Table 1

Target molecules/mechanism of action and current indications for ICIs6–11

TargetFunction of targeted checkpointImmune checkpoint inhibitorFDA-approved tumour type*
CTLA-4

  • Expressed on: T-cells

  • Mechanism: inhibits T-cells after initial activation

  • Active in: lymph nodes

Ipilimumab
(Yervoy)

  • Melanoma

  • RCC

  • MSI-H/dMMR colorectal cancer

PD-1

  • Expressed on: various immune cells

  • Mechanism: binds to PD-L1 and PD-L2 on tumour or immune cells to inhibit T-cell activity

  • Active in: peripheral tissues with pre-existing inflammation

Nivolumab
(Opdivo)
Pembrolizumab (Keytruda)

  • Melanoma

  • SCCHN

  • UC

  • NSCLC

  • SCLC

  • MSI-H/dMMR cancers, including colorectal cancer

  • Hodgkin’s lymphoma

  • RCC

  • HCC

  • Cervical cancer

  • Primary mediastinal large B-cell lymphoma

  • Merkel cell carcinoma

PD-L1

  • Expressed on: various immune cells and tumour cells

  • Mechanism: binds to PD-1 and CD80 on T-cells and inhibits T-cell proliferation

  • Active in: peripheral tissues

Atezolizumab
(Tecentriq)
Durvalumab
(Imfinzi)

  • NSCLC

  • UC

Avelumab
(Bavencio)

  • Merkel cell carcinoma

  • UC

  • *ICIs are FDA-approved for certain subtypes of patients with these tumour types.

  • CTLA-4, cytotoxic T-lymphocyte antigen-4; dMMR, mismatch repair deficient; FDA, US Food and Drug Administration; HCC, hepatocellular carcinoma; ICI, immune checkpoint inhibitor; MSI-H, microsatellite instability-high; NSCLC, non-small cell lung cancer; PD-1, programmed death-1; PD-L1, programmed death ligand 1; PD-L2, programmed death ligand 2; RCC, renal cell carcinoma; SCCHN, squamous cell carcinoma of the head and neck; SCLC, small cell lung cancer; UC, urothelial carcinoma.