Multiple indirect physiological targets via paracrine signaling and cell-cell interactions

This entry does not represent a single molecular target but rather a complex mechanism of action involving multiple indirect physiological pathways. It is frequently used to categorize therapeutic agents, such as cell-based therapies (e.g., mesenchymal stem cells), that do not bind to a single receptor but instead exert their effects through the secretion of various paracrine factors and direct cell-cell interactions (Galipeau & Sensébé, 2018). These interactions can modulate the immune system, promote tissue repair, and influence the local microenvironment through a combination of cytokines, growth factors, and extracellular vesicles (Alberts et al., 2002). Because the therapeutic outcome is the result of a coordinated response across multiple signaling networks, identifying a single canonical target is not scientifically accurate. This classification is often found in pharmacological databases to describe drugs with pleiotropic effects where the exact molecular stoichiometry is undefined. Consequently, traditional drug-target interaction models are insufficient to describe the pharmacodynamics of such agents. Safety concerns often involve the unpredictable nature of systemic paracrine effects and the potential for immunogenicity (Pittenger et al., 2019). Biomarkers for such targets typically involve systemic inflammatory markers or specific cell-surface proteins rather than target occupancy assays. This category highlights the shift in modern pharmacology toward systems-biology-based therapeutic interventions. Overall, it serves as a placeholder for agents whose primary mode of action is intercellular rather than intracellular or receptor-mediated.

Other names

Paracrine signalingCell-cell interactionIndirect physiological targetsNon-specific cellular targets

Therapeutic effect is mediated through the secretion of a complex mixture of paracrine factors and direct cell-to-cell contact rather than a single molecular target.