ERBB4 and Hodgkins lymphoma: 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.