Cervera, Victor

5555 Background: Platinum-resistant/refractory ovarian cancer presents a significant therapeutic challenge and despite several attempts, immunotherapies have not delivered satisfactory results to be approved. Identifying biomarkers of response to novel therapies is crucial for personalizing treatments and improving patient outcomes, especially since certain patients do experience long term benefit after the treatment with pembrolizumab and igrelimogene litadenorepvec (TILT-123; an oncolytic adenovirus coding for TNF and IL-2). Methods: Tumor biopsies (n=62), ascites (n=8) and blood (n=234) were collected from 15 patients treated in the PROTA trial (Phase I, NCT05271318). These patients received pembrolizumab intravenously plus igrelimogene litadenorepvec intravenously, followed by local administration intratumorally or intraperitoneally. Sampling took place prior to therapy, during therapy and after it. Tumor proteome (IHC, mIF) and transcriptome was analyzed to assess immune changes and virus presence. Ascites and blood samples were assayed to measure cell counts, phenotypes, cytokine and protein counts, as well as for the presence of antiviral neutralizing antibodies (NAbs). Biological parameters were correlated with overall survival (OS), RECIST 1.1 evaluations and tumor size changes. For analysis of OS, logrank test was used. For group comparisons two-tailed Mann-Whitney U-test was used. Pearson or Spearman tests were used for correlations. Results: Patients experiencing a drop in circulating lymphocytes 8-24 hours after treatment were more likely to experience longer OS (p=0.044). Additionally, patients with a higher lymphocyte count at baseline experienced similar OS benefit (p=0.018) plus a positive correlation with disease control (p=0.023). Most patients (11/15) showed antiviral immunity at baseline but eventually all patients developed neutralizing activity, and the same was observed in ascites. The presence of NAbs at baseline as well as development of highest titers were positively correlated with longer OS (p=0.004) and disease control (p=0.003). Conclusions: Igrelimogene litadenorepvec and pembrolizumab are therapies designed to attract, activate and/or protect lymphocyte-mediated antitumor activity. These findings suggest that having a fit immune system able to mobilize effector immune cells as well as responding to immunostimulant agents increases therapeutic success. As a disease with few therapeutic options, ovarian cancer patients often receive multiple lines of chemotherapy that might decrease the efficacy of immediate immunotherapies. The potential use of these biomarkers will be studied in larger studies to validate their utility in guiding the use of immunotherapy in this challenging patient population. Clinical trial information: NCT05271318 .

2658 Background: Immune checkpoint inhibitors provide limited benefit in patients with immunologically cold tumors, characterized by a lack of T cells. This creates a niche for T cell-inducing agents such as TILT-123 (igrelimogene litadenorepvec, Ad5/3-E2F-D24-hTNFa-IRES-hIL2). While the 5/3 chimeric oncolytic adenovirus platform prompts potent immunogenic capacity per se, this virus has been armed with TNFa and IL-2 selected based on their ability to activate and attract T cells into tumors. TILT-123 capsid modification, and double selectivity devices for virus replication in cancer cells only, allow intravenous use of TILT-123. This is an important advantage over conventional oncolytic viruses whose widespread use has been hindered by the need for intratumoral injection. Methods: Here we report tumor transduction, pharmacokinetic and immune effects of a single intravenous administration of TILT-123 from three Phase 1 dose escalation clinical trials (TUNIMO-NCT04695327, TUNINTIL-NCT04217473, and PROTA-NCT05271318), with a total of 52 patients. Overall, the most common tumor types were melanoma (20), ovarian cancer (18) and sarcoma (7). In each of these trials, the first TILT-123 injection was performed intravenously, and a tumor biopsy collected 7 days later. Peripheral blood was collected before and after systemic TILT-123 treatment. No other therapy was administered concurrently. Presence of virus in blood was detected with qPCR, while presence of virus in tumor biopsies was measured with immunohistochemistry (IHC) for adenovirus proteins. Immune changes in tumors were evaluated by IHC. Results: TILT-123 was detected in the peripheral blood of all treated patients. Virus concentration was highest at 1 hour after administration, with lower levels seen 16 hours post-injection. Concurrently, IFN-γ levels increased in the patients´ serum. The lowest TILT-123 blood concentrations were observed with the lowest dose, with progressive increases in subsequent cohorts. At higher doses, TILT-123 was detected circulating in blood one week post-administration. Treatment was safe and no dose-limiting toxicity was encountered. Overall, signs of TILT-123 transduction in tumors were observed in 75% of patients evaluated in all three trials, 80% in TUNIMO patients, and 63.64% in TUNINTIL patients. Early results from PROTA suggest a positive effect of TILT-123 in tumors from all cohorts´ dosages studied. Conclusions: In summary, intravenous injection of TILT-123 results in persistence of the virus in peripheral blood for up to 7 days. Tumor transduction was observed in 75% of patients in three Phase I trials on day 8 post TILT-123 systemic administration. These data suggest that TILT-123 could be developed as an intravenous therapy. However, further increases in tumor transduction could be achieved by using multiple intravenous injections of TILT-123. Clinical trial information: NCT04695327 ; NCT04217473 ; NCT05271318 .

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 .