Laura Codarri Deak

Our immune system is a complex and finely tuned fighting force, primed to recognise pathological cells or microorganisms in our body that don’t belong and destroy them. Tapping into these natural defenders — and training them to act against tumour cells — is the idea behind cancer immunotherapy. Unfortunately, cancer immunotherapy does not yet work for everyone — sometimes, it does not effectively fight tumours, and sometimes, it causes the immune system to dangerously overreact.

Abstract Expansion and differentiation of antigen-experienced PD-1+TCF-1+ stem-like CD8+ T cells into effector cells is critical for the success of immunotherapies based on PD-1 blockade1,2,3,4. Hashimoto et al. have shown that, in chronic infections, administration of the cytokine interleukin (IL)-2 triggers an alternative differentiation path of stem-like T cells towards a distinct population of ‘better effector’ CD8+ T cells similar to those generated in an acute infection5.