Advances in siRNA delivery strategies for the treatment of MDR cancer

RNA interference (RNAi) represents a promising therapeutic method that uses siRNA for cancer treatment. Although the RNAi technique has been increasingly used for clinical trials, systemic siRNA delivery into targeted cells is still challenging. The barriers impeding siRNA therapeutics delivery and impacting the treatment outcome must overcome with negligible systemic toxicity for a desirable and successful delivery of siRNA to MDR cancer cells. Nano delivery strategies have been investigated for nanocarrier functionalization, cancer immunotherapy and cancer targeting. Lipid nanoparticles (LNPs), dynamic polyconjugates (DPC™), GalNAc-siRNA conjugates, exosome and RBC systems have shown potential for efficient delivery of siRNA to cancer cells. Delivery of siRNA to tumor cells, immune cells to regulate T cell functions for immunotherapy are promising approaches.

Manipulation of Inflammasome: A Promising Approach Towards Immunotherapy of Lung Cancer

Chronic inflammation has emerged as a key player at different stages of cancer development. A prominent signaling pathway for acute and chronic inflammation is the activation of the caspase-1 inflammasomes. These are complexes that assemble on activation of certain nucleotide-binding domain, leucine-rich repeat containing proteins (NLRs), AIM2-like receptors (ALRs), or pyrin due to activation via PAMPs or DAMPs. Of these, five complexes-NLRP1, NLRP3, NLRC4, Pyrin, and AIM2 are of importance in the context of cancer for their activities in modulating immune responses, cell proliferation, and apoptosis. Inflammasomes have emerged as clinically relevant in multiple forms of cancer making them highly promising targets for cancer therapy. As lungs are a tissue niche that is prone to inflammation owing to its exposure to external substances, inflammasomes play a vital role in the development and pathogenesis of lung cancer. Therefore, manipulation of inflammasome by various immunomodulatory means could prove a full-proof strategy for the treatment of lung cancer. Here, in this review, we tried to explore the various strategies to target the inflammasomes for the treatment of lung cancer.

Salmonella-Based Therapy Targeting Indoleamine 2,3-Dioxygenase Restructures the Immune Contexture to Improve Checkpoint Blockade Efficacy

Therapeutic options for non-small cell lung cancer (NSCLC) treatment have changed dramatically in recent years with the advent of novel immunotherapeutic approaches. Among these, immune checkpoint blockade (ICB) using monoclonal antibodies has shown tremendous promise in approximately 20% of patients. In order to better predict patients that will respond to ICB treatment, biomarkers such as tumor-associated CD8⁺ T cell frequency, tumor checkpoint protein status and mutational burden have been utilized, however, with mixed success. In this study, we hypothesized that significantly altering the suppressive tumor immune landscape in NSCLC could potentially improve ICB efficacy. Using sub-therapeutic doses of our Salmonella typhimurium-based therapy targeting the suppressive molecule indoleamine 2,3-dioxygenase (shIDO-ST) in tumor-bearing mice, we observed dramatic changes in immune subset phenotypes that included increases in antigen presentation markers, decreased regulatory T cell frequency and overall reduced checkpoint protein expression. Combination shIDO-ST treatment with anti-PD-1/CTLA-4 antibodies enhanced tumor growth control, compared to either treatment alone, which was associated with significant intratumoral infiltration by CD8⁺ and CD4⁺ T cells. Ultimately, we show that increases in antigen presentation markers and infiltration by T cells is correlated with significantly increased survival in NSCLC patients. These results suggest that the success of ICB therapy may be more accurately predicted by taking into account multiple factors such as potential for antigen presentation and immune subset repertoire in addition to markers already being considered. Alternatively, combination treatment with agents such as shIDO-ST could be used to create a more conducive tumor microenvironment for improving responses to ICB.

Recent progress in nanomaterials for nucleic acid delivery in cancer immunotherapy

The combination of gene therapy and immunotherapy has the potential to systemically promote anti-tumor effects while reducing adverse reactions. Small interfering RNA (siRNA) has generated great interest in biology, engineering and medicine, especially for cancer treatment due to its ability to knock down genes of interest. Nanomaterials play significant roles in the design of delivery systems of siRNA, and nanomaterial-mediated siRNA delivery in cancer immunotherapy is one of the most important directions for future clinical cancer treatment. Here, we review the recent advances in nanomaterial mediated targeted delivery of siRNA to dendritic cells (DCs), tumor-associated macrophages (TAMs), immune checkpoint inhibitors, B lymphocytes, natural killer cells (NKs), and immunosuppressive cytokines. Fundamental challenges in nucleic acid delivery enabled by bio-barriers, its promising solution strategies and future directions are also reviewed.

Primer on immuno-oncology and immune response

Advances in the understanding of the immunogenicity of tumors have provided the basis for immuno-oncology, the development of immunotherapeutic agents that augment the patient's antitumor immunity and disrupt the immune-regulatory circuits that allow tumors to evade the immune system. Two immunomodulatory agents recently have been introduced for the treatment of malignancy: sipuleucel-T and ipilimumab. Unlike cytotoxic chemotherapy, immunotherapies stimulate the patient's immune system to mount or augment existing endogenous antitumor immune responses. Both agents have demonstrated significant improvements in long-term overall survival in patients. Like other immunotherapies, sipuleucel-T and ipilimumab also are characterized by adverse events that manifest as immune-related inflammatory conditions that typically are low grade. Management guidelines have been developed and emphasize early recognition of the signs and symptoms of immune-related adverse events and treatment with corticosteroids. Because these events can manifest even after the cessation of therapy, patients treated with immunotherapies should continue to be followed by their oncology team and other healthcare providers.

Ipilimumab in patients with cancer and the management of dermatologic adverse events

Ipilimumab is a fully human monoclonal antibody that blocks cytotoxic T-lymphocyte antigen-4 to augment antitumor T-cell responses. Phase III studies have demonstrated survival benefit in both previously treated and treatment-naïve patients with metastatic melanoma. In clinical trials, adverse events (AEs) related to treatment with ipilimumab were mostly grade 1/2 (as per Common Terminology Criteria for AEs, Version 4.02), and mostly reversible with appropriate management. Distinct immune-related AEs that may reflect the mechanism of action of ipilimumab have been identified, and occur commonly in the skin, typically presenting as a maculopapular rash, which can be accompanied by pruritus, pruritus with no skin lesions, alopecia, and vitiligo. Histologic analyses have revealed epidermal spongiosis, and perivascular CD4(+) T-cell infiltrates with some eosinophils in areas of rash. Timely implementation of toxicity-specific treatment guidelines that emphasize vigilance and early intervention allows mitigation of dermatologic AEs. Adherence to guidelines is necessary to maintain quality of life, ensure consistent dosing, and obtain the best possible clinical outcome.

New Approaches in Immunotherapy for the Treatment of Lung Cancer

Despite the several advances in the last few years into treatment of advanced lung cancer, the 5-year survival remains extremely low. New therapeutic strategies are currently under investigation, and immunotherapy seems to offer a promising treatment alternative. In the last decade, therapeutic cancer vaccines in lung cancer have been rather disappointing, mainly due to the lack of efficient predictive biomarkers. A better refinement of the patient population that might respond to treatment might finally lead to a success story. For the first time, the immune checkpoint inhibitors are demonstrating sustained antitumor response and improved survival and they may be the first immunotherapeutics available for patients with lung cancer.

Comprehensive genomic characterization of squamous cell lung cancers

Lung squamous cell carcinoma is a common type of lung cancer, causing approximately 400,000 deaths per year worldwide. Genomic alterations in squamous cell lung cancers have not been comprehensively characterized, and no molecularly targeted agents have been specifically developed for its treatment. As part of The Cancer Genome Atlas, here we profile 178 lung squamous cell carcinomas to provide a comprehensive landscape of genomic and epigenomic alterations. We show that the tumour type is characterized by complex genomic alterations, with a mean of 360 exonic mutations, 165 genomic rearrangements, and 323 segments of copy number alteration per tumour. We find statistically recurrent mutations in 11 genes, including mutation of TP53 in nearly all specimens. Previously unreported loss-of-function mutations are seen in the HLA-A class I major histocompatibility gene. Significantly altered pathways included NFE2L2 and KEAP1 in 34%, squamous differentiation genes in 44%, phosphatidylinositol-3-OH kinase pathway genes in 47%, and CDKN2A and RB1 in 72% of tumours. We identified a potential therapeutic target in most tumours, offering new avenues of investigation for the treatment of squamous cell lung cancers.

Immune alterations and emerging immunotherapeutic approaches in lung cancer

INTRODUCTION

Subjects with lung cancer were shown to present a variety of immune abnormalities including cellular immune dysfunction, cytokine alterations, and antigen presentation defects. As discouraging results are commonly seen with the existing therapies in lung cancer, more innovative treatment strategies are needed.

AREAS COVERED

The authors review comprehensively the immune abnormalities in individuals with lung cancer, describe the lung cancer immunotherapy candidates that are most advanced in their clinical development, and summarize recent data from clinical trials of these agents.

EXPERT OPINION

Enhancing the immune system represents an appealing avenue for lung cancer therapy. Several immunomodulating agents have activity in this regard including ipilimumab, a monoclonal antibody against the CTLA-4, and talactoferrin, a dendritic cell activator. In addition, a significant activity was shown with belagenpumatucel-L, a whole-cell-based vaccine that blocks the action of TGF-β2. Other promising vaccines are protein-specific vaccines against tumor antigens such as MAGE-A3, EGF, and MUC1. Although some of these immunotherapies may have lackluster performance as single agents in advanced disease, more impressive results are seen in combination with chemotherapy agents. Given their proven activity in lung cancer, these immunotherapies may soon become a powerful addition to the oncologist's toolbox.

Molecular profiling to optimize treatment in non-small cell lung cancer: a review of potential molecular targets for radiation therapy by the translational research program of the radiation therapy oncology group

Therapeutic decisions in non-small cell lung cancer (NSCLC) have been mainly based on disease stage, performance status, and co-morbidities, and rarely on histological or molecular classification. Rather than applying broad treatments to unselected patients that may result in survival increase of only weeks to months, research efforts should be, and are being, focused on identifying predictive markers for molecularly targeted therapy and determining genomic signatures that predict survival and response to specific therapies. The availability of such targeted biologics requires their use to be matched to tumors of corresponding molecular vulnerability for maximum efficacy. Molecular markers such as epidermal growth factor receptor (EGFR), K-ras, vascular endothelial growth factor (VEGF), mammalian target of rapamycin (mTOR), and anaplastic lymphoma kinase (ALK) represent potential parameters guide treatment decisions. Ultimately, identifying patients who will respond to specific therapies will allow optimal efficacy with minimal toxicity, which will result in more judicious and effective application of expensive targeted therapy as the new paradigm of personalized medicine develops.

Hypophysitis induced by monoclonal antibodies to cytotoxic T lymphocyte antigen 4: challenges from a new cause of a rare disease

Specific human monoclonal antibodies antagonize cytotoxic T-lymphocyte antigen 4 (anti-CTLA-4 mAbs), a negative regulator of the immune system, inducing unrestrained T-cell activation. In patients with advanced or metastatic melanoma, one of these agents, ipilimumab, produced considerable disease control rates and, for the first time, a clear improvement in overall survival outcomes. However, accumulating clinical experience with anti-CTLA-4 mAbs identified a novel syndrome of autoimmune and autoinflammatory side effects, designated as "immune-related adverse events," including mainly rash, colitis, and hepatitis. Autoimmune hypophysitis has emerged as a distinctive side effect induced by anti-CTLA-4 mAbs. This condition may be life threatening because of adrenal insufficiency if not promptly recognized, but it may easily be diagnosed and treated if clinically suspected. Hypopituitarism caused by these agents is rarely reversible and prolonged or life-long substitutive hormonal treatment is often required. The precise mechanism of injury to the pituitary triggered by anti-CTLA-4 mAbs is yet to be fully elucidated.

The secret ally: immunostimulation by anticancer drugs

It has recently become clear that the tumour microenvironment, and in particular the immune system, has a crucial role in modulating tumour progression and response to therapy. Indicators of an ongoing immune response, such as the composition of the intratumoural immune infiltrate, as well as polymorphisms in genes encoding immune modulators, have been correlated with therapeutic outcome. Moreover, several anticancer agents--including classical chemotherapeutics and targeted compounds--stimulate tumour-specific immune responses either by inducing the immunogenic death of tumour cells or by engaging immune effector mechanisms. Here, we discuss the molecular and cellular circuitries whereby cytotoxic agents can activate the immune system against cancer, and their therapeutic implications.

Ipilimumab: a novel immunostimulatory monoclonal antibody for the treatment of cancer

Ipilimumab (Yervoy, developed by Medarex and Bristol-Myers Squibb) is a fully human monoclonal IgG1κ antibody against the cytotoxic T-lymphocyte antigen-4 (CTLA-4), an immune-inhibitory molecule expressed in activated T cells and in suppressor T regulatory cells. Interaction of the monoclonal antibody with CTLA-4 blocks inhibitory signals generated through this receptor and enhances T cell activation, leading to increased antitumor responses. Ipilimumab has been approved by FDA in March 2011 as monotherapy (3mg/kg every 3 weeks for 4 doses) for the treatment of advanced (unresectable or metastatic) melanoma both in pre-treated or chemotherapy naïve patients. Four months later, ipilimumab has received a rapid approval by the European Commission, after a positive opinion from the Committee for Medicinal Products for Human Use. However, the indication in the EU is limited to previously-treated patients with advanced melanoma. Ipilimumab is the first agent that has demonstrated to improve overall survival in patients with metastatic melanoma, which has a very poor prognosis, in randomized phase III clinical trials. The patterns of tumour response to ipilimumab differ from those observed with cytotoxic chemotherapeutic agents, since patients may have a delayed yet durable response and obtain long-term survival benefit despite an initial tumour growth. The major draw-back of ipilimumab is the induction of immune-related adverse effects; the latter can be life-threatening, unless promptly managed with immunosuppressive agents (most frequently corticosteroids) according to specific guidelines. Further development of ipilimumab includes its use in the neoadjuvant or adjuvant high-risk melanoma setting and for the treatment of other refractory and advanced solid tumours, either as single agent or in combination with additional immunostimulating agents or molecularly targeted therapies.

Cytotoxic T-lymphocyte-associated antigen-4

Cancer immunotherapy relies on the ability of the immune system to target tumor-specific antigens to generate an immune response. This initial response requires both binding of the MHC/antigen peptide to T-cell receptor complex, along with a second costimulatory signal created by the binding of CD28 on the T cell, with B7 located on the antigen-presenting cell. Regulatory checkpoints, such as cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), serve to attenuate this signal, thereby preventing autoimmunity. Its key role in regulating the immune system has made CTLA-4 an attractive therapeutic target for cancer, with the development of fully human monoclonal antibodies that have successfully targeted CTLA-4 in clinical trials. Augmentation of the immune response via blockade of CTLA-4 represents a significant advance in the field of oncology and has shown an improvement in survival for patients with metastatic melanoma. An increased understanding of the components of this pathway and the identification of other methods to modulate the immune system hold great promise for future therapy.

CTLA-4 blockade increases antigen-specific CD8(+) T cells in prevaccinated patients with melanoma: three cases

BACKGROUND

Anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) antibodies, such as ipilimumab, have generated measurable immune responses to Melan-A, NY-ESO-1, and gp100 antigens in metastatic melanoma. Vaccination against such targets has potential for immunogenicity and may produce an effector-memory T-cell response.

METHODS

To determine the effect of CTLA-4 blockade on antigen-specific responses following vaccination, in-depth immune monitoring was performed on three ipilimumab-treated patients prevaccinated with gp100 DNA (IMF-24), gp100(209-217) and tyrosinase peptides plus GM-CSF DNA (IMF-32), or NY-ESO-1 protein plus imiquimod (IMF-11); peripheral blood mononuclear cells were analyzed by tetramer and/or intracellular cytokine staining following 10-day culture with HLA-A*0201-restricted gp100(209-217) (ITDQVPFSV), tyrosinase(369-377) (YMDGTMSQV), or 20-mer NY-ESO-1 overlapping peptides, respectively. Tumors from IMF-32 were analyzed by immunohistochemistry to help elucidate mechanism(s) underlying tumor escape.

RESULTS

Following vaccination, patients generated weak to no CD4(+) or CD8(+) T-cell response specific to the vaccine antigen but demonstrated increases in effector-memory (CCR7(lo)CD45RA(lo)) tetramer(+)CD8(+) T cells. After ipilimumab induction, patients experienced a robust, although sometimes transient, antigen-specific response for gp100 (IMF-32 and IMF-24) or NY-ESO-1 (IMF-11) and produced polyfunctional intracellular cytokines. Primary and metastatic tumors expressed tyrosinase but not gp100 or class I/II MHC molecules.

CONCLUSION

Vaccination induced a measurable antigen-specific T-cell response that increased following CTLA-4 blockade, potentially "boosting" the vaccine-primed response. Tumor escape may be related to antigen loss or lack of MHC expression necessary for immune activity. These results in a limited number of patients support the need for further research into combining vaccination with ipilimumab and provide insight into mechanisms underlying tumor escape.

Clinical studies with anti-CTLA-4 antibodies in non-melanoma indications

Available medical treatments have limited impact on the survival of patients with advanced cancer; therefore, new therapeutic strategies able to generate more effective host's immune responses against neoplastic cells are being actively pursued. Among these, a recent approach involves targeting of cytotoxic T-lymphocyte antigen-4 (CTLA-4), a key immune checkpoint molecule, by monoclonal antibodies (mAbs). Ipilimumab and tremelimumab represent the prototypes of this new class of immunomodulating mAb and have been extensively tested in metastatic melanoma with highly promising results. The clinical activity observed in melanoma has served as a model to exploit the therapeutic potential of CTLA-4 blockade in a variety of human malignancies. Along this line, early-phase trials with anti-CTLA-4 mAbs have been completed or are ongoing in tumors of different histotype. Results are demonstrating the feasibility, safety, and activity of these agents, thus suggesting a promising therapeutic role to be further investigated in phase II/III trials in a wide range of tumors. This review summarizes the main trials with ipilimumab and tremelimumab in tumors of different histotypes, excluding cutaneous melanoma, which is extensively described in other chapters of this issue of Seminars in Oncology.

Ipilimumab: unleashing the power of the immune system through CTLA-4 blockade

Malignant melanoma is rising faster in incidence than any other malignancy. Long-term remission or "cure" is rare and is almost exclusively limited to therapies that stimulate an immune antitumor response. Ipilimumab is a novel targeted human immunostimulatory monoclonal antibody that blocks cytotoxic T-lymphocyte antigen4 (CTLA-4), an immune-inhibitory site expressed on activated T cells. Ipilimumab is well tolerated as an outpatient infusion therapy. Multiple studies have confirmed significant antimelanoma activity. A randomized trial has documented a survival benefit when ipilimumab was compared to a gp-100 vaccine only arm. The unique mechanism of action of ipilimumab makes assessment of response by conventional criteria difficult. Benefit from ipilimumab can occur after what would be considered progression with World Health Oganization (WHO) or Response Evaluation Criteria in Solid Tumors (RECIST) criteria. New immune response criteria have been proposed. Therapeutic responses peak between 12 and 24 weeks, with slow responses continuing up to and beyond 12 months. The major drug- related adverse side effects (10%-15% grade 3 or above) are immune-related and consist most commonly of rash, colitis, hypophysitis, thyroiditis, and hepatitis. Colonic perforation can occur and patients with diarrhea have to be monitored carefully with strict adherence to treatment algorithms. Algorithms for the treatment of other adverse side effects have been developed. The treatment of immune-related side effects with immunosuppressive agents, such as corticosteroids, does not appear to impair antitumor response. With proper monitoring and management of side effects, ipilimumab is an extremely safe drug to administer. The benefits of ipilimumab will most certainly extend to other malignancies in the near future.