Jenny Orchard

ZAP-70 expression and prognosis in chronic lymphocytic leukaemia

BACKGROUND Chronic lymphocytic leukaemia (CLL) is a heterogeneous disease; many patients never need treatment, whereas some have poor outcomes. New treatments, which can induce complete remissions, allow patients with poor outlook to be treated while they are still asymptomatic. Whether or not the IgVH gene is mutated is the best predictor of clinical outcome, but this assay is unsuited to the routine laboratory. The gene coding for ZAP-70, a tyrosine kinase protein normally expressed in T and NK cells, has been shown by gene-expression profiling to be differentially expressed between patients with mutated and unmutated IgVH genes. We assessed whether ZAP-70 could be used as a prognostic marker in CLL. METHODS We developed a flow cytometry assay for ZAP-70 protein expression and investigated its concordance with ZAP-70 mRNA expression, IgVH gene mutational status, and clinical outcome in 167 patients with CLL. FINDINGS We showed high concordance between ZAP-70 protein expression and IgVH gene mutations. 108 patients (65%) had mutated IgVH genes and were ZAP-70 negative; 46 (28%) had unmutated IgVH genes and were ZAP-70 positive. Findings were discordant in 13 patients: six (4%) had mutated IgVH genes but were ZAP-70 positive, and seven (4%) had unmutated IgVH genes and were ZAP-70 negative. Expression of mRNA showed 97% concordance with ZAP-70 protein. Median survival was 24.4 years (95% CI 15.1-33.8) in ZAP-70 negative patients and 9.3 years (7.0-11.5) in those who were ZAP-70 positive (hazard ratio 5.5, 2.8-.8). INTERPRETATION ZAP-70 protein, which can be measured by flow cytometry in the general laboratory, is a reliable prognostic marker in CLL, equivalent to that of IgVH gene mutational status.

Fludarabine-related autoimmune haemolytic anaemia in patients with chronic lymphocytic leukaemia.

Summary. We have treated 52 patients with chronic lymphocytic leukaemia (CLL) with fludarabine; 12 developed severe autoimmune haemolysis. Only three had a previous history of haemolytic anaemia. Six out of eight patients retreated with fludarabine after control of their haemolysis developed an exacerbation of the haemolytic anaemia. The cause of autoimmune phenomena in CLL is not known, but our findings reinforce the view that they are caused by a disturbance in immunoregulatory T cells. Fludarabine is a known suppressor of T‐cell function.

Fludarabine is effective in the treatment of splenic lymphoma with villous lymphocytes

We report on the use of fludarabine in four patients with splenic lymphoma with villous lymphocytes (SLVL). All four had relapsed after, or failed to respond to, recommended first‐line therapies. In each case fludarabine resulted in a complete clinico‐haematological response with minimal toxicity, which, in the two patients with long‐term follow‐up, proved durable. Fludarabine is effective in the treatment of SLVL and should be considered as both a first‐line therapeutic option as well as salvage therapy in this condition.

ZAP-70 in B cell malignancies

ZAP-70 has emerged as a protein of potential prognostic importance in chronic lymphocytic leukemia (CLL) following gene expression profiling which compared the 2 well established prognostic sub-sets, those with unmutated and mutated IgVH genes. This protein tyrosine kinase (PTK), known to be of importance in T and NK cell signaling but absent in normal peripheral B cells, is expressed in the majority of the poorer prognosis unmutated CLL and absent in most cases with mutated IgVH genes. ZAP-70 has been shown to be functionally important in the CLL cases in which it is expressed; it is also important in B cell development in mice and there is preliminary evidence for its expression in human B cell progenitors and activated B cells. Whether its expression in a sub-set of CLL cases is a result of a more activated cell type or a reflection of the stage of maturation of the transforming event(s) in CLL is open to debate. ZAP-70 is expressed in a minority of other B cell tumors but correlation with IgVH gene mutational status is lacking. The problems with ZAP-70 measurement, which has yet to be standardized, are reviewed together with its current status as a prognostic marker in CLL.

Autoimmune Haemolysis in Patients with B-CLL Treated with Chlorodeoxyadenosine (CDA)

We have treated 19 B-chronic lymphocytic leukaemia (B-CLL) patients with CDA (Leustat, Janssen-Cilag). Four patients developed severe autoimmune haemolytic anaemia, and 2 of these had severe reticulocytopenia due to red cell aplasia/hypoplasia. Two patients died as a complication of the haemolysis one during the primary episode, with a clinical course suggestive of transfusion associated graft-versus-host disease (taGVHD), and one following a relapse of haemolysis. The onset of haemolysis occurs within 4 cycles of CDA therapy and is temporally related to the T-lymphocyte nadir induced by CDA. The presence of a positive DAT prior to therapy in 3 of 4 patients developing haemolysis suggests that the CDA induced T-lymphocytopenia may exacerbate the tendency of certain CLL patients to autoimmune haemolysis.