Description of Medical ServicePD-L1 is expressed on tumour cells in a broad range of cancer types, including lung cancer. PD-L1 aids cancers in evading detection and elimination by the immune system by supressing the anti-tumour T cell response. Anti-PD-L1 antibodies can be used therapeutically to enhance anti-tumour immune responses in patients with cancer.
IMFINZI™ (durvalumab, MEDI4736) is a human monoclonal antibody that inhibits binding of PD-L1 to programmed cell death receptor 1 (PD-1). Durvalumab prevents PD-L1 from interacting with its receptors, thus relieving its immunosuppressive effects and enhancing the cytotoxic activity of anti-tumour T cells. Tremelimumab (MEDI1123) is a human monoclonal antibody of the IgG2 kappa subclass which specifically binds to cytotoxic T-lymphocyte antigen -4 (CTLA-4). Upon binding to one of the B7 ligands (CD86 or CD80), CTLA-4 inhibits T cell activity during the early stages of T cell activation. Tremelimumab blocks CTLA-4, prolonging T cell activation and proliferation and enhancing T cell anti-tumour activity. Targeting both the PD-1 and CTLA-4 pathways may have additive or synergistic activity because the mechanisms of action of the PD-1 and CTLA-4 pathways are non-redundant.
The level of PD-L1 gene expression can be assessed using immunohistochemical (IHC) testing with antibodies that bind specifically to the PD-L1 expressed on tumour cells. Several commercial PD-L1 testing kits are now available in Australia. PD-L1 testing is also being conducted to support cancer clinical trials or for research purposes at pathology laboratories in major cancer research hospitals/institutions in Australia.
This application is a co-dependent request for MBS listing of PD-L1 testing to determine which advanced or metastatic NSCLC patients have a high level of PD-L1 gene expression (defined as PD-L1 ≥25%) in order to qualify for requested PBS access to 1st line durvalumab monotherapy treatment, and which advanced or metastatic NSCLC patients have a low level of PD-L1 gene expression (defined as PD-L1 <25%) in order to qualify for requested PBS access to 1st line durvalumab/tremelimumab combination treatment.