Phenformin as prophylaxis and therapy in breast cancer xenografts

BACKGROUND

Observations that diabetics treated with biguanide drugs have a reduced risk of developing cancer have prompted an enthusiasm for these agents as anti-cancer therapies. We sought to determine the efficacy of the biguanide phenformin in the chemoprophylaxis and in the treatment of oestrogen receptor (ER)-positive MCF7 and receptor triple-negative MDAMB231 xenografts in immunocompromised mice. We also compared the efficacy of phenformin and metformin in the treatment of MDAMB231.

METHODS

Immunocompromised mice were divided into groups: (1) phenformin administered for 2 weeks prior to cell injection; (2) established tumours treated with phenformin; (3) established tumours treated with metformin (only for MDAMB231 tumours); (4) untreated controls. Post-treatment tumours, liver and spleen were harvested for further analysis.

RESULTS

Phenformin significantly inhibited both the development and growth of MCF7 and MDAMB231 tumours, and for MDAMB231 at greater efficacy than metformin without murine toxicity. The number of mitotic figures was significantly fewer in xenografts treated with phenformin compared with controls. Results suggested that the mechanism of action of phenformin in vivo is consistent with AMPK activation.

CONCLUSION

Phenformin has clinical potential as an antineoplastic agent and should be considered for clinical trials both in ER-positive and triple-negative breast cancer.

P3-12-04: Involved Anterior Margins after Breast Conserving Surgery: Is Re-Excision Required?

Background: Complete tumour excision in breast conserving surgery (BCS) is critical for successful treatment; involved circumferential resection margins are associated with increased disease recurrence. However, the importance of an involved anterior margin is less clear. The purpose of this study was to audit an aggressive approach to involved anterior margins and hence assess whether anterior margin re-excision yields clinical benefit.

Material and Methods: A retrospective case note and pathology review was performed for all patients who underwent BCS between 2006 and 2010 through a single cancer centre. An involved margin was defined as <1mm clearance of invasive or in situ breast cancer. Results: 1667 patients underwent BCS for invasive and/or in-situ disease, of whom 114 (6.8%) underwent re-excision, most commonly for mixed invasive and in-situ pathology. The annual re-excision rate rose significantly (p<0.001), with no change in whole tumour diameter, specimen weight or specimen volume. A total of 170 involved margins were identified: most commonly the anterior margin (59 margins, 30.6%) followed by the posterior (39 22.9%) or inferior (31, 18.3%) margin. Patients with anterior margin involvement were more likely to have grade 3 invasive disease (p=0.0323) but less likely to have residual disease found at re-excision (2/49 vs. 32/101 margins, p=0.0033); there were no differences when in-situ characteristics were compared.

Conclusions: Re-excision of involved anterior margins rarely excises residual disease and may be unnecessary. Multidisciplinary teams should consider whether further therapy for an involved anterior margin is required on a patient by patient basis.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-12-04.

P4-02-06: Progesterone Receptor Expression Predicts Poor Outcome in Estrogen Receptor Positive, Lymph Node Negative Breast Cancer – A Population Based Study

Background: Estrogen receptor (ER) positive, lymph node (LN) negative breast cancer usually carries a good prognosis; endocrine therapy is often the only adjuvant treatment. However, a small proportion of such patients do badly (possibly representing those with luminal B cancers identified by gene expression profiling). A clinically applicable method for identifying this subgroup of poor prognosis ER+, LN- patients is required to offer them more intensive adjuvant therapy.

Material and methods: A consecutive, unselected series of 1072 new, operable breast cancer patients diagnosed between 2000 and 2004 was studied for ER and progesterone receptor (PR) expression, HER2 status and standard pathological and demographic parameters. ER and PR expression were scored on immunohistochemistry (IHC) on preoperative, diagnostic core biopsies using the “Quickscore” method. This ensured optimal fixation and tissue processing avoiding the variable fixation of resection specimens and the well-described sampling error of tissue micro-array (TMA) methodologies. PR expression is frequently heterogeneous resulting in false negative scores in at least 12% of cases by TMA analysis. HER2 status was assessed using IHC with dual color FISH for cases scoring 2+. Adjuvant therapy was prescribed using standard protocols; all patients with ER+ disease received adjuvant endocrine therapy. Follow up data were obtained from the oncology database, and the registrar of deaths for the date and cause of death. All deaths not attributable to breast cancer were censored at the date of death. Accordingly, the primary end-point was breast cancer-specific overall survival. Survival analysis was carried out by Kaplan-Meier survival curves analysed by the Log-Rank test. Multivariate analysis was carried out using Cox's regression.

Results: Overall, PR- cancers had a worse prognosis than PR+ (p<10−12, Hazard Ratio 3.40), even in the ER+ (p=0.006, HR 1.86), LN- (p=10−8, HR=5.33) and LN+ (p=10−11, HR=3.26) sub-groups. In the ER+ LN- group, the absence of PR expression predicted worse prognosis (88% vs 96% 8 year survival, p=0.0003) with a hazard ratio of 3.75. This is considerably more significant than Ki67 IHC scoring reported for a similar group of patients in other studies (HR 2.22). Multivariate analysis demonstrated that PR expression was an independent prognostic variable second only to LN status and more powerful than ER.

Discussion: Patients with ER+, LN-, PR- breast cancers have a significantly worse prognosis than those with ER+, LN-, PR+ cancers. Unlike Ki67, PR IHC uses a simple, cost effective, standard methodology (as for ER) and should identify patients who may require chemotherapy in addition to endocrine therapy in this group of otherwise good prognosis patients.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-02-06.

The impact of operative approach for oesophageal cancer on outcome: the transhiatal approach may influence circumferential margin involvement

AIM

Surgery for oesophageal cancer remains the only means of cure for invasive tumours. It is claimed that the surgical approach for these cancers impacts on morbidity and may influence the ability to achieve tumour clearance and therefore survival, however there is no conclusive evidence to support one approach over another. This study aims to determine the impact of operative approach on tumour margin involvement and survival.

METHODS

Data were extracted from the Scottish Audit of Gastric and Oesophageal Cancer (SAGOC), a prospective population-based audit of all oesophageal and gastric cancers in Scotland between 1997 and 1999 with a minimum of five-year follow up. Analysis focused on the three commonest approaches (Ivor Lewis n = 140, transhiatal n = 68, left thoraco-laparotomy n = 142) for oesophageal cancer.

RESULTS

Operative approach had no significant impact on post-operative morbidity, mortality, overall margin involvement and survival. Transhiatal approach resulted in significantly more circumferential margin involvement (p = 0.019), and the presence of circumferential margin involvement significantly reduced five-year survival (median survival 13 months) compared to no margin involvement (median survival 25 months, p = 0.001).

CONCLUSION

Surgical approach for oesophageal cancer had no significant effect on morbidity, post-operative mortality and five-year survival. Non-selective use of the transhiatal approach is associated with a significantly greater circumferential margin involvement, with positive circumferential margin impacting adversely on 5-year survival.

Integrative mRNA profiling comparing cultured primary cells with clinical samples reveals PLK1 and C20orf20 as therapeutic targets in cutaneous squamous cell carcinoma

Identifying therapeutic targets for cancer treatment relies on consistent changes within particular types or sub-types of malignancy. The ability to define either consistent changes or sub-types of malignancy is often masked by tumor heterogeneity. To elucidate therapeutic targets in cutaneous squamous cell carcinoma (cSCC), the most frequent skin neoplasm with malignant potential, we have developed an integrated approach to gene expression profiling beginning with primary keratinocytes in culture. Candidate drivers of cSCC development were derived by first defining a set of in vitro cancer genes and then comparing their expression in a range of clinical data sets containing normal skin, cSCC and the benign hyper-proliferative condition psoriasis. A small interfering RNA (siRNA) screen of the resulting 21 upregulated genes has yielded targets capable of reducing xenograft tumor volume in vivo. Small-molecule inhibitors for one target, Polo-like kinase-1 (PLK1), are already in clinical trials for other malignancies, and our data show efficacy in cSCC. Another target, C20orf20, is identified as being overexpressed in cSCC, and siRNA-mediated knockdown induces apoptosis in vitro and reduces tumor growth in vivo. Thus, our approach has shown established and uncharacterized drivers of tumorigenesis with potent efficacy as therapeutic targets for the treatment of cSCC.

A zinc-containing intraruminal device for prevention of the sporidesmin-induced cholangiopathy of facial eczema in calves

AIM

To develop and evaluate a zinc-containing intraruminal controlled-release bolus for protection of calves (175-250 kg bodyweight) against facial eczema (FE).

METHODS

Boluses releasing zinc, in the form of zinc oxide, at rates ranging from 1.67 to 4.25 g/day were administered to calves which were challenged 4 weeks later with the FE toxin, sporidesmin. The efficacy of the boluses in protecting against sporidesmin-induced cholangiopathy was determined by measuring serum activities of gamma-glutamyltransferase (GGT).

RESULTS

A bolus releasing zinc at approximately 4.25 g/day gave excellent protection against sporidesmin toxicity for periods of up to 5 weeks duration.

CONCLUSIONS

This zinc-containing intraruminal controlled-release bolus has the potential to markedly reduce the incidence and severity of FE in calves within a 175-250 kg bodyweight range.

Evaluation of intraruminal devices for combined facial eczema control and trace element supplementation in sheep

Intraruminal devices containing zinc oxide are very effective in preventing facial eczema in sheep. In the present study such devices augmented with various amounts of selenium and cobalt have been evaluated for their ability to improve the Se and CO status of pregnant ewes, as reflected by changes in blood Se and serum Vitamin B12 concentrations. Devices containing 16.4 mg of Se (as sodium selenate) and 20.4 mg of Co (as cobalt sulphate) were effective in increasing and maintaining elevated blood Se concentrations for at least 84 days and serum Vitamin B12 for 42 days. Such devices will therefore prevent trace element deficiencies in sheep as well as providing protection against facial eczema.

Non-soy legume consumption lowers cholesterol levels: a meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Studies evaluating the effect of legume consumption on cholesterol have focused on soybeans, however non-soy legumes, such as a variety of beans, peas, and some seeds, are commonly consumed in Western countries. We conducted a meta-analysis of randomized controlled trials evaluating the effects of non-soy legume consumption on blood lipids.

METHODS AND RESULTS

Studies were retrieved by searching MEDLINE (from January 1966 through July 2009), EMBASE (from January 1980 to July 2009), and the Cochrane Collaboration's Central Register of Controlled Clinical Trials using the following terms as medical subject headings and keywords: fabaceae not soybeans not isoflavones and diet or dietary fiber and cholesterol or hypercholesterolemia or triglycerides or cardiovascular diseases. Bibliographies of all retrieved articles were also searched. From 140 relevant reports, 10 randomized clinical trials were selected which compared a non-soy legume diet to control, had a minimum duration of 3 weeks, and reported blood lipid changes during intervention and control. Data on sample size, participant characteristics, study design, intervention methods, duration, and treatment results were independently abstracted by 2 investigators using a standardized protocol. Data from 10 trials representing 268 participants were examined using a random-effects model. Pooled mean net change in total cholesterol for those treated with a legume diet compared to control was -11.8 mg/dL (95% confidence interval [CI], -16.1 to -7.5); mean net change in low-density lipoprotein cholesterol was -8.0mg/dL (95% CI, -11.4 to -4.6).

CONCLUSION

These results indicate that a diet rich in legumes other than soy decreases total and LDL cholesterol.

Abstract P3-12-11: Combining Genotype at Low Penetrance Breast Cancer Loci with Family History Risk Leads to Significant Risk Reclassification

Background: A significant proportion of women are at increased genetic risk of breast cancer. Mutations in high penetrance genes such as BRCA1 and BRCA2 are only responsible in the minority of cases, with low penetrance polymorphisms in other genes expected to account for the majority of the remaining genetic risk. An increasing number of such low penetrance polymorphisms are being identified, but each polymorphism only contributes a small amount to overall risk. Currently, in clinical practice, women who are at increased risk of breast cancer are identified by their family history, and the role of genetic testing for multifactorial risk remains uncertain. We have taken the population frequency and genotype relative risk information for the 18 most established low penetrance breast cancer risk loci and explored the effect of combining information from these loci, with risk derived from family history. Results: Genotyping at these 18 loci could provide significant risk information for an individual. The top 1% of women in the genotype risk distribution would have a risk of breast cancer of 2.11 times the general population. At this level of risk, they would qualify for breast cancer screening from age 40 according to evidence based guidelines issued by the UK National Institute of Clinical Excellence (NICE). In addition, the top 5% of the population are at 1.67 times risk of breast cancer and would have the same risk at age 40 as a 50 year old at population risk who would qualify for breast screening according to UK and US National Screening Guidelines. To investigate whether low penetrance genotype has greater potential if combined with other risk factors, we used a simple multiplicative model to combine family history risk of cancer derived using BOADICEA with genotype information. Our data suggest that genotype would result in a significant reclassification of individual risk. For example, 10% of women who only had a sister affected with breast cancer at 55 would qualify for additional screening under NICE criteria if genotype were taken into account. Extending this approach with 160 complex family histories from the Tayside family history breast clinic, we have shown that genotyping could result in reclassification and change of management for 19.1% of women being assessed in this clinic, with 12.4% of women moving into a higher risk category, and 6.7% of women moving into a lower category. Discussion: These data suggest that genotyping for low penetrance breast cancer risk loci is clinically relevant, and that it will be more powerful if it can be combined with other established risk factors.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-12-11.

Increased mortality in HER2 positive, oestrogen receptor positive invasive breast cancer: a population-based study

BACKGROUND

This study assessed the impact of human epidermal growth factor receptor 2 (HER2) status on the outcomes in an unselected population of breast cancer patients who did not receive HER2-targeted therapy.

METHODS

HER2 status by immunohistochemistry and fluorescence in situ hybridisation was compared with clinicopathological data, overall survival (OS) and disease-free survival (DFS) for all patients presenting with breast cancer over 3 years.

RESULTS

In 865 patients (median follow up 6.02 years), HER2 positivity was identified in 13.3% of all cancers and was associated with higher tumour grade (P<10(-8)), lymphovascular invasion (P<0.001) and axillary nodal metastasis (P=0.003). There was a negative association with oestrogen-receptor (ER) and progesterone-receptor expression (P<10(-8)), but the majority (57%) of HER2+tumours were ER+HER2 positivity was associated with poorer OS (P=0.0046) and DFS (P=0.0001) confined to the lymph node-positive (LN+) and ER+ subgroups.

CONCLUSION

HER2-positive cancers were less common in this population-based cohort than most selected series. The association of HER2 positivity with poor prognosis was confined to the ER+ and LN+ subgroups. The survival deficit for the 7.5% of patients with ER+/HER2+ cancer compared with ER+/HER2- patients points to a significant subgroup of women who may not (currently) be considered for HER2-directed therapy.

Bargaining babblers: vocal negotiation of cooperative behaviour in a social bird

Wherever individuals perform cooperative behaviours, each should be selected to adjust their own current contributions in relation to the likely future contributions of their collaborators. Here, we use the sentinel system of pied babblers (Turdoides bicolor) to show that individuals anticipate contributions by group mates, adjusting their own contribution in response to information about internal state broadcast by others. Specifically, we show that (i) short-term changes in state influence contributions to a cooperative behaviour, (ii) individuals communicate short-term changes in state, and (iii) individuals use information about the state of group mates to adjust their own investment in sentinel behaviour. Our results demonstrate that individual decisions about contributions to a cooperative effort can be influenced by information about the likely future contribution of others. We suggest that similar pre-emptive adjustments based on information obtained from collaborators will be a common feature of cooperative behaviour, and may play an important role in the development of complex communication in social species.