The sequential treatment schedule has been designed for several reasons: concurrent Avelumab and RCHOP might result in reduced efficacy of Avelumab owing to the high dose prednisolone component of RCHOP; immune related toxicities of Avelumab given concurrently with RCHOP might result in chemotherapy dose delays and reduced chemotherapy efficacy; the Avelumab plus rituximab prephase will allow for the preliminary assessment of nonchemotherapy agents Avelumab plus rituximab in treatment naïve patients.