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PubMed2004

Dual kinase inhibition in the treatment of breast cancer: initial experience with the EGFR/ErbB-2 inhibitor lapatinib.

Dual inhibition of ErbB-1 (EGFR) and ErbB-2 (HER-2) tyrosine kinases has been found to exert greater biologic effects in the inhibition of signaling pathways promoting cancer cell proliferation and survival than inhibition of either receptor alone. The novel dual EGFR/ErbB-2 tyrosine kinase inhibitor lapatinib (GlaxoSmithKline; Research Triangle Park, NC) has been shown to inhibit tumor cell growth in vitro and in xenograft models for a variety of human tumors. Preliminary findings in a phase I study of lapatinib in patients with solid tumors indicate doses up to 1,800 mg per day are well tolerated. No grade 4 toxicities were observed and only two of 43 patients had grade 3 toxicity (diarrhea). Clinical activity of lapatinib was observed in these patients; nine patients with a variety of tumors remained on study for > or =4 months, one with a complete response (head and neck cancer). In a phase IB study in pretreated metastatic cancer patients with disease that could be biopsied, grade 1 or 2 diarrhea and rash were the most common adverse events. Three patients with breast cancer refractory to trastuzumab (Herceptin; Genentech, Inc.; South San Francisco, CA) had partial responses and 12 patients with a variety of tumors had stable disease. Assessment of biologic correlates in these patients indicates that increased tumor cell apoptosis on the terminal deoxynucleotide transferase-mediated dUTP nick-end labeling assay correlates with clinical response. Lapatinib currently is being evaluated in phase II and phase III trials in patients with metastatic breast cancer.

Antineoplastic Agents↗
PubMed2004

Overcoming endocrine therapy resistance by signal transduction inhibition.

Endocrine therapy is the most effective systemic treatment for patients with hormone-receptor-positive (HR(+)) breast cancer. Unfortunately, efficacy is often limited by the onset of resistance, which is almost inevitable for patients with advanced disease. Several patterns of endocrine resistance are recognizable clinically, including: A) tumors that are inherently insensitive to all attempts at estrogen receptor (ER) targeting despite expression of ER (pan-endocrine therapy resistance); B) tumors that are estrogen dependent but resistant to one or more specific endocrine therapies (agent-selective resistance); and C) tumors that initially respond but subsequently progress (acquired resistance). Current insights into the molecular basis for these resistance patterns are rudimentary, but are most clearly illuminated by investigations that focus on the crosstalk between the ErbB or HER peptide growth factor family and the ER. The data are sufficiently compelling to be addressed by ongoing clinical trials that examine combinations of endocrine agents and either trastuzumab (Herceptin; Genentech, Inc.; South San Francisco, CA) or ErbB-specific tyrosine kinase (TK) inhibitors. Preliminary data from a small "proof of concept" phase II study of letrozole (Femara; Novartis Pharmaceuticals Corporation; East Hanover, NJ) and trastuzumab demonstrated durable responses despite tamoxifen (Nolvadex; AstraZeneca Pharmaceuticals; Wilmington, DE) resistance. Efficacy was variable, however, despite the selection of patients on the basis of ER and ErbB-2 coexpression. Complicating matters further, resistance often occurs in the absence of any evidence for ErbB TK family member expression. In the absence of a clear target, common downstream signal transduction proteins that are known to intersect with the ER pathway can be inhibited to address resistance, including G proteins with farnesyltransferase inhibitors and molecular target of rapamycin (mTOR) with rapamycin analogues. With a number of phase III clinical trials now under way, major advances in the endocrine treatment of advanced disease are possible.

Alkyl and Aryl Transferases↗
PubMed2004

Monoclonal antibodies, small molecules, and vaccines in the treatment of breast cancer.

The human epidermal growth factor receptor (HER, ErbB) family of receptors is considered an important therapeutic target, and various types of molecularly based small molecules, including monoclonal antibodies, protein tyrosine kinase inhibitors, and therapeutic vaccines, are in development as potential therapies for metastatic breast cancer. Trastuzumab (Herceptin; Genentech, Inc.; South San Francisco, CA), the first approved monoclonal antibody for HER-2 (ErbB-2)-overexpressing metastatic breast cancer, provided the proof of principle that targeting specific receptors results in clinical benefit. Other monoclonal antibodies and the small molecule dual protein tyrosine kinase inhibitors show great promise as treatments for metastatic breast cancer but require evaluation in clinical trials to assess their benefits. Therapeutic vaccines may have a role, particularly in early-stage disease, but they are associated with greater limitations and study design issues that make their evaluation difficult. Optimum combination therapy regimens with a variety of novel approaches that incorporate small molecule targeted therapies need to be developed, and the population most likely to benefit from targeted therapies needs to be identified.

Antibodies, Monoclonal↗
PubMed1999

Radiolabeled antibody therapy of B-cell lymphomas.

Patients with relapsed B-cell lymphomas are currently incurable with conventional doses of chemotherapy or radiotherapy. In recent years, new treatment options have become available for these patients, including the use of chimeric mouse-human anti-CD20 antibodies and radiolabeled anti-CD20 antibodies. The nonradioactive rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) antibody induces remissions in 60% of patients with relapsed follicular lymphomas, including 5% to 10% complete remissions. Anti-CD20 antibodies radiolabeled with iodine 131 and yttrium 90 given at nonmyeloablative doses yield remissions in 75% to 80% of cases, including 35% to 40% complete remissions. High-dose (131)I-anti-B1 antibody with stem cell transplantation generates objective responses in 85% to 90% of cases, including 75% to 80% complete remissions. Although more patients need to be evaluated with a longer follow-up period, radioimmunotherapy appears to be an effective and well-tolerated addition to the oncologists' armamentarium for relapsed lymphomas.

Antibodies, Monoclonal↗
PubMed1999

Overview of the clinical development of rituximab: first monoclonal antibody approved for the treatment of lymphoma.

Rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) is a genetically engineered monoclonal antibody for the treatment of non-Hodgkin's lymphoma. This chimeric mouse/human, immunoglobulin GI kappa anti-CD20 antibody mediates complement-dependent cell lysis and antibody-dependent cellular cytotoxicity. It also has been shown to sensitize chemoresistant human lymphoma cell lines and to induce apoptosis. It was approved by the Food and Drug Administration on November 26, 1997, for the indication of relapsed or refractory, CD-20 positive, B-cell, low-grade or follicular non-Hodgkin's lymphoma Rituximab is the first monoclonal antibody approved for the treatment of cancer and the first single agent approved specifically for therapy of a lymphoma. The recommended dose is rituximab 375 mg/m2 intravenously weekly x4 infusions. Treatment is well tolerated and outpatient therapy is feasible. Adverse events are mostly grades I and 2, occurring primarily with the first infusion. In a phase II single-agent clinical trial, the overall response rate was 50%, with a median time to progression in responders of 10.2 months. In a larger multicenter trial involving 166 patients, the overall response rate was 48% with 6% complete and 42% partial responses. Median time to progression for responders was 13.2 months and median duration of response was 11.6 months. A 40% response rate has been observed on re-treatment with rituximab. Activity also has been seen in patients with bulky disease. Combination studies have been performed with interferon, cyclophosphamide/doxorubicin/vincristine/prednisone, and radioimmunotherapy. Rituximab, the first monoclonal antibody approved for the treatment of cancer, is safe and effective in treating patients with relapsed or refractory, CD-20 positive, B-cell, low-grade or follicular non-Hodgkin's lymphoma.

Antibodies, Monoclonal↗
PubMed1999

Preclinical and phase I and II trials of rituximab.

The CD20 antigen is an attractive target for antibody-directed therapy due to its stable, high-level surface expression on normal and malignant B cells. Rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, and Genentech, Inc, San Francisco, CA) is an anti-CD20 chimeric monoclonal antibody that has shown single-agent activity in phase I and II clinical trials in patients with B-cell non-Hodgkin's lymphoma. This antibody has a long serum half-life and low immunogenicity. Infusional symptoms are common with the initial infusion but rare with subsequent treatments. Temporary B-cell depletion occurs but has not been associated with immunodeficiency. The mechanism of action likely includes both immune-mediated effects and direct effects. The generally mild toxicity profile and excellent single-agent activity provide the rationale for use with or following chemotherapy. Additional studies evaluating these and other combinations are under way.

Antibodies, Monoclonal↗
PubMed1999

Rituximab in indolent lymphoma: the single-agent pivotal trial.

Rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) is a chimeric anti-CD20 monoclonal antibody that targets mature B cells and most B-cell malignancies. Rituximab was the first monoclonal antibody to be approved for therapeutic use for any malignancy. Its approval was based on a single-agent pivotal trial in patients with indolent B-cell lymphoma, in which 166 patients were enrolled from 31 centers in the United States and Canada. The overall results of the trial have been previously reported; additional aspects of the trial (eg, pharmacokinetics) have been reported separately as well. The current report includes an update, expansion, and synthesis of data from the single-agent pivotal trial of rituximab.

Antibodies, Monoclonal↗
PubMed1999

CHOP plus rituximab chemoimmunotherapy of indolent B-cell lymphoma.

Indolent (low-grade) B-cell lymphomas are responsive to single-agent and combination chemotherapy agents, but unfortunately possess an incurable, relapsing nature. Novel agents and innovative treatment approaches need to be evaluated in these patients, with the ultimate goals of maintaining good quality of life and prolonging overall survival. Novel combinations of chemotherapeutic agents, monoclonal antibodies (both unlabeled and radiolabeled), and anti-idiotypic vaccine therapies are currently being evaluated. This article reports on the first successful clinical trial combining a chimeric anti-CD20 monoclonal antibody (rituximab; Rituxan, IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) with standard-dose combination chemotherapy (ie, cyclophosphamide/doxorubicin/vincristine/prednisone [CHOP]) in the treatment of patients with indolent B-cell lymphoma. A 95% overall response (55%, complete remission; 40%, partial remission) rate using strict definitions for complete remission and extensive staging studies was achieved in a 40-patient intent-to-treat group. In addition, seven of seven patients with follicular histologies achieving complete remission also had clearing of BCL-2 (chromosome 14;18 translocation) positivity from blood and marrow by sensitive polymerase chain reaction assay, suggesting the eradication of subclinical minimal residual disease. Based on its single-agent efficacy, excellent toxicity profile, and ability to be successfully combined with combination chemotherapy (ie, CHOP), rituximab is currently undergoing extensive investigation in a large number of worldwide clinical trials to determine its optimal use in the treatment of CD20-positive neoplasms.

Adult↗
PubMed1999

Treatment of plasma cell dyscrasias by antibody-mediated immunotherapy.

The use of serotherapy to treat patients with plasma cell dyscrasias (PCDs) has been sought by us and others. Candidate antigens that have been targeted or proposed for targeting in PCDs include the immunoglobulin idiotype, CD19, CD38, CD54, CD126, HM1.24, and Muc-1 core protein. Unfortunately, many of these antigens are not ideal for use in serotherapy since they are not selectively expressed, are either shed or secreted, or have not been fully characterized. Serotherapy with an anti-CD19 monoclonal antibody (B4) conjugated to a blocked ricin toxin had no significant activity in patients with multiple myeloma (MM). Circulating CD20+ clonotypic B cells have been detected in the circulation of most MM and Waldenstrom's macroglobulinemia (WM) patients. Plasma cells from most WM patients express CD20, but most MM patient plasma cells either lack CD20 or express it weakly. In view of recent successes with anti-CD20-directed serotherapy in other B-cell malignancies, we initiated a phase II trial to study the anti-CD20 monoclonal antibody rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) in patients with MM. We describe two PCD patients (one with WM and one with MM) who responded to therapy. By flow cytometric analysis, CD20+ plasma cells and B cells present in the bone marrow and peripheral blood of a patient with MM disappeared with response to rituximab therapy. However, residual CD20- tumor cells remained in the bone marrow following rituximab therapy, and after 6 months this patient progressed with CD20- myeloma cells. As a potential strategy to overcome this limitation, we demonstrated that interferon-gamma at pharmacologically achievable levels induced CD20 expression on these CD20- plasma cells, consistent with our recent findings that interferon-gamma is a potent inducer of CD20 expression on MM patient plasma cells and B cells. We also characterize a response to rituximab with a decrease in paraprotein and resolution of anemia in a patient with WM whose response to rituximab is ongoing after 19+ months. This preliminary experience supports the potential use of serotherapy targeting CD20 in PCDs. Our studies further suggest that interferon-gamma may enhance CD20 expression on MM plasma cells, thereby increasing their susceptibility to anti-CD20 monoclonal antibody therapies.

Aged↗
PubMed1999

Chronic lymphocytic leukemia.

Research in chronic lymphocytic leukemia (CLL) has undergone a resurgence of interest in the last decade. While it is obvious that most patients with CLL have typical mature B cells, a number of variants such as splenic lymphoma villous lymphocytes, mantle cell leukemia, and prolymphocytic leukemia need to be considered in the differential diagnosis. This can be established by immunophenotype studies and morphology. Cytogenetic abnormalities are emerging as being of interest, with abnormalities in chromosomes 11 and 17 having major prognostic significance. Immune disregulation is complicated in that along with hypergammaglobulinemia and T-cell dysfunction, the emergence of antibodies directed against hematopoietic cells causes autoimmune hemolytic anemia, neutropenia, and thrombocytopenia. A number of prognostic factors are emerging as being more influential in prognosis and stage, such as serum beta2-microglobulin and soluble CD23. Apoptosis dysregulation is a major feature of CLL, and while no clear pattern has emerged, abnormal levels of bcl2 are common in CLL and bcl2 to bax ratios are also commonly disturbed. Bcl1 levels are commonly increased. Treatment has changed radically. The purine analogs have been demonstrated to be the most active group of drugs in CLL. Combinations of purine analogs, such a fludarabine or 2-chlorodeoxyadenosine, with alkylating agents are emerging as new treatments. The most recent development has been the emergence of two monoclonal antibodies, rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA; directed against CD20) and Campath-1H (directed against CD52 in CLL). The activity of rituximab in lymphoma has been less prominent in small lymphocytic lymphoma (the lymphomatous counterpart of CLL) and this has led to dose escalation studies in CLL with a good level of response. Campath-1H is emerging as another major antibody with marked effect against disease, particularly in the blood and bone marrow. Autologous, allogeneic, and mini-transplant are also being explored extensively. The prognosis for patients with CLL is changing as these new treatments become available.

Antibodies, Monoclonal↗
PubMed1999

Stem cell function and engraftment is not affected by "in vivo purging" with rituximab for autologous stem cell treatment for patients with low-grade non-Hodgkin's lymphoma.

The chimeric anti-CD20 monoclonal antibody rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) has recently been approved by the US Food and Drug Administration as single-agent treatment of relapsed/refractory low-grade or follicular non-Hodgkin's lymphoma. Initial results from the pivotal clinical trial revealed that response rates to rituximab were higher in patients who previously had high-dose therapy and autologous stem cell transplantation. We have initiated a clinical trial that combines the use of rituximab with high-dose chemotherapy followed by autologous stem cell transplantation for patients with chemosensitive relapsed follicular small cleaved or mantle cell lymphoma. A unique feature of this study is that in addition to eight maintenance infusions of rituximab after autologous stem cell transplantation, patients also received rituximab 375 mg/m2 2 days before a granulocyte colony-stimulating factor-mobilized stem cell collection as "in vivo purge." We report on preliminary results demonstrating the safety and efficacy of the in vivo purge on 10 patients undergoing stem cell mobilization, nine of whom have already undergone transplantation. The peripheral blood CD34+ counts were 14.92 and 20 x 10(6)/L on day 4 and day 5, respectively, of the stem cell mobilization with granulocyte colony-stimulating factor. This compares with 11.7 and 11.8 x 10(6)/L, respectively, for the control population. The median CD34 stem cell yield in the graft collection was 3.7 x 10(6)/kg in patients receiving rituximab in vivo purge compared with 3.1 x 10(6)/kg in the control population. The target stem cell collection was successfully collected in six of 10 patients in a 1-day single large-volume leukapheresis collection, while two patients required 2 days and the last two patients required 3 days. Functional assays revealed the stem cell colony-forming unit-granulocyte monocyte and burst-forming unit-erythrocyte to be 55 and 44 colonies per plate, respectively, for the patients receiving the in vivo rituximab purge. This compares favorably with 37 and 38.5 colonies per plate, respectively, for the control population. Neutrophil engraftment took a median of 11 days for both cohorts; platelet independence was achieved in 8 days compared with 10 days for the control population. The median number of platelet transfusions was two for patients receiving rituximab and 2.5 for the control group. Assessment of serum cytokines immediately before the rituximab infusion during the stem cell mobilization and immediately after revealed a twofold to sevenfold increase in interleukin-1beta, tumor necrosis factor-alpha, and interleukin-6. The polymerase chain reaction analysis for minimal residual disease in stem cell collections and in peripheral blood and bone marrow samples of these patients will help to determine the efficacy of rituximab in vivo purge on disease progression.

Adult↗
PubMed2000

State-of-the-art chemotherapy for advanced breast cancer.

Several recent advances have led to accelerated progress in breast cancer therapy. The development of new drugs with novel mechanisms of action, such as the taxanes, or oral bioavailability, such as capecitabine, has expanded the horizons of available chemotherapy. The use of tumor-related proteins or genes as markers of sensitivity or resistance to systemic therapy may allow for more predictable outcomes. Finally, the emergence of biological therapies such as the HER2/neu monoclonal antibody trastuzumab (Herceptin; Genentech, Inc, So. San Francisco, CA) represents an exciting new direction that opens doors to new concepts in antitumor therapy. This report will review the most exciting possibilities for expanding the field of breast cancer management.

Antibiotics, Antineoplastic↗
PubMed2000

Biological rationale for HER2/neu (c-erbB2) as a target for monoclonal antibody therapy.

The physical characteristics of tumor antigens that would make the most ideal targets for antibody therapeutics include cell surface expression; high, stable expression levels in tumor cells; low or absent expression in normal tissues; lack of a soluble form of the antigenic target; and lack of internalization of the antigen/antibody complex. HER2/neu is a 185-kd surface membrane protein that is overexpressed in approximately 25% of human breast cancers due to amplification of the HER2 gene. Overexpression of the gene results in ligand-independent activation of HER2 kinase, causing mitogenic signal transduction and increased cell proliferation. Consequently, patients with this alteration have a worse clinical prognosis. Trastuzumab (Herceptin; Genentech, Inc, So. San Francisco, CA), a humanized anti-HER2 monoclonal antibody, has significant clinical activity against metastatic breast cancers with HER2/neu overexpression, despite the fact that the p185HER2 protein product lacks some of the ideal characteristics of tumor antigens listed above. We propose that the efficacy of trastuzumab may be explained on the basis of its effects on signal transduction, which is independent from its immune mechanism(s) of action. Furthermore, trastuzumab is synergistic with some chemotherapeutic drugs, resulting in improved therapeutic efficacy. Thus, in the case of trastuzumab, a clear distinction may be drawn between the use of monoclonal antibodies as immuneactive agents and their use to achieve a desired cellular/biochemical activity.

Antibodies, Monoclonal↗
PubMed2000

Clinical trials of single-agent trastuzumab (Herceptin).

The HER2 gene (also known as neu and as c-erb-B2) encodes a 185-kd transmembrane glycoprotein receptor with intrinsic tyrosine kinase activity. HER2 is overexpressed in 25% to 30% of human breast cancers, plays a role in the pathogenesis of breast cancer, and predicts for a worse prognosis in patients with metastatic disease. Trastuzumab (Herceptin; Genentech, Inc, So. San Francisco, CA), a humanized monoclonal antibody that targets the HER2 oncogene receptor, was shown to be active in preclinical models. In initial phase I clinical trials, trastuzumab was found to be safe and to exhibit dose-dependent pharmacokinetics. Three phase II studies of single-agent trastuzumab, which was administered weekly in the outpatient setting, have now been conducted in patients with HER2-overexpressing metastatic breast cancer. In the initial phase II study, the response rate was 11% in a heavily pretreated patient population. In a pivotal follow-up study of single-agent trastuzumab, more than 200 patients who had received at least one prior chemotherapeutic regimen for metastatic disease were entered. Despite a number of unfavorable baseline characteristics, the response rate reported by an independent response evaluation committee was 15%. A more recent study in previously untreated patients has shown a 23% response rate. The median duration of response in these trials has ranged from 6.6 to 9.1 months. In these three phase II studies, trastuzumab has been shown to be safe. The most clinically significant adverse event has been cardiac dysfunction syndrome, which occurred in less than 5% of patients. Trastuzumab is not associated with the other commonly observed side effects of chemotherapy, such as alopecia, mucositis, and neutropenia. The results from these studies demonstrate that trastuzumab is active and safe in patients with metastatic HER2-overexpressing breast cancer.

Animals↗
PubMed2000

Current and planned clinical trials with trastuzumab (Herceptin).

Trastuzumab (Herceptin; Genentech, Inc, So. San Francisco, CA) is a high-affinity, humanized anti-HER2 antibody that has shown benefit in the therapy of patients with metastatic HER2-overexpressing breast cancer. Results from initial clinical trials of trastuzumab as a single agent or in combination with chemotherapy established important guidelines for the therapy of HER2-positive tumors, but represent an early phase of clinical development. Preclinical studies have shown additive and synergistic effects of trastuzumab when given in combination with several chemotherapeutic agents, and a series of clinical trials exploring these new combinations is under way or will be started shortly. Substantial effort will be directed toward promising schedules and combinations, such as weekly paclitaxel with trastuzumab or combinations of platinum, taxanes, and trastuzumab. Due to the unexpected cardiac toxicity observed with the combination of doxorubicin plus trastuzumab, new studies will be designed to prospectively assess cardiac function and will incorporate anthracyclines with less cardiotoxicity, such as liposomal doxorubicin. Combination studies are not limited to cytotoxic agents, as laboratory and clinical data have demonstrated that HER2 overexpression results in resistance to hormonal therapy. Therefore, a series of studies combining hormonal treatments with trastuzumab is being considered. Finally, the integration of trastuzumab into the adjuvant and neoadjuvant settings will be studied by United States and European cooperative groups.

Antibiotics, Antineoplastic↗
PubMed2000

Rituximab as first-line systemic therapy for patients with low-grade lymphoma.

Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA and IDEC Pharmaceutical Corporation, San Diego, CA), the first monoclonal antibody available for the systemic treatment of cancer, yields a 48% response rate in patients with refractory low-grade non-Hodgkin's lymphoma. This preliminary report describes the use of rituximab, instead of standard chemotherapy, in 39 previously untreated patients with stages II-IV low-grade non-Hodgkin's lymphoma All patients received rituximab 375 mg/m2 by intravenous infusion for 4 consecutive weeks and were evaluated for response at week 6. Patients with stable disease or an objective response received repeat 4-week courses at 6-month intervals, for a maximum of four treatment cycles. At initial evaluation for response at week 6, 21 of 39 patients (54%) had objective responses and 14 (36%) had stable disease or a minor response. Response rates were similar in patients with follicular and small lymphocytic lymphoma (52% v 57%, respectively). Seven additional responses were reported either before or after the second course. Currently, the overall response rate is 72%, with 18% complete responses. The progression-free survival rate at 1 year is 77%. Treatment was well tolerated. The high level of activity suggests that initial treatment with rituximab is a reasonable option in this group of patients, and that repeat maintenance courses at 6-month intervals are feasible and well tolerated. Further follow-up evaluation is necessary to determine the merits of this approach compared with traditional chemotherapeutic treatment.

Adult↗
PubMed2000

Chemotherapy sensitization by rituximab: experimental and clinical evidence.

For most lymphomas, chemotherapy is palliative because of an inability to overcome drug resistance within the lymphoma cells and attempts at overcoming specific drug resistance mechanisms, such as multidrug resistance, have had limited success. However, accumulating evidence suggests that the ability to activate apoptotic pathways may be an important determinant of chemotherapy sensitivity and presents a potentially important new therapeutic strategy. Studies have shown that distinct cellular thresholds exist for apoptosis, and it is likely that multiple developmental and environmental factors converge in a dynamic process to regulate this set point. If the threshold for inducing apoptosis is limiting, then strategies to modulate these pathways may profoundly enhance the efficacy of cytotoxic therapy. Monoclonal antibodies against the CD20 receptor have been shown to directly induce apoptosis and may serve to modulate the threshold for chemotherapy-induced apoptosis. Recent clinical studies of the monoclonal antibody, rituximab (Rituxan; Genentech, Inc, South San Francisco, CA and IDEC Pharmaceutical Corporation, San Diego, CA), and combination chemotherapy have produced unexpectedly high rates of response and progression-free survival, suggesting rituximab improves the efficacy of chemotherapy. Taken together, the results from in vitro and clinical studies suggest that rituximab may modulate the sensitivity of B-cell lymphomas to chemotherapy.

Antibodies, Monoclonal↗
PubMed2000

Safety of fludarabine, mitoxantrone, and dexamethasone combined with rituximab in the treatment of stage IV indolent lymphoma.

Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA and IDEC Pharmaceutical Corporation, San Diego, CA) is an effective agent for the treatment of CD20-positive B-cell lymphomas. Because its toxicities are minimal and do not overlap with the toxicities of standard chemotherapy, it is an appealing agent to use in combination with chemotherapy. Moreover, there is evidence for synergy between rituximab and some chemotherapeutic agents. The combination of fludarabine/ mitoxantrone/dexamethasone (FND) has been a well-tolerated and effective regimen for the treatment of indolent lymphomas. When given together with prophylaxis for Pneumocystis carinii, infectious complications with FND have been modest. We report on preliminary safety data using FND in conjunction with rituximab, along with maintenance alpha interferon. Toxicity has been modest. The concurrent use of rituximab with FND modestly increases neutropenia, but has not resulted in any change in the pattern of infectious or other toxicity that occurs with FND alone.

Antibodies, Monoclonal↗