RESUMEN

Coxsackievirus A21 (CVA21) is a naturally occurring RNA virus that, in preclinical studies and clinical trials, has demonstrated promising potential in treating a range of malignancies. Other oncolytic viruses, such as adenovirus, vesicular stomatitis virus, herpesvirus, and vaccinia virus, all can be engineered to carry one or more transgenes for various purposes, including immune modulation, virus attenuation, and induction of apoptosis of tumor cells. However, it remained unknown whether CVA21 can express therapeutic or immunomodulatory payloads due to its small size and high mutation rate. Using reverse genetics techniques, we demonstrated that a transgene encoding a truncated green fluorescent protein (GFP) of up to 141 amino acids (aa) can be successfully carried in the 5' end of the coding region. Furthermore, a chimeric virus carrying an eel fluorescent protein, UnaG (139 aa), was also made and shown to be stable, and it maintained efficient tumor cell-killing activity. Similar to other oncolytic viruses, the likelihood of delivering CVA21 by the intravenous route is low due to issues like blood absorption, neutralizing antibodies, and liver clearance. To address this problem, we designed the CVA21 cDNA under the control of a weak RNA polymerase II promoter, and subsequently, a stable cell pool in 293T cells was made by integrating the resulting CVA21 cDNA into the cell genome. We showed that the cells are viable and able to persistently generate rCVA21 de novo. The carrier cell approach described here may pave the way to designing new cell therapy strategies by arming with oncolytic viruses. IMPORTANCE As a naturally occurring virus, coxsackievirus A21 is a promising oncolytic virotherapy modality. In this study, we first used reverse genetics to determine whether A21 can stably carry transgenes and found that it could express up to 141 amino acids of foreign GFP. The chimeric virus carrying another fluorescent eel protein UnaG (139 amino acids) gene also appeared to be stable over at least 7 passages. Our results provided guidance on how to select and engineer therapeutic payloads for future A21 anticancer research. Second, the challenges of delivering oncolytic viruses by the intravenous route hamper the broader use of oncolytic viruses in the clinic. Here, we used A21 to show that cells could be engineered to stably carry and persistently release the virus by harboring the viral cDNA in the genome. The approach we presented here may pave a new way for oncolytic virus administration using cells as carriers.

Asunto(s)

Enterovirus Humano A , Virus Oncolíticos , Aminoácidos/genética , Línea Celular Tumoral , ADN Complementario , Enterovirus Humano A/genética , Viroterapia Oncolítica/métodos , Virus Oncolíticos/genética , Transgenes

RESUMEN

Oncolytic viruses (OVs) are being developed as a type of immunotherapy and have demonstrated durable tumor responses and clinical efficacy. One such OV, Coxsackievirus A21 (CVA21), exhibited therapeutic efficacy in early phase clinical trials, demonstrating the ability to infect and kill cancer cells and stimulate anti-tumor immune responses. However, one of the major concerns in using this common cold virus as a therapeutic is the potential for innate and adaptive immune responses to mitigate the benefits of viral infection, particularly in individuals that have been exposed to coxsackievirus prior to treatment. In this study, we assess melanoma responses to CVA21 in the absence or presence of prior exposure to the virus. Melanomas were transplanted into naïve or CVA21-immunized C57BL6 mice and the mice were treated with intratumoral (IT) CVA21. We find that prior exposure to CVA21 does not dramatically affect tumor responses, nor does it alter overall survival. Our results suggest that prior exposure to coxsackievirus is not a critical determinant of patient selection for IT CVA21 interventions.

RESUMEN

INTRODUCTION: Melanoma treatments have evolved rapidly in the past decade and have included the use of intratumoral injections of engineered oncolytic viruses. One such oncolytic virus is talimogene laherparepvec (T-VEC), which is the first approved therapy of its kind for use in recurrent, unresectable stage IIIB-IVM1a melanoma. Additional oncolytic viruses and their uses in combination with other interventions are currently under investigation. AREAS COVERED: Oncolytic viruses are being evaluated as immunotherapies for a variety of advanced malignancies. In this article, we review T-VEC, the only FDA-approved engineered oncolytic virus, in addition to ongoing research regarding other oncolytic viruses for the treatment of advanced melanomas. Finally, we discuss opportunities to improve these therapies through viral, host, and tumor-related modifications. EXPERT OPINION: Engineered and naturally oncolytic viruses have demonstrable local and systemic efficacy as immunotherapies in cancer. T-VEC leads the way with improved survival outcomes for unresectable, stage IIIB-IVM1a melanoma as a monotherapy, and is demonstrating superior results in combination with systemic checkpoint inhibitors. Additional viral vectors show acceptable safety profiles and varying degrees of efficacy in targeting melanoma. The indications for use of oncolytic viruses will expand as their efficacy and appropriate usage is better understood in coming years.

Asunto(s)

Bioingeniería , Inmunoterapia , Melanoma/terapia , Viroterapia Oncolítica , Virus Oncolíticos/fisiología , Animales , Bioingeniería/métodos , Bioingeniería/tendencias , Vectores Genéticos , Humanos , Inmunoterapia/métodos , Inmunoterapia/tendencias , Melanoma/patología , Viroterapia Oncolítica/métodos , Viroterapia Oncolítica/tendencias , Virus Oncolíticos/genética , Recurrencia , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/terapia , Melanoma Cutáneo Maligno

RESUMEN

The clinical management of cancer continues to be dominated by macroscopic surgical resection, radiotherapy, and cytotoxic drugs. The major challenge facing oncology is to achieve more selective, less toxic and effective methods of targeting disseminated tumors, a challenge oncolytic virotherapy may be well-placed to meet. Characterization of coxsackievirus A21 (CVA21) receptor-based mechanism of virus internalization and lysis in the last decade has suggested promise for CVA21 as a virotherapy against malignancies which overexpress those receptors. Preclinical studies have demonstrated proof of principle, and with the results of early clinical trials awaited, CVA21 may be one of the few viruses to demonstrate benefit for patients. This review outlines the potential of CVA21 as an oncolytic agent, describing the therapeutic development of CVA21 in preclinical studies and early stage clinical trials. Preclinical evidence supports the potential use of CVA21 across a range of malignancies. Malignant melanoma is the most intensively studied cancer, and may represent a "test case" for future development of the virus. Although there are theoretical barriers to the clinical utility of oncolytic viruses like CVA21, whether these will block the efficacy of the virus in clinical practice remains to be established, and is a question which can only be answered by appropriate trials. As these data become available, the rapid journey of CVA21 from animal studies to clinical trials may offer a model for the translation of other oncolytic virotherapies from laboratory to clinic.