e17560 Background: Ovarian cancer (OC) ranks fifth among cancer deaths in women and remains the deadliest of all gynecological cancers. OncoTherad is a nanostructured complex developed by University of Campinas/Brazil, which exhibits immunomodulatory and antitumor properties. Erythropoietin (EPO) can exert non-hematopoietic functions and the association of immunotherapy and EPO is a reality in anemic patients due to cancer or chemotherapy who may use immunotherapies. We evaluated the effects of OncoTherad and EPO, alone or in combination, on PD-1/PDL-1 and CTLA-4 checkpoints, pro-angiogenic (VEGF) and anti-angiogenic (Endostatin) markers, and microvessel density (CD31-labeled capillaries) in chemically induced ovarian cancer in rats. Methods: Thirty-five Fischer rats were distributed into groups: Control (Sham surgery); Cancer (7,12-dimethylbenzoanthracene – DMBA injection in the ovarian bursa, 1.25 mg/kg); OncoTherad (20mg/kg); EPO (8.4 µg/kg); and OncoTherad+EPO (same doses of the isolated treatments). Intraperitoneal doses were administered twice a week for 4 weeks. Immunohistochemistry was analyzed as total immunoreactivity and intensity of immunoreaction. Results: The Cancer group showed an increase (p < 0.05) in microvascular density and histopathological lesions, predominantly high-grade dysplasias with non-metastatic phenotype, which was related to the little involvement of PD-1/PD-L1 and CTLA-4 checkpoints in this carcinogenesis stage. The treatments altered the frequency of ovarian lesions, especially OncoTherad promoted a significant reduction of cystic lesions, while in the EPO group there was marked hyperplasia of the interstitial tissue and the associated treatment led to intermediate results. OncoTherad immunotherapy was effective in reducing angiogenesis, promoting a decrease (p < 0.05) in VEGF immunostaining and microvessel count, and an increase (p < 0.05) in endostatin immunoreactivity. EPO treatment decreased (p < 0.05) endostatin levels in comparison with OncoTherad group and led to a weaker (p < 0.05) immunoreaction intensity of PD-1/PD-L1 and CTLA-4 compared to the Cancer group. These effects might be related to the modification of the tumor microenvironment modulated by EPO with a decrease in the population of immune cells with immunosuppressive phenotype as well as histopathological alterations including reduction of folliculogenesis and luteogenesis. Conclusions: OncoTherad was able to prevent histopathological lesions and reduce the angiogenesis involved in the ovarian carcinogenesis. EPO treatment decreased endostatin, which possibly had effects on angiogenic activity. However, EPO also modulated the OC microenvironment by reducing PD-1/PD-L1 and CTLA-4. The association of OncoTherad+EPO might have triggered a compensatory effect between the isolated treatments.

e16551 Background: This study detailed and characterized the mechanisms of action of OncoTherad nano-immunotherapy based on modulation of Toll-like Receptor 4 (TLR4) signaling pathway, CX3C chemokine receptor 1 (CX3CR1, a marker of T-cell differentiation) and immune checkpoints in patients with Bacillus Calmette-Guérin (BCG)-unresponsive high-grade non-muscle invasive bladder cancer. Methods: A single-center open-label (Paulinia Municipal Hospital, Brazil) and single-arm phase 1/2 study (Clinical Trial: RBR-6swqd2) was applied in 44 patients (30 male and 14 female) with BCG-unresponsive NMIBC (≥ 1 prior course of BCG therapy) submitted to OncoTherad immunotherapy for 24 months. Patient follow-ups were performed with systematic mapping biopsies of the bladder every 3 months for the first year and every 6 months thereafter for up to 2 years. Bladder biopsies of each patient (n = 44) were divided into 2 groups: Group 1 (initial biopsy, before OncoTherad treatment); and Group 2 (bladder biopsy after OncoTherad treatment). Subsequently, the samples were submitted to immunohistochemistry analysis: TLR4-mediated IFN-γ production signaling pathway (TRIF, TBK1, IRF-3), CX3CR1+CD8+ T-cells, immune checkpoints (PD-1/PD-L1 CTLA-4) and Regulatory T cells (FOXP3). Results: After 24-months follow-up, pathological complete response rate was 72.7% (95% CI) and recurrence-free survival of 21.4 months. Bladder samples from patients submitted to OncoTherad treatment (Group 2) showed intensified TLR4, TRIF, TBK1, IRF-3 and IFN-γ immunoreactivities when compared (p < 0.01) to initial biopsies (Group 1). Furthermore, as result of interferon signaling pathway (TRIF-dependent pathway) induction by OncoTherad, intensified CX3CR1 immunoreactivities (p < 0.01) were found in the Group 2. In contrast, PD-1/PD-L1 immunoreactivities were decreased (p < 0.01) in the Group 2 when compared to Group 1. No statistical differences were found between the two groups for FOXP3 and CTLA4. Conclusions: OncoTherad nano-immunotherapy led to activation of TLR4-mediated innate immune system, resulting in increased interferon signaling pathway, which was fundamental in the activation of antitumor CD8+ T-cells and decrease of PD-1/PD-L1 expression in the bladder microenvironment. These important findings are relevant concerning the treatment of patients with NMIBC presenting high-risk of progression that are BCG-unresponsive.

e17589 Background: The term ovarian carcinoma (OC) refers to a heterogeneous collection of five distinct diseases known as histotypes. While histotype-specific treatment is still a clinical challenge, well-characterized models are required for testing new therapies. OncoTherad is a nanoimmunotherapy developed by University of Campinas/Brazil, which exhibits antitumor properties. Erythropoietin (EPO) has cytoprotective effects including in the ovaries. We assessed whether a chemically-induced animal OC model was representative of human disease by evaluating which histotype it best represents. We evaluated both mutational and immunohistochemical (IHC) biomarkers routinely used for human OC and used the observed features to provide context in the evaluation of OncoTherad and EPO effects. Methods: Thirty-five Fischer rats were distributed into 5 groups: Control (Sham surgery); Cancer (7,12-dimethylbenzoanthracene – DMBA injection in the ovarian bursa, 1.25 mg/kg); OncoTherad (20mg/kg IP); EPO (8.4 µg/kg IP); and OncoTherad+EPO (same doses). Ovary specimens were formalin-fixed into paraffin-embedded donor blocks. After DNA extraction and tissue microarray construction, we assessed typical gene mutations directly by Sanger sequencing (Pik3ca, Ctnnb1, and Kras) or indirectly using IHC surrogates (Arid1a and p53). Finally, we examined biomarkers typical of different OC histotypes (Wt1, Pr, Hnf1β) as well as lymphocyte density (CD3) by IHC. Results: The results were consistent across the cancer-induced animals. The majority of abnormal epithelial cells were Wt1+, Pr-, and Hnf1b-. Therefore, our rat model of DMBA-induced ovarian cancer was most likely serous type ovarian carcinoma, in agreement with the histopathological analysis. The ovarian lesions were molecularly similar to low-grade serous ovarian carcinoma as abnormal pattern of p53 staining was rarely observed. Loss of immunoreactivity for Arid1a protein was seen in some abnormal epithelium. However, the interpretability of mutation surrogates in rat tissues may not always be consistent with IHC analysis systems applied for human tissues. Furthermore, DNA sequencing did not reveal driver mutations in any of the sampled specimens. The treatments, especially OncoTherad+EPO, increased the number of CD3 positive immune cells. After EPO treatment, the tumor and abnormal areas showed a higher number of CD3+ lymphocytes than the normal regions; following a previous work, this could be due to substantial presence of Foxp3 positive cells. Conclusions: The features analyzed favored a low-grade serous carcinoma model in which treatments with OncoTherad and EPO showed immunomodulatory properties related to the reduction of ovarian lesions seen in previous work. The overall data highlight the importance of further characterizations of animal models to provide a complete and specific panel for testing new drugs.