High-resolution imaging for the detection and characterisation of circulating tumour cells from patients with oesophageal, hepatocellular, thyroid and ovarian cancers

Interest has increased in the potential role of circulating tumour cells in cancer management. Most cell‐based studies have been designed to determine the number of circulating tumour cells in a given volume of blood. Ability to understand the biology of the cancer cells would increase the clinical potential. The purpose of this study was to develop and validate a novel, widely applicable method for detection and characterisation of circulating tumour cells. Cells were imaged with an ImageStream^X imaging flow cytometer which allows detection of expression of multiple biomarkers on each cell and produces high‐resolution images. Depletion of haematopoietic cells was by red cell lysis, leukocyte common antigen CD45 depletion and differential centrifugation. Expression of epithelial cell adhesion molecule, cytokeratins, tumour‐type‐specific biomarkers and CD45 was detected by immunofluorescence. Nuclei were identified with DAPI or DRAQ5 and brightfield images of cells were collected. The method is notable for the dearth of cell damage, recoveries greater than 50%, speed and absence of reliance on the expression of a single biomarker by the tumour cells. The high‐quality images obtained ensure confidence in the specificity of the method. Validation of the methodology on samples from patients with oesophageal, hepatocellular, thyroid and ovarian cancers confirms its utility and specificity. Importantly, this adaptable method is applicable to all tumour types including those of nonepithelial origin. The ability to measure simultaneously the expression of multiple biomarkers will facilitate analysis of the cancer cell biology of individual circulating tumour cells.

What's new?

Circulating tumour cells (CTCs) are disseminated malignant cells from which biological and therapeutic information may be obtained non‐invasively. Detection of small CTC populations within the large number of normal blood cells is a challenge. This study describes a novel method for the detection and high‐resolution imaging of CTCs. Unlike most other studies, CTC detection is not reliant upon expression of a single biomarker. The method is applicable to all cancers; the authors present preliminary results from four tumour types. The high quality of the images allows biological characterisation of the tumour cells and increases the clinical potential of the approach.

Antiretroviral procurement and supply chain management

Procurement, the country-level process of ordering antiretrovirals (ARVs), and supply chain management, the mechanism by which they are delivered to health-care facilities, are critical processes required to move ARVs from manufacturers to patients. To provide a glimpse into the ARV procurement and supply chain, the following pages provide an overview of the primary stakeholders, principal operating models, and policies and regulations involved in ARV procurement. Also presented are key challenges that need to be addressed to ensure that the supply chain is not a barrier to the goal of universal coverage. This article will cover the steps necessary to order and distribute ARVs, including different models of delivery, key stakeholders involved, strategic considerations that vary depending on context and policies affecting them. The single drug examples given illustrate the complications inherent in fragmented supply and demand-driven models of procurement and supply chain management, and suggest tools for navigating these hurdles that will ultimately result in more secure and reliable ARV provision. Understanding the dynamics of ARV supply chain is important for the global health community, both to ensure full and efficient treatment of persons living with HIV as well as to inform the supply chain decisions for other public health products.

Identification of dual DNA-PK MDR1 inhibitors for the potentiation of cytotoxic drug activity

Inhibition of DNA repair is an attractive therapeutic approach to enhance the activity of DNA-damaging anticancer chemotherapeutic agents. Similarly, blockade of the multidrug-resistance protein 1 (MDR1) can overcome efflux-mediated resistance. DNA-dependent protein kinase (DNA-PK) is essential for the non-homologous end-joining DNA repair pathway. NU7441 is a potent DNA-PK inhibitor (IC50=14nM) that is used widely to study the effects of DNA-PK inhibition in vitro. In growth inhibition studies, 1μM NU7441 sensitised vincristine-resistant CCRF-CEM VCR/R leukaemia cells (1200-fold resistant) to a range of MDR1 substrates, including doxorubicin (8-fold, p=0.03), vincristine (14-fold, p=0.01) and etoposide (63-fold, p=0.02), compared with 1.4-fold (p=0.02), 2.2-fold (p=0.04) and 3.6-fold (p=0.01) sensitisation, respectively, in parental CCRF-CEM cells. This difference in NU7441 sensitivity was confirmed in another two parental and MDR1-overexpressing cell line pairs. A doxorubicin fluorescence assay showed that in MDR1-overexpressing canine kidney MDCKII-MDR1 cells, 1μM NU7441 increased doxorubicin nuclear fluorescence 16-fold. NU7441 and 3 structurally related compounds (NU7742 (an NU7441 analogue that does not inhibit DNA-PK - IC50>10μM), DRN1 (DNA-PK-inhibitory atropisomeric NU7441 derivative - IC50=2nM) and DRN2 (DNA-PK non-inhibitory atropisomeric NU7441 derivative - IC50=7μM)) all increased intracellular vincristine accumulation in the CCRF-CEM VCR/R cells to a level similar to verapamil, as measured by LC-MS. This paper demonstrates that NU7441 is a dual DNA-PK and MDR1 inhibitor, and this extends the therapeutic potential of the compound when used in combination with MDR substrates.

Abstract 3329: The DNA-PK inhibitor, NU7441, sensitises cancer cells to microtubule-targeting agents and modulates vincristine efflux in multidrug resistant cells

Microtubules are involved in the formation of the mitotic spindle, and correct separation of the sister chromatids at mitosis is essential for maintaining genomic stability. Microtubule-targeting drugs arrest rapidly-dividing cells and are important chemotherapeutic agents, but the development of multidrug-resistance (MDR) is a serious clinical problem. Along with its role in DNA double-strand break repair, DNA-dependent protein kinase (DNA-PK) has also been shown to play an important role in stabilising spindle formation and preventing mitotic catastrophe (Shang et al, Cancer Res. 2010). In light of this novel finding, we hypothesised that inhibition of DNA-PK would sensitise cells to microtubule-targeting agents. Pilot studies showed that inhibition of DNA-PK by the selective inhibitor, NU7441, caused greater sensitisation to vincristine in multidrug-resistant cells compared to parental cells. Here, we further investigate the role of DNA-PK in response to microtubule-targeting drugs using a novel series of NU7441 analogues, and investigate whether these inhibitors interact with the efflux transporter, P-glycoprotein.

In growth inhibition studies, CCRF-CEM leukaemia cells were sensitised 1.4-fold to vincristine by NU7441 (1μM) whereas their vincristine-resistant derivative CCRF-CEM VCR/R cells were sensitised 8-fold to vincristine. DNA-PK-deficient M059J glioblastoma cells were 2-fold more sensitive to docetaxel than DNA-PK-proficient cells, and NU7441 sensitised only DNA-PK-proficient M059J-Fus1 cells to docetaxel. CCRF-CEM VCR/R cells have a higher basal level of autophosphorylation of DNA-PKcs (Western blotting) than the CCRF-CEM cells and autophosphorylation in response to vincristine was abrogated by NU7441.

To investigate the effects of NU7441 on drug transport, a doxorubicin fluorescence assay showed that in P-glycoprotein-overexpressing canine kidney MDCKII-MDR1 cells, 1μM NU7441 increased doxorubicin cellular fluorescence 16-fold by blocking drug efflux via P-glycoprotein. NU7441 and 3 structurally-related compounds (NU7742 (inactive NU7441 analogue), DRN1 (DNA-PK-inhibitory atropisomeric NU7441 derivative) or DRN2 (DNA-PK non-inhibitory atropisomeric NU7441 derivative)) all increased intracellular vincristine accumulation in the CCRF-CEM VCR/R cells to a level similar to verapamil, as measured by LC-MS. However, the non-inhibitory compound NU7742 was 5-fold less effective at sensitising CCRF-CEM VCR/R cells to vincristine than NU7441 (p=0.008).

The novel finding that DNA-PK inhibition sensitises cells to microtubule-targeting agents suggests that along with its function in DNA repair, this enzyme plays a role in the mitotic spindle checkpoint. Additionally, in multidrug-resistant cells, NU7441 is able to block drug efflux via interaction with P-glycoprotein.

Citation Format: Emily Mould, Philip Berry, David Jamieson, Christopher Hill, Niu Tan, Sarah Elliott, Barbara Durkacz, David Newell, Elaine Willmore. The DNA-PK inhibitor, NU7441, sensitises cancer cells to microtubule-targeting agents and modulates vincristine efflux in multidrug resistant cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3329. doi:10.1158/1538-7445.AM2013-3329

Characterisation of the roles of ABCB1, ABCC1, ABCC2 and ABCG2 in the transport and pharmacokinetics of actinomycin D in vitro and in vivo

Actinomycin D plays a key role in the successful treatment of Wilms tumour. However, associated liver toxicities remain a drawback to potentially curative treatment. We have used MDCKII cells over-expressing ABCB1, ABCC1, ABCC2 and ABCG2, alongside knockout mouse models to characterise actinomycin D transport and its impact on pharmacokinetics. Growth inhibition, intracellular accumulation and cellular efflux assays were utilised. A 59-fold difference in GI₅₀ was observed between MDCKII-WT and MDCKII-ABCB1 cells (12.7 nM vs. 745 nM, p < 0.0001). Reduced sensitivity was also seen in MDCKII-ABCC1 and ABCC2 cells (GI₅₀ 25.7 and 40.4 nM respectively, p < 0.0001). Lower intracellular accumulation of actinomycin D was observed in MDCKII-ABCB1 cells as compared to MDCKII-WT (0.98 nM vs. 0.1 nM, p < 0.0001), which was reversed upon ABCB1 inhibition. Lower accumulation was also seen in MDCKII-ABCC1 and ABCC2 cells. Actinomycin D efflux over 2 h was most pronounced in MDCKII-ABCB1 cells, with 5.5-fold lower intracellular levels compared to WT. In vivo studies showed that actinomycin D plasma concentrations were significantly higher in Abcb1a/1b^−/− as compared to WT mice following administration of 0.5 mg/kg actinomycin D (AUC_0–6 h 242 vs. 152 μg/L h respectively). While comparable actinomycin D concentrations were observed in the kidneys and livers of Abcb1a/1b^−/− and Abcc2^−/− mice, concentrations in the brain were significantly higher at 6 h following drug administration in Abcb1a/1b^−/− mice compared to WT. Results confirm actinomycin D as a substrate for ABCB1, ABCC1 and ABCC2, and indicate that Abcb1a/1b and Abcc2 can influence the in vivo disposition of actinomycin D. These data have implications for ongoing clinical pharmacology trials involving children treated with actinomycin D.

Institutional Profile: Pharmacogenomics research at Newcastle University

Newcastle University has been active in the field of pharmacogenomics/pharmacogenetics research since 1988. Research activity is based at the Faculty of Medical Sciences and is led by four professors within two separate research institutes. This article describes the various ongoing research projects and the teams involved together with our teaching activities in the subject.

The impact of retinoic acid treatment on the sensitivity of neuroblastoma cells to fenretinide

Despite the successful introduction of 13-cis retinoic acid (13cisRA) therapy for the treatment of neuroblastoma, approximately 50% patients do not respond or experience relapse. A retinoid analogue, fenretinide [N-(4-hydroxyphenyl) retinamide; 4-HPR] can induce apoptosis in neuroblastoma cell lines and could have clinical use after therapy with 13cisRA. However, there are important questions concerning potential retinoid drug interactions which need to be addressed. The aim of this study was to investigate the influence of retinoic acid pre-treatment on fenretinide-induced apoptosis and fenretinide metabolism in neuroblastoma cell lines. Apoptosis was measured by flow cytometry of propidium iodide-stained neuroblastoma cells and a live-cell imaging assay. Intracellular fenretinide metabolism was determined by HPLC analysis. Pre-treatment of neuroblastoma cell lines with retinoic acid (RA) resulted in a significant decrease in the apoptotic response to fenretinide in three of the four lines tested. Comparison between responsive and non-responsive cell lines suggested that RA sensitivity was required to promote fenretinide resistance, and that this was mediated by up-regulation of Bcl-2 and the inhibition of pro-apoptotic fenretinide signalling pathways. Induction of the oxidative metabolism of fenretinide after RA pre-treatment did not significantly impact on intracellular parent drug levels and is unlikely to explain the decreased apoptotic response observed. The interaction between RA and fenretinide could have important implications for the scheduling of fenretinide in therapeutic protocols for neuroblastoma.

Keratinocyte apoptosis in epidermal remodeling and clearance of psoriasis induced by UV radiation

Psoriasis is a common chronic skin disorder, but the mechanisms involved in the resolution and clearance of plaques remain poorly defined. We investigated the mechanism of action of UVB, which is highly effective in clearing psoriasis and inducing remission, and tested the hypothesis that apoptosis is a key mechanism. To distinguish bystander effects, equal erythemal doses of two UVB wavelengths were compared following in vivo irradiation of psoriatic plaques; one is clinically effective (311 nm) and one has no therapeutic effect on psoriasis (290 nm). Only 311 nm UVB induced significant apoptosis in lesional epidermis, and most apoptotic cells were keratinocytes. To determine clinical relevance, we created a computational model of psoriatic epidermis. Modeling predicted apoptosis would occur in both stem and transit-amplifying cells to account for plaque clearance; this was confirmed and quantified experimentally. The median rate of keratinocyte apoptosis from onset to cell death was 20 minutes. These data were fed back into the model and demonstrated that the observed level of keratinocyte apoptosis was sufficient to explain UVB-induced plaque resolution. Our human studies combined with a systems biology approach demonstrate that keratinocyte apoptosis is a key mechanism in psoriatic plaques clearance, providing the basis for future molecular investigation and therapeutic development.

Use of generic antiretroviral agents and cost savings in PEPFAR treatment programs

CONTEXT

One of the biggest hurdles to the rapid scale-up of antiretroviral therapy in the developing world was the price of antiretroviral drugs (ARVs). Modification of an existing US Food and Drug Administration (FDA) process to expedite review and approval of generic ARVs quickly resulted in a large number of FDA-tentatively approved ARVs available for use by the US President's Emergency Plan for AIDS Relief (PEPFAR).

OBJECTIVE

To evaluate the uptake of generic ARVs among PEPFAR-supported programs in Guyana, Haiti, Vietnam, and 13 countries in Africa, and changes over time in ARV use and costs.

DESIGN, SETTING, AND PARTICIPANTS

An annual survey from 2005 to 2008 of ARVs purchased in 16 countries by PEPFAR implementing and procurement partners (organizations using PEPFAR funding to purchase ARVs).

MAIN OUTCOME MEASURES

Drug expenditures, ARV types and volumes (assessed per pack, a 1-month supply), proportion of generic procurement across years and countries, and cost savings from generic procurement.

RESULTS

ARV expenditures increased from $116.8 million (2005) to $202.2 million (2008); and procurement increased from 6.2 million to 22.1 million monthly packs. The proportion spent on generic ARVs increased from 9.17% (95% confidence interval [CI], 9.17%-9.18%) in 2005 to 76.41% (95% CI, 76.41%-76.42%) in 2008 (P < .001), and the proportion of generic packs procured increased from 14.8% (95% CI, 14.79%-14.84%) in 2005 to 89.33% (95% CI, 89.32%-89.34%) in 2008 (P < .001). In 2008, there were 8 PEPFAR programs that procured at least 90.0% of ARV packs in generic form; South Africa had the lowest generic procurement (24.7%; 95% CI, 24.6%-24.8%). Procurement of generic fixed-dose combinations increased from 33.3% (95% CI, 33.24%-33.43%) in 2005 to 42.73% (95% CI, 42.71%-42.75%) in 2008. Estimated yearly savings generated through generic ARV use were $8,108,444 in 2005, $24,940,014 in 2006, $75,645,816 in 2007, and $214,648,982 in 2008, a total estimated savings of $323,343,256.

CONCLUSION

Among PEPFAR-supported programs in 16 countries, availability of generic ARVs was associated with increased ARV procurement and substantial estimated cost savings.

Abstract 1674: The NQO1 C609T polymorphism is associated with poorer response to AC adjuvant therapy in the treatment of breast cancer

A non-synonymous SNP in the NAD(P)H: Quinone Oxidoreductase 1 gene has previously been implicated in the response of breast cancer patients to anthracycline containing regimens in a retrospective cohort study. NQO2 is 54% homologous to NQO1 at the primary protein structure and, despite the lack of a characterised endogenous electron donating cofactor for NQO2, the two enzymes share numerous substrates. NQO2, in contrast to NQO1, is additionally capable of reducing reactive quinone metabolites of estradiol. The NQO2 gene has a non-synonymous SNP that has previously been shown to result in a lower average NQO2 activity in cohorts of bladder and ovarian cancer patients. It is unknown if the NQO2 SNP impacts on survival in breast cancer.

Genomic DNA samples from 239 women with early breast cancer were genotyped for the NQO1 (rs1800566) and NQO2 (rs1143684) SNPs. All of the participants were recruited from Medical Oncology out-patient clinics within the Newcastle upon Tyne Hospitals NHS Foundation Trust and were treated with an AC adjuvant therapy regimen with curative intent. Median follow up was 78 months and followed a standard protocol. Genotyping was done by the Taqman RT-PCR method.

The NQO1 SNP was associated with a decreased time to progression (HR 2.8, 95%CI 1.4-5.64, p=0.003), decreased overall survival (HR 3.6, 95%CI 1.4-10, p=0.007) and a lower likelihood of having a dose delay, all indicative of NQO1 mediated sensitisation to the effects of doxorubicin. The NQO2 SNP had no impact on the cohort as a whole but was associated with a decreased overall survival (p=0.009, log-rank) and time to progression (p=0.004, log rank) in patients who were oestrogen receptor (ER) negative.

This study confirms the previous observation of NQO1 genotype influencing response to anthracyclines and indicates a potential impact of an NQO2 SNP on the prognosis of ER negative breast cancer. The mechanism by which NQO2 genotype influences breast survival remains to be elucidated.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1674.

Influence of pharmacogenetics on response and toxicity in breast cancer patients treated with doxorubicin and cyclophosphamide

Background:

Doxorubicin and cyclophosphamide (AC) therapy is an effective treatment for early-stage breast cancer. Doxorubicin is a substrate for ABCB1 and SLC22A16 transporters. Cyclophosphamide is a prodrug that requires oxidation to 4-hydroxycyclophosphamide, which yields a cytotoxic alkylating agent. The initial oxidation is catalysed by cytochrome P450 enzymes including CYP2B6, CYP2C9, CYP2C19 and CYP3A5. Polymorphic variants of the genes coding for these enzymes and transporters have been identified, which may influence the systemic pharmacology of the two drugs. It is not known whether this genetic variation has an impact on the efficacy or toxicity of AC therapy.

Methods:

Germ line DNA samples from 230 patients with breast cancer on AC therapy were genotyped for the following SNPs: ABCB1 C1236T, G2677T/A and C3435T, SLC22A16 A146G, T312C, T755C and T1226C, CYP2B6^*2, ^*8, ^*9, ^*3, ^*4 and ^*5, CYP2C9^*2 and ^*3, CYP3A5^*3 and CYP2C19^*2. Clinical data on survival, toxicity, demographics and pathology were collated.

Results:

A lower incidence of dose delay, indicative of less toxicity, was seen in carriers of the SLC22A16 A146G, T312C, T755C variants. In contrast, a higher incidence of dose delay was seen in carriers of the SLC22A16 1226C, CYP2B6^*2 and CYP2B6^*5 alleles. The ABCB1 2677A, CYP2B6^*2, CYP 2B6^*8, CYP 2B6^*9, CYP 2B6^*4 alleles were associated with a worse outcome.

Conclusion:

Variant alleles in the ABCB1, SLC22A16 and CYP2B6 genes are associated with response to AC therapy in the treatment of breast cancer.

Acute effects of kava on measures of cognitive performance, physiological function and mood

Volunteer subjects were assigned to receive a mixture of the intoxicating substance, kava, in a mixture with fruit juice, or juice alone. Subjects then undertook tasks of acute cognitive functioning, including reaction time and tracking tasks, and a measure of body sway. Heart rate, respiration rate, blood pressure were recorded and subjects were asked to rate their degree of intoxication and complete a stress/arousal check list. Subjects receiving kava reported feelings of intoxication which peaked approximately one hour after kava ingestion. Compared to the group receiving juice alone, the group receiving kava also had increased body sway. There were no other statistically significant differences between groups, although the mean cognitive performance of the group receiving kava was generally poorer.