Notably, specific in vivo stimulation of o9R signalling in TCR- and CAR-based tumour-specific T cells by the orthogonal IL-2 ligand 3A10 results in improved anti-tumour activity in two solid tumour models that are refractory to immunotherapy, and retains robust activity in a more stringent setting without conditioning lymphodepletion. The gene discussed is IL2; the disease is neoplasm.