A potential new therapeutic option for the treatment of nonmuscle invasive bladder cancer: Combination of intravesical oncotherad immunotherapy and platelet rich plasma (PRP).

Abstract

461 Background: Effective intravesical therapies remain lacking for non-muscle invasive bladder cancer (NMIBC) when Bacillus Calmette-Guerin fails. OncoTherad is a nanostructured inorganic phosphate complex associated with glycosidic protein, developed by the University of Campinas/Brazil, which triggers immunomodulatory and antitumor activities. Previous studies have shown that Platelet Rich Plasma (PRP) acts on immune activation and exerts antitumor effects. This study characterized the effects of the OncoTherad associated with PRP in the treatment of NMIBC chemically induced in mice and the modulation promoted in the Toll-like receptors (TLRs) signaling pathway. Methods: Forty-two C57BL/6J mice were divided into groups: Control; Cancer (N-ethyl-N-nitrosourea carcinogen, 50 mg/ml); PRP (0.1 ml); OncoTherad (20 mg/ml); OncoTherad+PRP 10 mg/ml and OncoTherad+PRP 20 mg/ml. The intravesical doses (0.1 ml) were instilled once a week for 6 weeks after induction. Results: The NMIBC induction decreases (p<0.05) body weight, although after treatments the body weight was recovered similarly to the healthy mice. The treatments did not significantly alter the biochemical patterns of the urine and food and water consumption. There was no acute toxicity or kidney damage, and the presence of hydroureter was variable. The urinary bladders of mice treated with Oncotherad associated or not with PRP showed hyperemia associated with the inflammatory condition. The thickening of the urinary bladder wall in the Cancer group was more evident than in the treated groups, in which there were bladders without thickening or macroscopic lesions. Flat carcinoma in situ (pTis) was present in 100% of the mice in the Cancer group and the intensity of immunoreactivities for TLR2, IL-6, TLR4, and IRF-3 was significantly weaker in comparison with the Control, indicating suppression of the immune system in the tumor microenvironment. When treated intravesically with PRP only, mice showed 28.6% of tumor progression inhibition rate; with OncoTherad 85.7% and with OncoTherad+PRP 10 mg/ml or 20 mg/ml 71.4%. Intravesical treatments led to distinct activation of TLRs 2 and 4-mediated innate immune system in the interleukins (MyD88-dependent) and interferons (TRIF-dependent) signaling pathways. The combined treatment of OncoTherad+PRP increased (p<0.05) the percentage of positive TLR4 urothelial cells and the intensity of immunoreaction for TLR4 compared to the isolated treatments and the immunoreactivities of NF-kB, IL-6, TLR4, IRF-3, and IFN-γ in comparison to the Cancer. Conclusions: Intravesical treatment with OncoTherad plus PRP promoted significant inhibition of tumor progression, possibly due to immunomodulatory activity involving the TLR pathway. This association can constitute a therapeutic strategy for refractory NMIBC patients.