In the real world, the selection of a therapeutic modality like an antibody or peptide is often driven by a company's existing expertise and technology platform rather than a purely agnostic approach to finding the single best tool for a clinical problem. Organizations default to the tools in their toolbox.

Breakthrough drugs aren't always driven by novel biological targets. Major successes like Humira or GLP-1s often succeeded through a superior modality (a humanized antibody) or a contrarian bet on a market (obesity). This shows that business and technical execution can be more critical than being the first to discover a biological mechanism.

The industry's focus on antibodies, which are easy to generate, may be a case of technology dictating the science. Dr. Radvanyi argues that natural ligand-receptor interactions, which often rely on lower affinity and higher avidity, could offer a more nuanced and effective way to modulate immune pathways than high-affinity agonist antibodies.

The debate isn't about peptides replacing antibodies but about combining them. The future lies in hybrid therapeutics, such as grafting peptides into antibody CDRs or creating fusions that use a peptide for optimal target binding and an antibody scaffold for effector functions, half-life extension, and stability.

While GLP-1 has been a known target for a long time, the recent explosion in peptide therapeutics was primarily enabled by solving the historical challenge of poor half-life and exposure. Achieving one- or two-week half-lives through techniques like fatty acid acylation was the critical technological unlock for the field.

Tirzepatide is a rare "once in a blue moon" drug because it is both more potent and better tolerated than its main competitor. This paradoxical profile—achieving superior efficacy with fewer side effects—has established it as the "king of the hill" in the obesity market and created an extremely high bar for any challenger.

The FDA defines a peptide as an amino acid chain of 40 or less. Blockbuster drugs like Ozempic and Mounjaro are all exactly 39 amino acids long. This perfect fit suggests potential regulatory shaping or clever drug design to fit an advantageous classification.

Acknowledging its late entry into the crowded obesity market, Protagonist consulted key opinion leaders to define the ideal drug profile: an oral "triple G" agonist. By using its peptide platform to build exactly what experts requested, the company aims to leapfrog competitors with a best-in-class product rather than an incremental improvement.

CEO Jonathan Steckbeck simplifies a complex topic by describing peptides as a "Goldilocks modality." They sit between small molecules (good access, poor specificity) and biologics (poor access, good specificity), ideally offering the best of both worlds for targeted drug delivery.