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      Metastatic role of mammalian target of rapamycin signaling activation by chemoradiotherapy in advanced rectal cancer

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          Abstract

          Postoperative distant metastasis dramatically affects rectal cancer patients who have undergone neoadjuvant chemoradiotherapy (NACRT). Here, we clarified the association between NACRT‐mediated mammalian target of rapamycin (mTOR) signaling pathway activation and rectal cancer metastatic potential. We performed immunohistochemistry for phosphorylated mTOR (p‐mTOR) and phosphorylated S6 (p‐S6) on surgical specimen blocks from 98 rectal cancer patients after NACRT (cohort 1) and 80 colorectal cancer patients without NACRT (cohort 2). In addition, we investigated the association between mTOR pathway activity, affected by irradiation, and the migration ability of colorectal cancer cells in vitro. Based on the results of the clinical study, p‐mTOR was significantly overexpressed in cohort 1 (with NACRT) as compared to levels in cohort 2 (without NACRT) ( P < .001). High p‐mTOR and p‐S6 levels correlated with the development of distant metastasis only in cohort 1. Specifically, high p‐S6 expression (HR 4.51, P = .002) and high pathological T‐stage (HR 3.73, P = .020) after NACRT were independent predictors of the development of distant metastasis. In vitro, p‐S6 levels and migration ability increased after irradiation in SW480 cells ( TP53 mutation‐type) but decreased in LoVo cells ( TP53 wild‐type), suggesting that irradiation modulates mTOR signaling and migration through cell type‐dependent mechanisms. We next assessed the expression level of p53 by immunostaining in cohort 1 and demonstrated that p‐S6 was overexpressed in samples with high p53 expression as compared to levels in samples with low p53 expression ( P = .008). In conclusion, p‐S6 levels after NACRT correlate with postoperative distant metastasis in rectal cancer patients, suggesting that chemoradiotherapy might modulate the mTOR signaling pathway, promoting metastasis.

          Abstract

          The postoperative distant recurrence is critical in rectal cancer patients who have received neoadjuvant chemoradiotherapy (NACRT). We investigated NACRT‐mediated mTOR activation and metastatic potential of rectal cancer, identifying p‐S6 expression as a NACRT predictor of postoperative distant metastasis in rectal cancer patients, suggesting that chemoradiotherapy may modulate the mTOR signaling pathway to promote metastasis.

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          Preoperative versus postoperative chemoradiotherapy for locally advanced rectal cancer: results of the German CAO/ARO/AIO-94 randomized phase III trial after a median follow-up of 11 years.

          Preoperative chemoradiotherapy (CRT) has been established as standard treatment for locally advanced rectal cancer after first results of the CAO/ARO/AIO-94 [Working Group of Surgical Oncology/Working Group of Radiation Oncology/Working Group of Medical Oncology of the Germany Cancer Society] trial, published in 2004, showed an improved local control rate. However, after a median follow-up of 46 months, no survival benefit could be shown. Here, we report long-term results with a median follow-up of 134 months. A total of 823 patients with stage II to III rectal cancer were randomly assigned to preoperative CRT with fluorouracil (FU), total mesorectal excision surgery, and adjuvant FU chemotherapy, or the same schedule of CRT used postoperatively. The study was designed to have 80% power to detect a difference of 10% in 5-year overall survival as the primary end point. Secondary end points included the cumulative incidence of local and distant relapses and disease-free survival. Of 799 eligible patients, 404 were randomly assigned to preoperative and 395 to postoperative CRT. According to intention-to-treat analysis, overall survival at 10 years was 59.6% in the preoperative arm and 59.9% in the postoperative arm (P = .85). The 10-year cumulative incidence of local relapse was 7.1% and 10.1% in the pre- and postoperative arms, respectively (P = .048). No significant differences were detected for 10-year cumulative incidence of distant metastases (29.8% and 29.6%; P = .9) and disease-free survival. There is a persisting significant improvement of pre- versus postoperative CRT on local control; however, there was no effect on overall survival. Integrating more effective systemic treatment into the multimodal therapy has been adopted in the CAO/ARO/AIO-04 trial to possibly reduce distant metastases and improve survival.
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            Deregulation of the PI3K and KRAS signaling pathways in human cancer cells determines their response to everolimus.

            Personalized cancer medicine is based on the concept that targeted therapies are effective on subsets of patients whose tumors carry specific molecular alterations. Several mammalian target of rapamycin (mTOR) inhibitors are in preclinical or clinical trials for cancers, but the molecular basis of sensitivity or resistance to these inhibitors among patients is largely unknown. Here we have identified oncogenic variants of phosphoinositide-3-kinase, catalytic, alpha polypeptide (PIK3CA) and KRAS as determinants of response to the mTOR inhibitor everolimus. Human cancer cells carrying alterations in the PI3K pathway were responsive to everolimus, both in vitro and in vivo, except when KRAS mutations occurred concomitantly or were exogenously introduced. In human cancer cells with mutations in both PIK3CA and KRAS, genetic ablation of mutant KRAS reinstated response to the drug. Consistent with these data, PIK3CA mutant cells, but not KRAS mutant cells, displayed everolimus-sensitive translation. Importantly, in a cohort of metastatic cancer patients, the presence of oncogenic KRAS mutations was associated with lack of benefit after everolimus therapy. Thus, our results demonstrate that alterations in the KRAS and PIK3CA genes may represent biomarkers to optimize treatment of patients with mTOR inhibitors.
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              Abscopal, immunological effects of radiotherapy: Narrowing the gap between clinical and preclinical experiences.

              Radiotherapy-despite being a local therapy that meanwhile is characterized by an impressively high degree of spatial accuracy-can stimulate systemic phenomena which occasionally lead to regression and rejection of non-irradiated, distant tumor lesions. These abscopal effects of local irradiation have been observed in sporadic clinical case reports since the beginning of the 20th century, and extensive preclinical work has contributed to identify systemic anti-tumor immune responses as the underlying driving forces. Although abscopal tumor regression still remains a rare event in the radiotherapeutic routine, increasing numbers of cases are being reported, particularly since the clinical implementation of immune checkpoint inhibiting agents. Accordingly, interests to systematically exploit the therapeutic potential of radiotherapy-stimulated systemic responses are constantly growing. The present review briefly delineates the history of radiotherapy-induced abscopal effects and the activation of systemic anti-tumor immune responses by local irradiation. We discuss preclinical and clinical reports with specific focus on the corresponding controversies, and we propose issues that should be addressed in the future in order to narrow the gap between preclinical knowledge and clinical experiences.
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                Author and article information

                Contributors
                tori.shior@gmail.com
                Journal
                Cancer Sci
                Cancer Sci
                10.1111/(ISSN)1349-7006
                CAS
                Cancer Science
                John Wiley and Sons Inc. (Hoboken )
                1347-9032
                1349-7006
                22 February 2020
                April 2020
                : 111
                : 4 ( doiID: 10.1111/cas.v111.4 )
                : 1291-1302
                Affiliations
                [ 1 ] Department of Surgical Oncology The University of Tokyo Tokyo Japan
                [ 2 ] Department of Pathology Faculty of Medicine University of Tokyo Tokyo Japan
                Author notes
                [*] [* ] Correspondence

                Hiroshi Shiratori, Department of Surgical Oncology, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku, Tokyo, 113‐8655, Japan.

                Email: tori.shior@ 123456gmail.com

                Author information
                https://orcid.org/0000-0001-7404-7926
                Article
                CAS14332
                10.1111/cas.14332
                7156826
                31997546
                df964cb4-7aa6-4e67-be96-8e97d935aa85
                © 2020 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

                This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

                History
                : 18 September 2019
                : 06 January 2020
                : 07 January 2020
                Page count
                Figures: 7, Tables: 3, Pages: 12, Words: 6784
                Funding
                Funded by: Japan Society for the Promotion of Science , open-funder-registry 10.13039/501100001691;
                Award ID: 17K10620
                Award ID: 17K 10621
                Award ID: 17K10623
                Award ID: 18K07194
                Award ID: 19K09114
                Award ID: 19K09115
                Funded by: Japan Agency for Medical Research and Development , open-funder-registry 10.13039/100009619;
                Award ID: JP 19cm0106502
                Categories
                Original Article
                Original Articles
                Clinical Research
                Custom metadata
                2.0
                April 2020
                Converter:WILEY_ML3GV2_TO_JATSPMC version:5.8.0 mode:remove_FC converted:15.04.2020

                Oncology & Radiotherapy
                chemoradiotherapy,distant metastasis,epithelial–mesenchymal transition,mtor,rectal cancer

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