Allogeneic Transplantation for Adult Acute Lymphoblastic Leukemia (ALL) with Rituximab or Campath I-H.

Because of potential synergy with chemotherapy and non-overlapping toxicity, we investigated the addition of Rituximab or Campath 1-H to the standard myeloablative conditioning regimen of cyclophosphamide (60 mg/kg daily x 2) and total body irradiation (12.0 Gy in four fractions) prior to allogeneic transplantation for ALL. Transplantation was performed on day 0. Rituximab was added if patients’ disease expressed CD20+ > 20% by flow-cytometry. It was administered (375 mg/m² ) on days −6, −1, +7 and +14. Campath I-H (10 mg daily intravenously, days −6 to −2) was added if patients’ CD20 expression was <20% and CD52 >20%. Thirty-two adult consecutive patients were studied. Eleven were in first remission with poor prognostic features, 11 in 2^nd remission, and 10 were ≥ 3^rd remission, or in relapse. Twenty-nine patients had B-cell, two had T-cell and one had an undifferentiated phenotyping. The study group included 19 males and 13 females of median age 35 yrs (range, 19–57). Median # of prior chemoregimens received was 2 (range, 1–6). In both groups of patients, prophylaxis for GVHD consisted of a combination of tacrolimus and methotrexate. Pharmacokinetic studies in patients who received Campath I-H showed no detectable level of the antibody one-day prior to- or after the infusion of the donor graft. Median follow-up for survivors was 19 months. Outcomes were:

No prognostic factor was found to be of significance for survival, disease-free survival, or relapse. This included: age (<35 vs ≥ 35), source of graft, disease status at transplant, # prior regimens (<2 vs ≥ 2), acute or chronic GVHD, use of Rituximab or Campath. Our results indicate that the addition of Rituximab or Campath I-H in allogeneic transplantation for ALL is safe. There was no delay in engraftment and no added toxicity or risk of mortality. Longer follow-up is needed to evaluate the impact of this strategy upon survival and relapse.