Viking Therapeutics Initiates Oral Maintenance Dosing Study for VK2735: What the GLP-1/GIP Dual Agonist's Two-Part Programme Tells Researchers About the Weight-Regain Problem

Key takeaways

• Viking Therapeutics announced on 6 October 2026 the initiation of Part 2 of its exploratory VK2735 maintenance dosing study, focused on oral tablet regimens following subcutaneous induction.
• Part 1 top-line results, released on 22 September 2026, showed weekly subcutaneous VK2735 at 17.5 mg produced approximately 22% placebo-adjusted weight loss at Week 33 with no plateau; less-frequent subcutaneous maintenance preserved up to 97% of that loss.
• Part 2 will enrol approximately 195 adults with obesity and is randomised, double-blind, and placebo-controlled; results are expected in 2027.
• Two fully enrolled Phase 3 studies — VANQUISH-1 (approximately 4,500 participants without type 2 diabetes) and VANQUISH-2 (approximately 1,000 with type 2 diabetes) — are running in parallel, evaluating weekly subcutaneous dosing for 78 weeks.
• The oral maintenance question is strategically important across the GLP-1/GIP class: long-term obesity management requires treatment regimens patients can sustain, and oral peptide tablets represent a potential step-down option from injectable induction.

The compound and its mechanism

VK2735 is a dual agonist of the glucagon-like peptide-1 (GLP-1) receptor and the glucose-dependent insulinotropic polypeptide (GIP) receptor, being developed in both subcutaneous and oral formulations for obesity and related metabolic disorders. Viking Therapeutics describes VK2735 as a clinical-stage GLP-1/GIP receptor agonist; it is not approved in any jurisdiction. The dual receptor mechanism mirrors the pharmacological logic of tirzepatide (Mounjaro/Zepbound), which targets the same two receptors, though VK2735 is a structurally distinct molecule with a differentiated formulation strategy.

The peptide is designed to suppress appetite and slow gastric emptying via the GLP-1 axis while simultaneously promoting metabolic clearance of dietary lipids via GIP receptor activity — a combination that in approved agents has produced weight loss outcomes superior to GLP-1 mono-agonism alone.

What Part 1 showed

Viking Therapeutics' 22 September 2026 press release reported positive top-line data from the subcutaneous-focused arm of the maintenance study. Part 1 was a randomised, double-blind, placebo-controlled trial in approximately 180 adults with a body mass index of 30 kg/m² or higher.

During the 21-week induction phase, weekly subcutaneous VK2735 produced placebo-adjusted weight reductions of approximately 16% to 19% across dose groups, according to company-reported top-line data. An exploratory cohort continuing on weekly 17.5 mg dosing reached approximately 22% placebo-adjusted loss by Week 33 with no apparent plateau. According to the same release, 98% of VK2735 participants achieved at least 5% weight loss, 65% achieved at least 15%, and 32% achieved 20% or more.

The maintenance phase — the core scientific question Part 1 was designed to address — assessed what happens when weekly injections are replaced by less-frequent regimens. According to top-line data reported by Viking, participants who transitioned to every-other-week VK2735 preserved up to 97% of prior weight loss at Week 33, while those on monthly dosing maintained up to 90%, compared with 61% for participants switched to placebo. Gastrointestinal adverse event rates during the maintenance period were described as comparable to placebo — a tolerability characteristic that distinguishes the maintenance phase from the often GI-heavy induction period typical of the GLP-1 class.

These are company-reported top-line figures and have not yet been published in peer-reviewed form. Researchers should treat them as preliminary until full study data are available for independent assessment.

Part 2: the oral arm begins

Viking confirmed on 6 October 2026 that Part 2 of the maintenance study has been initiated. The trial is randomised, double-blind, and placebo-controlled, enrolling approximately 195 otherwise healthy adults with obesity. All participants will first receive weekly subcutaneous VK2735 or placebo for 21 weeks, after which they will transition to one of several maintenance regimens: daily oral tablets, weekly oral tablets, monthly subcutaneous injection, every-other-week subcutaneous injection, or placebo.

The primary objectives of Part 2 are to evaluate the safety, tolerability, and pharmacokinetic profile of VK2735 across these oral and subcutaneous maintenance regimens, with exploratory endpoints assessing body-weight change from both baseline and Week 21. According to Rallies, results from the oral-focused phase are expected in 2027.

Brian Lian, chief executive of Viking, framed the rationale as adding "greater optionality and flexibility to best align with a patient's individual weight loss journey," as quoted in the company's 6 October press release.

Oral dose levels to be evaluated in the maintenance phase were described by Viking's CEO as 17.5 mg, 27.5 mg, and 35 mg, levels described as relatively lower than those used in the Phase 2 weight-loss study and therefore potentially better tolerated.

Phase 3 context: VANQUISH-1 and VANQUISH-2

The maintenance programme runs alongside two fully enrolled Phase 3 studies. VANQUISH-1 is a 78-week randomised controlled trial in approximately 4,500 adults without type 2 diabetes, and VANQUISH-2 evaluates weekly subcutaneous VK2735 in approximately 1,000 adults with type 2 diabetes who have obesity or are overweight. Both studies evaluate four treatment arms: 7.5 mg, 12.5 mg, 17.5 mg, and placebo, dosed weekly.

The Phase 3 trials address regulatory registration in the standard sense; the maintenance programme is exploratory and is not on the path to approval by itself. Researchers interested in the clinical pipeline of GLP-1/GIP dual agonists will note that VANQUISH readouts — not yet reported — will be the decisive data for any eventual regulatory submission.

Why the oral maintenance question matters

The broader clinical challenge in obesity pharmacology is not merely inducing weight loss but sustaining it. Abrupt discontinuation of GLP-1-class agents is consistently associated with weight regain. Part 1 of the Viking maintenance study offers early evidence that less-frequent injectable dosing may substantially preserve prior weight loss — a finding of practical relevance if confirmed.

The oral component adds a distinct dimension. Should oral tablet maintenance prove effective following subcutaneous induction, it would widen the practical options available to clinicians and patients, reduce the injection burden associated with long-term treatment, and position VK2735 as a more flexible programme than competitors with subcutaneous-only pipelines.

This question is not unique to VK2735. Novo Nordisk's once-daily oral semaglutide (Wegovy tablet) recently generated real-world observational data from the OCTANE study, presented at EASD 2026, showing that patients switching from injectable semaglutide or tirzepatide to oral semaglutide lost an average of 4.1% of body weight over three months — though the retrospective analysis lacked a comparator group. The direction of evidence across the class suggests sustained interest in oral peptide formulations as a step-down or continuation strategy.

Regulatory and sourcing considerations for UK research labs

VK2735 is a clinical-stage investigational compound. It is not approved by the FDA, MHRA, or EMA, and is not available for clinical use or general research procurement in the United Kingdom. Any procurement would fall within the research-use-only framework applicable to investigational compounds, requiring adherence to MHRA import licensing requirements and institutional ethical governance.

Viking Therapeutics has not disclosed a UK trial site for either the maintenance study or the Phase 3 VANQUISH programme. Researchers wishing to follow the programme should monitor ClinicalTrials.gov for updates on VANQUISH-1 and VANQUISH-2 enrolment sites.

What to watch

• Part 2 top-line results (2027): Whether oral maintenance achieves comparable weight-loss preservation to the subcutaneous regimens in Part 1 will be the central data point.
• VANQUISH-1 readout: The pivotal Phase 3 result in non-diabetic adults will determine the regulatory trajectory and is the key event for organisations tracking GLP-1/GIP dual agonist approvals.
• Comparative tolerability of oral doses: The relatively lower doses proposed for oral maintenance may carry a more favourable GI profile, which the Part 2 safety objectives are designed to characterise.
• Peer-reviewed publication of Part 1 data: The 22 September top-line results remain company-reported; independent assessment will require full publication or conference presentation with methodology disclosed.