Neoadjuvant platelet derived growth factor receptor inhibitor therapy combined with docetaxel and androgen ablation for high risk localized prostate cancer.

PURPOSE: Platelet derived growth factor receptor inhibitor therapy improves the efficacy of taxane chemotherapy in preclinical models of prostate cancer. Men with high risk localized prostate cancer were treated with platelet derived growth factor receptor inhibitor therapy, docetaxel and hormone ablation in the preoperative setting, and clinicopathological outcomes were evaluated. MATERIALS AND METHODS: A total of 36 men with cT2 or greater disease, Gleason grade 8-10, serum prostate specific antigen more than 20 ng/ml or cT2b and prostate specific antigen more than 10 ng/ml and Gleason 7 disease, without radiological evidence of metastases, were scheduled to receive intramuscular leuprolide, 600 mg daily oral imatinib and 30 mg/m(2) weekly docetaxel x 4 every 42 days for 3 cycles before radical prostatectomy (beta [0.02, 1.98] prior on the possibility of pathological complete remission). Unresectable disease, postoperative prostate specific antigen 0.2 ng/ml or greater, or administration of postoperative radiation or hormones were defined as treatment failure. RESULTS: A total of 39 men were registered over 15 months. Median patient age was 57 years (range 44 to 71). Risk factors included T3 disease (22 of 39), Gleason 8-10 disease (31 of 39) and prostate specific antigen more than 20 ng/ml (12 of 39). Three men were ineligible or declined therapy, 29 of 36 (81%) received 3 cycles of therapy and 7 of 36 (19%) discontinued therapy related to toxicity. Grades 3-4 toxicity included rash (4), diarrhea (4), fatigue (6) and neutropenia (1). The surgical approach was feasible, without excessive or unusual complications such as wound dehiscence. No pathological complete remissions were defined. At a median followup of 39 months 53% were free from progression. CONCLUSIONS: Evidence for a favorable impact of platelet derived growth factor receptor inhibitor therapy on the efficacy of neoadjuvant docetaxel and hormonal ablation in high risk localized prostate cancer was not obtained.

Porous silicon nanocarriers for dual targeting tumor associated endothelial cells and macrophages in stroma of orthotopic human pancreatic cancers.

Pancreatic cancer is a highly fatal disease characterized by a dominant stroma formation. Exploring new biological targets, specifically those overexpressed in stroma cells, holds significant potential for the design of specific nanocarriers to attain homing of therapeutic and imaging agents to the tumor. In clinical specimens of pancreatic cancer, we found increased expression of CD59 in tumor associated endothelial cells as well as infiltrating cells in the stroma as compared to uninvolved pancreas. We explored this dual targeting effect using orthotopic human pancreatic cancer in nude mice. By immunofluorescence analysis, we confirmed the increased expression of Ly6C, mouse homolog of CD59, in tumor associated endothelial cells as well as in macrophages within the stroma. We decorated the surface of porous silicon nanocarriers with Ly6C antibody. Targeted nanocarriers injected intravenously accumulated to tumor associated endothelial cells within 15min. At 4h after administration, 9.8±2.3% of injected dose/g tumor of the Ly6C targeting nanocarriers accumulated in the pancreatic tumors as opposed to 0.5±1.8% with non-targeted nanocarriers. These results suggest that Ly6C (or CD59) can serve as a novel dual target to deliver therapeutic agents to the stroma of pancreatic tumors.

Identification and validation of SRC and phospho-SRC family proteins in circulating mononuclear cells as novel biomarkers for pancreatic cancer.

There is an urgent need to develop novel markers of pancreatic cancer to facilitate early diagnosis. Pancreatic carcinoma is characterized by marked stroma formation with a high number of infiltrating tumor-associated macrophages (TAMs) that originate from circulating mononuclear cells (MNCs). We hypothesized that differential analysis of protein expression and phosphorylation in circulating MNCs from healthy nude mice and nude mice bearing orthotopic human pancreatic cancer would identify a surrogate marker of pancreatic cancer. These differences were analyzed by two-dimensional gel electrophoresis followed by Western blot analysis using antibody against phosphorylated tyrosine proteins (pY). Protein and phosphorylated protein spots of interest were identified by mass spectrometry and validated by Western blot analysis as candidate markers for pancreatic cancer. We found that the expression and phosphorylation of Src family proteins were significantly higher in circulating MNCs from mice bearing pancreatic cancer than in circulating MNCs from healthy mice. TAMs in mice with pancreatic tumors also had higher Src family protein expression and phosphorylation than resident macrophages in the pancreas of healthy mice. The expression and phosphorylation of Src family proteins were correlated with tumor weight; however, increased Src expression and phosphorylation also occurred in MNCs from mice with chronic pancreatitis. This is the first report to explore novel pancreatic tumor markers in circulating MNCs. Although the specificity of the marker for pancreatic cancer was low, it could be used to monitor the disease or to select high-risk patients with chronic pancreatitis.

Upregulated stromal EGFR and vascular remodeling in mouse xenograft models of angiogenesis inhibitor-resistant human lung adenocarcinoma.

Angiogenesis is critical for tumor growth and metastasis, and several inhibitors of angiogenesis are currently in clinical use for the treatment of cancer. However, not all patients benefit from antiangiogenic therapy, and those tumors that initially respond to treatment ultimately become resistant. The mechanisms underlying this, and the relative contributions of tumor cells and stroma to resistance, are not completely understood. Here, using species-specific profiling of mouse xenograft models of human lung adenocarcinoma, we have shown that gene expression changes associated with acquired resistance to the VEGF inhibitor bevacizumab occurred predominantly in stromal and not tumor cells. In particular, components of the EGFR and FGFR pathways were upregulated in stroma, but not in tumor cells. Increased activated EGFR was detected on pericytes of xenografts that acquired resistance and on endothelium of tumors with relative primary resistance. Acquired resistance was associated with a pattern of pericyte-covered, normalized revascularization, whereas tortuous, uncovered vessels were observed in relative primary resistance. Importantly, dual targeting of the VEGF and EGFR pathways reduced pericyte coverage and increased progression-free survival. These findings demonstrated that alterations in tumor stromal pathways, including the EGFR and FGFR pathways, are associated with, and may contribute to, resistance to VEGF inhibitors and that targeting these pathways may improve therapeutic efficacy. Understanding stromal signaling may be critical for developing biomarkers for angiogenesis inhibitors and improving combination regimens.