Petrelintide's Phase 3 Bet: Novel Amylin Mechanism Faces Tirzepatide's Shadow and Payer Skepticism

Zealand Pharma Initiates Registrational Phase 3 ZUPREME Program for Petrelintide

Zealand Pharma has initiated the global registrational Phase 3 ZUPREME program for petrelintide, a once-weekly amylin analog, targeting individuals with overweight or obesity. This program, conducted in collaboration with Roche, encompasses three trials—ZUPREME-3, ZUPREME-4, and ZUPREME-5—designed to enroll approximately 7,000 participants. These trials will assess petrelintide monotherapy against placebo across diverse patient populations, including those without type 2 diabetes, with type 2 diabetes, and with established cardiovascular disease. The Phase 3 initiation builds on positive Phase 2 results that demonstrated clinically meaningful double-digit weight loss and a favorable tolerability profile, aiming to establish petrelintide as a potential first-choice therapy for chronic weight management.

• The ZUPREME program is structured into three distinct Phase 3a trials to comprehensively evaluate petrelintide. ZUPREME-3 will enroll approximately 3,900 participants with overweight or obesity without type 2 diabetes. ZUPREME-4 will include about 600 participants with overweight or obesity and type 2 diabetes. ZUPREME-5 is designed for approximately 2,500 participants with overweight or obesity and established cardiovascular disease, with or without type 2 diabetes, ensuring broad assessment across relevant patient groups.
• The decision to advance petrelintide into Phase 3 is underpinned by compelling positive Phase 2 results. These earlier trials demonstrated clinically meaningful double-digit weight reduction, alongside a tolerability profile largely comparable to placebo. This strong clinical foundation supports petrelintide's potential for long-term adherence, which is crucial for effective chronic weight management, and positions it as a promising future first-choice therapy.
• Petrelintide is a long-acting amylin analog administered once-weekly via subcutaneous injection. Its mechanism involves activating amylin receptors, which helps restore sensitivity to the satiety hormone leptin and induces a feeling of fullness faster, thereby reducing body weight. Furthermore, Zealand Pharma and Roche are planning to initiate a Phase 2 trial in the second half of 2026 to explore petrelintide in combination with Roche’s GLP-1/GIP receptor dual agonist, enicepatide (CT-388).

Addressing the Unmet Needs in Chronic Weight Management

Chronic weight management remains one of the most complex therapeutic challenges in modern medicine, with no single intervention offering a complete solution across efficacy, safety, and long-term durability. Current approaches — spanning pharmacotherapy, surgical intervention, and lifestyle modification — each carry distinct limitations that constrain their real-world effectiveness.

• Gastrointestinal tolerability of anti-obesity pharmacotherapies: GLP-1 receptor agonists such as semaglutide and tirzepatide, while highly effective for weight reduction, are associated with frequent gastrointestinal adverse events including nausea, vomiting, diarrhea, and constipation — particularly during dose escalation. In a meta-analysis of semaglutide in non-diabetic adults, treatment discontinuation due to adverse events was significantly higher in the semaglutide group (RR 2.62; 95% CI: 1.70–4.03; P = .001). For tirzepatide, serious GI events and discontinuation due to adverse events carried relative risks of 3.07 (95% CI: 2.03–4.66) and 2.29 (95% CI: 1.74–3.01), respectively.

• Loss of lean mass during pharmacological weight loss: Incretin-based therapies — including liraglutide, semaglutide, tirzepatide, and retatrutide — induce approximately 15–24% weight loss but also cause rapid and significant loss of lean mass (~10% or ~6 kg), comparable to a decade or more of aging. This lean mass reduction may contribute to difficulties in maintaining weight over the long term and can lead to sarcopenia, a condition strongly linked to morbidity and mortality.

• Long-term nutritional and metabolic complications of bariatric surgery: Bariatric surgery delivers substantial and sustained weight loss, with gastric bypass and sleeve gastrectomy associated with significant improvements in comorbidities such as type 2 diabetes and hypertension. However, long-term complications — including nutritional deficiencies, risk of anaemia, bone fracture, neurological and psychological complications, and the need for reoperations — remain persistent challenges. Adherence to long-term follow-up has been shown to decrease over time, limiting the ability to monitor and manage these risks.

• Malabsorption and the need for surgical revision: Procedures such as single anastomosis duodenoileal bypass with sleeve gastrectomy (SADI-S) carry a risk of severe malabsorption, including protein-calorie malnutrition and nutritional deficiencies, necessitating conversion to less malabsorptive procedures. While laparoscopic conversion to alternatives such as single anastomosis duodenojejunal bypass with sleeve gastrectomy (SADJ-S) or gastric bypass resolved malabsorptive symptoms in reported cases, weight regain was a universal consequence, with a mean BMI increase of 7.1 kg/m².

• Age-related biological mechanisms undermining treatment response: MC4R-bearing primary cilia of hypothalamic neurons progressively shorten with age, impairing neuronal sensitivity to melanocortin and resulting in decreased brown fat thermogenesis, reduced energy expenditure, increased appetite, and ultimately obesity and leptin resistance. This age-related ciliopathy represents a biological barrier to sustained treatment efficacy that current pharmacological and surgical approaches do not directly address.

• Uncertainty in long-term safety and durability of emerging agents: Natural products and investigational anti-obesity agents report fewer adverse events but lack long-term data and standardized reporting. Evidence across the pharmacotherapy landscape is further limited by heterogeneity in study design and inconsistent reporting of outcomes, leaving the long-term GI safety profiles and durability of weight loss for newer agents such as retatrutide and orforglipron insufficiently characterized.

Deep Dive into the Petrelintide ZUPREME Phase 3 Program

Two pivotal randomized controlled trials evaluated pharmacological interventions for overweight and obesity, each employing rigorous double-blind, placebo-controlled designs with weight-based co-primary endpoints assessed over multi-week treatment periods.

Petrelintide's Role in Emerging Combination Strategies for Obesity

The most clinically advanced combination approach under investigation pairs semaglutide, a GLP-1 receptor agonist, with cagrilintide, a long-acting amylin analogue, for once-weekly administration — a regimen currently in Phase 3 development. Beyond this, the broader pipeline has moved toward multi-receptor agonism as a foundational strategy: tirzepatide, a dual GIP/GLP-1 receptor agonist, has induced weight loss of approximately 20% in people with obesity without diabetes, while the triple agonist retatrutide — targeting GIP, GLP-1, and glucagon receptors simultaneously — has demonstrated a maximum weight reduction effect of 22.6 kg in model-based analyses and 15.3% bodyweight reduction at the 12 mg dose in a Phase 3 trial at 40 weeks. Several non-peptide small molecule GLP-1 agonists for oral administration are also in late-stage development, broadening the modality landscape beyond injectable agents.

A systematic review and meta-analysis of 10 randomized controlled trials encompassing 3,236 participants evaluated tirzepatide, retatrutide, and mazdutide, finding that incretin polyagonists significantly reduced body weight compared to placebo (MD -11.47; 95% CI: -14.00 to -8.95), with additional reductions in waist circumference (MD -9.40; 95% CI: -11.91 to -6.89), glycated hemoglobin (MD -0.96; 95% CI: -1.16 to -0.75), and fasting plasma glucose (MD -26.89 mg/dL; 95% CI: -33.48 to -20.30). A model-based meta-analysis of 55 studies further quantified the incremental benefit of receptor breadth: at 52 weeks, weight reduction effects were 7.03 kg, 11.07 kg, and 24.15 kg for mono-agonists, dual-agonists, and tri-agonists, respectively, with a significant negative correlation between age and weight reduction effect.

The safety profile of these combination and multi-agonist approaches is characterized predominantly by gastrointestinal adverse events — nausea, vomiting, diarrhea, and constipation — which are generally mild to moderate and subside over time with slow up-titration. The meta-analysis confirmed a higher risk of any adverse events (RR 1.13; 95% CI: 1.08–1.19), adverse events leading to withdrawal (RR 1.96; 95% CI: 1.17–3.30), and hypoglycemic episodes (RR 3.08; 95% CI: 1.61–5.89) with dual and triple agonists versus placebo, though no significant difference was observed in serious adverse events (RR 0.87; 95% CI: 0.65–1.14). Rare but clinically significant complications, such as ischemic colitis, have also been reported in association with incretin-based therapies, underscoring the importance of ongoing pharmacovigilance as these agents advance.

Petrelintide's Phase 3 Launch: A New Era for Amylin Analogs?

The launch of Zealand Pharma's ZUPREME Phase 3 program for petrelintide signals a significant escalation in the pursuit of more effective and tolerable treatments for chronic weight management. As a once-weekly amylin analog, specifically a dual amylin and calcitonin receptor agonist (DACRA), petrelintide targets key physiological pathways involved in appetite regulation, gastric emptying, and glucagon secretion. This multi-pronged approach is designed to address the complex biological underpinnings of obesity, moving beyond a singular focus on energy restriction.

The ambition to position petrelintide as a 'first-choice therapy' is underscored by the expansive Phase 3 program, which will enroll approximately 7,000 participants across a spectrum of patient profiles, including those without type 2 diabetes, with type 2 diabetes, and with established cardiovascular disease. This broad targeting strategy aims to secure a comprehensive label, reflecting the diverse needs of individuals living with obesity and its associated comorbidities. The collaboration with Roche further amplifies the strategic intent, providing substantial resources and global reach to support this ambitious undertaking.

However, the path to market leadership is not without its challenges. The literature indicates that amylin analogs, much like GLP-1 receptor agonists, can be associated with gastrointestinal side effects, particularly nausea, which may affect patient adherence. Furthermore, the obesity treatment landscape is rapidly evolving and highly competitive, with numerous established and emerging therapies, including other long-acting amylin analogs and multi-agonists, vying for market share. While petrelintide's mechanism offers a promising avenue for clinically meaningful weight loss, demonstrating definite disease-modifying action beyond weight reduction will be critical for long-term differentiation and value in this chronic condition. The success of the ZUPREME program will therefore hinge on not only robust efficacy but also a compelling tolerability profile and clear advantages over existing and pipeline competitors.