Healthcare providers are vulnerable to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) because of their close proximity to patients with coronavirus disease 2019. SARS-CoV-2 is mainly transmitted via direct and indirect contact with respiratory droplets, and its airborne transmission has also been identified. However, evidence for environmental factors is scarce, and evidence-based measures to minimize the risk of infection in clinical settings are insufficient. Using computational fluid dynamics, we simulated exhalation of large and small aerosol particles by patients in an otolaryngology examination room, where medical procedures require the removal of a face mask. The effects of coughing were analyzed, as well as those of humidity as a controllable environmental factor and of a suction device as an effective control method. Our results show that a suction device can minimize aerosol exposure of healthcare workers by efficiently removing both large (11.6–98.2%) and small (39.3–99.9%) aerosol particles. However, for coughing patients, the removal efficiency varies inversely with the particle size, and the humidity notably affects the aerosol behavior, indicating the need for countermeasures against smaller aerosols. Overall, these results highlight the potential and limitation of using a suction device to protect against SARS-CoV-2 and future respiratory infections.

The interaction between prostate cancer cells and osteoblasts is essential for the development of bone metastasis. Previously, novel androgen receptor axis-targeted agents (ARATs) were approved for metastatic castration-naïve and non-metastatic castration-resistant prostate cancer (CRPC); both of which are pivotal for investigating the association between the bone microenvironment and tumors. The present study established a novel in vitro 3D microenvironment model that simulated the bone microenvironment of CRPC, and evaluated the drug susceptibility of ARATs and the efficacy of the combination of abiraterone and dutasteride. Green fluorescent protein-transferred C4-2 cells (a CRPC cell line) and red fluorescent protein-transferred human osteoblasts differentiated from human mesenchymal stem cells were co-cultured in chitosan nanofiber matrix-coated culture plates to simulate the 3D scaffold of the bone microenvironment. The growth of C4-2 was quantified using live-cell imaging and the Cell3 iMager duos analysis system. The growth of C4-2 colonies were quantified for a maximum of 30 days. The expression of TGF-β increased and promoted EMT in C4-2 cells co-cultured with osteoblasts, indicating resistance to ARATs. The IC 50 of each drug and the combination effect of abiraterone and dutasteride were evaluated using this model. Combination treatment with abiraterone and dutasteride synergistically inhibited the growth of C2-4 colonies compared with individual investigational agents. This could be attributed to the reduction of 3-keto-5α-abiraterone, an androgen receptor agonist. The bone microenvironment model of the present study is unique and useful for evaluating new drug susceptibility testing in prostate cancer cells. This model may help to reveal the unknown mechanisms underlying micro- to clinical bone metastasis in prostate cancer.

BACKGROUND: The interaction between prostate cancer cells and osteoblast is essential for the development of bone metastasis. Recently, novel androgen receptor signal inhibitors (ARSi) have been approved for metastatic castration naïve (mCNPC), or non-metastatic castration resistant prostate cancer (nmCRPC), both of which should be pivotal to investigate the association between bone microenvironment and tumor. We established a novel 3D in vitro culture method reflecting bone microenvironment and evaluated the drug susceptibility of ARSi including enzalutamide, apalutamide, darolutamide, and abiraterone (Abi) with/without dutasteride (Duta). METHODS: GFP-transferred C4-2 (CRPC cell line) and RFP-transferred human osteoblast differentiated from human-mesenchymal stem cell was co-cultured in chitosan nanofiber, a mimicry of 3D scaffold of bone microenvironment, coated culture plate (Cosmo bio Co., LTD). The growth of C4-2 cell was quantified using live-cell imaging and analysis system, Cell3 iMager duos (SCREEN). Abi metabolites including delta-4 abiraterone (D4A) and 3-keto-5-alfa abiraterone in C4-2 cells were measured by ESI-TOF-MS method. RESULTS: We could non-invasively quantify the sustained growth of C4-2 cells at maximum of 30 days. IC50 of each drugs and combination effect of Abi and Duta was evaluated using this model. Combination treatment synergistically inhibited the growth of C2-4 cells compared with each drug alone. D4A, the strongest anti-proliferative metabolite of Abi under the CRPC-specific backdoor pathway, was detected from the treated C4-2 cell. These results were coincided with the effective cases of pharmacokinetics of Abi metabolites in our ongoing phase II clinical trial of combination therapy of Abi with Duta for CRPC (UMIN000027795). Furthermore, combination of abiraterone and dutasteride was most potent cell growth inhibitor than other ARis tested in this model. This model is applying for international patent (C12N 5/09). CONCLUSIONS: Our bone microenvironment model is unique and useful to evaluate the new drug susceptibility testing in prostate cancer cells. This model may help in disclose unknown mechanisms from micro- to clinical bone metastasis in prostate cancer. Citation Format: Masahiro Samoto, Hiroaki Matsumoto, Hiroshi Hirata, Sho Ozawa, Junichi Mori, Ryo Inoue, Seiji Yano, Yoshiaki Yamamoto, Hideyasu Matsuyama. Novel bone microenvironment model of prostate cancer with chitosan fiber matrix and osteoblast in 3D culture [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 321.

516 Background: Radical cystectomy is still the standard treatment for muscle-invasive bladder cancer (MIBC), while the patients with MIBC are not always appropriate candidates due to multiple comorbidities. We establish novel treatment strategy by trimodal treatment. Methods: The regimen was gemcitabine 300 mg/m2, and cisplatin 30mg/m2 in day 1 and concomitant irradiation 2Gy/Fr, 5 fraction per week. Irradiation was administered to whole pelvis up to 30Gy, then boost to true pelvis until total 48Gy to 54Gy. Extensive transurethral resection (TURBT) was performed and we confirmed pathological stage ≥T2. TURBT was also performed after chemoradiotherapy to evaluate the pathological response to treatment. This study was approved in our institutional review board (ID: H23-89) and the information was opened on UMIN (ID: UMIN000006363). We analyzed their treatment efficacy and survival. Results: The patients were 29 men and 9 women, median age was 76.5 y.o. and median follow up was 23 months (1 - 112). Clinical stage T2, T3, T4, N1 and N2 were 23, 10, 5, 4, 2 cases, respectively. The 2- and 5-year metastatic-free survival (MFS), bladder-recurrence free survival (bRFS), cancer-specific survival (CSS), and overall survival (OS) rates after treatment were 91.7 and 84.0%, 59.7 and 42.6%, 87.3 and 87.3%, and 87.3 and 81.8%, respectively. Salvage cystectomy was performed 3 patients and they were still alive. CR rate was 78.9% and overall response rate was 92.1%. cT stage and valiant histology was not associated with treatment response. The patients achieved CR had significant good prognosis in CSS (p=0.0149) and OS (p=0.0149) compared with non-responders. In cox hazard model, CR achievement was significant prognostic factors for OS (p =0.0015, HR 6.804e+26, 95% CI 56.94-1.631e+86). Patients were able to receive 3 to 5 cycle GC radiation and any grade 3 or more adverse event was 7 (18.4%) cases. no treatment related death was recorded. Conclusions: In selected patients, GC radiation for MIBC may provide good oncological outcomes as bladder preservation strategy.

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