Oncolytic adenovirus decreases the proportion of TIM-3+ subset of tumor-infiltrating CD8+ T cells with correlation to improved survival in patients with cancer

BACKGROUND

Oncolytic viruses are a potent form of active immunotherapy, capable of invoking antitumor T-cell responses. Meanwhile, less is known about their effects on immune checkpoints, the main targets for passive immunotherapy of cancer. T-cell immunoglobulin and mucin domain-3 (TIM-3) is a coinhibitory checkpoint driving T-cell exhaustion in cancer. Here we investigated the effects of oncolytic adenovirus on the TIM-3 checkpoint on tumor-infiltrating immune cells and clinical impact in patients with cancer receiving oncolytic immunotherapy.

METHODS

Modulation of TIM-3 expression on tumor-infiltrating immune cells was studied preclinically in B16 melanoma following intratumoral treatment with Ad5/3∆24-granulocyte-macrophage colony-stimulating factor oncolytic adenovirus. We conducted a retrospective longitudinal analysis of 15 patients with advanced-stage cancer with tumor-site biopsies before and after oncolytic immunotherapy, treated in the Advanced Therapy Access Program (ISRCTN10141600, April 5, 2011). Following patient stratification with regard to TIM-3 (increase vs decrease in tumors), overall survival and imaging/marker responses were evaluated by log-rank and Fisher's test, while coinhibitory receptors/ligands, transcriptomic changes and tumor-reactive and tumor-infltrating immune cells in biopsies and blood samples were studied by microarray rank-based statistics and immunoassays.

RESULTS

Preclinically, TIM-3+ tumor-infiltrating lymphocytes (TILs) in B16 melanoma showed an exhausted phenotype, whereas oncolytic adenovirus treatment significantly reduced the proportion of TIM-3+ TIL subset through recruitment of less-exhausted CD8+ TIL. Decrease of TIM-3 was observed in 60% of patients, which was associated with improved overall survival over TIM-3 increase patients (p=0.004), together with evidence of clinical benefit by imaging and blood analyses. Coinhibitory T-cell receptors and ligands were consistently associated with TIM-3 changes in gene expression data, while core transcriptional exhaustion programs and T-cell dysfunction were enriched in patients with TIM-3 increase, thus identifying patients potentially benefiting from checkpoint blockade. In striking contrast, patients with TIM-3 decrease displayed an acute inflammatory signature, redistribution of tumor-reactive CD8+ lymphocytes and higher influx of CD8+ TIL into tumors, which were associated with the longest overall survival, suggesting benefit from active immunotherapy.

CONCLUSIONS

Our results indicate a key role for the TIM-3 immune checkpoint in oncolytic adenoviral immunotherapy. Moreover, our results identify TIM-3 as a potential biomarker for oncolytic adenoviruses and create rationale for combination with passive immunotherapy for a subset of patients.

Hypoxia-inducible factor activity promotes antitumor effector function and tissue residency by CD8+ T cells

Adoptive T cell therapies (ACTs) hold great promise in cancer treatment, but low overall response rates in patients with solid tumors underscore remaining challenges in realizing the potential of this cellular immunotherapy approach. Promoting CD8+ T cell adaptation to tissue residency represents an underutilized but promising strategy to improve tumor-infiltrating lymphocyte (TIL) function. Here, we report that deletion of the HIF negative regulator von Hippel-Lindau (VHL) in CD8+ T cells induced HIF-1α/HIF-2α-dependent differentiation of tissue-resident memory-like (Trm-like) TILs in mouse models of malignancy. VHL-deficient TILs accumulated in tumors and exhibited a core Trm signature despite an exhaustion-associated phenotype, which led to retained polyfunctionality and response to αPD-1 immunotherapy, resulting in tumor eradication and protective tissue-resident memory. VHL deficiency similarly facilitated enhanced accumulation of chimeric antigen receptor (CAR) T cells with a Trm-like phenotype in tumors. Thus, HIF activity in CD8+ TILs promotes accumulation and antitumor activity, providing a new strategy to enhance the efficacy of ACTs.

Oncograms Visualize Factors Influencing Long-Term Survival of Cancer Patients Treated with Adenoviral Oncolytic Immunotherapy

The first US Food and Drug Administration (FDA)- and EMA-approved oncolytic virus has been available since 2015. However, there are no markers available that would predict benefit for the individual patient. During 2007–2012, we treated 290 patients with advanced chemotherapy-refractory cancers, using 10 different oncolytic adenoviruses. Treatments were given in a Finnish Medicines Agency (FIMEA)-regulated individualized patient treatment program (the Advanced Therapy Access Program [ATAP]), which required long-term follow-up of patients, which is presented here. Focusing on the longest surviving patients, some key clinical and biological features are presented as “oncograms.” Some key attributes that could be captured in the oncogram are suggested to predict treatment response and survival after oncolytic adenovirus treatment. The oncogram includes immunological laboratory parameters assessed in peripheral blood (leukocytes, neutrophil-to-lymphocyte ratio, interleukin-8 [IL-8], HMGB1, anti-viral neutralizing antibody status), features of the patient (gender, performance status), tumor features (histological tumor type, tumor load, region of metastases), and oncolytic virus-specific features (arming of the virus). The retrospective approach used here facilitates verification in a prospective controlled trial setting. To our knowledge, the oncogram is the first holistic attempt to identify the patients most likely to benefit from adenoviral oncolytic virotherapy.

Interleukin 8 activity influences the efficacy of adenoviral oncolytic immunotherapy in cancer patients

After the landmark approval of T-VEC, oncolytic viruses are finding their way to the clinics. However, response rates have still room for improvement, and unfortunately there are currently no available markers to predict responses for oncolytic immunotherapy. Interleukin 8 (IL-8) production is upregulated in many cancers and it also connects to several pathways that have been shown to impair the efficacy of adenoviral immunotherapy. We studied the role of IL-8 in 103 cancer patients treated with oncolytic adenoviruses. We found high baseline serum IL-8 concentration to be independently associated with poor prognosis (p<0.001). Further, normal baseline IL-8 was associated with improved prognostic potential of calculation of the neutrophil-to-lymphocyte ratio (p<0.001). Interestingly, a decrease in IL-8 concentration after treatment with oncolytic adenovirus predicted better overall survival (p<0.001) and higher response rate, although this difference was not significant (p=0.066). We studied the combination of adenovirus and IL-8 neutralizing antibody ex vivo in single cell suspensions and in co-cultures of tumor-associated CD15+ neutrophils and CD3+ tumor-infiltrating lymphocytes derived from fresh patient tumor samples. These results indicate a role for IL-8 as a biomarker in oncolytic virotherapy, but additionally provide a rationale for targeting IL-8 to improve treatment efficacy. In conclusion, curtailing the activity of IL-8 systemically or locally in the tumor microenvironment could improve anti-tumor immune responses resulting in enhanced efficacy of adenoviral immunotherapy of cancer.

Oncolytic Adenovirus Expressing Monoclonal Antibody Trastuzumab for Treatment of HER2-Positive Cancer

Monoclonal anti-HER2 antibody trastuzumab has significantly improved the survival of patients with HER2-overexpressing tumors. Nevertheless, systemic antibody therapy is expensive, limited in efficacy due to physical tumor barriers, and carries the risk of severe side effects such as cardiomyopathy. Oncolytic viruses mediate cancer-selective transgene expression, kill infected cancer cells while mounting antitumor immune responses, and have recently demonstrated promising efficacy in combination treatments. Here, we armed an oncolytic adenovirus with full-length trastuzumab to achieve effective in situ antibody production coupled with progressive oncolytic cancer cell killing. We constructed an infectivity-enhanced serotype 5 oncolytic adenovirus, Ad5/3-Δ24-tras, coding for human trastuzumab antibody heavy- and light-chain genes, connected by an internal ribosome entry site. Infected cancer cells were able to assemble full-length functional antibody, as confirmed by Western blot, ELISA, and antibody-dependent cell-mediated cytotoxicity assay. Importantly, oncolysis was required for release of the antibody into tumors, providing additional spatial selectivity. Ad5/3-Δ24-tras showed potent in vitro cytotoxicity and enhanced antitumor efficacy over oncolytic control virus Ad5/3-Δ24 or commercial trastuzumab in HER2-positive cancer models in vivo (both P < 0.05). Furthermore, Ad5/3-Δ24-tras resulted in significantly higher tumor-to-systemic antibody concentrations (P < 0.001) over conventional delivery. Immunological analyses revealed dendritic cell activation and natural killer cell accumulation in tumor-draining lymph nodes. Thus, Ad5/3-Δ24-tras is an attractive anticancer approach combining oncolytic immunotherapy with local trastuzumab production, resulting in improved in vivo efficacy and immune cell activation in HER2-positive cancer. Moreover, the finding that tumor cells can produce functional antibody as directed by oncolytic virus could lead to many valuable antitumor approaches. Mol Cancer Ther; 15(9); 2259-69. ©2016 AACR.

Immunological data from cancer patients treated with Ad5/3-E2F-Δ24-GMCSF suggests utility for tumor immunotherapy

Oncolytic viruses that selectively replicate in tumor cells can be used for treatment of cancer. Accumulating data suggests that virus induced oncolysis can enhance anti-tumor immunity and break immune tolerance. To capitalize on the immunogenic nature of oncolysis, we generated a quadruple modified oncolytic adenovirus expressing granulocyte-macrophage colony-stimulating factor (GMCSF). Ad5/3-E2F-Δ24-GMCSF (CGTG-602) was engineered to contain a tumor specific E2F1 promoter driving an E1 gene deleted at the retinoblastoma protein binding site (“Δ24”). The fiber features a knob from serotype 3 for enhanced gene delivery to tumor cells. The virus was tested preclinically in vitro and in vivo and then 13 patients with solid tumors refractory to standard therapies were treated. Treatments were well tolerated and frequent tumor- and adenovirus-specific T-cell immune responses were seen. Overall, with regard to tumor marker or radiological responses, signs of antitumor efficacy were seen in 9/12 evaluable patients (75%). The radiological disease control rate with positron emission tomography was 83% while the response rate (including minor responses) was 50%. Tumor biopsies indicated accumulation of immunological cells, especially T-cells, to tumors after treatment. RNA expression analyses of tumors indicated immunological activation and metabolic changes secondary to virus replication.

Oncolytic virotherapy for treatment of breast cancer, including triple-negative breast cancer

Breast cancer is a heterogeneous disease, characterized by several distinct biological subtypes, among which triple-negative breast cancer (TNBC) is one associated with a poor prognosis. Oncolytic virus replication is an immunogenic phenomenon, and viruses can be armed with immunostimulatory molecules to boost virus triggered antitumoral immune responses. Cyclophosphamide (CP) is a chemotherapy drug that is associated with cytotoxicity and immunosuppression at higher doses, whereas immunostimulatory and anti-angiogenic properties are observed at low continuous dosage. Therefore, the combination of oncolytic immuno-virotherapy with low-dose CP is an appealing approach. We investigated the potency of oncolytic adenovirus Ad5/3-D24-GMCSF on a TNBC cell line and in vivo in an orthotopic xenograft mouse model, in combination with low-dose CP or its main active metabolite 4-hydroperoxycyclophosphamide (4-HP-CP). Furthermore, we summarized the breast cancer-specific human data on this virus from the Advanced Therapy Access Program (ATAP). Low-dose CP increased the efficacy of Ad5/3-D24-GMCSF in vitro and in a TNBC mouse model. In ATAP, treatments appeared safe and well-tolerated. Thirteen out of 16 breast cancer patients treated were evaluable for possible benefits with modified RECIST 1.1 criteria: 1 patient had a minor response, 2 had stable disease (SD), and 10 had progressive disease (PD). One patient is alive at 1,771 d after treatment. Ad5/3-D24-GMCSF in combination with low-dose CP showed promising efficacy in preclinical studies and possible antitumor activity in breast cancer patients refractory to other forms of therapy. This preliminary data supports continuing the clinical development of oncolytic adenoviruses for treatment of breast cancer, including TNBC.

Treatment of melanoma with a serotype 5/3 chimeric oncolytic adenovirus coding for GM-CSF: Results in vitro, in rodents and in humans

Metastatic melanoma is refractory to irradiation and chemotherapy, but amenable to immunological approaches such as immune-checkpoint-inhibiting antibodies or adoptive cell therapies. Oncolytic virus replication is an immunogenic phenomenon, and viruses can be armed with immunostimulatory molecules. Therefore, oncolytic immuno-virotherapy of malignant melanoma is an appealing approach, which was recently validated by a positive phase 3 trial. We investigated the potency of oncolytic adenovirus Ad5/3-D24-GMCSF on a panel of melanoma cell lines and animal models, and summarized the melanoma-specific human data from the Advanced Therapy Access Program (ATAP). The virus effectively eradicated human melanoma cells in vitro and subcutaneous SK-MEL-28 melanoma xenografts in nude mice when combined with low-dose cyclophosphamide. Furthermore, virally-expressed granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulated the differentiation of human monocytes into macrophages. In contrast to human cells, RPMI 1846 hamster melanoma cells exhibited no response to oncolytic viruses and the chimeric 5/3 fiber failed to increase the efficacy of transduction, suggesting limited utility of the hamster model in the context of viruses with this capsid. In ATAP, treatments appeared safe and well-tolerated. Four out of nine melanoma patients treated were evaluable for possible therapy benefit with modified RECIST criteria: one patient had minor response, two had stable disease, and one had progressive disease. Two patients were alive at 559 and 2,149 days after treatment. Ad5/3-D24-GMCSF showed promising efficacy in preclinical studies and possible antitumor activity in melanoma patients refractory to other forms of therapy. This data supports continuing the clinical development of oncolytic adenoviruses for treatment of malignant melanoma.

Serum HMGB1 is a predictive and prognostic biomarker for oncolytic immunotherapy

With the emergence of effective immunotherapeutics, which nevertheless harbor the potential for toxicity and are expensive to use, biomarkers are urgently needed for identification of cancer patients who respond to treatment. In this clinical-epidemiological study of 202 cancer patients treated with oncolytic adenoviruses, we address the biomarker value of serum high-mobility group box 1 (HMGB1) protein. Overall survival and imaging responses were studied as primary endpoints and adjusted for confounding factors in two multivariate analyses (Cox and logistic regression). Mechanistic studies included assessment of circulating tumor-specific T-cells by ELISPOT, virus replication by quantitative PCR, and inflammatory cytokines by cytometric bead array. Patients with low HMGB1 baseline levels (below median concentration) showed significantly improved survival (p = 0.008, Log-Rank test) and radiological disease control rate (49.2% vs. 30.0%, p = 0.038, χ² test) as compared to high-baseline patients. In multivariate analyses, the low HMGB1 baseline status was a strong prognostic (HR 0.638, 95% CI 0.462–0.881) and the best predictive factor for disease control (OR 2.618, 95% CI 1.004–6.827). Indicative of an immune-mediated mechanism, antitumor T-cell activity in blood and response to immunogenic-transgene coding viruses associated with improved outcome only in HMGB1-low patients. Our results suggest that serum HMGB1 baseline is a useful prognostic and predictive biomarker for oncolytic immunotherapy with adenoviruses, setting the stage for prospective clinical studies.

Serotype chimeric oncolytic adenovirus coding for GM-CSF for treatment of sarcoma in rodents and humans

Sarcomas are a relatively rare cancer, but often incurable at the late metastatic stage. Oncolytic immunotherapy has gained attention over the past years, and a wide range of oncolytic viruses have been delivered via intratumoral injection with positive safety and promising efficacy data. Here, we report preclinical and clinical results from treatment of sarcoma with oncolytic adenovirus Ad5/3-D24-GMCSF (CGTG-102). Ad5/3-D24-GMCSF is a serotype chimeric oncolytic adenovirus coding for human granulocyte-macrophage colony-stimulating factor (GM-CSF). The efficacy of Ad5/3-D24-GMCSF was evaluated on a panel of soft-tissue sarcoma (STS) cell lines and in two animal models. Sarcoma specific human data were also collected from the Advanced Therapy Access Program (ATAP), in preparation for further clinical development. Efficacy was seen in both in vitro and in vivo STS models. Fifteen patients with treatment-refractory STS (13/15) or primary bone sarcoma (2/15) were treated in ATAP, and treatments appeared safe and well-tolerated. A total of 12 radiological RECIST response evaluations were performed, and two cases of minor response, six cases of stable disease and four cases of progressive disease were detected in patients progressing prior to virus treatment. Overall, the median survival time post treatment was 170 days. One patient is still alive at 1,459 days post virus treatment. In summary, Ad5/3-D24-GMCSF appears promising for the treatment of advanced STS; a clinical trial for treatment of refractory injectable solid tumors including STS is ongoing.

Fc-gamma receptor polymorphisms as predictive and prognostic factors in patients receiving oncolytic adenovirus treatment

BACKGROUND

Oncolytic viruses have shown potential as cancer therapeutics, but not all patients seem to benefit from therapy. Polymorphisms in Fc gamma receptors (FcgRs) lead to altered binding affinity of IgG between the receptor allotypes and therefore contribute to differences in immune defense mechanisms. Associations have been identified between FcgR polymorphisms and responsiveness to different immunotherapies. Taken together with the increasing understanding that immunological factors might determine the efficacy of oncolytic virotherapy we studied whether FcgR polymorphisms would have prognostic and/or predictive significance in the context of oncolytic adenovirus treatments.

METHODS

235 patients with advanced solid tumors were genotyped for two FcgR polymorphisms, FcgRIIa-H131R (rs1801274) and FcgRIIIa-V158F (rs396991), using TaqMan based qPCR. The genotypes were correlated with patient survival and tumor imaging data.

RESULTS

In patients treated with oncolytic adenoviruses, overall survival was significantly shorter if the patient had an FcgRIIIa-VV/ FcgRIIa-HR (VVHR) genotype combination (P = 0,032). In contrast, patients with FFHR and FFRR genotypes had significantly longer overall survival (P = 0,004 and P = 0,006, respectively) if they were treated with GM-CSF-armed adenovirus in comparison to other viruses. Treatment of these patients with unarmed virus correlated with shorter survival (P < 0,0005 and P = 0,016, respectively). Treating FFHH individuals with CD40L-armed virus resulted in longer survival than treatment with other viruses (P = 0,047).

CONCLUSIONS

Our data are compatible with the hypothesis that individual differences in effector cell functions, such as NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and tumor antigen presentation by APCs caused by polymorphisms in FcgRs could play role in the effectiveness of oncolytic virotherapies. If confirmed in larger populations, FcgR polymorphisms could have potential as prognostic and predictive biomarkers for oncolytic adenovirus therapies to enable better selection of patients for clinical trials. Also, putative associations between genotypes, different viruses and survival implicate potentially important mechanistic issues.

Antiviral and antitumor T-cell immunity in patients treated with GM-CSF-coding oncolytic adenovirus

PURPOSE

Multiple injections of oncolytic adenovirus could enhance immunologic response. In the first part of this article, the focus was on immunologic aspects. Sixty patients previously naïve to oncolytic virus and who had white blood cells available were treated. Thirty-nine of 60 were assessed after a single virus administration, whereas 21 of 60 received a "serial treatment" consisting of three injections within 10 weeks. In the second part, we focused on 115 patients treated with a granulocyte macrophage colony-stimulating factor (GM-CSF)-coding capsid chimeric adenovirus, CGTG-102.

RESULTS

Following serial treatment, both increase and decrease in antitumor T cells in blood were seen more frequently, findings which are compatible with induction of T-cell immunity and trafficking of T cells to tumors, respectively. Safety was good in both groups. In 115 patients treated with CGTG-102 (Ad5/3-D24-GMCSF), median overall survival was 111 days following single and 277 days after serial treatment in nonrandomized comparison. Switching the virus capsid for avoiding neutralizing antibodies in a serial treatment featuring three different viruses did not impact safety or efficacy. A correlation between antiviral and antitumor T cells was seen (P = 0.001), suggesting that viral oncolysis can result in epitope spreading and breaking of tumor-associated immunologic tolerance. Alternatively, some patients may be more susceptible to induction of T-cell immunity and/or trafficking.

CONCLUSIONS

These results provide the first human data linking antiviral immunity with antitumor immunity, implying that oncolytic viruses could have an important role in cancer immunotherapy.

Induction of interferon pathways mediates in vivo resistance to oncolytic adenovirus

Oncolytic adenoviruses are an emerging experimental approach for treatment of tumors refractory to available modalities. Although preclinical results have been promising, and clinical safety has been excellent, it is also apparent that tumors can become virus resistant. The resistance mechanisms acquired by advanced tumors against conventional therapies are increasingly well understood, which has allowed development of countermeasures. To study this in the context of oncolytic adenovirus, we developed two in vivo models of acquired resistance, where initially sensitive tumors eventually gain resistance and relapse. These models were used to investigate the phenomenon on RNA and protein levels using two types of analysis of microarray data, quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry. Interferon (IFN) signaling pathways were found upregulated and Myxovirus resistance protein A (MxA) expression was identified as a marker correlating with resistance, while transplantation experiments suggested a role for tumor stroma in maintaining resistance. Furthermore, pathway analysis suggested potential therapeutic targets in oncolytic adenovirus-resistant cells. Improved understanding of the antiviral phenotype causing tumor recurrence is of key importance in order to improve treatment of advanced tumors with oncolytic adenoviruses. Given the similarities between mechanisms of action, this finding might be relevant for other oncolytic viruses as well.

Adenoviral E4orf3 and E4orf6 proteins, but not E1B55K, increase killing of cancer cells by radiotherapy in vivo

PURPOSE

Radiotherapy is widely used for treatment of many tumor types, but it can damage normal tissues. It has been proposed that cancer cells can be selectively sensitized to radiation by adenovirus replication or by using radiosensitizing transgenes. Adenoviral proteins E1B55K, E4orf3, and E4orf6 play a role in radiosensitization, by targeting the Mre11, Rad50, and NBS1 complex (MRN) and inhibiting DNA double-strand break (DSB) repair. We hypothesize that combined with irradiation, these adenoviral proteins increase cell killing through the impairment of DSB repair.

METHODS AND MATERIALS

We assessed the radiosensitizing/additive potential of replication-deficient adenoviruses expressing E1B55K, E4orf3, and E4orf6 proteins. Combination treatments with low-dose external photon beam radiotherapy were studied in prostate cancer (PC-3MM2 and DU-145), breast cancer (M4A4-LM3), and head and neck cancer (UT-SCC8) cell lines. We further demonstrated radiosensitizing or additive effects in mice with PC-3MM2 tumors.

RESULTS

We show enhanced cell killing with adenovirus and radiation combination treatment. Co-infection with several of the viruses did not further increase cell killing, suggesting that both E4orf6 and E4orf3 are potent in MRN inhibition. Our results show that adenoviral proteins E4orf3 and E4orf6, but not E1B55K, are effective also in vivo. Enhanced cell killing was due to inhibition of DSB repair resulting in persistent double-strand DNA damage, indicated by elevated phospho-H2AX levels at 24 h after irradiation.

CONCLUSIONS

This knowledge can be applied for improving the treatment of malignant tumors, such as prostate cancer, for development of more effective combination therapies and minimizing radiation doses and reducing side effects.