Outpatient radioimmunotherapy with Bexxar. Closed, clean air reservoir minimizes personnel radiation exposure

Current status of cancer therapy with radiolabeled monoclonal antibody

Molecular targeting therapy has become a relevant therapeutic strategy for cancer. There are several monoclonal antibodies used for the treatment of malignant tumors. Radioimmunoconjugate is composed of antibody and radionuclide showing a synergistic effect of radiation and immunemediated cellular toxicity and thereby enabling increased efficacy and minimizing toxicity. Radioimmunotherapy using 131I- and 90Y-labeled anti-CD20 monoclonal antibodies is now indicated for the treatment of patients with CD20 antigen-expressing relapsed or refractory, low-grade or transformed non-Hodgkin's lymphoma (NHL), including patients who are refractory to anti-CD20 monoclonal antibody (rituximab) therapy in the United States. It has been exhibiting favorable anti-tumor efficacy in patients with NHL as compared with rituximab. Myelosuppression is the main side effect associated with the radioimmunotherapy but is usually reversible, and nonhematologic adverse reactions are mild to moderate. Following the impressive results of therapy using radiolabeled monoclonal antibodies for NHL, radioimmunotherapy for solid tumors has been examined; however, the results were unfavorable and did warrant further clinical trials as a single agent. Future studies on radioimmunotherapy for solid tumors should focus on the new strategies of targeting such as locoregional administration for intraperitoneal dissemination, and combination therapy with chemotherapy or cytostatic therapy. Although radioimmunotherapy for NHL has shown excellent results comparable to aggressive chemotherapy without severe adverse effects, additional clinical trials should be performed to define the proper role of radioimmunoconjugates as a relevant strategy for cure of NHL.

Iodine-131 tositumomab (Bexxar): radioimmunoconjugate therapy for indolent and transformed B-cell non-Hodgkin's lymphoma

Tositumomab is an immunoglobulin G murine monoclonal antibody that binds to the CD20 antigen on the surface of normal and malignant human B-cells. Tositumomab is linked covalently with iodine-131 to produce the radioimmunoconjugate iodine-131 tositumomab (Bexxar). The iodine-131 tositumomab regimen was approved by the US Food and Drug Administration in June 2003 for the treatment of patients with CD20-positive, follicular non-Hodgkin's lymphoma, both with and without transformation, whose disease is refractory to rituximab (Rituxan) and has relapsed following chemotherapy. The dose-limiting toxicity of iodine-131 tositumomab is bone marrow suppression and resulting cytopenias. Unlike chemotherapy, the majority of nonhematologic adverse events associated with iodine-131 tositumomab are mild to moderate in nature and usually self limited. Iodine-131 tositumomab represents one of the most active single agents for the treatment of recurrent indolent and transformed B-cell non-Hodgkin's lymphoma, as demonstrated by several clinical trials summarized in this review. At the present time, the use of radioimmunoconjugate therapy is largely limited to patients with disease refractory to rituximab therapy and transformed disease not amenable to high-dose therapy and autologous stem cell support. Longer follow-up of ongoing clinical trials should provide reassurance as to safety and insights as to the additive stem cell toxicity from iodine-131 tositumomab administration. Studies are also addressing the role of iodine-131 tositumomab as a component of initial therapy for indolent non-Hodgkin's lymphoma and in additional histologies of non-Hodgkin's lymphoma.

Biotechnology and drug discovery: from bench to bedside

New biotechnology and drug discovery technologies are facilitating the rapid expansion of the clinical drug chest, empowering clinicians with a better understanding of disease as well as novel modalities for treating patients. Important research tools and themes include genomics, proteomics, ligand-receptor interaction, signal transduction, rational drug design, biochips, and microarrays. Emerging drug classes include monoclonal antibodies, cancer vaccines, gene therapy, antisense strands, enzymes, and proteins. In this article, we review these topics and illustrate their potential impact by presenting an overview of promising drugs in the pipeline. Clinicians who use these novel treatments must become familiar with these trends.

Ibritumomab; Tositumomab

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column focuses on the commercially available and investigational agents used to treat malignant diseases and reviews issues related to the preparation, dispensing, and administration of cancer chemotherapy.

Radiation safety with Yttrium 90 ibritumomab tiuxetan (Zevalin) radioimmunotherapy

OBJECTIVES

To present pertinent issues involved in radiation safety in radioimmunotherapy with 90Y ibritumomab tiuxetan.

DATA SOURCES

Published clinical trials of 90Y ibritumomab tiuxetan and secondary literature on radiation safety and radioimmunotherapy.

CONCLUSION

Radioimmunotherapy with 90Y ibritumomab tiuxetan is safe and effective in the indicated population, and radiation safety requirements for caregivers and patients are minimal. Yttrium 90 ibritumomab is routinely and safety administered as an outpatient procedure; safety precautions are universal precautions, with the addition of acrylic shielding for the preparation and administration of the radiolabeled dose.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses play a key role in the multidisciplinary team. By observing universal precautions, and advising patients to do the same, oncology nurses may facilitate the safe and effective administration of the ibritumomab tiuxetan regimen.

Antibody therapy of non-Hodgkin's B-cell lymphoma

Engineering antibodies with reduced immunogenicity and enhanced effector functions, and selecting antigen targets with the appropriate specificity, density, and/or functionality, have contributed to the recent clinical successes in using unconjugated "naked" antibody therapies of B-cell lymphoma (rituximab) and breast carcinoma (Herceptin). The non-overlapping toxicities of naked antibodies and chemotherapy, together with their potential synergy, which is based on unique and complementary mechanisms of action, have contributed to the creation of new standards of care in cancer therapy and management. Clinical trial results supporting these concepts are presented. Furthermore, the exquisite specificity of antibodies renders them ideal vehicles for selective delivery of toxic payloads such as drugs or radionuclides. Although successful in therapy of hematological cancers (Zevalin, Mylotarg), the broader application of these technologies to carcinomas still remains to be proven in clinical testing. Engineering of antibody constructs with optimal blood clearance and tumor-targeting kinetics, and selecting the radionuclide that may deliver sufficient radiation energy to kill the more radio-resistant carcinomas, are discussed. With the advent of genomics and proteomics, new membrane-associated tumor antigens are being discovered and will provide novel targets for future antibody therapy of cancer.