Terry J. Hamblin

B-Cell Chronic Lymphocytic Leukemia: A Bird of a Different Feather

PURPOSE To review the recent major advances in the molecular and cell biology of B-cell chronic lymphocytic leukemia (B-CLL). METHODS We analyzed the nature of malignant B-CLL B cells and their interactions with the microenvironment. RESULTS B-CLL is a malignancy of a mantle zone-based subpopulation of anergic, self-reactive, activated CD5+ B cells devoted to the production of polyreactive natural autoantibodies. It is the quintessential example of a human malignancy that primarily involves defects in the induction of programmed cell death. An abnormal karyotype is observed in about 50% of patients with B-CLL. Patients with 13q14 abnormalities show heavy somatic mutation and have a benign disease. Trisomy 12 is associated with unmutated VH genes, atypical cellular morphology, and progressive disease. Extended cell survival is further shielded by a kinetic refractoriness likely promoted by abnormalities of the B-cell antigen receptor complex and favored by some cytokines that highlight a reciprocal dialog between malignant B and T cells. Because the tumor cells act as the major accessory cells, the accumulating malignant B-cell population per se is a hurdle to the production of normal antibodies and leads to a progressive and severe hypogammaglobulinemia. Conceivably, in the presence of certain immunoglobulin genes and when the T-cell control becomes deficient, activated malignant B cells may become able to present self-antigens and drive residual normal B cells to produce polyclonal autoantibodies restricted to self-antigens expressed only by blood cells and cause autoimmune cytopenias. CONCLUSION The distinctiveness of B-CLL B cells explains why B-CLL is different from other B-cell tumors and accounts for the development of immune deficiency and autoimmunity.

DNA vaccines with single-chain Fv fused to fragment C of tetanus toxin induce protective immunity against lymphoma and myeloma

Vaccination with idiotypic protein protects against B-cell lymphoma, mainly through anti-idiotypic antibody. For use in patients, DNA vaccines containing single-chain Fv derived from tumor provide a convenient alternative vaccine delivery system. However, single-chain Fv sequence alone induces low anti-idiotypic response and poor protection against lymphoma. Fusion of the gene encoding fragment C of tetanus toxin to single-chain Fv substantially promotes the anti-idiotypic response and induces strong protection against B-cell lymphoma. The same fusion design also induces protective immunity against a surface Ig-negative myeloma. These findings indicate that fusion to a pathogen sequence allows a tumor antigen to engage diverse immune mechanisms that suppress growth. This fusion design has the added advantage of overcoming potential tolerance to tumor that may exist in patients.

Chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia is the commonest form of leukaemia in Europe and North America, and mainly, though not exclusively, affects older individuals. It has a very variable course, with survival ranging from months to decades. Major progress has been made in identification of molecular and cellular markers that could predict disease progression in patients with chronic lymphocytic leukaemia. In particular, the mutational profile of immunoglobulin genes and some cytogenetic abnormalities are important predictors of prognosis. However, these advances have raised new questions about the biology, prognosis, and management of chronic lymphocytic leukaemia, some of which are addressed here. In particular, we discuss how better understanding of the function of the B-cell receptor, the nature of genetic lesions, and the balance between proliferation and apoptosis have affected our ability to assess prognosis and to manage chronic lymphocytic leukaemia. Available treatments generally induce remission, although nearly all patients relapse, and chronic lymphocytic leukaemia remains an incurable disease. Advances in molecular biology have enhanced our understanding of the pathophysiology of the disease and, together with development of new therapeutic agents, have made management of chronic lymphocytic leukaemia more rational and more effective than previously. Unfortunately, we know of no way that chronic lymphocytic leukaemia can be prevented. Early detection is practised widely, but seemingly makes no difference to the patients eventual outcome.

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.

Immunological abnormalities in myelodysplastic syndromes. I: Serum immunoglobulins and autoantibodies

The immunoglobulin levels and autoantibody profiles of 104 patients with primary myelodysplastic syndromes (MDS), classified according to the FAB criteria, were analysed. Eight patients, four with coexistent non‐Hodgkins lymphomas, three with chronic lymphocytic leukaemia and one with a lymphoplasmacytoma, were excluded from the final analysis of immunoglobulin levels. Serum protein electrophoresis and immunoelectro‐phoresis revealed the presence of monoclonal gammopathy in 12 patients (12·5%). Of the remaining 84 patients, a polyclonal rise in serum immunoglobulins was present in 27 (32%) while a further 16 (19%) had low immunoglobulin levels. The direct antiglobulin test was positive in eight out of 98 patients tested (8·1%), and organ and non‐organ specific autoantibodies were present in 15 out of 67 patients tested (22·3%). Two patients had associated pernicious anaemia (PA), two hypothyroidism, and one PA with hypothyroidism. Three patients had sero‐negative rheumatoid arthritis. These results demonstrate that there is a high incidence of immunological abnormalities in MDS.

Prognostic features of chronic myelomonocytic leukaemia: a modified Bournemouth score gives the best prediction of survival

Summary. We have studied the clinical and laboratory features of 53 cases of chronic myelomonocytic leukaemia (CMML) defined according to the FAB criteria. A granulocyte count of < 16 x 109/l or a monocyte count of < 2.6 x 109/l correlated with a poorer survival, but the best predictor of poor survival was the modified ‘Bournemouth’ score in which one point each was allocated for Hb < 10 g/dl, neutrophils < 2.5 x 109/l or > 16 x 109/l, platelets < 100 x 109/l and bone marrow blasts > 5%. A score of 2 or more was predictive of poor survival (Chi2= 10.25; P < 0.001). Those patients with low monocyte and neutrophil counts and a low modified Bournemouth score tended to have a clinical course similar to refractory anaemia (RA) with an indolent course not requiring treatment and long survival whereas those with high monocyte and neutrophil counts and a high modified ‘Bournemouth’ score have a clinical course resembling that of refractory anaemia with excess of blasts (RAEB).

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.

Clonal history of a human follicular lymphoma as revealed in the immunoglobulin variable region genes.

Summary. The variable region genes used to encode the immunoglobulin expressed by tumour cells of a patient with follicular lymphoma have been identified and sequenced. Initially, a lymph node biopsy was analysed and revealed usage of VH and Vκ genes which had numerous substitutions as compared with the closest germ line genes. The pattern of mutations in VH was consistent with a role for positive selection by antigen. In addition, there was evidence in both VH and Vκ sequences for clonal heterogeneity.

The occurrence and significance of V gene mutations in B cell—Derived human malignancy

The classification of B cell tumors has relevance for refining and improving clinical strategies. However, consensus has been difficult to establish, and although a scheme is now available, objective criteria are desirable. Genetic technology will underpin and extend current knowledge, and it is certain to reveal further subdivisions of current tumor categories. The Ig variable region genes of B cell tumors present a considerable asset for this area of investigation. The unique sequences carried in neoplastic B cells are easily isolated and sequenced. In addition to acting as clone-specific markers of each tumor, they indicate where the cell has come from and track its history following transformation. There is emerging clinical value in knowing whether the cell of origin has encountered antigen and has moved from the naive compartment to the germinal center, where somatic mutation is activated. This is amply illustrated by the subdivision of chronic lymphocytic leukemia into two subsets, unmutated or mutated, each with very different prognosis. Other tumors may be subdivided in a similar way. Microarray technology is developing rapidly to probe gene expression and to further divide tumor categories. All these genetic analyses will provide objective data to enhance both our understanding of B cell tumors and our ability to treat them.

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 μg/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 μg/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 μg/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.