Abstract 2045: Exploring the potential of cellular thermal shift assay (CETSA) to study drug resistance during cancer therapy

The aim of this project is to understand the various mechanisms contributing to drug resistance development in cancer therapy.

The efficacy of therapeutics is dependent on a drug binding to its target. We have developed a method that allows for the first time to directly evaluate drug binding to target proteins in cells and tissue samples the cellular thermal shift assay (CETSA) (Martinez Molina et al. Science, 341:84). CETSA is based on the biophysical principle of ligand-induced thermal stabilization of target proteins. By monitoring the drug occupancy in the target protein, CETSA can be used to study processes of drug transport and metabolism in cancer cells. We have used CETSA to study the acquired drug resistance of, antifolate and fluropyrimidine drugs in pairs of parental and resistant cell lines. CETSA shifts and isothermal dose response fingerprint (ITDRF) were used to study the relative drug target engagement in these cells. Quantitative mass spectrometry was used to monitor differences in protein expression levels across the cell lines.

Based on the CETSA measurements, resistant cells clearly showed a higher drug dose threshold as compared to the parent cell lines, typically requiring 8-50 times higher dose to establish similar target engagement. Several potential mechanism for drug resistant emerged - we, for example, observed up-regulation of thymidylate synthase and down regulation of reduced folate carrier (RFC) protein associated with antifolate transport, in some resistant cell lines.

The data supports that CETSA is a potential valuable tool to dissect various mechanisms those contribute to resistant development in cancer cells.

Citation Format: Lekshmy Kunjamma Usha Sreekumar, Yan Ting Lim, Saranya Veerappan, Par Nordlund. Exploring the potential of cellular thermal shift assay (CETSA) to study drug resistance during cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2045. doi:10.1158/1538-7445.AM2017-2045

Abstract 4386: CETSA as a new strategy to understand efficacy, adverse effects and resistance development of anticancer drugs

A key step of the action of most drugs is their binding (engagement) of the target protein(s). However, limitations in the available methods for directly accessing this critical step have added uncertainties in many stages of drug development.

We have developed a generic method for evaluating drug binding to target proteins in cells and tissues (Martinez Molina et al. Science, 341:84). The technique is based on the physical phenomenon of ligand-induced thermal stabilization of target proteins; the method is therefore called the cellular thermal shift assay (CETSA). The technique allows for the first time to directly measure the biophysical interactions between a drug and protein target in non- engineered cells and tissues. We show that using CETSA a range of critical factors for drug development can be addressed at the target engagement level, including drug transport and activation, off-target effects, drug resistance as well as drug distribution in cells, patient and animal tissues. Using quantitative mass-spectrometry, proteome-wide CETSA has been established which allows for off-target effects as well as downstream biochemistry to be discovered (Savitsk et al. Science, 346, 6205:1255784). Together the data supports that CETSA is likely to become a valuable tool for developing and understanding the action of cancer drugs in the future.

Citation Format: Pär Nordlund, Sara Lööf, Henritte Laursen, Anette Öberg, Johan Lengqvist, Rozbeh Jafari, Lingyun Dai, Ka DIam Go, Nayana Prabhu, Radoslaw Sobota, Andreas Larsson, Anna Jansson, Chris Heng Tan Soon, Lekshmy Sreekumar, Yan Ting Lim, Daniel Martines Molina. CETSA as a new strategy to understand efficacy, adverse effects and resistance development of anticancer drugs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4386.

Extended loop region of Hcp1 is critical for the assembly and function of type VI secretion system in Burkholderia pseudomallei

The Type VI Secretion System cluster 1 (T6SS1) is essential for the pathogenesis of Burkholderia pseudomallei, the causative agent of melioidosis, a disease endemic in the tropics. Inside host cells, B. pseudomallei escapes into the cytosol and through T6SS1, induces multinucleated giant cell (MNGC) formation that is thought to be important for bacterial cell to cell spread. The hemolysin-coregulated protein (Hcp) is both a T6SS substrate, as well as postulated to form part of the T6SS secretion tube. Our structural study reveals that Hcp1 forms hexameric rings similar to the other Hcp homologs but has an extended loop (Asp40-Arg56) that deviates significantly in position compared to other Hcp structures and may act as a key contact point between adjacent hexameric rings. When two residues within the loop were mutated, the mutant proteins were unable to stack as dodecamers, suggesting defective tube assembly. Moreover, infection with a bacterial mutant containing in situ substitution of these hcp1 residues abolishes Hcp1 secretion inside infected cells and MNGC formation. We further show that Hcp has the ability to preferentially bind to the surface of antigen-presenting cells, which may contribute to its immunogenicity in inducing high titers of antibodies seen in melioidosis patients.

Efficacy and safety of micafungin for the prophylaxis of invasive fungal infection during neutropenia in children and adolescents undergoing allogeneic hematopoietic SCT

The objective of this study was to evaluate the efficacy and safety of micafungin for the prevention of invasive fungal infection (IFI) during the neutropenic phase of allogeneic hematopoietic SCT (allo-HSCT) in children and adolescents. This was a prospective, multicenter, open-label, single-arm study. Micafungin was administered i.v. at a dose of 1 mg/kg/day (max 50 mg) from the beginning of conditioning until neutrophil engraftment. Treatment success was defined as the absence of proven, probable, possible or suspected IFI through to 4 weeks after therapy. From April 2010 to December 2011, 155 patients were enrolled from 11 institutions in Korea, and 147 patients were analyzed. Of the 147 patients, 121 (82.3%) completed the protocol without premature interruption. Of the 132 patients in whom micafungin efficacy could be evaluated, treatment success was achieved in 119 patients (90.2%). There was no proven fungal infection in any patient. The number of patients with probable, possible and suspected IFI was two, two and nine, respectively. Thirty-five patients (23.8%) experienced 109 adverse events (AEs) possibly related to micafungin. No patients experienced grade IV AEs. Two patients (1.4%) discontinued micafungin administration due to adverse effects. None of the deaths were related to the study drug.

Lipid anti-lipid antibody responses correlate with disease activity in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by broad clinical manifestations including cardiovascular and renal complications with periodic disease flares and significant morbidity and mortality. One of the main contributing factors to the pathology of SLE is the accumulation and impaired clearance of immune complexes of which the principle components are host auto-antigens and antibodies. The contribution of host lipids to the formation of these autoimmune complexes remains poorly defined. The aim of the present study was to identify and analyze candidate lipid autoantigens and their corresponding anti-lipid antibody responses in a well-defined SLE patient cohort using a combination of immunological and biophysical techniques. Disease monitoring in the SLE cohort was undertaken with serial British Isles Lupus Assessment Group (BILAG) scoring. Correlations between specific lipid/anti-lipid responses were investigated as disease activity developed from active flares to quiescent during a follow up period. We report a significant negative correlation between anti-lipid antibodies for 24S-hydroxycholesterol, cardiolipin and phosphatidylserine with SLE disease activity. Taken together, these data suggest that lipid autoantigens represent a new family of biomarkers that can be employed to monitor disease activity plus the efficacy of therapeutic intervention in SLE.

Anti-lipid response in Systemic Lupus Erythematosus (44.4)

Systemic Lupus Erythematosus (SLE) is a chronic, multisystem, autoimmune disorder with a broad range of clinical presentations. One of the main factors, proposed to contribute to the development of clinical manifestations of SLE is accumulation and impaired clearance of immune complexes. The aim of the present study was to investigate lipid and anti-lipid antibody profiles in SLE patients’ plasma using ELISA and gas chromatography-mass spectrometry (GC-MS). The SLE cohort employed in this study is composed of 24 subjects and disease monitoring was undertaken with serial BILAG disease scoring. The blood was collected at three time points: at the moment of flare; and 3-months/12-months after treatment had started. For oxysterols (7α-hydroxycholesterol, 7β-hydroxycholesterol, 7-ketocholesterol) we report a trend where lipid levels and corresponding anti-lipid IgG concentrations are significantly reduced during the course of treatment. For phospholipids (oxidized phosphatidylcholine, cardiolipin) we also show high levels of anti-lipid IgG during flare or active disease. Using GC-MS and ELISA we have confirmed an association of high lipid levels and high anti-lipid IgG level with disease flare in comparison to 12 months after the commencement of treatment. We propose that auto anti-lipid IgGs should now be considered a component of the accumulated immune complexes in SLE and thus may contribute to disease pathogenesis.

Characterization of human umbilical cord lining-derived epithelial cells and transplantation potential

In this study we describe the derivation and immunological characterization of a primary epithelial cell type from the human umbilical cord membrane. These cord lining epithelial cells (CLECs) expressed and/or secreted isoforms of the nonclassical human leukocyte antigen class I (HLA-1b) glycoproteins, HLA-G and E. Conditioned media from CLECs inhibited mitogen-stimulated T-lymphocyte responses, and in a mixed leukocyte reaction (MLR) assay, cocultured CLECs inhibited allogeneic responses with a concomitant reduction in proinflammatory cytokines. Using a transwell coculture system, it was demonstrated that these immunoregulatory effects were mediated by soluble factors secreted by CLECs, in a dose-dependent manner. Functional studies using HLA-G blocking antibody showed that the effects of CLEC-secreted products could be inhibited, thus demonstrating a significant and important role for soluble HLA-G. In vivo, we show that transplanted CLECs could be maintained for extended periods in immunocompetent mice where xenorejection rapidly destroyed primary keratinocytes, a control human epithelial cell type. Additionally, CLECs delayed the rejection of keratinocytes and extended their survival when cotransplanted, indicating an ability to protect adjacent human cell types that would otherwise be rejected if transplanted alone. We also show that CLECs transduced with a modified human proinsulin gene were transplanted intraperitoneally into streptozotocin (STZ)-induced diabetic mice, resulting in significantly lower levels of serum glucose compared to control mice. This study has characterized the immunological properties of CLECs and tested a potential therapeutic application in the treatment of a type 1 diabetes mouse model.

Assessment of colorectal cancer knowledge and patient attitudes towards screening: is Ireland ready to embrace colon cancer screening?

INTRODUCTION

The level of awareness among the Irish public regarding colorectal cancer (CRC) remains uncertain. This study aimed to characterise CRC knowledge levels among a cohort of Irish patients.

METHODS

A survey evaluating CRC knowledge levels was distributed among outpatients at a gastroenterology clinic in a Dublin teaching hospital.

RESULTS

In total, 472 surveys were distributed of which 465 (98.5%) were returned. Twenty-nine percent of respondents correctly judged CRC to be the commonest cause of cancer death among the options provided while 26% correctly judged the lifetime risk of CRC; 59% underestimated and 15% overestimated the risk. Most patients (91%) were willing to pay 300 euros for a prompt colonoscopy if recommended by their physician while 7% opted to wait 6 months for a free colonoscopy.

CONCLUSIONS

There is a willingness to embrace CRC screening and to shoulder some of the financial burden that this entails.

Simultaneous thromboses of multiple coronary arteries in acute myocardial infarction

Simultaneous thrombotic occlusion of multiple coronary arteries in acute myocardial infarction is a well-recognised phenomenon. Studies have reported diffuse destabilisation of atherosclerotic plaques in patients with acute myocardial infarction, leading to the concept of "pan-coronaritis". The putative mechanism is attributed to a systemic thrombophilic and inflammatory state. We report the occurrence of this phenomenon in two middle-aged male patients.

ReoPro Observational Registry (RAPOR): insights from the multicentre use of abciximab in Asia

INTRODUCTION

The pattern of use of abciximab in real-life clinical patients undergoing percutaneous coronary intervention (PCI) in 11 high-volume centres in Singapore, Malaysia, Thailand, Philippines, India, Pakistan and Korea was prospectively examined.

METHODS

These centres enrolled 224 consecutive patients over eight months to receive abciximab during PCI for the study. The cohort consisted of 82.1 percent males, with mean age of 55 (+/- 11) years and mean weight of 67 (+/- 17) kg.

RESULTS

The use of abciximab during PCI ranged between 6.2 percent and 21.6 percent. The indications for the use of abciximab were: acute coronary syndromes (34.3 percent), complex coronary lesions (17.9 percent) and multivessel PCI (17.7 percent). Based on a risk scoring system devised for this registry, majority (60.0 percent) of the patients was considered high risk when abciximab was used. Among the patients enrolled, 36.6 percent received abciximab as a "bail-out". The overall in-hospital ischaemic event rates were low at 4.0 percent. The complication rates included major bleeding 0.7 percent, thrombocytopenia 2.7 percent and need for blood transfusion 2.8 percent. There was a trend towards a higher incidence of in-hospital non-Q myocardial infarction in the "bail-out" group (2.1 percent versus 7.3 percent, p-value equals 0.07).

CONCLUSION

Abxicimab was uncommonly used among patients (9.4 percent) undergoing PCI in this Asian region, with the operators reserving it mainly for high-risk patients.

Clinical predictors of a positive troponin T test in patients presenting with probable acute coronary syndromes

Acute coronary syndrome (ACS) patients with positive troponin T (TnT) test are at higher risk for death and myocardial reinfarction. They would significantly benefit from early aggressive pharmacologic and invasive therapy. However, TnT test is not widely available. This retrospective study of 173 patients with ACS showed: that prolonged or repetitive episodes of angina at rest in the previous 24 hours (p = 0.01) and evidence of myocardial ischaemia on ECG (p < 0.001) were associated with positive TnT tests (> or = 0.1 ng/mL). The two variables in combination showed 100% positive predictive value, facilitating early identification and streamlining of therapy.

Human VEGF165-myoblasts produce concomitant angiogenesis/myogenesis in the regenerative heart

Bioengineering the regenerative heart may provide a novel treatment for heart failure. On May 14, 2002, a 55-year-old man suffering from ischemic myocardial infarction received 25 injections carrying 465 million cGMP-produced pure myoblasts into his myocardium after coronary artery bypass grafting. As on August 28, 2002, his EKG was normal and showed no arrhythmia. His ejection fraction increased by 13%. He no longer experienced shortness of breath and angina as he did before the treatment. Three myogenesis mechanisms were elucidated with 17 human/porcine xenografts using cyclosporine as immunosuppressant. Some myoblasts developed to become cardiomyocytes. Others transferred their nuclei into host cardiomyocytes through natural cell fusion. As yet others formed skeletal myofibers with satellite cells. De novo production of contractile filaments augmented the heart contractility. Human myoblasts transduced with VEGF165 gene produced six times more capillaries in porcine myocardium than in placebo. Xenograft rejection was not observed for up to 20 weeks despite cyclosporine discontinuation at 6 weeks. Pros and cons of autografts vs. allografts are compared to guide future development of heart cell therapy.

High-sensitivity C-reactive protein is predictive of medium-term cardiac outcome in high-risk Asian patients presenting with chest pain syndrome without myocardial infarction

INTRODUCTION

High-sensitivity C-reactive protein (hs-CRP) has been shown to be predictive of cardiac events but data among Asians is comparatively few. We evaluated the role of hs-CRP in the prediction of adverse cardiac outcome in a cohort of high-risk patients presenting with chest pain syndrome without myocardial infarction (MI).

MATERIALS AND METHODS

Three hundred and forty-seven patients were prospectively recruited over an 18-month period and patients with MI as documented by serial electrocardiogram abnormalities, and creatinine kinase or troponin elevation were excluded. Mean follow-up duration was 901 +/- 306 days. Kaplan-Meier and Cox proportional hazards modelling were used to evaluate outcome and determine association with predictor variables.

RESULTS

The composite primary endpoint of cardiac mortality, non-fatal MI, cardiac failure or coronary revascularisation procedure (coronary artery bypass grafting or angioplasty) unrelated to the index admission was reached in 37 patients. History of previous MI (P = 0.002), presence of at least 1 coronary artery with > or =50% stenosis (P = 0.028) and elevated hs-CRP levels were associated with an adverse cardiac outcome (P = 0.001 for CRP in the upper quartile, and 0.002 for CRP > or = 1mg/L, respectively). None of the traditional cardiovascular risk factors (hypertension, diabetes mellitus, dyslipidaemia, significant family history, smoking, male gender and increased age) was predictive. Multivariate modelling showed elevated hs-CRP to confer the highest risk for an adverse cardiac outcome (P <0.001).

CONCLUSION

Hs-CRP is useful in further stratifying high-risk multi-ethnic patients presenting with chest pain despite no evidence of MI. Close follow-up and aggressive management of these patients may be warranted.

The impact of diabetes mellitus on the prognostic value of a normal dobutamine stress echocardiogram in patients with intermediate to high cardiovascular risk

INTRODUCTION

There is currently limited data on the prognostic value of a normal dobutamine stress echocardiogram (DSE) in patients with intermediate to high cardiovascular risk. The impact of diabetes mellitus, recently recognised as a cardiovascular risk-equivalent, has not been previously evaluated. This study aims to determine the prognostic value of a normal DSE in these patients.

METHODS

The study population includes all patients with two cardiovascular risk factors or diabetes mellitus and a normal DSE (baseline and peak stress) with three months follow-up. A total of 122 patients (47 females, 75 males; mean age 59.6 years) were recruited. Impact of diabetes mellitus on subsequent cardiovascular events was determined.

RESULTS

Diabetes mellitus was present in 32.8 percent, hypertension in 72.1 percent, smoking in 27.0 percent, family history of premature coronary artery disease in 15.6 percent, and hypercholesterolemia in 66.4 percent. On follow-up until 6.4 years (mean 4.1 years), there were four myocardial infarctions (0.8 percent per patient/year) and five revascularisation procedures (1.0 percent per patient/year). The majority of adverse events occurred among patients with diabetes mellitus (three out of four myocardial infarctions; four out of five revascularisations). Diabetes mellitus independently predicted subsequent cardiac events on both univariate and multivariate analyses (p value is equal to 0.015 and 0.011, respectively). Presence of diabetes mellitus also conferred a worse outcome on survival analysis (p value is equivalent to 0.0046).

CONCLUSION

The presence of diabetes mellitus adversely affects clinical outcome despite a normal DSE. Patients without diabetes mellitus, but with intermediate to high cardiovascular risk, and a normal DSE have a better medium term outcome.

Lower trunk muscle activity during the tennis serve

Prior electromyographic (EMG) analyses of the tennis serve have focused on the muscles in the hitting arm and shoulder region. This preliminary study aimed to examine the muscle activation patterns of selected lower trunk muscles during three different types of tennis serve--flat, topspin, and slice. Five male highly skilled tennis players completed 10 trials for each type of serve. Surface EMG electrodes were used to monitor the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and lumbar erector spinae (ES) muscles. For each subject, the two trials with the highest self-reported ratings were analysed. Average EMG levels during each phase of a tennis serve for each muscle were analysed using a non-parametric ANOVA design. No major differences in muscle activation pattern were found across different serve types, and bilateral differences in muscle activation were more pronounced in RA and EO than in IO and ES muscles. The abdominal muscles were more active in the topspin than in the other two types of serves during the upward swing of the racket. An appreciable amount of abdominal/low back and bilateral co-activation was observed during certain phases of the serve. The co-activation of lower trunk muscles may help to stabilise the lumbar spine during the arch back and forward swing phases of the serve. The results reinforce the importance of abdominal and low back exercises in the strength and rehabilitation programs designed for tennis players.

Fatal pulmonary haemorrhage with the combined use of abciximab and fibrinolytic agent

The increased bleeding risk associated with the use of abciximab has been well reported. The risk appears to be amplified when abciximab is administered concurrently with a fibrinolytic agent. We report and review the literature on the occurrence of a case of fatal pulmonary haemorrhage, a rare bleeding complication, in a patient who received both these drugs.

A case of broken heart from blunt trauma

A young man with blunt chest trauma presented acutely in shock as a result of cardiac rupture causing acute bloody tamponade. We discuss the clinical presentation, the importance of rapid and accurate diagnosis and management of such cases.

Recurrent self-limited fungemia caused by Yarrowia lipolytica in a patient with acute myelogenous leukemia

Yarrowia lipolytica is a weakly pathogenic yeast that is rarely isolated from the blood. We observed transient recurrent catheter-related fungemia attributable to this organism in a leukemic patient. The fungemia and accompanying fever subsided spontaneously. The data suggest that it might be possible to withhold specific treatment for Y. lipolytica fungemia even in an immunocompromised patient.

Tissue-engineered growth of bone by marrow cell transplantation using porous calcium metaphosphate matrices

In this study we investigated not only osteoblastic cell proliferation and differentiation on the surface of calcium metaphosphate (CMP) matrices in vitro but also bone formation by ectopic implantation of these cell-matrix constructs in athymic mice in vivo. Interconnected porous CMP matrices with pores 200 microm in size were prepared to use as scaffolds for rat-marrow stromal-cell attachment. Cell-matrix constructs were cultured in vitro, and cell proliferation and ALPase activities were monitored for 56 days. In addition to their being cultured in vitro, cell-matrix constructs were implanted into subcutaneous sites of athymic mice. In vitro these porous CMP matrices supported the proliferation of osteoblastic cells as well as their differentiation, as indicated by high ALPase activity. In vivo the transplanted marrow cells gave rise to bone tissues in the pores of the CMP matrices. A small amount of woven bone formation was detected first at 4 weeks; osteogenesis progressed vigorously with time, and thick lamellar bones that had been remodeled were observed at 12 weeks. These findings demonstrate the potential for using a porous CMP matrix as a biodegradable scaffold ex vivo along with attached marrow-derived mesenchymal cells for transplantation into a site for bone regeneration in vivo.

Can bone turnover markers correlate bone mass at the hip and spine according to menopausal period?

Changes in bone turnover with years since menopause (YSM) are responsible for bone loss and play a major role in osteoporosis. Although single measurements of the bone turnover marker appear unlikely to be clinically useful in predicting bone mineral density, the usefulness of these measurements in relation to the YSM has not been well established. The establishment of this relationship was the aim of this study. To address this issue, we have measured a battery of sensitive and specific markers of bone turnover in 272 women postmenopausal from -5 to 15 a, and the data was correlated with bone mineral density (BMD) at different skeletal sites measured utilizing dual-energy X-ray absorptiometry (DXA). Bone formation was assessed by serum osteocalcin (OC), and bone resorption by Pyr and D-pyr. The three markers and BMD were compared between the groups (YSM). Among the three markers, only Pyr exhibited a significant difference between pre and postmenopausal groups. In the aspect of correlation between bone turnover marker and BMD according to the groups (YSM), we found negative strong correlations between the BMD of lumbar spine (L2-4) vs. Pyr (P=0.01, r=-0.75) in the premenopausal group (-5 approximately 0 YSM), and we found negative correlation between the BMD of L2-4 vs. osteocalcin (P=0.05, r=-0.2 and P=0.01, r=-4).44) in the postmenopause groups (0 approximately 5 and 5 approximately 10 YSM). We concluded that Pyr in women -5 approximately 0 YSM and osteocalcin in women 0 approximately 10 YSM displayed negative correlation with BMD of L2-4.

Usefulness of ST elevation II/III ratio and ST deviation in lead I for identifying the culprit artery in inferior wall acute myocardial infarction

In a study of 92 patients presenting with inferior wall acute myocardial infarction, the infarct-related artery was the right coronary artery in 72 patients (78%) and the left circumflex artery in 20 (22%). An ST II/III ratio of 1 or an isoelectric ST in lead I are sensitive and specific markers of left circumflex artery occlusion, whereas an ST II/III ratio <1 (ST elevation in lead III >II) or ST depression in lead I are sensitive and specific markers of right coronary artery occlusion.