A case of gastrointestinal stromal tumor with synchronous liver metastases showing long-term disease control by imatinib

　Radical surgery is the primary treatment for gastrointestinal stromal tumor (GIST), so that unrsectable GIST has been considered a fatal disease, and the median duration of survival for patients with an unresectable GIST before the era of molecular targeted therapy has been about 18 months. Since the recent development of agents for molecular targeted therapy, including imatinib mesylate, the prognosis of unrsectable GIST has been dramatically improved. The B2222 trial reported that a median time to progression and a median overall survival for advanced GIST treated with imatinib of 24 months and 57 months, respectively. We recently experienced a case of gastrointestinal stromal tumor with synchronous liver metastases maintained in whom the disease was controlled for 4 years by imatinib. The patient is 37-year-old man and he took imatinib mesylate at 400mg/day with no adverse events. Both primary and metastases lesions responded well to imatinib treatment, and this efficacy has endured for 4 years, such that surgical intervention is now considered possible. While GIST is a relatively rare disease and clinical evidence is still poor, we document our considerations for the therapy in this case as well as the results

A successful rechallenge with cetuximab for a case with metastatic rectal cancer

　A 55-year-old man who had been diagnosed with rectal cancer with multiple liver metastases and lymph node metastases on colonoscopy and computed tomography (CT) was referred to Okayama University Hospital for treatment. Based on the diagnosis of non-curative rectal cancer, we planned to perform systematic chemotherapy after surgical resection. We performed a low anterior resection of a 36×35 mm upper rectal moderately differentiated adenocarcinoma with wil-type KRAS. After the resection, a FOLFIRI regimen with cetuximab was given as the first-line chemotherapy. Although metastatic lesions in the liver showed shrinkage, we decided to switch regimens because of intolerable adverse events. A modified FOLFOX6 regimen with bevacizumab was administered as the second-line treatment. There were no signs of disease progression until eight months later, when positron emission tomography (PET)/CT scans revealed that the new metastatic lesions appeared. As the third-line treatment, an irinotecan with cetuximab regimen was administered, leading to a good response for over 12 months. 　We experienced a successful rechallenge with cetuximab for a case with metastatic rectal cancer. For patients with wild-type KRAS colorectal cancer, rechallenge with cetuximab-based chemotherapy can be an effective therapeutic option

Radiosensitization by telomerase-dependent oncolytic adenovirus

DNA修復機能阻害は放射線感受性を増強させるため，DNA修復に関与する因子の阻害剤は放射線増感剤となり得る．我々の開発したテロメラーゼ依存的腫瘍融解アデノウイルス製剤OBP-301（テロメライシン）は，アデノウイルスE1B55kDaタンパクを介して細胞のDNA修復に重要な役割を果たすMRN複合体（Mre11，Rad50，NBS1）を分解する機能を有する．このMRN複合体の分解によりATM（ataxia-telangiectasia mutated）の活性化が抑制され結果的にDNA修復機構が阻害される．我々はOBP-301と放射線との併用が強力な相乗効果を生み出すことをマウスの皮下腫瘍モデルおよび食道癌同所性モデルにおいて証明した．これらの結果はOBP-301が将来有望な放射線増感剤となり得ることだけでなく，E1B55kDaタンパクを産生する腫瘍融解アデノウイルス製剤と放射線との併用が悪性腫瘍に対する有力な治療戦略となり得ることを示す

A case of metastatic cecal cancer with mutation in the BRAF oncogene and poor survival

　A 79-year-old woman visited a previous hospital with a complaint of general fatigue. The patient was diagnosed with cecal cancer with multiple liver metastases and lymph node metastases on colonoscopy, abdominal ultrasonography and CT scan, and was referred to our division for treatment. Based on the diagnosis of non-curative colonic cancer, we planned to perform systematic chemotherapy after local surgical treatment. We performed an ileocecal resection, and the specimen showed poorly differentiated adenocarcinoma with mutation in the BRAF oncogene. After the surgical treatment, the tumor grew rapidly and the patient died from cancer on the 19th postoperative day without having the opportunity to undergo chemotherapy. 　Multiple genetic and epigenetic alterations in oncogenes and tumor suppressor genes are involved in the process of colorectal carcinogenesis. Some of the alterations have been identified as predictive and prognostic biomarkers. A mutation in the BRAF oncogene was reported to be associated with a very unfavorable prognosis in colorectal cancers. Some of the cases with rapid progression are suggested to have the BRAF oncogene mutation. According to our experience, chemotherapy before surgical treatment might improve the prognosis of cases with the BRAF mutation

A Genetically Engineered Oncolytic Adenovirus Decoys and Lethally Traps Quiescent Cancer Stem-like Cells in S/G(2)/M Phases

Purpose: Because chemoradiotherapy selectively targets proliferating cancer cells, quiescent cancer stem-like cells are resistant. Mobilization of the cell cycle in quiescent leukemia stem cells sensitizes them to cell death signals. However, it is unclear that mobilization of the cell cycle can eliminate quiescent cancer stem-like cells in solid cancers. Thus, we explored the use of a genetically-engineered telomerase-specific oncolytic adenovirus, OBP-301, to mobilize the cell cycle and kill quiescent cancer stem-like cells. Experimental Design: We established CD133(+) cancer stem-like cells from human gastric cancer MKN45 and MKN7 cells. We investigated the efficacy of OBP-301 against quiescent cancer stem-like cells. We visualized the treatment dynamics of OBP-301 killing of quiescent cancer stem-like cells in dormant tumor spheres and xenografts using a fluorescent ubiquitination cell-cycle indicator (FUCCI). Results: CD133(+) gastric cancer cells had stemness properties. OBP-301 efficiently killed CD133(+) cancer stem-like cells resistant to chemoradiotherapy. OBP-301 induced cell-cycle mobilization from G(0)-G(1) to S/G(2)/M phases and subsequent cell death in quiescent CD133(+) cancer stem-like cells by mobilizing cell-cycle-related proteins. FUCCI enabled visualization of quiescent CD133(+) cancer stem-like cells and proliferating CD133(-) non-cancer stem-like cells. Three-dimensional visualization of the cell-cycle behavior in tumor spheres showed that CD133(+) cancer stem-like cells maintained stemness by remaining in G(0)-G(1) phase. We showed that OBP-301 mobilized quiescent cancer stem-like cells in tumor spheres and xenografts into S/G(2)/M phases where they lost viability and cancer stem-like cell properties and became chemosensitive. Conclusion: Oncolytic adenoviralinfection is an effective mechanism of cancer cell killing in solid cancer and can be a new therapeutic paradigm to eliminate quiescent cancer stem-like cells

Identification of Physiologically Active Substances as Novel Ligands for MRGPRD

Mas-related G-protein coupled receptor member D (MRGPRD) is a G protein-coupled receptor (GPCR) which belongs to the Mas-related GPCRs expressed in the dorsal root ganglia (DRG). In this study, we investigated two novel ligands in addition to beta-alanine: (1) beta-aminoisobutyric acid, a physiologically active substance, with which possible relation to tumors has been seen together with beta-alanine; (2) diethylstilbestrol, a synthetic estrogen hormone. In addition to the novel ligands, we found that transfection of MRGPRD leads fibroblast cells to form spheroids, which would be related to oncogenicity. To understand the MRGPRD novel character, oncogenicity, a large chemical library was screened in order to obtain MRGPRD antagonists to utilize in exploring the character. The antagonist in turn inhibited the spheroid proliferation that is dependent on MRGPRD signaling as well as MRGPRD signals activated by beta-alanine. The antagonist, a small-molecule compound we found in this study, is a potential anticancer agent

Dual Programmed Cell Death Pathways Induced by p53 Transactivation Overcome Resistance to Oncolytic Adenovirus in Human Osteosarcoma Cells

Tumor suppressor p53 is a multifunctional transcription factor that regulates diverse cell fates, including apoptosis and autophagy in tumor biology. p53 overexpression enhances the antitumor activity of oncolytic adenoviruses; however, the molecular mechanism of this occurrence remains unclear. We previously developed a tumor-specific replication-competent oncolytic adenovirus, OBP-301, that kills human osteosarcoma cells, but some human osteosarcoma cells were OBP-301-resistant. In this study, we investigated the antitumor activity of a p53-expressing oncolytic adenovirus, OBP-702, and the molecular mechanism of the p53-mediated cell death pathway in OBP-301-resistant human osteosarcoma cells. The cytopathic activity of OBP-702 was examined in OBP-301-sensitive (U2OS and HOS) and OBP-301-resistant (SaOS-2 and MNNG/HOS) human osteosarcoma cells. The molecular mechanism in the OBP-702-mediated induction of two cell death pathways, apoptosis and autophagy, was investigated in OBP-301-resistant osteosarcoma cells. The antitumor effect of OBP-702 was further assessed using an orthotopic OBP-301-resistant MNNG/HOS osteosarcoma xenograft tumor model. OBP-702 suppressed the viability of OBP-301-sensitive and -resistant osteosarcoma cells more efficiently than OBP-301 or a replication-deficient p53-expressing adenovirus (Ad-p53). OBP-702 induced more profound apoptosis and autophagy when compared with OBP-301 or Ad-p53. E1A-mediated miR-93/106b upregulation induced p21 suppression, leading to p53-mediated apoptosis and autophagy in OBP-702-infected cells. p53 overexpression enhanced adenovirus-mediated autophagy through activation of damage-regulated autophagy modulator (DRAM). Moreover, OBP-702 suppressed tumor growth in an orthotopic OBP-301-resistant MNNG/HOS xenograft tumor model. These results suggest that OBP-702-mediated p53 transactivation is a promising antitumor strategy to induce dual apoptotic and autophagic cell death pathways via regulation of miRNA and DRAM in human osteosarcoma cells. Mol Cancer Ther; 12(3); 314-25