BTLA and small cell lung carcinoma: A fairly limited number of patients (67) with advanced non-small cell lung cancer (NSCLC) or with refractory extensive-stage small cell lung cancer (SCLC) were enrolled for phase I/II of a clinical trial of Tifcemalimab (a recombinant humanized IgG4k monoclonal antibody targeting BTLA) combined with Toripalimab, a therapeutic monoclonal anti-PD-1 antibody with high binding affinity to PD-1 and enhanced potency to activate human T cells [109].