Generation of a Dendritic Cell-based Vaccine in Chronic Lymphocytic Leukaemia Using CliniMACS Platform for Large-scale Production

Apoptotic bodies: bioactive treasure left behind by the dying cells with robust diagnostic and therapeutic application potentials

Apoptosis, a form of programmed cell death, is essential for growth and tissue homeostasis. Apoptotic bodies (ApoBDs) are a form of extracellular vesicles (EVs) released by dying cells in the last stage of apoptosis and were previously regarded as debris of dead cells. Recent studies unraveled that ApoBDs are not cell debris but the bioactive treasure left behind by the dying cells with an important role in intercellular communications related to human health and various diseases. Defective clearance of ApoBDs and infected-cells-derived ApoBDs are possible etiology of some diseases. Therefore, it is necessary to explore the function and mechanism of the action of ApoBDs in different physiological and pathological conditions. Recent advances in ApoBDs have elucidated the immunomodulatory, virus removal, vascular protection, tissue regenerative, and disease diagnostic potential of ApoBDs. Moreover, ApoBDs can be used as drug carriers enhancing drug stability, cellular uptake, and targeted therapy efficacy. These reports from the literature indicate that ApoBDs hold promising potential for diagnosis, prognosis, and treatment of various diseases, including cancer, systemic inflammatory diseases, cardiovascular diseases, and tissue regeneration. This review summarizes the recent advances in ApoBDs-related research and discusses the role of ApoBDs in health and diseases as well as the challenges and prospects of ApoBDs-based diagnostic and therapeutic applications.

Immune Dysfunctions and Immune-Based Therapeutic Interventions in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy characterized by a wide range of tumor-induced alterations, which affect both the innate and adaptive arms of the immune response, and accumulate during disease progression. In recent years, the development of targeted therapies, such as the B-cell receptor signaling inhibitors and the Bcl-2 protein inhibitor venetoclax, has dramatically changed the treatment landscape of CLL. Despite their remarkable anti-tumor activity, targeted agents have some limitations, which include the development of drug resistance mechanisms and the inferior efficacy observed in high-risk patients. Therefore, additional treatments are necessary to obtain deeper responses and overcome drug resistance. Allogeneic hematopoietic stem cell transplantation (HSCT), which exploits immune-mediated graft-versus-leukemia effect to eradicate tumor cells, currently represents the only potentially curative therapeutic option for CLL patients. However, due to its potential toxicities, HSCT can be offered only to a restricted number of younger and fit patients. The growing understanding of the complex interplay between tumor cells and the immune system, which is responsible for immune escape mechanisms and tumor progression, has paved the way for the development of novel immune-based strategies. Despite promising preclinical observations, results from pilot clinical studies exploring the safety and efficacy of novel immune-based therapies have been sometimes suboptimal in terms of long-term tumor control. Therefore, further advances to improve their efficacy are needed. In this context, possible approaches include an earlier timing of immunotherapy within the treatment sequencing, as well as the possibility to improve the efficacy of immunotherapeutic agents by administering them in combination with other anti-tumor drugs. In this review, we will provide a comprehensive overview of main immune defects affecting patients with CLL, also describing the complex networks leading to immune evasion and tumor progression. From the therapeutic standpoint, we will go through the evolution of immune-based therapeutic approaches over time, including i) agents with broad immunomodulatory effects, such as immunomodulatory drugs, ii) currently approved and next-generation monoclonal antibodies, and iii) immunotherapeutic strategies aiming at activating or administering immune effector cells specifically targeting leukemic cells (e.g. bi-or tri-specific antibodies, tumor vaccines, chimeric antigen receptor T cells, and checkpoint inhibitors).

Preservation of cell-based immunotherapies for clinical trials

In the unique supply chain of cellular therapies, preservation is important to keep the cell product viable. Many factors in cryopreservation affect the outcome of a cell therapy: (i) formulation and introduction of a freezing medium, (ii) cooling rate, (iii) storage conditions, (iv) thawing conditions and (v) post-thaw processing. This article surveys clinical trials of cellular immunotherapy that used cryopreserved regulatory, chimeric antigen receptor or gamma delta T cells, dendritic cells or natural killer (NK) cells. Several observations are summarized from the given information. The aforementioned cell types have been similarly frozen in media containing 5-10% dimethyl sulfoxide (DMSO) with plasma, serum or human serum albumin. Two common freezing methods are an insulated freezing container such as Nalgene Mr. Frosty and a controlled-rate freezer at a cooling rate of -1°C/min. Water baths at approximately 37°C have been commonly used for thawing. Post-thaw processing of cryopreserved cells varied greatly: some studies infused the cells immediately upon thawing; some diluted the cells in a carrier solution of varying formulation before infusion; some washed cells to remove cryoprotective agents; and others re-cultured cells to recover cell viability or functionality lost due to cryopreservation. Emerging approaches to preserving cellular immunotherapies are also described. DMSO-free formulations of the freezing media have demonstrated improved preservation of cell viability in T lymphocytes and of cytotoxic function in natural killer cells. Saccharides are a common type of molecule used as an alternative cryoprotective agent to DMSO. Improving methods of preservation will be critical to growth in the clinical use of cellular immunotherapies.

Lenalidomide as immune adjuvant to a dendritic cell vaccine in chronic lymphocytic leukemia patients

OBJECTIVES

We previously showed that immunization with ex vivo- generated autologous dendritic cells loaded with apoptotic tumor cells (Apo-DC) potentiated tumor-specific immunity in chronic lymphocytic leukemia (CLL) patients. Here, we evaluated safety and immunogenicity of Apo-DC in combination with lenalidomide, granulocyte-macrophage colony-stimulating factor (GM-CSF), and low-dose cyclophosphamide (CTX).

METHODS

Ten previously untreated patients with slowly progressing CLL received 5 Apo-DC vaccinations and lenalidomide orally for 24 weeks either alone (cohort I, n = 5) or together with subcutaneous GM-CSF and intravenous CTX (cohort II, n = 5). Tumor-specific T-cell responses were measured by proliferation and IFN-γ ELISPOT assays. Immune monitoring was performed by flow cytometry.

RESULTS

Dose-limiting toxicity was observed in 3/10 patients, 2 in cohort I and one in cohort II. One patient developed autoimmune hemolytic anemia and another grade 4 thrombocytopenia. Vaccine-induced immune responses were seen in 5/5 and 4/5 patients in cohort I and II, respectively. The expression of immune checkpoints on T cells did not change significantly.

CONCLUSIONS

Lenalidomide alone or in combination with GM-CSF and low-dose CTX as immune adjuvant to the Apo-DC vaccine elicited tumor-specific T-cell responses in CLL patients. However, unexpected toxicity was observed and caution is suggested in further exploring this drug as immune adjuvant in CLL.

Enhanced stimulation of human tumor-specific T cells by dendritic cells matured in the presence of interferon-γ and multiple toll-like receptor agonists

Dendritic cell (DC) vaccines have been demonstrated to elicit immunological responses in numerous cancer immunotherapy trials. However, long-lasting clinical effects are infrequent. We therefore sought to establish a protocol to generate DC with greater immunostimulatory capacity. Immature DC were generated from healthy donor monocytes by culturing in the presence of IL-4 and GM-CSF and were further differentiated into mature DC by the addition of cocktails containing different cytokines and toll-like receptor (TLR) agonists. Overall, addition of IFNγ and the TLR7/8 agonist R848 during maturation was essential for the production of high levels of IL-12p70 which was further augmented by adding the TLR3 agonist poly I:C. In addition, the DC matured with IFNγ, R848, and poly I:C also induced upregulation of several other pro-inflammatory and Th1-skewing cytokines/chemokines, co-stimulatory receptors, and the chemokine receptor CCR7. For most cytokines and chemokines the production was even further potentiated by addition of the TLR4 agonist LPS. Concurrently, upregulation of the anti-inflammatory cytokine IL-10 was modest. Most importantly, DC matured with IFNγ, R848, and poly I:C had the ability to activate IFNγ production in allogeneic T cells and this was further enhanced by adding LPS to the cocktail. Furthermore, epitope-specific stimulation of TCR-transduced T cells by peptide- or whole tumor lysate-loaded DC was efficiently stimulated only by DC matured in the full maturation cocktail containing IFNγ and the three TLR ligands R848, poly I:C, and LPS. We suggest that this cocktail is used for future clinical trials of anti-cancer DC vaccines.

A phase I clinical trial combining dendritic cell vaccination with adoptive T cell transfer in patients with stage IV melanoma

Adoptive transfer of in vitro-expanded tumor-infiltrating lymphocytes (TIL) has shown great clinical benefit in patients with malignant melanoma. TIL therapy itself has little side effects, but conditioning chemo- or radiotherapy and postinfusion interleukin 2 (IL-2) injections are associated with severe adverse advents. We reasoned that combining TIL infusion with dendritic cell (DC) vaccination could circumvent the need for conditioning and IL-2 support and thus represent a milder treatment approach. Eight patients with stage IV melanoma were enrolled in the MAT01 study, consisting of vaccination with autologous tumor-lysate-loaded DC, followed by TIL infusion. Six of eight patients were treated according to protocol, while one patient received only TIL and one only DC. Treatments were well tolerated with a single grade 3 adverse event. The small study size precludes analysis of clinical responses, though interestingly one patient showed a complete remission and two had stable disease. Analysis of the infusion products revealed that mature DC were generated in all cases. TIL after expansion were CD3+ T cells, dominated by effector memory CD8+ cytotoxic T cells. Analysis of the T cell receptor repertoire revealed presence of highly dominant clones in most infusion products, and many of these could be detected in the circulation for weeks after T cell transfer. Here, we report the first combination of DC vaccination and TIL infusion in malignant melanoma. This combined treatment was safe and feasible, though after evaluating both clinical and immunological parameters, we expect that administration of lymphodepleting chemotherapy and IL-2 will likely increase treatment efficacy.

Complex evaluation of human monocyte-derived dendritic cells for cancer immunotherapy

Dendritic cell (DC) immunotherapy is capable of generating tumour-specific immune responses. Different maturation strategies were previously tested to obtain DC capable of anti-cancer responses in vitro, usually with limited clinical benefit. Mutual comparison of currently used maturation strategies and subsequent complex evaluation of DC functions and their stimulatory capacity on T cells was performed in this study to optimize the DC vaccination strategy for further clinical application. DC were generated from monocytes using granulocyte–macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4, pulsed with whole tumour cell lysate and then matured with one of five selected maturation strategies or cultured without additional maturation stimulus. DC were characterized with regard to their surface marker expression, cytokine profiles, migratory capacity, allogeneic and autologous T cell stimulatory capacity as well as their specific cytotoxicity against tumour antigens. We were able to demonstrate extensive variability among different maturation strategies currently used in DC immunotherapeutic protocols that may at least partially explain limited clinical benefit of some clinical trials with such DC. We identified DC matured with interferon-γ and lipopolysaccharide as the most attractive candidate for future clinical trials in cancer immunotherapy.

Novel and emerging therapies safeguarding health of humans and their companion animals: a review

Modern medicine has helped to a great extent to eradicate and cure several diseases of mankind and animals. But the existence of incurable diseases like cancer, Acquired Immunodeficiency Syndrome (AIDS), diabetes or rheumatoid arthritis, side effects of allopathic medicine, increasing trend of antibiotic resistance and chemicals and biopesticides causing dietary risk have made the situation more critical than ever before. Thus, it has become a matter of concern for the scientists and researchers to develop novel therapies. Bacteriophage therapy to treat pathogenic bacterial infections, virophage therapy for conservation of global system and avian egg yolk antibody therapy for designing prophylactic strategies against Gastrointestinal (GI) diseases are interesting approaches. Others include the use of cytokines as adjunctive immunomodulators, gene therapy focusing on diseases caused by single gene defects, RNAi technology to suppress specific gene of interest and apoptins for cancer treatment. Stem cell therapy against several diseases and ailments has also been discussed. The use of nanoparticles for better drug delivery, even though costly, has been given equal importance. Nevertheless, immunomodulation, be it through physiological, chemical or microbial products, or through essential micronutrients, probiotics, herbs or cow therapy prove to be cost-effective, causing minimum adverse reactions when compared to allopathy. Development in the field of molecular biology has created an enormous impact on vaccine development. The present review deals with all these novel and emerging therapies essential to safeguard the health of humans and companion animals.

Vaccination with dendritic cells loaded with tumor apoptotic bodies (Apo-DC) in patients with chronic lymphocytic leukemia: effects of various adjuvants and definition of immune response criteria

We previously demonstrated that autologous dendritic cells that have endocytosed apoptotic bodies of chronic lymphocytic leukemia (CLL) cells (Apo-DC) can stimulate antileukemic T cell responses in vitro. In this phase I study, we vaccinated 15 asymptomatic CLL patients at five time points with Apo-DC administered intradermally either alone (cohort I), or in combination with subcutaneous granulocyte-macrophage-colony-stimulating-factor (GM-CSF) (cohort II) or with GM-CSF and intravenous low-dose cyclophosphamide (cohort III). Aim of the study was to evaluate the safety and immunogenicity of Apo-DC alone or in combination with GM-CSF and low-dose cyclophosphamide in CLL patients. All patients completed the vaccination schedule without dose-limiting toxicity. No objective clinical responses were seen. Vaccine-induced leukemia-specific immune responses were evaluated by IFN-γ ELISpot and proliferation assays over a 52 weeks observation period and immune response criteria were defined. According to these criteria, 10/15 patients were defined as immune responders. The frequency of immune-responding patients was higher in cohorts II (3/5) and III (5/5) than in cohort I (2/5). In order to further characterize the induced immune response, estimation of secreted cytokines and CD107-degranulation assay were performed. Clustering of T and CLL cells was observed in CD107-degranulation assay and visualized by confocal microscopy. Additionally, assessment of regulatory T cells (T(regs)) revealed their significantly lower frequencies in immune responders versus non-responders (P < 0.0001). Cyclophosphamide did not reduce T(regs) frequency. In conclusion, vaccination with Apo-DC + GM-CSF and cyclophosphamide was safe and elicited anti-CLL immune responses that correlated inversely with T(regs) levels. Lack of clinical responses highlights the necessity to develop more potent vaccine strategies in B cell malignancies.

Definition of a target for immunotherapy and results of the first Peptide vaccination study in chronic lymphocytic leukemia

Results of bone marrow transplantation, as well as remission phenomena after viral infections, suggest that chronic lymphocytic leukemia (CLL) might be targeted effectively by T-cell-based immunotherapy. Antigen-targeted immunotherapies represent novel treatments for CLL patients. Earlier, we screened the mRNA expression of several tumor associated antigens (TAAs), observing the presence of RHAMM/CD168, fibromodulin, syntaxin, and NY-Ren60 in 55%-90% of CLL patients. RHAMM/CD168, fibromodulin, PRAME, and MPP11 were expressed in CLL patients but not in healthy volunteers. Quantitative reverse transcriptase polymerase chain reaction revealed higher RHAMM expression in high-risk CLL patients as well as in advanced stages of the disease. CLL cases with higher RHAMM expressions showed significantly shorter median treatment-free survivals. Among patients with mutated IgVH genes, an analysis of RHAMM expression enabled us to distinguish a subgroup of patients with a favorable prognosis. In lymph nodes, RHAMM staining correlated with a higher Ki-67 index and CD40L expression. Functionally, stimulation with CD40L enhanced RHAMM expression in CLL. Because of the exquisite tissue expression of RHAMM and its high expression frequency in CLL patients, we further characterized RHAMM-specific CD8+ T cells in these patients. CD8+ T cells primed with the RHAMM-derived epitope R3, which is restricted by human leukocyte antigen (HLA)A2, lysed RHAMM+ CLL cells. Therefore, we initiated a Phase I clinical trial of R3 peptide vaccination. Four patients exhibited reduced white blood cell counts during the vaccination process. In 5/6 patients, R3-specific CD8+ T cells were detected with the corresponding peptide/HLA-A2 tetrameric complex; these populations were verified functionally in 4/5 patients using ELISpot assays. In conclusion, RHAMM expression seems to be of prognostic value, and may reflect the proliferative capacity of CLL cells; it may therefore represent an interesting target for immunotherapy. Peptide vaccination in CLL patients was safe eliciting specific CD8+ T-cell responses against the tumor antigen RHAMM.

Human myeloid dendritic cells for cancer therapy: does maturation matter?

Dendritic cells form the connection between innate and adoptive mechanisms of the immune system. As antigen-presenting cells, dendritic cells are capable of presenting tumour antigen and effectively stimulating immune response targeted against a tumour. A number of preclinical and clinical studies document dendritic cells' potential in anti-cancer treatment. Increasing knowledge of dendritic cell biology is leading to improved methods for their preparation for clinical application. Unfortunately, there is to date no consensus specifying optimal conditions for dendritic cell preparation in vitro. This review summarizes the methods used for preparing myeloid dendritic cells derived from monocytic precursors while focusing on cytokine cocktails used for their growth, maturation, and functional adjustment.