Stephanie Lim

New frontiers in circulating tumor cell analysis: A reference guide for biomolecular profiling toward translational clinical use

Circulating tumor cells (CTCs) are now routinely isolated from blood, and measurement of CTC concentrations appears to correlate well with survival in patients with cancer. Interrogation of the molecular profile of CTCs for expression of protein biomarkers, genetic variants and gene expression provides opportunities to use this information to guide personalized treatment, monitor therapy and detect emerging resistance. However, successful application of profiling techniques requires analyses that deliver a reliable and clinically relevant representation of a patients cancer as it changes with time. Here, we comprehensively review the current knowledge of therapeutically relevant biomarkers in isolated CTCs obtained by fluorescence imaging and genomic profiling approaches. The reviewed data support the notion that molecular profiling of CTCs will provide a reliable representation or surrogate index of tumor burden. Large‐scale translational trials, many currently in progress, will provide critical data to progress CTC analysis toward wider clinical use in personalized treatment.

Predictive and prognostic biomarkers for neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Locally advanced rectal cancer is regularly treated with trimodality therapy consisting of neoadjuvant chemoradiation, surgery and adjuvant chemotherapy. There is a need for biomarkers to assess treatment response, and aid in stratification of patient risk to adapt and personalise components of the therapy. Currently, pathological stage and tumour regression grade are used to assess response. Experimental markers include proteins involved in cell proliferation, apoptosis, angiogenesis, the epithelial to mesenchymal transition and microsatellite instability. As yet, no single marker is sufficiently robust to have clinical utility. Microarrays that screen a tumour for multiple promising candidate markers, gene expression and microRNA profiling will likely have higher yield and it is expected that a combination or panel of markers would prove most useful. Moving forward, utilising serial samples of circulating tumour cells or circulating nucleic acids can potentially allow us to demonstrate tumour heterogeneity, document mutational changes and subsequently measure treatment response.

Circulating tumour cells and the epithelial mesenchymal transition in colorectal cancer

Circulating tumour cells (CTCs) hold great potential as liquid biopsies to prognosticate disease and guide treatment in colorectal cancer. However, their emerging role in determining the molecular phenotype of tumour metastasis carries even more promising clinical use in the provision of comprehensive biomarker detection for targeted therapies and determination of drug resistance. The isolation of CTCs is technology dependent, and in the case of epithelial cell adhesion molecule-based platforms, the ability to detect cells that have undergone the epithelial to mesenchymal transition (EMT) is ineffective. CTCs displaying a mesenchymal phenotype are believed to have an increased metastatic potential. The rarity of CTCs provides another challenge in the enumeration of these cells. The future will likely involve the analysis of individual CTCs at any stage of the EMT in order to provide real-time phenotypic and molecular snapshots capable of tracking the dynamic evolution of tumour progression over time.

Upregulated Polo-Like Kinase 1 Expression Correlates with Inferior Survival Outcomes in Rectal Cancer.

Background Human polo-like kinase 1 (PLK1) expression has been associated with inferior outcomes in colorectal cancer. Our aims were to analyse PLK1 in rectal cancer, and its association with clinicopathological variables, overall survival as well as tumour regression to neoadjuvant treatment. Methods PLK1 expression was quantified with immunohistochemistry in the centre and periphery (invasive front) of rectal cancers, as well as in the involved regional lymph nodes from 286 patients. Scores were based on staining intensity and percentage of positive cells, multiplied to give weighted scores from 1–12, dichotomised into low (0–5) or high (6–12). Results PLK1 scores in the tumour periphery were significantly different to adjacent normal mucosa. Survival analysis revealed that low PLK1 score in the tumour periphery had a hazard ratio of death of 0.59 in multivariate analysis. Other predictors of survival included age, tumour depth, metastatic status, vascular and perineural invasion and adjuvant chemotherapy. There was no statistically significant correlation between PLK1 score and histological tumour regression in the neoadjuvant cohort. Conclusion Low PLK1 score was an independent predictor of superior overall survival, adjusting for multiple clinicopathological variables including treatment.

Oxidative stress in prostate cancer patients: A systematic review of case control studies

Background Prostate cancer (PCa) is the most common cancer in men in Western countries. In-vitro and in-vivo studies suggest that oxidative stress (OS) and antioxidants play a key role in the pathogenesis of chronic diseases including PCa, which is promoted by the production of reactive oxygen species and impaired antioxidant defense mechanisms. This study evaluates the association between OS and men with PCa. Methods A literature search was carried out on Medline, PubMed, and ScienceDirect databases, as well as manual searches from inception up to August 2015 using the keywords “Oxidative stress” or “Reactive oxygen species” or “Lipid peroxidation” AND “Prostate cancer.” All studies including data on the measurement of OS biomarkers in PCa were included. Results Twenty-three case control studies were retrieved with sample sizes ranging from 15 to 3,613 (6,439 participants in total). Markers of OS were significantly higher in patients with PCa compared with control groups in 21 studies. Two self-controlled case studies comparing OS between PCa cells and non-PCa cells in tissue biopsies found OS to be statistically higher in PCa cancer cells. Results on markers of antioxidant capacity (superoxide dismutase, catalase, glutathione, glutathione reductase, glutathione peroxidase, uric acid, lutein, lycopene, beta carotein, vitamin A, vitamin C, vitamin E, and total antioxidants) were not completely consistent in their association with PCa. Conclusions Upregulated OS profiles and impairment of antioxidant defense systems may play a role in men with PCa. To confirm these findings, robust clinical trials utilizing a personalized approach which monitors both OS and antioxidant markers during therapy are warranted.

Circulating tumour cells and circulating nucleic acids as a measure of tumour dissemination in non-metastatic colorectal cancer surgery.

There is accumulating evidence for circulating tumour cells (CTCs) and circulating tumour nucleic acids (ctNAs) as prognostic and predictive biomarkers in colorectal cancer. Their role in the perioperative setting is evolving. These blood-borne biomarkers can potentially demonstrate tumour dissemination at time of colorectal cancer surgery and estimate the completeness of a surgical resection. CTCs and circulating ctNA levels at time of surgery, and persistent levels post-surgery, may correlate with poorer patient outcomes. These biomarkers can be utilised to refine surgical techniques to minimise tumour dissemination and determine the need for adjuvant therapy.

Systemic therapy in neurofibromatosis type 2.

The systemic treatment of patients with neurofibromatosis type 2 associated tumours is challenging, as these patients often have prolonged survival but with the inevitable propensity for their disease to cause symptoms, and no effective therapies other than local treatments such as surgery. Understanding the molecular mechanisms driving NF-2 pathogenesis holds promise for the potential use of targeted therapy. Initial studies of agents such as bevacizumab (angiogenesis inhibitor) and lapatinib (epidermal growth factor and ErbB2 inhibitor) have indicated benefit for selected patients. As the biology of NF-2 is dependent on multiple interlinked downstream signalling pathways, targeting multiple pathways may be more effective than single agents. Phase zero trials, adaptive phase II or small multi-arm trials, are likely the way forward in this rare disease. Ideally, well-tolerated targeted therapy would appear to be the most promising approach for patients with NF-2, given the natural history of this disease.

Traditional Oriental Herbal Medicine and Natural Killer Cells for Cancer Patients: A Systematic Review and Meta-analysis.

Traditional oriental herbal medicine (HM) is used by cancer patients to improve immunity. Natural killer (NK) cells are associated with development and progression of tumor and survival of cancer patients. This literature review examined randomized controlled trials (RCTs) in four electronic databases until October 2015 to evaluate the effects of oral HM on NK cells in cancer patients. Data were pooled and computed in a meta‐analysis. The methodological quality was assessed according to the Cochrane risk of bias tool. Sixteen RCTs involving 1326 cancer patients were identified. Combination of HM and conventional treatment was associated with significantly higher level of NK cells compared with conventional cancer treatments (standardized mean difference, 1.218; 95% confidence interval 0.719–1.717; p < 0.001). Eight RCTs reported statistically significant improvements in the proportions or activity of NK cells in patient groups who received both HM and conventional treatment compared with patients who received conventional treatment alone, while eight RCTs reported no statistically significant differences between the two groups. Studies (n = 16) included in this review had insufficient quality of evidence with unclear (n = 1) and high (n = 15) values of the risk of bias. Although traditional oriental HM may have the positive effects on preserving the level of NK cells in cancer patients receiving conventional treatments, current evidence is inconclusive because of lack of high‐quality evidence. Copyright

MRE11 and ATM Expression Levels Predict Rectal Cancer Survival and Their Association with Radiotherapy Response.

Background Aberrant expression of DNA repair proteins is associated with poor survival in cancer patients. We investigated the combined expression of MRE11 and ATM as a predictive marker of response to radiotherapy in rectal cancer. Methods MRE11 and ATM expression were examined in tumor samples from 262 rectal cancer patients who underwent surgery for rectal cancer, including a sub-cohort of 54 patients who were treated with neoadjuvant radiotherapy. The relationship between expression of the two-protein panel and tumor regression grade (TRG) was assessed by Mann–Whitney U test and receiver operating characteristics area under curve (ROC-AUC) analysis. The association between expression of the two-protein panel and clinicopathologic variables and survival was examined by Kaplan-Meier methods and Cox regression analysis. Results A high score for two-protein combined expression in the tumor center (TC) was significantly associated with worse disease-free survival (DFS) (P = 0.035) and overall survival (OS) (P = 0.003) in the whole cohort, and with DFS (P = 0.028) and OS (P = 0.024) in the neoadjuvant subgroup (n = 54). In multivariate analysis, the two-protein combination panel (HR = 2.178, 95% CI 1.115–4.256, P = 0.023) and perineural invasion (HR = 2.183, 95% CI 1.222–3.899, P = 0.008) were significantly associated with DFS. Using ROC-AUC analysis of good versus poor histological tumor response among patients treated preoperatively with radiotherapy, the average ROC-AUC was 0.745 for the combined panel, 0.618 for ATM alone, and 0.711 for MRE11 alone. Conclusions The MRE11/ATM two-protein panel developed in this study may have clinical value as a predictive marker of tumor response to neoadjuvant radiotherapy, and a prognostic marker for disease-free and overall survival.

Imatinib in neurofibromatosis type 2.

Summary A 30-year-old man with a 10-year history of neurofibromatosis type 2 (NF-2) and minimal hearing in his left ear, presented with rapidly progressive disease and risk of total hearing loss. He was started on imatinib and achieved stable disease for 4 months, after which the drug was ceased due to toxicity. He was then treated with bevacizumab for 8 months with a best response of stable disease.