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.

The nature of the immunoglobulin G on the surface of B lymphocytes in chronic lymphocytic leukemia.

The nature of the immunoglobulin (Ig) G found associated with the neoplastic B lymphocytes in chronic lymphocytic leukemia that also express Igm and IgD had been investigated by absorption studies using anti-idiotypic antibodies raised against cell surface IgM from five patients. In all five cases, although cellular IgM and IgD behaved as idiotypic, the IgG did not. Thus the IgG frequently found associated with lymphocytes at this stage of differentiation is likely, at least in many cases, to be of extrinsic origin.

Anti-idiotype sera raised against surface immunoglobulin of human neoplastic lymphocytes.

The idiotypic determinants of surface immunoglobulins on B-cell lymphomas and lymphocytic leukemias represent tumor-specific antigens, individually unique for each tumor. As such they have both diagnostic and therapeutic potential, particularly for those neoplasms with no serum monoclonal immunoglobulin arising from synthesis of the protein for export. We describe the raising in animals of anti-idiotype sera directed against two examples of a nonexporting neoplasm, human chronic lymphocytic leukemia. The procedure involves exposing the cells to papain so as to remove the Fab fragments (containing the idiotypic determinants) from the surface immunoglobulin, recovering the Fab on cellulose immunosorbent particles, and immunizing animals with the immunosorbent-Fab complex.

Extracellular idiotypic immunoglobulin arising from human leukemic B lymphocytes.

The peripheral blood lymphocytes of nine out of nine patients with typical surface Ig-positive chronic lymphocytic leukemia but no paraprotein visible on serum electrophoresis have been shown by radioimmunoassay to export small amounts of pentameric IgM during culture (in the range of 2.4-7.2 ng/10(7) cells per h); three out of nine also exported monomeric IgD (0.7-1.4 ng/10(7) cells per h). Immunoglobulin turned over on the cell surface did not appear to contribute to material in the culture fluid, except possibly as vesicle-bound Ig. In three cases, which included two of the IgD producers, anti-idiotypic antibody raised against the cell surface Fab mu was used to demonstrate the idiotypic nature of the exported Ig. Anti-idiotypic antibody was also used to measure levels of idiotypic Ig in the sera of these three patients as a proportion of the total Ig. Total serum IgM was depressed in all three patients, and the idiotypic IgM represented 43%, 65%, and 96% of the IgM. The findings suggest that in typical chronic lymphocytic leukemia involving B lymphocytes, the export of a small amount of idiotypic Ig by the neoplastic cells in a common or even usual occurrence.

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 patient's eventual outcome.

The immunodeficiency of chronic lymphocytic leukaemia.

INTRODUCTION: Patients with chronic lymphocytic leukaemia (CLL) have progressive immunodeficiency and infection is the commonest cause of death. This review seeks to identify the extent of the abnormality, its cause, clinical significance and any possible remedy. SOURCES OF DATA: TJH has studied CLL for the past 40 years and has scanned or read every paper he could find published on the topic since 1970 and most of those of historical importance published before that date. He has read around the subject, covering relevant articles on immunology, cell biology, oncology and genetics. Furthermore, he has attended most major meetings dealing with CLL in this time and has written many reviews to update the state of knowledge about the topic. He receives weekly updates of papers published on CLL from PubMed and Science Direct with the keywords 'chronic lymphocytic leukaemia'. AREAS OF AGREEMENT: The immunodeficiency chiefly manifests as hypogammaglobulinaemia but involves all elements of the immune system. It is caused by the interpolation of tumour cells among immunological cells and mediated by bi-directional cell contact and secretion of cytokines, which both sustain and invigorate the tumour and suppress immunity. CLL treatment generally makes the immunodeficiency worse. Intravenous immunoglobulin is clinically effective but not cost-effective, while prophylactic antibiotics are useful in appropriate circumstances. Vaccination against infectious disease is usually ineffective. AREAS OF CONTROVERSY: Exactly how the presence of tumour cells in the immune organs renders the patient immunodeficient is controversial as is the clinical significance of minor degrees of immunodeficiency in early or indolent cases. The immunosuppressive effect of most forms of treatment is agreed, but how much this should figure in the choice of treatment is a matter of dispute. GROWING POINTS: The study of tumour-stromal interactions is an area of intense research. AREAS TIMELY FOR DEVELOPING RESEARCH: There has been little done to develop better vaccination strategies in patients with CLL, and although effective antimicrobials have been developed to protect against opportunistic infections, many are both expensive and inconvenient. More work is necessary to define precisely which patients should be offered them and when.

Chronic lymphocytic leukaemia: clinical translations of biological features.

The chronic lymphatic leukaemia (CLL) world was surprised to find that the disease split so neatly down the middle into those patients with unmutated immunoglobulin genes who were mainly men, had aggressive disease and were destined to die from their disease, on average at about 8 years from diagnosis, and those with mutated immunoglobulin genes who were equally distributed between the sexes, had indolent disease and usually died of something else a quarter of a century later. This discovery gave fresh impetus to the investigation into the biology of CLL. We now know more about, though we are still not certain of, the cell of origin of the disease and how it functions and fails to function. Intriguing clues about the roles of infectious agents and the functioning of the immune response have been scattered, but not quite put together. In addition, clinicians have been given a new tool for determining prognosis, though the tool is too clumsy for day-to-day use and surrogates are being sought. Treatment strategies based on the new biology are in development.

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.

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.

Use of a retinoblastoma gene probe to investigate clonality in Richter's syndrome.

A 69-year-old woman presented with Rai stage 0 chronic lymphocytic leukemia. Ten years later she developed a diffuse centroblastic lymphoma involving the stomach. The surface membrane phenotype of the CLL cells was MD lambda while that of the large cell lymphoma (LCL) cells was MD kappa. The two populations had different heavy and kappa light chain rearrangements. Cytogenetic analysis of the CLL cells showed a deletion involving chromosome 13, band q14, but was unsuccessful in the LCL cells. However, use of a probe (p68 RS2.0) which recognizes a variable number tandem repeat sequence in the retinoblastoma gene, localized to chromosome 13q14, showed two alleles in the LCL cells but only one in the CLL cells. These data suggest that in this case of Richter's syndrome the CLL cells and the LCL cells are clonally distinct.

Pattern of usage of the VH4-21 gene by B lymphocytes in a patient with EBV infection indicates ongoing mutation and class switching.

Following infection with EBV, patients have selectively raised serum levels of immunoglobulins encoded by the VH4-21 gene. In order to follow the detailed pattern of usage of the VH4-21 gene by blood B lymphocytes of a typical patient during infection, EBV lines were established, and transformed B cells were hybridized and cloned. In addition, to widen the genetic analysis, cDNA preparations from the EBV transformants using the gene were also analysed by polymerase chain reaction, cloning and sequencing. The majority (12/15) of the clonally distinct sequences derived from IgM utilized the VH4-21 gene in germ line configuration; however, 3/15 showed replacement mutations. For one of these, a heterogeneous pattern of mutation within the clone indicated ongoing mutation, and one sequence contained a stop codon. Three distinct clones which had rearranged to C gamma were obtained, and all were extensively mutated, with some evidence for a role for antigen in selection. Following resolution of the infection, no VH4-21-encoded products were detectable by this approach. It appears therefore that infection with EBV leads to selective activation, mutation and class switching of the VH4-21 gene, with the unusual feature that B cells harbouring deleterious mutations in the functional gene are able to survive in the circulation.

Intensive chemotherapy in myelodysplastic syndromes.

Patients with myelodysplastic syndrome (MDS) who have more than 10% blasts in their bone marrow have a very short survival. Treatment has not improved for these patients for the past 10 years and supportive care alone is still the gold standard. Intensive chemotherapy for poor prognosis MDS has been little tried, but complete remission rates are higher in such studies than in patients with acute myeloid leukaemia (AML) supervening on the MDS. Although these groups may not be comparable, and neither group is representative of the majority of patients with the MDS who are generally older, a case can be made for a randomised prospective study comparing intensive chemotherapy and supportive care alone in poor prognosis MDS. For patients with the myelodysplastic syndrome intensive chemotherapy may carry special risks. The involvement of the whole marrow in the neoplastic clone, and the likelihood of anthracycline resistance are two such hazards which may need to be circumvented.

Chronic lymphocytic leukaemia: the nature of the leukaemic cell.

Far from being the boring, inactive, inert lymphocyte that haematologists of old perceived it to be, the chronic lymphocytic leukaemia (CLL) cell has set us many complex problems. The cell is apparently stuck in G0 in cell cycle, yet expresses many activation markers. The cells apparently manufacture many cytokines and respond in vitro to even more, yet cells entering even G1 are few. The cell surface marker profile is unique. There is apparently no normal equivalent of the CLL cell. In part, this may be because the cell is malignant; malignant cells often express aberrant markers. Consistent chromosomal abnormalities are emerging but we have no idea how these abnormalities translate into molecular mistakes that dictate the peculiar nature of the cell. CLL cells carry a characteristics set of adhesion molecules, but we cannot read their homing and recycling instructions. The outstanding irregularities of the CLL cell are its CD5 positivity and its sparse surface immunoglobulin. This ought to translate as an anergic B1 cell, perhaps programmed for autoimmunity. If the tumour cell were responsible for the patient's production of immunoglobulin or secretion of autoantibodies, then a pattern might have emerged. Alas, these are the product of the normal B cells. How the CLL cell induces these complications is unknown. Thus, despite the information contained in this review, the CLL cell remains a puzzle.

Management of multiple myeloma today.

Multiple myeloma is almost invariably fatal despite a wide variety of chemotherapeutic and supportive treatment options. There are several unresolved problems with existing approaches, including the specific indications for treatment; the optimal combination of agents and doses; and the type, frequency, and timing of high-dose therapy and stem-cell transplantation. High-dose chemotherapy followed by stem-cell transplantation produces higher remission rates, but patients rarely, if ever, are cured by a single regimen. Allogeneic hematopoietic stem-cell transplantations offer a potential graft-versus-myeloma (GVM) effect. Researchers are focusing efforts on improving the safety of transplant procedures, increasing response rates to ablative therapy, and testing novel posttransplant options to improve outcomes. The newly devised National Comprehensive Cancer Network (NCCN) guidelines for treating multiple myeloma are also discussed.

Antibody therapy for treatment of multiple myeloma.

Monoclonal antibody therapy has emerged as a viable treatment option for patients with lymphoma and some leukemias. It is now beginning to be investigated for treatment of multiple myeloma. There are relatively few surface antigens on the plasma cells that are suitable for antibody-directed treatment. Possible molecules include HM1.24, CD38, ICAM-1 (CD54), CD40, CD45, CD20, and syndecan 1. There is now some clinical experience with anti-CD38 antibody in lymphoma and myeloma. However, to date, there has been minimal clinical activity observed. Additional antibodies are entering clinical trials. A new approach involves the generation of an anti-CD38 single-chain variable fragment (scFv) construct that acts as the carrier of a toxin gene instead of being conjugated directly to the toxin itself. It is hoped that expression of the toxin by CD38+ plasma cells will promote suicide of the malignant cells without affecting normal cells or generating an immunologic response to the toxin. Ongoing clinical trials are also attempting to target B-cell antigens such as CD20. Although CD20 is present only on 20% of myeloma cells, it may be present on myeloma precursor cells. This treatment has met with success in follicular lymphoma and is now being evaluated in clinical trials in both Europe and the United States for myeloma. Although these clinical trials are in very early stages, researchers are beginning to understand that antibody therapy can be used not only as a carrier molecule of radioisotopes and toxins, but also as molecules that can trigger tumor cells and promote growth arrest or apoptosis.

A phase-II trial of recombinant interleukin-2 and 5-FU chemotherapy in patients with metastatic colorectal carcinoma.

Seven patients with metastatic colorectal cancer have been treated with a regimen involving an 120-hour continuous infusion of rIL-2, 3 x 10(6) mu/m2. Entry restrictions included a Karnofsky index of greater than or equal to 80%, and a measurable lesion. One patient died of peritonitis secondary to bowel perforation at the site of the unresected tumour. One patient abandoned treatment following a pulmonary embolism during the first rIL-2 infusion. Other side effects included, pyrexia, rigors, nausea, hypotension, oliguria, weight gain, thrombocytopenia, neuropsychiatric symptoms and prerenal renal failure. Two patients have shown a greater than 50% regression in the size of their tumours and 3 have stable disease. The use of 'humanized' monoclonal antibodies together with mononuclear cells from patients receiving IL-2 infusions may provide a useful way of killing tumour cells which are resistant to lysis by LAK cells.

Analysis of soluble HLA class II antigenic material in patients with immunological diseases using monoclonal antibodies.

A quantitative assay for soluble human HLA Class II antigenic material is described. The method is a double-determinant ELISA using 2 monoclonal antibodies which recognize different epitopes on the antigen. The first rat monoclonal antibody captures antigen onto the microplate where it is then recognized by a second mouse monoclonal antibody. Bound mouse immunoglobulin is then detected by an enzyme-linked rat polyclonal antibody. The assay has been used to measure soluble HLA Class II antigen in the sera from healthy individuals and patients with leukaemia, and has shown raised levels in acute lymphoblastic but not in chronic lymphocytic leukaemia. Similar material has been identified in synovial fluid of patients with active rheumatoid arthritis. The assay is specific and simple to perform and should be applicable to probing the nature of the soluble material and its mechanism of release.

Achieving optimal outcomes in chronic lymphocytic leukaemia.

Chronic lymphocytic leukaemia (CLL) is a disease of late middle age and older. The majority of patients are diagnosed because of a lymphocytosis of at least 5 x 10(9)/L on an incidental blood count. It needs to be distinguished from mantle cell lymphoma and splenic marginal zone lymphoma by lymphocyte markers. The immunophenotype of CLL is sparse surface immunoglobulin, CD5+, CD19+, CD23+, CD79b-, and FMC7-. The disease is staged according to the presence of lymphadenopathy and/or splenomegaly and the features of bone marrow suppression. Most patients have an early stage of disease when diagnosed and perhaps 50% will never progress. This group of patients have a normal life expectancy and do not require treatment beyond reassurance. Progression involves an increasing white cell count, enlarging lymph nodes and spleen, anaemia and thrombocytopenia. Complications of progression include autoimmune haemolytic anaemia and thrombocytopenia, immunodeficiency, and the development of a more aggressive lymphoma. A range of prognostic factors is available to predict progression, but most haematologists rely on close observation of the patient. Intermittent chlorambucil remains the first choice treatment for the majority of patients. Combination chemotherapy offers no advantage. Intravenous fludarabine is probably more effective than chlorambucil, but no trial has yet shown a survival advantage for using it first rather than as a salvage treatment in patients not responding to chlorambucil. It is at least 40 times as expensive as chlorambucil. Cladribine may be as effective as fludarabine, although it has been used less and is even more expensive. Patients who relapse after chlorambucil should be offered retreatment with the same agent and if refractory should be switched to fludarabine, which may also be offered for retreatment on relapse. For patients refractory to both drugs, a variety of options are available. High dose corticosteroids, high dose chlorambucil, CHOP (cyclophosphamide, prednisolone, vincristine and doxorubicin), anti-CD52, anti-CD20 and a range of experimental drugs which are being evaluated in clinical trials. Younger patients should be offered the chance of treatment with curative intent, preferably in the context of a clinical trial. Autologous stem cell transplantation after achieving a remission with fludarabine has relative safety and may produce molecular complete remissions. Only time will tell whether some of these patients are cured but it seems unlikely. Standard allogeneic bone marrow transplant is probably too hazardous for most patients, but non-myeloablative regimens hold out the hope of invoking a graft-versus-leukaemia effect without a high tumour-related mortality. Trials of immunotherapy are exciting options for a few patients in specialised centres.

Correlation of bone marrow colony growth in the myelodysplastic syndromes with the FAB classification and the Bournemouth score.

Erythroid and myeloid colonies were grown from the bone marrow of 81 patients with myelodysplasia and the median number of colonies correlated with the FAB classification and Bournemouth score. CFU-GM were increased in CMML compared to RAEB and RAEBt. BFU-E were higher in RA than in the other FAB subgroups. Patients with a high Bournemouth score had poorer CFU-GM and BFU-E growth than those with a low score.

Response of B-cell lymphoma to a combination of bispecific antibodies and saporin.

Observations are described using a combination of two bispecific F(ab')2 antibodies (BsAb) to deliver the ribosome-inactivating protein, saporin, in the treatment of low-grade, end-stage, B-cell lymphoma. Two BsAb were used, each having one arm directed at saporin and one at the CD22 on target B cells. The BsAb, however, recognized different, non-overlapping epitopes on each molecule, a strategy which permits high-avidity double attachment of saporin to the target. The BsAb and saporin were pre-mixed at a molar ratio of 3:1 24 h before treatment and infused intravenously over a period of 1 h. Five patients have been treated, mostly with weekly doses of between 2 and 4 mg of saporin for a period of up to 6 weeks. Toxicity was minimal. Three complained of weakness and myalgia for 1 to 2 days after treatment, without objective neurological deficit or rise in serum creatine kinase. One patient produced an anti-mouse Fab' and an anti-saporin response. All patients showed a rapid and beneficial response to treatment. When present, circulating tumor cells were cleared (4/4 patients), ascitic and pleural effusions were eliminated (2/2 patients) and one patient with splenomegaly showed a marked reduction in tumor bulk. Malignant lymph nodes showed significant, but partial, shrinkage in all patients and finally marrow responded well with tumor clearance in biopsy material and impressive resolution of pancytopenia in some patients. While these responses were mainly short-lived, with tumor progression once the treatment was stopped, their speed and magnitude, and the relative lack of associated toxicity warrants further study of this treatment to determine maximum tolerated doses and therapeutic utility.