Previous investigations have reported that both the PI3K and MAPK pathways are involved in PD-1/PD-L1 regulation.21,22 An HL patient who achieved SD as the best response and progressed after 17.57 weeks exhibited a higher frequency of mutated genes related to the PI3K and MAPK pathways, including ERBB4, MAP3K9 and NF1, compared to HL patients who respond well to ICIs. The gene discussed is PDCD1; the disease is Hodgkins lymphoma.