DSHNHL R3 is a randomized clinical phase II study. The main objective is to estimate the efficacy of rituximab as a prophylactic medication for prevention of graft-versus-host-disease after allogeneic peripheral stem cell transplantation in patients with a high risk relapse of aggressive B-cell Non-Hodgkin's lymphoma. The most important secondary objective is to estimate the efficacy of allogeneic stem cell transplantation in this clinical situation.

Patients in the age of 18 to 65 years with a high- risk relapse of a histology proven aggressive Non-Hodgkin's-lymphoma are eligible for the trial. Aggressive Non-Hodgkin's lymphoma within this study is defined as:

B-NHL:

follicular lymphoma grade III° lymphoblastic (precursor) lymphoma diffuse large cell cell lymphoma any subtype and variant including primary mediastinal lymphoma mantle cell lymphoma, blastic variant

T-NHL:

precursor T cell lymphoma peripheral T cell lymphoma, any subtype and variant angioimmunoblastic lymphoma anaplastic large cell lymphoma, any subtype NK / T cell lymphoma High risk relapsed or progressive disease is defined as (a) primary progressive disease, (b) early relapse after less than 12 month of remission duration and at least one risk factor according to the international prognostic index (IPI), (c) relapse or progression after high dose chemotherapy and autologous transplantation, (d) relapse or progression and lack of an autologous stem cell product.

Patients with this type of progression / relapse should receive rituximab plus ifosfamide/carboplatin/etoposide (R-ICE) or rituximab plus dexamethasone/high dose ARA-C/cisplatinum as salvage therapy (recommendation, not part of study medication). In patients biwth T cell lymphoma rituximab may be replaced by alemtuzumab. If at least stable disease is achieved, patients can be definitely included.

With inclusion, patients were randomized to receive either 375 mg/ m2 of rituximab at weeks 3, 4, 5, 6, 25, 26, 27, 28 after allogeneic stem cell transplantation or no additional medication.

Conditioning for transplantation consisted of Fludarabine 125 mg/m2, Busulfan 12 mg/kg and cyclophosphamide 120 mg/kg.

Short-term (day 1 to day 28) mycophenolat mofetil and tacrolimus are used as basis GVHD prophylaxis in all patients. Anti-thymocyte globulin can be used due to the centres decision in patients with unrelated donors

Inclusion Criteria:

• histology proven aggressive non Hodgkin's lymphoma and
• primary progressive disease or
• early relapse after less than 12 month of remission duration and at least one risk factor according to the international prognostic index (IPI or
• relapse or progression after high dose chemotherapy and autologous transplantation or
• relapse or progression and lack of an autologous stem cell product.

Exclusion Criteria:

• severe comorbidity or impaired organ function
• hypersensitivity to used drugs
• HIV positivity
• active hepatitis
• other active malignant disease