Rituximab: expanding role in therapy for lymphomas and autoimmune diseases

Long-term remission from life-threatening hypercoagulable state associated with lupus anticoagulant (LA) following rituximab therapy

Rituximab, a chimeric monoclonal CD20 antibody, is useful in the treatment of B-cell lymphomas and certain autoimmune diseases. We report a successful outcome of rituximab for life threatening hypercoagulable state associated with lupus anticoagulant (LA). A 30-year-old woman initially presented 10 years ago with DVT and positive serology for SLE and LA. While on Coumadin, she suffered from recurrent DVT in the legs and arms, pulmonary emboli, Budd-Chiari syndrome, mesenteric vein thrombosis, bone infarcts, recurrent strokes, and chronic ITP. All measures including plasmapheresis and monthly IV cyclophosphamide were of no benefit. She was recently admitted with spontaneous subdural hematoma with INR of 3.8. Upon discontinuation of anticoagulation for surgical drainage, she developed acute abdomen from thrombosis and recurrent DVT. Because she had failed prior standard measures, 4 weekly infusions of rituximab (375 mg/m2) were given following 2 rounds of plasmapheresis. Subsequently, she made a remarkable recovery over the next month and has been free of thrombosis on Coumadin for over 15 months. LA, IgM antibodies to cardiolipin, and B2GP1 were consistently positive. After rituximab therapy, LA became negative and IgM antibodies to cardiolipin decreased and ITP went into remission. Rituximab induced a lasting remission in a woman suffering from life-threatening hypercoagulable state associated with LA. Her clinical remission was associated with disappearance of LA.

Rituximab induced remission in a patient with Wegener's granulomatosis

BACKGROUND

Wegener's granulomatosis is a form of systemic vasculitis typically involving the kidneys and upper and lower respiratory tract. Treatment employing cyclophosphamide and prednisone has improved prognosis, but relapses and treatment-induced side effects still cause severe morbidity and frequent mortality. There is therefore an urgent need to find new treatment modalities that are efficient and cause few side effects. Chimeric anti-CD20 (rituximab) may be one such treatment, apparently working in part by suppressing anti-PR3 production.

PATIENTS AND METHODS

We describe a 26-year-old man with two relapses while on azathioprine and mycophenolate necessitating a high cumulative dose of cyclophosphamide. He was treated with a single standard course of rituximab while continuing steroids and mycophenolate.

RESULTS

After 4 months, rituximab led to resolution of pulmonary lesions and also rapidly caused normalization of elevated anti-PR3. He still remains in complete remission 11 months later with a negative anti-PR3 and normal kidney function. There were no side effects to rituximab.

CONCLUSION

Rituximab may be effective and seems to be safe in inducing remission in Wegener's granulomatosis. Studies are needed to establish the long-term benefit of this expensive treatment.

Minimizing the Immunogenicity of Antibodies for Clinical Application

The clinical utility of murine monoclonal antibodies has been greatly limited by the human anti-murine antibody responses they effect in patients. To make them less immunogenic, murine antibodies have been genetically engineered to progressively replace their murine content with that of their human counterparts. This review describes the genetic approaches that have been used to humanize murine antibodies, including the generation of mouse-human chimeric antibodies, veneering of the mouse variable regions, and the grafting of murine complementarity-determining regions (CDRs) onto the variable light (VL) and variable heavy (VH) frameworks of human immunoglobulin molecules, while retaining only those murine framework residues deemed essential for the integrity of the antigen-binding site. To minimize the anti-idiotypic responses that could still be evoked by the murine CDRs in humanized antibodies, two approaches have also been described. These are based on grafting onto the human frameworks the 'abbreviated' CDRs or only the specificity-determining residues (SDRs), the CDR residues that are involved in antigen interaction. The SDRs are identified through the help of the database of three-dimensional structures of antibody:antigen complexes or by mutational analysis of the antibody-combining site. In addition, we also describe the use of in vitro affinity maturation to enhance the binding affinity of humanized antibodies, as well as the manipulation of framework residues to maximize their human content and minimize their immunogenic potential.

Anticalins in Drug Development

Anticalins are a novel class of engineered ligand-binding proteins that are prepared from lipocalins--conventional plasma proteins in humans--via targeted random mutagenesis and selection against prescribed haptens or antigens. The first anticalins were selected to bind to small ligands, such as the cardioactive drug digoxin. Recently, libraries that also permit the generation of anticalins with high affinities and specificities for protein targets, especially disease-related cell-surface receptors, have been constructed. Anticalins are much smaller than antibodies or their antigen-binding fragments, lack glycosylation as well as immunological effector functions, and consist of a single, stably folded polypeptide chain. Thus, they offer benefits as biopharmaceuticals in several areas of medical therapy, for example as receptor antagonists or as effective antidotes against toxic compounds.

Cell therapy for autoimmune diseases: does it have a future?

Almost all current therapeutic concepts in autoimmune diseases are based on the systemic suppression of immune functions and are not curative. The recent introduction of biologicals such as tumour necrosis factor blocking antibodies or receptors has added greater specificity to efficient management of disease by targeted suppression of rheumatic inflammation. It is evident, however, that only the elimination of the cells secreting inflammatory mediators, rather than the blockade of secreted molecules, will offer real specific therapeutic advantages in the future. Merely the elimination of such cells and also cells controlling the secreting effector cells could be curative and induce true long term remissions. We review here the state of the art and future therapeutic concepts that are based on the specific modulation of pathogenic cells that induce and sustain autoimmune inflammation. This sounds visionary, however, a variety of basic tools are at hand now. Thus, direct and specific cell therapy of rheumatic diseases will become a true alternative to conventional therapies.

Combination immunotherapy with a CpG oligonucleotide (1018 ISS) and rituximab in patients with non-Hodgkin lymphoma: increased interferon-alpha/beta-inducible gene expression, without significant toxicity

CpG oligodeoxynucleotides (CpG-ODNs) affect innate and adaptive immune responses, including antigen presentation, costimulatory molecule expression, dendritic cell maturation, and induction of cytokines enhancing antibody-dependent cell-mediated cytotoxicity (ADCC). We conducted a phase 1 study evaluating 4 dose levels of a CpG-ODN (1018 ISS) with rituximab in 20 patients with relapsed non-Hodgkin lymphoma (NHL). Patients received CpG once a week for 4 weeks beginning after the second of 4 rituximab infusions. Adverse events were minimal. Quantitative polymerase chain reaction (PCR) measurements of a panel of genes inducible by CpG-ODN and interferons were performed on blood samples collected before and 24 hours after CpG. A dose-related increase was measured in the expression of several interferon-inducible genes after CpG and correlated with serum levels of 2'-5' oligoadenylate synthetase (OAS), a validated interferon response marker. Genes induced selectively by interferon-gamma (IFN-gamma) were not significantly induced by CpG. In conclusion, we have defined a set of gene expression markers that provide a sensitive measure of biologic responses of patients to CpG therapy in a dose-related manner. Moreover, all the genes significantly induced by this CpG are regulated by type 1 interferons, providing insight into the dominant immune mechanisms in humans. CpG treatment resulted in no significant toxicity, providing rationale for further testing of this exciting combination immunotherapy approach to NHL.