Peptide-Drug Conjugates (PDCs) are targeted therapeutics that chemically link a biologically active drug (“payload”) to a peptide that guides the payload toward a specific receptor, microenvironment, or cellular compartment. Conceptually, PDCs resemble Antibody–Drug Conjugates (ADCs), but replace the antibody with a peptide, aiming to keep targeting precision while improving tissue penetration, manufacturing accessibility, and design flexibility. 1) What Exactly Is a PDC (and Why It Matters)? A typical PDC is built from three modular parts: Targeting peptide (the “homing” component) Linker (the chemical bridge that controls stability and payload release) Payload (cytotoxic drug, radionuclide, or other potent therapeutic) This modular architecture allows researchers to tune the PDC for: circulation stability, selective tissue uptake, cellular internalization, controlled release, and overall safety profile. Why it matters: modern drug discovery increasingly values precision delivery—getting more active agent to diseased tissue while reducing exposure to healthy tissue. PDCs are one of the main “next-generation” strategies being explored to push this idea further. 2) PDCs vs ADCs: Same Strategy, Different Vehicle Both PDCs and ADCs aim to deliver potent therapeutics using a targeting moiety + a linker + a payload. The difference is the targeting “vehicle”: ADCs: antibody-based targeting (large proteins)…
Molecular imaging is a family of techniques that visualizes biological processes in living subjects by using probes that bind to specific molecular targets. In nuclear medicine, PET (positron emission tomography) and SPECT (single-photon emission computed tomography) are workhorse modalities because they can detect tiny (trace) amounts of radiolabeled compounds and quantify target-related signals in vivo. Within PET/SPECT, targeted peptides have become a major probe class: short amino-acid sequences engineered to recognize receptors or other biomarkers (often overexpressed in tumors or diseased tissue), then “tagged” with a radionuclide so the binding event becomes imageable. 1) What Makes Peptide Targeting So Useful in PET and SPECT? Peptides sit in a sweet spot between small molecules and antibodies: High affinity and specificity (when well-designed): peptides can be tuned to fit receptor binding pockets or interaction surfaces, producing strong target-to-background contrast. Fast pharmacokinetics: many peptides clear from blood relatively quickly, which can reduce background signal and enable same-day imaging workflows (depending on isotope half-life and probe design). Chemically modular: it’s typically straightforward to add linkers, chelators, or stabilizing modifications without destroying binding—if the chemistry is placed away from the binding “hot spots.” In practice, peptide probes often target cell-surface receptors…
