Patient-derived xenograft models for gastrointestinal tumors: A single-center retrospective study.

Background: Patient-derived xenograft (PDX) models have shown a great efficiency in preclinical and translational applications. Gastrointestinal (GI) tumors have a strong heterogeneity, and the engraftment rate of PDX models remarkably vary. However, the clinicopathological and molecular characteristics affecting the engraftment rate still remain elusive. Methods: A total of 312 fresh tumor tissue samples from patients with GI cancer were implanted into immunodeficient mice. The median follow-up time of patients was 37 months. Patients' characteristics were compared in terms of PDX growth and overall survival. PDX models of 3-6 generations were used for drug evaluation. Results: In total, 171 (54.8%, 171/312) PDX models were established, including 85 PDX models of colorectal cancer, 21 PDX models of esophageal cancer, and 65 PDX models of gastric cancer. Other than tumor site, histology, differentiation degree, and serum alpha-fetoprotein (AFP) level, no significant differences were found between transplantation of xenografts and patients' characteristics. For patients who had undergone neoadjuvant therapy, the incidence of tumor formation was higher in those with progressive disease (PD) or stable disease (SD). In gastric cancer, the results showed a higher transplantation rate in deficient mismatch repair (dMMR) tumors, and Ki-67 could be an important factor affecting the engraftment rate. The gene mutation status of RAS and BRAF, two important molecular markers in colorectal cancer, showed a high degree of consistency between patients' tumors and PDXs. However, no significant effects of these two mutations on PDX engraftment rate were observed. More importantly, in this study although KRAS mutations were detected in two clinical cases, evident tumor inhibition was still observed after cetuximab treatment in both PDX models and patients. Conclusion: A large-scale PDX model including 171 cases was successfully established for GI tumors in our center. The relationship between clinicopathological and molecular features and engraftment rates were clarified. Furthermore, this resource provides us with profound insights into tumor heterogeneity, making these models valuable for PDX-guided treatment decisions, and offering the PDX model as a great tool for personalized treatment and translation research.

Efficacy and safety of neoadjuvant sintilimab, oxaliplatin and capecitabine in patients with locally advanced, resectable gastric or gastroesophageal junction adenocarcinoma: early results of a phase 2 study.

Immune checkpoint inhibitors have greatly improved the prognoses of diverse advanced malignancies, including gastric and gastroesophageal junction (G/GEJ) cancer. However, the role of anti-programmed cell death protein-1 treatment in the neoadjuvant setting remains unclear. This phase 2 study aimed to evaluate sintilimab plus CapeOx as a neoadjuvant regimen in patients with advanced resectable G/GEJ adenocarcinoma. Eligible patients with resectable G/GEJ adenocarcinoma stage cT3-4NanyM0 were enrolled. Patients received neoadjuvant treatment with sintilimab (3 mg/kg for cases <60 kg or 200 mg for those ≥60 kg on day 1) plus CapeOx (oxaliplatin at 130 mg/m2 on D1 and capecitabine at 1000 mg/m2 two times per day on D1-D14) every 21 days, for three cycles before surgical resection, followed by adjuvant treatment with three cycles of CapeOx with the same dosages after surgical resection. The primary endpoint was pathological complete response (pCR) rate. Secondary endpoints included objective response rate, tumor regression grade per Becker criteria, survival and safety. As of July 30, 2020, 36 patients were enrolled. Totally 7 (19.4%) patients had GEJ cancer, and 34 (94.4%) patients were clinical stage III cases. A total of 35 (97.2%) patients completed three cycles of neoadjuvant treatment, and 1 patients received two cycles due to adverse events. All patients underwent surgery and the R0 resection rate was 97.2%. In this study, pCR and major pathological response were achieved in 7 (19.4%, 95% CI: 8.8% to 35.7%; 90% CI: 10.7% to 33.1%) and 17 (47.2%, 95% CI: 31.6% to 64.3%) patients, respectively. Thirty-one patients received adjuvant treatment. By December 20, 2021, three patients died after disease relapse, and two patients were alive with relapse. Median disease-free survival (DFS) and overall survival (OS) were not reached. The 1-year DFS and OS rates were 90.3% (95% CI: 80.4% to 100.0%) and 94.1% (95% CI: 86.5% to 100.0%), respectively. The most common (>1 patient) grade 3 treatment-related adverse events during neoadjuvant treatment were anemia and neutropenia (n=5 each, 13.9%). No serious adverse events (AEs) or grade 4-5 AEs were observed. Sintilimab plus oxaliplatin/capecitabine showed promising efficacy with encouraging pCR rate and good safety profile in the neoadjuvant setting. This combination regimen might present a new option for patients with locally advanced, resectable G/GEJ adenocarcinoma. Trial registration; NCT04065282.

Preventative and Therapeutic Effects of Metformin in Gastric Cancer: A New Contribution of an Old Friend.

Gastric cancer (GC) is a cancer with high prevalence, and is one of the leading causes of cancer death worldwide. Metformin is a widely used hypoglycemic agent for type-2 diabetes mellitus (T2DM). Recently, metformin has drawn increasing attention in the field of cancer research for its emerging anti-cancer roles. However, the efficacy and underlying molecular mechanisms of metformin in the prevention and treatment for GC remain controversial. This review summarized the present clinical and mechanistic studies that investigated the efficacy of metformin in GC. It was found that the majority of clinical studies affirmed protective roles of metformin in both gastric cancer risk and survival rate. In addition, metformin's effects in the prevention and treatment for GC involve multiple pathways mainly via AMPK and IGF-1R. It was concluded that metformin presents a unique opportunity for application against GC, but further clinical and mechanistic investigations are required to solidify the roles of metformin in GC.

Establishment of a novel human cell line retaining the characteristics of the original pancreatic adenocarcinoma, and evaluation of MEK as a therapeutic target.

Pancreatic cancer is a lethal solid malignancy with limited therapeutic options. The development of novel therapeutic drugs requires adequate new cell line models. A new pancreatic cancer cell line, designated PDXPC1, was established from one pancreatic ductal adenocarcinoma (PDAC) patient­derived xenograft. The PDXPC1 cells were stably cultured for >2 years and had a stable short tandem repeat profile. The PDXPC1 cell line retained the key mutations of the primary tumor, along with the epithelial origin and other important protein expression. The PDXPC1 cells induced rapid in vivo tumor growth, both subcutaneously and orthotopically, in a mouse model with an elevated CA199 level. The PDXPC1 cells showed weak growth, invasion and migration potency compared to another pancreatic cancer cell line, but were relatively resistant to multiple anti­cancer drugs. Interestingly, the MEK inhibitor trametinib significantly inhibited the proliferation of PDXPC1 cells, and not that of Panc­1 cells, by inactivating MEK/ERK/MYC signaling and activating the apoptotic pathway via Bcl­2 degradation. In conclusion, the PDXPC1 cell line, capturing the major characteristics of the primary tumor, may be a suitable tool for studying the underlying mechanisms of chemo­resistance in PDAC and developing new targeted therapeutic options.

LncRNA MIR4435-2HG targets desmoplakin and promotes growth and metastasis of gastric cancer by activating Wnt/ß-catenin signaling.

Long non-coding RNAs (lncRNAs) have been implicated in the pathogenesis of gastric cancer; however, their mechanisms of action remain largely unknown. The aim of this study was to identify lncRNAs involved in the tumorigenesis of gastric cancer and to investigate the signaling pathways they affect. Using microarray and RT-qPCR analyses, candidate lncRNAs were screened in paired gastric cancer tissues. The analysis revealed MIR4435-2HG to be markedly up-regulated in gastric cancer samples compared to normal stomach specimens. Increased MIR4435-2HG expression was associated with aggressive clinicopathologic features and unfavorable tumor stage. Functional experiments showed that MIR4435-2HG up-regulation enhanced gastric cancer cell proliferation, clonogenicity, and migration and invasion in vitro, as well as tumorigenicity in mice. Using RNA pull-down and mass-spectrometry analyses we found and verified a direct and novel interaction between MIR4435-2HG and desmoplakin (DSP), the most abundant desmosomal protein. Overexpression and knockdown experiments revealed opposing roles for DSP and MIR4435-2HG, unmasking a cascade through which MIR4435-2HG binds to and inhibits DSP, leading to activation of WNT/ß-catenin signaling and epithelial-mesenchymal transition in gastric cancer cells. We propose that the MIR4435-2HG/DSP/WNT axis serves as a critical effector of carcinogenesis and progression of gastric cancer, and could be exploited therapeutically to improve patients' outcomes.

COL12A1, a novel potential prognostic factor and therapeutic target in gastric cancer.

Dysregulation of collagen type XII α1 chain (COL12A1) has been found in several cancer types and could be involved in tumor progression. However, its clinical significance in gastric cancer (GC) remains under exploration. Online databases (Gene Expression Omnibus and UALCAN), reverse transcription­quantitative PCR and immunohistochemistry were utilized in the present study to evaluate the expression of COL12A1 in GC tissues and cell lines. It was found that COL12A1 expression was notably upregulated in GC. Clinicopathological analysis showed that elevated COL12A1 expression was positively correlated with tumor invasiveness, metastasis and advanced clinical stage. The prognostic analysis suggested that high COL12A1 expression contributed to poor overall survival. Multivariate Cox analysis indicated that COL12A1 overexpression was a powerful independent prognostic indicator in patients with GC (hazard ratio, 1.896; 95% CI, 1.267­2.837; P=0.002). The results highlighted the importance of COL12A1 in GC and suggested its potential role as a candidate for clinical outcome prediction and targeted therapy in patients with GC.

Clonal analysis of early-stage bilateral papillary thyroid cancer identifies field cancerization.

INTRODUCTION: Bilaterality is a newly identified indicator for aggressive tumor behavior and poor outcome in papillary thyroid cancer. However, the clonal origin of these bilateral tumors remains unclear. METHODS: Here we analyzed 28 pairs of early-stage papillary thyroid cancers (stage I-II without extra-thyroidal extension, lymph node metastasis or distant metastasis) that underwent surgery at First Affiliated Hospital of Zhejiang University School of Medicine (Hangzhou, China). Genomic DNA was extracted from paraffin-embedded tissues after microdissection and analyzed for BRAF mutation and X-chromosome inactivation. RESULTS: A total of 16 patients (16/28, 57.1%) harbored different BRAF status in bilateral tumors. Fourteen patients were available for X-chromosome inactivation assay and 10 of them achieved informative results. Bilateral tumors from four cases had distinct patterns of X-chromosome inactivation. Combining the results of X-chromosome inactivation and BRAF analysis, we demonstrated that at least 64.3% (18/28) cases harbored discordant X-chromosome inactivation or BRAF status, indicating their independent clonal origin in bilateral tumors. CONCLUSIONS: The present study confirms "field cancerization" in early-stage bilateral thyroid cancers, suggesting that these subtype papillary thyroid cancers should be treated as independent and localized tumors.

LncRNA UCA1 in anti-cancer drug resistance.

The pivotal role of the long non-coding RNA (lncRNA) urothelial carcinoma associated 1 (UCA1) in anti-cancer drug resistance has been confirmed in many cancers. Overexpression of lncRNA UCA1 correlates with resistance to chemotherapeutics such as cisplatin, gemcitabine, 5-FU, tamoxifen, imatinib and EGFR-TKIs, whereas lncRNA UCA1 knockdown restores drug sensitivity. These studies highlight the potential of lncRNA UCA1 as a diagnostic and prognostic biomarker, and a therapeutic target in malignant tumors. In this review, we address the role of lncRNA UCA1 in anti-cancer drug resistance and discuss its potential in future clinical applications.

Lower Beclin 1 downregulates HER2 expression to enhance tamoxifen sensitivity and predicts a favorable outcome for ER positive breast cancer.

Tamoxifen(TAM) is one of the most effective endocrine treatment for estrogen receptor(ER)-positive breast cancer, however drug resistance greatly limits benefit of it. Our purpose is to uncover the role of Beclin 1 in tamoxifen resistance and prognosis of ER positive breast cancer. We established a tamoxifen resistant ER-positive breast cancer cell subline MCF-7R presenting with higher Beclin 1 and human epidermal growth factor receptor 2(HER2) levels than MCF-7. Silencing Beclin 1 decreased levels of HER2 and significantly promoted TAM sensitivity of MCF-7 and MCF-7R in vitro. Overexpression of HER2 could reverse TAM sensitivity, which was formerly increased in Beclin 1 downregulated cell. Beclin 1 level was not only positively correlated with level of HER2 but also negatively correlated with overall survival of ER-positive breast cancer patients. Using bioinformatic methods, Beclin 1 mRNA was found to be negatively correlated with overall survival in breast cancer patients receiving TAM treatment. This study indicated for the first time that lower HER2 expression by Beclin 1 downregulation contributes to alteration of tamoxifen sensitivity and low Beclin 1 predicts favorable outcome in ER-positive breast cancer.

Establishment of patient-derived gastric cancer xenografts: a useful tool for preclinical evaluation of targeted therapies involving alterations in HER-2, MET and FGFR2 signaling pathways.

BACKGROUND: Targeted therapies are emerging treatment options for gastric cancer (GC). Patient-derived tumor xenograft(PDX) models of GC closely retain the features of the original clinical cancer, offering a powerful tool for preclinical drug efficacy testing. This study aimed to establish PDX GC models, and explore therapeutics targeting Her2, MET(cMet), and FGFR2, which may assist doctor to select the proper target therapy for selected patients. METHODS: GC tissues from 32 patients were collected and implanted into immuno-deficient mice. Using immunohistochemistry(IHC) and fluorescent in-situ hybridization (FISH), protein levels and/or gene amplification of Her2, cMet and FGFR2 in those tissues were assessed. Finally, anti-tumor efficacy was tested in the PDX models using targeted inhibitors. RESULTS: A total of 9 passable PDX models were successfully established from 32 gastric cancer xenograft donors, consisting of HER2,cMet and FGFR2 alterations with percentages of 4(12.5%), 8(25.0%) and 1(3.1%) respectively. Crizotinib and AZD4547 exerted marked antitumor effects exclusively in PDX models with cMet (G30,G31) and FGFR2(G03) amplification. Interestingly, synergistic antitumor activity was observed in G03 (FGFR2-amplifed and cMet non-amplified but IHC [2+]) with simultaneous treatment with Crizotinib and ADZ4547 at day 30 post-treatment. Further in vitro biochemistry study showed a synergistic inhibition of the MAPK/ERK pathway. HER2,cMet and FGFR2 alterations were found in 17 (10.4%), 32(19.6%) and 6(3.7%) in a group of 163 GC patients, and cMet gene amplification or protein overexpression(IHC 3+) was associated with poor prognosis. CONCLUSIONS: These PDX GC models provide an ideal platform for drug screening and evaluation. GC patients with positive cMet or FGFR2 gene amplification may potentially benefit from cMet or FGFR2 targeted therapies or combined targeted therapy.

Comparison of the clinicopathologic features and prognosis of bilateral versus unilateral multifocal papillary thyroid cancer: An updated study with more than 2000 consecutive patients.

BACKGROUND: Bilaterality is common in papillary thyroid cancer (PTC), but its clinical and prognostic implications are still controversial, and it remains unclear whether its behavior is more aggressive than multifocality. METHODS: The clinicopathologic features of 2211 consecutive patients with PTC who underwent surgical treatment at the authors' institute between 1997 and 2011 were reviewed. Among these surgical patients, 425 (19.2%) had bilateral PTCs, and 1786 had unilateral PTCs. The patients who had unilateral PTCs were subdivided into a group with unilateral-multifocal PTCs (210 patients) and a group with solitary PTCs (1576 patients). The 10-year disease-free survival (DFS) rates were calculated to compare the prognosis between groups. B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutation status was examined by direct DNA sequencing. RESULTS: Patients who had bilateral PTCs were likely to have larger tumors, higher rates of extrathyroid extension and lymph node metastasis, and more advanced tumor stage than those who had unilateral-multifocal PTCs. Multivariate analysis identified only lymph node metastasis as an independent risk factor for PTC recurrence (P < .001). The 10-year DFS rate for patients with bilateral PTCs was much lower than that for those with unilateral-multifocal and solitary PTCs (78.8% vs 85.7% and 89.3%, respectively; P = .005). It is noteworthy that patients who had bilateral PTCs with lymph node metastasis had the worst prognosis in terms of DFS. Incidence of the BRAF V600E mutation (valine to glutamic acid mutation at position 600) was higher in the bilateral PTC group than that in the unilateral and unilateral-multifocal PTC groups. CONCLUSIONS: The current results provide initial evidence that bilateral PTCs are more aggressive than unilateral-multifocal PTCs, and patients who have bilateral disease have more advanced stage and shorter DFS. The poorer outcome of patients with bilateral PTCs may be caused in part by their high incidence of lymph node metastasis. Cancer 2016;122:198-206. © 2015 American Cancer Society.

Establishment and characterization of GCSR1, a multi-drug resistant signet ring cell gastric cancer cell line.

Signet ring cell gastric cancer (SRCGC) has very poor prognosis worldwide, and studying its molecular characteristics is urgent for improving the outcome. However, few well-characterized SRCGC cell lines are available for research. Therefore, we established a novel cell line GCSR1, from a Chinese male SRCGC patient. Cell morphology of GCSR1 in culture, maintained in vitro for over 90 passages, is similar to the cells from the patient. GCSR1 cells proliferated in vitro with a doubling time of 67.65 h. Karyotyping showed they were aneuploid. Missense mutation occurred in codon 193 of P53 and deletion occurred in exons 1 and 3 of P16. Results of CCK8 assay revealed that GCSR1 was more resistant to 5-fluorouracil (5-FU) and mitomycin (MMC) than other gastric cancer cell lines. Stem cell marker assay by flow cytometry showed that GCSR1 had high proportion of CD44+ and/or CD133+ cells. It formed colonies easily in soft agar and generated xenograft tumors in nude mice. In conclusion, GCSR1 is a well-established, well-characterized multi-drug resistant cell line with abundant cancer stem cells.

Luteolin exerts a marked antitumor effect in cMet-overexpressing patient-derived tumor xenograft models of gastric cancer.

BACKGROUND: Aberrated activation of cMet in gastric cancer contributes to tumor growth, angiogenesis and metastasis. cMet-overexpressing gastric cancer has a poor prognosis because of high tumor metastasis and limited therapeutic options. Luteolin is a common dietary flavonoid with antitumor properties. However, the antitumor effect of luteolin on cMet-overexpressing gastric cancer remain unclear. METHODS: Two cMet-overexpressing patient-derived human tumor xenograft (PDTX) models of gastric cancer were established, and treated with luteolin or vehicle to evaluate the antitumor effects of luteolin. Tumor specimens were subjected to H&E staining and immunohistochemistry. MKN45 and SGC7901 cells that show high cMet expression were treated with varying concentrations of luteolin and evaluated by western blot, cell viability, apoptosis, migration, and invasion assays. RESULTS: Luteolin inhibited the tumor growth in cMet-overexpressing PDTX models. Immunohistochemistry demonstrated that expression of cMet, MMP9 and Ki-67 were significantly down-regulated. Luteolin inhibited proliferation, promoted apoptosis and reduced the invasiveness of MKN45 and SGC7901 cells. Western blot revealed that luteolin promoted the activation of apoptosis-related proteins, caspase-3 and PARP-1, and down-regulated the invasion-associated protein, MMP9. Further studies demonstrated that luteolin decreased the expression and phosphorylation of cMet, and downstream phosphorylation of Akt and ERK. In addition, luteolin down-regulated phosphorylated Akt independently of cMet. Blocking Akt and/or ERK with the PI3K inhibitor, LY294002, or the ERK inhibitor, PD98059, induced down-regulation of MMP9 and up-regulation of cleaved caspase-3 and PARP-1, resembling the effects of luteolin. CONCLUSIONS: Our findings ,for the first time, demonstrate that luteolin exerts marked antitumor effects in cMet-overexpressing PDTX models of gastric cancer, through a mechanism likely involving cMet/Akt/ERK signaling. These findings indicate that luteolin may act as a potential therapeutic option for cMet-overexpressing gastric cancer.

Giant appendiceal neurofibroma in von Recklinghausen's disease: A case report and literature review.

A 62-year-old female with neurofibromatosis type 1 (NF1; also von Recklinghausen's disease) was diagnosed with a giant, thick-walled tubular mass, mainly located in the right abdominal area on computed tomography, following an examination for intermittent abdominal pain and increasing abdominal distension. According to the clinical manifestations and imaging features, the giant tubular mass was considered most likely to be a dilated fallopian tube associated with infection, while the possibility of obstructed bowel loops was excluded. However, the subsequent laparotomy revealed a giant appendix, caused by a large neurofibroma in the root region of the appendix, which occluded the lumen. Neurofibroma of the appendix is extremely rare, even in patients with NF1. To the best of our knowledge, only three such cases have previously been reported in the English literature to date.

Estrogen receptor-α36 is involved in development of acquired tamoxifen resistance via regulating the growth status switch in breast cancer cells.

Acquired tamoxifen (TAM) resistance limits the therapeutic benefit of TAM in patients with hormone-dependent breast cancer. The switch from estrogen-dependent to growth factor-dependent growth is a critical step in this process. However, the molecular mechanisms underlying this switch remain poorly understood. In this study, we established a TAM resistant cell sub line (MCF-7/TAM) from estrogen receptor-α (ER-α66) positive breast cancer MCF-7 cells by culturing ER-α66-positive MCF-7 cells in medium plus 1 µM TAM over 6 months. MCF-7/TAM cells were then found to exhibit accelerated proliferation rate together with enhanced in vitro migratory and invasive ability. And the estrogen receptor-α36 (ER-α36), a novel 36-kDa variant of ER-α66, was dramatically overexpressed in this in vitro model, compared to the parental MCF-7 cells. Meanwhile, the expression of epidermal growth factor receptor (EGFR) in MCF-7/TAM cells was significantly up-regulated both in mRNA level and protein level, and the expression of ER-α66 was greatly down-regulated oppositely. In the subsequent studies, we overexpressed ER-α36 in MCF-7 cells by stable transfection and found that ER-α36 transfected MCF-7 cells (MCF-7/ER-α36) similarly exhibited decreased sensitivity to TAM, accelerated proliferative rate and enhanced in vitro migratory and invasive ability, compared to empty vector transfected MCF-7 cells (MCF-7/V). Real-time qPCR and Western blotting analysis revealed that MCF-7/ER-α36 cells possessed increased EGFR expression but decreased ER-α66 expression both in mRNA level and protein level, compared to MCF-7/V cells. This change in MCF-7/ER-α36 cells could be reversed by neutralizing anti-ER-α36 antibody treatment. Furthermore, knock-down of ER-α36 expression in MCF-7/TAM cells resulted in reduced proliferation rate together with decreased in vitro migratory and invasive ability. Decreased EGFR mRNA and protein expression as well as increased ER-α66 mRNA expression were also observed in MCF-7/TAM cells with down-regulated ER-α36 expression. In addition, blocking EGFR/ERK signaling in MCF-7/ER-α36 cells could restore the expression of ER-α66 partly, suggesting a regulatory function of EGFR/ERK signaling in down-regulation of ER-α66 expression. In conclusion, our results indicated for the first time a regulatory role of ER-α36 in up-regulation of EGFR expression and down-regulation of ER-α66 expression, which could be an underlying mechanism for the growth status switch in breast tumors that contribute to the generation of acquired TAM resistance. And ER-α36 could be considered a potential new therapeutic target in breast tumors which have acquired resistance to TAM.

Antitumor effect of FP3 in a patient-derived tumor tissue xenograft model of gastric carcinoma through an antiangiogenic mechanism.

FP3 (KH902/KH903) is a novel vascular endothelial growth factor (VEGF) blocker with antiangiogenic properties. Previous studies revealed that FP3, a humanized fusion protein that combines ligand binding elements from the extracellular domains of VEGF receptors 1 and 2 and the Fc portion of IgG1, has an inhibitory effect on the VEGF-mediated proliferation and migration of human umbilical vein endothelial cells, and VEGF-mediated vessel sprouting of rat aortic rings in vitro. Thus, FP3 was considered as a new promising agent in treating human choroidal neovascularization (CNV) caused by age-related macular degeneration (AMD). FP3 also has an antitumor effect in a non-small cell lung cancer cell line (A549) xenograft model in nude mice. However, little is known of the direct effects of FP3 on tumor vessels. In this study, we investigated the effects of FP3 on blood vessels in a patient-derived tumor tissue (PDTT) xenograft model of gastric carcinoma, using large tumors with established vasculature. Treatment with FP3 caused robust and early changes in endothelial cells and pericytes of vessels in the PDTT xenograft model. Vascular density decreased and vascular sprouting was suppressed by treatment with FP3. Pericytes did not degenerate to the same extent as endothelial cells, and those on surviving tumor vessels achieved a more normal phenotype. Our results revealed that FP3 has a direct and rapid antiangiogenic effect on tumor vessels, which was achieved mainly via regression of tumor vasculature, inhibition of new and recurrent vessel growth, and normalization of existing tumor vasculature.

Differential response to EGFR- and VEGF-targeted therapies in patient-derived tumor tissue xenograft models of colon carcinoma and related metastases.

Heterogeneity in primary tumors and related metastases may result in failure of antitumor therapies, particularly in targeted therapies for the treatment of cancer. In this study, patient-derived tumor tissue (PDTT) xenograft models of colon carcinoma with lymphatic and hepatic metastases were used to evaluate the response to EGFR- and VEGF-targeted therapies. Our results showed that primary colon carcinoma and its corresponding lymphatic and hepatic metastases have a different response rate to anti-EGFR (cetuximab) and anti-VEGF (bevacizumab) therapies. However, the underlying mechanism of these types of phenomenon is still unclear. To investigate whether such phenomena may result from the heterogeneity in primary colon carcinoma and related metastases, we compared the expression levels of cell signaling pathway proteins using immunohistochemical staining and western blotting, and the gene status of KRAS using pyrosequencing in the same primary colon carcinoma and its corresponding lymphatic and hepatic metastatic tissues which were used for establishing the PDTT xenograft models. Our results showed that the expression levels of EGFR, VEGF, Akt/pAkt, ERK/pERK, MAPK/pMAPK, and mTOR/pmTOR were different in primary colon carcinoma and matched lymphatic and hepatic metastases although the KRAS gene status in all cases was wild-type. Our results indicate that the heterogeneity in primary colon carcinoma and its corresponding lymphatic and hepatic metastases may result in differences in the response to dual-inhibition of EGFR and VEGF.

Antitumor effects of FP3 in combination with capecitabine on PDTT xenograft models of primary colon carcinoma and related lymphatic and hepatic metastases.

FP3 is an engineered protein which contains the extracellular domain 2 of VEGF receptor 1 (Flt-1) and extracellular domain 3 and 4 of VEGF receptor 2 (Flk-1, KDR) fused to the Fc portion of human immunoglobulin G 1. Previous studies demonstrated its antiangiogenic effects in vitro and in vivo, and its antitumor activity in vivo. In this study, patient-derived tumor tissue (PDTT) xenograft models of primary colon carcinoma and lymphatic and hepatic metastases were established for assessment of the antitumor activity of FP3 in combination with capecitabine. Xenografts were treated with FP3, capecitabine, alone or in combination. After tumor growth was confirmed, volume and microvessel density in tumors were evaluated. Levels of VEGF, and PCNA in the tumor were examined by immunohistonchamical staining, level of thymidine phosphorylase (TP) was examined by ELISA, and levels of related cell signaling pathways proteins expression were examined by western blotting. FP3 in combination with capecitabine showed significant antitumor activity in three xenograft models (primary colon carcinoma, lymphatic metastasis, and hepatic metastasis). The microvessel density in tumor tissues treated with FP3 in combination with capecitabine was lower than that of the control. Antitumor activity of FP3 in combination with capecitabine was significantly higher than that of each agent alone in three xenograft models (primary colon carcinoma, lymphatic metastasis, and hepatic metastasis). This study indicated that addition of FP3 to capecitabine significantly improved tumor growth inhibition in the PDTT xenograft models of primary colon carcinoma and lymphatic and hepatic metastases.

The effect of anti-VEGF drugs (bevacizumab and aflibercept) on the survival of patients with metastatic colorectal cancer (mCRC).

Significant progression has been achieved in the treatment of metastatic colorectal cancer (mCRC) in recent years. This has been partly attributed to successfully incorporating new drugs into combination chemotherapy. In addition to the traditional cytotoxic chemotherapeutic agents, molecularly targeted agents began to play an important role in the treatment of advanced solid tumors. To date, two classes of molecularly targeted agents have been approved for treatment of patients with mCRC: (1) antivascular endothelial growth factor (anti-VEGF) agents (such as bevacizumab and aflibercept) and (2) antiendothelial cell growth factor receptor (anti-EGFR) agents (such as cetuximab and panitumumab). Aflibercept is a new member of anti-VEGF agents which has demonstrated efficacy for treatment of mCRC. With the commencement of clinical trials and basic research into aflibercept, more data from the bedside and the bench have been obtained. This review will outline the application of anti-VEGF agents by reviewing clinic experiences of bevacizumab and aflibercept, and try to add perspectives on the use of anti-VEGF agents in mCRC.

Anti-angiogenic therapy for colorectal cancer: on the way to getting better!

Based on the theory that tumor growth and metastasis depend on vessels to provide oxygen and nutrients, antiangiogenic therapy was thought as a promising approach to cure cancer. Bevacizumab is the first validated angiogenesis inhibitor, when combined with conventional treatments, which can enhance antitumor effects and prolong survival for patients with colorectal cancer. However, recent years, bevacizumab and other angiogenesis inhibitors are more discussed with drug resistance and the diverse test results. Fortunately, antiangiogenic strategy is more than bevacizumab and more than anti-vascular endothelial growth factor. Dozens of compounds that potently inhibit neoplastic blood vessels formation with different mechanisms have been developed, and many of them are being tested clinically for colorectal cancer. This review will numerate the principal antiangiogenic drugs with various mechanisms, recapitulate the information of studying these drugs for colorectal cancer treatment and try to clue better usage of antiangiogenic therapy for patients with colorectal cancer in the future.