Background Oncolytic viruses (OVs) are promising immunotherapeutics to treat immunologically cold tumors. However, research on the mechanism of action of OVs in humans and clinically relevant biomarkers is still sparse. To induce strong T-cell responses against solid tumors, TILT-123 (Ad5/3-E2F-d24-hTNFa-IRES-hIL2, igrelimogene litadenorepvec) was developed. TILT-123 encodes two transgenes: tumor necrosis alpha (TNFa) and interleukin-2 (IL-2). TUNIMO (NCT04695327) was a phase I clinical trial using TILT-123 in patients with advanced solid tumors aiming to assess the safety, efficacy, and immunological effects of TILT-123. Research presented in this study evaluated the immunological effects of TILT-123 in the TUNIMO trial by using biological samples collected from the patients during the study, with an objective to leverage the findings to develop possible biomarkers of response and gain insights into possible synergistic combination treatments.Methods 20 patients with advanced solid tumors were treated with TILT-123. Response to therapy was assessed with contrast-enhanced CT and fluorodeoxyglucose positron emission tomography, along with overall survival (OS) calculation. Biological samples from patients were collected in the form of blood and tumor biopsies. Collected samples were analyzed with immunohistochemistry, transcriptomics, proteomics, and flow cytometry.Results TILT-123 induced cyclical decreases in blood lymphocyte count, and more substantial blood lymphocyte count correlated with better radiographical response and longer OS. Lymphocyte count findings were confirmed with external control dataset of 96 patients. More substantial lymphocyte count change was linked to stronger immune activation in plasma proteome after intravenous TILT-123 and the presence of TILT-123 mRNA in tumors. Regarding other assays. tumor biopsies profiled showed increased amounts of CD8+ T cells, CD4+ T cells and NK cells after intravenous TILT-123, but not after intratumoral TILT-123. Transcriptional differences were seen in tumors after intravenous therapy and intratumoral therapy, with patients benefitting therapy showing stronger downregulation of immune activation at all time points.Conclusions TILT-123 therapy induced accumulation of effector lymphocytes in tumors. Peripheral lymphocyte count decrease is a promising biomarker for assessing oncolytic adenovirus therapy response.

Abstract Immune checkpoint inhibitors have demonstrated modest efficacy as a monotherapy in ovarian cancer. Originally developed to improve efficacy of T-cell therapies such as immune checkpoint inhibitors and adoptive cell transfer, TILT-123 (Ad5/3-E2F-D24-hTNFα-IRES-hIL-2) is a serotype chimeric oncolytic adenovirus encoding tumor necrosis factor alpha and interleukin-2. Here we report results from phase 1a of PROTA, a single-arm, multicentre dose escalation trial with TILT-123 and pembrolizumab in female patients with platinum resistant or refractory ovarian cancer (NCT05271318). The primary endpoint was safety. Secondary endpoints included efficacy, tolerability, virus persistence and anti-viral immunity. Patients (n = 15) received intravenous and intraperitoneal and/or intratumoral injections of TILT-123 as well as intravenous pembrolizumab. Treatment was well tolerated, and no dose-limiting toxicities were observed. The most frequent adverse events were fever (40%), fatigue (40%) and nausea (40%). Disease control was achieved in 64% of evaluable patients (9/14). Median progression-free survival and overall survival were 98 and 190 days respectively. Clinical responses were associated with higher serum anti-adenovirus neutralizing antibody titer at baseline and post-treatment. The phase 1b investigating TILT-123, pembrolizumab and PEGylated liposomal doxorubicin in a similar patient population is underway.

Background: Despite significant advancements in the treatment of malignant melanoma, metastatic mucosal melanoma remains a therapeutic challenge due to its complex pathogenesis, distinct pathological characteristics, and limited response to immunotherapy. Combining different immunotherapeutic approaches offers a potential strategy to address these challenges. Tumor-infiltrating lymphocyte (TIL) therapy and oncolytic virus therapy represent promising treatment modalities that may synergize with each other. Patient and methods: We present a case of a 48-year-old woman with metastatic sinonasal mucosal melanoma who achieved a durable complete pathological response following treatment with multiple injections of the oncolytic virus TILT-123 (igrelimogene litadenorepvec) and a single infusion of TILs, without preconditioning chemotherapy or postconditioning interleukin-2. Results: Immunohistochemical analysis and single-cell sequencing revealed interesting alterations in injected and noninjected tumors as well as in peripheral blood, during the treatment course, suggesting that TILT-123 facilitated TIL engraftment into the tumor, ultimately leading to a complete response. Conclusions: This case underscores the potential of combined immunotherapeutic approaches as a promising strategy for patients with metastatic mucosal melanoma.

AbstractPurpose: TILT-123 (igrelimogene litadenorepvec) is an oncolytic adenovirus armed with TNFa and IL2, designed to induce T-cell infiltration and cytotoxicity in solid tumors. Patients and Methods: TUNIMO (NCT04695327) was a single-arm, multicenter phase I dose-escalation trial designed to assess the safety of TILT-123 in advanced solid cancers refractory to standard therapy. Patients received intravenous and intratumoral TILT-123. The primary endpoint was safety by adverse events (AE), laboratory values, vital signs, and electrocardiograms. Secondary endpoints included tumor response, pharmacokinetics, and predictive biomarkers. Results: Twenty patients were enrolled, with a median age of 58 years. Most prevalent cancer types included sarcomas (35%), melanomas (15%) and ovarian cancers (15%). No dose-limiting toxicities were observed. The most frequent treatment-related AEs included fever (16.7%), chills (13.0%), and fatigue (9.3%). Ten patients were evaluable for response on day 78 with RECIST 1.1, iRECIST or PET-based evaluation. The disease control rate by PET was 6/10 (60% of evaluable patients) and 2/10 by RECIST 1.1 and iRECIST(20%of evaluable patients). Tumor size reductions occurred in both injected and non-injected lesions. TILT-123 was detected in injected and non-injected tumors, and virus was observed in blood after intravenous and intratumoral injections. Treatment resulted in reduction of lymphocytes in blood, with concurrent lymphocyte increases in tumors, findings compatible with trafficking. Conclusions: TILT-123 was safe and able to produce antitumor effects in local and distant lesions in heavily pre-treated patients. Good tolerability of TILT-123 facilitates combination studies, several of which are ongoing (NCT04217473, NCT05271318, NCT05222932, and NCT06125197). See related commentary by Silva-Pilipich and Smerdou, p. 3649

Supplementary Table S1-S5, Supplementary Figure S1-S6

Abstract Background A limitation of approved oncolytic viruses is their requirement for intratumoral (i.t.) injection. TILT-123 (igrelimogene litadenorepvec, Ad5/3-E2F-D24-hTNFα-IRES-hIL-2) is a chimeric oncolytic adenovirus suitable for intravenous (i.v.) delivery due to its capsid modification and dual selectivity devices. It is armed with tumor necrosis alpha and interleukin-2 for promoting T-cell activation and lymphocyte trafficking to tumors, thereby enhancing the antitumor immune response. Here, we present the findings after a single i.v. administration of TILT-123 in three phase I dose escalation clinical trials. Methods Patients with advanced solid tumors initially received a single i.v. dose of TILT-123 ranging from 3 × 109 to 4 × 1012 viral particles (VP). Blood was collected at baseline, 1, 16, and 192 h (7 days) post-treatment for bioavailability and serum analysis. Tumor biopsies were collected prior to treatment and 7 days post-treatment for analysis of viral presence and immunological effects. Patients did not receive any other cancer therapies during this period. Results Across all three trials (TUNIMO, TUNINTIL, and PROTA), 52 total patients were treated with i.v. TILT-123. Overall, TILT-123 was found to be well-tolerated, with no dose-limiting toxicities observed. Post-treatment tumor biopsies showed expression of viral genes, presence of TILT-123 adenovirus proteins or DNA, and changes in immune cell infiltration from baseline. Increased virus dose did not lead to increased virus detection in tumors. Median overall survival was longer in patients with confirmed presence of TILT-123 in post-treatment biopsies (280 versus 190 days, p = 0.0405). Conclusion TILT-123 demonstrated safety and significant intratumoral immunomodulation following a single i.v. administration, warranting further investigation. Trial registrations TUNIMO—NCT04695327. Registered 4 January 2021, https://clinicaltrials.gov/study/NCT04695327. TUNINTIL—NCT04217473. Registered 19 December 2019, https://clinicaltrials.gov/study/NCT04217473. PROTA—NCT05271318. Registered 4 February 2022, https://clinicaltrials.gov/study/NCT05271318.

Abstract Background TILT-123 (Ad5/3-E2F-D24-hTNFα-IRES-hIL-2) is a serotype chimeric dual safety device oncolytic adenovirus armed with tumor necrosis factor alpha and interleukin-2. It was designed to improve efficacy of T-cell therapies such as immune checkpoint blockade or adoptive cell transfer. We present biological and immunological endpoints from an open-label phase 1 dose escalation study of TILT-123 in combination with anti-PD-1 pembrolizumab in platinum resistant or refractory ovarian cancer patients. Experimental procedures In this dose escalation trial (NCT05271318), patients were first injected with an intravenous (i.v.) dose of TILT-123 ranging from 3x1011 to 4x1012 virus particles (VP), followed by five intratumoural (i.t.) or intraperitoneal (i.p.) injections ranging from 1x1011 to 5x1011 VP. Patients also received intravenous injections of 200 mg pembrolizumab every three weeks starting 36 days after the first dose of TILT-123. The primary endpoint was safety, while efficacy by RECIST1.1 was a secondary endpoint. Collection of tumor biopsies, circulating immune cells, serum, saliva, urine and feces enabled multi-omic evaluation of mechanism of action and identification of predictive biomarkers. Summary of data As of January 2nd 2024, 15 patients received trial therapy. No dose-limiting toxicities were observed and the most frequent AEs associated with therapy included chills and nausea (>10% of patients). Stable disease by RECIST 1.1 was seen in 67% in 12 evaluable patients. TILT-123 replication was detected in both injected and non-injected tumors as assessed by qPCR and anti-hexon IHC. Multiplex immunofluorescence demonstrated induction of robust immunological activity in both injected and non-injected tumors, including significant increase in granzyme B+, PD-1+ CD4+ and CD8+ T cells as well as PD-1+ NK cells. Baseline intratumoral CD4+, FOXP3+ regulatory T cells were not associated with clinical response. Tertiary lymphoid structures and lymphoid aggregates were identified in patients showing long term disease control. Low to medium titers of neutralizing antibodies against 5/3 chimeric adenovirus were detected in 57% of patients at baseline and were not a predictive factor of disease control. No patients had high titers at baseline. Conclusion TILT-123 in combination with anti-PD-1 pembrolizumab was safe and resulted in disease control in both platinum resistant and refractory ovarian cancer patients. Analysis of biological samples revealed insights into mechanism of action, including an immune profile predictive of clinical response. These results, together with those from four other trials (NCT04695327, NCT04217473, NCT06125197 and NCT05222932) set the stage for continued clinical evaluation of TILT-123. Citation Format: James H. Clubb, Matthew S. Block, Johanna Mäenpää, Santeri Pakola, Lyna Haybout, Dafne C. Quixabeira, Tatiana Kudling, Mirte van der Heijden, Elise Jirovec, Tuomo Alanko, Daniel A. Adamo, Susan Ramadan, Jorma Sormunen, Juha Kononen, Julia W. Cohen, Nadena Singh, John Goldfinch, Suvi Sorsa, Riikka Havunen, Claudia Kistler, João M. Santos, Víctor Cervera-Carrascon, Akseli Hemminki. Immunological activity of oncolytic adenovirus encoding TNFα and IL-2 (TILT-123) in combination with pembrolizumab in platinum resistant or refractory ovarian cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT139.

T cell-focused cancer immunotherapy including checkpoint inhibitors and cell therapies has been rapidly evolving over the past decade. Nevertheless, there remains a major unmet medical need in oncology generally and immuno-oncology specifically. We have constructed an oncolytic adenovirus, Ad5/3-E2F-d24-aMUC1aCD3-IL-2 (TILT-322), which is armed with a human aMUC1aCD3 T cell engager and IL-2. TILT-322 treatment stimulated T cell cytotoxicity through the increased presence of granzyme B, perforin, and interferon-gamma. Additional immune profiling indicated TILT-322 increased gamma delta T cell activation and impacted other cell types such as natural killer cells and natural killer-like T cells that are traditionally involved in cancer immunotherapy. TILT-322 treatment also decreased the proportion of exhausted CD8+ T cells as demarked by immune checkpoint expression in ovarian ascites samples. Overall, our data showed that TILT-322 treatment led to an enhanced T cell activation and reversed T cell exhaustion translating into high antitumor efficacy when given locally or intravenously. The analysis of blood and tumors isolated from an in vivo patient-derived ovarian cancer xenograft model suggested TILT-322 mediated tumor control through improved T cell functions. Therefore, TILT-322 is a promising novel anti-tumor agent for clinical translation.

5562 Background: Platinum-resistant or refractory ovarian cancer remains a hard-to-treat disease given the poor prognosis and survival rates. Immune checkpoint inhibitors (ICI; such as pembrolizumab) have not been approved in this indication. Igrelimogene litadenorepvec (Ad5/3-E2F-d24-hTNF-IRES-hIL2; TILT-123), is an oncolytic adenovirus encoding for IL-2 and TNFa, designed to selectively lyse tumor cells while recruiting and activating T-cells, turning immunologically cold tumors hot. The combination of these therapies is appealing as TILT-123 should allow pembrolizumab to be more active, while pembrolizumab should delay emergence of T-cell exhaustion. Methods: PROTA (NCT05271318) is a multicenter open-label phase 1 clinical trial initiated to investigate the safety of TILT-123 in combination with pembrolizumab, in participants bearing ovarian cancer resistant or refractory to platinum-based therapy. In a 3+3 dose-escalation design, TILT-123 was administered intravenously and intratumorally/intraperitoneally to participants with an injectable tumor or carcinomatosis. Pembrolizumab (200mg/Q3wk) was not altered. Eligibility criteria included adequate hepatic and renal functions, and WHO/ECOG performance status of 0-1. Primary endpoint was safety by day 92 evaluated based on adverse events, laboratory values, vital signs, and electrocardiogram. Secondary endpoints included anti-tumor response (RECIST1.1/iRECIST), CA125 levels, pharmacokinetics, transduction of tumors, immune response towards the virus and tumors. Data cutoff was 22Jan2024. Results: 15 patients were enrolled with a median age of 66 (36-78) years, and 14 were evaluable for treatment response with RECIST 1.1/iRECIST. 8 patients were platinum-resistant, and 7 patients were platinum-refractory. Majority of patients had WHO/ECOG performance status 1. Prevalent cancer histology was epithelial ovarian cancer, with some fallopian tube cancer and primary peritoneal cancer. Dose-limiting toxicities were not observed. Frequent grade 1-4 treatment-related AEs (>30% of patients) were anemia, nausea, lymphocyte count decreased, fever and diarrhea. Stable disease (SD) by RECIST1.1 was achieved in 64.3% of evaluable patients and CA125 decreased below baseline in 50% of the patients at least in one timepoint. Median PFS and OS in all patients were 105 and 280 days, respectively. In patients with SD on day 92 by RECIST1.1, median OS was 293 days and median PFS was 174 days. Tumor biopsies indicated the presence of virus and induction of T-cells in injected and non-injected lesions. Conclusions: Combination of TILT-123 and pembrolizumab is safe and appears to induce disease control in a difficult-to-treat patient population. Investigation of TILT-123, pembrolizumab and pegylated liposomal doxorubicin is ongoing in similar patients. Clinical trial information: NCT05271318 .

Background TILT-123 (Ad5/3-E2F-d24-hTNFa-IRES-hIL2) is an oncolytic adenovirus encoding tumor necrosis factor alpha (hTNFa) and interleukin 2 (hIL-2) designed to enhance immune cells' reactivity against cancer cells in cold tumor microenvironments. Following more than a decade of preclinical development, the virus has now reached clinical phase and multiple trials are underway in several indications in monotherapy and combination therapy settings. NCT04695327 (TUNIMO) is an open-label phase 1 multicenter trial evaluating the safety of TILT-123 as a monotherapy in advanced solid cancers. Safety and correlative analysis have been performed from multiple different biological matrices from patients to provide mechanistic insights to TILT-123 therapy. This study focused on patient blood samples collected during the trial. Methods First five cohorts of TUNIMO included 15 patients with various solid cancer types. Patients received multiple rounds of TILT-123 therapy, and blood was collected before and after therapy. Blood collected from the patients was analyzed for safety analysis through standard hospital protocols. Serum from the blood was extracted and analyzed with Olink Target 96 Immuno-Oncology Panel. Adverse events were assessed and collected by the study site investigators. Results TILT-123 therapy was well tolerated across all dosing cohorts. Transient lymphopenia and neutropenia with quick normalization was observed in patients receiving treatment. A trending increase in lymphocytes and neutrophils was observed across the study. Regarding safety, therapy was well tolerated with no untoward changes in liver safety values, kidney function tests or electrolytes even at highest dose levels. Total of 63 therapy related adverse events (AEs) were observed in the 15 patients treated. Clinically, most frequent AEs were fever, chills, neutropenia, and fatigue. No treatment related grade 5 AEs were reported. Proteomic profiling of the serums revealed high levels of pro-inflammatory cytokines and chemokines post treatment. Conclusions No significant toxicities related to TILT-123 therapy were observed clinically or in blood laboratory testing. Transient reduction in blood lymphocytes and neutrophils with quick normalization was observed after treatment. Even in this heavily pretreated patient population, proteomic analysis of serum indicated TILT-123's ability to induce pro-inflammatory changes associated with enhanced lymphocyte cytotoxicity and trafficking, providing encouraging results of activity in this group of patients with poor prognosis. Ethics Approval This study was approved by the Finnish National Committee on Medical Research Ethics (TUKIJA); approval number HUS/1804/2020.

Introduction Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer, but preclinical testing of hypotheses such as combination therapies has been complicated, in part due to species incompatibility issues. For example, one of few known permissive animal models for oncolytic adenoviruses is the Syrian hamster, for which an ICI, mainly an anti-PD-L1 monoclonal antibody (mAb) was not previously available. In this study, we developed an anti-Syrian hamster PD-L1 mAb to enable the evaluation of safety and efficacy, when combining anti-PD-L1 with an oncolytic adenovirus encoding tumour necrosis factor alpha (TNFα) and interleukin-2 (IL-2) (Ad5/3-E2F-D24-hTNFα-IRES-hIL-2 or TILT-123). Methods Recombinant Syrian hamster PD-L1 was expressed and mice immunized for mAb formation using hybridoma technology. Clonal selection through binding and functional studies in vitro, in silico and in vivo identified anti-PD-L1 clone 11B12-1 as the primary mAb candidate for immunotherapy modelling. The oncolytic virus (OV) and ICI combination approach was then evaluated using 11B12-1 and TILT-123 in a Syrian hamster model of pancreatic ductal adenocarcinoma (PDAC). Results Supernatants from hybridoma parent subclone 11B12B4 provided the highest positive PD-L1 signal, on Syrian hamster PBMCs and three cancer cell lines (HT100, HapT1 and HCPC1). In vitro co-cultures revealed superior immune modulated profiles of cell line matched HT100 tumour infiltrating lymphocytes when using subclones of 7G2, 11B12 and 12F1. Epitope binning and epitope prediction using AlphaFold2 and ColabFold revealed two distinct functional epitopes for clone 11B12-1 and 12F1-1. Treatment of Syrian hamsters bearing HapT1 tumours, with 11B12-1 induced significantly better (p<0.05) tumour growth control than isotype control by day 12. 12F1-1 did not induce significant tumour growth control. The combination of 11B12-1 with oncolytic adenovirus TILT-123 improved tumour growth control further, when compared to monotherapy (p<0.05) by day 26. Conclusions Novel Syrian hamster anti-PD-L1 clone 11B12-1 induces tumour growth control in a hamster model of PDAC. Combining 11B12-1 with oncolytic adenovirus TILT-123 improves tumour growth control further and demonstrates good safety and toxicity profiles.

While the presence of tumor-infiltrating lymphocytes (TILs) associates with improved survival prognosis in ovarian cancer (OvCa) patients, TIL therapy benefit is limited. Here, we evaluated an oncolytic adenovirus coding for a human variant IL-2 (vIL-2) cytokine, Ad5/3-E2F-d24-vIL2 (vIL-2 virus), also known as TILT-452, as an immunotherapeutic strategy to enhance TIL responsiveness towards advanced stage OvCa tumors. Fragments of resected human OvCa tumors were processed into single-cell suspensions, and autologous TILs were expanded from said samples. OvCa tumor specimens were co-cultured with TILs plus vIL-2 virus, and cell killing was assessed in real time through cell impedance measurement. Combination therapy was further evaluated in vivo through a patient-derived xenograft (PDX) ovarian cancer murine model. The combination of vIL-2 virus plus TILs had best cancer cell killing ex vivo compared to TILs monotherapy. These results were supported by an in vivo experiment, where the best OvCa tumor control was obtained when vIL-2 virus was added to TIL therapy. Furthermore, the proposed therapy induced a highly cytotoxic phenotype demonstrated by increased granzyme B intensity in NK cells, CD4+ T, and CD8+ T cells in treated tumors. Our results demonstrate that Ad5/3-E2F-d24-vIL2 therapy consistently improved TILs therapy cytotoxicity in treated human OvCa tumors.

Pancreatic ductal adenocarcinoma (PDAC) is a highly treatment-resistant cancer. Currently, the only curative treatment for PDAC is surgery, but most patients are diagnosed with metastatic disease and thus outside the scope of surgery. The majority of metastatic patients receive chemotherapy, but responses are limited. New therapeutics are thus urgently needed for PDAC. One major limitation in treating PDAC has been the highly immunosuppressive tumor microenvironment (TME) which inhibits anti-cancer immune responses. We have constructed an oncolytic adenovirus coding for a variant the interleukin 2 molecule, Ad5/3-E2F-d24-vIL2 (also known as TILT-452, and “vIL-2 virus”), with preferential binding to IL-2 receptors on the surface of effector lymphocytes over T regulatory cells (T regs). In the present study this virus was evaluated in combination with nab-paclitaxel and gemcitabine chemotherapy in Panc02 mouse model. Ad5/3-E2F-d24-vIL2 showed marked PDAC cell killing in vitro , alongside induction of mitotic slippage and immunogenic cell death in PDAC cell lines, when combined with chemotherapy. Increased survival was seen in vivo with 80% of animals surviving long term, when compared to chemotherapy alone. Moreover, combination therapy mediated enhanced tumor growth control, without observable toxicities in internal organs or external features. Survival and tumor control benefits were associated with activation of tumor infiltrating immune cells, downregulation of inhibitory signals, change in fibroblast populations in the tumors and changes in intratumoral cytokines, with increased chemokine amounts (CCL2, CCL3, CCL4) and anti-tumor cytokines (IFN-γ and TNFα). Furthermore, vIL-2 virus in combination with chemotherapy efficiently induced tumor protection upon rechallenge, that was extended to a previously non-encountered cancer cell line. In conclusion, Ad5/3-E2F-d24-vIL2 is a promising immunotherapy candidate when combined with nab-paclitaxel and gemcitabine.

Background Renal cell carcinoma (RCC) remains the most common type of kidney cancer. Despite being characterized by a rich and heterogenous immunogenic profile, a higher presence of immune content has been associated with poor prognosis, most likely due to an immunosuppressive tumor environment and following T cell exhaustion Thus, there is an unmet need for current immunotherapies against RCC to increase activation, but also a reduction of this exhausted and immunosuppressive state. In this case, we suggest that the use of oncolytic viruses (OVs) would contribute to reinforce the previously mentioned objectives, as they are well-known to induce a powerful immune response. In this study, we focus on Ad5/3-E2F-d24-hIL7 (also known as TILT-517), an oncolytic adenovirus expressing interleukin-7 (IL-7) which has been previously described to be effective in preclinical studies involving other tumor types.1 We believe that combining this virus with other immunotherapies such as Immune Checkpoint inhibitors (ICIs), which have previously shown synergies with other OVs and that are also part of RCC first-treatment line, might be beneficial to improve the therapeutic outcome. Hence, the aim is to evaluate the efficacy and explore the properties of Ad5/3-E2F-d24-hIL7 in RCC in combination with ICIs. Methods Patient derived ex-vivo tumors were obtained from RCC patients, processed, and treated with either human anti-PD-1 or anti-PD-L1 mAb, with or without Ad5/3-E2F-d24-hIL7. Cell viability was assessed through MTS assays to determine antitumor efficacy, and flow cytometry and other immunoprotein detection methods were used to evaluate changes in the immune landscape compared to non-treated RCC samples. Infection of the samples was also verified through qPCR against viral genes. Results The use of Ad5/3-E2F-d24-hIL7 in combination with ICIs offered better antitumor efficacy than ICIs monotherapies. Virus replication (oncolysis) was not compromised by their presence. In addition, changes in the tumor immune microenvironment were evaluated in all groups. Significant differences in the percentage of immune cell populations such as CD4+, CD8+ T cells as well as NK cells were detected after treatment exposure, in both activated and exhausted T cell subsets. Similar and corresponding effects were observed when analyzing the presence of cytokines from supernatants from treated samples. Conclusions We demonstrate that combining Ad5/3-E2F-d24-hIL7 with either aPD-1 or aPD-L1 increases antitumor efficacy and changes in the tumor immune microenvironment in ex-vivo RCC tumor histocultures. This combination therapy holds promise as a novel immunotherapeutic strategy for RCC, and the data obtained warrant translation into a clinical setting. Reference Kudling TV, Clubb JHA, Quixabeira DCA, Santos JM, Havunen R, Kononov A, Heiniö C, Cervera-Carrascon V, Pakola S, Basnet S, Grönberg-Vähä-Koskela S, Arias V, Gladwyn-Ng I, Aro K, Bäck L, Räsänen J, Ilonen I, Borenius K, Räsänen M, … Hemminki A. Local delivery of interleukin 7 with an oncolytic adenovirus activates tumor-infiltrating lymphocytes and causes tumor regression. Oncoimmunology, 2022;11(1). Ethics Approval Cancer samples were collected from the patients undergoing surgical resection at the Helsinki University Central Hospital (HUS, Helsinki, Finland). Sample collection was approved by HUS Operatives Ethics Committee (permit numbers HUS/850/2017, HUS/3360/2019 and HUS/259/2021) and the patients gave their written consent.