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Gastric cancer is highly malignant and recalcitrant to first line chemotherapies that include 5-fluorouracil (5-FU). Cancer cells are addicted to methionine for their proliferation and survival. Methionine addiction of cancer is known as the Hoffman effect. Methionine restriction with recombinant methioninase (rMETase) has been shown to selectively starve cancer cells and has shown synergy with cytotoxic chemotherapy including 5-FU. The present study aimed to investigate the efficacy of rMETase alone and the combination with 5-FU on poorly differentiated human gastric cancer cell lines (MKN45, NUGC3, and NUGC4) in vitro and vivo. rMETase suppressed the tumor growth of 3 kinds of poorly differentiated gastric cancer cells in vitro. The fluorescence ubiquitination-based cell cycle indicator (FUCCI) demonstrated cancer cells treated with rMETase were selectively trapped in the S/G

The purpose of the present study was to clarify clinical outcomes of elderly patients with soft tissue sarcoma who underwent surgery neither with neoadjuvant nor adjuvant chemotherapy. The median follow-up period was 46.3 (range 6.7-99.0) months. All patients underwent surgical resections. R0 margins were achieved in 24 cases (92.3%) and R1 margins in 2 cases (7.7%). The 1-, 2-, and 5-year sarcoma-specific survival (SSS) rates were 92.3%, 88.5%, and 83.8%, respectively. Multivariate analysis showed no significant risk factors for SSS. No significant relationship of histological grades and local recurrences (P = .56) or distant metastases (P = .54) was shown. In the current study, we observed a comparable survival ratio, despite no neoadjuvant or adjuvant chemotherapies performed. Tumor resections with adequate margins might, at least in part, have contributed to the decent survival ratio regardless of histological grade. Twenty-six consecutive patients aged ≥ 70 years, who underwent surgical resections of soft tissue sarcoma between January 2013 and December 2019, were included. SSS were analyzed by the Kaplan-Meier method, and the relationships between SSS and clinical parameters were evaluated by Cox proportional hazards analysis.

Background A mouse model of metastatic osteosarcoma is imperative to identify effective agents for metastatic osteosarcoma, which is a recalcitrant disease. In the present study, we established osteosarcoma patient-derived cells (OS-PDCs) and transfected them with green fluorescent protein (GFP). Materials and methods The OS-PDCs were transfected with GFP-lentivirus. GFP-expressing OS-PDCs (2.0×105) were then injected into the tibia of nude mice to establish the patient-derived orthotopic cell (PDOC) model (n=3). Six weeks after injection, the primary tumor and each organ were resected and imaged. Results Primary orthotopic tumors were established in two out of three mice. The GFP-expressing OS-PDCs in the PDOC model were visualized. Multiple GFP-expressing lung metastases were detected in one of the two mice with primary tumor. Conclusion The present study proves the concept that a GFP-expressing PDOC model can mimic clinical lung-metastatic osteosarcoma. This model can serve as a paradigm to screen for effective drugs for osteosarcoma lung metastasis.

Since methotrexate (MTX) resistance of osteosarcoma is a frequent cause of poor prognosis, new treatment strategies are needed to overcome this recalcitrant problem. The present study investigated if MTX resistance increased malignancy of osteosarcoma cells and its possible mechanism, via histone-H3 lysine-methylation status. We also propose a new therapeutic strategy for MTX resistant osteosarcoma. MTX resistant 143B osteosarcoma cells (143B-MTXR) were established from 143B parental osteosarcoma cells (143B-P) by culturing the cells with increasing concentrations of MTX stepwise (0.04 μM to 100 μM) for 12 months. The degree of malignancy of the isogenic pair of 143B-MTXR and 143B-P cells was compared by testing clonogenic capacity in cell culture, on both plastic and soft agar. Malignancy was also compared by tumor growth in orthotopic xenograft mouse models by implantation of 2.5 × 105 cells in the tibia of nude mice. Histone-H3 lysine-methylation status was determined by Western immunoblotting. 143B-MTXR and 143B-P cells were also tested for methionine addiction by sensitivity to recombinant methioninase (rMETase). Welch’s t-test was performed to statistically evaluate results and a probability value ≤ 0.05 was defined as statistically-significant difference. The mouse studies were approved by Institutional Animal Care and Use Committee of AntiCancer Inc. After 12 months selection in increasing concentrations of MTX, we isolated 143B-MTXR cells, which had an MTX IC50 of 384 μM compared to 143B-P cells, which had an IC50 of 0.27 μM, demonstrating that the 143B-MTXR cells acquired a 1422-fold resistance to MTX. In cell culture, 143B-MTXR cells had reduced clonogenic capacity on plastic and in soft agar (P < 0.01), indicating reduction in malignancy. In orthotopic xenograft nude-mouse studies, 143B-MTXR cells formed much smaller tumors than 143B-P cells (P < 0.01), further indicating that 143B-MTXR cells lost malignancy. 143B-MTXR cells showed an increase of histone H3K9me3 (P = 0.01), H3K27me3 (P < 0.01), and H3K79me3 (P < 0.01) methylation, which may account in part for their decreased malignancy. However, there was no difference in methylation of H3K4me3 (P = 0.12) or H3K36me3 (P = 0.29). The 143B-MTXR cells had an IC50 of 0.358 U/ml for rMETase, similar to an IC50 of 0.38 U/ml for 143B-P cells, indicating the 143B-MTXR cells did not lose their methionine addiction. The increase in histone H3K9me3, H3K27me3, and H3K79me3 shown in the present study in 143B-MTXR cells suggested potential biomarkers of methotrexate-resistance. MTX resistant osteosarcoma may be treated by methionine restriction with rMETase, as the MTX-resistant osteosarcoma cells are highly methionine addicted. Citation Format: Yusuke Aoki, Yasunori Tome, Hiromichi Oshiro, Ryo Katsuki, Kohei Mizuta, Kotaro Nishida, Robert M. Hoffman. Alteration of malignancy and histone-H3 lysine-methylation status in osteosarcoma cells which acquire methotrexate resistance in vitro. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3896.

Our laboratory pioneered the patient-derived orthotopic xenograft (PDOX) model. An important goal of PDOX-model development is facile visualization of metastasis in live mice. In the present report we evaluated tumor growth and metastasis in pancreatic cancer PDOX NOG [Non-obese diabetes (NOD)/Scid/IL2RγA patient-derived pancreatic cancer was initially implanted in transgenic RFP-expressing nude mice. Then, tumor fragments, which acquired RFP expressing stroma while growing in RFP-expressing nude mice were orthotopically implanted in nude and NOG mice. The primary pancreatic tumor and metastasis were observed 8 weeks after implantation.Lymph-node metastases expressing red fluorescence were detected only in NOG mice. Significantly faster growth of primary pancreatic tumors and a higher incidence of lymph-node metastasis occurred in NOG mice compared to nude mice.RFP-expressing tumor stroma, which traffics together with cancer cells to lymph nodes, is useful to observe tumor behavior, such as lymph-node metastasis in a PDOX NOG-mouse model which can be used for evaluation of novel anti-metastatic agents, as well as personalized therapy to identify effective drugs.

Background/aim Brain metastases are found in approximately 30% of patients with epidermal-growth-factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). We compared the efficacy of two EGFR-tyrosine kinase inhibitors (TKIs), erlotinib and osimertinib on a PC-9-GFP EGFR mutant NSCLC growing in the brain of nude mice. Materials and methods The brain metastasis models were randomized into five groups and treated for 15 days: Control; 5 mg/kg erlotinib; 50 mg/kg erlotinib; 0.5 mg/kg osimertinib; 5 mg/kg osimertinib. Tumor volume was evaluated by non-invasive fluorescence imaging. Results Only 5 mg/kg osimertinib, a low-dose compared to the clinically-equivalent dose, showed significant tumor regression compared to the control. Conclusion This study strongly supports the high activity of osimertinib for intracranial lesions of EGFR-mutant NSCLC.

Cancers are methionine (MET) and methylation addicted, causing them to be highly sensitive to MET restriction. The present study determined the efficacy of restricting MET with oral-recombinant methioninase (o-rMETase) and the DNA methylation inhibitor, azacitidine (AZA) on a chemotherapy-resistant osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model. The osteosarcoma PDOX models were randomized into five treatment groups of six mice: control; doxorubicin (DOX) alone; AZA alone; o-rMETase alone; o-rMETase-AZA combination. Tumor size and body weight were measured during the 14 days of treatment. We found that tumor growth was arrested only by the o-rMETase–AZA combination treatment, as tumors with this treatment exhibited tumor necrosis with degenerative change. This study suggests that o-rMETase-AZA combination has clinical potential for patients with chemoresistant osteosarcoma.

Background/aim Gemcitabine is standard first-line treatment for patients with advanced pancreatic cancer, however the efficacy is limited. Although acquired drug resistance and side-effects are known to limit efficacy, opposite effects of a drug, which enhance the malignancy of treated cancer, have been observed but are not well understood. The aim of the present study was to determine whether gemcitabine has such opposite effects on the BxPC-3 human pancreatic cancer cell line expressing green fluorescent protein (BxPC-3-GFP) in an orthotopic mouse model. Materials and methods BxPC-3-GFP tumors grown subcutaneously in nude mice were harvested. Tumor fragments were orthotopically implanted in the tail of the pancreas of nude mice using the technique of surgical orthotopic implantation. The BxPC-3-GFP orthotopic models were divided randomly into three groups: Group 1: untreated control; Group 2: low-dose gemcitabine (weekly intraperitoneal injection at 25 mg/kg for 6 weeks); Group 3: high-dose gemcitabine (weekly intraperitoneal injection at 125 mg/kg for 6 weeks). Each group comprised eight mice. Tumor size, fluorescent area of metastases, and body weight were measured. Results Low- and high-dose gemcitabine inhibited primary tumor growth in a dose-dependent manner, and to the greatest extent by high-dose gemcitabine compared to the untreated control (p=0.0134). In contrast, the extent of metastasis on the peritoneum was significantly increased by low-dose gemcitabine compared to the untreated control (p=0.0112). The extent of metastasis showed no significant difference between the untreated control and mice treated with high-dose gemcitabine. Body weight of the treated mice was not significantly different from that of the untreated mice. Conclusion The use of very bright GFP expressing of BxPC-3 cells and the orthotopic model demonstrated an unexpected increase in metastasis by low-dose gemcitabine. Future experiments will investigate the mechanism of this phenomenon.

Background Osteosarcoma is a recalcitrant disease treated with surgery and intensive chemotherapy as standard. The 5-year survival rate of patients with relapsed and lung metastatic osteosarcoma is as low as 20%. Materials and methods A 16-year-old patient developed left distal femoral high-grade osteosarcoma and underwent cisplatinum-based neoadjuvant chemotherapy and surgery. From the resected tumor, a patient-derived orthotopic xenograft (PDOX) model was established in the femur of nude mice. PDOX models were randomized into the following groups: untreated control, or treatment with doxorubicin (3 mg/kg, i.p., weekly for 14 days), sunitinib (40 mg/kg, oral gavage, daily for 14 days), pazopanib (100 mg/kg, oral gavage, daily for 14 days), temozolomide(25 mg/kg, oral gavage, daily for 14 days), and eribulin (1.5 mg/kg, i.p., daily for 14 days). Tumor volume and body weight were monitored twice a week. Results The osteosarcoma PDOX was resistant to doxorubicin, sunitinib, and pazopanib. In contrast, eribulin and temozolomide arrested tumor growth. Conclusion This study demonstrated the utility of the PDOX model in allowing effective from non-effective drugs to be distinguished in a model in which the tumor was growing on the organ corresponding to that of the patient.

Background/aim Osteosarcoma is a recalcitrant neoplasm which occurs predominantly in adolescents and young adults. Recently, using a patient-derived orthotopic xenograft (PDOX) model of malignant soft-tissue sarcoma (STS), we showed that oral recombinant methioninase (o-rMETase), in combination with caffeine, was more efficacious than o-rMETase alone in inhibiting STS tumor growth. In the present report, we determined the efficacy of o-rMETase combined with oral caffeine on a cisplatinum (CDDP)-resistant osteosarcoma PDOX model. Materials and methods Osteosarcoma PDOX models were randomly divided into seven treatment groups (6 mice in each group): untreated control; CDDP alone; o-rMETase alone; o-rMETase with caffeine; CDDP plus o-rMETase; CDDP plus caffeine; and CDDP plus o-rMETase with caffeine. Tumor size and body weight were measured throughout the treatment. Results Tumors regressed after treatment with CDDP plus o-rMETase with caffeine. Tumors treated with CDDP plus o-rMETase with caffeine also had the most necrosis. Conclusion The combination of o-rMETase and caffeine together with first-line chemotherapy was efficacious for drug-resistant osteosarcoma and has clinical potential in the treatment of this highly-resistant neoplasm.

Chemotherapy-resistant osteosarcoma is a recalcitrant disease. It is a frequent cause of death to the patients who are usually adolescent or young adults. The goal of the present study was to determine the efficacy of the combination of olaratumab (OLA), doxorubicin (DOX), and cisplatinum (CDDP) on osteosarcoma, which is resistant to first-line therapy, in a patient-derived orthotopic xenograft (PDOX) model. The osteosarcoma PDOX model was randomized into six treatment groups of six mice: control; CDDP alone; DOX and CDDP; OLA + DOX; OLA + CDDP; and OLA + DOX and CDDP. Tumor size and body weight were measured during 14 days of treatment. Tumor growth was regressed only by the treatment with a combination of OLA + DOX and CDDP. Tumors treated with this three-drug combination had the most tumor necrosis and the lowest Ki-67 index. The present study demonstrates the power of the PDOX model to identify novel effective treatment strategy for chemotherapy-resistant osteosarcoma.

BACKGROUND/AIM Liver metastasis in colorectal-cancer is a recalcitrant disease. To develop precision individualized therapy of this disease, we developed a patient-derived orthotopic xenograft (PDOX) model of colorectal-cancer liver metastasis. In the present report, we evaluated the efficacy of oral recombinant methioninase (o-rMETase) in combination with 5-fluorouracil (5-FU) and oxaliplatinum (OXA) on the colorectal-cancer liver metastasis PDOX mouse model. MATERIALS AND METHODS Colorectal-cancer liver metastasis PDOX models were randomized into three groups of seven mice. Group 1, untreated control with phosphate buffered saline (PBS); Group 2, treated with 5-FU + OXA; and Group 3, treated with 5-FU + OXA + o-rMETase. RESULTS The colorectal-cancer liver metastasis PDOX model was resistant to 5-FU + OXA (p=0.83 at day 15 of treatment, Group 2). In contrast, the colorectal-cancer liver metastasis PDOX model was arrested by o-rMETase combined with 5-FU + OXA (p

Background/aim Osteosarcoma is a rare but recalcitrant type of bone cancer. To discover an effective therapy for osteosarcoma, we used a patient-derived orthotopic xenograft (PDOX) mouse model. A PDOX mouse model has been established for all major cancer types. Strong synergistic efficacy of sorafenib (SFN) and everolimus (EVL) has been demonstrated in several cancers. In the present study, we examined the efficacy of a SFN and EVL combination on a doxorubicin (DOX)-resistant osteosarcoma PDOX. Materials and methods The osteosarcoma PDOX models were randomly divided into five treatment groups, each containing six mice: Control; DOX; SFN; EVL; and a combination of SFN and EVL. Mice were treated for 14 days. To observe the efficacy of these treatments, tumor size and body weight were measured, and histological sections were analyzed. Results Tumor growth regression was observed only in the mice treated with the combination of SFN-EVL. Histological analysis revealed necrosis with degenerative changes in tumors treated with a combination of SFN-EVL. Conclusion A SFN-EVL combination could be a novel effective treatment option for osteosarcoma.

BACKGROUND/AIM Patient-derived orthotopic xenograft (PDOX) models have patient-like clinical features and may be imaged, in case of some cancers, by passaging of the tumors through transgenic nude mice expressing red-fluorescent protein (RFP) where they stably acquire RFP expressing stroma. The aim of the present study was to quantify red fluorescent area and intensity in colon-cancer peritoneal metastases in PDOX models in non-transgenic nude mice after passage in RFP transgenic nude mice by non-invasive external fluorescence imaging. MATERIALS AND METHODS Tumor fragments originating from a colon cancer patient with peritoneal metastases were implanted in transgenic RFP nude mice. Resultant tumors were harvested, and fragments were implanted in the same strain a second time. Passaged tumors stably acquired RFP-expressing stroma from their transgenic hosts. The tumor with RFP-expressing stromal cells were harvested and implanted orthotopically in non-transgenic nude mice. At eight weeks post-implantation, non-invasive external RFP images were obtained. RFP area and intensity were measured and correlated with tumor weight and volume. RESULTS Metastatic patient colon cancer can be stably and brightly labeled by passage in transgenic RFP-expressing nude mice such that tumor growth could be non-invasively imaged. Tumor growing could be non-invasively imaged when passaged to non-transgenic nude mice. A strong correlation between fluorescence intensity and area values with tumor weight and volume were established by external fluorescence imaging. CONCLUSION This new tumor model of metastatic colon cancer can be used to evaluate novel therapeutics in real time for this recalcitrant disease.

Olaratumab (OLA), a monoclonal antibody against platelet-derived growth factor receptor alpha (PDGFRα), has recently been used against soft-tissue sarcoma (STS) combined with doxorubicin (DOX), with limited efficacy. The goal of the present study was to determine the efficacy of OLA in combination with DOX and ifosfamide (IFO) on STS. Undifferentiated soft-tissue sarcoma (USTS) from a striated muscle of a patient was grown orthotopically in the right biceps femoris muscle of nude mice to establish USTS patient-derived orthotopic xenograft (PDOX) model. USTS PDOX tumors were treated with OLA alone, DOX alone, DOX combined with IFO, OLA combined with DOX or IFO, and OLA combined with DOX and IFO. Tumor size and body weight were measured during the 14 days of treatment. Tumor growth was arrested by OLA combined with DOX and IFO. Tumors treated with OLA combined with DOX and IFO had the most necrosis. The present study demonstrates the power of the PDOX model to identify the novel effective treatment strategy of the combination of OLA, DOX and IFO for soft-tissue sarcomas.

Follicular dendritic cell sarcoma (FDCS) is a very rare and highly recalcitrant disease. A patient's doxorubicin-resistant FDCS was previously established orthotopically on the right high thigh into the biceps femoris of mice to establish a patient-derived orthotopic xenograft (PDOX) model. The aim of the present manuscript was to identify an effective drug for this recalcitrant tumor. Here, we evaluated the efficacy of temozolomide (TMZ), trabectedin (TRAB) and pazopanib (PAZ) on the FDCS PDOX model. PDOX mouse models were randomized into five groups of eight to nine mice, respectively. Group 1, untreated control with PBS, i.p.; Group 2, treated with doxorubicin (DOX), 2.4 mg/kg, i.p., weekly for 3 weeks; Group 3, treated with PAZ, 50 mg/kg, oral gavage, daily for 3 weeks; Group 4, treated with TMZ, 25 mg/kg, oral gavage, daily for 3 weeks; Group 5, treated with TRAB, 0.15 mg/kg, i.v., weekly for 3 weeks. Body weight and tumor volume were assessed 2 times per week. TMZ arrested the FDCS PDOX model compared to the control group (p 0.05). PAZ and TRAB did not have significant efficacy compared to the control group (p = 0.99, p = 0.69 respectively). The PDOX tumor was resistant to DOX (p= 0.99). as was the patient. The present study demonstrates that TMZ is effective for a PDOX model of FDCS established from a patient who failed DOX treatment, further demonstrating the power of PDOX to identify effective therapy including for tumors that failed first line therapy.

Recurrent osteosarcoma is a chemotherapy-resistant disease. Individualized precision therapy is needed for this disease. Toward this goal, we have developed the patient-derived othotopic xenograft (PDOX) mouse model of all major cancer types including osteosarcoma. Synergistic efficacy of trabectedin (TRAB) and irinotecan (IRT) has been reported in Ewing's sarcoma, soft-tissue sarcoma, and ovarian cancer. However, the efficacy of this combination on osteosarcoma is not known. The goal of present study was to determine the efficacy of the TRAB and IRT combination on cisplatinum (CDDP)-resistant osteosarcoma PDOX. The osteosarcoma PDOX models were randomized into five treatment groups of six mice: Untreated control; CDDP alone; TRAB alone; IRT alone; and TRAB and the IRT combination. Tumor size and body weight were measured during the 14 days of treatment. Tumor growth was regressed only by the TRAB-IRT combination. Tumors treated with the TRAB-IRT combination had the most tumor necrosis with degenerative change. The present study demonstrates the power of the PDOX model to identify a novel effective treatment strategy of the TRAB and IRT combination for chemotherapy-resistant osteosarcoma.

Olaratumab (OLA) is a monoclonal antibody against platelet-derived growth factor receptor alpha. OLA has recently been used against soft-tissue sarcoma (STS) combined with doxorubicin (DOX), but with limited efficacy. The goal of present study was to determine the efficacy of OLA combined with gemcitabine (GEM) and docetaxel (DOC) on a chemotherapy-resistant STS patient-derived orthotopic xenograft (PDOX). Undifferentiated soft-tissue sarcoma (USTS) from a striated muscle of a patient was grown orthotopically in the right biceps femoris muscle of nude mice to establish the PDOX model. The USTS PDOX was treated with GEM alone, GEM combined with DOC, OLA combined with DOX or GEM, and OLA combined with GEM and DOC. Tumor size and body weight were measured during the 14 days of treatment. Tumor growth was arrested only by OLA combined with GEM and DOC. Tumors treated with OLA combined with GEM and DOC also had the most necrosis. The present study demonstrates the power of the PDOX model to identify the novel effective treatment strategy of the combination of OLA, GEM and DOC for drug-resistant soft-tissue sarcoma.

Background Osteosarcoma is the most frequent malignant bone neoplasm. The efficacy of combination therapy of a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor and a mammalian-target-of-rapamycin (mTOR) inhibitor was previously reported in several cancer types. In the present study, we evaluated the efficacy of a combination of palbociclib (CDK 4/6 inhibitor) and everolimus (mTOR inhibitor) on an osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model. Materials and methods osteosarcoma PDOX mouse models were randomized into five treatment groups of seven mice each: Group 1, untreated control; group 2, doxorubicin treatment; group 3, palbociclib treatment; group 4, everolimus treatment; group 5, palbociclib-everolimus combination treatment. Treatment duration was 2 weeks. Results The palbociclib-everolimus combination reduced the tumor-volume ratio in the osteosarcoma PDOX mouse model compared with the control and doxorubicin (p=0.018). Everolimus alone also inhibited osteosarcoma PDOX growth compared to the control (p=0.04), but less than the combination. Palbociclib alone and doxorubicin were ineffective. There were no significant body-weight losses in any group. Only the palbociclib-everolimus combination induced extensive tumor necrosis observed histopathologically. Conclusion The present study demonstrated that the combination of CDK4/6 and mTOR inhibitors can be a translatable approach for doxorubicin-resistant osteosarcoma in the clinic.

Background Soft tissue defects following wide excision of malignant soft tissue tumors (STTs) are sometimes too large for primary closure, especially in the lower legs where available soft tissue is limited. This study aimed to determine the clinical outcomes of reconstruction of a defect after wide excision of an STT with a veno-accompanying artery fasciocutaneous (VAF) flap in the lower leg. Methods This study comprised 9 patients with malignant STTs who had undergone reconstructive surgeries using VAF flaps after wide excisions, between October 2010 and September 2017. We retrospectively reviewed and collected data involving age, sex, follow-up period, histological diagnosis, surgical procedures, size and location of defects, size and location of the flaps, venous source of the flaps, direction of the pedicles, closing of donor sites, perioperative chemotherapies, postoperative complications, and the presence of postoperative local recurrence and metastasis. Results The median follow-up period was 91.5 (range, 15.5–189.0) months. Four patients had defects located around the knee, 3 patients had defects located on the calf, and 2 patients had defects located around the ankle. The mean flap size was 95.6 × 119.4 (range, 50 × 100–130 × 140) mm. Six patients had venous sources from the small saphenous vein and 3 patients had venous sources from the great saphenous vein. The pedicles were proximally based in 4 patients and distally based in 5 patients. All flaps remained viable without any complications. Conclusions Our findings showed that the VAF flap was easily elevated and reliable. Furthermore, it was effective in reconstructing soft tissue defects following wide excisions of STTs in the lower leg.

A 35-year-old man presented with a four-year history of a growing mass on the anterior aspect of his left elbow. Magnetic resonance imaging revealed a soft tissue tumor in the brachialis muscle extending to the cubital fossa. Following an open biopsy, the tumor was diagnosed as a monophasic fibrous synovial sarcoma. After neoadjuvant chemotherapy, the patient underwent wide excision and reconstruction of the elbow joint with a pedicle frozen autograft. At the final follow-up four years after surgery, the elbow range of motion was 0-120˚. Although there were signs of osteoarthritis, there was no narrowing of the joint -, and the patient experienced only mild pain. To the best of our knowledge, the present case report is the first to describe wide tumor excision and reconstruction using a pedicle frozen autograft of the elbow. This method should be considered after excision of malignant bone and soft tissue tumors, especially in non-weight-bearing joints. Further cases have to be evaluated to understand the complications and long-term prognosis of this procedure.

In order to identify more effective therapy for recalcitrant osteosarcoma, we evaluated the efficacy of an mTOR-VEGFR inhibitor combination on tumor growth in a unique osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model derived from the lung metastasis of an osteosarcoma patient who failed doxorubicin therapy. We also determined the efficacy of this inhibitor combination on angiogenesis using an in vivo Gelfoam fluorescence angiogenesis mouse model implanted with osteosarcoma patient-derived cells (OS-PDCs). PDOX models were randomly divided into five groups of seven nude mice. Group 1, control; Group 2, doxorubicin (DOX); Group 3, everolimus (EVE, an mTOR and VEGF inhibitor); Group 4, pazopanib (PAZ, a VEGFR inhibitor); Group 5, EVE-PAZ combination. Tumor volume and body weight were monitored 2 times a week. The in vivo Gelfoam fluorescence angiogenesis assay was performed with implanted OS-PDCs. The nude mice with implanted Gelfoam and OSPDCs also were divided into the four therapeutic groups and vessel length was monitored once a week. The EVE-PAZ combination suppressed tumor growth in the osteosarcoma PDOX model and decreased the vessel length ratio in the in vivo Gelfoam fluorescent angiogenesis model, compared with all other groups (p

There are no effective treatments for leiomyosarcoma (LMS) spreading intraabdominally. The aim of this study was to develop precision chemotherapy for recurrent peritoneal LMS metastases in a patient-derived orthotopic xenograft (PDOX) model. The LMS PDOX models were established orthotopically on the dome of the bladder of nude mice. The LMS PDOX models were randomized into 6 groups when the tumor volume reached 80 mm3: G1: untreated control; G2: doxorubicin (DOX) (DOX: i.p., 3 mg/kg, weekly, 3 weeks); G3: DOX combined with olaratumab (OLA) (DOX: i.p., 3 mg/kg, weekly, 3 weeks; OLA: i.p., 40 mg/kg, 3 times/week, 3 weeks); G4: gemcitabine (GEM) combined with docetaxel (DOC) (GEM: i.p., 100 mg/kg, weekly, 3 weeks; DOC: i.p., 20 mg/kg, weekly, 3 weeks); G5: pazopanib (PAZ) (PAZ: p.o., 100 mg/kg, daily, 3 weeks); G6: palbociclib (PAL) (PAL: p.o., 100 mg/kg, daily, 3 weeks). All mice were sacrificed on day 22. Body weight was assessed twice a week. Tumor volume was measured on day 0 and day 22. Although all regimens had a significant efficacy compared to the untreated group (P

Background/aim Undifferentiated pleomorphic sarcoma (UPS) is a common soft tissue sarcoma and highly recalcitrant. We have previously developed patient-derived orthotopic xenograft (PDOX) mouse models of UPS and other major sarcoma types. Unlike PDOX models of other cancer types, it has been difficult to demonstrate metastasis in the sarcoma PDOX models. Materials and methods To visualize metastasis at high resolution in the UPS PDOX model, established tumor fragments were implanted in transgenic nude mice expressing red fluorescent protein (RFP) for one passage. The tumors acquired RFP-expressing stroma from transgenic host. UPS tumor with RFP stromal cells were harvested and implanted orthotopically in non-transgenic nude mice. After six weeks of UPS tumor growth in the PDOX model, the primary tumor was imaged non-invasively and lung, liver, and spleen were resected and imaged ex-vivo in order to visualize the presence of RFP, with a FluorVivo® imaging system and FV1000® confocal laser microscope, respectively. Results The primary tumor was imaged non-invasively. Confocal microscopy visualized the presence of RFP in the lung and liver indicating metastases in these organs. This is the first report of metastasis in a sarcoma PDOX model. Conclusion This study should prove very useful to screen for anti-metastatic drugs for the PDOX donor patients and to understand the metastatic process in sarcoma.

Myxofibrosarcoma (MFS) is the most common sarcomas in elderly patients and is either chemo-resistant or recurs with metastasis after chemotherapy. This recalcitrant cancer in need of improved treatment. We have established a patient-derived orthotopic xenograft (PDOX) of MFS. The MFS PDOX model was established in the biceps femoris of nude mice and randomized into 7 groups of 7 mice each: control; doxorubicin (DOX); pazopanib (PAZ); temozolomide (TEM); Irinotecan (IRN); IRN combined with TEM; IRN combined with cisplatinum (CDDP) and Salmonella typhimurium A1-R (S. typhimurium A1-R). Treatment was evaluated by relative tumor volume and relative body weight. The MFS PDOX models were DOX, PAZ, and TEM resistant. IRN combined with TEM and IRN combined with CDDP were most effective on the MFS PDOX. S. typhimurium A1-R arrested the MFS PDOX tumor. There was no significant body weight loss in any group. The present study suggests that the combination of IRN with either TEM or CDDP, and S. typhimurium have clinical potential for MFS.

BACKGROUND/AIM Synovial sarcoma (SS) is a recalcitrant neoplasm with low chemosensitivity. We recently reported that recombinant methioninase (rMETase) inhibited SS growth in a patient-derived orthotopic xenograft (PDOX) mouse model and was more effective when administered in combination with the first-line drug doxorubicin (DOX). Caffeine enhances the efficacy of anticancer drugs by overcoming drug-induced cell-cycle arrest and increasing subsequent apoptosis. Here, we determined the efficacy of oral recombinant methioninase (o-rMETase) in combined with caffeine on an SS-PDOX model. MATERIALS AND METHODS Mice bearing SS-PDOX tumors were randomized into four treatment groups of six: Untreated control; o-rMETase alone; o-rMETase with caffeine; DOX plus o-rMETase with caffeine. Tumor size and body weight were measured during the treatment and plasma L-methionine (MET) levels were measured at the end of treatment. RESULTS All treatments significantly inhibited SS-PDOX tumor growth. Combining caffeine with o-rMETase was more effective than o-rMETase alone. DOX combined with o-rMETase and caffeine led to regression of SS-PDOX. Plasma MET levels were reduced with o-rMETase treatment. CONCLUSION These results suggest that combining o-rMETase and caffeine along with first-line chemotherapy can be highly effective for SS and has clinical potential for this recalcitrant disease.

Recombinant methioninase (rMETase) was previously administered as an injectable drug to target methionine dependence of cancer. Recently, we observed that rMETase could be administered orally (o-rMETase) in a patient-derived orthotopic xenograft (PDOX) mouse model of melanoma. Here, we determined the efficacy of o-rMETase on a pancreatic cancer PDOX model. Forty pancreatic cancer PDOX mouse models were randomized into four groups of 10 mice each. o-rMETase was significantly more effective than i.p.-rMETase, but the combination of both was significantly more effective than either alone. Acquired gemcitabine resistance is a major factor in the recalcitrance of pancreatic cancer. We tested a human pancreatic cancer cell line, which has acquired >100-fold GEM-resistance (PK-9R) than its parental cell line PK-9. In contrast to GEM, both cell lines were very sensitive to rMETase. In orthotopic nude mouse models of PK-9 and PK-9R, GEM inhibited tumor growth in PK-9 but not PK-9R. In contrast, o-rMETase could inhibit both tumors. The combination of GEM + o-rMETase could regress the PK-9 tumor and inhibit PK-9R tumor growth. The present study shows that o-rMETase is effective and overcomes acquired GEM resistance in pancreatic cancer and demonstrates the clinical potential of this strategy.

Gemcitabine (GEM) is first-line therapy for pancreatic cancer but has limited efficacy in most cases. Nanoparticle-albumin bound (nab)-paclitaxel is becoming first-line therapy for pancreatic cancer, but also has limited efficacy for pancreatic cancer. Our goal was to improve the treatment outcome in patient-like models of pancreatic cancer. We previously established patient-derived orthotopic xenografts (PDOX) pancreatic cancers from two patients. The pancreatic tumor was implanted orthotopically in the pancreatic tail of nude mice to establish the PDOX models. Five weeks after implantation, 50 PDOX mouse models were randomized into five groups of 10 mice for each pancreatic cancer PDOX: untreated control; GEM (100 mg/kg, i.p., once a week for 2 weeks); GEM + nab-PTX (GEM: 100 mg/kg, i.p., once a week for 2 weeks, nab-PTX: 10 mg/kg, i.v., twice a week for 2 weeks); S. typhimurium A1-R (5 × 10(7) CFU/100 μl, i.v., once a week for 2 weeks); GEM + S. typhimurium A1-R (GEM: 100 mg/kg, i.p., once a week for 2 weeks, S. typhimurium A1-R; 5 × 10(7) CFU/100 μl, i.v., once a week for 2 weeks). GEM + nab-PTX was significantly more effective than GEM alone in one PDOX model (p = 0.0004), but there was no significant difference in the other PDOX model. The combination of GEM + S. typhimurium A1-R regressed both PDOX models. These results show S. typhimurium A1-R can overcome the ineffectiveness or partial effectiveness of GEM in patient-like models of pancreatic cancer and demonstrate clinical potential for this combination.

Pleomorphic liposarcoma (PLPS) is a recalcitrant soft-tissue sarcoma (STS) subtype in need of transformative therapy. We have previously established a patient-derived orthotopic xenograft (PDOX) model, of PLPS with PDGFRA amplification, using surgical orthotopic implantation (SOI). In the present study, the PLPS PDOX model was randomized into three groups of seven mice each: untreated control; doxorubicin (DOX)-treated; and treated with Salmonella typhimurium A1-R (S. typhimurium A1-R) expressing green fluorescent protein (GFP). Tumor volume and body weight were monitored during the treatment period. The PLPS PDOX was resistant to DOX. In contrast, the PLPS PDOX was highly sensitive to S. typhimurium A1-R. There was no significant body-weight loss among these three groups. Fluorescence imaging demonstrated that S. typhimurium A1-R-GFP was very effective to target the PLPS PDOX tumor. The present study demonstrates that a PLPS PDOX, resistant to first-line therapy DOX, was highly sensitive to tumor targeting S. typhimurium A1-R.

Synovial sarcoma (SS) is a recalcitrant subgroup of soft tissue sarcoma (STS). A tumor from a patient with high grade SS from a lower extremity was grown orthotopically in the right biceps femoris muscle of nude mice to establish a patient-derived orthotopic xenograft (PDOX) mouse model. The PDOX mice were randomized into the following groups when tumor volume reached approximately 100 mm3: G1, control without treatment; G2, doxorubicin (DOX) (3 mg/kg, intraperitoneal [i.p.] injection, weekly, for 2 weeks; G3, rMETase (100 unit/mouse, i.p., daily, for 2 weeks); G4 DOX (3mg/kg), i.p. weekly, for 2 weeks) combined with rMETase (100 unit/mouse, i.p., daily, for 2 weeks). On day 14 after treatment initiation, all therapies significantly inhibited tumor growth compared to untreated control, except DOX: (DOX: p = 0.48; rMETase: p < 0.005; DOX combined with rMETase < 0.0001). DOX combined with rMETase was significantly more effective than both DOX alone (p < 0.001) and rMETase alone (p < 0.05). The relative body weight on day 14 compared with day 0 did not significantly differ between any treatment group or untreated control. The results indicate that r-METase can overcome DOX-resistance in this recalcitrant disease.

Background: Ewing’s sarcoma (ES) is a recalcitrant disease in need of transformative therapeutics. Objectives: The aim of this study was to investigate the efficacy of tumor-selective Salmonella typhimurium A1-R combined with tumor metabolism targeting with oral administration of recombinant methioninase (o-rMETase), on an ES patient-derived orthotopic xenograft (PDOX) model. Methods: The ES PDOX models were previously established in the right chest wall. The ES PDOX models were randomized into 5 groups when the tumor volume reached 80 mm3: G1: untreated control; G2: doxorubicin; G3: S. typhimurium A1-R; G4: o-rMETase; G5: S. typhimurium A1-R combined with o-rMETase. All mice were sacrificed on day 15. Body weight and tumor volume were assessed twice a week. Results: S. typhimurium A1-R and o-rMETase respectively suppressed tumor growth as monotherapies (p = 0.050 and p = 0.032). S. typhimurium A1-R combined with o-rMETase regressed tumor growth significantly compared to untreated group on day 15 (p < 0.032). S. typhimurium A1-R combined with o-rMETase group was significantly more effective than S. typhimurium A1-R or o-rMETase monotherapy (p = 0.032, p = 0.032). Conclusions: The present results suggest that the combination of S. typhimurium A1-R and o-rMETase has promise to be a transformative therapy for ES.

Background/Aim: Brain metastases are found in approximately 30% of patients with epidermal-growth-factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). We compared the efficacy of two EGFR-tyrosine kinase inhibitors (TKIs), erlotinib and osimertinib on a PC-9-GFP EGFR mutant NSCLC growing in the brain of nude mice. Materials and Methods: The brain metastasis models were randomized into five groups and treated for 15 days: Control; 5 mg/kg erlotinib; 50 mg/kg erlotinib; 0.5 mg/kg osimertinib; 5 mg/kg osimertinib. Tumor volume was evaluated by non-invasive fluorescence imaging. Results: Only 5 mg/kg osimertinib, a low-dose compared to the clinically-equivalent dose, showed significant tumor regression compared to the control. Conclusion: This study strongly supports the high activity of osimertinib for intracranial lesions of EGFR-mutant NSCLC.

Sarcoma is a rare and recalcitrant malignancy. Although immune and novel targeted therapies have been tested on many cancer types, few sarcoma patients have had durable responses with such therapy. Doxorubicin and cisplatinum are still first-line chemotherapy after four decades. Our laboratory has established the patient-derived orthotopic xenograft (PDOX) model using surgical orthotopic implantation (SOI). Many promising results have been obtained using the sarcoma PDOX model for identifying effective approved drugs and experimental therapeutics, as well as combinations of them for individual patients. In this review, we present our laboratory's experience with PDOX models of sarcoma, and the ability of the PDOX models to identify effective approved agents, as well as experimental therapeutics.

Cancers are methionine (MET) and methylation addicted, causing them to be highly sensitive to MET restriction. The present study determined the efficacy of restricting MET with oral-recombinant methioninase (o-rMETase) and the DNA methylation inhibitor, azacitidine (AZA) on a chemotherapy-resistant osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model.The osteosarcoma PDOX models were randomized into five treatment groups of six mice: control; doxorubicin (DOX) alone; AZA alone; o-rMETase alone; o-rMETase-AZA combination. Tumor size and body weight were measured during the 14 days of treatment.We found that tumor growth was arrested only by the o-rMETase-AZA combination treatment, as tumors with this treatment exhibited tumor necrosis with degenerative change.This study suggests that o-rMETase-AZA combination has clinical potential for patients with chemoresistant osteosarcoma.

Multidrug resistance (MDR) which results in chemoresistance is a major problem in osteosarcoma. P-glycoprotein (P-gp) plays a critical role in MDR by pumping out chemotherapy agents. Peroxisome proliferator activated receptor gamma (PPARγ) is a nuclear receptor involved in cellular differentiation and proliferation. Recently, a correlation between the expression and activity of PPARγ and the expression of P-gp-associated with MDR, has been reported in several human cancers. The present study determined if pioglitazone (PIO), a PPARγ agonist, could modulate P-gp and overcome doxorubicin (DOX)-resistance in a patient-derived orthotopic xenograft (PDOX) model of osteosarcoma. P-gp mRNA expression was quantified in 143B human osteosarcoma cells treated with DOX with/without PIO. The osteosarcoma PDOX models were randomized into four treatment groups of six mice: Control; PIO alone; DOX alone; DOX and PIO combination. Tumor size and body weight were measured during the 14 days of treatment. DOX significantly induced P-gp mRNA in a dose-dependent manner in 143B cells. PIO inhibited the increase of P-gp mRNA induced by DOX treatment when co-administrated with DOX. Tumor growth was inhibited the most by the DOX-PIO combination. Tumors treated with the DOX-PIO combination also had the most tumor necrosis. This study suggests that the DOX-PIO combination could be used in the clinic for osteosarcoma patients who develop DOX-resistance.

BACKGROUND/AIM Recurrent osteosarcoma is a recalcitrant disease; therefore, an improved strategy is urgently needed to provide therapy. In order to develop a novel strategy for this disease, our lab has developed a patient-derived orthotopic xenograft (PDOX) mouse model for osteosarcoma. The combination of sorafenib (SFN) and palbociclib (PAL) was shown to be effective of hepatocellular carcinoma. However, whether this combination is efficacious on osteosarcoma has not been reported. The aim of this study was to determine the efficacy of the SFN and PAL combination on a cisplatinum (CDDP)-resistant osteosarcoma PDOX model. MATERIALS AND METHODS Osteosarcoma PDOX models were randomly divided into five treatment groups: untreated-control, CDDP, SFN, PAL and the combination of SFN and PAL. RESULTS Of these agents, the SFN-PAL combination significantly regressed tumor growth, and enhanced tumor necrosis with degenerative changes in the osteosarcoma PDOX. CONCLUSION The SFN-PAL combination is an effective treatment strategy for osteosarcoma and therefore holds promise for clinical efficacy.

Patient-derived orthotopic xenograft (PDOX) models have patient-like clinical features and may be imaged, in case of some cancers, by passaging of the tumors through transgenic nude mice expressing red-fluorescent protein (RFP) where they stably acquire RFP expressing stroma. The aim of the present study was to quantify red fluorescent area and intensity in colon-cancer peritoneal metastases in PDOX models in non-transgenic nude mice after passage in RFP transgenic nude mice by non-invasive external fluorescence imaging.Tumor fragments originating from a colon cancer patient with peritoneal metastases were implanted in transgenic RFP nude mice. Resultant tumors were harvested, and fragments were implanted in the same strain a second time. Passaged tumors stably acquired RFP-expressing stroma from their transgenic hosts. The tumor with RFP-expressing stromal cells were harvested and implanted orthotopically in non-transgenic nude mice. At eight weeks post-implantation, non-invasive external RFP images were obtained. RFP area and intensity were measured and correlated with tumor weight and volume.Metastatic patient colon cancer can be stably and brightly labeled by passage in transgenic RFP-expressing nude mice such that tumor growth could be non-invasively imaged. Tumor growing could be non-invasively imaged when passaged to non-transgenic nude mice. A strong correlation between fluorescence intensity and area values with tumor weight and volume were established by external fluorescence imaging.This new tumor model of metastatic colon cancer can be used to evaluate novel therapeutics in real time for this recalcitrant disease.