Idiotype vaccines produced with a non-cytopathic alphavirus self-amplifying RNA vector induce antitumor responses in a murine model of B-cell lymphoma.

A promising therapy for patients with B-cell lymphoma is based on vaccination with idiotype monoclonal antibodies (mAbs). Since idiotypes are different in each tumor, a personalized vaccine has to be produced for each patient. Expression of immunoglobulins with appropriate post-translational modifications for human use often requires the use of stable mammalian cells that can be scaled-up to reach the desired level of production. We have used a noncytopathic self-amplifying RNA vector derived from Semliki Forest virus (ncSFV) to generate BHK cell lines expressing murine follicular lymphoma-derived idiotype A20 mAb. ncSFV/BHK cell lines expressed approximately 2 mg/L/24 h of A20 mAb with proper quaternary structure and a glycosylation pattern similar to that of A20 mAb produced by hybridoma cells. A20 mAb purified from the supernatant of a ncSFV cell line, or from the hybridoma, was conjugated to keyhole limpet hemocyanin and used to immunize Balb/c mice by administration of four weekly doses of 25 µg of mAb. Both idiotype mAbs were able to induce a similar antitumor protection and longer survival compared to non-immunized mice. These results indicate that the ncSFV RNA vector could represent a quick and efficient system to produce patient-specific idiotypes with potential application as lymphoma vaccines.

CD138 plasma cells may predict brain metastasis recurrence following resection and stereotactic radiosurgery.

We sought to identify candidate biomarkers for early brain metastasis (BM) recurrence in patients who underwent craniotomy followed by adjuvant stereotactic radiosurgery. RNA sequencing was performed on eight resected brain metastasis tissue samples and revealed B-cell related genes to be highly expressed in patients who did not experience a distant brain failure and had prolonged overall survival. To translate the findings from RNA sequencing data, we performed immunohistochemistry to stain for B and T cell markers from formalin-fixed parffin-embedded tissue blocks on 13 patients. CD138 expressing plasma cells were identified and quantitatively assessed for each tumor sample. Patients' tumor tissues that expressed high levels of CD138 plasma cells (N = 4) had a statistically significant improvement in OS compared to low levels of CD138 (N = 9) (p = 0.01). Although these findings are preliminary, the significance of CD138 expressing plasma cells within BM specimens should be investigated in a larger cohort. Immunologic markers based on resection cavity analysis could be predictive for determining patient outcomes following cavity-directed SRS.

Identification of LAG3 high affinity aptamers by HT-SELEX and Conserved Motif Accumulation (CMA).

LAG3 receptor belongs to a family of immune-checkpoints expressed in T lymphocytes and other cells of the immune system. It plays an important role as a rheostat of the immune response. Focus on this receptor as a potential therapeutic target in cancer immunotherapy has been underscored after the success of other immune-checkpoint blockade strategies in clinical trials. LAG3 showcases the interest in the field of autoimmunity as several studies show that LAG3-targeting antibodies can also be used for the treatment of autoimmune diseases. In this work we describe the identification of a high-affinity LAG3 aptamer by High Throughput Sequencing SELEX in combination with a study of potential conserved binding modes according to sequence conservation by using 2D-structure prediction and 3D-RNA modeling using Rosetta. The aptamer with the highest accumulation of these conserved sequence motifs displays the highest affinity to LAG3 recombinant soluble proteins and binds to LAG3-expressing lymphocytes. The aptamer described herein has the potential to be used as a therapeutic agent, as it enhances the threshold of T-cell activation. Nonetheless, in future applications, it could also be engineered for treatment of autoimmune diseases by target depletion of LAG3-effector T lymphocytes.

A phase II trial of autologous dendritic cell vaccination and radiochemotherapy following fluorescence-guided surgery in newly diagnosed glioblastoma patients.

BACKGROUND: Prognosis of patients with glioblastoma multiforme (GBM) remains dismal, with median overall survival (OS) of about 15 months. It is therefore crucial to search alternative strategies that improve these results obtained with conventional treatments. In this context, immunotherapy seems to be a promising therapeutic option. We hypothesized that the addition of tumor lysate-pulsed autologous dendritic cells (DCs) vaccination to maximal safe resection followed by radiotherapy and concomitant and adjuvant temozolomide could improve patients' survival. METHODS: We conducted a phase-II clinical trial of autologous DCs vaccination in patients with newly diagnosed patients GBM who were candidates to complete or near complete resection. Candidates were finally included if residual tumor volume was lower than 1 cc on postoperative radiological examination. Autologous DCs were generated from peripheral blood monocytes and pulsed with autologous whole tumor lysate. The vaccination calendar started before radiotherapy and was continued during adjuvant chemotherapy. Progression free survival (PFS) and OS were analyzed with the Kaplan-Meier method. Immune response were assessed in blood samples obtained before each vaccines. RESULTS: Thirty-two consecutive patients were screened, one of which was a screening failure due to insufficient resection. Median age was 61 years (range 42-70). Karnofsky performance score (KPS) was 90-100 in 29%, 80 in 35.5% and 60-70 in 35.5% of cases. MGMT (O6-methylguanine-DNA-methyltransferase) promoter was methylated in 45.2% of patients. No severe adverse effects related to immunotherapy were registered. Median PFS was 12.7 months (CI 95% 7-16) and median OS was 23.4 months (95% CI 16-33.1). Increase in post-vaccination tumor specific immune response after vaccines (proliferation or cytokine production) was detected in 11/27 evaluated patients. No correlation between immune response and survival was found. CONCLUSIONS: Our results suggest that the addition of tumor lysate-pulsed autologous DCs vaccination to tumor resection and combined radio-chemotherapy is feasible and safe. A multicenter randomized clinical trial is warranted to evaluate the potential survival benefit of this therapeutic approach. Trial registration This phase-II trial was registered as EudraCT: 2009-009879-35 and ClinicalTrials.gov Identifier: NCT01006044 retrospectively registered.

Targeting inhibition of Foxp3 by a CD28 2'-Fluro oligonucleotide aptamer conjugated to P60-peptide enhances active cancer immunotherapy.

The specific inhibition of Treg function has long been a major technical challenge in cancer immunotherapy. So far no single cell-surface marker has been identified that could be used to distinguish Treg cells from other lymphocytes. The only available specific marker mostly expressed in Treg is Foxp3, which is an intracellular transcription factor. A targeting molecule able to penetrate the membrane and inhibit Foxp3 within the cell is needed. P60-peptide is able to do that, but due to lack of target specificity, the doses are extremely high. In this study we have shown as a proof of concept that P60 Foxp3 inhibitor peptide can be conjugated with a CD28 targeting aptamer to deliver the peptide to CD28-expressing cells. The AptCD28-P60 construct is a clinically feasible reagent that improves the efficacy of the unconjugated P60 peptide very significantly. This approach was used to inhibit Treg function in a vaccination context, and it has shown a significant improvement in the induced immune response, entailing a lower tumor load in an antigen-specific cancer vaccine protocol.

MRP1-CD28 bi-specific oligonucleotide aptamers: target costimulation to drug-resistant melanoma cancer stem cells.

In this work we show a clinically feasible strategy to convert in situ the own tumor into an endogenous vaccine by coating the melanoma cancerous cells with CD28 costimulatory ligands. This therapeutic approach is aimed at targeting T-cell costimulation to chemotherapy-resistant tumors which are refractory and been considered as untreatable cancers. These tumors are usually defined by an enrichment of cancer stem cells and characterized by the higher expression of chemotherapy-resistant proteins. In this work we develop the first aptamer that targets chemotherapy-resistant tumors expressing MRP1 through a novel combinatorial peptide-cell SELEX. With the use of the MRP1 aptamer we engineer a MRP1-CD28 bivalent aptamer that is able to bind MRP1-expressing tumors and deliver the CD28 costimulatory signal to tumor-infiltrating lymphocytes. The bi-specific aptamer is able to enhance costimulation in chemotherapy-resistant tumors. Melanoma-bearing mice systemically treated with MRP1-CD28 bivalent aptamer show reduced growth, thus proving an improved mice survival.Besides, we have designed a technically feasible and translational whole-cell vaccine (Aptvax). Disaggregated cells from tumors can be directly decorated with costimulatory ligand aptamers to generate the vaccine Aptvax. CD28Aptvax made of irradiated tumor cells coated with the CD28-agonistic aptamer attached to MRP1 elicits a strong tumor- cell immune response against melanoma tumors reducing tumor growth.

Identification of TIM3 2'-fluoro oligonucleotide aptamer by HT-SELEX for cancer immunotherapy.

TIM3 belongs to a family of receptors that are involved in T-cell exhaustion and Treg functions. The development of new therapeutic agents to block this type of receptors is opening a new avenue in cancer immunotherapy. There are currently several clinical trials ongoing to combine different immune-checkpoint blockades to improve the outcome of cancer patients. Among these combinations we should underline PD1:PDL1 axis and TIM3 blockade, which have shown very promising results in preclinical settings. Most of these types of therapeutic agents are protein cell-derived products, which, although broadly used in clinical settings, are still subject to important limitations. In this work we identify by HT-SELEX TIM3 non-antigenic oligonucleotide aptamers (TIM3Apt) that bind with high affinity and specificity to the extracellular motives of TIM3 on the cell surface. The TIM3Apt1 in its monomeric form displays a potent antagonist capacity on TIM3-expressing lymphocytes, determining the increase of IFN-γ secretion. In colon carcinoma tumor-bearing mice, the combinatorial treatment of TIM3Apt1 and PDL1-antibody blockade is synergistic with a remarkable antitumor effect. Immunotherapeutic aptamers could represent an attractive alternative to monoclonal antibodies, as they exhibit important advantages; namely, lower antigenicity, being chemically synthesized agents with a lower price of manufacture, providing higher malleability, and antidote availability.

Clinical Safety and Immunogenicity of Tumor-Targeted, Plant-Made Id-KLH Conjugate Vaccines for Follicular Lymphoma.

We report the first evaluation of plant-made conjugate vaccines for targeted treatment of B-cell follicular lymphoma (FL) in a Phase I safety and immunogenicity clinical study. Each recombinant personalized immunogen consisted of a tumor-derived, plant-produced idiotypic antibody (Ab) hybrid comprising the hypervariable regions of the tumor-associated light and heavy Ab chains, genetically grafted onto a common human IgG1 scaffold. Each immunogen was produced in Nicotiana benthamiana plants using twin magnICON vectors expressing the light and heavy chains of the idiotypic Ab. Each purified Ab was chemically linked to the carrier protein keyhole limpet hemocyanin (KLH) to form a conjugate vaccine. The vaccines were administered to FL patients over a series of ≥6 subcutaneous injections in conjunction with the adjuvant Leukine (GM-CSF). The 27 patients enrolled in the study had previously received non-anti-CD20 cytoreductive therapy followed by ≥4 months of immune recovery prior to first vaccination. Of 11 patients who became evaluable at study conclusion, 82% (9/11) displayed a vaccine-induced, idiotype-specific cellular and/or humoral immune response. No patients showed serious adverse events (SAE) related to vaccination. The fully scalable plant-based manufacturing process yields safe and immunogenic personalized FL vaccines that can be produced within weeks of obtaining patient biopsies.

2-fluoro-RNA oligonucleotide CD40 targeted aptamers for the control of B lymphoma and bone-marrow aplasia.

Recent studies have underscored the importance of immunomodulatory antibodies in the treatment of solid and hematological tumors. ODN-Aptamers are rising as a novel class of drugs that can rival therapeutic antibodies. The success of some of the current cancer immunotherapy approaches in oncological patients depends on the intrinsic antigenicity of each tumor as has recently been disclosed, and it is hampered in those patients that are treated with myeloablative chemotherapy or radiotherapy, which induce profound immunosuppression. CD40 agonist and antagonist molecules offer a new therapeutic alternative which has the potential to generate anticancer effects by different mechanisms. HS-SELEX was performed to identify high-affinity aptamers against CD40, and three therapeutic CD40 constructs were engineered as: CD40 agonist aptamer, CD40 antagonist aptamer and CD40 agonistic aptamer-shRNA chimera. It is shown that CD40 agonist aptamers can be used to promote bone-marrow aplasia recovery. CD40 antagonist aptamers are revealed to have a direct antitumor effect on CD40-expressing B-cell lymphoma in vitro and in vivo. Further, in order to identify a therapeutic reagent that will generate the optimal conditions for cancer immunotherapy (antigen-presenting cell activation, tumor antigenicity enhancement and bone-marrow aplasia recovery), CD40 agonist aptamer-shRNA chimera was generated to target the inhibition of the Nonsense mRNA Mediated Decay (NMD) to tumor cells.

Idiotype vaccine production using hybridoma technology.

Non-Hodgkin's lymphoma (NHL) is the most common hematological malignancy both in Europe and in the United States. Follicular lymphoma (FL), a tumor comprised of mature B cells, represents one fourth of all NHL and, despite good response rates to standard treatments, tends to frequently relapse to such an extent that it is still considered incurable. Among several alternative therapeutic options actively being pursued, immunotherapy by idiotypic vaccination is in the forefront of clinical experimental medicine. The idiotype vaccine consists of the tumor-specific immunoglobulin conjugated with keyhole limpet hemocyanin (KLH) and administered together with an adjuvant. Over the last 20 years, researchers have proven that this vaccine can induce specific immune responses. Too, those patients with such responses experience a disease-free survival longer than normally achievable, although these latter results require further confirmation in large clinical trials. Traditionally, idiotype vaccines have been produced through hybridoma technology. In this chapter this technology is described.

CD28 aptamers as powerful immune response modulators.

CD28 is one of the main costimulatory receptors responsible for the proper activation of T lymphocytes. We have isolated two aptamers that bind to the CD28 receptor. As a monomer, one of them interfered with the binding of CD28 to its ligand (B7), precluding the costimulatory signal, whereas the other one was inactive. However, dimerization of any of the anti-CD28 aptamers was sufficient to provide an artificial costimulatory signal. No antibody has featured a dual function (i.e., the ability to work as agonist and antagonist) to date. Two different agonistic structures were engineered for each anti-CD28 aptamer. One showed remarkably improved costimulatory properties, surpassing the agonistic effect of an anti-CD28 antibody. Moreover, we showed in vivo that the CD28 agonistic aptamer is capable of enhancing the cellular immune response against a lymphoma idiotype and of prolonging survival of mice which receive the aptamer together with an idiotype vaccine. The CD28 aptamers described in this work could be used to modulate the immune response either blocking the interaction with B7 or enhancing vaccine-induced immune responses in cancer immunotherapy.Molecular Therapy - Nucleic Acids (2013) 2, e98; doi:10.1038/mtna.2013.26; published online 11 June 2013.

Dendritic cell vaccination in glioblastoma after fluorescence-guided resection.

AIM: To assess whether the addition of a customized, active immunotherapy to standard of care including fluorescence-guided surgery, may provide hints of an improved survival for patients with poor-prognosis, incurable glioblastoma multiform. METHODS: Preliminary to our ongoing, phase-II clinical trial, we conducted a small pilot study enrolling five consecutive patients with resectable glioblastoma. In terms of Recursive Partitioning Analysis, four patients were class V and one was class IV. In all five cases, fluorescence-guided surgery was employed, followed by rapid steroid discontinuation. Patients were then treated with a combination of standard radio-chemotherapy with temozolomide and tumor lysate-pulsed, mature dendritic cell-based vaccinations. RESULTS: Though all five patients ultimately progressed, with any further treatment left to the sole decision of the treating oncologist, active immunotherapy was very well tolerated and induced specific immune responses in all three patients for whom enough material was available for such an assessment. Median progression-free survival was 16.1 mo. Even more important, median and mean overall survival were 27 mo and 26 mo, respectively. Three patients have died with an overall survival of 9 mo, 27 mo and 27.4 mo, while the other two are still alive at 32 mo and 36 mo, the former receiving treatment with bevacizumab, while the latter has now been off therapy for 12 mo. Four of five patients were alive at two years. CONCLUSION: Active immunotherapy with tumor lysate-pulsed, autologous dendritic cells is feasible, safe, well tolerated and biologically efficacious. A phase-II study is ongoing to possibly improve further on our very encouraging clinical results.

BiovaxID®: a customized idiotype vaccine for the treatment of B-cell lymphoma.

Most patients with B-cell lymphoma face an often incurable disease, particularly those diagnosed with an indolent subtype. The addition of passive immunotherapy to old and new chemotherapy regimens has improved both response rates and disease-free survival, leading in many cases to an extended overall survival. However, a cure remains elusive in most cases. For this reason, the patient- and tumor-specific idiotype, that is the collection of epitopes exclusively presented by the tumor clone's surface immunoglobulin, has been extensively studied as a privileged target for vaccine therapy, aiming at preventing disease re-occurrence after standard treatment. BiovaxID(®) (Biovest International, FL, USA), the most clinically advanced among such therapeutic vaccines, finds itself at a crucial turning point when it comes to further development. Both clinical trials in which it has been formally employed have shown intriguing results. Independent studies using slightly different versions of a conceptually identical vaccine provided all proofs of principle required to ascertain the vaccine's value - biological and clinical efficacy as well as clinical benefit. However, all these data have failed to bring an idiotype vaccine to the market owing to reasons that often have very little to do with the product itself. In fact, some successful studies were not conceived with this goal in mind, while others simply did not enroll enough patients to convincingly make their case for regulatory approval. It is likely that one or more new clinical trials will have to be successfully completed to reach the ultimate goal - that is, to make BiovaxID available to most patients and to adequately position it in the very crowded therapeutic algorithm of B-cell lymphoma.

Idiotype vaccines for lymphoma: Potential factors predicting the induction of immune responses.

Over the last two decades, lymphoma idiotype vaccines have been the first human cancer vaccines to show striking evidence of biological and clinical efficacy on the one hand, as well as clinical benefit on the other. More recently, however, three large-scale, independent, randomized clinical trials on idiotypic vaccination have failed to achieve their main clinical endpoints for reasons likely to depend more on flaws in each clinical trial's study design than on each vaccination strategy per se. Independently of these considerations, a major hurdle for the development of this substantially innocuous and yet potentially very effective type of treatment has been the fact that, even to date, no factors ascertainable before vaccination have been prospectively singled out as predictors of subsequently vaccine-induced, idiotype-specific immune as well as clinical responses. The aim of this review article is precisely to analyze what has been and what could be done in this respect in order to give a greater chance of success to future trials aimed at regulatory approval of idiotype vaccines.

Idiotype vaccines for lymphoma therapy.

Despite having been the first cancer vaccine to provide clear-cut evidence of biological and clinical efficacy as well as of clinical benefit in humans, idiotype vaccines have failed to become the first therapeutic cancer vaccine to be granted regulatory approval. Indeed, idiotypic vaccination is still an experimental therapeutic option for some types of B-cell malignancy over 20 years after its first use in patients with lymphoma. The ultimate reason for this situation lies in the recent failure of three large-scale, independent, randomized trials to achieve their respective main clinical end points. Interestingly, each trial had been designed with intrinsic pitfalls that are likely to have influenced, and perhaps even entirely compromized, all chances each study had to succeed. Therefore, it is difficult to conclude whether any of the different idiotype vaccines employed so far may still represent an ideal candidate for further trials. Meanwhile, other idiotype vaccine formulations are under active investigation.

Stem cell transplant and idiotypic vaccination for B-cell malignancies.

Several types of B-cell malignancy, including but not limited to multiple myeloma and follicular lymphoma, are still considered incurable. In a substantial number of cases, patients must undergo either autologous or allogeneic stem cell transplantation as a standard of care procedure for their disease. Among experimental treatments for multiple myeloma and follicular lymphoma, idiotypic vaccination has been attempted over the last two decades with variable degrees of success. Few clinical trials have combined stem cell transplant procedures with idiotypic vaccination, and they are the subject of this review, which will also include some of our original data, as well as our overall evaluation of this field of clinical investigation. Although apparently at the opposite extremes of the therapeutic option array, toxicity-burdened stem cell transplantation and virtually innocuous idiotypic vaccination might well offer a sound curative opportunity to some patients with otherwise incurable B-cell malignancies, provided that the latter treatment first succeeds at obtaining regulatory approval.

Hybridoma-Derived Idiotype Vaccine for Lymphoma: Approval Must Wait.

Hybridoma-derived idiotype vaccines have been used for the experimental treatment of human lymphoma over the last twenty years, providing evidence of biological efficacy, clinical efficacy and clinical benefit. However, the product that has come closer to regulatory approval is unlikely to clear that hurdle due to the insufficiently robust data obtained in a recently closed clinical trial. This review aims at discussing the reasons for hybridoma-derived idiotype vaccines, more difficult to produce but also more successful than recombinant idiotype vaccines so far, are unlikely to gain regulatory approval. In particular, it is necessary to examine the many peculiar features of this therapeutic approach in a broader context, with special attention to concepts like customized active immunotherapy and randomization. Most published trials based on hybridoma-derived idiotype vaccines are being analyzed, together with the yet non-peer reviewed data from the only randomized study conducted so far with this product, and with the main trials on recombinant idiotype vaccines for thorough comparison. All in all, the sole randomized trial ever conducted on hybridoma-derived idiotype vaccines failed to achieve its primary clinical end point because of an insufficient accrual and because the statistical significance achieved was not as stringent as required for regulatory approval.

Idiotype vaccines for lymphoma: proof-of-principles and clinical trial failures.

The clonal immunoglobulin idiotype displayed on the surface of most malignant B cells is a patient- and tumour-specific antigen that can be used for therapeutic vaccination. Several studies have confirmed the biological efficacy of soluble protein idiotypic vaccination and two clinical trials have shown the clinical efficacy of this procedure. One study has demonstrated clinical benefit associated with idiotypic vaccination. However, three randomized clinical trials have recently failed to achieve their main end points for reasons that are probably unrelated to the vaccine. While scepticism towards this type of non-toxic medical intervention is mounting, such patient-specific treatments might yet see the light of day through better designed clinical trials.

Autoimmunity and lymphoma: is mantle cell lymphoma a mistake of the receptor editing mechanism?

Mantle cell lymphoma (MCL) is an aggressive B cell malignancy, which is believed to originate from naïve B cells in the mantle zone of lymph nodes. We speculate that a possible mechanistic hypothesis for the generation of MCL is one in which receptor editing and germinal centre exclusion could be involved in the molecular development and in the display of clinical characteristics of this rare, aggressive and scarcely understood lymphoma. The hypothesis is supported by a preferential autoimmune related IGVH gene utilization in MCL, where VH3-21, VH4-34 and VH5-51 genes are predominant, and by the fact that MCL expresses immunoglobulin light chain (IgL) lambda more frequently than other non-Hodgkin's lymphomas and that IgL lambda-producing B cells usually delete one or both their IgL kappa genes.