Radioimmunotherapy with 131-I tositumomab enhanced survival in good prognosis relapsed and high-risk diffuse large B-cell lymphoma (DLBCL) patients receiving high-dose chemotherapy and autologous stem cell transplantation
8013 Background: The 5-year overall survival (OS) for pts with relapsed chemosensitive DLBCL with standard transplantation is approximately 40–50%. We previously piloted the addition of standard outpatient radioimmunotherapy (RIT) with 131-I tositumomab to the transplant regimen for patients with relapsed chemoresistant NHL. This phase I study demonstrated a 3 yr OS of 55% in these poor prognosis patients (JCO 23: 461–467, 2005). The current study is a follow-up phase II study in good prognosis relapsed and high risk DLBCL patients using 131-I tositumomab with BEAM (BCNU, etoposide, cytarabine, and melphalan) followed by an autologous stem cell transplant. Methods: Forty patients were accrued to the study between 2000–2005. The patients had a median age of 54 yrs (26–75) and all had a diagnosis of DLBCL. The patients had a median of two prior chemotherapies before transplant and 88% had received prior Rituximab. All patients had chemotherapy sensitive disease at the time of stem cell transplant. Following stem cell collection, all patients received a stem cell preparative regimen of 75 cGy total body dose of 131-I tositumomab (dosimetric dose day -19 and therapeutic day -12) followed by a standard BEAM transplant regimen. Autologous unpurged stem cells were infused on day 0. The median time of follow-up of the survivors is 28 months (3–68). Results: Seventy eight percent of the patients had a complete remission following the transplant. The 3 year progression free survival (PFS) is 70% (95% CI - 48 - 84%) and the 3 year OS is 81% (95% CI - 61 - 91%). The entire transplant can be delivered on an outpatient basis. No increased toxicity compared to a similar cohort receiving BEAM alone could be detected. Conclusions: The addition of 131-I tositumomab to BEAM and autologous stem cell transplant for relapsed or high-risk chemosensitive DLBCL produces a 3-yr OS of 81% without excess toxicity. This compares favorably to historical controls. This regimen is currently being tested in a phase III trial in the BMT/CTN of Rituximab/BEAM vs. 131-I tositumomab/BEAM in patients with relapsed chemosensitive DLBCL. No significant financial relationships to disclose.