The present disclosure relates to compositions and methods comprising peptide molecules that mimic the binding and functional properties of native antibodies relative to their respective targets. Some embodiments comprise peptide-drug conjugates (PDCs) comprising the mimic peptides disclosed herein. The targets of these mimic peptides include epidermal growth factor receptor (EGFR), and human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor (VEGF), programmed cell death protein 1 (PD-1), and programmed death-ligand 1 (PD-L1). The present disclosure comprises application of the knob-socket computational model to design antibody mimics for proteins.