CTLA4 and cancer: The serum levels of TNF-α and IFN-γ were significantly increased in the mice treated with PLGA-ICG-R837-based PTT, particularly for those with PTT plus the second round of anti-CTLA-4 treatment (post), indicating the successful establishment of anti-tumour immune responses triggered by the rechallenging of cancer cells 40 days later in this group (Fig. 5d,e).