PHOCUS: A Phase 3, Randomized, Open-Label Study of Sequential Treatment with Pexa-Vec (JX-594) and Sorafenib in Patients with Advanced Hepatocellular Carcinoma.

Introduction: Intratumoral administration of pexa-vec (pexastimogene devacirepvec), an oncolytic and immunotherapeutic vaccinia virus, given to patients with hepatocellular carcinoma (HCC), is associated with both local and distant tumor responses. We hypothesized subsequent treatment with sorafenib could demonstrate superior efficacy. Methods: This random phase III open-label study evaluated the sequential treatment with pexa-vec followed by sorafenib compared to sorafenib in patients with advanced HCC and no prior systemic treatment. The primary endpoint is overall survival (OS). Key secondary endpoints included time to progression (TTP), progression-free survival, overall response rate (ORR), and disease control rate (DCR). Safety was assessed in all patients who received ≥1 dose of study treatment. Results: The study was conducted at 142 sites in 16 countries. From December 30, 2015, to the interim analysis on August 2, 2019, 459 patients were randomly assigned (pexa-vec plus sorafenib: 234, sorafenib: 225). At the interim analysis, the median OS was 12.7 months (95% CI: 9.89, 14.95) in the pexa-vec plus sorafenib arm and 14.0 months (95% CI: 11.01, 18.00) in the sorafenib arm. This led to the early termination of the study. The median TTP was 2.0 months (95% CI: 1.77, 2.96) and 4.2 months (95% CI: 2.92, 4.63); ORR was 19.2% (45 patients) and 20.9% (47 patients); and DCR was 50.0% (117 patients) and 57.3% (129 patients) in the pexa-vec plus sorafenib and sorafenib arms, respectively. Serious adverse events were reported in 117 (53.7%) patients in the pexa-vec plus sorafenib and 77 (35.5%) patients in the sorafenib arm. Liver failure was the most frequently reported in both groups. Conclusion: Sequential pexa-vec plus sorafenib treatment did not demonstrate increased clinical benefit in advanced HCC and fared worse compared to sorafenib alone. The advent of the added value of checkpoint inhibitors should direct any further development of oncolytic virus therapy strategies.

Intravenous Oncolytic Vaccinia Virus Therapy Results in a Differential Immune Response between Cancer Patients.

Pexa-Vec is an engineered Wyeth-strain vaccinia oncolytic virus (OV), which has been tested extensively in clinical trials, demonstrating enhanced cytotoxic T cell infiltration into tumours following treatment. Favourable immune consequences to Pexa-Vec include the induction of an interferon (IFN) response, followed by inflammatory cytokine/chemokine secretion. This promotes tumour immune infiltration, innate and adaptive immune cell activation and T cell priming, culminating in targeted tumour cell killing, i.e., an immunologically 'cold' tumour microenvironment is transformed into a 'hot' tumour. However, as with all immunotherapies, not all patients respond in a uniformly favourable manner. Our study herein, shows a differential immune response by patients to intravenous Pexa-Vec therapy, whereby some patients responded to the virus in a typical and expected manner, demonstrating a significant IFN induction and subsequent peripheral immune activation. However, other patients experienced a markedly subdued immune response and appeared to exhibit an exhausted phenotype at baseline, characterised by higher baseline immune checkpoint expression and regulatory T cell (Treg) levels. This differential baseline immunological profile accurately predicted the subsequent response to Pexa-Vec and may, therefore, enable the development of predictive biomarkers for Pexa-Vec and OV therapies more widely. If confirmed in larger clinical trials, these immunological biomarkers may enable a personalised approach, whereby patients with an exhausted baseline immune profile are treated with immune checkpoint blockade, with the aim of reversing immune exhaustion, prior to or alongside OV therapy.

Neoadjuvant Intravenous Oncolytic Vaccinia Virus Therapy Promotes Anticancer Immunity in Patients.

Improving the chances of curing patients with cancer who have had surgery to remove metastatic sites of disease is a priority area for cancer research. Pexa-Vec (Pexastimogene Devacirepvec; JX-594, TG6006) is a principally immunotherapeutic oncolytic virus that has reached late-phase clinical trials. We report the results of a single-center, nonrandomized biological end point study (trial registration: EudraCT number 2012-000704-15), which builds on the success of the presurgical intravenous delivery of oncolytic viruses to tumors. Nine patients with either colorectal cancer liver metastases or metastatic melanoma were treated with a single intravenous infusion of Pexa-Vec ahead of planned surgical resection of the metastases. Grade 3 and 4 Pexa-Vec-associated side effects were lymphopaenia and neutropaenia. Pexa-Vec was peripherally carried in plasma and was not associated with peripheral blood mononuclear cells. Upon surgical resection, Pexa-Vec was found in the majority of analyzed tumors. Pexa-Vec therapy associated with IFNα secretion, chemokine induction, and resulted in transient innate and long-lived adaptive anticancer immunity. In the 2 patients with significant and complete tumor necrosis, a reduction in the peripheral T-cell receptor diversity was observed at the time of surgery. These results support the development of presurgical oncolytic vaccinia virus-based therapies to stimulate anticancer immunity and increase the chances to cure patients with cancer.

Vaccinia Virus Shuffling: deVV5, a Novel Chimeric Poxvirus with Improved Oncolytic Potency.

Oncolytic virus (OV) therapy has emerged as a promising approach for cancer treatment with the potential to be less toxic and more efficient than classic cancer therapies. Various types of OVs in clinical development, including Vaccinia virus (VACV)-derived OVs, have shown good safety profiles, but limited therapeutic efficacy as monotherapy in some cancer models. Many different methods have been employed to improve the oncolytic potency of OVs. In this study, we used a directed evolution process, pooling different strains of VACV, including Copenhagen, Western Reserve and Wyeth strains and the attenuated modified vaccinia virus Ankara (MVA), to generate a new recombinant poxvirus with increased oncolytic properties. Through selective pressure, a chimeric VACV, deVV5, with increased cancer cell killing capacity and tumor selectivity in vitro was derived. The chimeric viral genome contains sequences of all parental strains. To further improve the tumor selectivity and anti-tumor activity of deVV5, we generated a thymidine kinase (TK)-deleted chimeric virus armed with the suicide gene FCU1. This TK-deleted virus, deVV5-fcu1 replicated efficiently in human tumor cells, and was notably attenuated in normal primary cells. These studies demonstrate the potential of directed evolution as an efficient way to generate recombinant poxviruses with increased oncolytic potency, and with high therapeutic index to improve cancer therapy.

TG1042 (Adenovirus-interferon-γ) in primary cutaneous B-cell lymphomas: a phase II clinical trial.

RATIONAL: While a variety of registered therapies exist for Cutaneous T Cell Lymphoma, no such therapy is available for Cutaneous B Cell Therapy. In this context we performed a phase II, open label, multicenter, non-comparative study to evaluate the efficacy and safety of repeated intra-lesional administrations of TG1042 (adenovirus-interferon-γ) in patients with relapsing primary cutaneous B-cell lymphomas (CBCL). METHOD: Thirteen patients have been enrolled and received intralesional injections of TG1042 containing 5×10(10) viral particles into up to six lesions simultaneously. Injections were performed on days 1, 8 and 15 of each of four consecutive 28 day cycles. RESULTS: Eleven (85%) out of 13 enrolled patients showed an objective response after injections of TG1042. Seven patients (54%) exhibited complete and four (31%) displayed partial response. The median time to disease progression in the study population was 23.5 months (range 6.25 to 26+). Most commonly observed adverse events were minor to moderate flu-like symptoms, fatigue and injection site reactions. CONCLUSIONS: Our study showed that treatment with TG1042 was associated with a clinical benefit in the majority of the patients with relapsing CBCL, including tumor regression, a clinically meaningful duration of response and a good treatment tolerance. TRIAL REGISTRATION: www.clinicaltrials.govNCT00394693.

Phase II clinical trial of intratumoral application of TG1042 (adenovirus-interferon-gamma) in patients with advanced cutaneous T-cell lymphomas and multilesional cutaneous B-cell lymphomas.

Cutaneous lymphomas (CLs) are a heterogeneous group of lymphoproliferative disorders that are manageable by immunotherapy. Twenty-one patients were enrolled in a prospective open-label, dose-escalation multicenter study evaluating the effects of repeated TG1042 [adenovirus-interferon (IFN)-gamma] intralesional injections in patients with primary CLs, of which 18 were of T-cell and 3 of B-cell type. Repeated intralesional therapy using TG1042 consistently results in local tumor regressions in about half of treated patients and one-third of patients also in regressions in noninjected distant lesions, likely reflecting the systemic immune activation after intralesional therapy. Treatment was well tolerated with few adverse events including injection site reactions, chills, lymphopenia, and fever. Immune monitoring in the peripheral blood demonstrated systemic immune activation and the induction of antibodies against tumor antigens in some patients without clear association with clinical responses. CLs, in particular B-cell lymphomas with high objective response rates, seem to be excellent targets for this type of immunotherapy.

Targeted chemotherapy for head and neck cancer with a chimeric oncolytic adenovirus coding for bifunctional suicide protein FCU1.

PURPOSE: Transfer of prodrug activation systems into tumors by using replication-deficient viruses has been suggested to be an effective method for achieving high local and low systemic anticancer drug concentrations. However, most current suicide gene therapy strategies are still hindered by poor efficiency of in vivo gene transfer, inefficient tumor penetration, limited bystander cell killing effect, and need of large prodrug doses. We hypothesized that local amplification provided by a replication competent platform would help overcome these limitations. EXPERIMENTAL DESIGN: We generated a transductionally and transcriptionally targeted oncolytic adenovirus Ad5/3-Delta24FCU1 expressing the fusion suicide gene FCU1. FCU1 encodes a bifunctional fusion protein that efficiently catalyzes the direct conversion of 5-FC, a relatively nontoxic antifungal agent, into the toxic metabolites 5-fluorouracil and 5-fluorouridine monophosphate, bypassing the natural resistance of certain human tumor cells to 5-fluorouracil. RESULTS: We examined the efficacy of Ad5/3-Delta24FCU1 and the replication-defective control Ad5/3-FCU1 with and without 5-FC. FCU1 expression was confirmed by Western blot, whereas enzymatic conversion levels in vitro and in vivo were determined by high-performance liquid chromatography separation. Significant antitumor effect was observed in vitro and in vivo in a murine model of head and neck squamous cell carcinoma. Although we observed a decrease in viral DNA copy number in vitro and in tumors treated with Ad5/3-Delta24FCU1 and 5-FC, suggesting an effect on virus replication, the highest antitumor effect was observed for this combination. CONCLUSIONS: It seems feasible and efficacious to combine adenovirus replication to the FCU1 prodrug activation system.

Cellular localization and activity of Ad-delivered GFP-CFTR in airway epithelial and tracheal cells.

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and the cellular trafficking of the CFTR protein is an essential factor that determines its function in cells. The aim of our study was to develop an Ad vector expressing a biologically active green fluorescent protein (GFP)-CFTR chimera that can be tracked by both its localization and chloride channel function. No study thus far has demonstrated a GFP-CFTR construct that displayed both of these functions in the airway epithelia. Tracheal glandular cells, MM39 (CFTRwt) and CF-KM4 (CFTRDeltaF508), as well as human airway epithelial cells from a patient with cystic fibrosis (CF-HAE) and from a healthy donor (HAE) were used for the functional analysis of our Ad vectors, Ad5/GFP-CFTRwt and Ad5/GFP-CFTRDeltaF508. The GFP-CFTRwt protein expressed was efficiently addressed to the plasma membrane of tracheal cells and to the apical surface of polarized CF-HAE cells, while GFP-CFTRDeltaF508 mutant was sequestered intracellularly. The functionality of the GFP-CFTRwt protein was demonstrated by its capacity to correct the chloride channel activity both in CF-KM4 and CF-HAE cells after Ad transduction. A correlation between the proportion of Ad5-transduced CF-KM4 cells and correction of CFTR function showed that 55 to 70% transduction resulted in 70% correction of the Cl- channel function. In reconstituted CF-HAE, GFP-CFTRwt appeared as active as the nontagged CFTRwt protein in correcting the transepithelial Cl- transport. We show for the first time a GFP-CFTR chimera that localized to the apical surface of human airway epithelia and restored epithelial chloride transport to similar levels as nontagged CFTR.

Identification of the glycosylation site of the adenovirus type 5 fiber protein.

The fiber protein purified from the pool of nonincorporated viral protein after infection of cells with adenovirus type 5 exists as two forms separable by reverse-phase HPLC. As determined by mass spectrometry, this heterogeneity results from a difference in one O-linked N-acetylglucosamine (GlcNac). A western blot analysis using a monoclonal antibody directed against the GlcNac motif showed that only one of the two forms reacted with the antibody, suggesting that one form carries a single GlcNac and the other form has none. The ratio of glycosylated to nonglycosylated forms of fiber, which is about 1, is conserved in assembled viruses. After digestion of glycosylated fiber with endoproteinase GluC, isolation of the glycosylated peptide by reverse-phase HPLC, and chemical derivatization using dimethylamine, the site of glycosylation was located in the fiber shaft at serine 109 by mass spectrometry. Elimination of glycosylation by site-directed mutagenesis of fiber should help to understand the function of this postranslational modification.

Good manufacturing practice production of adenoviral vectors for clinical trials.

The increasing importance of recombinant adenoviral vectors for gene therapy, cancer therapy, and the development of prophylactic and therapeutic vaccines has led to worldwide efforts toward scalable process development suitable for commercial manufacturing of replication-deficient adenoviral vectors. This review focuses on the manufacturing of adenovirus for clinical trials in the context of good manufacturing practice conditions and regulations.

Transductional targeting with recombinant adenovirus vectors.

Replication-deficient adenoviruses are considered as gene delivery vectors for the genetic treatment of a variety of diseases. The ability of such vectors to mediate efficient expression of therapeutic genes in a broad spectrum of dividing and non-dividing cell types constitutes an advantage over alternative gene transfer vectors. However, this broad tissue tropism may also turn disadvantageous when genes encoding potentially harmful proteins (e.g. cytokines, toxic proteins) are expressed in surrounding normal tissues. Therefore, specific restrictions of the viral tropism would represent a significant technological advance towards safer and more efficient gene delivery vectors, in particular for cancer gene therapy applications. In this review, we summarize various strategies used to selectively modify the natural tropism of recombinant adenoviruses. The advantages, limitations and potential impact on gene therapy operations of such modified vectors are discussed.