Despite ongoing progress in Antibody-Drug Conjugates (ADCs) therapy, several challenges remain. For instance, the complex structure of ADCs leads to high production costs and a long half-life, which increases systemic toxicity due to prolonged exposure in the plasma. Consequently, Peptide-Drug Conjugates (PDCs) have emerged as a promising alternative. PDCs consist of three components: a homing peptide, a linker, and a payload drug. Utilizing the high affinity of homing peptides for tumor surface receptors, PDCs deliver the payload drug directly to the target.
Peptide-Drug Conjugates (PDCs) have emerged as a promising targeted therapeutic platform that addresses several limitations of Antibody-Drug Conjugates (ADCs), including their large molecular size, prolonged circulation, and high manufacturing costs. Composed of a targeting peptide, a linker, and a therapeutic payload, PDCs can selectively deliver a wide range of agents-including chemotherapeutics, radionuclides, proteins, and nucleic acids-to disease sites. Their smaller size, improved tissue penetration, lower immunogenicity, and simplified production process make them an attractive next-generation modality for targeted drug delivery.
The pharmacokinetic behavior of PDCs is largely determined by the intrinsic properties of peptide molecules. Most PDCs are administered intravenously because peptides exhibit poor oral bioavailability and are rapidly degraded in the gastrointestinal tract. After administration, PDCs undergo receptor-mediated targeting and cellular uptake but also face challenges such as rapid proteolytic degradation, renal clearance, and potential off-target payload release. Their metabolism involves target-mediated drug disposition (TMDD), non-specific proteolysis, and, in some cases, immunogenic responses that may generate anti-drug antibodies (ADAs), all of which influence drug exposure, efficacy, and safety.
Effective pharmacokinetic evaluation is essential for optimizing PDC development. During early discovery, DMPK studies should focus on improving peptide stability, extending half-life, characterizing metabolites, and assessing tissue distribution to minimize off-target toxicity. At the clinical candidate stage, both intact PDCs and released payloads should be quantitatively monitored in vivo, while repeated-dose studies should evaluate ADA formation and tissue targeting efficiency. Although challenges such as peptide instability, limited targeting specificity, and analytical complexity remain, continued advances in peptide engineering and conjugation technologies are expected to accelerate the development of PDCs as an important class of targeted therapeutics.
Conclusion and Outlook
The design of PDC drugs integrates the advantages of targeting peptides and various types of drugs. Recent regulatory approvals of radionuclide therapeutic drugs and diagnostic agents highlight the potential of these drugs. Encouraging clinical results from ongoing clinical pipelines further underscore their promise. With the conjugation of various molecular entities and targeting peptides, the development of PDC drugs holds great potential for the future.
