CD38 expression in chronic lymphocytic leukemia is regulated by the tumor microenvironment.

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease with a highly variable outcome. The prognosis of patients with CLL may be predicted using a number of biomarkers, including the level of CD38 expression at the leukemic cell surface. This study investigates the hypothesis that CD38 expression by CLL cells reflects interactions with nonmalignant cells within pseudofollicles in secondary lymphoid tissue where tumor cell proliferation is thought to occur. CD38 expression is higher in tissues that contain pseudofollicles compared with those that do not. In addition, we show that CD38 expression in CLL is dynamic, changes in response to contact with activated CD4(+) T cells, and identifies cells that are primed to proliferate. Finally, we demonstrate close contact between activated CD4(+) T cells and proliferating tumor in primary patient tissue. Proliferating tumor cells in lymph nodes express CD38, which is in turn associated with an increased number of CD31(+) vascular endothelial cells. Although the factors resulting in colocalization of tumor, T cells, and endothelium remain unclear, the existence of these cellular clusters may provide an explanation for the association between CD38 expression and adverse outcome in CLL and suggests novel therapeutic targets.

Fludarabine, cyclophosphamide and rituximab for chronic lymphocytic leukemia: no country for old men?

The combination of fludarabine, cyclophosphamide and rituximab is regarded as the gold-standard treatment for chronic lymphocytic leukemia in many parts of the world, although rituximab has not yet been licensed for this use. To date, no randomized, controlled trials have been fully published that demonstrate the superiority of this regimen over other treatments. The results of an open-label, phase II trial with long-term follow-up data on 300 patients with chronic lymphocytic leukemia treated with this regimen are discussed here. Although this study reported impressive efficacy, information on modern prognostic markers such as immunoglobulin gene mutational status and chromosomal deletions was absent, and so it is impossible to say whether the most challenging cases, as identified by these markers, were included in the trial. The most important toxicity was prolonged cytopenia, which occurred both at the end of treatment and later after bone-marrow recovery. At least half of patients with chronic lymphocytic leukemia are over 70 years of age and this regimen might be too toxic for such individuals.

Determination of how many immunoglobulin variable region heavy chain mutations are allowable in unmutated chronic lymphocytic leukaemia - long-term follow up of patients with different percentages of mutations.

The choice of 98% sequence homology for immunoglobulin heavy chains to distinguish between mutated and unmutated versions of chronic lymphocytic leukaemia (CLL) was arbitrary and was chosen to account for supposed polymorphisms. Some authors chose 97% or even 95%. This study examined survival curves for cohorts of patients with varying degrees of sequence homology. All patients with <97% homology behaved as if mutated. Those with 97-98% homology were more aggressive than the mutated cases, but less aggressive than those with >98% homology.

Have we been wrong about ionizing radiation and chronic lymphocytic leukemia?

It is almost axiomatic that chronic lymphocytic leukemia (CLL) is not caused by ionizing radiation. This assumption has been challenged recently by a critical re-appraisal of existing data. A recent paper implicated radon exposure in Czech uranium miners as a possible cause of CLL and in this issue of Leukemia Research the first paper examining the incidence of CLL among those exposed to radiation from the accident at the nuclear power plant in Chernobyl is published. It suggests that CLL occurring among the clean-up workers was of a more aggressive form than is normally seen in the community.

Prognostic markers in chronic lymphocytic leukaemia.

Rai and Binet staging of chronic lymphocytic leukaemia (CLL) is being superseded by new prognostic markers. The mutational status of the immunoglobulin variable region heavy-chain genes segregates the disease into more benign and more malignant versions, and has been confirmed as an important prognostic marker in prospective clinical trials. A search for surrogate markers for this difficult-to-perform assay has led to flow cytometric assays for CD38 and ZAP-70 expression, although in both cases there are problems with standardization and interpretation of the assays. A separate pathway of research has revealed two chromosomal aberrations--deletions of 11q and 17p--as important prognostic markers. Fluorescent in-situ hybridization has made their detection readily available. These five markers are in different stages of evaluation, but some of them are ready to be used for risk-adapted therapy in clinical trials. Other assays are in earlier stages of assessment.

Is "leukemia" an appropriate label for all patients who meet the diagnostic criteria of chronic lymphocytic leukemia?

Chronic lymphocytic leukemia is a frightening diagnosis which we believe is mistakenly applied to patients who will live their whole lives without symptoms referable to this diagnosis and never require treatment for it. Changes in the threshold of lymphocytosis required for the diagnosis have led to many more people being inappropriately diagnosed. In addition, modern prognostic factors have enabled us to predict with a fair degree of accuracy which patients presenting with a lymphocytosis will have a benign course and which will require treatment. We propose a new category of benign monoclonal lymphocytosis be recognized, better to reflect reality.

Autoimmune complications of chronic lymphocytic leukemia.

Autoimmune complications are common in chronic lymphocytic leukemia (CLL), occurring in up to a quarter of all patients during the course of the illness. By far the most common manifestation is autoimmune hemolytic anemia (AIHA), followed by immune thrombocytopenia (ITP). It is not true to say that autoimmunity is confined to the formed elements of the blood since conditions such as paraneoplastic pemphigus and acquired angioedema do occur in CLL, but nonhematologic autoimmunity is very rare indeed. The pathogenesis of autoimmunity in CLL is unknown. It may be related to the ability of the CLL cells to act as antigen-presenting cells (APCs), and to process antigen (particularly the Rh protein) so as to reveal cryptic peptides that are seen as foreign by helper T cells. It is likely that a failure of regulatory T-cell function is also involved. Autoimmune episodes may be triggered by treatment, particularly with purine analogues. Such episodes are often severe and may be fatal. Treatment of CLL-associated autoimmunity follows conventional protocols, but non-response to primary treatments is not uncommon. Promising results have been obtained with cyclosporine and rituximab.

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.

The management of anemia in the myelodysplastic syndrome.

How to treat anemia in the myelodysplastic syndrome (MDS) is controversial. Many health care systems refuse to fund erythropoietin on grounds of health economics. A new paper on the effect of anemia in MDS on cardiac remodeling has suggested that a higher treatment threshold level for hemoglobin should be introduced. This would have an impact of the calculation of risk/benefits.

Alemtuzumab in combination with methylprednisolone is a highly effective induction regimen for patients with chronic lymphocytic leukemia and deletion of TP53: final results of the national cancer research institute CLL206 trial.

PURPOSE: In chronic lymphocytic leukemia (CLL), TP53 deletion/mutation is strongly associated with an adverse outcome and resistance to chemotherapy-based treatment. In contrast, TP53 defects are not associated with resistance to the anti-CD52 monoclonal antibody alemtuzumab or methylprednisolone. In an attempt to improve the treatment of TP53-defective CLL, a multicenter phase II study was developed to evaluate alemtuzumab and methylprednisolone in combination. PATIENTS AND METHODS: Thirty-nine patients with TP53-deleted CLL (17 untreated and 22 previously treated) received up to 16 weeks of treatment with alemtuzumab 30 mg three times a week and methylprednisolone 1.0 g/m(2) for five consecutive days every 4 weeks. Antimicrobial prophylaxis consisted of cotrimoxazole, itraconazole, and aciclovir (or valganciclovir for asymptomatic cytomegalovirus viremia). The primary end point was response as assigned by an end-point review committee. Secondary end points were safety, progression-free survival (PFS) and overall survival (OS). RESULTS: The overall response rate, complete response rate (including with incomplete marrow recovery), median PFS, and median OS were 85%, 36%, 11.8 months, and 23.5 months, respectively, in the entire cohort and 88%, 65%, 18.3 months, and 38.9 months, respectively, in previously untreated patients. Grade 3 to 4 hematologic and glucocorticoid-associated toxicity occurred in 67% and 23% of patients, respectively. Grade 3 to 4 infection occurred in 51% of the overall cohort and in 29% of patients less than 60 years of age. Treatment-related mortality was 5%. CONCLUSION: Alemtuzumab plus methypredisolone is the most effective induction regimen hitherto reported in TP53-deleted CLL. The risk of infection is age related and, in younger patients, seems only marginally higher than that associated with rituximab, fludarabine, and cyclophosphamide.

Searching for surrogates for IGHV mutations in chronic lymphocytic leukemia.

Despite a startling separation of chronic lymphocytic leukemia (CLL) into two clinically different diseases with average survivals of 8 years and 25 years, the mutational status of immunoglobulin variable region (IGHV) genes has not entered routine clinical practice to assess prognosis, although its assessment is regarded as an essential for clinical trials. Instead, surrogates that may be measured by flow cytometry have been sought. Measurements of the expression of CD38 and ZAP-70 have been the most popular assays for prognosis although both are in their own ways unsatisfactory. Many other candidates have emerged, but none has been universally endorsed. As the assay for IGHV mutations has been standardized the level of difficulty has diminished and as greater numbers of cases have been assessed it has become clear that there is even more information to be gathered from the study of the sequence of IGHV genes. It has been recognized that stereotypy within CLL is associated with more specific clinical features than mere longevity and an even greater heterogeneity has been revealed. It seems clear that the search for surrogacy is futile and that IGHV mutational status should become a routine investigation in CLL.

The TCL1 mouse as a model for chronic lymphocytic leukemia.

The TCL1 mouse has been proposed as a mouse model for chronic lymphocytic leukemia. This review details how it resembles the aggressive form of the disease rather than the more common indolent form. Although fulfilled predictions in the human disease based on investigations in the mouse model are at present lacking, there are remarkable similarities between human and mouse leukemias that have led to interesting observations on the pathophysiology of chronic lymphocytic leukemia and have identified putative therapeutic targets.

Non-hemic autoimmunity in CLL.

Non-hemic autoimmune complications of chronic lymphocytic leukemia are very rare compared to autoimmune haemolytic anemia, which occurs in between 10% and 20% of patients and immune thrombocytopenia, which occurs in between 1% and 2% of patients. A clear relationship has only been established with three non-hemic syndromes: acquired angioedema, glomerulonephritis and paraneoplastic pemphigus. The first is a result of a secreted product of the tumor, but the last two seem to be a product of the disordered immune system, and may be triggered by treatment with purine analogues suggesting a mechanism involving regulatory T cells. Apart from Herpes Zoster infections, neurological syndromes are rare in CLL and most have been attributed to either leukemic infiltration of the CNS or progressive multifocal leukoencephalopathy.

Myocardial iron loading by magnetic resonance imaging T2* in good prognostic myelodysplastic syndrome patients on long-term blood transfusions.

Magnetic resonance imaging (MRI) was used to quantify myocardial iron loading by T2* in 11 transfusion-dependent good prognostic myelodysplastic syndrome (MDS) patients. Myocardial T2*, left ventricular function and hepatic T2* were measured simultaneously. Patients had been on transfusion therapy for 13-123 months and had serum ferritin levels of 1109-6148 microg/l at the time of study. Five patients had not commenced iron chelation and had been transfused with a median of 63 red cell units and had a median serum ferritin level of 1490 microg/l. Six patients were on iron chelation and had been transfused with a median of 112 red cell units and had a median serum ferritin level of 4809 mug/l. Hepatic iron overload was mild in two, moderate in seven and severe in two patients. The median liver iron concentration was 5.9 mg/g dry weight in chelated patients and 9.5 mg/g in non-chelated patients (P = 0.17; not significant). Myocardial T2* indicated absent iron loading in 10/11 patients (91%; 95% confidence interval 62-98%) and borderline-normal in one patient. Left ventricular function was normal in all patients. No correlation was observed between increasing serum ferritin levels, hepatic iron overload and myocardial T2*. A long latent period relative to hepatic iron loading appears to predate the development of myocardial iron loading in transfusion-dependent MDS patients.