Impaired CD163 Mediated Hemoglobin-Scavenging and Hemolytic Crisis in Patients Treated with CD33 Targeted Chemotherapy (Gemtuzumab Ozogamicin, Mylotarg^TM)

TY - ABST

T1 - Impaired CD163 Mediated Hemoglobin-Scavenging and Hemolytic Crisis in Patients Treated with CD33 Targeted Chemotherapy (Gemtuzumab Ozogamicin, MylotargTM)

AU - Maniecki, Maciej Bogdan

AU - Hasle, Henrik

AU - Friis-Hansen, Lennart

AU - Lausen, Birgitte

AU - Nielsen, Ove Juul

AU - Bendix, Knud

AU - Moestrup, Søren Kragh

AU - Møller, Holger Jon

N1 - Conference code: 49

PY - 2007

Y1 - 2007

N2 - Hemoglobin liberated to plasma during intravascular hemolyses is rapidly bound to haptoglobin. The hemoglobin-haptoglobin complexes undergo endocytosis through the monocyte/macrophage specific scavenger receptor for hemoglobin (CD163). This mechanism protects against oxidative and NO-scavenging adverse effects of free hemoglobin. In this study, we describe a novel syndrome of severe intravascular hemolysis and serious hemolytic crisis due to impaired hemoglobin scavenging in three acute myeloid leukemia patients following CD33-directed therapy with the immunotoxin gemtuzumab ozogamicin (GO, MylotargTM). A synchronous high free hemoglobin, haptoglobin, and low bilirubin after septicemia-induced intravascular hemolysis indicated abrogated clearance of haptoglobin-hemoglobin complexes. This was further supported by low levels of plasma soluble CD163 and a concordant low number of CD163-expressing monocytes. We show that CD163 positive monocytes and bone marrow macrophages coexpress CD33 thus suggesting that the GO-induced cellular cytotoxicity of CD33 positive cells eradicates a significant part of the CD163 positive monocytes and macrophages. The patients had severe inflammation and serious organ failure symptoms that may be a direct effect of the persistent high level of free hemoglobin. One of the patients had a fatal outcome whereas, the other two recovered from the hemolytic episode, and the peripheral blood CD163 expression returned to normal. The risk of a serious hemolytic crisis should be considered following CD33-targeted chemotherapy. Furthermore, the cases provide circumstantial evidence of a key role of CD163 plasma hemoglobin clearance in vivo.

AB - Hemoglobin liberated to plasma during intravascular hemolyses is rapidly bound to haptoglobin. The hemoglobin-haptoglobin complexes undergo endocytosis through the monocyte/macrophage specific scavenger receptor for hemoglobin (CD163). This mechanism protects against oxidative and NO-scavenging adverse effects of free hemoglobin. In this study, we describe a novel syndrome of severe intravascular hemolysis and serious hemolytic crisis due to impaired hemoglobin scavenging in three acute myeloid leukemia patients following CD33-directed therapy with the immunotoxin gemtuzumab ozogamicin (GO, MylotargTM). A synchronous high free hemoglobin, haptoglobin, and low bilirubin after septicemia-induced intravascular hemolysis indicated abrogated clearance of haptoglobin-hemoglobin complexes. This was further supported by low levels of plasma soluble CD163 and a concordant low number of CD163-expressing monocytes. We show that CD163 positive monocytes and bone marrow macrophages coexpress CD33 thus suggesting that the GO-induced cellular cytotoxicity of CD33 positive cells eradicates a significant part of the CD163 positive monocytes and macrophages. The patients had severe inflammation and serious organ failure symptoms that may be a direct effect of the persistent high level of free hemoglobin. One of the patients had a fatal outcome whereas, the other two recovered from the hemolytic episode, and the peripheral blood CD163 expression returned to normal. The risk of a serious hemolytic crisis should be considered following CD33-targeted chemotherapy. Furthermore, the cases provide circumstantial evidence of a key role of CD163 plasma hemoglobin clearance in vivo.

M3 - Conference abstract in journal

SN - 0006-4971

JO - Blood

JF - Blood

IS - 3684

T2 - Annual Meeting of the American Society of Hematology

Y2 - 6 December 2007 through 11 December 2007

ER -