Publications by authors named "Rajasekaran T"

AA5083 is an alloy of military-grade aluminum used to make lightweight combat vehicles. Combining this material with traditional welding methods results in the formation of grain agglomerations, alloy separation, porosity, and pores. To overcome these shortcomings, Friction stir welding was utilized.

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Background: In early-stage non-small cell lung cancer (NSCLC), recurrence is frequently observed. Circulating tumor DNA (ctDNA) has emerged as a noninvasive tool to risk stratify patients for recurrence after curative intent therapy. This study aimed to risk stratify patients with early-stage NSCLC via a personalized, tumor-informed multiplex polymerase chain reaction (mPCR) next-generation sequencing assay.

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Background: The geriatric oncology population tends to be complex because of multimorbidity, functional and cognitive decline, malnutrition and social frailty. Prognostic indices for predicting survival of elderly cancer patients to guide treatment remain scarce. A nomogram based on all domains of the geriatric assessment was previously developed at the National Cancer Centre Singapore (NCCS) to predict overall survival (OS) in elderly cancer patients.

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Introduction: This systematic review evaluated treatment patterns and guidelines in advanced/metastatic and adjuvant renal cell carcinoma (RCC) in the Asia-Pacific region.

Areas Covered: Embase, PubMed, and congresses were searched for observational studies and guidelines in accordance with PRISMA. Records published during 2016-2021 (2019-2021 for congresses) were included.

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Objectives: Real-world uptake of treatment intensification (TI) with novel hormonal agents (NHA) or chemotherapy as treatment of metastatic prostate cancer remains low outside of trial settings. We aim to report the prescription patterns and treatment outcomes of de novo metastatic hormone-sensitive prostate cancer (mHSPC) in a tertiary institution.

Methods: This is a retrospective cohort study using real-world data from a prospectively maintained prostate cancer registry.

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Background: Osimertinib is a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) approved for use in EGFR-mutant lung cancer. We examined its performance in the second/subsequent line after resistance to first- and second-generation (1/2G) EGFR-TKI.

Methods: We reviewed electronic records of 202 patients who received osimertinib from July 2015 to January 2019 in the second/subsequent line after progression on prior EGFR-TKI.

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We recently described a chemical strategy to pre-organize a trinucleotide subunit in a conformation suitable for Watson-Crick base pairing for modulating the binding kinetics of single-stranded oligonucleotides (ONs) using bis-phosphonate esters bridging hydrocarbon tethers to provide 11- and 15-membered macrocyclic analogues. In this manuscript, we describe the synthesis of all eight P-stereoisomers of macrocyclic 12-, 13-, 14-, and 16-membered hydrocarbon-bridged nucleotide trimers, their incorporation into ONs, and biophysical characterization of the modified ONs. The size of the macrocyclic tether and configuration at phosphorus had profound effects on hybridization kinetics.

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Prostate cancer is a disease of older adults that has undergone a significant therapeutic paradigm shift in the last decade with the emergence of novel androgen receptor pathway inhibitors (ARPis). One of the more commonly used ARPis is enzalutamide. This drug, along with darolutamide and apalutamide, initially received approvals in the metastatic castrate-resistant prostate cancer setting but is now utilized frequently in the metastatic castrate-sensitive and non-metastatic castration-resistant settings.

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Aim: To determine the prognostic value of programmed death-ligand 1 (PD-L1) score in early-stage epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC), contrasted against EGFR-wildtype NSCLC.

Methods: Consecutive patients with Stage IA-IIIA NSCLC diagnosed 1st January 2010-31st December 2019 at National Cancer Centre Singapore with evaluable EGFR and PD-L1 status were included. Co-primary end-points were 2-year disease-free survival (DFS) and 5-year overall survival (OS) by Kaplan-Meier method.

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Introduction: Although immune checkpoint inhibitors (ICIs) have dramatically improved outcomes for nononcogene-addicted NSCLC, monotherapy with programmed cell death protein-1 (PD1) inhibition has been associated with low efficacy in the EGFR-mutant setting. Given the potential for synergism with combination checkpoint blockade, we designed a trial to test the activity of combination nivolumab (N)-ipilimumab (NI) in EGFR-mutant NSCLC.

Methods: This is a randomized phase 2 study (NCT03091491) of N versus NI combination in EGFR tyrosine kinase inhibitor (TKI)-resistant NSCLC, with crossover permitted on disease progression.

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Purpose: -altered non-small-cell lung cancer (NSCLC) represents a diverse subgroup, including mutations, amplifications, and overexpression. However, exon 20 insertion mutations are emerging as a distinct molecular subtype with expanding therapeutic options. We describe the molecular epidemiology and genomic features of -altered NSCLC in an Asian tertiary cancer center.

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The binding affinity of therapeutic oligonucleotides (ONs) for their cognate RNA is determined by the rates of association () and dissociation (). Single-stranded ONs are highly flexible and can adopt multiple conformations in solution, some of which may not be conducive for hybridization. We investigated if restricting rotation around the sugar-phosphate backbone, by tethering two adjacent backbone phosphonate esters using hydrocarbon bridges, can modulate hybridization kinetics of the modified ONs for complementary RNA.

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Aim: To evaluate the levels of leptin in gingival crevicular fluid (GCF) during orthodontic tooth movement and to find the role of leptin as a mediator for tooth movement.

Materials And Methods: GCF was collected from 25 subjects and the levels of leptin in it were measured. Sample (A) pretreatment, (B) 6 h after applying retractive orthodontic force from right side canine, (C) without retractive force from left side canine, and after 21 days from right canine (D), and left canine (E).

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Importance: The recently published ADAURA study has posed a significant dilemma for clinicians in selecting patients for adjuvant osimertinib. Risk factors for recurrence in early-stage epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC) also remain undefined.

Objective: To determine clinicopathologic characteristics and recurrence patterns of resected early-stage EGFR-positive NSCLC, using wildtype EGFR as a comparator cohort, and identify features associated with recurrence.

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Purpose: Despite the established role of EGFR tyrosine kinase inhibitors (TKIs) in -mutated NSCLC, drug resistance inevitably ensues, with a paucity of treatment options especially in -negative resistance.

Experimental Design: We performed whole-exome and transcriptome analysis of 59 patients with first- and second-generation EGFR TKI-resistant metastatic -mutated NSCLC to characterize and compare molecular alterations mediating resistance in T790M-positive (T790M) and -negative (T790M) disease.

Results: Transcriptomic analysis revealed ubiquitous loss of adenocarcinoma lineage gene expression in T790M tumors, orthogonally validated using multiplex IHC.

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Introduction: RET rearrangements are an emerging targetable oncogenic fusion driver in NSCLC. However, the natural history of disease and activity of different classes of systemic therapy remain to be defined. Furthermore, molecular testing for RET is not yet routine, and the optimal method of testing is unclear.

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Purpose: High-quality end-of-life cancer care requires oncologists to communicate effectively and patients/caregivers to be participatory. However, most communication interventions target either but not both. We aimed to pilot a potentially disseminable combined oncologist-patient/caregiver intervention to improve oncologist empathic responses, discussions of prognosis and goals of care, and patient/caregiver participation.

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Objectives: There is an expanding list of therapeutically relevant biomarkers for non-small cell lung cancer (NSCLC), and molecular profiling at diagnosis is paramount. Tissue attrition in scaling traditional single biomarker assays from small biopsies is an increasingly encountered problem. We sought to compare the performance of targeted next-generation sequencing (NGS) panels with traditional assays and correlate the mutational landscape with PD-L1 status in Singaporean patients.

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Introduction: Several small studies have reviewed the efficacy of abiraterone acetate plus prednisolone (AAP) in clinical practice outside a trial setting. We report the largest cohort study of clinical outcomes in metastatic castrate-resistant prostate cancer (mCRPC) patients treated with AAP in a multicenter multiracial clinical setting.

Methods: A retrospective analysis on mCRPC patients treated at four tertiary hospitals in Singapore from 2012 to 2017 was conducted.

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Purpose: Mesenchymal epithelial transition factor ( MET) activation has been implicated as an oncogenic driver in epidermal growth factor receptor ( EGFR)-mutant non-small-cell lung cancer (NSCLC) and can mediate primary and secondary resistance to EGFR tyrosine kinase inhibitors (TKI). High copy number thresholds have been suggested to enrich for response to MET inhibitors. We examined the clinical relevance of MET copy number gain (CNG) in the setting of treatment-naive metastatic EGFR-mutant-positive NSCLC.

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Metronomic administration of chemotherapy has long been recognized as having a different biological effect from maximal tolerated dose (MTD) administration. Preclinical studies have demonstrated these differences quite elegantly and many clinical trials have also demonstrated reproducible activity albeit small, in varied solid malignancies even in patients who were heavily pretreated. However, the concept of metronomic chemotherapy has been plagued by lack of a clear definition resulting in the published literature that is rather varied and confusing.

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Purpose: Elderly cancer patients are at increased risk for malnutrition. We aim to identify comprehensive geriatric assessment (CGA) based clinical factors associated with increased nutritional risk and develop a clinical scoring system to identify nutritional risk in elderly cancer patients.

Patients And Methods: CGA data was collected from 249 Asian patients aged 70 years or older.

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Objective: This study aims to identify Comprehensive Geriatric Assessment (CGA) based risk factors to help predict caregiver burden among elderly patients with cancer.

Materials And Method: The study evaluated 249 patients newly diagnosed with cancer, aged 70years and above, who attended the geriatric oncology clinic at the National Cancer Centre Singapore between 2007 and 2010.

Results: Out of 249 patients, 244 patients had information available on family caregiver burden and were analysed.

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Four structures of oxoindolyl α-hydroxy-β-amino acid derivatives, namely, methyl 2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-methoxy-2-phenylacetate, C24H28N2O6, (I), methyl 2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-ethoxy-2-phenylacetate, C25H30N2O6, (II), methyl 2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-[(4-methoxybenzyl)oxy]-2-phenylacetate, C31H34N2O7, (III), and methyl 2-[(anthracen-9-yl)methoxy]-2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-phenylacetate, C38H36N2O6, (IV), have been determined. The diastereoselectivity of the chemical reaction involving α-diazoesters and isatin imines in the presence of benzyl alcohol is confirmed through the relative configuration of the two stereogenic centres. In esters (I) and (III), the amide group adopts an anti conformation, whereas the conformation is syn in esters (II) and (IV).

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