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

Reshaping the tumor microenvironment: The versatility of immunomodulatory drugs in B-cell neoplasms

Immunomodulatory drugs (IMiDs) such as thalidomide, lenalidomide and pomalidomide are antitumor compounds that have direct tumoricidal activity and indirect effects mediated by multiple types of immune cells in the tumor microenvironment (TME). IMiDs have shown remarkable therapeutic efficacy in a set of B-cell neoplasms including multiple myeloma, B-cell lymphomas and chronic lymphocytic leukemia. More recently, the advent of immunotherapy has revolutionized the treatment of these B-cell neoplasms. However, the success of immunotherapy is restrained by immunosuppressive signals and dysfunctional immune cells in the TME. Due to the pleiotropic immunobiological properties, IMiDs have shown to generate synergetic effects in preclinical models when combined with monoclonal antibodies, immune checkpoint inhibitors or CAR-T cell therapy, some of which were successfully translated to the clinic and lead to improved responses for both first-line and relapsed/refractory settings. Mechanistically, despite cereblon (CRBN), an E3 ubiquitin ligase, is considered as considered as the major molecular target responsible for the antineoplastic activities of IMiDs, the exact mechanisms of action for IMiDs-based TME re-education remain largely unknown. This review presents an overview of IMiDs in regulation of immune cell function and their utilization in potentiating efficacy of immunotherapies across multiple types of B-cell neoplasms.

Lenalidomide bypasses CD28 co-stimulation to reinstate PD-1 immunotherapy by activating Notch signaling

Programmed cell death protein 1 (PD-1) checkpoint blockade therapy requires the CD28 co-stimulatory receptor for CD8⁺ T cell expansion and cytotoxicity. However, CD28 expression is frequently lost in exhausted T cells and during immune senescence, limiting the clinical benefits of PD-1 immunotherapy in individuals with cancer. Here, using a cereblon knockin mouse model that regains in vivo T cell response to lenalidomide, an immunomodulatory imide drug, we show that lenalidomide reinstates the anti-tumor activity of CD28-deficient CD8⁺ T cells after PD-1 blockade. Lenalidomide redirects the CRL4^Crbn ubiquitin ligase to degrade Ikzf1 and Ikzf3 in T cells and unleashes paracrine interleukin-2 (IL-2) and intracellular Notch signaling, which collectively bypass the CD28 requirement for activation of intratumoral CD8⁺ T cells and inhibition of tumor growth by PD-1 blockade. Our results suggest that PD-1 immunotherapy can benefit from a lenalidomide combination when treating solid tumors infiltrated with abundant CD28^- T cells.

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).

A Perspective on Cell Therapy and Cancer Vaccine in Biliary Tract Cancers (BTCs)

Biliary tract cancer (BTC) is a rare, but aggressive, disease that comprises of gallbladder carcinoma, intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma, with heterogeneous molecular profiles. Advanced disease has limited therapeutic options beyond first-line platinum-based chemotherapy. Immunotherapy has emerged as a viable option for many cancers with a similar unmet need. Therefore, we reviewed current understanding of the tumor immune microenvironment and recent advances in cellular immunotherapy and therapeutic cancer vaccines against BTC. We illustrated the efficacy of dendritic cell vaccination in one patient with advanced, chemorefractory, melanoma-associated antigen (MAGE)-positive gallbladder carcinoma, who was given multiple injections of an allogenic MAGE antigen-positive melanoma cell lysate (MCL)-based autologous dendritic cell vaccine combined with sequential anti-angiogenic therapy. This resulted in good radiological and tumor marker response and an overall survival of 3 years from diagnosis. We postulate the potential synergism of adding anti-angiogenic therapy, such as bevacizumab, to immunotherapy in BTC, as a rational scientific principle to positively modulate the tumor microenvironment to augment antitumor immunity.

Recent Advances in Nanotechnology for Dendritic Cell-Based Immunotherapy

Dendritic cells (DCs) are the most important antigen-presenting cells that determine cancer immune responses by regulating immune activation and tolerance, especially in the initiation stage of specific responses. Manipulation of DCs to enhance specific antitumor immune response is considered to be a powerful tool for tumor eradication. Nanotechnology, which can incorporate multifunction components and show spatiotemporal control properties, is of great interest and is widely investigated for its ability to improve immune response activity against cancer and even for prevention and avoiding recurrence. In this mini-review, we aim to provide a general view of DC-based immunotherapy, including that involving the promising nanotechnology. Particularly we discuss: (1) manipulation or engineering of DCs for adoptive vaccination, (2) employing DCs as a combination to more existing therapeutics in tumor treatment, and (3) direct modulation of DCs in vivo to enhance antigen presentation efficacy and priming T cells subsequently. We comprehensively discuss the updates on the application of nanotechnology in DC-based immunotherapy and provide some insights on the challenges and opportunities of DC-based immunotherapeutics, including the potential of nanotechnology, against cancers.

Advances and perspectives of dendritic cell-based active immunotherapies in follicular lymphoma

Follicular lymphoma (FL) is a remarkably immune-responsive malignancy, which is still considered incurable. As, standard immunochemotherapy is complex, toxic and not curative, improvement in FL care is now a crucial topic in hemato-oncology. Recently, we and others have shown that dendritic cell (DC)-based therapies allow a specific immune response associated with sustained lymphoma regression in a proportion of low-tumor burden FL patients. Importantly, the rate of objective clinical response (33-50%) and of sustained remission is remarkably higher compared to similar studies in solid tumors, corroborating the assumption of the immune responsiveness of FL. Our experimental intra-tumoral strategy combined injection with rituximab and interferon-α-derived dendritic cells (IFN-DC), a novel DC population particularly efficient in biasing T-helper response toward the Th1 type and in the cross-priming of CD8 + T cells. Noteworthy, intra-tumoral injection of DC is a new therapeutic option based on the assumption that following the induction of cancer-cell immunogenic death, unloaded DC would phagocytize in vivo the tumor associated antigens and give rise to a specific immune response. This approach allows the design of easy and inexpensive schedules. On the other hand, advanced and straightforward methods to produce clinical-grade antigenic formulations are currently under development. Both unloaded DC strategies and DC-vaccines are suited for combination with radiotherapy, immune checkpoint inhibitors, immunomodulators and metronomic chemotherapy. In fact, studies in animal models have already shown impressive results, while early-phase combination trials are ongoing. Here, we summarize the recent advances and the future perspectives of DC-based therapies in the treatment of FL patients.

Lenalidomide improves the therapeutic effect of an interferon-α-dendritic cell-based lymphoma vaccine

The perspective of combining cancer vaccines with immunomodulatory drugs is currently regarded as a highly promising approach for boosting tumor-specific T cell immunity and eradicating residual malignant cells. The efficacy of dendritic cell (DC) vaccination in combination with lenalidomide, an anticancer drug effective in several hematologic malignancies, was investigated in a follicular lymphoma (FL) model. First, we evaluated the in vitro activity of lenalidomide in modulating the immune responses of lymphocytes co-cultured with a new DC subset differentiated with IFN-α (IFN-DC) and loaded with apoptotic lymphoma cells. We next evaluated the efficacy of lenalidomide and IFN-DC-based vaccination, either alone or in combination, in hu-PBL-NOD/SCID mice bearing established human lymphoma. We found that lenalidomide reduced Treg frequency and IL-10 production in vitro, improved the formation of immune synapses of CD8 + lymphocytes with lymphoma cells and enhanced anti-lymphoma cytotoxicity. Treatment of lymphoma-bearing mice with either IFN-DC vaccination or lenalidomide led to a significant decrease in tumor growth and lymphoma cell spread. Lenalidomide treatment was shown to substantially inhibit tumor-induced neo-angiogenesis rather than to exert a direct cytotoxic effect on lymphoma cells. Notably, the combined treatment with the vaccine plus lenalidomide was more effective than either single treatment, resulting in the significant regression of established tumors and delayed tumor regrowth upon treatment discontinuation. In conclusion, our data demonstrate that IFN-DC-based vaccination plus lenalidomide exert an additive therapeutic effect in xenochimeric mice bearing established lymphoma. These results may pave the way to evaluate this combination in the clinical ground.

Trial watch: dendritic cell vaccination for cancer immunotherapy

Dendritic- cells (DCs) have received considerable attention as potential targets for the development of anticancer vaccines. DC-based anticancer vaccination relies on patient-derived DCs pulsed with a source of tumor-associated antigens (TAAs) in the context of standardized maturation-cocktails, followed by their reinfusion. Extensive evidence has confirmed that DC-based vaccines can generate TAA-specific, cytotoxic T cells. Nonetheless, clinical efficacy of DC-based vaccines remains suboptimal, reflecting the widespread immunosuppression within tumors. Thus, clinical interest is being refocused on DC-based vaccines as combinatorial partners for T cell-targeting immunotherapies. Here, we summarize the most recent preclinical/clinical development of anticancer DC vaccination and discuss future perspectives for DC-based vaccines in immuno-oncology.

Can Dendritic Cell Vaccination Prevent Leukemia Relapse?

Leukemias are clonal proliferative disorders arising from immature leukocytes in the bone marrow. While the advent of targeted therapies has improved survival in certain subtypes, relapse after initial therapy is a major problem. Dendritic cell (DC) vaccination has the potential to induce tumor-specific T cells providing long-lasting, anti-tumor immunity. This approach has demonstrated safety but limited clinical success until recently, as DC vaccination faces several barriers in both solid and hematological malignancies. Importantly, vaccine-mediated stimulation of protective immune responses is hindered by the aberrant production of immunosuppressive factors by cancer cells which impede both DC and T cell function. Leukemias present the additional challenge of severely disrupted hematopoiesis owing to both cytogenic defects in hematopoietic progenitors and an abnormal hematopoietic stem cell niche in the bone marrow; these factors accentuate systemic immunosuppression and DC malfunction. Despite these obstacles, several recent clinical trials have caused great excitement by extending survival in Acute Myeloid Leukemia (AML) patients through DC vaccination. Here, we review the phenotype and functional capacity of DCs in leukemia and approaches to harness DCs in leukemia patients. We describe the recent clinical successes in AML and detail the multiple new strategies that might enhance prognosis in AML and other leukemias.

Molecular Interactions Between Innate and Adaptive Immune Cells in Chronic Lymphocytic Leukemia and Their Therapeutic Implications

Innate immunity constitutes the first line of host defense against various anomalies in humans, and it also guides the adaptive immune response. The function of innate immune components and adaptive immune components are interlinked in hematological malignancies including chronic lymphocytic leukemia (CLL), and molecular interactions between innate and adaptive immune components are crucial for the development, progression and the therapeutic outcome of CLL. In this leukemia, genetic mutations in B cells and B cell receptors (BCR) are key driving factors along with evasion of cytotoxic T lymphocytes and promotion of regulatory T cells. Similarly, the release of various cytokines from CLL cells triggers the protumor phenotype in macrophages that further edges the CLL cells. Moreover, under the influence of various cytokines, dendritic cells are unable to mature and trigger T cell mediated antitumor response. The phenotypes of these cells are ultimately controlled by respective signaling pathways, the most notables are BCR, Wnt, Notch, and NF-κB, and their activation affects the cytokine profile that controls the pathogenesis of CLL, and challenge its treatment. There are several novel substances for CLL under clinical development, including kinase inhibitors, antibodies, and immune-modulators that offer new hopes. DC-based vaccines and CAR T cell therapy are promising tools; however, further studies are required to precisely dissect the molecular interactions among various molecular entities. In this review, we systematically discuss the involvement, common targets and therapeutic interventions of various cells for the better understanding and therapy of CLL.

Trial Watch: Toll-like receptor agonists in cancer immunotherapy

Toll-like receptor (TLR) agonists demonstrate therapeutic promise as immunological adjuvants for anticancer immunotherapy. To date, three TLR agonists have been approved by US regulatory agencies for use in cancer patients. Additionally, the potential of hitherto experimental TLR ligands to mediate clinically useful immunostimulatory effects has been extensively investigated over the past few years. Here, we summarize recent preclinical and clinical advances in the development of TLR agonists for cancer therapy.