In a colon adenocarcinoma mouse model, Maxwell et al. observed that only 1 out of 8 anti-PD-1 plus dexamethasone treated mice had a complete response compared to 4/8 mice treated with anti-PD-1 alone with an increased tumour growth rate in the anti-PD-1 plus dexamethasone group35. The gene discussed is PDCD1; the disease is colon adenocarcinoma.