Kathryn Compton

Comparative analysis of monocytic and granulocytic myeloid-derived suppressor cell subsets in patients with gastrointestinal malignancies

Myeloid-derived suppressor cells (MDSC) are a heterogenous population of cells comprising myeloid progenitor cells and immature myeloid cells, which have the ability to suppress the effector immune response. In humans, MDSC have not been well characterized owing to the lack of specific markers, although it is possible to broadly classify the MDSC phenotypes described in the literature as being predominantly granulocytic (expressing markers such as CD15, CD66, CD33) or monocytic (expressing CD14). In this study, we set out to perform a direct comparative analysis across both granulocytic and monocytic MDSC subsets in terms of their frequency, absolute number, and function in the peripheral blood of patients with advanced GI cancer. We also set out to determine the optimal method of sample processing given that this is an additional source of heterogeneity. Our findings demonstrate consistent changes across sample processing methods for monocytic MDSC, suggesting that reliance upon cryopreserved PBMC is acceptable. Although we did not see an increase in the population of granulocytic MDSC, these cells were found to be more suppressive than their monocytic counterparts.

Preclinical and correlative studies of cabozantinib (XL184) in urothelial cancer (UC).

314 Background: Mounting evidence supports Met as a target in urothelial cancer (UC). Activated Met can promote angiogenesis and tumor growth by upregulating VEGF and may play a role in UC pathogenesis. Cabozantinib inhibits both VEGFR2 and Met pathways. In this study, we assessed shed Met (sMet) levels in the urine and serum of UC patients (pts) and cabozantinibs effects on HGF-driven UC cell growth and invasion. METHODS sMet levels in serum and urine samples from 31 pts with UC (23 metastatic, 8 muscle-invasive) were correlated with stage, presence of visceral metastases and urinary source. The effects of cabozantinib on 4 human UC-derived cell lines were studied in vitro. Intact RT4, TCC-SUP, T24M2 and T24M3 cells at 80% confluence were serum deprived 16 h, then left untreated or treated with hepatocyte growth factor (HGF) and/or cabozantinib prior to analysis of Met, phospho- (p)Met, pAkt, Akt, pMAPK and MAPK by immunoassay or immunoblotting. Cabozantinib effects on basal and HGF-induced UC cell invasion, proliferation and soft agar growth were measured. RESULTS Median serum Met levels were modestly higher in pts with metastatic versus muscle-invasive disease. Urinary Met levels were clearly higher in pts with visceral metastasis (p=0.0111) and in urine from ileal conduits and neobladders compared to normally voided urine, regardless of stage (p=0.0489). Met content in UC cell lines was low in RT4 and higher in T24M2, T24M3 and TCC-SUP. Basal pMet content was universally low, increased significantly by HGF and this was reversed by cabozantinib. HGF-driven increases in pAkt/Akt and pMAPK/MAPK in all 4 cell lines were reversed by cabozantinib, as were HGF-enhanced UC cell invasion, proliferation and anchorage independent growth. CONCLUSIONS Median urinary sMet is significantly higher in pts with visceral metastasis and in specimens from ileal conduits and neobladders relative to normally voided urine. UC cell Met content in culture increased with disease grade; HGF stimulated activation of Met and known effectors, and enhanced invasion, growth rate and anchorage-independent growth; cabozantinib effectively reversed these HGF-driven effects. These data support evaluation of cabozantinib in pts with metastatic UC.

Urinary aHGF, IGFBP3 and OPN as diagnostic and prognostic biomarkers for prostate cancer

AIM Serum PSA screening for prostate cancer (PCa) is controversial. Here, we identify three urinary biomarkers - aHGF, IGFBP3 and OPN - for PCa screening and prognostication. METHODS Urinary aHGF, OPN and IGFBP3 from healthy men (n = 19) and men with localized (n = 65) and metastatic (n = 36) PCa were quantified via ELISA. Mann-Whitney nonparametric t-test and the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analyses were used to analyze associations. RESULTS Mean aHGF and IGFBP3 levels were significantly elevated in PCa patients versus controls (p = 0.0006 and p = 0.0012, respectively), and the area under the curve of the receiver operating characteristic curve (indicator of diagnostic accuracy) for aHGF and IGFBP3 was 0.75 and 0.74, respectively. OPN levels were significantly higher in metastatic groups (p = 0.0060) versus localized and controls (area under the curve = 0.68). CONCLUSION Urinary aHGF and IGFBP3 exhibit the capacity for diagnostic discrimination for PCa, whereas OPN may indicate presence of metastatic disease.

Paired tumor biopsy analysis and safety data from a pilot study evaluating Tremelimumab - a monoclonal antibody against CTLA-4 - in combination with ablative therapy in patients with hepatocellular carcinoma (HCC)

Meeting abstracts Tremelimumab is a fully human monoclonal antibody that binds to CTLA-4 expressed on the surface of activated T lymphocytes and results in inhibition of B7-CTLA-4-mediated down regulation of T cell activation. Both transcatheter arterial chemoembolization (TACE) and radiofrequency

Urinary-activated HGF as a noninvasive biomarker for the diagnosis of prostate cancer.

e15144 Background: Hepatocyte growth factor or scatter factor has been linked to the proliferation, motility, and metastatic invasion of cancer cells. Pro-HGF, an inactive precursor, is cleaved into a biologically active heterodimeric form called activated HGF (AHGF). We evaluated the potential of AHGF as a diagnostic and prognostic urinary biomarker candidate for prostate cancer. METHODS Urinary levels of AHGF were determined via enzyme linked immunosorbent assay (Immuno-Biological Laboratories Co., Ltd, Japan) in duplicate. Samples were compared between men with localized (n=65) and metastatic (n=36) cancer and a healthy control group of men (n=19). AHGF concentrations were normalized with creatinine (Bayer DCA 2000+ Analyzer). RESULTS The difference of urinary AHGF levels between the control group (mean: 111.3 pg/mg, range: 27.0-250.0) and the prostate cancer groups (mean: 230.1 pg/mg, range: 20.9-1010.0) was statistically significant (p<0.0001). Furthermore, urinary AHGF concentrations were significantly different between the control and the localized group (mean: 235.2 pg/mg, range: 24.6-668.0) (p<0.0001) and between the control and the metastatic group (mean: 220.8 pg/mg, range: 20.9-1010.0) (p=0.0039). The area under the receiver operating characteristic curve associated with the diagnostic accuracy of HGF between control and prostate cancer groups was 0.75 (p=0.0006, 0.64 to 0.85 confidence interval). There was no significant difference between the localized and metastatic groups. CONCLUSIONS Urinary levels of activated HGF have the potential as a novel noninvasive diagnostic marker for prostate cancer.