Pitfalls and limitations of ZAP-70 detection in chronic lymphocytic leukemia

ZAP-70 Shapes the Immune Microenvironment in B Cell Malignancies

Zeta-chain-associated protein kinase-70 (ZAP-70) is a tyrosine kinase mainly expressed in T cells, NK cells and a subset of B cells. Primarily it functions in T cell receptor (TCR) activation through its tyrosine kinase activity. Aberrant expression of ZAP-70 has been evidenced in different B cell malignancies, with high expression of ZAP-70 in a subset of patients with Chronic Lymphocytic Leukemia (CLL), associating with unfavorable disease outcomes. Previous studies to understand the mechanisms underlying this correlation have been focused on tumor intrinsic mechanisms, including the activation of B cell receptor (BCR) signaling. Recent evidence also suggests that ZAP-70, intrinsically expressed in tumor cells, can modulate the cross-talk between malignant B cells and the immune environment, implying a more complex role of ZAP-70 in the pathogenesis of B cell malignancies. Meanwhile, the indispensible roles of ZAP-70 in T cell and NK cell activation also demonstrate that the autologous expression of ZAP-70 in the immune environment can be a central target in modulation of tumor immunity. Here we review the evidences of the link between ZAP-70 and tumor immunology in the microenvironment in B cell malignancies. Considering an emerging role of immunotherapies in treating these conditions, understanding the distinct molecular functions of ZAP-70 in a broader cellular context could ultimately benefit patient care.

The Impact and Prognostic Significance of Chronic Lymphocytic Leukemia Upregulated 1 (CLLU1) Gene Expression in Patients with Chronic Lymphocytic Leukemia: A Single Center Experience

OBJECTIVES

To determine CLLU1 gene levels and the relationship of that gene among other prognostic parameters in patients with chronic lymphocytic leukemia.

METHODS

Bone-marrow infiltration pattern, β2-microglobulin (β 2-M), cluster of differentiation (CD)38, and ZAP-70 status were recorded. CLLU1 levels were assessed by real-time polymerase chain reaction (RT-PCR) and expressed as folds. The relationship between CLLU1 and other known prognostic parameters was evaluated.

RESULTS

CLLU1 expression was positive in 81 patients and negative in 3 patients. The median (interquartile range [IQR]) CLLU1 level was 6.45 folds (3.75-16.57 folds) in patients with β 2-M normal values and 16.22 folds (3.91-62.00 folds) in patients with increased β 2-M (P = .15). Patients with a higher CD38 value than the median level had 3 times higher CLLU1 levels than the other group (P = .07). The median (IQR) CLLU1 level was 4.25 folds (2.75-13.71 folds) in patients with CLL who tested negative on ZAP-70, whereas it was 49.52 folds (15.06-446.36 folds) in those who tested positive via ZAP-70 (P = .005).

CONCLUSIONS

CLLU1 is a specific parameter to CLL, and its level corresponds well with the ZAP-70 level.

CD49d shows superior performance characteristics for flow cytometric prognostic testing in chronic lymphocytic leukemia/small lymphocytic lymphoma

BACKGROUND

CD49d is emerging as a powerful adverse prognostic marker in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). However, flow cytometric testing for CD49d has not yet been widely adopted in the United States, in part due to the lack of establishment of its performance characteristics in the clinical setting, especially in comparison with the more common CLL/SLL prognostic markers CD38 and ZAP-70.

METHODS

CD49d expression levels in 124 CLL/SLL cases were assessed among peripheral blood (PB), bone marrow (BM), and lymph node (LN) specimens and correlated with available CD38 and ZAP-70 expression and cytogenetic findings. For 10 PB/BM specimens, the stability of CD49d, CD38, and ZAP-70 expression was assessed at <24 hours, 48 hours, 72 hours, and 96 hours.

RESULTS

39% (28 of 71) PB, 56% (18 of 32) BM, and 71% (15 of 21) LN involved by CLL/SLL were CD49d+, using a ≥30% threshold. The mean for the CD49d+ cases was 2.8 standard deviations (SD) above the cutoff for positivity, compared with 1.7 SD for CD38 and 1.1 SD for ZAP-70. CD49d demonstrated the lowest mean SD (0.91) and coefficient of variation (CV) (8.0%) compared with CD38 (SD = 2.1, CV = 10.4%) and ZAP-70 (SD = 9.8, CV = 40.5%) in stability studies over a 96-hours time period. CD49d+ CLL/SLL correlated with trisomy 12 (P = 0.025) and lack of isolated deletion (13q) (P = 0.005). CD38+ CLL/SLL correlated with deletion (11q) (P = 0.025). ZAP-70 did not correlate with any underlying cytogenetic abnormality.

CONCLUSIONS

CD49d is a robust adverse prognostic marker in CLL/SLL with superior performance characteristics. © 2016 International Clinical Cytometry Society.

A novel diagnostic biosensor for distinguishing immunoglobulin mutated and unmutated types of chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL), the immunoglobulin heavy-chain variable (IgVH) region may be mutated (Ig-mutated CLL) or unmutated (Ig-unmutated CLL); and the presence or absence of mutations in this region of CLL cells distinguishes two clinically distinct forms. It is important for physicians to distinguish between patients with Ig-unmutated CLL, where typically have more indolent disease with median survivals close to 25 years, and Ig-mutated CLL, where have more aggressive disease with median survivals around eight years. In this work, a biosensor capable of diagnosis and distinguishing between these two types of CLL was reported. The biosensor was fabricated by modifying a gold electrode with gold nanoparticles (AuNPS) followed by coating of ZAP70 oligonucleotide probe on the surface to detect specific sequence of ZAP70 gene. ZAP70 could predict the IgVH mutation status and is a good marker for differentiating Ig-mutated and Ig-unmutated CLL and serve as prognostic marker. First, we focused on achieving hybridization between probe and its complementary sequence. Hybridization between probe and target was determined with electrochemical impedance spectroscopy (EIS). Then, our efforts turned to optimize the conditions for the detection of any point mutation and also to maximize the selectivity. Under optimal conditions, the biosensor has a good calibration range between 2.0 × 10(-14) and 1.0 × 10(-9)molL(-1), with ZAP70 DNA sequence detection limit of 4.0 × 10(-15)molL(-1). We successfully detect hybridization first in synthetic samples, and ultimately in blood samples from patients. Experimental results illustrated that the nanostructured biosensor clearly discriminates between mutated and non-mutated CLL and predict the IgVH mutation status, which it has been considered as the single most informative stage independent prognostic factor in CLL.

Differential expression and function of CD27 in chronic lymphocytic leukemia cells expressing ZAP-70

Chronic lymphocytic leukemia is a malignancy driven by abberant B cell signaling and survival. Leukemic B cells accumulate in the peripheral blood and the lymphoid organs where contact with stromal cells and T cells provide critical survival signals. Clinical severity of CLL is associated with several prognostic markers including expression of the kinase ZAP-70. ZAP-70 expression enhances signaling via the B cell antigen receptor and is associated with increased cell adhesion and migration capacity. Here we report that ZAP-70-positive CLL patients display significantly higher expression of the TNF superfamily receptor and memory marker CD27 than do ZAP-70 negative patients. CD27 expression by CLL was acutely elevated upon BCR cross-linking, or upon ectopic expression of ZAP-70. CD27 expression correlated with functional capacity to adhere to stromal cells and antibody blockade of CD27 impaired CLL binding to stroma. These results provide the first evidence for differential expression of CD27 among CLL prognostic groups, suggest a role for ZAP-70 dependent signaling in CD27 induction and implicate CD27 in cell-cell interactions with the lymphoid tissue microenvironment.

Frontline low-dose alemtuzumab with fludarabine and cyclophosphamide prolongs progression-free survival in high-risk CLL

Frontline FCA increases progression-free survival in CLL and, in a post hoc analysis, also survival in younger patients. With the low-dose approach, no increase in treatment related mortality is seen.