Abstract: Described herein are peptides and variants thereof as well as peptide constructs comprising peptides conjugated to, linked to, or fused to agents, wherein the peptides and peptide constructs are capable of binding TfR. Binding of a peptide or peptide construct as described herein to TfR can enable transcytosis across an endothelial layer, e.g., the blood brain barrier, or the crossing of a cell membrane. Pharmaceutical compositions and uses of peptides and peptide constructs, as well as methods of designing and manufacturing such peptides and peptide constructs, to treat a disease or condition are also described herein.

Abstract: Compositions such as pharmaceutical compositions and uses for peptide-drug conjugates are disclosed. Such compositions can deliver a drug, a peptide, or a conjugate thereof to a target region, tissue, structure or cell in cartilage.

Abstract: Peptides that home, migrate to, distribute to, accumulate in, are directed to, and/or bind to tumors, cancerous tissues and cells thereof are disclosed. Pharmaceutical compositions and uses for peptides, peptide-active agent complexes comprising such peptides, or peptide-detectable agent complexes comprising such peptides are additionally disclosed. Such compositions can be formulated for targeted or untargeted delivery of a drug to a target region, tissue, structure or cell. Targeted compositions of the disclosure can deliver peptide, peptide-active agent complexes, or peptide-detectable agent complexes to target regions, tissues, structures or cells targeted by the peptide.