Integrating Circulating Tumor Cell Assays into the Management of Breast Cancer

Role of Exosomes in Photodynamic Anticancer Therapy

Photodynamic Therapy (PDT) is a promising alternative treatment for malignancies based on photochemical reaction induced by Photosensitizers (PS) under light irradiation. Recent studies show that PDT caused the abundant release of exosomes from tumor tissues. It is well-known that exosomes as carriers play an important role in cell-cell communication through transporting many kinds of bioactive molecules (e.g. lipids, proteins, mRNA, miRNA and lncRNA). Therefore, to explore the role of exosomes in photodynamic anticancer therapy has been attracting significant attention. In the present paper, we will briefly introduce the basic principle of PDT and exosomes, and focus on discussing the role of exosomes in photodynamic anticancer therapy, to further enrich and boost the development of PDT.

Statistical performance of image cytometry for DNA, lipids, cytokeratin, & CD45 in a model system for circulation tumor cell detection

Detection of circulating tumor cells (CTCs) in a blood sample is limited by the sensitivity and specificity of the biomarker panel used to identify CTCs over other blood cells. In this work, we present Bayesian theory that shows how test sensitivity and specificity set the rarity of cell that a test can detect. We perform our calculation of sensitivity and specificity on our image cytometry biomarker panel by testing on pure disease positive (D⁺ ) populations (MCF7 cells) and pure disease negative populations (D^- ) (leukocytes). In this system, we performed multi-channel confocal fluorescence microscopy to image biomarkers of DNA, lipids, CD45, and Cytokeratin. Using custom software, we segmented our confocal images into regions of interest consisting of individual cells and computed the image metrics of total signal, second spatial moment, spatial frequency second moment, and the product of the spatial-spatial frequency moments. We present our analysis of these 16 features. The best performing of the 16 features produced an average separation of three standard deviations between D⁺ and D^- and an average detectable rarity of ∼1 in 200. We performed multivariable regression and feature selection to combine multiple features for increased performance and showed an average separation of seven standard deviations between the D⁺ and D^- populations making our average detectable rarity of ∼1 in 480. Histograms and receiver operating characteristics (ROC) curves for these features and regressions are presented. We conclude that simple regression analysis holds promise to further improve the separation of rare cells in cytometry applications. © 2017 International Society for Advancement of Cytometry.

Phase II trial of bevacizumab and satraplatin in docetaxel-pretreated metastatic castrate-resistant prostate cancer

BACKGROUND

Satraplatin is an oral platinum compound that has demonstrated efficacy and tolerability in prostate cancer. Preclinical synergy between bevacizumab and platinum has been noted.

METHODS

Docetaxel-pretreated metastatic castrate-resistant prostate cancer patients with disease progression were eligible. Satraplatin 80 mg/m(2) orally on days 1 to 5, prednisone 5mg twice daily, and bevacizumab 10mg/kg on day 1, and 15 mg/kg on day 15 were administered in 35-day cycles.

RESULTS

Thirty one patients were enrolled. Grade 3 or 4 toxicities were pulmonary embolism in 2 patients and thrombocytopenia in 1 patient. 31% of the patients had a ≥ 30% decline in prostate-specific antigen. Median time to progression was 7.0 months (90% confidence interval [CI] 4.7-8.5mo) and median overall survival was 11.2 months (90% CI 9.1-16.4 mo). Polymorphism in the excision repair cross-complementation-1 (ERCC-1) gene was associated with time to progression (hazard ratio = 1.91). A circulating tumor cell count ≥ 5 was moderately prognostic of overall survival (hazard ratio = 1.49) as compared with CTC <5.

CONCLUSIONS

The combination was tolerable, and revealed promising efficacy in metastatic castrate-resistant prostate cancer. ERCC1 genotype maybe predictive of clinical benefit with platinum-based therapy in metastatic prostate cancer.

Tomographic sensing and localization of fluorescently labeled circulating cells in mice in vivo

Sensing and enumeration of specific types of circulating cells in small animals is an important problem in many areas of biomedical research. Microscopy-based fluorescence in vivo flow cytometry methods have been developed previously, but these are typically limited to sampling of very small blood volumes, so that very rare circulating cells may escape detection. Recently, we described the development of a 'diffuse fluorescence flow cytometer' (DFFC) that allows sampling of much larger blood vessels and therefore circulating blood volumes in the hindlimb, forelimb or tail of a mouse. In this work, we extend this concept by developing and validating a method to tomographically localize circulating fluorescently labeled cells in the cross section of a tissue simulating optical flow phantom and mouse limb. This was achieved using two modulated light sources and an array of six fiber-coupled detectors that allowed rapid, high-sensitivity acquisition of full tomographic data sets at 10 Hz. These were reconstructed into two-dimensional cross-sectional images using Monte Carlo models of light propagation and the randomized algebraic reconstruction technique. We were able to obtain continuous images of moving cells in the sample cross section with 0.5 mm accuracy or better. We first demonstrated this concept in limb-mimicking optical flow photons with up to four flow channels, and then in the tails of mice with fluorescently labeled multiple myeloma cells. This approach increases the overall diagnostic utility of our DFFC instrument.

Phase II trial of the mTOR inhibitor, temsirolimus and evaluation of circulating tumor cells and tumor biomarkers in persistent and recurrent epithelial ovarian and primary peritoneal malignancies: a Gynecologic Oncology Group study

OBJECTIVE

Patients with persistent/recurrent epithelial ovarian cancer/primary peritoneal cancer (EOC/PPC) have limited treatment options. AKT and PI3K pathway activation is common in EOC/PPC, resulting in constitutive activation of downstream mTOR. The GOG conducted a phase II evaluation of efficacy and safety for the mTOR inhibitor, temsirolimus in EOC/PPC and explored circulating tumor cells (CTC) and AKT/mTOR/downstream tumor markers.

METHODS

Eligible women with measurable, persistent/recurrent EOC/PPC who had received 1-3 prior regimens were treated with 25mg weekly IV temsirolimus until progression or intolerable toxicity. Primary endpoints were progression-free survival (PFS) ≥6-months, tumor response, and toxicity. CellSearch® system was used to examine CTC, and AKT/mTOR/downstream markers were evaluated by archival tumor immunohistochemistry. Kendall's tau-b correlation coefficient (r) and Cox regression modeling were used to explore marker associations with baseline characteristics and outcome.

RESULTS

Sixty patients were enrolled in a two-stage sequential design. Of 54 eligible and evaluable patients, 24.1% (90% CI 14.9%-38.6%) had PFS ≥6 months (median 3.1 months), 9.3% (90% CI 3.7%-23.4%) experienced a partial response. Grade 3/4 adverse events included metabolic (8), gastrointestinal (8), pain (6), constitutional (5) and pulmonary (4). Suggested associations were between cyclin D1 and PFS ≥6 months, PFS or survival; positive CTC pre-treatment and lack of response; and high CTC expression of M30 and PFS ≥6 months/longer PFS.

CONCLUSIONS

Temsirolimus appears to have modest activity in persistent/recurrent EOC/PPC; however, PFS is just below that required to warrant inclusion in phase III studies in unselected patients. Cyclin D1 as a selection marker and CTC measures merit further study.

Genetic factors in metastatic progression of cutaneous melanoma: the future role of circulating melanoma cells in prognosis and management

The greatest potential for improvement of outcome for patients with Cutaneous Malignant Melanoma lies in the prevention of systemic metastasis. Despite extensive investigation, current prognostic indicators either alone or in combination, although related to melanoma progression, are not sufficient to accurately predict the pattern of progression and outcome for any individual patient. Metastasis related death has been recorded in patients initially diagnosed with early stage tumour as well as in patients many years after initial tumour removal. The trouble finding a predictable pattern in the puzzle of melanoma progression may be linked to the fact that most of the material studied for prognosis is either, cutaneous primaries or metastatic deposits, rather than the melanoma cells in the circulatory system which are responsible for disease progression. In this review article we discuss the potential use of circulating tumour cell (CTC) detection and quantification for identifying patients at risk of metastatic deposits. We also discuss current therapies for the treatment of metastatic melanoma and analyse how CTCs may be used to evaluate the effectiveness of current therapies and to pinpoint patients who require further treatment.

M30 neoepitope expression in epithelial cancer: quantification of apoptosis in circulating tumor cells by CellSearch analysis

PURPOSE

This study aimed to detect the M30 neoepitope on circulating tumor cells (CTC) as a tool for quantifying apoptotic CTC throughout disease course and treatment.

EXPERIMENTAL DESIGN

An automated sample preparation and analysis platform for computing CTC (CellSearch) was integrated with a monoclonal antibody (M30) targeting a neoepitope disclosed by caspase cleavage at cytokeratin 18 (CK18) in early apoptosis. The assay was validated using cell lines and blood samples from healthy volunteers and patients with epithelial cancer.

RESULTS

M30-positive CTC could be detected in >70% of CTC-positive carcinoma patients, which were free for both chemotherapy and radiologic treatments. The fraction of M30-positive CTC varied from 50% to 80%, depending on the histotype. To investigate the potential application of the M30 CTC assay for the evaluation of response in early phase trials, CTC and M30-positive CTC were enumerated in a small case series of breast cancer patients during treatment. Results indicate that changes in the balance of M30-negative/positive CTC may be used as a dynamic parameter indicating an active disease, as documented by consistent radiologic findings.

CONCLUSIONS

M30 expression on CTC is detectable by immunofluorescence. The M30-integrated test has potential for monitoring dynamic changes in the quote of apoptotic CTC (in addition to CTC count) to evaluate response in clinical trials of molecularly targeted anticancer therapeutics as well as for translational research, in which there is a pressing need for informative circulating biomarkers.

Circulating tumor cell analysis: technical and statistical considerations for application to the clinic

Solid cancers are a leading cause of death worldwide, primarily due to the failure of effective clinical detection and treatment of metastatic disease in distant sites. There is growing evidence that the presence of circulating tumor cells (CTCs) in the blood of cancer patients may be an important indicator of the potential for metastatic disease and poor prognosis. Technological advances have now facilitated the enumeration and characterization of CTCs using methods such as PCR, flow cytometry, image-based immunologic approaches, immunomagnetic techniques, and microchip technology. However, the rare nature of these cells requires that very sensitive and robust detection/enumeration methods be developed and validated in order to implement CTC analysis for widespread use in the clinic. This review will focus on the important technical and statistical considerations that must be taken into account when designing and implementing CTC assays, as well as the subsequent interpretation of these results for the purposes of clinical decision making.

Characterization of tumor cell dissemination patterns in preclinical models of cancer metastasis using flow cytometry and laser scanning cytometry

The inability to sensitively detect metastatic cells in preclinical models of cancer has created challenges for studying metastasis in experimental systems. We previously developed a flow cytometry (FCM) method for quantifying circulating tumor cells (CTCs) in mouse models of breast cancer. We have adapted this methodology for analysis of tumor dissemination to bone marrow (BM) and lymph node (LN), and for analysis of these samples by laser scanning cytometry (LSC). Our objective was to implement these methodologies for characterization of tumor cell dissemination in preclinical models of cancer metastasis. Human cancer cells were injected into mice via mammary fat pad (MFP; spontaneous metastasis), tail vein (TV; targets lung), or intracardiac (IC; targets bone) routes. At several time points postinjection (4 h to 8 weeks), mice were sacrificed and blood, LNs, and BM were collected. Samples were immunomagnetically enriched and labeled with human leukocytic antigen-fluorescein isothiocyanate and CD45-PE antibodies (FCM/LSC), and propidium iodide (FCM) prior to quantitative analysis. Following MFP injection, CTCs increased over time, as did disseminated cells to the LN. Interestingly, tumor cells also spontaneously disseminated to BM, peaking at 2 weeks postinjection. Following TV injection, CTCs were initially high but decreased rapidly by 1 week before increasing to peak at endpoint. Combined with an observed concurrent increase in disseminated cells to LN and BM, this suggests that tumor cells may shed into the circulation from lung metastases that establish following initial cell delivery. Following IC injection, CTCs increased over time, peaking at 4 weeks. Tumor cells in the BM (most prevalent site of metastasis after IC injection) remained at moderate levels until peaking at endpoint. Combined use of FCM and LSC allows sensitive quantification of disseminated tumor cells in preclinical models of metastasis. These methods will be valuable for future studies aimed at testing new therapeutics in the metastatic setting.

Flow cytometric assessment of monocyte activation markers and circulating endothelial cells in patients with localized or metastatic breast cancer

BACKGROUND

Monocyte activation in cancer patients may be reflective of anticancer activity. However, studies indicate that recruitment of macrophages can actually promote tumor growth and angiogenesis. Assessment of other microenvironmental cells such as circulating endothelial cells (CECs) may provide additional information regarding disease progression. The objective of this study was to assess monocyte activation and CECs in breast cancer patients and determine the potential clinical relevance during disease progression.

METHODS

Patients (n = 41) with localized or metastatic breast cancer who were not currently receiving treatment were eligible for study inclusion. Peripheral blood was collected and analyzed by flow cytometry for monocyte activation (Leuko64 assay kit), and for CECs (CD146(+)CD45(-) phenotype).

RESULTS

Metastatic breast cancer patients demonstrated a higher monocyte CD64 index relative to normal donors and localized breast cancer patients (P < 0.05). Furthermore, breast cancer patients had a lower monocyte CD163 index relative to normal donors (P = 0.008). Localized breast cancer patients demonstrated higher levels of CD146(+)CD45(-) cells CECs relative to metastatic breast cancer patients and normal donors. Within the localized breast cancer population, levels of CD146(+)CD45(-) cells increased with disease stage (P < 0.05).

CONCLUSIONS

These results suggest that monocyte activation and CECs may play a role in breast cancer progression. We speculate that monocyte activation may reflect a reaction to metastatic cells and/or response to tissue damage caused by metastatic growth in distant organs. Furthermore, the observation that CECs increase with disease stage in localized breast cancer suggests that CECs could be a useful surrogate marker for disease progression in this patient population.