The trial hypothesis is that the new protocol will improve the event-free survival, a measure integrating unfavorable events such as death, disease progression and treatment complications, particularly infections, in the low risk-group compared to the results of the PTLD-1 trial. In very high-risk patients data from the PTLD-1 and PTLD-1/3 trial have shown that the current treatment is not sufficient to control the disease. Death due to disease progression was observed in more than 80% of patients. Here, rituximab combined with alternating chemotherapy cycles of CHOP and DHAOx (+GCSF) may increase treatment efficacy with an acceptable toxicity profile.