Therapeutic targeting of integrin αvß6 in breast cancer.

BACKGROUND: Integrin αvß6 promotes migration, invasion, and survival of cancer cells; however, the relevance and role of αvß6 has yet to be elucidated in breast cancer. METHODS: Protein expression of integrin subunit beta6 (ß6) was measured in breast cancers by immunohistochemistry (n > 2000) and ITGB6 mRNA expression measured in the Molecular Taxonomy of Breast Cancer International Consortium dataset. Overall survival was assessed using Kaplan Meier curves, and bioinformatics statistical analyses were performed (Cox proportional hazards model, Wald test, and Chi-square test of association). Using antibody (264RAD) blockade and siRNA knockdown of ß6 in breast cell lines, the role of αvß6 in Human Epidermal Growth Factor Receptor 2 (HER2) biology (expression, proliferation, invasion, growth in vivo) was assessed by flow cytometry, MTT, Transwell invasion, proximity ligation assay, and xenografts (n ≥ 3), respectively. A student's t-test was used for two variables; three-plus variables used one-way analysis of variance with Bonferroni's Multiple Comparison Test. Xenograft growth was analyzed using linear mixed model analysis, followed by Wald testing and survival, analyzed using the Log-Rank test. All statistical tests were two sided. RESULTS: High expression of either the mRNA or protein for the integrin subunit ß6 was associated with very poor survival (HR = 1.60, 95% CI = 1.19 to 2.15, P = .002) and increased metastases to distant sites. Co-expression of ß6 and HER2 was associated with worse prognosis (HR = 1.97, 95% CI = 1.16 to 3.35, P = .01). Monotherapy with 264RAD or trastuzumab slowed growth of MCF-7/HER2-18 and BT-474 xenografts similarly (P < .001), but combining 264RAD with trastuzumab effectively stopped tumor growth, even in trastuzumab-resistant MCF-7/HER2-18 xenografts. CONCLUSIONS: Targeting αvß6 with 264RAD alone or in combination with trastuzumab may provide a novel therapy for treating high-risk and trastuzumab-resistant breast cancer patients.

Primary chemotherapy for inoperable ovarian, fallopian tube, or primary peritoneal cancer with or without delayed debulking surgery.

OBJECTIVE: To describe the outcome of primary chemotherapy for women with advanced-stage epithelial ovarian or primary peritoneal cancer and delayed surgery when optimal debulking surgery cannot be achieved at diagnosis. METHODS: Between 1998 and 2006, we retrospectively reviewed the overall survival and examined prognostic markers in consecutive patients who were not suitable for initial radical surgery because of the extent of disease and/or poor performance status. They were treated with a policy of primary platinum-based chemotherapy, followed whenever possible in responding patients by debulking surgery. RESULTS: A total of 171 patients received least one cycle of chemotherapy. Eighty-six patients proceeded to surgery and 53 (31% of 171 and 62% of 86) had optimal (<1 cm) residual disease. Eighty-five patients did not undergo surgery because they remained unfit or had not responded sufficiently to chemotherapy. The median overall survival was 18.7 months (95% confidence interval [CI], 16.5-24.2). The median OS in the surgical group for optimal and suboptimal surgery was 40.8 (95% CI, 32.5-50.0) and 22.5 (95% CI, 17.7-37.1) months (P = 0.005). On multivariate analysis, interval surgery and optimal surgery were the only independent prognostic factors (hazard ratios, 0.45 and 0.43, respectively; P = 0.009). In the nonsurgical group, CA125 response was an independent prognostic factor (hazard ratio, 0.34; P = 0.001) with an OS of 21.7 months (95% CI, 14.0-35.4) in women with a normal CA125 after treatment compared with 6.7 (95% CI, 4.5-7.8) months. CONCLUSIONS: In one third of the women, the tumor was optimally debulked after primary chemotherapy and their median survival was 40.8 months. Suboptimal debulking surgery after primary chemotherapy did not result in a better survival than that achieved after a chemotherapy response alone, suggesting that surgery may be avoided when imaging after chemotherapy demonstrates residual disease that cannot be optimally debulked.

High-resolution in vivo imaging of breast cancer by targeting the pro-invasive integrin alphavbeta6.

The integrin alphavbeta6 is expressed only on epithelia and then usually only during processes of tissue remodelling including cancer, where its high expression correlates with reduced survival. Thus, alphavbeta6 represents an important target for imaging and therapy of cancer and new molecular-specific targeting agents are required. We have developed A20FMDV2, a peptide derived from the VP1 coat protein of foot-and-mouth-disease virus that binds specifically and stably to alphavbeta6. Using a newly generated pair of isogenic human cell lines that differ only in alphavbeta6 expression, it was shown, using biodistribution and SPECT imaging, that indium-111-labelled A20FMDV2 locates specifically to alphavbeta6-expressing tissues in vivo, achieving at least seven-times higher retention in alphavbeta6-positive than in alphavbeta6-negative tumours. In further studies with MCF10.DCIS.COM and MCF10A.CA1a breast carcinoma cell lines, which express alphavbeta6 endogenously, the radiopeptide achieved similar levels of tumour retention and permitted excellent discriminatory imaging of tumours. Thus, A20FMDV2 can be used for molecular-specific targeting of alphavbeta6 for imaging in vivo the often more aggressive, alphavbeta6-positive cancers. In the future, A20FMDV2 could serve also to deliver therapy to these same cancers.

In vivo retargeting of adenovirus type 5 to alphavbeta6 integrin results in reduced hepatotoxicity and improved tumor uptake following systemic delivery.

A key impediment to successful cancer therapy with adenoviral vectors is the inefficient transduction of malignant tissue in vivo. Compounding this problem is the lack of cancer-specific targets, coupled with a shortage of corresponding high-efficiency ligands, permitting selective retargeting. The epithelial cell-specific integrin alphavbeta6 represents an attractive target for directed therapy since it is generally not expressed on normal epithelium but is upregulated in numerous carcinomas, where it plays a role in tumor progression. We previously have characterized a high-affinity, alphavbeta6-selective peptide (A20FMDV2) derived from VP1 of foot-and-mouth disease virus. We generated recombinant adenovirus type 5 (Ad5) fiber knob, incorporating A20FMDV2 in the HI loop, for which we validated the selectivity of binding and functional inhibition of alphavbeta6. The corresponding alphavbeta6-retargeted virus Ad5-EGFP(A20) exhibited up to 50-fold increases in coxsackievirus- and-adenovirus-receptor-independent transduction and up to 480-fold-increased cytotoxicity on a panel of alphavbeta6-positive human carcinoma lines compared with Ad5-EGFP(WT). Using an alphavbeta6-positive (DX3-beta6) xenograft model, we observed a approximately 2-fold enhancement in tumor uptake over Ad5-EGFP(WT) following systemic delivery. Furthermore, approximately 5-fold-fewer Ad5-EGFP(A20) genomes were detected in the liver (P = 0.0002), correlating with reduced serum transaminase levels and E1A expression. Warfarin pretreatment, to deplete coagulation factors, did not improve tumor uptake significantly with either virus but did significantly reduce liver sequestration and hepatic toxicity. The ability of Ad5-EGFP(A20) to improve delivery to alphavbeta6, combined with its reduced hepatic tropism and toxicity, highlights its potential as a prototype virus for future clinical investigation.

Gemcitabine and carboplatin: is this the best combination for non-small cell lung cancer?

Approximately 30-40% of non-small cell lung cancer patients will present with metastatic disease, and its associated poor prognosis. Chemotherapy has an established palliative role within late-stage disease, but is also being used increasingly in the neoadjuvant and adjuvant settings. Platinum-based chemotherapy has been shown to produce definite improvements in efficacy and quality of life in non-small cell lung cancer patients, and is now the standard of care. Carboplatin has similar biochemical properties to those of cisplatin. However, carboplatin has much less renal, otologic, neurologic and upper gastrointestinal toxicities than cisplatin, and treatment can be conveniently delivered in an out-patient setting. Furthermore, platinum combinations with third-generation cytotoxics have shown additional gains in survival rates. Gemcitabine and carboplatin is a well-tolerated regime. Recent meta- and cost analyses have discovered that gemcitabine-based regimes may have an advantage over other third-generation agent platinum combinations. This article reviews the evidence demonstrating that gemcitabine-carboplatin is effective, convenient and cost effective.