Multicenter phase II study of iodine-131 tositumomab for chemotherapy-relapsed/refractory low-grade and transformed low-grade B-cell non-Hodgkin's lymphomas

Clinical syndromes of transformation in clonal hematologic disorders

The majority of clonal hematologic syndromes, including lymphoproliferative, myeloproliferative, and myelodysplastic disorders, tend to undergo transformation. However, the frequency of transformation varies widely. For example, transformation is almost invariable in chronic myelogenous leukemia, but it is infrequent in other myeloproliferative disorders. Similarly, transformation occurs in approximately 33% of follicular lymphomas but less commonly in other lower-grade lymphomas. At a genetic level, although some secondary lesions are seen across the spectrum of transformation syndromes (such as loss of function of p53 and p15/p16), there is considerable intra- and interdisease variability, with no common denominator. This review of the literature will discuss these transformations, noting their frequency, pathologic changes observed, clinical syndromes described, underlying genetic correlates, and prognostic and therapeutic implications.

Efficacy and toxicity of bendamustine in patients with relapsed low-grade non-Hodgkin's lymphomas

Low-grade non-Hodgkin's lymphomas (NHL) are very sensitive to a broad range of chemotherapeutic and biological agents. Relapses, however, occur even after aggressive cytostatic combinations in first-line therapy. Therefore, effective and well-tolerated salvage therapies are very important. In this single-institution trial, the efficacy and toxicity of bendamustine in the treatment of relapsed low-grade NHL was investigated. Fifty-eight patients with low-grade NHL pretreated with different cytostatic regimens were included. All patients received bendamustine at 120 mg/m(2) as a 1-h infusion on 2 consecutive days. The treatment was repeated every 3 weeks until complete remission (CR), partial remission (PR) or stable disease (SD) was confirmed on two consecutive cycles. Efficacy and toxicity were evaluated in 52 patients: CR was induced in 11%, PR in 62% and SD in another 10% of the patients. No response to treatment was seen in 17%. The median duration of remission was 16 months and the median survival time was 36 months. Side effects were generally mild, and restricted to myelosuppression, gastrointestinal toxicity and allergic reactions. Bendamustine proved to be very effective and was well tolerated in pretreated patients with relapsed or primary resistant low-grade NHL.

Pivotal study of iodine I 131 tositumomab for chemotherapy-refractory low-grade or transformed low-grade B-cell non-Hodgkin's lymphomas

PURPOSE

To evaluate the efficacy and safety of tositumomab and iodine I 131 tositumomab (Bexxar; Corixa Corp, Seattle, WA, and GlaxoSmithKline, Philadelphia, PA) in patients with chemotherapy-refractory low-grade or transformed low-grade non-Hodgkin's lymphoma (NHL) and to compare its efficacy to the patients' last qualifying chemotherapy (LQC) regimens.

PATIENTS AND METHODS

Sixty patients who had been treated with at least two protocol-specified qualifying chemotherapy regimens and had not responded or progressed within 6 months after their LQC were treated with a single course of iodine I 131 tositumomab.

RESULTS

Patients had received a median of four prior chemotherapy regimens. A partial or complete response (CR) was observed in 39 patients (65%) after iodine I 131 tositumomab, compared with 17 patients (28%) after their LQC (P <.001). The median duration of response (MDR) was 6.5 months after iodine I 131 tositumomab, compared with 3.4 months after the LQC (P <.001). Two patients (3%) had a CR after their LQC, compared with 12 (20%) after iodine I 131 tositumomab (P <.001). The MDR for CR was 6.1 months after the LQC and had not been reached with follow-up of more than 47 months after iodine I 131 tositumomab. An independent review panel verified that 32 (74%) of the 43 patients with nonequivalent durations of response (> 30 days difference) had a longer duration of response after iodine I 131 tositumomab (P <.001). Only one patient was hospitalized for neutropenic fever. Five patients (8%) developed human antimurine antibodies, and one (2%) developed an elevated TSH level after treatment. Myelodysplasia was diagnosed in four patients in follow-up.

CONCLUSION

A single course of iodine I 131 tositumomab was significantly more efficacious than the LQC received by extensively pretreated patients with chemotherapy-refractory, low-grade, or transformed low-grade NHL and had an acceptable safety profile.

Humanization and characterization of the anti-HLA-DR antibody 1D10

1D10 is a previously described antibody that binds to cells from a majority of B-cell malignancies. The current studies were designed to further evaluate the antigen specificity of 1D10 and its potential as an immunotherapeutic agent. Studies with transfectants and immunoprecipitation demonstrated that 1D10 recognizes some, but not all, of the human HLA-DR beta chains. Both normal and malignant B cells can express the 1D10 antigen. A humanized version of 1D10 was produced using CDR grafting. The resulting antibody has an affinity that is similar to that of the parental murine antibody. In addition, the humanized antibody is capable of inducing complement-mediated cytotoxicity, antibody-dependent cell cytotoxicity, and direct apoptosis of 1D10-expressing B cells. Based on these in vitro anti-tumor activities, we conclude humanized 1D10 deserves further evaluation as an immunotherapeutic agent.

Human therapeutic antibodies

The development of genetic engineering technologies has today advanced to the point where the generation of high-affinity human antibodies against therapeutic targets is not a major hurdle. Rather, it is the selection of target molecules in, for example, cancer therapy that poses a challenge. Targets that are not merely passive acceptors but those that signal into the cell are preferred. Recent advances in the clinical use of antibody-based therapy--such as anti-CD20 (rituximab) for the treatment of non-Hodgkin's lymphoma and anti-tumour-necrosis-factor-alpha for Crohn's disease--as well as novel antibody designs and improved understanding of the mode of action of current antibodies lend great hope to the future of this therapeutic approach.

A randomized controlled trial to evaluate the role of interferon as initial and maintenance therapy in patients with follicular lymphoma

The purpose of this study was to evaluate the role of interferon as initial and maintenance therapy in patients with newly diagnosed follicular lymphoma. Between 1984 and 1994, 204 patients with newly diagnosed Stage III or Stage IV follicular lymphoma were randomized to receive either, Chlorambucil (CB): 10 mg daily for 6 weeks, followed by a 2-week interval, with 3 subsequent 2-week treatment periods at the same dose, separated by 2-week intervals, or, CB given concurrently with interferon (IFN). IFN was given at a dose of 3 x 10(6)units thrice weekly, subcutaneously, throughout the 18-week treatment period. Responding patients were subsequently randomized to receive maintenance IFN at the dose and schedule described above, or to expectant management. The overall response rate was 161/204 (78%), complete remission being achieved in 24% of patients. Neither the addition of IFN to the initial treatment, nor the use of maintenance IFN influenced response rate, remission duration or survival. This study was undertaken to determine whether IFN, given in combination with, and then subsequent to, CB would alter the clinical course of patients with follicular lymphoma. Disappointingly, this objective was not achieved, no advantage having been demonstrated for the addition of IFN.

Radioimmunotherapy with iodine-131 tositumomab in patients with low-grade non-Hodgkin's B-cell lymphoma does not induce loss of acquired humoral immunity against common antigens

Thirty-one previously untreated patients with follicular low-grade B-cell non-Hodgkin's lymphoma expressing the CD20 antigen were treated with iodine-131 tositumomab therapy between 1996 and 1998. The therapy led to a temporary depletion of peripheral blood B-lymphocytes. Recovery of B-cells occurred in most cases by 3 to 6 months and in all patients by 12 months posttherapy. A temporary decline in T-cell subpopulations, but no reduction in serum immunoglobulin levels, could be observed. ELISA techniques were used to detect specific antibodies against rubella, mumps, varicella zoster, measles, and tetanus. Almost all patients remained seropositive against the different antigens during the 1- to 2-year follow-up. No significant reduction in antibody concentrations to tetanus or measles could be detected. The data show that acquired humoral immunity against common antigens appears to be preserved despite a temporary loss of B-lymphocytes.

Biodistribution and dosimetry results from a phase III prospectively randomized controlled trial of Zevalin radioimmunotherapy for low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma

Radiation dosimetry studies were performed in patients with non-Hodgkin's lymphoma (NHL) treated with 90Y Zevalin (90yttrium ibritumomab tiuxetan, IDEC-Y2B8) on a Phase III open-label prospectively randomized multicenter trial. The trial was designed to evaluate the efficacy and safety of 90Y Zevalin radioimmunotherapy compared to rituximab (Rituxan, MabThera) immunotherapy for patients with relapsed or refractory low-grade, follicular, or transformed NHL. An important secondary objective was to determine if radiation dosimetry prior to 90Y Zevalin administration is required for safe treatment in this patient population.

METHODS

Patients randomized into the Zevalin arm were given a tracer dose of 5 mCi (185 MBq) (111)In Zevalin (111indium ibritumomab tiuxetan) on Day 0, evaluated with dosimetry, and then administered a therapeutic dose of 0.4 mCi/kg (15 MBq/kg) 90Y Zevalin on Day 7. Both Zevalin doses were preceded by an infusion of 250 mg/m(2) rituximab to clear peripheral B-cells and improve Zevalin biodistribution. Following administration of (111)In Zevalin, serial anterior and posterior whole-body scans were acquired and blood samples were obtained. Residence times for 90Y were estimated for major organs, and the MIRDOSE3 computer software program was used to calculate organ-specific and total body radiation absorbed dose. Patients randomized into the rituximab arm received a standard course of rituximab immunotherapy (375 mg/m(2) weekly x 4).

RESULTS

In a prospectively defined 90 patient interim analysis, the overall response rate was 80% for Zevalin vs. 44% for rituximab. For all patients with Zevalin dosimetry data (N=72), radiation absorbed doses were estimated to be below the protocol-defined upper limits of 300 cGy to red marrow and 2000 cGy to normal organs. The median estimated radiation absorbed doses were 71 cGy to red marrow (range: 18-221 cGy), 216 cGy to lungs (94-457 cGy), 532 cGy to liver (range: 234-1856 cGy), 848 cGy to spleen (range: 76-1902 cGy), 15 cGy to kidneys (0.27-76 cGy) and 1484 cGy to tumor (range: 61-24274 cGy). Toxicity was primarily hematologic, transient, and reversible. The severity of hematologic nadir did not correlate with estimates of effective half-life (half-life) or residence time of 90Y in blood, or radiation absorbed dose to the red marrow or total body.

CONCLUSION

90Y Zevalin administered to NHL patients at non-myeloablative maximum tolerated doses delivers acceptable radiation absorbed doses to uninvolved organs. Lack of correlation between dosimetric or pharmacokinetic parameters and the severity of hematologic nadir suggest that hematologic toxicity is more dependent on bone marrow reserve in this heavily pre-treated population. Based on these findings, it is safe to administer 90Y Zevalin in this defined patient population without pre-treatment (111)In-based radiation dosimetry.

Apoptosis-related gene and protein expression in human lymphoma xenografts (Raji) after low dose rate radiation using 67Cu-2IT-BAT-Lym-1 radioimmunotherapy

Despite low radiation dose rates, radioimmunotherapy (RIT) has proven particularly effective in the treatment of malignancies, such as lymphoma. Apoptosis has been suggested to be a major mechanism for cell death from continuous low-dose rate radiation from radioimmunotherapy. The goal of this study was to examine Raji lymphoma xenografts for induction of apoptosis and modulation of apoptosis-related gene and protein expression in response to 67Cu-2IT-BAT-Lym-1 RIT. In preclinical and clinical trials, 67Cu-2IT-BAT-Lym-1 has shown an exceptionally long tumor residence time associated with substantial cumulated radiation doses. The Raji model mirrors human lymphomas that have mutant p53 and increased BCL2 expression. Untreated athymic BALB/c nu/nu mice and mice treated with 400 micrograms Lym-1, or 335-500 microCi 67Cu on less than 400 micrograms Lym-1 antibody, were observed for toxicity and response over 84 days. Subgroups of 4-5 mice were sacrificed at 3, 6 and 24 h after therapy so that tumors could be examined for poly(ADP-ribose) polymerase (PARP) and DNA ladder evidence for apoptosis and for BCL2, p53, p21, GADD45, TGF-beta 1 and c-MYC gene and protein expression. Untreated tumors had little evidence of apoptosis and Lym-1 had no effect on apoptosis or gene expression. 67Cu-2IT-BAT-Lym-1 RIT induced an overall response rate of 50% with tolerable toxicity, and 29% of the tumors were cured at cumulated tumor radiation doses of about 1800 cGy. Apoptosis was greatly increased in the RIT treated Raji xenografts as evidenced by cleavage of PARP to the characteristic 85 kD fragment at 3 and 6 h and by the DNA cleavage pattern. BCL2 gene and protein expression were substantially decreased at 3 and 24 h, respectively, after 67Cu-2IT-BAT-Lym-1 RIT despite only modest cumulated radiation doses (56 cGy at 3 h). Evidence for apoptosis preceded tumor regression by 4-6 days. In these therapy-resistant, human lymphoma tumors treated with 67Cu-2IT-BAT-Lym-1, apoptosis was convincingly demonstrated to be a major mechanism for the effectiveness of RIT and occurred by p53-independent mechanisms.

Serum nm23-H1 protein as a prognostic factor for indolent non-Hodgkin's lymphoma

Standard chemotherapy has been ineffective for improving the poor 10-year survival rate of patients with indolent lymphoma. However, a wider choice of therapeutic modalities has become recently available, including immunotherapy with monoclonal antibodies and allogeneic peripheral blood stem cell transplantation. Accordingly, a sensitive prognostic indicator is required to identify high-risk patients and to help design new therapeutic approaches for them. We previously reported that the serum nm23-H1 protein level was an independent prognostic factor for aggressive lymphoma. The present study was performed to assess the clinical implications of this protein on indolent lymphoma and whether it can be used to classify the aggressiveness of the disease in order to assist in the individualization of therapy. A total of 130 patients with indolent lymphoma were enrolled in this multicenter study. The serum nm23-H1 protein level was significantly higher in patients with indolent lymphoma than in a normal control group. In addition, indolent lymphoma patients with higher nm23-H1 levels had worse overall and progression-free survival rate than those with lower nm23-H1 levels. Therefore, nm23-H1 in serum may be useful for identifying a distinct group of patients at high risk.

Monoclonal antibody therapy for lymphoma: an update

PURPOSE

The purpose of this article is to review the historical development and recent advances in the application of monoclonal antibodies for the treatment of lymphoma.

OVERVIEW

The history of clinical applications of monoclonal antibodies has been intertwined with that of lymphomas. The first report of a complete remission in 1981 described a patient with follicular lymphoma who was treated with a murine anti-idiotype antibody. Later that decade there appeared additional encouraging reports of radiolabeled monoclonal antibodies, immunotoxins, and other antibodies with antitumor effects against lymphoma and chronic lymphocytic leukemia. Monoclonal antibodies as a treatment of malignancy became reality in late 1997 when the US Food and Drug Administration approved the anti-CD20 chimeric monoclonal antibody rituximab for the treatment of B-cell lymphoma. Since that time an anti-CD25 monoclonal antibody (dacliximab) and an anti-CD25 immunotoxin fusion product (denileukin diftitox) have become clinically available. Several radio- labeled antibodies, including the murine anti-CD20 products (131)I-tositumomab and (90)Y-ibritumomab tiuxetan, are in advanced stages of clinical testing as are other unlabeled monoclonal antibodies with antilymphoma activity. Other antilymphoma immunotoxins that react with CD25, CD19, and CD22 also have shown promise.

CLINICAL IMPLICATIONS

The therapeutic arsenal against lymphoma has been significantly changed by the addition of these antibody products that are active as single agents, and are synergistic, additive, or both with other antilymphoma treatments.

Monoclonal antibodies and autologous stem cell transplantation for lymphoma

The introduction of monoclonal antibodies into the clinic has paved the way for new approaches to stem cell transplantation for patients with lymphoma. These approaches include the development of new high-dose regimens with radiolabeled antibodies, in vivo purging techniques with the unlabeled antibodies, and post-transplant adjuvant immunotherapy. Numerous trials have demonstrated the feasibility of these approaches. However, questions remain regarding the application of these antibodies including the ultimate efficacy. The recent results of the incorporation of monoclonal antibodies into stem cell transplantation and current research directions are reviewed.

Monoclonal antibody therapy in lymphoid malignancies

The concept of targeted therapy for patients with advanced cancer has intrigued researchers for many years. The lymphoid malignancies are particularly good candidates for this therapeutic approach, due to the identification of multiple lymphocyte-specific antigens. The recent introduction of rituximab marks the beginning of a new era in the treatment of lymphoid malignancies. Rituximab is one of the most active single agents for patients with refractory indolent lymphoma, producing response rates of approximately 50%, with low toxicity and a brief duration of treatment. Additional uses of rituximab are being evaluated in ongoing clinical trials, and are briefly reviewed. As a first-line agent, responses of approximately 70% are produced in patients with indolent lymphoma, with minimal toxicity. A substantial percentage of patients can be successfully retreated with rituximab, with second remission durations longer than the first remission (14-16 months versus 12 months). Multiple combination regimens using rituximab plus chemotherapy are also being evaluated. Although the role of these combined approaches is incompletely defined, high complete response rates can be obtained, with a higher rate of molecular complete remission (i.e., eradication of detectable bcl-2 rearrangements) than has been observed in patients receiving chemotherapy alone. Rituximab is also being evaluated in other CD20(+) lymphoid malignancies including large-cell lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, and Waldenstrom's macroglobulinemia. Within the next 12 months, several additional monoclonal antibodies will be available for the treatment of lymphoid malignancies. These include the radioimmunoconjugates tositumomab (Bexxar) and ibritumomab (Zevalin), as well as Campath-1H (anti-CD52) monoclonal antibody. Early clinical data with each of these agents are also briefly reviewed.

Immunotherapy of Non-Hodgkin's lymphomas

Recent years have witnessed the development of a variety of promising immunotherapies for treating patients with non-Hodgkin's lymphomas. Foremost among these advances is the exciting success of monoclonal antibodies directed against lymphocyte surface antigens. Rituximab is a chimeric (human-mouse) anti-CD20 antibody that induces responses in approximately half of the patients with relapsed indolent lymphomas and a third of patients with relapsed aggressive lymphomas when used as a single agent. Response rates appear even higher (up to 70%) for newly diagnosed patients treated with Rituximab monotherapy. Other promising antibodies for treatment of B cell malignancies include epratuzumab (anti-CD22), CAMPATH-1H (anti-CD52w), and Hu1D10 (anti-class II HLA). Even more exciting than antibody monotherapy is the prospect of combination antibody therapy (e.g. rituximab + epratuzumab) or combination chemotherapy and antibody therapy. In this regard, a recent phase III randomized trial from the GELA group in France demonstrated statistically significantly superior complete and overall response rates and superior event-free and overall survivals for elderly patients with newly diagnosed diffuse aggressive B cell lymphomas treated with CHOP + rituximab compared with CHOP alone. Confirmatory cooperative group trials combining chemotherapy with antibody therapies are currently underway. Another approach to augment the efficacy of antibodies is to deploy them in radiolabeled form. Iodine-131, Yttrium-90, and Copper-67 labeled monoclonal antibodies targeting CD-20, CD-22, HLA class II, and other cell surface antigens have been tested and demonstrate higher overall response rates (50-80%) and complete response rates (20-40%) than unlabeled antibodies. Pilot studies combining radiolabeled antibodies with either standard dose chemotherapy or myeloablative chemoradiotherapy with stem cell transplantation also appear very promising. Lymphoma vaccines have also produced very encouraging results in single institution studies at Stanford and the National Cancer Institute, with responding patients demonstrating superior event-free and overall survival than historical controls. Phase III randomized trials of idiotype vaccines are currently underway and novel new vaccine approaches are also being tested.

Elevated soluble MUC1 levels and decreased anti-MUC1 antibody levels in patients with multiple myeloma

Soluble MUC1 (sMUC1) levels are elevated in many MUC1+cancers. We and others have shown that MUC1 is expressed on multiple myeloma (MM) plasma cells and B cells. In this study, we measured sMUC1 levels in bone marrow (BM) plasma from 71 MM patients and 21 healthy donors (HDs), and in peripheral blood (PB) plasma from 42 MM patients and 13 HDs using an immunoassay that detects the CA27.29 epitope of MUC1. sMUC1 levels were found to be significantly greater (mean 31.76 U/mL, range 5.69 to 142.48 U/mL) in MM patient BM plasma versus HD BM plasma (mean 9.68 U/mL, range 0.65 to 39.83 U/mL) (P &lt; .001). Importantly, BM plasma sMUC1 levels were related to tumor burden because sMUC1 levels were significantly higher for MM patients with active disease (34.62 U/mL, range 5.69 to 142.48 U/mL) versus MM patients with minimal residual disease (16.16 U/mL, range 5.7 to 56.68 U/mL) (P = .0026). sMUC1 levels were also elevated in the PB plasma of MM patients (32.79 U/mL, range 4.15 to 148.84 U/mL) versus HDs (18.47 U/mL, range 8.84 to 42.49) (P = .0052). Lastly, circulating immunglobulin M (IgM) and IgG antibodies to MUC1 were measured in 114 MM patients and 31 HDs, because natural antibodies to MUC1 have been detected in patients with other MUC1-bearing malignancies. These studies demonstrated lower levels of circulating IgM (P &lt; .001) and IgG (P = .078) antibodies to MUC1 in MM patients compared with HDs. Our data therefore show that in MM patients, sMUC1 levels are elevated and correlate with disease burden, whereas anti-MUC1 antibody levels are decreased.

Elevated soluble MUC1 levels and decreased anti-MUC1 antibody levels in patients with multiple myeloma

Soluble MUC1 (sMUC1) levels are elevated in many MUC1+cancers. We and others have shown that MUC1 is expressed on multiple myeloma (MM) plasma cells and B cells. In this study, we measured sMUC1 levels in bone marrow (BM) plasma from 71 MM patients and 21 healthy donors (HDs), and in peripheral blood (PB) plasma from 42 MM patients and 13 HDs using an immunoassay that detects the CA27.29 epitope of MUC1. sMUC1 levels were found to be significantly greater (mean 31.76 U/mL, range 5.69 to 142.48 U/mL) in MM patient BM plasma versus HD BM plasma (mean 9.68 U/mL, range 0.65 to 39.83 U/mL) (P < .001). Importantly, BM plasma sMUC1 levels were related to tumor burden because sMUC1 levels were significantly higher for MM patients with active disease (34.62 U/mL, range 5.69 to 142.48 U/mL) versus MM patients with minimal residual disease (16.16 U/mL, range 5.7 to 56.68 U/mL) (P = .0026). sMUC1 levels were also elevated in the PB plasma of MM patients (32.79 U/mL, range 4.15 to 148.84 U/mL) versus HDs (18.47 U/mL, range 8.84 to 42.49) (P = .0052). Lastly, circulating immunglobulin M (IgM) and IgG antibodies to MUC1 were measured in 114 MM patients and 31 HDs, because natural antibodies to MUC1 have been detected in patients with other MUC1-bearing malignancies. These studies demonstrated lower levels of circulating IgM (P < .001) and IgG (P = .078) antibodies to MUC1 in MM patients compared with HDs. Our data therefore show that in MM patients, sMUC1 levels are elevated and correlate with disease burden, whereas anti-MUC1 antibody levels are decreased.

Treatment of non-Hodgkin lymphoma

Preliminary results of new therapies in the areas of cytotoxic agents and immunotherapy for advanced indolent lymphomas have been encouraging. Long-term follow-up on high-dose therapy suggests a potential role for this modality in this group of lymphomas. In aggressive lymphomas, CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) continues to hold ground as first-line therapy when compared against other regimens. Several studies reinforce past findings that patients with chemosensitive relapse are better candidates for high-dose therapy. In relapsed or refractory disease, selected compounds appear to have activity as single agents and others have shown activity in combination therapy. Despite high treatment-related mortality rates, allogeneic transplantation in relapsed aggressive lymphoma warrants further investigation. Last, as patients are surviving longer, complications of therapy are having to be addressed.

Emerging Therapies: Spectrum of Applications of Monoclonal Antibody Therapy

This article focuses on the recent dramatic advances in the applications of monoclonal antibody therapy to hematopoietic and neoplastic disease. The increase in the understanding of the role of growth factors and their receptors in the pathogenesis of malignancy and other undesirable hematological events taken in conjunction with the ability to produce humanized chimeric monoclonal antibodies to these targets is providing a new perspective for the treatment of leukemia, lymphoma and breast cancer, autoimmune disease and for prevention of ischemic complications. Dr. Waldmann describes approaches targeting the Her2/neu and the II-2/IL-15 receptor systems. The Her2/neu receptor is overexpressed in select breast, ovarian, gastric and pancreatic neoplasms. The use of trastuzumab (Herceptin) in the treatment of patients with breast cancer whose tumors overexpress this receptor are reviewed. The IL-2 receptor (Tac) is expressed on select malignant cells (adult T cell leukemia, hairy cell leukemia) and activated T cells involved in autoimmune disease and organ rejection. Humanized anti-Tac alone (daclizumab, Zenapax) or armed with toxins or radionuclides have been used successfully in the treatment of leukemia. Dr. Levy updates the experience with rituximab targeting CD20 on B cell lymphomas and reviews the antibodies to CD3, CD22, CD33, CD52, HLA-DR β chain and HLA-D currently in or proposed for clinical trials, including radiolabelled antibodies. In the last section, Dr. Coller reviews the therapeutic results achieved with abciximab (ReoPro), an antagonist of platelet receptor GPIIbIIIa for the prevention of restenosis in percutaneous coronary interventions and the treatment of unstable angina. The mechanism of action, pharmacology and safety and efficacy of abciximab are reviewed.

Emerging Therapies: Spectrum of Applications of Monoclonal Antibody Therapy

This article focuses on the recent dramatic advances in the applications of monoclonal antibody therapy to hematopoietic and neoplastic disease. The increase in the understanding of the role of growth factors and their receptors in the pathogenesis of malignancy and other undesirable hematological events taken in conjunction with the ability to produce humanized chimeric monoclonal antibodies to these targets is providing a new perspective for the treatment of leukemia, lymphoma and breast cancer, autoimmune disease and for prevention of ischemic complications. Dr. Waldmann describes approaches targeting the Her2/neu and the II-2/IL-15 receptor systems. The Her2/neu receptor is overexpressed in select breast, ovarian, gastric and pancreatic neoplasms. The use of trastuzumab (Herceptin) in the treatment of patients with breast cancer whose tumors overexpress this receptor are reviewed. The IL-2 receptor (Tac) is expressed on select malignant cells (adult T cell leukemia, hairy cell leukemia) and activated T cells involved in autoimmune disease and organ rejection. Humanized anti-Tac alone (daclizumab, Zenapax) or armed with toxins or radionuclides have been used successfully in the treatment of leukemia. Dr. Levy updates the experience with rituximab targeting CD20 on B cell lymphomas and reviews the antibodies to CD3, CD22, CD33, CD52, HLA-DR β chain and HLA-D currently in or proposed for clinical trials, including radiolabelled antibodies. In the last section, Dr. Coller reviews the therapeutic results achieved with abciximab (ReoPro), an antagonist of platelet receptor GPIIbIIIa for the prevention of restenosis in percutaneous coronary interventions and the treatment of unstable angina. The mechanism of action, pharmacology and safety and efficacy of abciximab are reviewed.