When BoNT/A (25 pg μl−1, 50 μl, five i.d. sites) was administered one and three days before the B16F10-OVA cell inoculation, it reduced subsequent tumour growth and preserved the cytotoxic potential of intratumoral CD8+ T cells (Extended Data Fig. 7g–n; as measured 18 days after inoculation). Here, CD8A is linked to neoplasm.