M2 tumor-associated macrophages (via M2-binding peptide); mitochondrial membrane (via dKLA payload)

Class

Peptide-drug conjugate (M2-macrophage-targeting peptide conjugated to a pro-apoptotic dKLA peptide)

Pathway

Selective depletion of immunosuppressive M2 macrophages via mitochondrial membrane disruption and apoptosis

This mechanism targets tumor-associated macrophages (TAMs) polarized into the M2 phenotype, a state associated with tissue repair and immune suppression rather than active defense against pathogens or abnormal cells. Within tumors, M2-skewed macrophages secrete factors that dampen anti-tumor immune responses, support blood vessel growth, and facilitate invasion and metastasis, making them a significant contributor to an immunosuppressive tumor microenvironment. Rather than trying to reprogram these cells toward an anti-tumor state, this approach uses a peptide-drug conjugate: a targeting peptide that recognizes surface markers preferentially found on M2 macrophages is chemically linked to a second peptide, dKLA, which disrupts mitochondrial membranes once inside a cell. When the conjugate binds M2 macrophages and is internalized, the payload triggers mitochondrial membrane breakdown, releasing pro-apoptotic factors and driving the cell into programmed death. The intended result is selective depletion of the immunosuppressive macrophage population, reducing its tumor-supportive signaling and potentially making the tumor more accessible to other immune-based therapies. This strategy sits within the broader field of tumor microenvironment remodeling, an area of interest across many solid tumor types where macrophage-driven immune evasion limits the effectiveness of other treatments.