Acute myeloblastic leukemia (AML-M2) expressing CD19 B-cell lymphoid antigen without myeloid surface antigens

Chimeric antigen receptor (CAR) T therapies for the treatment of hematologic malignancies: clinical perspective and significance

Chimeric Antigen Receptor (CAR) T cell therapies - adoptive T cell therapies that have been genetically engineered for a new antigen-specificity - have displayed significant success in treating patients with hematologic malignancies, leading to three recent US Food and Drug Administration approvals. Based on the promise generated from these successes, the field is rapidly evolving to include new disease indications and CAR designs, while simultaneously reviewing and optimizing toxicity and management protocols. As such, this review provides expert perspective on the significance and clinical considerations of CAR T cell therapies in order to provide timely information to clinicians about this revolutionary new therapeutic class.

CD19: a biomarker for B cell development, lymphoma diagnosis and therapy

The human CD19 antigen is a 95 kd transmembrane glycoprotein belonging to the immunoglobulin superfamily. CD19 is classified as a type I transmembrane protein, with a single transmembrane domain, a cytoplasmic C-terminus, and extracellular N-terminus. CD19 is a biomarker for normal and neoplastic B cells, as well as follicular dendritic cells. CD19 is critically involved in establishing intrinsic B cell signaling thresholds through modulating both B cell receptor-dependent and independent signaling. CD19 functions as the dominant signaling component of a multimolecular complex on the surface of mature B cells, alongside complement receptor CD21, and the tetraspanin membrane protein CD81 (TAPA-1), as well as CD225. Through study of CD19 transgenic and knockout mouse models, it becomes clear that CD19 plays a critical role in maintaining the balance between humoral, antigen-induced response and tolerance induction. This review also summarized latest clinical development of CD19 antibodies, anti-B4-bR (an immunotoxin conjugate), blinatumomab (BiTE), and SAR3419 (huB4-DM4), a novel antibody-drug conjugate.

Lineage conversion from acute lymphoblastic leukemia to acute myeloid leukemia on rearrangement of the IgH gene in a patient with Down syndrome

A patient with Down syndrome (DS) at the time of diagnosis of acute lymphoblastic leukemia (ALL) had a relapse with acute myeloid leukemia (AML) after 4 years of complete remission. Although the diagnosis was AML, the leukemic blasts at relapse showed an immunoglobulin H rearrangement that turned out to be identical to that of the initial ALL blasts. It is thought that the leukemic precursor cells of this patient had the potential to differentiate into both lymphoid and myeloid lineages. This case is important for investigating target cells for leukemogenesis in DS.

A novel translocation t(2;9)(q14;p12) in AML-M2 with an uncommon phenotype: myeloperoxidase-positive and myeloid antigen-negative

We report a case of acute myeloid leukemia (AML-M2) expressing myeloperoxidase (MPO) but no myeloid antigens. A few cases with this discordant phenotype have been reported and an association has been suggested between the lack of CD13 and CD33 in MPO positive AML and the presence of t(8;21). Cytogenetic and molecular analyses performed in our case showed 48,XY,+Y,+8,t(2;9)(q14;p12). We believe that combined approaches can contribute to detect particular AL cases like the present one, that confirms the heterogeneity of AML. However, further studies are needed to clarify the relationship between phenotypic aberrations and cytogenetic abnormalities.