CTLA4 and non-small cell lung carcinoma: In melanoma, it has been shown that anti‐CTLA4 antibody treatment initially reduces tumour burden, but the resistant cancer cells have increased PD‐L1 expression.16 We found that anti‐CTLA4 antibody, when present in the culture media, increased PD‐L1 expression in NSCLC cell lines (Figure 2A).