Biosafety and biohazard considerations of HSV-1-based oncolytic viral immunotherapy

Oncolytic viral immunotherapies are agents which can directly kill tumor cells and activate an immune response. Oncolytic viruses (OVs) range from native/unmodified viruses to genetically modified, attenuated viruses with the capacity to preferentially replicate in and kill tumors, leaving normal tissue unharmed. Talimogene laherparepvec (T-VEC) is the only OV approved for patient use in the United States; however, during the last 20 years, there have been a substantial number of clinical trials using OV immunotherapies across a broad range of cancers. Like T-VEC, many OV immunotherapies in clinical development are based on the herpes simplex virus type 1 (HSV-1), with genetic modifications for tumor selectivity, safety, and immunogenicity. Despite these modifications, HSV-1 OV immunotherapies are often treated with the same biosafety guidelines as the wild-type virus, potentially leading to reduced patient access and logistical hurdles for treatment centers, including community treatment centers and small group or private practices, and healthcare workers. Despite the lack of real-world evidence documenting possible transmission to close contacts, and in the setting of shedding and biodistribution analyses for T-VEC demonstrating limited infectivity and low risk of spread to healthcare workers, barriers to treatment with OV immunotherapies remain. With comprehensive information and educational programs, our hope is that updated biosafety guidance on OV immunotherapies will reduce logistical hurdles to ensure that patients have access to these innovative and potentially life-saving medicines across treatment settings. This work reviews a comprehensive collection of data in conjunction with the opinions of the authors based on their clinical experience to provide the suggested framework and key considerations for implementing biosafety protocols for OV immunotherapies, namely T-VEC, the only approved agent to date.

[Stapled anoplin peptide combined with photothermal therapy enhances oncolytic immunotherapy of triple-negative breast cancer]

This study constructed a nano-drug delivery system, A3@GMH, by co-delivering the stapled anoplin peptide(Ano-3, A3) with the light-harvesting material graphene oxide(GO), and evaluated its oncolytic immunotherapy effect on triple-negative breast cancer(TNBC). A3@GMH was prepared using an emulsion template method and its physicochemical properties were characterized. The in vivo and in vitro photothermal conversion abilities of A3@GMH were investigated using an infrared thermal imager. The oncoly-tic activity of A3@GMH against TNBC 4T1 cells was evaluated through cell counting kit-8(CCK-8), lactate dehydrogenase(LDH) release, live/dead cell staining, and super-resolution microscopy. The targeting properties of A3@GMH on 4T1 cells were assessed using a high-content imaging system and flow cytometry. In vitro and in vivo studies were conducted to investigate the antitumor mechanism of A3@GMH in combination with photothermal therapy(PTT) through inducing immunogenic cell death(ICD) in 4T1 cells. The results showed that the prepared A3@GMH exhibited distinct mesoporous and coated structures with an average particle size of(308.9±7.5) nm and a surface potential of(-6.79±0.58) mV. The encapsulation efficiency and drug loading of A3 were 23.9%±0.6% and 20.5%±0.5%, respectively. A3@GMH demonstrated excellent photothermal conversion ability and biological safety. A3@GMH actively mediated oncolytic features such as 4T1 cell lysis and LDH release, as well as ICD effects, and showed enhanced in vitro antitumor activity when combined with PTT. In vivo, A3@GMH efficiently induced ICD effects with two rounds of PTT, activated the host's antitumor immune response, and effectively suppressed tumor growth in 4T1 tumor-bearing mice, achieving an 88.9% tumor inhibition rate with no apparent toxic side effects. This study suggests that the combination of stapled anoplin peptide and PTT significantly enhances the oncolytic immunotherapy for TNBC and provides a basis for the innovative application of anti-tumor peptides derived from TCM in TNBC treatment.

Interventional Oncolytic Immunotherapy with LTX-315 for Residual Tumor after Incomplete Radiofrequency Ablation of Liver Cancer

Objective: To investigate the feasibility of interventional oncolytic immunotherapy with LTX-315 for residual tumors after incomplete radiofrequency ablation (iRFA) of VX2 liver tumors in a rabbit model. Methods: For in vitro experiments, VX2 tumor cells were treated with: (1) phosphate buffered saline, (2) radiofrequency hyperthermia (RFH), (3) LTX-315, and (4) RFH plus LTX-315. The residual tumors after iRFA of VX2 liver tumors were treated with: (1) phosphate buffered saline served as control, (2) 2 mg LTX-315, and (3) 4 mg LTX-315. MTS assay, fluorescence microscopy, and flow cytometry were used to compare cell viabilities and apoptosis among different groups. Ultrasound imaging was used to follow up the tumor growth, which were correlated with the optical imaging and subsequent histology. Results: For in vitro experiments, compared with the other three groups, MTS assay demonstrated the lowest cell viability, fluorescence microscopy showed the least survival cells, and apoptosis analysis revealed the highest percentage of apoptosis cells in the combination treatment groups (p < 0.001). For in vivo experiments, ultrasound imaging showed the smallest tumor volume in the group with 4 mg LTX-315 therapy compared with the other two groups (p < 0.001). The optical imaging and histopathological analysis showed complete necrosis of the tumors in the group with 4 mg LTX-315 therapy. A significant increase of CD8+ T cells and HSP70 and a significant decrease of Tregs were observed in residual tumors in the group with 2 mg LTX-315 therapy compared with the control group (p < 0.001). Conclusion: Interventional oncolytic immunotherapy with LTX-315 for residual tumors after iRFA of liver cancer is feasible, which may open up new avenues to prevent residual tumors after RFA of intermediate-to-large liver cancers.

The employment of vaccinia virus for colorectal cancer treatment: A review of preclinical and clinical studies

Colorectal cancer (CRC) is one of the leading malignancies that causes death worldwide. Cancer vaccines and oncolytic immunotherapy bring new hope for patients with advanced CRC. The capability of vaccinia virus (VV) in carrying foreign genes as antigens or immunostimulatory factors has been demonstrated in animal models. VV of Wyeth, Western Reserve, Lister, Tian Tan, and Copenhagen strains have been engineered for the induction of antitumor response in multiple cancers. This paper summarized the preclinical and clinical application and development of VV serving as cancer vaccines and oncolytic vectors in CRC treatment. Additionally, the remaining challenges and future direction are also discussed.

Polymer chimera of stapled oncolytic peptide coupled with anti-PD-L1 peptide boosts immunotherapy of colorectal cancer

Rationale: Scarce tumor mutation burden and neoantigens create tremendous obstacles for an effective immunotherapy of colorectal cancer (CRC). Oncolytic peptides rise as a promising therapeutic approach that boosts tumor-specific immune responses by inducing antigenic substances. However, the clinical application of oncolytic peptides has been hindered because of structural instability, proteolytic degradation, and undesired toxicity when administered systemically. Methods: Based on wasp venom peptide, an optimized stapled oncolytic peptide MP9 was developed with rigid α-helix, protease-resistance, and CRC cell cytotoxicity. By incorporating four functional motifs that include D-peptidomimetic inhibitor of PD-L1, matrix metalloproteinase-2 (MMP-2) cleavable spacer, and MP9 with 4-arm PEG, a novel peptide-polymer conjugate (PEG-MP9-aPDL1) was obtained and identified as the most promising systemic delivery vehicle with PD-L1 targeting specificity and favorable pharmacokinetic properties. Results: We demonstrated that PEG-MP9-aPDL1-driven oncolysis induces a panel of immunogenic cell death (ICD)-relevant damage-associated molecular patterns (DAMPs) both in vitro and in vivo, which are key elements for immunotherapy with PD-L1 inhibitor. Further, PEG-MP9-aPDL1 exhibited prominent immunotherapeutic efficacy in a CRC mouse model characterized by tumor infiltration of CD8+ T cells and induction of cytotoxic lymphocytes (CTLs) in the spleens. Conclusion: Our findings suggest that PEG-MP9-aPDL1 is an all-in-one platform for oncolytic immunotherapy and immune checkpoint blockade (ICB).

Autophagy in Tumor Immunity and Viral-Based Immunotherapeutic Approaches in Cancer

Autophagy is a fundamental catabolic process essential for the maintenance of cellular and tissue homeostasis, as well as directly contributing to the control of invading pathogens. Unsurprisingly, this process becomes critical in supporting cellular dysregulation that occurs in cancer, particularly the tumor microenvironments and their immune cell infiltration, ultimately playing a role in responses to cancer therapies. Therefore, understanding "cancer autophagy" could help turn this cellular waste-management service into a powerful ally for specific therapeutics. For instance, numerous regulatory mechanisms of the autophagic machinery can contribute to the anti-tumor properties of oncolytic viruses (OVs), which comprise a diverse class of replication-competent viruses with potential as cancer immunotherapeutics. In that context, autophagy can either: promote OV anti-tumor effects by enhancing infectivity and replication, mediating oncolysis, and inducing autophagic and immunogenic cell death; or reduce OV cytotoxicity by providing survival cues to tumor cells. These properties make the catabolic process of autophagy an attractive target for therapeutic combinations looking to enhance the efficacy of OVs. In this article, we review the complicated role of autophagy in cancer initiation and development, its effect on modulating OVs and immunity, and we discuss recent progress and opportunities/challenges in targeting autophagy to enhance oncolytic viral immunotherapy.

Mesenchymal stromal cell delivery of oncolytic immunotherapy improves CAR-T cell antitumor activity

The immunosuppressive tumor microenvironment (TME) is a formidable barrier to the success of adoptive cell therapies for solid tumors. Oncolytic immunotherapy with engineered adenoviruses (OAd) may disrupt the TME by infecting tumor cells, as well as surrounding stroma, to improve the functionality of tumor-directed chimeric antigen receptor (CAR)-T cells, yet efficient delivery of OAds to solid tumors has been challenging. Here we describe how mesenchymal stromal cells (MSCs) can be used to systemically deliver a binary vector containing an OAd together with a helper-dependent Ad (HDAd; combinatorial Ad vector [CAd]) that expresses interleukin-12 (IL-12) and checkpoint PD-L1 (programmed death-ligand 1) blocker. CAd-infected MSCs deliver and produce functional virus to infect and lyse lung tumor cells while stimulating CAR-T cell anti-tumor activity by release of IL-12 and PD-L1 blocker. The combination of this approach with administration of HER.2-specific CAR-T cells eliminates 3D tumor spheroids in vitro and suppresses tumor growth in two orthotopic lung cancer models in vivo. Treatment with CAd MSCs increases the overall numbers of human T cells in vivo compared to CAR-T cell only treatment and enhances their polyfunctional cytokine secretion. These studies combine the predictable targeting of CAR-T cells with the advantages of cancer cell lysis and TME disruption by systemic MSC delivery of oncolytic virotherapy: incorporation of immunostimulation by cytokine and checkpoint inhibitor production through the HDAd further enhances anti-tumor activity.

Expression of Oncolytic Adenovirus-Encoded RNAi Molecules Is Most Effective in a pri-miRNA Precursor Format

Oncolytic adenoviruses are being developed as new anti-cancer agents. Their efficacy can be improved by incorporating RNA interference (RNAi) molecules. RNAi molecules can be expressed in various precursor formats. The aim of this study was to determine the most effective format. To this end, we constructed three Δ24-type oncolytic adenoviruses, with human microRNA-1 (miR-1) expression cassettes in short hairpin RNA (shRNA), precursor microRNA (pre-miRNA), and primary miRNA (pri-miRNA) format, respectively. The viruses were compared for virus replication, mature miR-1 expression, and target gene silencing in cancer cells. Incorporation of the cassettes had only minor effects on virus replication. Mature miR-1 expression from the pri-miRNA format reached on average 100-fold higher levels than from the other two formats. This expression remained stable upon long-term virus propagation. Infection with the pri-miR-1-expressing virus silenced the validated miR-1 targets FOXP1 and MET. Drosha knockout almost completely abrogated mature miR-1 expression, confirming that processing of adenovirus-encoded pri-miR-1 was dependent on the host cell miRNA machinery. Using simple in vitro recombination cloning, a similar virus expressing miR-26b was made and shown to silence the validated miR-26b target PTGS2. We thus provide a platform for construction of oncolytic adenoviruses with high expression of RNAi molecules of choice.

High Oncolytic Activity of a Double-Deleted Vaccinia Virus Copenhagen Strain against Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a cancer of the pleura that lacks efficient treatment. Oncolytic immunotherapy using oncolytic vaccinia virus (VV) may represent an alternative therapeutic approach for the treatment of this malignancy. Here, we studied the oncolytic activity of VV thymidine kinase (TK)-ribonucleotide reductase (RR)-/green fluorescent protein (GFP) against MPM. This virus is a VV from the Copenhagen strain that is deleted of two genes encoding the TK (J2R) and the RR (I4L) and that express the GFP. First, we show in vitro that VVTK-RR-/GFP efficiently infects and kills the twenty-two human MPM cell lines used in this study. We also show that the virus replicates in all eight tested MPM cell lines, however, with approximately a 10-fold difference in the amplification level from one cell line to another. Then, we studied the therapeutic efficiency of VVTK-RR-/GFP in non-obese diabetic (NOD) severe combined immunodeficient (SCID) mice that bear peritoneal human MPM tumors. One intraperitoneal infection of VVTK-RR-/GFP reduces the tumor burden and significantly increases mice survival compared to untreated animals. Thus, VVTK-RR- may be a promising oncolytic virus (OV) for the oncolytic immunotherapy of MPM.

Oncolytic Herpes Simplex Virus Encoding IL12 Controls Triple-Negative Breast Cancer Growth and Metastasis

Triple-negative breast cancer (TNBC) is a difficult-to-treat disease with high rates of local recurrence, distant metastasis, and poor overall survival with existing therapies. Thus, there is an unmet medical need to develop new treatment regimen(s) for TNBC patients. An oncolytic herpes simplex virus encoding a master anti-tumor cytokine, interleukin 12, (designated G47Δ-mIL12) selectively kills cancer cells while inducing anti-tumor immunity. G47Δ-mIL12 efficiently infected and killed murine (4T1 and EMT6) and human (HCC1806 and MDA-MB-468) mammary tumor cells in vitro. In vivo in the 4T1 syngeneic TNBC model, it significantly reduced primary tumor burden and metastasis, both at early and late stages of tumor development. The virus-induced local and abscopal effects were confirmed by significantly increased infiltration of CD45⁺ leukocytes and CD8⁺ T cells, and reduction of granulocytic and monocytic MDSCs in tumors, both treated and untreated contralateral, and in the spleen. Significant trafficking of dendritic cells (DCs) were only observed in spleens of virus-treatment group, indicating that DCs are primed and activated in the tumor-microenvironment following virotherapy, and trafficked to lymphoid organs for activation of immune cells, such as CD8⁺ T cells. DC priming/activation could be associated with virally enhanced expression of several antigen processing/presentation genes in the tumor microenvironment, as confirmed by NanoString gene expression analysis. Besides DC activation/priming, G47Δ-mIL12 treatment led to up-regulation of CD8⁺ T cell activation markers in the tumor microenvironment and inhibition of tumor angiogenesis. The anti-tumor effects of G47Δ-mIL12 treatment were CD8-dependent. These studies illustrate the ability of G47Δ-mIL12 to immunotherapeutically treat TNBC.

Vaccinia-based oncolytic immunotherapy Pexastimogene Devacirepvec in patients with advanced hepatocellular carcinoma after sorafenib failure: a randomized multicenter Phase IIb trial (TRAVERSE)

Pexastimogene devacirepvec (Pexa-Vec) is a vaccinia virus-based oncolytic immunotherapy designed to preferentially replicate in and destroy tumor cells while stimulating anti-tumor immunity by expressing GM-CSF. An earlier randomized Phase IIa trial in predominantly sorafenib-naïve hepatocellular carcinoma (HCC) demonstrated an overall survival (OS) benefit. This randomized, open-label Phase IIb trial investigated whether Pexa-Vec plus Best Supportive Care (BSC) improved OS over BSC alone in HCC patients who failed sorafenib therapy (TRAVERSE).

129 patients were randomly assigned 2:1 to Pexa-Vec plus BSC vs. BSC alone. Pexa-Vec was given as a single intravenous (IV) infusion followed by up to 5 IT injections. The primary endpoint was OS. Secondary endpoints included overall response rate (RR), time to progression (TTP) and safety.

A high drop-out rate in the control arm (63%) confounded assessment of response-based endpoints. Median OS (ITT) for Pexa-Vec plus BSC vs. BSC alone was 4.2 and 4.4 months, respectively (HR, 1.19, 95% CI: 0.78–1.80; p = .428). There was no difference between the two treatment arms in RR or TTP. Pexa-Vec was generally well-tolerated. The most frequent Grade 3 included pyrexia (8%) and hypotension (8%). Induction of immune responses to vaccinia antigens and HCC associated antigens were observed.

Despite a tolerable safety profile and induction of T cell responses, Pexa-Vec did not improve OS as second-line therapy after sorafenib failure. The true potential of oncolytic viruses may lie in the treatment of patients with earlier disease stages which should be addressed in future studies.

ClinicalTrials.gov: NCT01387555

Practical clinical guide on the use of talimogene laherparepvec monotherapy in patients with unresectable melanoma in Europe

Talimogene laherparepvec, a herpes simplex virus type 1-based intralesional oncolytic immunotherapy, is approved in Europe for the treatment of adults with unresectable stage IIIB-IVM1a melanoma, with no bone, brain, lung or other visceral disease. It has direct oncolytic effects in injected lesions, leading to the release of tumour-derived antigens and systemic immune effects mediated by the induction of anti-tumour immunity, which is enhanced by the production of granulocyte macrophage colony-stimulating factor. Responses (which occur in >40% of stage IIIB-IVM1a patients) are often durable (>50% last ≥6 months) and occur in injected and uninjected lesions (in stage IIIB-IVM1c patients, 64%/34% of evaluable injected/uninjected non-visceral lesions, respectively, decreased in size by ≥50%). As with other immunotherapies, responses may be delayed or can arise after pseudoprogression. The pattern of treatment-emergent adverse events is distinct, being mostly grade 1/2, easy to manage, and rarely leading to treatment discontinuation. Systemic therapy represents the backbone of care for many metastatic melanoma patients. Nonetheless, the potential for durable locoregional control with a locally injected agent may make talimogene laherparepvec suitable for selected patients with stage IIIB/C disease, for whom surgery is not possible (e.g. with in-transit metastases, multiple melanoma lesions at different body sites, or those relapsing rapidly after repeated rounds of surgery) and slowly progressing disease. Here, we discuss which patients could be suitable for talimogene laherparepvec monotherapy based on the European indication, review the patterns/timing of response, and discuss the incidence/management of adverse events. Its potential use combined with immune checkpoint inhibitors is also discussed.

A practical guide to the handling and administration of personalized transcriptionally attenuated oncolytic adenoviruses (PTAVs)

The aim of this review is to provide practical information on the handling, storage, and administration procedures for personalized oncolytic adenoviruses (PTAVs), which have recently entered clinical trials. As described herein, personalized oncolytic viruses refer to transcriptionally attenuated (TA) type 5 adenoviruses that are engineered to carry one or more neoantigenic transgenes derived from patient tumors. Vials of personalized viruses should be stored at -60°C without refreezing after thawing to maintain infectivity. To prevent accidental exposure and transmission, full implementation of universal precautions for preparation, administration, and handling is required. Contaminated materials that come into contact with personalized viruses should be properly disposed of in accordance with local institutional procedures. Severely immunocompromised or pregnant healthcare workers should not prepare or administer personalized viruses or directly contact injection sites. Personalized viruses are administered subcutaneously and intratumorally; however, only subcutaneous injection will be considered in this review. The specific storage, handling, administration, and safety requirements for personalized viruses are easily managed in the context of a clinical trial following the directives from the study protocol.

Third-generation oncolytic herpes simplex virus inhibits the growth of liver tumors in mice

Multimodality therapies are used to manage patients with hepatocellular carcinoma (HCC), although advanced HCC is incurable. Oncolytic virus therapy is probably the next major breakthrough in cancer treatment. The third-generation oncolytic herpes simplex virus type 1 (HSV-1) T-01 kills tumor cells without damaging the surrounding normal tissues. Here we investigated the antitumor effects of T-01 on HCC and the host's immune response to HCC cells. The cytopathic activities of T-01 were tested in 14 human and 1 murine hepatoma cell line in vitro. In various mouse xenograft models, HuH-7, KYN-2, PLC/PRF/5 and HepG2 human cells and Hepa1-6 murine cells were used to investigate the in vivo efficacy of T-01. T-01 was cytotoxic to 13 cell lines (in vitro). In mouse xenograft models of subcutaneous, orthotopic and peritoneal tumor metastasis in athymic mice (BALB/c nu/nu), the growth of tumors formed by the human HCC cell lines and hepatoblastoma cell line was inhibited by T-01 compared with that of mock-inoculated tumors. In a bilateral Hepa1-6 subcutaneous tumor model in C57BL/6 mice, the growth of tumors inoculated with T-01 was inhibited, as was the case for contralateral tumors. T-01 also significantly reduced tumor growth. T-01 infection significantly enhanced antitumor efficacy via T cell-mediated immune responses. Results demonstrate that a third-generation oncolytic HSV-1 may serve as a novel treatment for patients with HCC.

Immunotherapeutic Potential of Oncolytic H-1 Parvovirus: Hints of Glioblastoma Microenvironment Conversion towards Immunogenicity

Glioblastoma, one of the most aggressive primary brain tumors, is characterized by highly immunosuppressive microenvironment. This contributes to glioblastoma resistance to standard treatment modalities and allows tumor growth and recurrence. Several immune-targeted approaches have been recently developed and are currently under preclinical and clinical investigation. Oncolytic viruses, including the autonomous protoparvovirus H-1 (H-1PV), show great promise as novel immunotherapeutic tools. In a first phase I/IIa clinical trial (ParvOryx01), H-1PV was safe and well tolerated when locally or systemically administered to recurrent glioblastoma patients. The virus was able to cross the blood-brain (tumor) barrier after intravenous infusion. Importantly, H-1PV treatment of glioblastoma patients was associated with immunogenic changes in the tumor microenvironment. Tumor infiltration with activated cytotoxic T cells, induction of cathepsin B and inducible nitric oxide (NO) synthase (iNOS) expression in tumor-associated microglia/macrophages (TAM), and accumulation of activated TAM in cluster of differentiation (CD) 40 ligand (CD40L)-positive glioblastoma regions was detected. These are the first-in-human observations of H-1PV capacity to switch the immunosuppressed tumor microenvironment towards immunogenicity. Based on this pilot study, we present a tentative model of H-1PV-mediated modulation of glioblastoma microenvironment and propose a combinatorial therapeutic approach taking advantage of H-1PV-induced microglia/macrophage activation for further (pre)clinical testing.

Oncolytic Virotherapy Promotes Intratumoral T Cell Infiltration and Improves Anti-PD-1 Immunotherapy

Here we report a phase 1b clinical trial testing the impact of oncolytic virotherapy with talimogene laherparepvec on cytotoxic T cell infiltration and therapeutic efficacy of the anti-PD-1 antibody pembrolizumab. Twenty-one patients with advanced melanoma were treated with talimogene laherparepvec followed by combination therapy with pembrolizumab. Therapy was generally well tolerated, with fatigue, fevers, and chills as the most common adverse events. No dose-limiting toxicities occurred. Confirmed objective response rate was 62%, with a complete response rate of 33% per immune-related response criteria. Patients who responded to combination therapy had increased CD8⁺ T cells, elevated PD-L1 protein expression, as well as IFN-γ gene expression on several cell subsets in tumors after talimogene laherparepvec treatment. Response to combination therapy did not appear to be associated with baseline CD8⁺ T cell infiltration or baseline IFN-γ signature. These findings suggest that oncolytic virotherapy may improve the efficacy of anti-PD-1 therapy by changing the tumor microenvironment. VIDEO ABSTRACT.

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.

Designing and building oncolytic viruses

Oncolytic viruses (OVs) are engineered and/or evolved to propagate selectively in cancerous tissues. They have a dual mechanism of action; direct killing of infected cancer cells cross-primes anticancer immunity to boost the killing of uninfected cancer cells. The goal of the field is to develop OVs that are easily manufactured, efficiently delivered to disseminated sites of cancer growth, undergo rapid intratumoral spread, selectively kill tumor cells, cause no collateral damage and pose no risk of transmission in the population. Here we discuss the many virus engineering strategies that are being pursued to optimize delivery, intratumoral spread and safety of OVs derived from different virus families. With continued progress, OVs have the potential to transform the paradigm of cancer care.

Administration and Handling of Talimogene Laherparepvec: An Intralesional Oncolytic Immunotherapy for Melanoma

PURPOSE/OBJECTIVES

To describe the administration and handling requirements of oncolytic viruses in the context of talimogene laherparepvec (Imlygic™), a first-in-class oncolytic immunotherapy.
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DATA SOURCES

Study procedures employed in clinical trials, in particular the OPTiM study.
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DATA SYNTHESIS

Evaluation of nursing considerations for administration of talimogene laherparepvec.
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CONCLUSIONS

Talimogene laherparepvec is administered through a series of intralesional injections into cutaneous, subcutaneous, or nodal tumors (with ultrasound guidance as needed) during an outpatient clinic visit. A single insertion point is recommended; however, multiple insertion points are acceptable if the tumor radius exceeds the needle's radial reach. Talimogene laherparepvec must be evenly distributed throughout the tumor through each insertion site. Talimogene laherparepvec requires storage at -90°C to -70°C and, once thawed, should be administered immediately or stored in its original vial and carton and protected from light in a refrigerator (2°C to 8°C). 
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IMPLICATIONS FOR NURSING

Because talimogene laherparepvec can be administered in the outpatient setting, nurses will be pivotal for appropriate integration and administration of this unique and effective therapy.

Oncolytic virus therapy: A new era of cancer treatment at dawn

Oncolytic virus therapy is perhaps the next major breakthrough in cancer treatment following the success in immunotherapy using immune checkpoint inhibitors. Oncolytic viruses are defined as genetically engineered or naturally occurring viruses that selectively replicate in and kill cancer cells without harming the normal tissues. T‐Vec (talimogene laherparepvec), a second‐generation oncolytic herpes simplex virus type 1 (HSV‐1) armed with GM‐CSF, was recently approved as the first oncolytic virus drug in the USA and Europe. The phase III trial proved that local intralesional injections with T‐Vec in advanced malignant melanoma patients can not only suppress the growth of injected tumors but also act systemically and prolong overall survival. Other oncolytic viruses that are closing in on drug approval in North America and Europe include vaccinia virus JX‐594 (pexastimogene devacirepvec) for hepatocellular carcinoma, GM‐CSF‐expressing adenovirus CG0070 for bladder cancer, and Reolysin (pelareorep), a wild‐type variant of reovirus, for head and neck cancer. In Japan, a phase II clinical trial of G47∆, a third‐generation oncolytic HSV‐1, is ongoing in glioblastoma patients. G47∆ was recently designated as a “Sakigake” breakthrough therapy drug in Japan. This new system by the Japanese government should provide G47∆ with priority reviews and a fast‐track drug approval by the regulatory authorities. Whereas numerous oncolytic viruses have been subjected to clinical trials, the common feature that is expected to play a major role in prolonging the survival of cancer patients is an induction of specific antitumor immunity in the course of tumor‐specific viral replication. It appears that it will not be long before oncolytic virus therapy becomes a standard therapeutic option for all cancer patients.

Immune based therapy for melanoma

A few years ago therapeutic options in advanced melanoma were very limited and the prognosis was somber. Although recent progresses are far from providing a cure for advanced melanoma, yet these have kindled new hopes and searching for a cure does not seem unreasonable. Seven new medicines have been authorized in various regions of the world in the recent past in the therapy of advanced melanoma, over half of them acting by mechanisms involving the immune system of the host. The anti-CTLA-4 (cytotoxic T lymphocyte associated protein-4) ipilimumab has been followed by anti-PD1 (programmed death1) inhibitors, more effective and safer. Very recently, the first oncolytic immunotherapy, talimogene laherparepvec (T-VEC) has been authorized for placing on the market and a variety of combinations of the new therapies are currently being evaluated or considered. Besides, a plethora of other molecules and approaches, especially monoclonal antibodies, are in the preliminary phases of clinical investigation and are likely to bring new benefits for the treatment of this potentially fatal form of cancer.

The emerging therapeutic potential of the oncolytic immunotherapeutic Pexa-Vec (JX-594)

Oncolytic immunotherapeutics (OIs) are viruses designed to preferentially replicate in and lyse cancer cells, thereby triggering antitumor immunity. Numerous oncolytic platforms are currently in clinical development. Here we review preclinical and clinical experience with Pexa-Vec (pexastimogene devacirepvec, JX-594). Pexa-Vec is derived from a vaccinia vaccine strain that has been engineered to target cancer cells and express the therapeutic transgene granulocyte macrophage colony-stimulating factor (GM-CSF) in order to stimulate antitumor immunity. Key to its ability to target metastatic disease is the evolution of unique vaccinia virus characteristics that allow for effective systemic dissemination. Multiple mechanisms of action (MOA) for Pexa-Vec have been demonstrated in preclinical models and patients: 1) tumor cell infection and lysis, 2) antitumor immune response induction, and 3) tumor vascular disruption. This review will summarize data on the Pexa-Vec MOA as well as provide an overview of the Pexa-Vec clinical development program from multiple Phase I studies, Phase II studies in renal cell cancer and colorectal cancer, through Phase IIb clinical testing in patients with advanced hepatocellular carcinoma (primary liver cancer).