High CD33-antigen loads in peripheral blood limit the efficacy of gemtuzumab ozogamicin |(Mylotarg®) treatment in acute myeloid leukemia patients

Gemtuzumab ozogamicin (Mylotarg®) induces remission in approximately 30% of relapsed AML patients. We previously demonstrated that gemtuzumab infusion results in near-complete CD33 saturation in peripheral blood, and that saturating gemtuzumab levels result in continuous binding and internalization of gemtuzumab due to renewed CD33 expression. We now demonstrate that a high CD33-antigen load in peripheral blood is an independent adverse prognostic factor, likely due to peripheral consumption of gemtuzumab. Indeed, CD33 saturation in bone marrow is significantly reduced (40-90% saturation) as compared with CD33 saturation in corresponding peripheral blood samples (>90%). In vitro, such reduced CD33 saturation levels were strongly related with reduced cell kill. Apparently, high CD33-antigen loads in blood consume gemtuzumab and thereby limit its penetration into bone marrow. Consequently, CD33 saturation in bone marrow is reduced, which hampers efficient cell kill. Therefore, gemtuzumab should be administered at higher or repeated doses, or, preferably, after reduction of the leukemic cell burden by classical chemotherapy

Small intestinal infarction: a fatal complication of systemic oxalosis

Primary hyperoxaluria is a rare genetic disorder characterised by calcium oxalate nephrolithiasis and nephrocalcinosis leading to renal failure, often with extrarenal oxalate deposition (systemic oxalosis). Although ischaemic complications of crystal deposition in vessel walls are well recognised clinically, these usually take the form of peripheral limb or cutaneous ischaemia. This paper documents the first reported case of fatal intestinal infarction in a 49 year old woman with systemic oxalosis and advocates its consideration in the differential diagnosis of an acute abdomen in such patients. Key Words: primary hyperoxaluria • oxalosis • intestinal infarctio

Karyotype in acute myeloblastic leukemia: Prognostic significance for bone marrow transplantation in first remission: A European Group for Blood and Marrow Transplantation Study

The presentation cytogenetic result was correlated with outcome for 999 patients with acute myeloblastic leukemia (AML) having bone marrow transplantation (BMT) in first complete remission (CR1). The karyotype at diagnosis was classified according to the modified Chicago classification. Allogeneic BMT (AlloBMT) was performed in 500 patients and autologous BMT (ABMT) in 499 patients. For both groups, an abnormal chromosome (abn) 5 and/or 7 or a hypodiploid karyotype had a poor outcome, whereas t(15;17), pseudodiploidy, hyperdiploidy and diploidy were associated with a standard prognosis. Abn (16) and t(8;21) were also of standard prognosis for ABMT, but favorable for AlloBMT. When comparing AlloBMT and ABMT in patients with favorable or standard cytogenetics, AlloBMT was of benefit for remission duration and leukemia-free survival (LFS). Patients with an unfavorable karyotype had a similar outcome, regardless of type of BMT. By multivariate analysis, cytogenetics at diagnosis had the strongest prognostic value for relapse, LFS, and survival in AlloBMT. In ABMT, cytogenetics influenced relapse and LFS. We concluded that the karyotype at diagnosis had important prognostic implication in AML grafted in CR1. (C) 1997 by The American Society of Hematology