Rituximab in the treatment of diffuse large B-cell lymphomas

Prognostic and therapeutic value of somatic mutations in diffuse large B-cell lymphoma: A systematic review

Diffuse large B-cell lymphoma (DLBCL), the most common type of Non-Hodgkin lymphoma (NHL), is a highly heterogeneous and aggressive disease. Regardless of this heterogeneity, all patients receive the same first-line therapy, which fails in 30-40 % of patients, who are either refractory or relapse after remission. With the aim of stratifying patients to improve treatment outcome, different clinical and genetic biomarkers have been studied. The present systematic review aimed to identify somatic mutations that could serve as prognosis biomarkers or as therapeutic target mutations in DLBCL. Regarding their role as prognostic markers, mutations in CD58 and TP53 seem the most promising predictors of poor outcome although the combination of different alterations and other prognostic factors could be a more powerful strategy. On the other hand, different approaches regarding targeted therapy have been proposed. Therefore, mutational analysis could help guide treatment choice in DLBCL yet further studies and clinical trials are needed.

Proteasomal cysteine deubiquitinase inhibitor b-AP15 suppresses migration and induces apoptosis in diffuse large B cell lymphoma

BACKGROUND

The first line therapy for patients with diffuse large B cell (DLBCL) is R-CHOP. About half of DLBCL patients are either refractory to, or will relapse, after the treatment. Therefore, identifying novel drug targets and effective therapeutic agents is urgently needed for improving DLBCL patient survival. b-AP15, a selective small molecule inhibitor of proteasomal USP14 and UCHL5 deubiquitinases (DUBs), has shown selectivity and efficacy in several other types of cancer cells. This is the first study to report the effect of b-AP15 in DLBCL.

METHODS

Cell lines of two DLBCL subtypes, Germinal Center B Cell/ GCB (SU-DHL-4, OCI-LY-1, OCI-LY-19) and Activated B Cell/ABC (SU-DHL-2), were used in the current study. Cell viability was measured by MTS assay, proliferation by trypan blue exclusion staining assay, cellular apoptosis by Annexin V-FITC/PI staining and mitochondrial outer membrane permeability assays, the activities of 20S proteasome peptidases by cleavage of specific fluorogenic substrates, and cell migration was detected by transwell assay in these GCB- and ABC-DLBCL cell lines. Mouse xenograft models of SU-DHL-4 and SU-DHL-2 cells were used to determine in vivo effects of b-AP15 in DLBCL tumors.

RESULTS

b-AP15 inhibited proteasome DUB activities and activated cell death pathway, as evident by caspase activation and mitochondria apoptosis in GCB- and ABC- DLBCL cell lines. b-AP15 treatment suppressed migration of GCB- and ABC-DLBCL cells via inhibiting Wnt/β-catenin and TGFβ/Smad pathways. Additionally, b-AP15 significantly inhibited the growth of GCB- and ABC DLBCL in xenograft models.

CONCLUSIONS

These results indicate that b-AP15 inhibits cell migration and induces apoptosis in GCB- and ABC-DLBCL cells, and suggest that inhibition of 19S proteasomal DUB should be a novel strategy for DLBCL treatment.

The Modified Vaccination Technique

In addition to active and passive immunizations, there is a third method of immunization, the modified vaccination technique, which is based on injecting a combination of target antigens and antibodies against this antigen. The vaccine is essentially comprised of immune complexes with pre-determined immune-inducing components. When such an immune complex (target antigen × antibody against the target antigen) with a slight antigen excess is administered, it evokes a corrective immune response by the production of the same antibody with the same specificity against the target antigen that is present in the immune complex (pre-determined immune response).

Targeted Therapy for Hematologic Malignancies

Background:

The introduction of monoclonal antibodies, either as native molecules or conjugated to radioisotopes or other toxins, has led to new therapeutic options for patients with hematologic malignancies. In addition, the use of small molecules against specific cell surface receptors, enzymes, and proteins has become an important strategy in the treatment of such disorders.

Methods:

The author reviewed the published clinical trials of monoclonal antibody and other targeted therapies in hematologic malignancies.

Results:

Results from several trials demonstrate a therapeutic benefit for the use of monoclonal antibodies (either native or conjugated) and other targeted therapies, used alone or in combination with standard cytotoxic chemotherapy.

Conclusions:

Targeted therapy of hematologic malignancies seems to be an effective and less toxic approach to the treatment of such disorders. Nevertheless, additional studies are needed to determine where and when such management fits into a therapeutic regimen for any given disorder, whether upfront or as salvage therapy, alone or in combination with chemotherapy (concurrent or sequential).

Primary Gastrointestinal Non-Hodgkin's Lymphoma of the Small and Large Intestines: a Systematic Review

BACKGROUND

Primary gastrointestinal non-Hodgkin's lymphoma (PGINHL) of small and large intestines is a group of heterogeneous, rare malignancies. Optimal treatment practices remain undefined.

METHODS

A systematic review (2003-2015) was performed to assess tumor characteristics, treatment practices, and treatment outcomes of PGINHL of small and large intestines.

RESULTS

Twenty-eight studies (1658 patients) were included; five focused on follicular lymphoma subtype. Of the non-follicular patients, 59.3% presented with abdominal pain, 37.2% were located in ileocecum, and 53.6% were diffuse large B cell lymphoma subtype. The majority of patients (60.7%) were treated with a combination of surgery and chemotherapy. Forty-three percent of studies concluded an overall survival benefit with surgery; none reported increased postoperative morbidity or mortality. Survival outcomes were not typically stratified by emergent versus elective surgery. Multivariate analysis within individual studies associated B cell lymphoma and ileocecum location with higher survival, while advanced stage and B symptoms were associated with poorer survival. Patients with asymptomatic follicular lymphoma had no progression with a watchful waiting approach.

CONCLUSIONS

The majority of patients with non-follicular small and large intestinal PGINHLs are treated with both chemotherapy and surgery. Although surgery appears to be an important part of the treatment algorithm, definitive statements regarding its survival benefit remain limited due to lack of patient stratification based on timing and indication for surgery.

Novel drug targets for personalized precision medicine in relapsed/refractory diffuse large B-cell lymphoma: a comprehensive review

Diffuse large B-cell lymphoma (DLBCL) is a clinically heterogeneous lymphoid malignancy and the most common subtype of non-Hodgkin's lymphoma in adults, with one of the highest mortality rates in most developed areas of the world. More than half of DLBLC patients can be cured with standard R-CHOP regimens, however approximately 30 to 40 % of patients will develop relapsed/refractory disease that remains a major cause of morbidity and mortality due to the limited therapeutic options.Recent advances in gene expression profiling have led to the identification of at least three distinct molecular subtypes of DLBCL: a germinal center B cell-like subtype, an activated B cell-like subtype, and a primary mediastinal B-cell lymphoma subtype. Moreover, recent findings have not only increased our understanding of the molecular basis of chemotherapy resistance but have also helped identify molecular subsets of DLBCL and rational targets for drug interventions that may allow for subtype/subset-specific molecularly targeted precision medicine and personalized combinations to both prevent and treat relapsed/refractory DLBCL. Novel agents such as lenalidomide, ibrutinib, bortezomib, CC-122, epratuzumab or pidilizumab used as single-agent or in combination with (rituximab-based) chemotherapy have already demonstrated promising activity in patients with relapsed/refractory DLBCL. Several novel potential drug targets have been recently identified such as the BET bromodomain protein (BRD)-4, phosphoribosyl-pyrophosphate synthetase (PRPS)-2, macrodomain-containing mono-ADP-ribosyltransferase (ARTD)-9 (also known as PARP9), deltex-3-like E3 ubiquitin ligase (DTX3L) (also known as BBAP), NF-kappaB inducing kinase (NIK) and transforming growth factor beta receptor (TGFβR).This review highlights the new insights into the molecular basis of relapsed/refractory DLBCL and summarizes the most promising drug targets and experimental treatments for relapsed/refractory DLBCL, including the use of novel agents such as lenalidomide, ibrutinib, bortezomib, pidilizumab, epratuzumab, brentuximab-vedotin or CAR T cells, dual inhibitors, as well as mechanism-based combinatorial experimental therapies. We also provide a comprehensive and updated list of current drugs, drug targets and preclinical and clinical experimental studies in DLBCL. A special focus is given on STAT1, ARTD9, DTX3L and ARTD8 (also known as PARP14) as novel potential drug targets in distinct molecular subsets of DLBCL.

Otlertuzumab (TRU-016), an anti-CD37 monospecific ADAPTIR(™) therapeutic protein, for relapsed or refractory NHL patients

CD37 is cell surface tetraspanin present on normal and malignant B cells. Otlertuzumab (TRU-016) is a novel humanized anti-CD37 protein therapeutic. Patients with relapsed or refractory follicular non-Hodgkin lymphoma (FL), mantle cell lymphoma (MCL), or Waldenström's macroglobulinaemia (WM) received otlertuzumab at 20 mg/kg administered intravenously once a week for up to 8 weeks followed by 4 monthly doses. Sixteen patients were treated; median age was 62·5 years (range, 41-81), and median number of prior regimens was 4 (range, 1-7). Twelve patients were refractory to prior treatment, 5 were refractory to rituximab. The mean terminal half-life was 9·5 days. Lymph node reduction of ≥50% by computerized tomography scan measurements was seen in 3 of 12 patients, including one FL patient who had a partial response. One WM patient had a minor response. The most frequent adverse events were neutropenia, fatigue, nausea, thrombocytopenia, diarrhoea, and peripheral oedema; most were grade 1/2. Otlertuzumab treatment appears to have been well tolerated by the patients in this study. Clinical activity was observed in this small heterogeneous cohort of highly refractory, heavily pretreated B-cell non-Hodgkin lymphoma patients. These data suggest that further clinical investigation in non-Hodgkin lymphoma is warranted.

Novel CD20 monoclonal antibodies for lymphoma therapy

Rituximab (RTX), a monoclonal antibody (mAb) against CD20, has been widely used for lymphoma therapy. RTX in combination with cyclophosphamide /doxorubicin /vincristine /prednisone (R-CHOP) remains the standard frontline regimen for diffuse large B-cell lymphoma. However, suboptimal response and /or resistance to rituximab have remained a challenge in the therapy of B-cell non-Hodgkin's lymphoma (NHL). Novel agents are under active clinical trials. This review will summarize the latest development in new mAbs against CD20, which include second-generation mAbs, ofatumumab, veltuzumab (IMMU-106), ocrelizumab (PRO70769), and third-generation mAbs, AME-133v (ocaratuzumab), PRO131921 and GA101 (obinutumumab).

Antitumor Antibodies in the Treatment of Cancer: Fc Receptors Link Opsonic Antibody with Cellular Immunity

Engineered antibody therapeutics have provided new treatment options in cancer. Genetic evidence in man and in the mouse suggests that Fc receptor (FcR) engagement contributes mechanistically to the therapeutic activity of naked antibodies. Preferential activation of activating FcRs and limited engagement of inhibitory FcRs enhance tumor responses in mouse models. Thus, engineered Fc domains with favorable affinities for specific FcR types may prove to be clinically superior.

Advances in the treatment for haematological malignancies

Despite the progress made in the last decade in the treatment of haematological malignancies, most of the patients still have a dismal prognosis. However, the improved knowledge of tumour biology opened the possibility to develop new 'intelligent' therapeutic strategies, the so-named targeted therapies. These approaches aim to selectively kill cancer cells by basing this selectivity on both the expression of a specific molecule on their surface or the activation of particular molecular pathways secondary to malignant transformation. In this article, the authors review the main targeted therapies available in haematology, such as monoclonal antibodies, tyrosine kinase, farnesyltransferase, as well as proteasome inhibitors, antiangiogenesis compounds and antisense oligonuceotides. Finally, the authors focus on the application of imatinib mesylate in chronic myeloid leukaemia as the paradigm of molecular treatment. Although these novel therapies are beginning to fulfil their promise, continued research efforts are needed to determine the optimal role of these strategies in haemato-oncology.

Delayed reduction in left ventricular function following treatment of non-Hodgkin's lymphoma with chemotherapy and rituximab, unrelated to acute infusion reaction

We report 3 cases of reduced cardiac function with complications in non-Hodgkin's lymphoma patients who were treated with rituximab. Patients experienced reduced cardiac functions after the administration of rituximab; there was no evidence of any preceding infusion reactions. Reticulin fiber was observed diffusely in cardiac muscles. Transforming growth factor-beta levels were elevated after the administration of rituximab. We believe that continuous elevation of transforming growth factor-beta may promote the growth of reticulin fiber in cardiac muscles. Reduction in cardiac functions is a severe complication that must be considered when rituximab is administered.

Monoclonal antibody therapy of cancer

The most significant recent advances in the application of monoclonal antibodies (mAbs) to oncology have been the introduction and approval of bevacizumab (Avastin), an anti-vascular endothelial growth factor antibody, and of cetuximab (Erbitux), an anti-epidermal growth factor antibody. In combination with standard chemotherapy regimens, bevacizumab significantly prolongs the survival of patients with metastatic cancers of the colorectum, breast and lung. Cetuximab, used alone or with salvage chemotherapy, produces clinically meaningful anti-tumor responses in patients with chemotherapy-refractory cancers of the colon and rectum. In addition, the anti-HER2/neu antibody trastuzumab (Herceptin), in combination with standard adjuvant chemotherapy, has been shown to reduce relapses and prolong disease-free and overall survival in high-risk patients after definitive local therapy for breast cancer. These exciting recent results provide optimism for the development of mAbs that bind novel targets, exploit novel mechanisms of action or possess improved tumor targeting. Progress in the clinical use of radioimmunoconjugates remains hindered by complexity of administration, toxicity concerns and insufficiently selective tumor targeting.

Identification of compounds that enhance the anti-lymphoma activity of rituximab using flow cytometric high-content screening

In this report, we describe a new flow cytometry technique termed flow cytometric high-content screening (FC-HCS) which involves semi-automated processing and analysis of multiparameter flow cytometry samples. As a first test of the FC-HCS technique, we used it to screen a 2000-compound library, called the National Cancer Institute (NCI) Diversity Set, to identify agents that would enhance the anti-lymphoma activity of the therapeutic monoclonal antibody rituximab. FC-HCS identified 15 compounds from the Diversity Set that significantly enhanced the ability of rituximab to inhibit cell cycle progression and induce apoptosis in lymphoma cells. The validity of the screening results was confirmed for several compounds using additional assays of cell proliferation, apoptosis and cell growth. The FC-HCS technique was relatively simple and reliable and could process up to 1000 samples/day on a single flow cytometer. The FC-HCS technique may be useful for a variety of applications including drug discovery, immunologic monitoring of patients, functional genomics studies and tissue engineering efforts.

Rituximab: expanding role in therapy for lymphomas and autoimmune diseases

Rituximab (Rituxan) is a human-mouse chimeric monoclonal antibody that targets the B-cell CD20 antigen and causes rapid and specific B-cell depletion. Rituximab was approved in the United States in 1997 to treat low-grade or follicular, relapsed or refractory, CD20-positive B-cell non-Hodgkin's lymphoma (NHL). Since then, further clinical experience with rituximab has been incorporated into the prescribing information, which now stipulates an extended eight-week schedule, treatment of patients with refractory or relapsed bulky disease measuring >10 cm, and retreatment of patients who responded to rituximab previously. In 1998, the European Union approved rituximab (MabThera) to treat stage III/IV, follicular, chemotherapy-resistant, or relapsed NHL. Recently, the European Union also approved the use of rituximab in combination with standard chemotherapy for aggressive NHL. Many clinical trials have evaluated rituximab, alone or with other therapies, in indolent and aggressive NHL as well as other B-cell lymphoproliferative disorders. New studies are evaluating rituximab's role in first-line therapy, maintenance therapy, and stem-cell transplantation procedures. The use of rituximab against autoimmune disorders, such as rheumatoid arthritis, immune thrombocytopenic purpura, autoimmune hemolytic anemia, systemic lupus erythematosus, and multiple sclerosis, is also under investigation.

Characterization of CD20-transduced T lymphocytes as an alternative suicide gene therapy approach for the treatment of graft-versus-host disease

We have previously proposed the CD20 molecule as a novel suicide gene for T lymphocytes in the context of allogeneic bone marrow transplantation, because CD20 can be used both as a selection marker and as a killer gene after exposure to the anti-CD20 therapeutic antibody rituximab. We now report on preclinical studies using this novel system, in which the best transduction protocol, reproducibility, yield, feasibility, and functionality of the transduced T lymphocytes have been investigated with a large donor series. Wild-type human CD20 cDNA was transduced into human T lymphocytes, using a Moloney-derived retroviral vector. Alternative protocols were tested by employing either one or four spinoculations (in which cells are centrifuged in the presence of retroviral vector supernatant) and stimulating T cells with phytohemagglutinin (PHA) or anti-CD3/CD28. One spinoculation alone was sufficient to obtain approximately 30% CD20-positive cells within four experimental days. Four spinoculations significantly increased transduction to 60%. A small difference in transduction efficiency was observed between the two stimulation methods, with PHA being superior to anti-CD3/CD28. Transduced cells could be purified on immunoaffinity columns, with purity reaching 98% and yield being on average 50%. Finally, 86-97% of immunoselected T lymphocytes could be killed in vitro with rituximab and complement. More importantly, the CD20 transgene did not alter the functionality of T lymphocytes with respect to allogeneic recognition and cytotoxic response, anti-Epstein-Barr virus cytotoxic response, antigenic response to tetanus toxoid antigen, interleukin 2 (IL-2), IL-4, and interferon gamma production; chemotaxis in the presence of stromal cell-derived factor 1, phenotype for several activation markers including HLA-DR, CD25, CD69, and CD95, and T cell repertoire.

Diffuse large B-cell lymphoma: clinical implications of extranodal versus nodal presentation--a population-based study of 1575 cases

Differences in genetic origin between nodal and extranodal diffuse large B-cell lymphomas (DLBCL) exist. Using population-based data from the registry of the Danish Lymphoma Group, the present study is the first to analyse clinical implications of nodal versus extranodal presentation of DLBCL. Of 4786 newly diagnosed non-Hodgkin's lymphoma patients in a 16-year period, 1575 (33%) had DLBCL. The annual incidence rate was 2.9 per 100 000; 40% were extranodal. The clinical profile of patients with extranodal DLBCL was different from the nodal DLBCL patients. Extranodal DLBCL was associated with older age and poorer performance score, but also lower tumour burden. In extranodal DLBCL, 51% of the cases were stage I and 36% were stage IV, whereas the patients were relatively equally distributed between the four stages in nodal DLBCL. For stage I patients, extranodal DLBCL was independently associated with poor survival (P = 0.003). In contrast, among stage IV patients those with extranodal DLBCL survived longer (P = 0.009). We conclude that there are important clinical differences between nodal and extranodal DLBCL. The addition of these clinical results to the existing aetiological and genetic data suggests that the distinction between nodal and extranodal DLBCL is not only pathogenetically but also clinically important.

Variability in immunophenotype in diffuse large B-cell lymphoma and its clinical relevance

Diffuse large B-cell lymphoma (DLBCL), the single largest category of lymphoma, is a clinically and biologically heterogeneous disease entity. Clinically, patients differ in their mode of presentation and respond variably to therapy. A combination of clinical parameters can be used to predict the patient's response to therapy and survival. The pathological variability of DLBCL is expressed in morphology, immunophenotype, cytogenetic and molecular genetic features. Numerous markers detectable by immunohistochemistry and linked to different aspects of tumour biology have been studied in DLBCL, including lineage-associated and immune markers, proliferation and apoptosis markers, cell adhesion molecules, and more recently stage-specific markers of B-cell differentiation. This review summarizes these studies in regard to their clinical significance and in the light of recent advances in our understanding of the molecular pathology and histogenesis of DLBCL.

Monoclonal antibody therapy for lymphoma

Monoclonal antibodies are an exciting advance in the treatment of lymphoma. They are safe and well-tolerated, and exhibit little cross-resistance with conventional chemotherapeutic agents. In indolent lymphomas, antibody therapy has shown useful response rates, both as first-line therapy and in relapsed disease. Follicular lymphomas appear to be particularly sensitive to rituximab, and chronic lymphocytic leukaemia to alemtuzumab. In aggressive lymphomas, the addition of rituximab to CHOP chemotherapy significantly lengthens disease-free and overall survival compared to CHOP alone as first-line therapy. Newer agents, including radiolabelled antibodies, immunotoxin-linked antibodies and antibodies against novel target antigens are showing promise in phase I and II trials in a variety of clinical settings.

Diffuse large B-cell lymphoma presenting as a sacral tumor. Report of two cases

Primary lymphomas of the sacrum are rare tumors, reported only in a few cases in the literature. The authors describe two patients with diffuse large B-cell lymphomas presenting as a sacral tumor. In the first case a 52-year-old man presented with progressive back pain, bilateral radicular pain, and saddle block anesthesia secondary to a lytic, expansile soft-tissue mass. The mass arose from the sacrum and eroded through the right S-1 to S-4 foramina and extended into the epidural space of the spinal canal. On magnetic resonance imaging, the sacral mass enhanced homogeneously with Gd. In the second case a 64-year-old man presented with left-sided radicular pain, paresthesias, and progressive weakness due to a lytic soft-tissue mass in the left sacral ala extending into the left L-5 and S-1 foramina. Metastatic workup in each patient demonstrated unremarkable findings. In both cases, an open biopsy procedure was performed after nondiagnostic examination of needle biopsy samples. Histopathological examination showed evidence consistent with diffuse large B-cell lymphoma in both patients. In the first case the disease was classified as Stage IAE, and the patient subsequently underwent four cycles of cyclophosphamide/doxorubicin/vincristine/prednisone (CHOP)- and rituximab-based chemotherapy followed by consolidation radiotherapy. In the second case the disease was also classified as Stage IAE, and the patient underwent CHOP-based chemotherapy and consolidation radiotherapy. In both cases radiography demonstrated a decrease in size of the sacral lymphomas. The authors review the clinical, radiological, and histological features of sacral lymphomas. Lymphoma should be considered in the differential diagnosis of sacral tumors.

Rituximab: a review of its use in non-Hodgkin's lymphoma and chronic lymphocytic leukaemia

Rituximab is an anti-CD20 monoclonal antibody that has demonstrated efficacy in patients with various lymphoid malignancies, including indolent and aggressive forms of B-cell non-Hodgkin's lymphoma (NHL) and B-cell chronic lymphocytic leukaemia (CLL). While the optimal use of the drug in many clinical settings has yet to be clarified, two pivotal trials have established rituximab as a viable treatment option in patients with relapsed or refractory indolent NHL, and as a standard first-line treatment option when combined with cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) chemotherapy in elderly patients with diffuse large B-cell lymphoma (the most common type of aggressive NHL). The former was a noncomparative trial in relapsed indolent NHL (follicular and small lymphocytic subtypes) with clinical responses achieved in about half of patients treated with rituximab 375 mg/m(2) intravenously once weekly for 4 weeks, which was similar to some of the most encouraging results reported with traditional chemotherapeutic agents. The latter was a randomised comparison of eight cycles of CHOP plus rituximab 375 mg/m(2) intravenously (one dose per cycle) versus CHOP alone in previously untreated elderly patients (60 to 80 years of age) with diffuse large B-cell lymphoma. In this pivotal trial, 2-year event-free and overall survival were significantly higher with rituximab plus CHOP, and there was no increase in clinically significant adverse effects compared with CHOP alone. Treatment with rituximab is generally well tolerated, particularly in terms of adverse haematological effects and serious or opportunistic infections relative to standard chemotherapy. Infusion-related reactions occur in the majority of patients treated with rituximab; these are usually mild to moderate flu-like symptoms that decrease in frequency with subsequent infusions. In approximately 10% of patients, however, severe infusion-related reactions develop (e.g. bronchospasm, hypotension). These reactions are usually reversible with appropriate interventions and supportive care but there have been rare reports of fatalities.

CONCLUSIONS

Clinical trials with rituximab indicate that the drug has broad application to B-cell malignancies, although further clarification is needed to determine its optimal use in many of these clinical settings. Importantly, rituximab in combination with CHOP chemotherapy has emerged as a new treatment standard for previously untreated diffuse large B-cell lymphoma, at least in elderly patients. Compared with conventional chemotherapy, rituximab is associated with markedly reduced haematological events such as severe neutropenia, as well as associated infections. Rituximab may be particularly suitable for elderly patients or those with poor performance status, and its tolerability profile facilitates its use in combination with cytotoxic drugs.

PHARMACODYNAMIC PROPERTIES

Rituximab is a mouse/human chimaeric IgG(1)-kappa monoclonal antibody that targets the CD20 antigen found on the surface of malignant and normal B lymphocytes. Although treatment with rituximab induces lymphopenia in most patients, typically lasting about 6 months, a full recovery of B lymphocytes in the peripheral blood is usually seen 9-12 months after therapy, as CD20 is not expressed on haematopoietic stem cells. CD20 is, however, expressed on >90% of B-cell non-Hodgkin's lymphomas (NHL) and to a lesser degree on B-cell chronic lymphocytic leukaemia (CLL) cells. Although not fully elucidated, the cytotoxic effects of rituximab on CD20-positive malignant B cells appears to involve complement-dependent cytotoxicity, complement-dependent cellular cytotoxicity, antibody-dependent cellular cytotoxicity and induction of apoptosis. In addition, in vitro data indicate that rituximab sensitises tumour cells to the effects of conventional chemotherapeutic drugs.

PHARMACOKINETIC PROPERTIES

Serum rituximab concentrations increased in proportion to dose across a wide range of single- and multiple-dose intravenous regimens in patients with B-cell NHL. When administll NHL. When administered at a dose of 375 mg/m(2) once weekly for 4 weeks in a pivotal trial in patients with relapsed or refractory indolent B-cell NHL (follicular or small lymphocytic subtypes), peak serum concentrations essentially doubled from the first (239.1 mg/L) to the fourth (460.7 mg/L) infusion, while elimination half-life (t(1/2)) increased from 76.3 to 205.8 hours (3.2 to 8.6 days). The concomitant increase in serum rituximab concentrations and t(1/2) with each successive infusion may be due, at least in part, to the elimination of circulating CD20-positive B cells and reduction or saturation of CD20-binding sites after the initial infusions of rituximab. The pharmacokinetic properties of rituximab are also characterised by wide inter-individual variability, and serum drug concentrations that are correlated with clinical response. Although pharmacokinetic data are limited in patients with aggressive forms of NHL, such as diffuse large B-cell lymphoma, rituximab appears to have a similar pharmacokinetic profile in these patients to that in patients with indolent B-cell NHL. The pharmacokinetics of rituximab are also reported to be similar whether the drug is administered with or without cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) chemotherapy.

THERAPEUTIC USE

A number of studies have demonstrated efficacy of intravenous rituximab in patients with various lymphoid malignancies of B-cell origin, including indolent (e.g. follicular lymphoma) and aggressive (e.g. diffuse large B-cell lymphoma) forms of NHL, and CLL, but the drug has not yet been approved for use in CLL, and approved indications in NHL vary between countries. In the US, for example, rituximab is available for the treatment of patients with low-grade or follicular, relapsed or refractory, CD20-positive B-cell NHL. In Europe, the drug has similar approval for relapsed or refractory follicular NHL as in the US, but has also been approved for use in combination with CHOP chemotherapy for the most common aggressive form of NHL (CD20-positive, diffuse large B-cell lymphoma). Rituximab was approved for these indications primarily on the basis of results from two pivotal trials. In Japan, rituximab has been approved for indolent B-cell NHL and mantle cell lymphoma (an aggressive form of B-cell NHL), primarily on the basis of results of a Japanese phase II trial. Indolent NHL: Results of several studies evaluating rituximab 375 mg/m(2) once weekly for 4 weeks in patients with indolent forms of B-cell NHL (primarily follicular and small lymphocytic lymphomas) showed objective response (OR) rates ranging from approximately 40-60% in those receiving the drug for relapsed or refractory indolent B-cell NHL, and slightly higher (50-70%) for those receiving rituximab as first-line therapy. In a pivotal trial in 166 patients with relapsed or refractory low-grade or follicular B-cell NHL, intent-to-treat (ITT) analysis showed an OR rate of 48%, and a projected median time to progression of 13 months. Encouraging data are also emerging on the use of rituximab in combination with chemotherapeutic agents (e.g. CHOP, fludarabine-containing regimens) or other drugs (e.g. interferon-alpha2a) in previously untreated patients with indolent forms of B-cell NHL (primarily follicular and small lymphocytic subtypes). Rates for OR were consistently around 95%, with the majority being complete responses (CRs). Follow-up data from a study in 40 patients with low-grade or follicular B-cell NHL treated with rituximab plus CHOP as first-line therapy showed that responses were durable with a progression-free survival and median duration of response >5 years.Bcl-2 gene rearrangement (t14;18) occurs in malignant cells in up to 85% of patients with follicular lymphoma, and minimal residual disease in peripheral blood and bone marrow can be monitored using polymerase chain reaction (PCR). In several studies assessing blood and/or bone marrow, rituximab has achieved molecular response (conversion from PCR-positive to PCR-negative bcl-2 status) in at least half of the patients. Aggressive NHL: Studies with rituximab as monotherapy in aggressive B-cell NHL, a potentially curable disorder, have generally been restricted to patients with relapsed or recurrent disease, since CHOP has traditionally been the standard first-line treatment regimen. However, promising results from phase II monotherapy studies prompted further clinical investigation of rituximab in conjunction with chemotherapy. Thus, most studies with rituximab in patients with aggressive forms of B-cell NHL have involved combination therapy, including a pivotal randomised trial comparing eight cycles of standard CHOP therapy plus rituximab 375 mg/m(2) (one dose per cycle) versus CHOP alone in 399 previously untreated elderly patients (60-80 years of age) with diffuse large B-cell lymphoma. Results of the pivotal trial showed a clear advantage for rituximab plus CHOP versus CHOP in terms of event-free survival (primary endpoint) at 2 years (57% vs 38%, p < 0.001). Overall survival at 2 years (70% vs 57%, p < 0.01) and CR rate (76% vs 63%, p < 0.01) were also higher with the rituximab-CHOP combination. Other, smaller trials with rituximab in combination with CHOP or other chemotherapeutic regimens, either as first-line therapy or for patients with relapsed or refractory aggressive B-cell NHL, have also shown promising results in terms of clinical response rates.CLL: In relatively small trials (n < 40) conducted primarily in patients with relapsed or refractory B-cell CLL, rituximab monotherapy (various regimens) achieved OR rates of 23-45%, with median duration of response ranging from approximately 3-10 months. (ABSTRACT TRUNCATED)

Caspase-mediated cell death in hematological malignancies: theoretical considerations, methods of assessment, and clinical implications

Apoptosis, the caspase-mediated cell death, plays an important role in the etiology, pathogenesis and therapy of a variety of diseases. Abnormalities of apoptosis regulation, resulting in either its inhibition or enhancement, play a key role in the development of various malignant hematological disorders. Several routine and new therapeutic strategies in Oncohematology are based on apoptosis modulation. Cytotoxic effects of most antineoplastic drugs are based on induction of apoptosis. The accurate estimate of incidence of apoptosis, therefore, is of importance in Oncohematology. In this review we provide an overview of the methods designed to measure the incidence of apoptosis, including the recently developed assays that are based on detection of caspases activation. We also review recent findings on the role of caspase-mediated cell death in hematological malignancies and discuss their clinical implications, including new therapeutical strategies that evolve from these findings.

Identification of tumor-specific antibodies in patients with breast cancer vaccinated with gene-modified allogeneic tumor cells

Thirty HLA-A2 women with metastatic breast cancer received up to 14 vaccinations with MDA-MB-231-CD80, an HLA-A2 allogeneic breast cancer cell line, which had been lipofected with the cDNA for the CD80 costimulatory molecule. Tumor cells were administered with BCG or GM-CSF as an adjuvant. Sera obtained before and after vaccination were analyzed for antibodies to tumor cell lysate, MUC1, HER2/neu and p53. Since the cell line was grown in fetal bovine serum (FBS), sera were also analyzed for antibodies to FBS. Eighteen of 24 patients for whom sera were available exhibited anti-FBS activity at baseline. Eleven of these 18 patients and all six patients without baseline anti-FBS activity showed an increased titer after vaccination. The anti-FBS activity required that serum samples be absorbed in excess FBS to detect specific antibodies to tumor cell lysate. A two-fold increase in the titer of IgG specific to tumor cell lysate was observed in 6 patients. Eight of 24 patients made an antibody response to HER-2/neu, four of 24 to MUC1 and one of 24 to p53. Although antibody production to a variety of tumor cell-associated antigens was detected our results suggest that a whole cell vaccine comprising a CD80-transfected allogeneic breast cancer cell line with adjuvant BCG or GM-CSF was not a reliable method to induce significant antibody responses in women with advanced breast cancer.

Rituximab provides durable remission in a patient with refractory aggressive diffuse B-cell lymphoma failing salvage chemotherapy

The outcome of patients with aggressive refractory diffuse large B-cell lymphoma (DLCL) is generally poor. A 43-year-old female with DLCL, who relapsed after first line chemotherapy (CHOP--cyclophosphamide, doxorubicin, vincristine, and prednisone) and progressed despite salvage chemotherapy (EPOCH-etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin), was treated effectively with 8 cycles of Rituximab. She is without evidence of disease with a follow-up of 32 months. We report this case to bring to attention the possibility of sustained durable remission with single agent Rituximab in refractory DLCL.