Pyridine-containing antitumor agents: structure-oriented medicinal chemistry, structure-activity relationships, and ADMET liabilities.

Pyridine is a common nitrogen-containing heteroaromatic motif in antitumor medicinal chemistry, but its design value is highly context dependent. Here, we synthesize structure-oriented medicinal chemistry principles that govern the use of pyridine-related motifs in antitumor drug design. We discuss pyridine-containing antitumor agents with emphasis on target recognition, scaffold organization, structure-activity relationship (SAR), drug metabolism and pharmacokinetics (DMPK), and absorption, distribution, metabolism, excretion, and toxicity (ADMET) liabilities. Representative approved drugs, antibody-drug conjugate (ADC) payloads, targeted degraders, and polypyridyl metal complexes are used to illustrate how pyridine-related motifs can support binding, property tuning, and modality adaptation. By grouping representative compounds according to the medicinal chemistry function of their pyridine-related motifs, this review provides a practical framework for future scaffold design. Overall, pyridine should not be viewed as a universally beneficial privileged scaffold; it is better treated as a context-dependent design module that requires validation through integrated structural, SAR, ADMET, and translational evidence.