In addition to carrying small-molecule drugs and photothermal responsive elements for chemotherapy and photothermal therapy in cancer, microneedles can also carry biologically active drugs such as therapeutic immune checkpoint inhibitors (e.g., anti-CTLA-4 and anti-PD-1/PD-L1 antibodies) and CAR-T cells for cancer treatment through immunotherapy [125]. Here, CTLA4 is linked to cancer.