VK2735 Phase II

What It Is

VK2735 is an investigational dual GIP/GLP-1 receptor agonist being developed by Viking Therapeutics (San Diego, CA) for chronic weight management and metabolic disease. Mechanistically it occupies the same receptor space as Eli Lilly's tirzepatide — simultaneous activation of the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor — but as a distinct molecular entity with Viking's proprietary peptide engineering. The program includes both a once-weekly subcutaneous formulation and an oral formulation, with the oral program offering meaningful differentiation against tirzepatide's injection-only market position.

Viking has advanced VK2735 through Phase 1 pharmacokinetic / safety and Phase 2 efficacy trials. The headline efficacy data from the VENTURE Phase 2 trial (reported in 2024) showed up to ~14.7% mean body weight reduction at 13 weeks at the highest tested dose in adults with obesity, with dose-dependent weight loss across cohorts and a tolerability profile consistent with the GIP/GLP-1 class (GI adverse events as the dose-limiting signal). A 13-week reduction of this magnitude suggests a rate of loss approaching or exceeding tirzepatide's SURMOUNT-1 trajectory at comparable dose ranges, though direct head-to-head comparison requires longer time points and matched study populations.

The oral VK2735 program is strategically important because oral once-daily obesity therapeutics are a large unmet commercial demand that injection-only GLP-1 / GIP-GLP-1 agents do not fill. Viking's oral VK2735 is in Phase 2 with early data indicating meaningful weight loss and acceptable tolerability, competing against Eli Lilly's oral orforglipron program and Novo Nordisk's oral semaglutide / amycretin pipeline.

As of April 2026, VK2735 is investigational — not FDA-approved, not available by prescription, and not appropriately available through research-chemical supply for clinical use. The Viking Therapeutics development program is the only legitimate access path, which means trial participation. Research-chemical vendors have marketed "VK2735" products in recent years; these are unregulated, may or may not be the molecule claimed on label, and are not an appropriate alternative to a legitimate pharmaceutical product in active development.

Mechanism of Action

VK2735 activates both incretin receptors simultaneously, engaging the same dual-agonist biology that tirzepatide validated.

• GLP-1 receptor activation — Glucose-dependent insulin secretion from pancreatic β-cells, inappropriate glucagon suppression from α-cells, delayed gastric emptying (transient, with tachyphylaxis over weeks), central appetite suppression via GLP-1R populations in the hindbrain and hypothalamus.
• GIP receptor activation — Potentiated glucose-dependent insulin secretion, adipose-tissue metabolic improvement (insulin sensitivity in subcutaneous adipose, improved lipid buffering), central hypothalamic satiety, and preclinically-demonstrated mitigation of GLP-1-associated nausea via hypothalamic GIP-R circuits.
• Dual-agonist synergy — In the tirzepatide-validated paradigm, co-activation of GIP and GLP-1 produces greater weight loss and glycemic improvement than selective GLP-1 alone, with improved tolerability at high efficacy doses. VK2735's observed efficacy in VENTURE supports the translatability of this paradigm to non-Lilly molecules.
• Central appetite suppression — "Food noise" reduction, reduced hedonic eating, earlier satiation — the subjective patient experience is expected to mirror the GLP-1 / dual-incretin class.
• Adipose remodeling — Anticipated class-consistent visceral-fat-preferring weight loss, based on tirzepatide SURPASS-3 MRI and SURMOUNT-1 imaging substudy findings.
• Hepatic effects — Expected class-consistent MASH improvement downstream of weight loss and improved insulin sensitivity. Viking has not yet reported MASH-specific histology data.
• Oral formulation bioavailability — Viking's oral VK2735 formulation is a differentiator. Oral absorption of a peptide-class GIP/GLP-1 agonist is technically demanding; the specific formulation approach (permeation enhancer, capsule design) affects PK variability. Phase 2 oral data has shown absorption adequate for meaningful weight-loss signal.
• Pharmacokinetics supporting weekly dosing — Viking has engineered VK2735 SubQ to support once-weekly administration; exact half-life and albumin-binding strategy are Viking proprietary.
• Receptor-binding balance — Dual-agonist efficacy depends on the relative GIP vs GLP-1 affinity ratio. Tirzepatide has roughly equivalent GIP affinity to native GIP but ~5× weaker than native GLP-1. VK2735's published binding-affinity profile has not been fully disclosed but is reported to be within the same general range supporting dual activation.
• Central nervous system engagement — Like tirzepatide and semaglutide, VK2735 is expected to engage hindbrain and hypothalamic incretin-receptor populations that mediate the core appetite-suppression phenotype. Central engagement is dose-dependent and time-extended relative to peripheral effects.
• Insulin secretion glucose-dependence — As a class feature, dual incretin agonists stimulate insulin secretion only in the context of elevated glucose. This minimizes intrinsic hypoglycemia risk — a major class advantage over insulin and sulfonylureas.
• Glucagon suppression — GLP-1R activation suppresses inappropriate α-cell glucagon release. VK2735 is expected to exhibit this class-consistent effect.
• Gastric emptying and satiety — Acute gastric emptying delay contributes to initial satiety and GI tolerability signals; sustained weight loss is driven by central rather than gastric mechanisms. Tachyphylaxis of gastric effects develops over ~2 weeks.

What the Research Shows

• VENTURE Phase 2 (SubQ VK2735, 2024) — 13-week randomized trial in adults with obesity. Up to 14.7% body weight reduction at the highest tested dose vs placebo. Dose-dependent across cohorts. GI adverse-event profile consistent with the GIP/GLP-1 class. Topline data reported by Viking Therapeutics and characterized in peer-reviewed obesity-medicine presentations (Bays HE et al., Obesity / ObesityWeek 2024 and subsequent follow-on publications).
• Phase 1 SAD/MAD (SubQ) — Dose-ranging single- and multiple-ascending-dose studies establishing PK, tolerability, and dose-response prior to VENTURE.
• Oral VK2735 Phase 1 — Demonstrated PK adequate for oral once-daily dosing with early weight-loss signal.
• Oral VK2735 Phase 2 (planned / ongoing) — Viking's oral program advancing in parallel with the SubQ development pathway.
• Phase 3 program — Planned but not yet initiated at press time of Viking's 2024 investor communications. Multi-cohort obesity Phase 3 program expected 2025–2027 pending FDA end-of-Phase-2 meeting outcomes.
• Dual incretin class context — VK2735 benefits from the tirzepatide-established proof-of-concept for dual GIP/GLP-1 agonism in obesity. Class risks (pancreatitis, thyroid C-cell, gastroparesis, gallbladder) apply.

Human Data

• Phase 1 SubQ VK2735 — Completed dose-ranging safety / PK in healthy volunteers and obese volunteers.
• VENTURE Phase 2 SubQ (NCT05946356 and follow-on) — 13-week obesity Phase 2. Topline 14.7% weight reduction at highest dose.
• Phase 1/2 oral VK2735 — Early weight-loss signal with oral formulation.
• Phase 3 SubQ — Planned pending end-of-Phase-2 FDA interactions.
• Oral VK2735 Phase 2 — Viking advancing in 2025–2026.
• No CV outcomes trial — No dedicated CVOT for VK2735 as of April 2026.
• No MASH histology trial — Not yet initiated.
• Competitive landscape — Tirzepatide (FDA-approved), retatrutide (Phase 3, triple GIP/GLP-1/glucagon), semaglutide (FDA-approved), orforglipron (oral GLP-1 Phase 3), Viking's own oral VK2735 — crowded and rapidly evolving.
• VENTURE Phase 2 context — The 13-week trial enrolled adults with obesity across multiple dose arms plus placebo. Dose-dependent weight loss was observed at each escalation step, and the 14.7% topline at the highest dose has been the headline figure driving market interest. Phase 2 safety data were consistent with the GIP/GLP-1 class, with GI adverse events as the primary tolerability signal.
• Oral VK2735 strategic importance — The oral formulation program is strategically critical because oral incretin class therapeutics address a large unmet demand that injection-only products do not fill. Viking's oral program is pursuing a Phase 2 pathway with initial data suggesting meaningful weight loss capability; the durability, PK reproducibility across patients, and food-effect considerations will determine whether oral VK2735 can compete with Eli Lilly's oral orforglipron and Novo Nordisk's oral amycretin pipeline.
• Metabolic disease beyond obesity — Viking has publicly discussed additional metabolic-disease indications (type 2 diabetes, MASH) for VK2735 pending Phase 2 obesity-program success. None of these parallel programs has advanced past Phase 2 as of early 2026.
• Retatrutide comparison — Eli Lilly's triple agonist is the weight-loss ceiling competitor. Retatrutide Phase 2 (Jastreboff et al., NEJM 2023; PMID 37366315) demonstrated 24.2% weight loss at 48 weeks at 12 mg, and Rosenstock et al. Lancet 2023 (PMID 37385275) demonstrated T2D efficacy. VK2735 does not include glucagon-receptor agonism and is unlikely to reach retatrutide's efficacy ceiling, but may offer better GI tolerability or oral-formulation access.

Dosing from the Literature

Reconstitution & Storage

VK2735 in legitimate use is a trial-pharmacy-dispensed clinical supply. Research-chemical supply is not appropriate for clinical use.

• Research-chemical caveat — Vendors marketing "VK2735" research peptide have appeared since 2024. There is no independent way for a community user to verify identity, purity, stability, or concentration of such products; an investigational-drug pharmaceutical molecule being sold by unregulated suppliers is a supply channel with systematic quality risk.
• Clinical-trial supply — If participating in a Viking clinical trial, all formulation, reconstitution, storage, and administration follow the trial investigator brochure.
• Stability — Peptide-class GIP/GLP-1 agonists generally require refrigerated storage in solution; oral formulations have their own stability requirements per Viking's capsule/tablet design.

→ Use the Kalios Peptide Calculator for research-context dosing math

Side Effects & Risks

• Gastrointestinal (class-consistent) — Nausea, vomiting, diarrhea, constipation. Consistent with the GIP/GLP-1 agonist class. Dose-limiting at higher doses in VENTURE.
• Early-stage safety data — Limited safety database. Class signals from tirzepatide (pancreatitis, thyroid C-cell tumors in rats, gastroparesis, gallbladder disease, AKI from volume depletion) are relevant by class similarity but not yet specifically validated in VK2735.
• Hypoglycemia (theoretical class signal) — Class risk increases when combined with insulin or sulfonylureas.
• Lean mass loss during rapid weight loss — Class-common. Protein intake (≥1.6 g/kg/day) and resistance training are the best-validated countermeasures.
• Oral contraceptive efficacy — Delayed gastric emptying may affect oral absorption of other drugs including OCP (class effect).
• Pre-operative aspiration risk — Class-relevant perioperative consideration.
• Pregnancy / lactation — Not studied; avoid.
• Research-chemical product risk — If a community user obtains "VK2735" from a research-chemical supplier, the product is unregulated and carries material identity / purity / dose-accuracy risk.
• WADA status — Not specifically prohibited on the WADA Prohibited List as a named compound. Class (GIP/GLP-1 agonists) is not listed.

Bloodwork & Monitoring

For any GIP/GLP-1 agonist class use (investigational or otherwise), standard metabolic / weight-management monitoring applies.

• HbA1c + fasting glucose — Baseline and 3–6 months.
• CMP — Liver enzymes, renal function, electrolytes.
• Lipid panel — Baseline and periodic.
• Lipase / amylase (selective) — If abdominal pain develops.
• DEXA body composition — Track lean-mass preservation during active weight loss.
• BP + heart rate — Class-consistent SBP reduction.
• Thyroid exam (selective) — Class-level C-cell tumor signal (rat); clinical relevance uncertain.
• Vitamin D, B12, iron — Reduced food volume during weight loss can cause micronutrient dips.

Quick Compare — VK2735 vs Tirzepatide vs Retatrutide vs Semaglutide

The GIP/GLP-1 / incretin-class weight-loss landscape as of April 2026:

• Efficacy ceiling — Retatrutide > VK2735 (extrapolated) ≈ tirzepatide > semaglutide on reported Phase 2/3 weight-loss data.
• Evidence maturity — Tirzepatide and semaglutide have the deepest outcome data. VK2735 is early. Retatrutide is advancing.
• Oral differentiation — VK2735 and semaglutide are the two leading oral contenders in the incretin space. Oral orforglipron (Eli Lilly GLP-1 only) is a third.
• Practical implication — For patients needing a weight-loss therapy today, tirzepatide or semaglutide are the FDA-approved choices. VK2735 is a pipeline story, not a clinical choice.

→ See Tirzepatide profile  •  → See Retatrutide profile  •  → See Semaglutide profile

Supportive Nutrition & Adjuncts

Any GIP/GLP-1-class weight-loss program — approved (tirzepatide) or investigational (VK2735) — is only as healthy as its body-composition outcome. Rapid pharmacologic weight loss mobilizes fat automatically but risks lean mass, bone density, and micronutrient status without deliberate support.

• Protein (1.6–2.2 g/kg goal body weight) — The single most-important lever for lean-mass preservation during any rapid weight loss. Distribute across 3–4 feedings of ≥30 g.
• Resistance training (2–4×/week) — Repeatedly validated across bariatric and pharmacologic weight-loss literature as the lean-mass-preservation behavioral intervention. Walking alone does not preserve lean mass at GIP/GLP-1 class rates of loss.
• Creatine monohydrate (3–5 g) — Lean-mass preservation, training capacity at reduced calories.
• Electrolytes — Sodium, potassium, magnesium are frequently depleted with GI-heavy early titration; inadequate sodium compounds transient hypotension.
• Vitamin D (40–60 ng/mL target) — Baseline and monitor.
• Vitamin B12 + folate — Reduced food volume drops these predictably.
• Calcium + vitamin K2 — Bone density is at risk during any rapid weight loss.
• Fiber (25–35 g) — Constipation is class-common and fiber-solvable before it becomes dose-limiting.
• Things to avoid during active use — Very low-protein / high-carbohydrate dieting, chronic alcohol (impairs recovery, exacerbates GI), skipped resistance training, dehydration during GI upset.

What to Expect — Timeline (From Class Analogues)

VK2735-specific timeline data is limited to the 13-week VENTURE Phase 2. The below is class-pattern extrapolation from tirzepatide's SURMOUNT experience, adjusted for VK2735's observed faster 13-week trajectory.

• Week 1 (starting titration dose) — First reduced hunger / smaller portions within 1–3 days post-injection. Some early GI effects (mild nausea, early satiety).
• Weeks 2–4 — Appetite-effect steady state. Early weight loss of 2–4 kg (mix of fat, water, glycogen).
• Weeks 5–13 (VENTURE window) — Rate of weight loss may exceed tirzepatide's equivalent window per Viking's topline. Escalation steps each produce transient GI resurgence that resolves within days.
• Beyond 13 weeks (not yet characterized for VK2735) — Phase 3 program will define long-term curve, plateau timing, and maintenance.
• Discontinuation (class effect) — Weight regain is the consistent class pattern if no maintenance strategy replaces the pharmacotherapy.
• Non-responder pattern — Class-common at ~10% early non-response by 12 weeks. Early non-response predicts poor long-term response in class analogues.
• Red flags — Severe persistent vomiting, inability to tolerate fluids, severe abdominal pain, jaundice — clinical evaluation.

Practical User Notes

• Trial participation is the legitimate route — If interested in access, consult ClinicalTrials.gov for active Viking VK2735 studies and eligibility.
• Existing approved class options — Tirzepatide (Mounjaro / Zepbound) and semaglutide (Ozempic / Wegovy) are FDA-approved, insured, and accessible. For most patients seeking GIP/GLP-1 class therapy, these are the clinically appropriate paths.
• Research-chemical "VK2735" caveats — Identity cannot be community-verified. Product sold this way may or may not be the actual molecule from Viking's development program. Dose accuracy, purity, and stability are not regulated.
• If using research-chemical for self-experimentation — Third-party HPLC + mass spec COA from an independent lab is the minimum standard. Standard GIP/GLP-1-class monitoring (CMP, HbA1c, lipase if abdominal pain, DEXA body composition) applies.
• Slow titration is universally the tolerability strategy — No reason to expect faster is tolerable in VK2735 than in tirzepatide.
• Injection timing — Once weekly, consistent day. Many patients dose mornings after lighter dinner to minimize first-day nausea.
• Dose-day food strategy — Lighter meals (low-fat, high-protein, smaller volume) on injection day reduces nausea; universal class technique.
• Hydration — 2.5–3 L fluid during active titration. Dehydration amplifies every class adverse effect.
• Lean-mass preservation is the real project — VK2735 (like its class peers) does the weight loss; the user does the body-composition outcome through protein intake and resistance training.
• Red flags — Severe persistent vomiting, severe abdominal pain (especially radiating to back), jaundice, severe headache with visual change, hypersensitivity features, new persistent neck mass, unexpected severe hypoglycemia — immediate cessation and medical evaluation.

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Regulatory Status

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Next Steps

Key References

1. Viking Therapeutics. VK2735 Phase 2 (VENTURE) topline results: 13-week weight-loss data in adults with obesity. Press release and investor presentations, 2024.
2. Bays HE, Kelly AS, Aronne LJ, et al. Weekly subcutaneous VK2735 for weight management in adults with obesity — Phase 2 VENTURE trial. ObesityWeek 2024 / Obesity (Silver Spring). 2024.
3. Viking Therapeutics. Phase 1 pharmacokinetics, safety, and tolerability of subcutaneous VK2735 in healthy and obese volunteers. 2022–2023.
4. Viking Therapeutics. Phase 1 and Phase 2 oral VK2735 program: pharmacokinetics and early weight-loss signal. 2024–2025 communications.
5. ClinicalTrials.gov. A Study of VK2735 in Participants With Obesity (VENTURE). NCT05946356.
6. Coskun T, Sloop KW, Loghin C, Alsina-Fernandez J, Urva S, Bokvist KB, et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept. Mol Metab. 2018;18:3-14. PMID: 30473097.
7. Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al.; SURMOUNT-1 Investigators. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. PMID: 35658024.
8. Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S, Coskun T, Haupt A, Milicevic Z, Hartman ML; Retatrutide Phase 2 Obesity Trial Investigators. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. PMID: 37366315.
9. Rosenstock J, Frias J, Jastreboff AM, Du Y, Lou J, Gurbuz S, Thomas MK, Hartman ML, Haupt A, Milicevic Z, Coskun T. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. Lancet. 2023;402(10401):529-544. PMID: 37385275.
10. Frías JP, Davies MJ, Rosenstock J, Pérez Manghi FC, Fernández Landó L, Bergman BK, et al.; SURPASS-2 Investigators. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021;385(6):503-515. PMID: 34170647.
11. Wharton S, Astrup A, Endahl L, Lean MEJ, Satylganova A, Skovgaard D, Wadden TA. Oral semaglutide for the treatment of obesity. Lancet. 2023;402(10403):653-656. (Oral semaglutide class context.)
12. Viking Therapeutics. Corporate presentations and SEC filings, 2024–2026, detailing VK2735 Phase 2 data, oral formulation development, and anticipated Phase 3 timeline.
13. World Anti-Doping Agency. 2025 WADA Prohibited List. WADA, 2025.