Emerging peptide · Mid-stage emerging

PYY 3-36 long-acting analogs

Engineered PYY analogs targeting the appetite-regulation pathway alongside GLP-1.

Phase 1/2

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This section covers peptides at the frontier of research. Most entries are preclinical, in early or mid-stage clinical trials, or theoretical. Evidence levels are explicitly marked on every entry.

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At a glance

Novo Nordisk and others are developing long-acting PYY 3-36 analogs that hit a different limb of the appetite-regulation system than GLP-1. Combination with GLP-1 agents is one of the active research questions.

Class
Peptide YY (PYY 3-36) analogs
Sponsor
Novo Nordisk; multiple academic / industry programs
Stage
Phase 1-2 (depending on candidate)
Lead use case
Obesity (often as combination with GLP-1)

What it is

Peptide YY (PYY) is a gut hormone produced primarily by L-cells in the distal small intestine and colon, with PYY 3-36 (the active form after dipeptidyl peptidase IV cleavage) acting on Y2 receptors in the brainstem and hypothalamus to suppress appetite. Long-acting PYY analogs are being developed to leverage this distinct appetite-regulation pathway.

Current research status

Several Phase 1 and Phase 2 programs from Novo Nordisk and academic groups have explored long-acting PYY analogs, often in combination with GLP-1 agonists. Native PYY 3-36 has a very short half-life (~10 minutes), so engineering for clinically relevant duration is the central pharmaceutical challenge.

Mechanistic rationale

PYY 3-36 binds the Y2 receptor on appetite-regulating neurons in the arcuate nucleus and brainstem, suppressing food intake through a pathway distinct from GLP-1 but partially overlapping in downstream effects. Native PYY 3-36 is released after meals and contributes to post-prandial satiety; long-acting analogs are designed to amplify and sustain that satiety signal.

Available evidence

Native PYY 3-36 administration has been shown to reduce caloric intake in human studies dating back to the 2000s. Long-acting analogs in current development have shown appetite-suppression and modest weight-loss effects in early-phase trials, with a tolerability profile that includes substantial nausea at higher doses.[1]

Why it's interesting

The Y2 receptor pathway is mechanistically distinct from GLP-1 / GIP / glucagon. If a PYY analog can be engineered for once-weekly dosing without the nausea profile that has limited earlier work, it could provide a third therapeutic axis for combination therapy alongside the incretin and amylin classes. The combination potential is part of why the pharmaceutical interest persists despite earlier-program difficulties.

Limitations & risks

PYY 3-36 produces nausea reliably enough that it has been one of the historical tolerability bottlenecks for the class. Whether engineering can preserve appetite suppression while reducing nausea is the central pharmaceutical challenge. The bariatric-surgery literature suggesting endogenous PYY contributes to post-surgical weight loss provides mechanistic motivation; converting that into a dosed therapy has been harder than the gut-hormone biology suggested.

Community discussion notes

Less broadly discussed than the lead incretin candidates, but tracked by metabolic-medicine specialists as part of the next-generation combination-therapy landscape. Mechanistic interest exceeds the current evidence base.

The takeaway

Long-acting PYY analogs are a genuinely interesting therapeutic concept that has had a more difficult development path than the underlying biology suggested it would. Phase 2 readouts from the current programs will determine whether the class advances into combination-therapy regimens or remains a research target.

References

  1. Karra E, Chandarana K, Batterham RL. The role of peptide YY in appetite regulation and obesity. J Physiol. 2009;587(1):19-25. https://pubmed.ncbi.nlm.nih.gov/19064614/
  2. Tan T, et al. Peptide YY 3-36 reduces appetite in healthy adults. N Engl J Med. 2003;349(10):941-948. https://pubmed.ncbi.nlm.nih.gov/?term=PYY+3-36+appetite