested through the VANQUISH Phase 3 program, while the oral version entered its own SUNRISE Phase 3 program in October 2026.
VK2735 is not approved by the US Food and Drug Administration. Its efficacy and safety are still being evaluated in clinical research.
The distinction Viking hopes to establish goes beyond how much weight a drug can help people lose. The company is also testing whether patients might maintain their earlier reductions using injections every other week or once a month.
That would represent a different dosing proposition from the established weekly-injection model. Whether it offers a meaningful real-world advantage remains to be demonstrated.
The Maintenance Study Started With 21 Weeks of Weight Loss
Viking released topline results on September 22 from Part 1 of VK2735-102, a randomized, double-blind, placebo-controlled study involving approximately 180 adults with obesity who were otherwise healthy.
Participants had a body mass index of at least 30 and were assigned to treatment groups involving weekly VK2735 injections or placebo.
The first 21 weeks served as the induction period, during which the active-treatment doses were gradually increased toward targets of 15 mg, 17.5 mg, 20 mg or 22.5 mg per week.
By week 21, Viking reported mean body-weight reductions of 16.3% with 15 mg, 17.8% with 17.5 mg, 18.7% with 20 mg and 17.1% with 22.5 mg, compared with a 0.1% reduction in the placebo group.
These were company-reported least-squares mean estimates, and all four active-treatment groups differed statistically from placebo.
The next question was what happened when people who had already lost weight received fewer injections.
After the 21-week induction period, participants receiving VK2735 were assigned to additional dosing regimens, including injections every other week, injections once every four weeks or placebo.
A separate exploratory group continued weekly treatment.
The maintenance phase lasted 12 weeks, bringing the total observation period to 33 weeks.
That design makes the study useful for exploring less-frequent treatment. It does not make three months of maintenance equivalent to evidence of durable weight control over several years.
What “97% of Weight Loss Maintained” Actually Means
The headline number describes how much of the weight reduction achieved by week 21 remained at week 33.
It does not mean that 97% of participants maintained all their weight loss. It also does not mean participants lost another 97% of their weight.
For example, if a participant had lost 20% of starting body weight and retained 90% of that reduction, the remaining loss would be approximately 18% of starting body weight.
Viking’s results provide several different views of the maintenance effect.
The combined every-other-week group, including 37 participants, retained 90% of its earlier weight loss on average.
The combined monthly group, including 65 participants in the efficacy analysis, retained 85%.
The group transitioned to placebo, with 27 participants, retained 61% of its earlier weight loss.
Those combined active-treatment results were statistically superior to placebo in Viking’s reported analyses.
The standout 97% figure came from the 12-person subgroup that transitioned from 17.5 mg weekly injections to 10 mg every other week. It was one of three dosing regimens included in the combined every-other-week result.
That 97% estimate is therefore not independent of the 90% combined figure, and it should not be interpreted as representing the entire maintenance population.
There is another detail worth keeping.
In one small monthly-dose subgroup, Viking excluded a participant whose maintenance response exceeded 2.5 standard deviations from the cohort mean. The company reported that including this participant would have increased the subgroup’s retention estimate from 85% to 99%.
That exclusion was disclosed in the company’s results table and involved a separate monthly-dose cohort, not the 12-person group behind the 97% figure.
It illustrates how sensitive small subgroup estimates can be to individual observations.
The placebo result is also important. Participants who stopped active VK2735 during maintenance still retained an average of 61% of their earlier weight reduction after 12 weeks.
That finding shows some weight reduction persisted after treatment withdrawal during the short observation window. The data do not isolate how much of that persistence resulted from residual drug activity, lifestyle factors or other mechanisms.
Meanwhile, a separate exploratory group of 13 participants who continued 17.5 mg weekly injections reached 21.7% mean weight loss from baseline at week 33, with no plateau reported.
That is a different question from maintenance: it suggests continued weekly treatment may produce further weight reduction beyond the initial induction period.
The practical conclusion is narrower than the advertising-friendly headline.
VK2735 demonstrated encouraging short-term maintenance with less frequent injections. The combined groups provide a more reliable summary than the single best-performing small arm.
A maintenance study is only as long as its follow-up. Twelve weeks is a start, not an answer.
Safety During the Maintenance Phase
Viking also reported encouraging tolerability during the 12-week maintenance period.
Among participants receiving injections every other week, approximately 3% discontinued treatment because of an adverse event. The corresponding figure among monthly-dosing participants was approximately 2%. There were no adverse-event discontinuations in the placebo maintenance group.
Nausea was reported by 5% of participants in the combined every-other-week group and 4.5% in the monthly group, compared with none receiving placebo.
Overall treatment-emergent adverse events were reported by 38% of every-other-week participants, 49% of monthly participants and 52% of placebo participants.
The monthly safety analysis included 66 participants, one more than the monthly efficacy analysis. Those denominators reflect the different analysis populations reported by Viking.
Viking chief executive Brian Lian described the findings as supporting the potential viability of extended dosing schedules for weight maintenance.
The word “potential” matters.
These safety findings come from people who had already been through an induction period, rather than untreated patients starting VK2735 for the first time.
Gastrointestinal side effects can differ during initial treatment, dose escalation and maintenance. A low nausea rate among people who reach maintenance does not prove that the treatment will be equally well tolerated by everyone who begins it.
The results are also company-reported topline findings. They are not a substitute for a full peer-reviewed publication or the larger safety database expected from Phase 3.
The Trials That Will Decide Whether VK2735 Can Compete
The pivotal studies are considerably larger.
VANQUISH-1 enrolled approximately 4,500 adults with obesity or overweight and associated health conditions, without type 2 diabetes.
VANQUISH-2 enrolled approximately 1,000 adults with obesity or overweight and type 2 diabetes.
Both are randomized, double-blind, placebo-controlled Phase 3 trials evaluating weekly subcutaneous VK2735 doses of 7.5 mg, 12.5 mg and 17.5 mg over 78 weeks.
The primary outcome is percentage change in body weight from baseline compared with placebo. Secondary and exploratory outcomes include the proportions of participants reaching specific weight-loss thresholds and other safety and efficacy measures.
Viking confirmed in its October 28, 2026, corporate update that both trials have completed enrollment. The company expects them to finish in 2027.
Completed enrollment is not completed treatment, and it does not establish that the drug has met its Phase 3 endpoints.
Those larger trials are designed to test whether VK2735’s weight-loss performance and safety profile can withstand a much broader evaluation than the maintenance study.
Viking also plans extension studies beginning in the first quarter of 2027, allowing participants to continue treatment for up to another 52 weeks.
The VANQUISH-1 extension will include less-frequent dosing regimens, including every-other-week and monthly injections. Viking expects the extension results in 2028.
The oral program is moving forward as well.
Viking initiated the SUNRISE-1 and SUNRISE-2 Phase 3 studies in October. Each is designed to enroll approximately 560 adults and evaluate daily oral VK2735 doses of 27.5 mg, 35 mg and 55 mg against placebo over 68 weeks.
SUNRISE-1 studies adults without type 2 diabetes, while SUNRISE-2 includes adults with type 2 diabetes.
Those trials were underway at the October update, but Viking did not report that their enrollment was complete.
The dual development strategy matters. If successful, Viking could eventually offer both injectable and oral formulations containing the same active drug, potentially giving clinicians additional options for initial weight loss and ongoing maintenance.
That commercial possibility remains dependent on trial results, regulatory decisions and the performance of competitors already established in the obesity market.
The Money Behind the Trials, and Why Maintenance Is the Market
The expanded clinical program is expensive.
Viking reported a third-quarter net loss of $183.2 million, compared with $90.8 million in the corresponding quarter of 2025.
Research and development expenses increased to $166.8 million from $90.0 million a year earlier, reflecting the expansion of clinical trials, manufacturing activities and associated development work.
At the end of September, Viking held approximately $960 million in cash, cash equivalents and short-term investments.
That balance included roughly $550 million in net proceeds from recent financing transactions involving common stock and convertible senior notes.
The funding gives Viking resources to advance its Phase 3 programs and prepare potential commercial infrastructure. It does not guarantee that VK2735 will secure approval or compete successfully against existing obesity medicines.
The opportunity Viking is chasing is increasingly about maintenance.
Weight regain after stopping effective obesity treatment is a recognized clinical problem. In the STEP 1 extension study, participants who had discontinued semaglutide and structured lifestyle treatment regained approximately two-thirds of their earlier weight reduction over the following year.
That does not tell us how VK2735 will perform. It demonstrates why sustained treatment effects are a major development objective across the obesity field.
A treatment that safely preserves earlier weight loss with fewer doses could become valuable to patients, clinicians and healthcare systems. But fewer injections do not automatically establish better adherence, lower costs or improved long-term outcomes.
Viking is testing another version of that question in Part 2 of VK2735-102.
The second part, involving approximately 195 adults, will use a 21-week weekly-injection induction period followed by 12 weeks of maintenance using daily oral VK2735, every-other-week injections, monthly injections or placebo.
Viking expects those results in 2027.
Other developers are exploring the same broad commercial problem with different molecules and treatment strategies. We examined one such approach in our coverage of the ALV-100 PRESERVE obesity-maintenance study.
The competitive field is also moving quickly. Lilly’s retatrutide has generated substantial Phase 3 efficacy data, including direct evidence against semaglutide in type 2 diabetes, while approved treatments from Lilly and Novo Nordisk already command significant prescription volumes.
These are different studies in different populations. Their headline percentages cannot be used to establish which medicine would perform best in a direct VK2735 comparison.
For Viking, the essential questions now concern sustained effectiveness, tolerability, dosing convenience, manufacturing scale and whether the drug can justify its place among established competitors.
The obesity market’s next fight is not only about how much weight patients can lose. It is also about how they can keep it off, safely and sustainably.
The September maintenance results provide an encouraging early signal. The pooled results matter more than the highest single-arm percentage, and the larger randomized trials will provide a substantially stronger foundation for evaluating the drug.
For now, Viking’s 97% is a result from 12 people. The company’s real clinical test is still underway.
Primary maintenance source: Viking Therapeutics — VK2735 Maintenance Study Topline Results. September 22, 2026.
Financial and clinical update: Viking Therapeutics — Third Quarter 2026 Financial Results and Corporate Update. October 28, 2026.
SEC filing: Viking Therapeutics — Third Quarter 2026 Financial Results, Exhibit 99.1.
Oral Phase 3 program: Viking Therapeutics — Initiation of the SUNRISE Oral VK2735 Phase 3 Program. October 14, 2026.
Scientific context: Wilding JPH et al. Weight Regain and Cardiometabolic Effects After Withdrawal of Semaglutide: The STEP 1 Trial Extension. Diabetes, Obesity and Metabolism. 2022.
