Patient-derived orthotopic xenograft models of sarcoma

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.

Combination Treatment With Sorafenib and Everolimus Regresses a Doxorubicin-resistant Osteosarcoma in a PDOX Mouse Model

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.

Oral Recombinant Methioninase, Combined With Oral Caffeine and Injected Cisplatinum, Overcome Cisplatinum-Resistance and Regresses Patient-derived Orthotopic Xenograft Model of Osteosarcoma

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.

Oral Recombinant Methioninase Overcomes Colorectal-cancer Liver Metastasis Resistance to the Combination of 5-Fluorouracil and Oxaliplatinum in a Patient-derived Orthotopic Xenograft Mouse Model

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<0.01 at day 15, Group 3). No significant body-weight differences were observed among the groups.

CONCLUSION

The combination therapy of 5-FU and OXA with o-rMETase can overcome the resistance of first line drugs for colorectal-cancer liver metastasis.

Eribulin Suppressed Cisplatinum- and Doxorubicin-resistant Recurrent Lung Metastatic Osteosarcoma in a Patient-derived Orthotopic Xenograft Mouse Model

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.

Oral recombinant methioninase combined with oxaliplatinum and 5-fluorouracil regressed a colon cancer growing on the peritoneal surface in a patient-derived orthotopic xenograft mouse model

The aim of this study was to determine the efficacy of oral recombinant methioninase (o-rMETase) on a model of colon cancer growing on the peritoneal surface using a patients-derived orthotopic xenograft (PDOX) nude mouse model. Forty PDOX mouse models with colon cancer growing on the peritoneum were divided into 4 groups of 10 mice each by measuring the tumor size and fluorescence intensity: untreated control; 5-fluorouracil (5-FU) (50 mg/kg, once a week for two weeks, ip) and oxaliplatinum (OXA) (6  mg/kg, once a week for two weeks, ip); o-rMETase (100 units/day, oral 14 consecutive days); combination 5-FU + OXA and o-rMETase. All treatments inhibited tumor growth compared to the untreated control. The combination of 5-FU + OXA plus o-rMETase was significantly more efficacious than the control and each drug alone and was the only treatment that caused tumor regression. The present study is the first demonstrating the efficacy of o-rMETase combination therapy on a PDOX model of peritoneal colon cancer, suggesting potential clinical development of o-rMETase in a recalcitrant cancer.

Pioglitazone, an agonist of PPARγ, reverses doxorubicin-resistance in an osteosarcoma patient-derived orthotopic xenograft model by downregulating P-glycoprotein expression

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.

Efficacy of oral recombinant methioninase combined with oxaliplatinum and 5-fluorouracil on primary colon cancer in a patient-derived orthotopic xenograft mouse model

The aim of this study was to determine the efficacy of oral recombinant methioninase (o-rMETase) on a colon cancer primary tumor using a patient-derived orthotopic xenograft (PDOX) nude mouse model. Forty colon cancer primary tumor PDOX mouse models were divided into 4 groups of 10 mice each (total 40 mice) by measuring the tumor size. The groups were as follows: untreated control; 5-fluorouracil (5-FU) (50 mg/kg, once a week for two weeks, N = 10 mice) and oxaliplatinum (OXA) (6 mg/kg, once a week for two weeks, N = 10 mice); o-rMETase (100 units/day, oral 14 consecutive days, N = 10 mice); combination of 5-FU + OXA and o-rMETase (N = 10 mice). All treatments inhibited tumor growth compared to the untreated control. The combination of 5-FU + OXA and o-rMETase was significantly more efficacious than other treatments. The present study demonstrates the efficacy of o-rMETase combination therapy on a PDOX colon cancer primary tumor, suggesting potential clinical development of o-rMETase in recalcitrant cancer.

A pharmacogenomic analysis using L1000CDS2 identifies BX-795 as a potential anticancer drug for primary pancreatic ductal adenocarcinoma cells

Pancreatic cancer is one of the leading causes of cancer death, mainly due to the absence of early diagnostic tool and effective therapeutic agents. To identify an effective therapeutic agent for pancreatic ductal adenocarcinoma cells (PDAC), we used 10 Gene Expression Omnibus (GEO) data sets and L1000CDS² pharmacogenetic search tool and obtained chemical "perturvants" that were predicted to reverse the abnormal gene expression changes in PDAC. Among 20 initial candidates, we measured IC₅₀ for six compounds and identified BX-795, PDK1/TBK1 inhibitor, as a therapeutic candidate. We found that BX-795 inhibits primary PDAC cell proliferation more effectively than normal cells. Following molecular analysis revealed that BX-795 down-regulates mTOR-GSK3β pathway and trigger apoptosis. Moreover, we found that BX-795 suppresses primary PDAC cell migration via downregulation of Snail and Slug. Finally, efficacy test in patient-derived xenograft model of PDAC showed BX-795 can inhibit in vivo tumor growth as efficient as gemcitabine and a combination with trametinib further suppresses tumor growth. Collectively, these results demonstrate the BX-795 as an effective therapeutic candidate for PDAC treatment.

Sorafenib and Palbociclib Combination Regresses a Cisplatinum-resistant Osteosarcoma in a PDOX Mouse Model

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.

Tumor-sealing Surgical Orthotopic Implantation of Human Colon Cancer in Nude Mice Induces Clinically-relevant Metastases Without Early Peritoneal Carcinomatosis

BACKGROUND

Surgical orthotopic implantation of human colon cancer tissue to the ceca of mice has been used to mimic behavior of cancer in human patients for the development of precision cancer medicine. However, with the current method of serosal surface implantation (SSI) of pieces of human colon cancer tissue, cancer cells are exposed to the peritoneum, which can artificially increase the rate of peritoneal carcinomatosis (PC) during the disease course. The objective of the present study was to introduce a tumor-sealing method (TSM) and compare it with SSI for the ability to produce clinically-relevant metastases without artificial PC.

MATERIALS AND METHODS

HCT116 colon cancer cells transfected with green fluorescence protein (GFP) were cultured and then injected into the subcutaneous layer of athymic nude mice. Subcutaneous tumors were allowed to grow sufficiently to supply adequate tumor for orthotopic implantation. For SSI, a 1 mm3-sized tumor fragment was sutured to partially torn serosa of the cecum. For TSM, the blind end of the cecum was folded over the tumor fragment and sealed with sutures. At 20 days after implantation, all mice were opened to visualize PC by intravital fluorescence imaging. At necropsy, distant metastasis was investigated using frozen section of whole blocks of organs.

RESULTS

At 20 days after implantation, PC rates in the SSI group and the TSM group were 80% (12/15) and 20% (3/15), respectively (p<0.001). The liver metastasis rate was 41.7% (5/12) in the SSI group and 50% (5/10) in the TSM group (p=0.696). The lung metastasis rate was 0% (0/12) in the SSI group and 10% (1/10) in the TSM group (p=0.201). The mean survival of mice without PC on the 20th day was significantly longer than that of mice with PC on the 20th day (69.1±14.7 vs. 44.5±12.4 days, p=0.001).

CONCLUSION

These results suggest that TSM might be a more patient-like and useful method as a model of metastatic colon cancer than SSI.

Expression of anti-aging type-XVII collagen (COL17A1/BP180) in hair follicle-associated pluripotent (HAP) stem cells during differentiation

Hair-follicle-associated pluripotent (HAP) stem cells reside in the upper part of the bulge area of the the hair follicle. HAP stem cells are nestin-positive and keratin 15-negative and have the capacity to differentiate into various types of cells in vitro. HAP stem cells are also involved in nerve and spinal cord regeneration in mouse models. Recently, it was shown that the DNA-damage response in non-HAP hair follicle stem cells induces proteolysis of type-XVII collagen (COL17A1/BP180), which is involved in hair-follicle stem-cell maintenance. COL17A1 proteolysis stimulated hair-follicle stem-cell aging, characterized by the loss of stemness signatures and hair-follicle miniaturization associated with androgenic alopecia. In the present study, we demonstrate that HAP stem cells co-express nestin and COL17A1 in vitro and in vivo. The expression of HAP stem cell markers (nestin and SSEA1) increased after HAP stem-cell colonies were formed, then decreased after differentiation to epidermal keratinocytes. In contrast COL17A1 increased after differentiation to epidermal keratinocytes. These results suggest that COL17A1 is important in differentiation of HAP stem cells.

The Combination of Olaratumab with Doxorubicin and Cisplatinum Regresses a Chemotherapy-Resistant Osteosarcoma in a Patient-Derived Orthotopic Xenograft Mouse Model

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.

Peritoneal Metastases in a Patient-derived Orthotopic Xenograft (PDOX) Model of Colon Cancer Imaged Non-invasively via Red Fluorescent Protein Labeled Stromal Cells

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.

Hair-follicle-associated pluripotent stem cells derived from cryopreserved intact human hair follicles sustain multilineage differentiation potential

The bulge area of the hair follicle contains hair-follicle-associated pluripotent (HAP) stem cells. Here, we present effective cryopreservation procedures of the human hair follicle that preserve the differentiation potential of HAP stem cells. Whole hair follicles isolated from human scalp were cryopreserved by a slow-rate cooling medium and stored in liquid nitrogen. A careful thawing method was used to collect the upper parts of the human hair follicles which were cultured for four weeks in a Dulbecco’s Modified Eagle’s Medium with fetal bovine serum (FBS). Proliferating hair follicle cells were then shifted to DMEM/Ham’s Nutrient Mixture F-12 medium without FBS and allowed to grow for one week. These proliferating cells were able to produce HAP stem cell colonies with multilineage differentiation capacity. They produced keratinocytes, smooth muscle cells, cardiac muscle cells, neurons and glial cells. Interestingly, these cryopreserved hair follicles produced pluripotent HAP stem cell colonies similar to fresh follicles. These findings suggest that the cryopreserved whole human hair follicle preserves the ability to produce HAP stem cells, which will enable any individual to preserve a bank of these stem cells for personalized regenerative medicine.

The combination of gemcitabine and docetaxel arrests a doxorubicin-resistant dedifferentiated liposarcoma in a patient-derived orthotopic xenograft model

Liposarcoma (LS) is a chemotherapy-resistant disease. The aim of the present study was to find precise therapy for a recurrent dedifferentiated liposarcoma (DDLS) in a patient-derived orthotopic xenograft (PDOX) model. The DDLS PDOX models were established orthotopically in the right inguinal area of nude mice. The DDLS PDOX models were randomized into five groups: untreated; doxorubicin (DOX); gemcitabine (GEM) combined with docetaxel (DOC); pazopanib (PAZ); and yondelis (YON). On day 15, all mice were sacrificed. Measurement of tumor volume and body weight were done two times a week. The DDLS PDOX was resistant to DOX (P > 0.184). YON suppressed tumor growth significantly compared to control group (P < 0.027). However, only GEM combined with DOC arrested the tumor growth (P < 0.001). These findings suggest that GEM combined with DOC has clinical potential for this and possibly other DDLS patients.

Tumor-targeting Salmonella typhimurium A1-R overcomes nab-paclitaxel resistance in a cervical cancer PDOX mouse model

PURPOSE

Cervical cancer is a recalcitrant disease. To help overcome this problem, we previously established a patient-derived orthotopic xenograft (PDOX) model of cervical cancer. In the previous study, we found the tumor to be resistant to nab-paclitaxal (nab-PTX). We also previously developed the tumor-targeting bacteria Salmonella typhimurium A1-R (S. typhimurium A1-R). The aim of the present study was to investigate the efficacy of S. typhimurium A1-R to overcome nab-PTX resistance in the cervical cancer PDOX model.

METHODS

Cervical-cancer tumor fragments were implanted orthotopically into the neck of the uterus of nude mice. The cervical-cancer PDOX models were randomized into the following four groups after the tumor volume reached 60 mm3: G1: untreated group; G2: nab-PTX (i.v., 10 mg/kg, biweekly, 3 weeks); G3: Salmonella typhimurium A1-R (i.v., 5 × 107 CFU/body, weekly, 3 weeks); G4: nab-PTX combined with Salmonella typhimurium A1-R (nab-PTX, 10 mg/kg, i.v., biweekly, 3 weeks; S. typhimurium A1-R, 5 × 107 CFU/body, i.v., weekly, 3 weeks). Each group comprised eight mice. All mice were sacrificed on day 22. Tumor volume was measured on day 0 and day 22. Body weight was measured twice a week.

RESULTS

Nab-PTX and Salmonella typhimurium A1-R did not show significant efficacy as monotherapy compared to the control group (P = 0.564 and P = 0.120, respectively). In contrast, nab-PTX combined with Salmonella typhimurium A1-R significantly suppressed tumor growth compared to the untreated control group and nab-PTX group (P < 0.001 and P = 0.026, respectively).

CONCLUSIONS

Salmonella typhimurium A1-R has potential future clinical application to overcome drug resistance in cervical cancer.

Pazopanib regresses a doxorubicin-resistant synovial sarcoma in a patient-derived orthotopic xenograft mouse model

Synovial sarcoma (SS) is an aggressive subgroup of soft tissue sarcoma (STS) with high grade and high risk of metastasis. However, there are no systemic therapies available that target SS. Therefore, transformative therapy is needed for SS. To establish a patient-derived orthotopic xenograft (PDOX) model, a patient tumor with high grade SS from a lower extremity was grown orthotopically in the right biceps femoris muscle of mice. To test the efficacy of drugs, the PDOX models were randomized into five groups: Group 1 (G1), control-without treatment; Group 2 (G2), doxorubicin (DOX); Group 3 (G3), temozolomide (TEM); Group 4 (G4), gemcitabine (GEM) combined with docetaxel (DOC); and Group 5 (G5), pazopanib (PAZ). Tumor size and body weight were measured twice a week for each treatment group. A significant growth inhibition was found on day 14 in each treatment group compared to the untreated control, except for DOX. However, PAZ was significantly more effective than both TEM and GEM + DOC. In addition, PAZ significantly regressed the tumor volume on day 14 compared to day 0. No change was found in body weight on day 14 compared to day 0 in any treatment group. The present study demonstrated the precision of the SS PDOX models for individualizing SS therapy.

Temozolomide targets and arrests a doxorubicin-resistant follicular dendritic-cell sarcoma patient-derived orthotopic xenograft mouse model

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.