Anti-programmed cell death 1 (PD-1) antibodies have antitumor activity in this disease, but little is known about the activity of anti-programmed cell death ligand 1 (PD-L1) antibodies in patients with mesothelioma.
Medline search used keywords 'mesothelioma' combined with 'checkpoint blockade' OR 'PD-L1' OR 'PD1' OR 'anti-CTLA4'; the search terms AND 'clinical trial' or AND 'biomarker*' were added.
<b>Purpose:</b> Mesothelioma has been regarded as a nonimmunogenic tumor, which is also shown by the low response rates to treatments targeting the PD-1/PD-L1 axis.
Studies utilizing single-agent PD-1 or PD-L1 inhibitor for mesothelioma have reported tumor response rates in approximately 10-20% of patients treated.
Early promising signals of activity relating to both PD-L1- and PD-1-targeted treatment in mesothelioma implicate a dependency of mesothelioma on this immune checkpoint.
In this study, 175 well-characterized primary diffuse pleural mesotheliomas, including the epithelioid (n = 148), biphasic (n = 15), and sarcomatoid (n = 12) histotypes, were evaluated immunohistochemically for cancer stem cell markers (ALCAM, ALDH1, and SALL4) and PD-L1 expression.
Antibody-dependent cellular cytotoxicity (ADCC) of avelumab, a fully humanized immunoglobulin G1 anti PD-L1 antibody against primary mesothelioma cell lines, was evaluated in presence of autologous and allogeneic natural killer cells.