By Karsten Eastman, PhD | September 30, 2026
Peptide discovery is entering an era of abundance. Researchers can build larger libraries, incorporate noncanonical residues, constrain backbones in multiple ways, and use increasingly capable computational tools to propose or rank candidates. Yet many programs still organize discovery around a narrow objective: identify the strongest binder.
Affinity is important, but it is not a drug profile. A peptide must also be selective, soluble, synthetically tractable, sufficiently stable, and able to reach the relevant biological compartment. Depending on the program, it may need to cross a membrane, remain extracellular, internalize into a specific cell type, or sustain activity after transient exposure. A screen that reports only binding leaves these questions for later, when changing molecular direction is more expensive.