Therapeutic idiotype vaccines in B lymphoproliferative diseases

Immune Response Regulation by Antigen Receptors' Clone-Specific Nonself Parts

Antigen determinants (epitopes) are recognized by the combining sites (paratopes) of B and T cell antigen receptors (BCR/TCR), which again express clone-specific epitopes (idiotopes) that can be recognized by BCR/TCR not only of genetically different donors but also within the autologous immune system. While xenogeneic and allogeneic anti-idiotypic BCR/TCR are broadly cross-reactive, only autologous anti-idiotypes are truly specific and of functional regulatory relevance within a particular immune system. Autologous BCR/TCR idiotopes are (a) somatically created at the third complementarity-determining regions, (b) through mutations introduced into BCRs during adaptive immune responses, and (c) through the conformational impact of both. As these idiotypic characters have no genomic counterparts they have to be regarded as antigen receptor-intrinsic nonself-portions. Although foreign, however, they are per se non-immunogenic, but in conjunction with immunogenicity- and adjuvanticity-providing antigen-induced immune responses, they induce abating regulatory idiotypic chain reactions. The dualistic nature of antigen receptors of seeing antigens (self and nonself alike) and being nonself at the same time has far reaching consequences for an understanding of the regulation of adaptive immune responses.

Vaccination with single chain antigen receptors for islet-derived peptides presented on I-A(g7) delays diabetes in NOD mice by inducing anergy in self-reactiveT-cells

To develop a vaccination approach for prevention of type 1 diabetes (T1D) that selectively attenuates self-reactive T-cells targeting specific autoantigens, we selected phage-displayed single chain antigen receptor libraries for clones binding to a complex of the NOD classII MHC I-A(g7) and epitopes derived from the islet autoantigen RegII. Libraries were generated from B-cell receptor repertoires of classII-mismatched mice immunized with RegII-pulsed NOD antigen presenting cells or from T-cell receptor repertoires in pancreatic lymph nodes of NOD mice. Both approaches yielded clones recognizing a RegII-derived epitope in the context of I-A(g7), which activated autoreactive CD4(+) T-cells. A receptor with different specificity was obtained by converting the BDC2.5 TCR into single chain form. B- but not T-cells from donors vaccinated with the clones transferred protection from diabetes to NOD-SCID recipients if the specificity of the diabetes inducer cell and the single chain receptor were matched. B-cells and antibodies from donors vaccinated with the BDC2.5 single chain receptor induced a state of profound anergy in T-cells of BDC2.5 TCR transgenic NOD recipients while B-cells from donors vaccinated with a single chain receptor specific for I-A(g7) RegII peptide complexes induced only partial non-responsiveness. Vaccination of normal NOD mice with receptors recognizing I-A(g7) RegII peptide complexes or with the BDC2.5 single chain receptor delayed onset of T1D. Thus anti-idiotypic vaccination can be successfully applied to T1D with vaccines either generated from self-reactive T-cell clones or derived from antigen receptor libraries.

Plant-produced idiotype vaccines for the treatment of non-Hodgkin's lymphoma: safety and immunogenicity in a phase I clinical study

Plant-made vaccines have been the subject of intense interest because they can be produced economically in large scale without the use of animal-derived components. Plant-made therapeutic vaccines against challenging chronic diseases, such as cancer, have received little research attention, and no previous human clinical trials have been conducted in this vaccine category. We document the feasibility of using a plant viral expression system to produce personalized (patient-specific) recombinant idiotype vaccines against follicular B cell lymphoma and the results of administering these vaccines to lymphoma patients in a phase I safety and immunogenicity clinical trial. The system allowed rapid production and recovery of idiotypic single-chain antibodies (scFv) derived from each patient's tumor and immunization of patients with their own individual therapeutic antigen. Both low and high doses of vaccines, administered alone or co-administered with the adjuvant GM-CSF, were well tolerated with no serious adverse events. A majority (>70%) of the patients developed cellular or humoral immune responses, and 47% of the patients developed antigen-specific responses. Because 15 of 16 vaccines were glycosylated in plants, this study also shows that variation in patterns of antigen glycosylation do not impair the immunogenicity or affect the safety of the vaccines. Collectively, these findings support the conclusion that plant-produced idiotype vaccines are feasible to produce, safe to administer, and a viable option for idiotype-specific immune therapy in follicular lymphoma patients.

Long-term effects of idiotype vaccination on the specific T-cell response in peripheral blood and bone marrow of multiple myeloma patients

OBJECTIVES

To elucidate long-term effects of idiotype (Id) vaccination on Id-specific T cells of multiple myeloma (MM) patients and compare Id-specific T-cell responses of peripheral blood with those of bone marrow (BM).

MATERIALS AND METHODS

Id-specific T-cell responses of peripheral blood mononuclear cells (PBMC) were compared with those of BM mononuclear cells (BMMC) in 10 MM patients vaccinated with the Id protein at a median time of 41 months since the last immunization. The PBMC responses at late follow-up were also compared with those during active immunization. The responses were assessed by a proliferation assay, enzyme-linked immunospot (ELISPOT) (gamma-interferon), cytometric bead array (CBA) for secreted cytokines and quantitative real-time polymerase chain reaction (QRT-PCR) for cytokine gene expression.

RESULTS

At the late testing time, an Id-specific response was detected in PBMC of five patients (ELISPOT, CBA, QRT-PCR) and in BMMC of four patients (CBA, QRT-PCR). A response in both compartments was noted only in three patients. The cytokines gene profile was consistent with a predominance of Th(2) cells [interleukin (IL)-4, IL-5, IL-10]. Comparison of the Id-specific responses of PBMC during active immunization with those at the late follow-up showed that the frequency and magnitude of the responses had decreased significantly by time (proliferation/ELISPOT) (P < 0.02) and shifted at the gene level from a Th(1) to a Th(2) profile (P < 0.05).

CONCLUSION

Id-specific T-cells may decline overtime and shift toward a Th(2) response and may be found at a similar frequency of patients in blood and BM.

Mechanisms of action of immune tolerance induction against factor VIII in patients with congenital haemophilia A and factor VIII inhibitors

In its most severe form, haemophilia A is a life-threatening haemorrhagic bleeding disorder that is caused by mutations in the factor VIII (FVIII) gene. About 25% of patients who receive replacement therapy with intravenous FVIII products develop neutralising antibodies (FVIII inhibitors) that inhibit the function of substituted FVIII. Long-term application of high or low doses of FVIII has evolved as an effective strategy for eradicating antibodies and inducing long-lasting immune tolerance. Despite clinical experience with the therapy, little is known about the immunological mechanisms that cause the down modulation of FVIII-specific immune responses or the induction of long-lasting immune tolerance against FVIII. This review summarises current knowledge of the immunological mechanisms that might be involved in the induction of immune tolerance against FVIII in patients with haemophilia A who have FVIII inhibitors. In addition to data from patients with haemophilia A, data from patients who have had organ transplants or have immune-related disorders, such as autoimmune diseases, are considered as well as data from animal models.

Novel approaches to the immunotherapy of B-cell malignancies: An update

Immunotherapy of cancer includes both active and adoptive, or passive, forms of immunization to target and eradicate malignant B cells in the host. Advances in the understanding of immunology and tumor-cell evasion of the host immune system, coupled with improved technologies to manipulate immune effectors and tumors, have led to a wide array of novel therapies for B-cell malignancies. As a result, investigators have proposed and tested numerous vaccine strategies able to elicit immune responses to tumor antigens. Furthermore, novel approaches to B-cell-targeted antibody therapies hold promise in advancing this line of treatment, and efficient gene transfer technologies have enabled investigators to manipulate immune effector cells to enhance antitumor activity. Significantly, an increasing number of these novel immune-based therapies are being applied to the clinical setting. Whether findings from these clinical trials, in combination with further preclinical studies, will ultimately translate into improved survival of patients with B-cell malignancies remains to be seen.

Clinical benefit associated with idiotypic vaccination in patients with follicular lymphoma

BACKGROUND

Follicular lymphoma is considered incurable, although cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy can induce sequential remissions. A patient's second complete response is typically shorter than that patient's first complete response. Idiotype vaccines can elicit specific immune responses and molecular remissions in patients with follicular lymphoma. However, a clinical benefit has never been formally proven.

METHODS

Thirty-three consecutive follicular lymphoma patients in first relapse received six monthly cycles of CHOP-like chemotherapy. Patients who achieved a second complete response were vaccinated periodically for more than 2 years with autologous lymphoma-derived idiotype protein vaccine. Specific humoral and cellular responses were assessed, and patients were followed for disease recurrence. Statistical tests were two-sided.

RESULTS

Idiotype vaccine could be produced for 25 patients who had a second complete response. In 20 patients (80%), a humoral (13/20) and/or a cellular (18/20) idiotype-specific response was detected. The median duration of the second complete response has not been reached, but it exceeds 33 months (range = 20+ to 51+ months). None of the 20 responders relapsed while undergoing active vaccination. All responders with enough follow-up for the comparison to be made experienced a second complete response that was statistically significantly (P<.0001) longer than both their first complete response (18 of 18 patients) and than the median duration of a CHOP-induced second complete response, i.e., 13 months (20 of 20 patients). The five nonresponders all had a second complete response that was shorter (median = 10 months; range = 8-13 months) than their first complete response (median = 17 months; range = 10-39 months).

CONCLUSIONS

Idiotypic vaccination induced a specific immune response in the majority of patients with follicular lymphoma. Specific immune response was associated with a dramatic and highly statistically significant increase in disease-free survival. This is the first formal demonstration of clinical benefit associated with the use of a human cancer vaccine.

High-dose factor VIII inhibits factor VIII-specific memory B cells in hemophilia A with factor VIII inhibitors

Hemophilia A in its severe form is a life-threatening hemorrhagic disease that is caused by mutations in the factor VIII (FVIII) gene (symbol F8). About 25% of patients who receive replacement therapy develop neutralizing antibodies that inhibit the function of substituted FVIII. Long-term application of high doses of FVIII has evolved as an effective therapy to eradicate the antibodies and to induce long-lasting immune tolerance. Little is known, however, about the immunologic mechanisms that cause the down-modulation of anti-FVIII antibodies by high doses of FVIII. We report that high doses of FVIII inhibit the restimulation of FVIII-specific memory B cells and their differentiation into antibody-secreting plasma cells in vitro and in vivo in a murine model of hemophilia A. The inhibition of memory B-cell responses is irreversible and not mediated by FVIII-specific T cells. Furthermore, it seems to involve the activation of caspases. We conclude that the inhibition of FVIII-specific memory B cells might be an early event in the down-modulation of anti-FVIII antibodies in patients with hemophilia A who receive high doses of FVIII.