In our experiments, mice post spreading of 4T1 tumour cells (i.v. injection) with surgical removal of their primary tumours and treated with the combination of CTLA-4 and PD-L1 co-blockade, or even together with the treatment of PLGA-ICG-R837 but no laser irradiation, showed obvious cancer metastases as indicated by bioluminescence imaging (Supplementary Fig. 10). Here, CTLA4 is linked to cancer.