Beyond PD-L1 Markers for Lung Cancer Immunotherapy

Abstract

Immunotherapy using immune checkpoints inhibitors has become the standard treatment for first and second line therapy in patients with non-small cell lung cancer (NSCLC). However, proper predictive factors allowing precise qualification of NSCLC patients for immunotherapy have not been developed so far. Expression of PD-L1 on tumor cells and tumor mutation burden are used in qualification of patients to first line therapy with pembrolizumab and atezolizumab in combination with ipilimumab in prospective clinical trials. Nevertheless, not all patients with these predictive factors benefit from immunotherapy. Major methodological difficulties in testing of these factors and in the interpretation of test results still exist. Therefore, other predictive factors are sought. Intensive research on the recognition of tumor immunophenotype and gut microbiome in NSCLC patients are underway. The first correlations between the effectiveness of immunotherapy and the intensity of inflammatory response in the tumor, microbiome diversity, and the occurrence of certain bacterial species in gut have been described. The purpose of our manuscript is to draw attention to factors affecting the efficacy of immunotherapy with anti-PD-L1 antibodies in NSCLC patients. Additional markers, for example TMB (tumor mutations burden) or microbiome profile, are needed to more accurately determine which patients will benefit from immunotherapy treatment.

Keywords: NSCLC; PD-1; PD-L1; immune-check points inhibitors; microbiome; tumor immunophenotype; tumor mutation burden.

Figure 1

Mechanisms of: killing tumor cells by active T lymphocytes (A); blocking their action through the interaction of PD-1 and PD-L1 molecules (B); and re-activation of T-cell activity by using anti-PD-1 or anti-PD-L1 antibodies (C).

Figure 2

General scheme of microbiome disorders associated with cancer.