Induced PD-L1 expression mediates acquired resistance to agonistic anti-CD40 treatment

Combination cancer immunotherapy and new immunomodulatory targets

Targeting immune checkpoints such as programmed cell death protein 1 (PD1), programmed cell death 1 ligand 1 (PDL1) and cytotoxic T lymphocyte antigen 4 (CTLA4) has achieved noteworthy benefit in multiple cancers by blocking immunoinhibitory signals and enabling patients to produce an effective antitumour response. Inhibitors of CTLA4, PD1 or PDL1 administered as single agents have resulted in durable tumour regression in some patients, and combinations of PD1 and CTLA4 inhibitors may enhance antitumour benefit. Numerous additional immunomodulatory pathways as well as inhibitory factors expressed or secreted by myeloid and stromal cells in the tumour microenvironment are potential targets for synergizing with immune checkpoint blockade. Given the breadth of potential targets in the immune system, critical questions to address include which combinations should move forward in development and which patients will benefit from these treatments. This Review discusses the leading drug targets that are expressed on tumour cells and in the tumour microenvironment that allow enhancement of the antitumour immune response.

Kick-starting the cancer-immunity cycle by targeting CD40

Stimulation of CD40 on dendritic cells to expand and activate tumor-specific T cells and generate anticancer immunity is an attractive therapeutic approach. Since CD40 agonists exert their effects upstream of checkpoint inhibitors, including PD-1 or PD-L1 antagonists, they are ideal candidates for combination regimens.