Abscopal effect when combining oncolytic adenovirus and checkpoint inhibitor in a humanized NOG mouse model of melanoma.

Melanoma, an immunogenic tumor, is the first indication where oncolytic viruses are now becoming part of clinical practice. ONCOS-102, a transgened adenovirus, has shown to act as a primer of relevant tumor targeting immune cells both in preclinical and clinical melanoma studies. Strategies to augment its effectiveness warrant investigation. Combination therapy of ONCOS-102 with the checkpoint inhibitor (CPI) pembrolizumab was evaluated in a quasi-human animal model, the humanized NOG mouse model. A dosing schedule of the combination, beginning the CPI concurrently with the oncolytic viral therapy and continuing the CPI treatment, appeared to induce an abscopal effect in untreated tumor lesions. Concurrent combination therapy with checkpoint inhibitors may improve the induction of antitumor immune responses of ONCOS-102.

Optimization of Early Steps in Oncolytic Adenovirus ONCOS-401 Production in T-175 and HYPERFlasks.

Oncolytic adenoviruses can trigger lysis of tumor cells, induce an antitumor immune response, bypass classical chemotherapeutic resistance strategies of tumors, and provide opportunities for combination strategies. A major challenge is the development of scalable production methods for viral seed stocks and sufficient quantities of clinical grade viruses. Because of promising clinical signals in a compassionate use program (Advanced Therapy Access Program) which supported further development, we chose the oncolytic adenovirus ONCOS-401 as a testbed for a new approach to scale up. We found that the best viral production conditions in both T-175 flasks and HYPERFlasks included A549 cells grown to 220,000 cells/cm² (80% confluency), with ONCOS-401 infection at 30 multiplicity of infection (MOI), and an incubation period of 66 h. The Lysis A harvesting method with benzonase provided the highest viral yield from both T-175 and HYPERFlasks (10,887 ± 100 and 14,559 ± 802 infectious viral particles/cell, respectively). T-175 flasks and HYPERFlasks produced up to 2.1 × 108 ± 0.2 and 1.75 × 108 ± 0.08 infectious particles of ONCOS-401 per cm² of surface area, respectively. Our findings suggest a suitable stepwise process that can be applied to optimizing the initial production of other oncolytic viruses.

Antitumor-specific T-cell responses induced by oncolytic adenovirus ONCOS-102 (AdV5/3-D24-GM-CSF) in peritoneal mesothelioma mouse model.

Oncolytic adenoviral immunotherapy activates the innate immune system with subsequent induction of adaptive tumor-specific immune responses to fight cancer. Hence, oncolytic viruses do not only eradicate cancer cells by direct lysis, but also generate antitumor immune response, allowing for long-lasting cancer control and tumor reduction. Their therapeutic effect can be further enhanced by arming the oncolytic adenovirus with costimulatory transgenes and/or coadministration with other antitumor therapies. ONCOS-102 has already been found to be well tolerated and efficacious against some types of treatment-refractory tumors, including mesothelin-positive ovarian cancer (NCT01598129). It induced local and systemic CD8+ T-cell immunity and upregulated programmed death ligand 1. These results strongly advocate the use of ONCOS-102 in combination with other therapeutic strategies in advanced and refractory tumors, especially those expressing the mesothelin antigen. The in vivo work presented herein describes the ability of the oncolytic adenovirus ONCOS-102 to induce mesothelin-specific T-cells after the administration of the virus in bagg albino (BALB/c) mice with mesothelin-positive tumors. We also demonstrate the effectiveness of the interferon-γ the enzyme-linked immunospot (ELISPOT) assay to detect the induction of T-cells recognizing mesothelin, hexon, and E1A antigens in ONCOS-102-treated mesothelioma-bearing BALB/c mice. Thus, the ELISPOT assay could be useful to monitor the progress of therapy with ONCOS-102.

Pilot Study of ONCOS-102 and Pembrolizumab: Remodeling of the Tumor Microenvironment and Clinical Outcomes in Anti-PD-1-Resistant Advanced Melanoma.

PURPOSE: Intratumoral oncolytic virotherapy may overcome anti-PD(L)-1 resistance by triggering pro-inflammatory remodeling of the tumor microenvironment. This pilot study investigated ONCOS-102 (oncolytic adenovirus expressing GM-CSF) plus anti-programmed cell death protein 1 (PD)-1 therapy in anti-PD-1-resistant melanoma. PATIENTS AND METHODS: Patients with advanced melanoma progressing after prior PD-1 blockade received intratumoral ONCOS-102 either as priming with 3 doses (3 × 1011 viral particles) during Week 1 [Part 1 (sequential treatment)] or as 4-dose priming and 8 booster doses every 3 weeks [Part 2 (combination treatment)]. From Week 3, all patients received pembrolizumab every 3 weeks (≤8 doses). The primary endpoint was safety. Objective response rate (ORR), progression-free survival, and immunologic activation in repeat biopsies were also investigated. RESULTS: In 21 patients (Part 1, n = 9; Part 2, n = 12) ONCOS-102 plus pembrolizumab was well tolerated: most adverse events (AE) were mild/moderate in severity. Pyrexia (43%), chills (43%), and nausea (28%) were the most common ONCOS-102-related AEs. There were no dose-limiting toxicities. ORR was 35% [response evaluation in solid tumors (RECIST) 1.1, irRECIST]. Reduction in size of ≥1 non-injected lesions observed in 53% patients indicated a systemic effect. In injected tumors, persistent immune-related gene expression and T-cell infiltration were associated with clinical benefit. Viral persistence and efficacy in injected and non-injected lesions without additional toxicity supported Part 2 dosing regimen in future studies. CONCLUSIONS: ONCOS-102 plus pembrolizumab was well tolerated and led to objective responses in patients with anti-PD-1-resistant advanced melanoma. ONCOS-102 promoted T-cell infiltration, particularly cytotoxic CD8+ T cells, which persisted at Week 9, driving clinical benefit. Further investigation of ONCOS-102 plus PD-1 blockade is warranted. See related commentary by Levi and Boland, p. 3.

ONCOS-102 plus pemetrexed and platinum chemotherapy in malignant pleural mesothelioma: a randomized phase 2 study investigating clinical outcomes and the tumor microenvironment.

BACKGROUND: ONCOS-102, an oncolytic adenovirus expressing granulocyte-macrophage colony-stimulating factor, can alter the tumor microenvironment to an immunostimulatory state. Combining ONCOS-102 with standard-of-care chemotherapy for malignant pleural mesothelioma (MPM) may improve treatment outcomes. METHODS: In this open-label, randomized study, patients with unresectable MPM received intratumoral ONCOS-102 (3×1011 virus particles on days 1, 4, 8, 36, 78, and 120) and pemetrexed plus cisplatin/carboplatin (from day 22), or pemetrexed plus cisplatin/carboplatin alone. The primary endpoint was safety. Overall survival (OS), progression-free survival, objective response rate, and tumor immunologic activation (baseline and day 36 biopsies) were also assessed. RESULTS: In total, 31 patients (safety lead-in: n=6, randomized: n=25) were enrolled. Anemia (15.0% and 27.3%) and neutropenia (40.0% and 45.5%) were the most frequent grade ≥3 adverse events (AEs) in the ONCOS-102 (n=20) and chemotherapy-alone (n=11) cohorts. No patients discontinued ONCOS-102 due to AEs. No statistically significant difference in efficacy endpoints was observed. There was a numerical improvement in OS (30-month OS rate 34.1% vs 0; median OS 20.3 vs 13.5 months) with ONCOS-102 versus chemotherapy alone in chemotherapy-naïve patients (n=17). By day 36, ONCOS-102 was associated with increased T-cell infiltration and immune-related gene expression that was not observed in the control cohort. Substantial immune activation in the tumor microenvironment was associated with survival at month 18 in the ONCOS-102 cohort. CONCLUSIONS: ONCOS-102 plus pemetrexed and cisplatin/carboplatin was well tolerated by patients with MPM. In injected tumors, ONCOS-102 promoted a proinflammatory environment, including T-cell infiltration, which showed association with survival at month 18.

Quantification and functional evaluation of CD40L production from the adenovirus vector ONCOS-401.

Adaptive immunity involves activation of T cells via antigen presentation by antigen presenting cells (APCs) along with the action of co-stimulatory molecules and pattern recognition receptors. Cluster of differentiation 40 (CD40) is one such costimulatory molecule that is expressed on APCs that binds to CD40 ligand (CD40L) on T helper cells and activates a signaling cascade, subsequently resulting in a wide range of immune and inflammatory responses. Considering its important role in regulation of immune response, CD40/40 L has been used for developing antitumor vaccines. In this study, we developed methods for evaluating and quantifying the activity of CD40L expressed from an adenovirus vector ONCOS-401. Our results show that the ONCOS-401 vector produces functional CD40L, which can bind and activate a NF-κB-dependent signaling cascade, leading to secreted embryonic alkaline phosphatase reporter production in HEK293-BLUE cells. In addition, quantification of CD40L production using enzyme-linked immunosorbent assay and HEK-293 BLUE reporter cells showed reproducibly higher recovery of CD40L from ONCOS-401 than from the negative control vector or uninfected cells with consistent inter and intra-assay precision. Thus, a rapid and easy method for quantifying and assessing CD40L production and activity from adenovirus vectors would support the assessment of efficacy of the vector for gene therapy - this was the objective of our study.

Combination of immunogenic oncolytic adenovirus ONCOS-102 with anti-PD-1 pembrolizumab exhibits synergistic antitumor effect in humanized A2058 melanoma huNOG mouse model.

Malignant melanoma is an aggressive type of skin cancer whose incidence is increasing globally. Although surgery is effective in early stage melanoma, patients with advanced melanoma only have a 20% 5-year survival rate. Hence, combinations of existing and new immunotherapy technologies and immunotherapeutic agents are being evaluated. ONCOS-102 is an oncolytic adenovirus armed with human GM-CSF and an Ad5/3 chimeric capsid. It has shown to be well tolerated in phase I study (NCT01598129) wherein it induced antitumor immunity, infiltration of CD8 + T cells to tumors, and up-regulation of PD-L1. We propose that ONCOS-102 could serve as an immunosensitizer in combination therapies with checkpoint inhibitors. In this preclinical study, we investigated the cytotoxicity of ONCOS-102 and pembrolizumab, an anti-PD-1 antibody, in four human melanoma cell lines, A375, A2058, SK-Mel-2 and SK-Mel-28. Humanized mice engrafted with A2058 melanoma cells showed significant tumor volume reduction after ONCOS-102 treatment. Combination of pembrolizumab with ONCOS-102 reduced tumor volume to an even greater extent, while pembrolizumab (200 µg, or 400 µg) did not show any therapeutic benefit by itself. Body weight loss, and metastasis were not significantly affected by any treatment. These data support the scientific rationale for the ongoing clinical study of combination therapy of ONCOS-102 and pembrolizumab for the treatment of melanoma (NCT03003676).

Phase I study with ONCOS-102 for the treatment of solid tumors - an evaluation of clinical response and exploratory analyses of immune markers.

BACKGROUND: We conducted a phase I study with a granulocyte macrophage colony stimulating factor (GMCSF)-expressing oncolytic adenovirus, ONCOS-102, in patients with solid tumors refractory to available treatments. The objectives of the study were to determine the optimal dose for further use and to assess the safety, tolerability and adverse event (AE) profile of ONCOS-102. Further, the response rate and overall survival were evaluated as well as preliminary evidence of disease control. As an exploratory endpoint, the effect of ONCOS 102 on biological correlates was examined. METHODS: The study was conducted using a classic 3 + 3 dose escalation study design involving 12 patients. Patients were repeatedly treated intratumorally with ONCOS-102 plus daily low-dose oral cyclophosphamide (CPO). Tumor response was evaluated with diagnostic positron emission tomography (PET) and computed tomography (CT). Tumor biopsies were collected at baseline and after treatment initiation for analysis of immunological correlates. Peripheral blood mononuclear cells (PBMCs) were collected at baseline and during the study to assess antigen specificity of CD8+ T cells by interferon gamma (IFNγ) enzyme linked immunospot assay (ELISPOT). RESULTS: No dose limiting toxicity (DLT) or maximum tolerated dose (MTD) was identified for ONCOS-102. Four out of ten (40 %) evaluable patients had disease control based on PET/CT scan at 3 months and median overall survival was 9.3 months. A short-term increase in systemic pro-inflammatory cytokines and a prominent infiltration of TILs to tumors was seen post-treatment in 11 out of 12 patients. Two patients showed marked infiltration of CD8+ T cells to tumors and concomitant systemic induction of tumor-specific CD8+ T cells. Interestingly, high expression levels of genes associated with activated TH1 cells and TH1 type immune profile were observed in the post-treatment biopsies of these two patients. CONCLUSIONS: ONCOS-102 is safe and well tolerated at the tested doses. All three examined doses may be used in further development. There was evidence of antitumor immunity and signals of clinical efficacy. Importantly, treatment resulted in infiltration of CD8+ T cells to tumors and up-regulation of PD-L1, highlighting the potential of ONCOS-102 as an immunosensitizing agent for combinatory therapies with checkpoint inhibitors. TRIAL REGISTRATION: NCT01598129. Registered 19/04/2012.

Local treatment of a pleural mesothelioma tumor with ONCOS-102 induces a systemic antitumor CD8+ T-cell response, prominent infiltration of CD8+ lymphocytes and Th1 type polarization.

Late stage cancer is often associated with reduced immune recognition and a highly immunosuppressive tumor microenvironment. The presence of tumor infiltrating lymphocytes (TILs) and specific gene-signatures prior to treatment are linked to good prognosis, while the opposite is true for extensive immunosuppression. The use of adenoviruses as cancer vaccines is a form of active immunotherapy to initialise a tumor-specific immune response that targets the patient's unique tumor antigen repertoire. We report a case of a 68-year-old male with asbestos-related malignant pleural mesothelioma who was treated in a Phase I study with a granulocyte-macrophage colony­stimulating factor (GM-CSF)-expressing oncolytic adenovirus, Ad5/3-D24-GMCSF (ONCOS-102). The treatment resulted in prominent infiltration of CD8+ lymphocytes to tumor, marked induction of systemic antitumor CD8+ T-cells and induction of Th1-type polarization in the tumor. These results indicate that ONCOS-102 treatment sensitizes tumors to other immunotherapies by inducing a T-cell positive phenotype to an initially T-cell negative tumor.