GUBamy: Molecular Structure

Molecular Structure#

GUBamy (GUB014295) is a synthetic peptide engineered as a long-acting dual amylin and calcitonin receptor agonist (DACRA). While the detailed amino acid sequence has not been publicly disclosed by Gubra, the key design principles and pharmacological characteristics are known from published data.

Design Context#

GUBamy builds on decades of research into amylin analogs and DACRAs:

Native amylin (IAPP):

• 37-amino acid peptide hormone
• Co-secreted with insulin from pancreatic beta cells
• Half-life of approximately 15 minutes (impractical for therapeutic use)
• Prone to aggregation and amyloid fibril formation (the defining pathology of type 2 diabetes islet amyloid)

Pramlintide (approved amylin analog):

• Three amino acid substitutions (Pro25, Pro28, Pro29) to reduce aggregation
• Retains short half-life requiring thrice-daily injection
• Limited clinical adoption due to dosing burden

GUBamy (next-generation DACRA):

• Engineered for dramatically extended half-life (11 days)
• Activates both amylin and calcitonin receptors
• Supports once-weekly subcutaneous dosing
• Designed to overcome the practical limitations that limited pramlintide adoption

Chemical Properties#

Pharmacokinetics#

GUBamy's pharmacokinetic profile was characterized in the phase 1 SAD study:

• Half-life: Approximately 270 hours (11 days), confirmed by pharmacokinetic analysis
• Dose proportionality: Demonstrated across the dose range studied
• Absorption: Subcutaneous injection with sustained absorption kinetics
• Steady state: Expected to be achieved within 2-3 weekly doses based on the 11-day half-life
• Accumulation: Moderate accumulation expected with weekly dosing (half-life > dosing interval)

Half-Life Comparison with Other Amylin Analogs#

The 11-day half-life of GUBamy is among the longest of any amylin-class agent in development, providing substantial overlap between weekly doses and ensuring consistent receptor activation.

Receptor Binding Profile#

GUBamy is classified as a DACRA because it activates both:

Amylin Receptors (AMY1, AMY2, AMY3)#

Amylin receptors are heterodimeric complexes formed by the calcitonin receptor (CTR) paired with receptor activity-modifying proteins (RAMPs):

• AMY1: CTR + RAMP1
• AMY2: CTR + RAMP2
• AMY3: CTR + RAMP3

Activation of these receptors mediates appetite suppression, gastric emptying delay, and glucagon suppression.

Calcitonin Receptor (CTR)#

Direct activation of the calcitonin receptor (without RAMPs) mediates additional effects on energy metabolism and potentially bone turnover. The relative contribution of CTR agonism to the metabolic effects of GUBamy versus amylin receptor agonism alone is an area of ongoing research.

Stability#

The specific modifications enabling GUBamy's extended half-life have not been fully disclosed. Common approaches for extending peptide half-life include:

• Fatty acid acylation (used by semaglutide, liraglutide, cagrilintide)
• PEGylation
• Fc fusion
• Amino acid substitutions to resist proteolysis
• Albumin binding modifications

The exact strategy used for GUBamy has not been publicly confirmed.

Related Reading#

• GUBamy overview and research guide
• Peptides similar to GUBamy
• GUBamy research evidence