Idiotype vaccine strategies for treatment of follicular lymphoma

Follicular lymphoma is an indolent lymphoma associated with a relapsing course. Immunization with tumor B cell idiotype (Id; a unique variable region of surface B cell immunoglobulin) may induce humoral and cellular immune response against the tumor. Based on promising results from early phase clinical trials with Id vaccine, three Phase III trials were initiated, which, despite failing to meet their primary end points, still provided a glimmer of optimism. This article describes the clinical development of the Id vaccine against follicular lymphoma, outlines the outcomes of clinical trials and delineates the future prospects for the integration of the idiotype vaccine into follicular lymphoma treatment.

A phase 2 trial of immunotherapy with mitumprotimut-T (Id-KLH) and GM-CSF following rituximab in follicular B-cell lymphoma

We evaluated the efficacy and safety of patient-specific immunotherapy with mitumprotimut-T idiotype keyhole limpet hemocyanin and granulocyte-monocyte colony-stimulating factor (GM-CSF) following rituximab in patients with follicular B-cell lymphoma. Patients with previously untreated or relapsed/refractory CD20+ follicular lymphoma received 4 weekly infusions of rituximab and those with a complete response (CR), partial response (PR), or stable disease received mitumprotimut-T and GM-CSF injections subcutaneously. Courses were given monthly for 6 doses, every 2 months for 6 doses, and then every 3 months until disease progression. Computed tomography scans were obtained every 3 to 6 months and reviewed centrally. The primary endpoint was event-free survival (EFS). Among 103 patients treated with rituximab, 92 (54 relapsed/refractory and 38 previously untreated) received mitumprotimut-T/GM-CSF; median age was 53 years, 91% had stage III to IV disease, and 59% had failed earlier therapy. The premitumprotimut-T objective response rate was 47% (2 CRs, 41 PRs). During the mitumprotimut-T treatment phase, 16 patients converted to CR resulting in an overall objective response rate of 60% (18 CRs, 37 PRs). Median EFS was 15.2, 20.8, and 13.5 months for all, treatment-naive, and relapsed/refractory disease patients, respectively. Anti-Id cellular immune responses were detected in 13 of 18 (72%) patients and humoral immune responses in 17 of 83 (20%) patients. Adverse events were usually mild-to-moderate. The most common adverse event was injection site reactions. Mitumprotimut-T/GM-CSF-induced anti-Id cellular immune responses in most patients. The occurrence of late CRs and favorable EFS suggested a clinical benefit of active immunotherapy and led to a placebo-controlled phase 3 trial.

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.

BiovaxID idiotype vaccination: active immunotherapy for follicular lymphoma

Although advanced-stage follicular lymphoma (FL) has been considered incurable with standard therapy, novel strategies that utilize immunotherapy provide opportunities for prolonging disease-free survival. While passive immunotherapy with antibodies targeting the CD20 antigen on B cells has been the most widely applied lymphoma immunotherapy, active immunization with vaccines derived from the immunoglobulin idiotype present on the surface of FL provides an opportunity to induce specific humoral and cellular immune responses to the tumor, and have been demonstrated to produce significant benefits in prolonging disease-free survival. Promoting the benefits of all forms of immunotherapy will likely depend upon improving complete remission rates with initial treatment. BiovaxID, a patient-specific idiotype vaccine, has demonstrated durable remissions when administered to FL patients in first complete remission along with keyhole limpet hemocyanin and granulocyte-macrophage colony-stimulating factor, and is now undergoing evaluation in a pivotal Phase III clinical trial.