RATIONALE: Monoclonal antibodies such as rituximab can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining chemotherapy with peripheral stem cell transplantation or bone marrow transplantation may allow the doctor to give higher doses of chemotherapy drugs and kill more tumor cells.

PURPOSE: Phase II trial to study the effectiveness of rituximab and combination chemotherapy followed by bone marrow or peripheral stem cell transplantation in treating patients who have relapsed or refractory non-Hodgkin's lymphoma.

OBJECTIVES: I. Determine the complete and partial response rate of patients with relapsed or refractory B-cell non-Hodgkin's lymphoma treated with rituximab and high-dose carmustine, etoposide, cytarabine and melphalan followed by autologous bone marrow or peripheral blood stem cell transplantation.

II. Determine the toxicity profile of this regimen in these patients. III. Compare the levels of soluble CD20 antigen and rituximab blood levels with patient outcomes in this patient population.

OUTLINE: Patients receive two doses of rituximab IV over 3-4 hours 1 week apart. Stem cells from the peripheral blood or bone marrow are collected at least 1 week after the second dose of rituximab. Following stem cell collection, patients receive a third dose of rituximab IV as above between days -10 and -6. Patients then receive high-dose chemotherapy consisting of carmustine IV on day -6, etoposide IV twice daily and cytarabine IV on days -5 to -2, and melphalan IV on day -1. On day 0 patients undergo autologous bone marrow or peripheral blood stem cell transplantation. After transplantation, patients receive a fourth dose of rituximab as above at approximately day 30, and then weekly over 4 weeks at approximately 6 months in the absence of disease progression or unacceptable toxicity. Patients are followed at 1 year and then annually thereafter.

PROJECTED ACCRUAL: A total of 23-40 patients will be accrued for this study within 3 years.

• Biological: rituximab
• Drug: carmustine
• Drug: cytarabine
• Drug: etoposide
• Drug: melphalan
• Procedure: autologous bone marrow transplantation
• Procedure: peripheral blood stem cell transplantation

DISEASE CHARACTERISTICS: Diagnosis of CD20-positive B-cell non-Hodgkin's lymphoma Transplantation candidate Primary induction failure Chemotherapy refractory disease Received at least 3 prior chemotherapy regimens OR Diagnosis of mantle cell lymphoma No history of T-cell lymphoma No relapse or progression after rituximab therapy within 3 months before transplantation

PATIENT CHARACTERISTICS: Age: 19 and over Performance status: WHO 0-2 Life expectancy: At least 6 months Hematopoietic: Absolute neutrophil count at least 1,000/mm3* Platelet count more than 50,000/mm3* Hemoglobin more than 9.0 g/dL* *Unless due to lymphomatous involvement of the marrow Hepatic: Not specified Renal: Not specified Other: No serious disease or condition that would preclude study Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics Chemotherapy: See Disease Characteristics No other concurrent chemotherapy Endocrine therapy: No concurrent corticosteroids except for transient control or prevention of nausea or vomiting Concurrent non-steroidal hormones for non-lymphoma-related conditions (e.g., insulin for diabetes) allowed Radiotherapy: No concurrent external beam radiotherapy during transplantation therapy Surgery: Not specified Other: No other concurrent antitumoral or investigational agents