Autologous Stem Cell Transplantation with Yttriumm-90-Ibritumomab Tiuxetan (Zevalin) Plus BEAM Conditioning in Patients with Refractory Non-Hodgkin Diffuse Large B-Cell Lymphoma: Results of a Prospective, Multicenter, Phase II Clinical Trial

Autologous stem cell transplantation (ASCT) is the treatment of choice for patients with relapsed diffuse large B-cell lymphoma (DLBCL). However, in the rituximab era, patients with persistent disease receiving ASCT have a very poor outcome. Recent studies including radioimmunotherapy as part of the conditioning treatment suggest an improved outcome for this group of patients.

We have evaluated, in a prospective phase 2 study, the safety and efficacy of yttriumm-90-ibritumomab tiuxetan (Zevalin) combined with standard BEAM in refractory DLBCL patients. Thirty patients with induction failure (primary refractory; n=18) or refractory to salvage immunochemotherapy at relapse (n=12) were included in the study. Patients' response was evaluated with PET-CT according to 2007 Cheson's revised response criteria.

Patients with a median age of 53 years (range, 25–67) received Zevalin at a fixed dose of 0.4mCi/kg (maximum dose 32 mCi) 14 days prior to standard BEAM. Histology included de novo DLBCL (22) and transformed DLBCL (8). Patients received a median of 3 (range, 2–6) prior therapies before ASCT. All patients had active disease at the time of ASCT, with 25 patients considered to be chemorefractory to the last treatment. Median CD34⁺ cell dose infused was 3.9 × 10⁶/kg (range, 2–18.3). All patients engrafted. Median time to neutrophil recovery (>500/μl) was 11 days (9–21), and to platelet recovery (>20.000/μl) was 13 days (11–35). Overall response at day +100 was 70% (95% CI, 53.6–86.4) with 60% (95% CI, 42.5–77.5) complete responses. Eleven patients have died. One due to a cerebral hemorrhage before ASCT and 1 due to sepsis immediately post-transplant. Seven patients died of disease progression, and 2 patients died due to late complications: bacterial sepsis and secondary acute leukemia. One patient developed a myelodysplastic syndrome (refractory anemia with excess blasts-2) 33 months after TASP, while being in CR of its lymphoma. After a median follow-up of 22.7 months for alive patients (range, 12.2–39.0), 2-year overall and progression-free survival is 65% (95% CI, 47.8–82.8) and 63% (95% CI, 45.5–80.4), respectively.

ASCT with conditioning including Zevalin radioimmunotheray plus BEAM is safe, and results in a very high response rate with promising survival in this very poor prognosis group of refractory DLBCL patients.

No relevant conflicts of interest to declare.