Part 2 of the VK2735 maintenance study tests whether daily or weekly oral tablets can hold weight loss first achieved with weekly subcutaneous injections.
Viking Therapeutics has begun Part 2 of its maintenance dosing study of VK2735, testing whether daily or weekly oral tablets of the dual glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist can sustain weight loss first achieved with weekly subcutaneous injections.¹ The trial, disclosed October 6, 2026, will also evaluate monthly and every-other-week injection schedules.¹
The study addresses a practical question in obesity pharmacotherapy: how patients move from intensive weight loss to a regimen they can sustain for years. For developers and manufacturers, the answer bears on formulation strategy, dose-strength portfolios, and long-term drug substance demand.
"Our recent top-line results from Part 1 of this study demonstrated the potency and differentiated profile of VK2735 in the setting of both weight loss induction and potentially longer-term maintenance,” said Brian Lian, Ph.D., chief executive officer of Viking.¹ “We are eager to continue this study with the initiation of Part 2, which will explore multiple regimens, both oral and subcutaneous, with the potential to provide greater optionality and flexibility to best align with a patient's individual weight loss journey."
The randomized, double-blind, placebo-controlled study will enroll approximately 195 otherwise healthy adults with obesity, defined as a body mass index of 30 kg/m² or higher.¹ As in Part 1, all participants receive weekly subcutaneous VK2735 or placebo for 21 weeks.
At Week 21, they move to one of several maintenance options: daily oral doses, weekly oral doses, monthly or every-other-week subcutaneous doses, or placebo.¹ The formal objectives are safety, tolerability, and pharmacokinetics across these regimens.
Change in body weight from baseline, and from Week 21 to the end of the study at Week 33, is assessed only as an exploratory endpoint.¹
Part 1, reported September 22, 2026, enrolled approximately 180 adults with obesity.² After 21 weeks of weekly injections, mean weight loss across dose cohorts ranged from about 16% to 19%, compared with roughly 0% for placebo.²
During the subsequent 12-week maintenance phase, participants switched to every-other-week dosing retained up to 97% of their induction weight loss, and those switched to monthly dosing retained up to 90%, versus 61% among participants switched to placebo.² Rates of gastrointestinal adverse events during maintenance were reported as similar to placebo.²
These data come from a company announcement rather than a peer-reviewed publication, and individual maintenance cohorts were small, ranging from 10 to 16 participants.²
Evidence from the incretin class indicates that stopping therapy carries a measurable cost. In the phase 3 SURMOUNT-4 randomized withdrawal trial, adults who switched from tirzepatide to placebo after a 36-week lead-in regained 14.0% of body weight over 52 weeks, while those who continued treatment lost an additional 5.5%.³
Tirzepatide and the GLP-1 receptor agonist semaglutide are both approved by the FDA.¹ Lian framed the Part 2 design around that persistence challenge.
"Adherence to therapy is critical to achieving the long-term benefits of weight loss, including reduction of cardiovascular risk, improved physical function, and enhanced quality of life,” he said. “We believe flexibility and optionality are key to increasing adherence to treatment and improving long-term weight management - from induction to maintenance.
“We were pleased to report positive results from our recent subcutaneous maintenance study and are excited by the potential to validate additional maintenance regimens as well. In doing so, we expect to offer patients and their clinicians a broad range of highly effective and convenient tools to achieve personalized weight loss goals. We look forward to reporting the results from Part 2 of this study in 2027.”¹
In the phase 2 VENTURE trial, 13 weekly subcutaneous doses of VK2735 produced mean weight reductions of up to 14.7% from baseline, with most adverse events graded mild or moderate; full results were published in Obesity in January 2026.⁴ The injectable formulation is now in two fully enrolled 78-week phase 3 trials: VANQUISH-1, with approximately 4,500 adults without type 2 diabetes, and VANQUISH-2, with approximately 1,000 adults with type 2 diabetes.¹
Because weight change is exploratory, any maintenance signal from Part 2 will need confirmation in larger, longer trials. A 12-week maintenance window is brief for a chronic disease, and enrolling otherwise healthy adults limits generalizability to patients with comorbidities.¹
Comparisons with SURMOUNT-4, which used a different design and duration, should be made cautiously.³
For manufacturing and supply teams, a regimen spanning daily tablets, weekly tablets, and injections at two- and four-week intervals would mean supporting several dosage forms and strengths of a single molecule. Whether that breadth translates into better long-term persistence than a single weekly regimen remains untested.
Sources
