Talimogene laherparepvec (T-VEC) for the treatment of advanced melanoma

Combination therapy for cancer with oncolytic virus and checkpoint inhibitor: A mathematical model

Oncolytic virus (OV) is a replication competent virus that selectively invades cancer cells; as these cells die under the viral burden, the released virus particles proceed to infect other cancer cells. Oncolytic viruses are designed to also be able to stimulate the anticancer immune response. Thus, one may represent an OV by two parameters: its replication potential and its immunogenicity. In this paper we consider a combination therapy with OV and a checkpoint inhibitor, anti-PD-1. We evaluate the efficacy of the combination therapy in terms of the tumor volume at some later time, for example, 6 months from initial treatment. Since T cells kill not only virus-free cancer cells but also virus-infected cancer cells, the following question arises: Does increasing the amount of the checkpoint inhibitor always improve the efficacy? We address this question, by a mathematical model consisting of a system of partial differential equations. We use the model to construct, by simulations, an efficacy map in terms of the doses of the checkpoint inhibitor and the OV injection. We show that there are regions in the map where an increase in the checkpoint inhibitor actually decreases the efficacy of the treatment. We also construct efficacy maps with checkpoint inhibitor vs. the replication potential of the virus that show the same antagonism, namely, an increase in the checkpoint inhibitor may actually decrease the efficacy. These results have implications for clinical trials.

Intratumoral CD40 activation and checkpoint blockade induces T cell-mediated eradication of melanoma in the brain

CD40 agonists bind the CD40 molecule on antigen-presenting cells and activate them to prime tumor-specific CD8⁺ T cell responses. Here, we study the antitumor activity and mechanism of action of a nonreplicating adenovirus encoding a chimeric, membrane-bound CD40 ligand (ISF35). Intratumoral administration of ISF35 in subcutaneous B16 melanomas generates tumor-specific, CD8⁺ T cells that express PD-1 and suppress tumor growth. Combination therapy of ISF35 with systemic anti-PD-1 generates greater antitumor activity than each respective monotherapy. Triple combination of ISF35, anti-PD-1, and anti-CTLA-4 results in complete eradication of injected and noninjected subcutaneous tumors, as well as melanoma tumors in the brain. Therapeutic efficacy is associated with increases in the systemic level of tumor-specific CD8⁺ T cells, and an increased ratio of intratumoral CD8⁺ T cells to CD4⁺ Tregs. These results provide a proof of concept of systemic antitumor activity after intratumoral CD40 triggering with ISF35 in combination with checkpoint blockade for multifocal cancer, including the brain.

Treatment options for metastatic melanoma are limited. Here the authors show that combining an immunostimulant adenovirus, currently in clinical trials for leukemia, with immune checkpoints blockade (ICB) results in systemic eradication of ICB resistant melanoma tumours from both skin and brain of mice.

Skp2-Mediated Stabilization of MTH1 Promotes Survival of Melanoma Cells upon Oxidative Stress

MTH1 helps prevent misincorporation of ROS-damaged dNTPs into genomic DNA; however, there is little understanding of how MTH1 itself is regulated. Here, we report that MTH1 is regulated by polyubiquitination mediated by the E3 ligase Skp2. In melanoma cells, MTH1 was upregulated commonly mainly due to its improved stability caused by K63-linked polyubiquitination. Although Skp2 along with other components of the Skp1-Cullin-F-box (SCF) ubiquitin ligase complex was physically associated with MTH1, blocking the SCF function ablated MTH1 ubiquitination and expression. Conversely, overexpressing Skp2-elevated levels of MTH1 associated with an increase in its K63-linked ubiquitination. In melanoma cell lines and patient specimens, we observed a positive correlation of Skp2 and MTH1 expression. Mechanistic investigations showed that Skp2 limited DNA damage and apoptosis triggered by oxidative stress and that MAPK upregulated Skp2 and MTH1 to render cells more resistant to such stress. Collectively, our findings identify Skp2-mediated K63-linked polyubiquitination as a critical regulatory mechanism responsible for MTH1 upregulation in melanoma, with potential implications to target the MAPK/Skp2/MTH1 pathway to improve its treatment. Cancer Res; 77(22); 6226-39. ©2017 AACR.

Interaction of molecular alterations with immune response in melanoma

Major advances have been made in melanoma treatment with the use of molecularly targeted therapies and immunotherapies, and numerous regimens are now approved by the US Food and Drug Administration for patients with stage IV disease. However, therapeutic resistance remains an issue to both classes of agents, and reliable biomarkers of therapeutic response and resistance are lacking. Mechanistic insights are being gained through preclinical studies and translational research, offering potential strategies to enhance responses and survival in treated patients. A comprehensive understanding of the immune effects of common mutations at play in melanoma is critical, as is an appreciation of the molecular mechanisms contributing to therapeutic resistance to immunotherapy. These mechanisms and the interplay between them are discussed herein. Cancer 2017;123:2130-42. © 2017 American Cancer Society.

A practical guide to the handling and administration of talimogene laherparepvec in Europe

Talimogene laherparepvec is a herpes simplex virus-1-based intralesional oncolytic immunotherapy and is the first oncolytic virus to be approved in Europe. It is indicated for the treatment of adults with unresectable melanoma that is regionally or distantly metastatic (stage IIIB, IIIC, and IVM1a) with no bone, brain, lung, or other visceral disease. Talimogene laherparepvec is a genetically modified viral therapy, and its handling needs special attention due to its deep freeze, cold-chain requirements, its potential for viral shedding, and its administration by direct intralesional injection. This review provides a practical overview of handling, storage, and administration procedures for this agent in Europe. Talimogene laherparepvec vials should be transported/stored frozen at a temperature of −90°C to −70°C, and once thawed, vials must not be refrozen. Universal precautions for preparation, administration, and handling should be followed to avoid accidental exposure. Health care providers should wear personal protective equipment, and materials that come into contact with talimogene laherparepvec should be disposed of in accordance with local institutional procedures. Individuals who are immunocompromised or pregnant should not prepare or administer this agent. Talimogene laherparepvec is administered by intralesional injection into cutaneous, subcutaneous, and/or nodal lesions that are visible, palpable, or detectable by ultrasound. Treatment should be continued for ≥6 months. As with other immunotherapies, patients may experience an increase in the size of existing lesion(s) or the appearance of new lesions (ie, progression) prior to achieving a response (“pseudo-progression”). As several health care professionals (eg, physicians [dermatologists, surgeons, oncologists, radiologists], pharmacists, nurses) are involved in different stages of the process, there is a need for good interdisciplinary collaboration when using talimogene laherparepvec. Although there are specific requirements for this agent’s storage, handling, administration, and disposal, these can be effectively managed in a real-world clinical setting through the implementation of training programs and straightforward standard operating procedures.

Employing RNA viruses to fight cancer: novel insights into oncolytic virotherapy

Within recent decades, viruses that specifically target tumor cells have emerged as novel therapeutic agents against cancer. These viruses do not only act via their cell-lytic properties, but also harbor immunostimulatory features to re-direct the tumor microenvironment and stimulate tumor-directed immune responses. Furthermore, oncolytic viruses are considered to be superior to classical cancer therapies due to higher selectivity towards tumor cell destruction and, consequently, less collateral damage of non-transformed healthy tissue. In particular, the field of oncolytic RNA viruses is rapidly developing since these agents possess alternative tumor-targeting strategies compared to established oncolytic DNA viruses. Thus, oncolytic RNA viruses have broadened the field of virotherapy facilitating new strategies to fight cancer. In addition to several naturally occurring oncolytic viruses, genetically modified RNA viruses that are armed to express foreign factors such as immunostimulatory molecules have been successfully tested in early clinical trials showing promising efficacy. This review aims to provide an overview of the most promising RNA viruses in clinical development, to summarize the current knowledge of clinical trials using these viral agents, and to discuss the main issues as well as future perspectives of clinical approaches using oncolytic RNA viruses.

Combination of Plant Virus Nanoparticle-Based in Situ Vaccination with Chemotherapy Potentiates Antitumor Response

Immunotherapeutics are gaining more traction in the armamentarium used to combat cancer. Specifically, in situ vaccination strategies have gained interest because of their ability to alter the tumor microenvironment to an antitumor state. Herein, we investigate whether flexuous plant virus-based nanoparticles formed by the potato virus X (PVX) can be used as an immunotherapeutic for in situ vaccine monotherapy. We further developed dual chemo-immunotherapeutics by incorporating doxorubicin (DOX) into PVX yielding a dual-functional nanoparticle (PVX-DOX) or by coadministration of the two therapeutic regimes, PVX immunotherapy and DOX chemotherapy (PVX+DOX). In the context of B16F10 melanoma, PVX was able to elicit delayed tumor progression when administered as an intratumoral in situ vaccine. Furthermore, the coadministration of DOX via PVX+DOX enhanced the response of the PVX monotherapy through increased survival, which was also represented in the enhanced antitumor cytokine/chemokine profile stimulated by PVX+DOX when compared to PVX or DOX alone. Importantly, coadministered PVX+DOX was better for in situ vaccination than PVX loaded with DOX (PVX-DOX). Whereas the nanomedicine field strives to design multifunctional nanoparticles that integrate several functions and therapeutic regimens into a single nanoparticle, our data suggest a paradigm shift; some therapeutics may need to be administered separately to synergize and achieve the most potent therapeutic outcome. Altogether, our studies show that development of plant viral nanoparticles for in situ vaccines for treatment is a possibility, and dual mechanistic therapeutics can increase efficacy. Nonetheless, combining immunotherapeutics with cytolytic chemotherapy requires detailed investigation to inform optimal integration of cytolytic and immunotherapies and maximize synergy and efficacy.

The safety of talimogene laherparepvec for the treatment of advanced melanoma

INTRODUCTION

Talimogene laherparepvec (T-VEC, IMLYGIC) is an oncolytic herpes virus type I used as intralesional therapy for the treatment of unresectable metastatic melanoma in a cutaneous, subcutaneous, or nodal location. Talimogene laherparepvec selectively replicates within and lyses tumor cells while producing granulocyte macrophage colony-stimulating factor (GM-CSF), which may promote an immune mediated antitumor response. Areas covered: The US Food and Drug Administration approved Talimogene laherparepvec in late 2015 following the completion of phase I, II and III trials that demonstrated safety and efficacy. Current NCCN practice guidelines have added Talimogene laherparepvec as a primary treatment for stage IIIB/C and stage IVM1a melanoma patients with evidence of good durable response rates, and this article sets out to review the use and safety and efficacy of T-VEC Expert opinion: Treatment options for locally advanced and metastatic melanoma are expanding with new developments in immunotherapy and immune checkpoint inhibitors. The ideal treatment of metastatic melanoma continues to be multimodal, combining systemic treatments, intralesional and regional therapies, surgery and radiotherapy to achieve optimal outcomes. Use of talimogene laherparepvec as intrelsional therapy has demonstrated promising effects in select patients with advanced melanoma. Future directions for Talimogene laherparepvec include combination therapies with other systemic immunotherapies such as anti-CTLA-4 antibody and anti-PD-1 drugs.

Talimogene laherparepvec: overview, combination therapy and current practices

Talimogene laherparepvec (T-VEC, Imlygic®, Amgen, CA, USA) is an oncolytic herpes simplex type 1 virus used as intralesional therapy for unresectable metastatic melanoma in a cutaneous, subcutaneous or nodal location. Talimogene laherparepvec selectively replicates within and lyses tumor cells while producing granulocyte macrophage colony-stimulating factor, which may promote an immune mediated antitumor response. The US FDA approved T-VEC in late 2015 following Phase I-III trials that demonstrated safety and efficacy. Future directions for T-VEC include combination therapies with other systemic immunotherapies such as anti-CTLA-4 antibody and anti-PD-1 drugs. Current National Comprehensive Cancer Network (NCCN) practice guidelines have added T-VEC as a primary treatment for stage IIIB/C and stage IVM1a melanoma patients.

Combination Approaches with Immune-Checkpoint Blockade in Cancer Therapy

In healthy individuals, immune-checkpoint molecules prevent autoimmune responses and limit immune cell-mediated tissue damage. Tumors frequently exploit these molecules to evade eradication by the immune system. Over the past years, immune-checkpoint blockade of cytotoxic T lymphocyte antigen-4 and programed death-1 emerged as promising strategies to activate antitumor cytotoxic T cell responses. Although complete regression and long-term survival is achieved in some patients, not all patients respond. This review describes promising, novel combination approaches involving immune-checkpoint blockade in the context of the cancer-immunity cycle, aimed at increasing response rates to the single treatments. Specifically, we discuss combinations that promote antigen release and presentation, that further amplify T cell activation, that inhibit trafficking of regulatory T cells or MSDCs, that stimulate intratumoral T cell infiltration, that increase cancer recognition by T cells, and that stimulate tumor killing.

Therapeutic Cancer Vaccines

Cancer is one of the major leading death causes of diseases. Prevention and treatment of cancer is an important way to decrease the incidence of tumorigenesis and prolong patients' lives. Subversive achievements on cancer immunotherapy have recently been paid much attention after many failures in basic and clinical researches. Based on deep analysis of genomics and proteomics of tumor antigens, a variety of cancer vaccines targeting tumor antigens have been tested in preclinical and human clinical trials. Many therapeutic cancer vaccines alone or combination with other conventional treatments for cancer obtained spectacular efficacy, indicating the tremendously potential application in clinic. With the illustration of underlying mechanisms of cancer immune regulation, valid, controllable, and persistent cancer vaccines will play important roles in cancer treatment, survival extension and relapse and cancer prevention. This chapter mainly summarizes the recent progresses and developments on cancer vaccine research and clinical application, thus exploring the existing obstacles in cancer vaccine research and promoting the efficacy of cancer vaccine.

Oncolytic virotherapy for urological cancers

Oncolytic virotherapy is a cancer treatment in which replication-competent viruses are used that specifically infect, replicate in and lyse malignant tumour cells, while minimizing harm to normal cells. Anecdotal evidence of the effectiveness of this strategy has existed since the late nineteenth century, but advances and innovations in biotechnological methods in the 1980s and 1990s led to a renewed interest in this type of therapy. Multiple clinical trials investigating the use of agents constructed from a wide range of viruses have since been performed, and several of these enrolled patients with urological malignancies. Data from these clinical trials and from preclinical studies revealed a number of challenges to the effectiveness of oncolytic virotherapy that have prompted the development of further sophisticated strategies. Urological cancers have a range of distinctive features, such as specific genetic mutations and cell surface markers, which enable improving both effectiveness and safety of oncolytic virus treatments. The strategies employed in creating advanced oncolytic agents include alteration of the virus tropism, regulating transcription and translation of viral genes, combination with chemotherapy, radiotherapy or gene therapy, arming viruses with factors that stimulate the immune response against tumour cells and delivery technologies to ensure that the viral agent reaches its target tissue.

Oncolytic vaccine virus harbouring the IL-24 gene suppresses the growth of lung cancer by inducing apoptosis

Lung cancer has an especially high incidence rate worldwide, and its resistance to cell death and chemotherapeutic drugs increases its intractability. The vaccinia virus has been shown to destroy neoplasm within a short time and disseminate rapidly and extensively as an enveloped virion throughout the circulatory system, and this virus has also demonstrated a strong ability to overexpress exogenous genes. Interleukin-24 (IL-24/mda-7) is an important cytokine that belongs to the activating caspase family and facilitates the inhibition of STAT3 when a cell enters the apoptosis pathway. In this study, we constructed a cancer-targeted vaccinia virus carrying the IL-24 gene knocked in the region of the viral thymidine kinase (TK) gene (VV-IL-24). Our results showed that VV-IL-24 efficiently infected and destroyed lung cancer cells via caspase-dependent apoptosis and decreased the expression of STAT3. In vivo, VV-IL-24 expressed IL-24 at a high level in the transplanted tumour, reduced STAT3 activity, and eventually led to apoptosis. In conclusion, we demonstrated that vv-IL-24 has the potential for use as a new human lung cancer treatment.

Cancer immunotherapy: the beginning of the end of cancer?

These are exciting times for cancer immunotherapy. After many years of disappointing results, the tide has finally changed and immunotherapy has become a clinically validated treatment for many cancers. Immunotherapeutic strategies include cancer vaccines, oncolytic viruses, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate cells or block the so-called immune checkpoint pathways. The recent success of several immunotherapeutic regimes, such as monoclonal antibody blocking of cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD1), has boosted the development of this treatment modality, with the consequence that new therapeutic targets and schemes which combine various immunological agents are now being described at a breathtaking pace. In this review, we outline some of the main strategies in cancer immunotherapy (cancer vaccines, adoptive cellular immunotherapy, immune checkpoint blockade, and oncolytic viruses) and discuss the progress in the synergistic design of immune-targeting combination therapies.

Trial Watch-Oncolytic viruses and cancer therapy

Oncolytic virotherapy relies on the administration of non-pathogenic viral strains that selectively infect and kill malignant cells while favoring the elicitation of a therapeutically relevant tumor-targeting immune response. During the past few years, great efforts have been dedicated to the development of oncolytic viruses with improved specificity and potency. Such an intense wave of investigation has culminated this year in the regulatory approval by the US Food and Drug Administration (FDA) of a genetically engineered oncolytic viral strain for use in melanoma patients. Here, we summarize recent preclinical and clinical advances in oncolytic virotherapy.

Cancer immunotherapy via combining oncolytic virotherapy with chemotherapy: recent advances

Oncolytic viruses are multifunctional anticancer agents with huge clinical potential, and have recently passed the randomized Phase III clinical trial hurdle. Both wild-type and engineered viruses have been selected for targeting of specific cancers, to elicit cytotoxicity, and also to generate antitumor immunity. Single-agent oncolytic virotherapy treatments have resulted in modest effects in the clinic. There is increasing interest in their combination with cytotoxic agents, radiotherapy and immune-checkpoint inhibitors. Similarly to oncolytic viruses, the benefits of chemotherapeutic agents may be that they induce systemic antitumor immunity through the induction of immunogenic cell death of cancer cells. Combining these two treatment modalities has to date resulted in significant potential in vitro and in vivo synergies through various mechanisms without any apparent additional toxicities. Chemotherapy has been and will continue to be integral to the management of advanced cancers. This review therefore focuses on the potential for a number of common cytotoxic agents to be combined with clinically relevant oncolytic viruses. In many cases, this combined approach has already advanced to the clinical trial arena.

Oncolytic virotherapy using herpes simplex virus: how far have we come?

Oncolytic virotherapy exploits the properties of human viruses to naturally cytolysis of cancer cells. The human pathogen herpes simplex virus (HSV) has proven particularly amenable for use in oncolytic virotherapy. The relative safety of HSV coupled with extensive knowledge on how HSV interacts with the host has provided a platform for manipulating HSV to enhance the targeting and killing of human cancer cells. This has culminated in the approval of talimogene laherparepvec for the treatment of melanoma. This review focuses on the development of HSV as an oncolytic virus and where the field is likely to head in the future.

Oncolytic Viruses: Exploiting Cancer's Deal with the Devil

Tumor cells harbor tens to thousands of genetic and epigenetic alterations that disrupt cellular pathways, providing them with growth and survival advantages. However, these benefits come at a cost, with uncontrolled cell growth, defective apoptosis, sustained pathological angiogenesis, immune evasion, and a metastatic phenotype occurring at the expense of the antiviral response of the individual tumor cell. Oncolytic virotherapy is an emerging therapeutic strategy that uses replication-competent viruses to selectivity kill cancer cells by exploiting their impaired antiviral response. In this review, we outline our understanding of the alterations in signaling pathways that simultaneously contribute to the malignant phenotype and virus-mediated killing of cancer cells.

Cancer immunotherapy: Strategies for personalization and combinatorial approaches

The results of recent clinical trials using novel immunotherapy strategies such as immune checkpoint blockade and adoptive T-cell therapy approaches including CAR T-cell therapy have clearly established immunotherapy as an important modality for the treatment of cancer besides the traditional approaches of surgery, radiotherapy, and chemotherapy or targeted therapy. However, to date immunotherapy has been shown to induce durable clinical benefit in only a fraction of the patients. The use of combination strategies is likely to increase the number of patients that might benefit from immunotherapy. Indeed, over the last decade, the characterization of multiple immune resistance mechanisms used by the tumor to evade the immune system and the development of agents that target those mechanisms has generated a lot of enthusiasm for cancer immunotherapy. But a critical issue is to determine how best to combine such agents. This review will focus on novel immunotherapy agents currently in development and discuss strategies to develop and personalize combination cancer immunotherapy strategies.

The Rapid Emergence of Novel Therapeutics in Advanced Malignant Melanoma

For decades, no cancer therapy had been shown to improve average survival in metastatic melanoma. Two critical events have occurred, the discovery of melanoma driver mutation subsets and the discovery of immune checkpoint inhibitors, which have allowed for the development of modern, effective therapies. These findings have facilitated a rapid emergence of novel therapeutics for the disease with multiple FDA approvals in the last several years. The drugs vemurafenib, trametinib, and dabrafenib, which inhibit the commonly mutated BRAF pathway, have been approved based on improvements in survival outcomes. Agents that block immune checkpoints on lymphocytes allowing for immune cell activity against melanoma have also been approved based on improved survival outcomes such as ipilimumab and nivolumab. Pembrolizumab, another immune checkpoint inhibitor, has also been approved based on the response rate and duration of response in a phase 1 trial. Further agents and combinations of approved agents are positioned to possibly further increase this tally of approved drugs. This review will discuss recently approved novel agents and select drugs in development in advanced melanoma.