Patient-specific computational models predict prognosis in B cell lymphoma by quantifying pro-proliferative and anti-apoptotic signatures from genetic sequencing data.

Genetic heterogeneity and co-occurring driver mutations impact clinical outcomes in blood cancers, but predicting the emergent effect of co-occurring mutations that impact multiple complex and interacting signalling networks is challenging. Here, we used mathematical models to predict the impact of co-occurring mutations on cellular signalling and cell fates in diffuse large B cell lymphoma and multiple myeloma. Simulations predicted adverse impact on clinical prognosis when combinations of mutations induced both anti-apoptotic (AA) and pro-proliferative (PP) signalling. We integrated patient-specific mutational profiles into personalised lymphoma models, and identified patients characterised by simultaneous upregulation of anti-apoptotic and pro-proliferative (AAPP) signalling in all genomic and cell-of-origin classifications (8-25% of patients). In a discovery cohort and two validation cohorts, patients with upregulation of neither, one (AA or PP), or both (AAPP) signalling states had good, intermediate and poor prognosis respectively. Combining AAPP signalling with genetic or clinical prognostic predictors reliably stratified patients into striking prognostic categories. AAPP patients in poor prognosis genetic clusters had 7.8 months median overall survival, while patients lacking both features had 90% overall survival at 120 months in a validation cohort. Personalised computational models enable identification of novel risk-stratified patient subgroups, providing a valuable tool for future risk-adapted clinical trials.

A Modular Communicative Leadless Pacing-Defibrillator System.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (ICD) is associated with fewer lead-related complications than a transvenous ICD; however, the subcutaneous ICD cannot provide bradycardia and antitachycardia pacing. Whether a modular pacing-defibrillator system comprising a leadless pacemaker in wireless communication with a subcutaneous ICD to provide antitachycardia and bradycardia pacing is safe remains unknown. METHODS: We conducted a multinational, single-group study that enrolled patients at risk for sudden death from ventricular arrhythmias and followed them for 6 months after implantation of a modular pacemaker-defibrillator system. The safety end point was freedom from leadless pacemaker-related major complications, evaluated against a performance goal of 86%. The two primary performance end points were successful communication between the pacemaker and the ICD (performance goal, 88%) and a pacing threshold of up to 2.0 V at a 0.4-msec pulse width (performance goal, 80%). RESULTS: We enrolled 293 patients, 162 of whom were in the 6-month end-point cohort and 151 of whom completed the 6-month follow-up period. The mean age of the patients was 60 years, 16.7% were women, and the mean (±SD) left ventricular ejection fraction was 33.1±12.6%. The percentage of patients who were free from leadless pacemaker-related major complications was 97.5%, which exceeded the prespecified performance goal. Wireless-device communication was successful in 98.8% of communication tests, which exceeded the prespecified goal. Of 151 patients, 147 (97.4%) had pacing thresholds of 2.0 V or less, which exceeded the prespecified goal. The percentage of episodes of arrhythmia that were successfully terminated by antitachycardia pacing was 61.3%, and there were no episodes for which antitachycardia pacing was not delivered owing to communication failure. Of 162 patients, 8 died (4.9%); none of the deaths were deemed to be related to arrhythmias or the implantation procedure. CONCLUSIONS: The leadless pacemaker in wireless communication with a subcutaneous ICD exceeded performance goals for freedom from major complications related to the leadless pacemaker, for communication between the leadless pacemaker and subcutaneous ICD, and for the percentage of patients with a pacing threshold up to 2.0 V at a 0.4-msec pulse width at 6 months. (Funded by Boston Scientific; MODULAR ATP ClinicalTrials.gov NCT04798768.).

A therapeutic antibody targeting annexin-A1 inhibits cancer cell growth in vitro and in vivo.

In this study we conducted the first investigation to assess the efficacy of a novel therapeutic antibody developed to target annexin-A1 (ANXA1). ANXA1 is an immunomodulatory protein which has been shown to be overexpressed in, and promote the development and progression of, several cancer types. In particular, high ANXA1 expression levels correlate with poorer overall survival in pancreatic and triple-negative breast cancers, two cancers with considerable unmet clinical need. MDX-124 is a humanised IgG1 monoclonal antibody which specifically binds to ANXA1 disrupting its interaction with formyl peptide receptors 1 and 2 (FPR1/2). Here we show that MDX-124 significantly reduced proliferation (p < 0.013) in a dose-dependent manner across a panel of human cancer cell lines expressing ANXA1. The anti-proliferative effect of MDX-124 is instigated by arresting cell cycle progression with cancer cells accumulating in the G1 phase of the cell cycle. Furthermore, MDX-124 significantly inhibited tumour growth in both the 4T1-luc triple-negative breast and Pan02 pancreatic cancer syngeneic mouse models (p < 0.0001). These findings suggest ANXA1-targeted therapy is a viable and innovative approach to treat tumours which overexpress ANXA1.

Expression and Activity of the NF-κB Subunits in Chronic Lymphocytic Leukaemia: A Role for RelB and Non-Canonical Signalling.

BACKGROUND: Canonical NF-κB signalling by p65 (RelA) confers chemo-resistance and poor survival in chronic lymphocytic leukaemia (CLL). The role of non-canonical NF-κB signalling (leading to RelB and p52 subunit activation) in CLL is less understood, but given its importance in other B-cell tumour types, we theorised that RelB and p52 may also contribute to the pathology of CLL. METHODS: DNA binding activity of all five NF-kB subunits, p65, p50, RelB, p52, and c-Rel, was quantified using ELISA and correlated to ex vivo chemoresistance, CD40L-stimulated signalling (to mimic the lymph node microenvironment), and clinical data. RESULTS: Importantly, we show for the first time that high basal levels of RelB DNA binding correlate with nuclear RelB protein expression and are associated with del(11q), ATM dysfunction, unmutated IGHV genes, and shorter survival. High levels of nuclear p65 are prevalent in del(17p) cases (including treatment-naïve patients) and also correlate with the outcome. CD40L-stimulation resulted in rapid RelB activation, phosphorylation and processing of p100, and subsequent CLL cell proliferation. CONCLUSIONS: These data highlight a role for RelB in driving CLL cell tumour growth in a subset of patients and therefore strategies designed to inhibit non-canonical NF-κB signalling represent a novel approach that will have therapeutic benefit in CLL.

Computational modeling of DLBCL predicts response to BH3-mimetics.

In healthy cells, pro- and anti-apoptotic BCL2 family and BH3-only proteins are expressed in a delicate equilibrium. In contrast, this homeostasis is frequently perturbed in cancer cells due to the overexpression of anti-apoptotic BCL2 family proteins. Variability in the expression and sequestration of these proteins in Diffuse Large B cell Lymphoma (DLBCL) likely contributes to variability in response to BH3-mimetics. Successful deployment of BH3-mimetics in DLBCL requires reliable predictions of which lymphoma cells will respond. Here we show that a computational systems biology approach enables accurate prediction of the sensitivity of DLBCL cells to BH3-mimetics. We found that fractional killing of DLBCL, can be explained by cell-to-cell variability in the molecular abundances of signaling proteins. Importantly, by combining protein interaction data with a knowledge of genetic lesions in DLBCL cells, our in silico models accurately predict in vitro response to BH3-mimetics. Furthermore, through virtual DLBCL cells we predict synergistic combinations of BH3-mimetics, which we then experimentally validated. These results show that computational systems biology models of apoptotic signaling, when constrained by experimental data, can facilitate the rational assignment of efficacious targeted inhibitors in B cell malignancies, paving the way for development of more personalized approaches to treatment.

NF-κB fingerprinting reveals heterogeneous NF-κB composition in diffuse large B-cell lymphoma.

Introduction: Improving treatments for Diffuse Large B-Cell Lymphoma (DLBCL) is challenged by the vast heterogeneity of the disease. Nuclear factor-κB (NF-κB) is frequently aberrantly activated in DLBCL. Transcriptionally active NF-κB is a dimer containing either RelA, RelB or cRel, but the variability in the composition of NF-κB between and within DLBCL cell populations is not known. Results: Here we describe a new flow cytometry-based analysis technique termed "NF-κB fingerprinting" and demonstrate its applicability to DLBCL cell lines, DLBCL core-needle biopsy samples, and healthy donor blood samples. We find each of these cell populations has a unique NF-κB fingerprint and that widely used cell-of-origin classifications are inadequate to capture NF-κB heterogeneity in DLBCL. Computational modeling predicts that RelA is a key determinant of response to microenvironmental stimuli, and we experimentally identify substantial variability in RelA between and within ABC-DLBCL cell lines. We find that when we incorporate NF-κB fingerprints and mutational information into computational models we can predict how heterogeneous DLBCL cell populations respond to microenvironmental stimuli, and we validate these predictions experimentally. Discussion: Our results show that the composition of NF-κB is highly heterogeneous in DLBCL and predictive of how DLBCL cells will respond to microenvironmental stimuli. We find that commonly occurring mutations in the NF-κB signaling pathway reduce DLBCL's response to microenvironmental stimuli. NF-κB fingerprinting is a widely applicable analysis technique to quantify NF-κB heterogeneity in B cell malignancies that reveals functionally significant differences in NF-κB composition within and between cell populations.

Developing a post-myocardial infarction medicines optimisation clinic: core competencies for upskilling pharmacists and initial patient feedback.

BACKGROUND: Medicines optimisation and adherence support are essential to secondary prevention after myocardial infarction (MI). Following successful implementation of a consultant pharmacist-led post-MI medicines optimisation clinic, the service was expanded by training advanced clinical pharmacists to manage clinics (with appropriate multidisciplinary team support). METHODS: Key steps in the development process were: definition of a key competency framework based on relevant qualifications and experience, knowledge, skills and clinic management practicalities; creation and enaction of trainee-specific development plans to address gaps (including independent learning, teaching from multidisciplinary colleagues and shadowing in clinics); establishment of relevant protocols and proformas to ensure consistent standards (eg, a patient self-reporting tool for identifying adherence barriers, consultation proforma, directory of clinical parameters and pathway for onward referral when needed); phased clinic roll-out, initially under supervision; and gathering of feedback from patients and colleagues. Clinic letters from 50 attending patients were reviewed to quantify resulting interventions; the first 50 anonymously completed patient feedback questionnaires were also analysed. RESULTS: Expansion of the service initially doubled capacity. A review of clinic letters from attending patients demonstrated that various interventions were recommended, including further investigations, medication changes, lifestyle adjustments and onward referrals. Most respondents to the patient feedback questionnaire thought the clinic was patient friendly and welcoming (n=48/50; 96%); felt listened to (n=48/50; 96%); considered that adequate explanation was given (n=47/50; 94%); and felt clear plans were provided (n=45/49; 92%). Most agreed that it was valuable (n=44/50; 88%), and the mean rating was 4.48 (on a scale of 1 (very poor) to 5 (excellent)). CONCLUSIONS: A person-centred post-MI medicines optimisation service was successfully delivered by appropriately trained advanced cardiology pharmacists. A structured competency framework and training programme were required, but once completed, the clinic was highly valued by patients. A similar model could be rolled out elsewhere with adaption to local requirements.

NF-kB and the CLL microenvironment.

Chronic lymphocytic leukemia (CLL) is the most prevalent type of leukemia in the western world. Despite the positive clinical effects of new targeted therapies, CLL still remains an incurable and refractory disease and resistance to treatments are commonly encountered. The Nuclear Factor-Kappa B (NF-κB) transcription factor has been implicated in the pathology of CLL, with high levels of NF-κB associated with disease progression and drug resistance. This aberrant NF-κB activation can be caused by genetic mutations in the tumor cells and microenvironmental factors, which promote NF-κB signaling. Activation can be induced via two distinct pathways, the canonical and non-canonical pathway, which result in tumor cell proliferation, survival and drug resistance. Therefore, understanding how the CLL microenvironment drives NF-κB activation is important for deciphering how CLL cells evade treatment and may aid the development of novel targeting therapeutics. The CLL microenvironment is comprised of various cells, including nurse like cells, mesenchymal stromal cells, follicular dendritic cells and CD4+ T cells. By activating different receptors, including the B cell receptor and CD40, these cells cause overactivity of the canonical and non-canonical NF-κB pathways. Within this review, we will explore the different components of the CLL microenvironment that drive the NF-κB pathway, investigating how this knowledge is being translated in the development of new therapeutics.

Synthesis and Characterization of NUC-7738, an Aryloxy Phosphoramidate of 3'-Deoxyadenosine, as a Potential Anticancer Agent.

3'-Deoxyadenosine (3'-dA, Cordycepin, 1) is a nucleoside analogue with anticancer properties, but its clinical development has been hampered due to its deactivation by adenosine deaminase (ADA) and poor cellular uptake due to low expression of the human equilibrative transporter (hENT1). Here, we describe the synthesis and characterization of NUC-7738 (7a), a 5'-aryloxy phosphoramidate prodrug of 3'-dA. We show in vitro evidence that 7a is an effective anticancer drug in a panel of solid and hematological cancer cell lines, showing its preferential cytotoxic effects on leukemic stem cells. We found that unlike 3'-dA, the activity of 7a was independent of hENT1 and kinase activity. Furthermore, it was resistant to ADA metabolic deactivation. Consistent with these findings, 7a showed increased levels of intracellular 3'-deoxyadenosine triphosphate (3'-dATP), the active metabolite. Mechanistically, levels of intracellular 3'-dATP were strongly associated with in vitro potency. NUC-7738 is now in Phase II, dose-escalation study in patients with advanced solid tumors.

UK Expert Consensus Statement for the Optimal Use and Clinical Utility of Leadless Pacing Systems on Behalf of the British Heart Rhythm Society.

Pacemakers are a key technology in the treatment of bradyarrhythmias. Leadless pacemakers (LP) were introduced to address limitations of transvenous devices. However, guidelines and other restrictions have led to LPs becoming niche products. The aim of this consensus statement was to determine the strength of opinion of UK implantation experts as to how LPs can be more optimally used. Using a modified Delphi approach, a panel of LP experts developed 36 statements that were used to form a survey that was distributed to LP implanters in the UK. Stopping criteria included a 3-month window for response, a minimum 25% response rate and at least 75% of statements achieving the threshold for consensus (agreed at 66%). In all, 31 of 36 statements reached consensus, and 23 of these achieved ≥90% agreement. Five statements did not achieve consensus. On the basis of these results, seven recommendations were proposed. The implementation of these recommendations may increase the use of LPs, with the aim of improving patient outcomes.

DNA sequence-selective G-A cross-linking ADC payloads for use in solid tumour therapies.

Antibody-Drug Conjugates (ADCs) are growing in importance for the treatment of both solid and haematological malignancies. There is a demand for new payloads with novel mechanisms of action that may offer enhanced therapeutic efficacy, especially in patients who develop resistance. We report here a class of Cyclopropabenzindole-Pyridinobenzodiazepine (CBI-PDD) DNA cross-linking payloads that simultaneously alkylate guanine (G) and adenine (A) bases in the DNA minor groove with a defined sequence selectivity. The lead payload, FGX8-46 (6), produces sequence-selective G-A cross-links and affords cytotoxicity in the low picomolar region across a panel of 11 human tumour cell lines. When conjugated to the antibody cetuximab at an average Drug-Antibody Ratio (DAR) of 2, an ADC is produced with significant antitumour activity at 1 mg/kg in a target-relevant human tumour xenograft mouse model with an unexpectedly high tolerability (i.e., no weight loss observed at doses as high as 45 mg/kg i.v., single dose).

Elucidation of Focal Adhesion Kinase as a Modulator of Migration and Invasion and as a Potential Therapeutic Target in Chronic Lymphocytic Leukemia.

The retention and re-migration of Chronic Lymphocytic Leukemia cells into cytoprotective and proliferative lymphoid niches is thought to contribute to the development of resistance, leading to subsequent disease relapse. The aim of this study was to elucidate the molecular processes that govern CLL cell migration to elicit a more complete inhibition of tumor cell migration. We compared the phenotypic and transcriptional changes induced in CLL cells using two distinct models designed to recapitulate the peripheral circulation, CLL cell migration across an endothelial barrier, and the lymph node interaction between CLL cells and activated T cells. Initially, CLL cells were co-cultured with CD40L-expressing fibroblasts and exhibited an activated B-cell phenotype, and their transcriptional signatures demonstrated the upregulation of pro-survival and anti-apoptotic genes and overrepresentation of the NF-κB signaling pathway. Using our dynamic circulating model, we were able to study the transcriptomics and miRNomics associated with CLL migration. More than 3000 genes were altered when CLL cells underwent transendothelial migration, with an overrepresentation of adhesion and cell migration gene sets. From this analysis, an upregulation of the FAK signaling pathway was observed. Importantly, PTK2 (FAK) gene expression was significantly upregulated in migrating CLL cells (PTK2 Fold-change = 4.9). Here we demonstrate that TLR9 agonism increased levels of p-FAK (p ≤ 0.05), which could be prevented by pharmacological inhibition of FAK with defactinib (p ≤ 0.01). Furthermore, a reduction in CLL cell migration and invasion was observed when FAK was inhibited (p ≤ 0.0001), supporting a role for FAK in both CLL migration and tissue invasion. When taken together, our data highlights the potential for combining FAK inhibition with current targeted therapies as a more effective treatment regime for CLL.

Targeting the Non-Canonical NF-κB Pathway in Chronic Lymphocytic Leukemia and Multiple Myeloma.

In this study, we evaluated an NF-κB inducing kinase (NIK) inhibitor, CW15337, in primary chronic lymphocytic leukemia (CLL) cells, CLL and multiple myeloma (MM) cell lines and normal B- and T-lymphocytes. Basal NF-κB subunit activity was characterized using an enzyme linked immunosorbent assay (ELISA), and the effects of NIK inhibition were then assessed in terms of cytotoxicity and the expression of nuclear NF-κB subunits following monoculture and co-culture with CD40L-expressing fibroblasts, as a model of the lymphoid niche. CW15337 induced a dose-dependent increase in apoptosis, and nuclear expression of the non-canonical NF-κB subunit, p52, was correlated with sensitivity to CW15337 (p = 0.01; r2 = 0.39). Co-culture on CD40L-expressing cells induced both canonical and non-canonical subunit expression in nuclear extracts, which promoted in vitro resistance against fludarabine and ABT-199 (venetoclax) but not CW15337. Furthermore, the combination of CW15337 with fludarabine or ABT-199 showed cytotoxic synergy. Mechanistically, CW15337 caused the selective inhibition of non-canonical NF-κB subunits and the transcriptional repression of BCL2L1, BCL2A1 and MCL1 gene transcription. Taken together, these data suggest that the NIK inhibitor, CW15337, exerts its effects via suppression of the non-canonical NF-κB signaling pathway, which reverses BCL2 family-mediated resistance in the context of CD40L stimulation.

TP53 Mutations with Low Variant Allele Frequency Predict Short Survival in Chronic Lymphocytic Leukemia.

PURPOSE: In chronic lymphocytic leukemia (CLL), TP53 mutations are associated with reduced survival and resistance to standard chemoimmunotherapy (CIT). Nevertheless, the clinical impact of subclonal TP53 mutations below 10% to 15% variant allele frequency (VAF) remains unclear. EXPERIMENTAL DESIGN: Using a training/validation approach, we retrospectively analyzed the clinical and biological features of TP53 mutations above (high-VAF) or below (low-VAF) the previously reported 10.0% VAF threshold, as determined by deep next-generation sequencing. Clinical impact of low-VAF TP53 mutations was also confirmed in a cohort (n = 251) of CLL treated with fludarabine-cyclophosphamide-rituximab (FCR) or FCR-like regimens from two UK trials. RESULTS: In the training cohort, 97 of 684 patients bore 152 TP53 mutations, while in the validation cohort, 71 of 536 patients had 109 TP53 mutations. In both cohorts, patients with the TP53 mutation experienced significantly shorter overall survival (OS) than TP53 wild-type patients, regardless of the TP53 mutation VAF. By combining TP53 mutation and 17p13.1 deletion (del17p) data in the total cohort (n = 1,220), 113 cases were TP53 mutated only (73/113 with low-VAF mutations), 55 del17p/TP53 mutated (3/55 with low-VAF mutations), 20 del17p only, and 1,032 (84.6%) TP53 wild-type. A model including low-VAF cases outperformed the canonical model, which considered only high-VAF cases (c-indices 0.643 vs. 0.603, P < 0.0001), and improved the prognostic risk stratification of CLL International Prognostic Index. Clinical results were confirmed in CIT-treated cases (n = 552) from the retrospective cohort, and the UK trials cohort. CONCLUSIONS: TP53 mutations affected OS regardless of VAF. This finding can be used to update the definition of TP53 mutated CLL for clinical purposes.

Single Diastereomers of the Clinical Anticancer ProTide Agents NUC-1031 and NUC-3373 Preferentially Target Cancer Stem Cells In Vitro.

A 3'-protected route toward the synthesis of the diastereomers of clinically active ProTides, NUC-1031 and NUC-3373, is described. The in vitro cytotoxic activities of the individual diastereomers were found to be similar to their diastereomeric mixtures. In the KG1a cell line, NUC-1031 and NUC-3373 have preferential cytotoxic effects on leukemic stem cells (LSCs). These effects were not diastereomer-specific and were not observed with the parental nucleoside analogues gemcitabine and FUDR, respectively. In addition, NUC-1031 preferentially targeted LSCs in primary AML samples and cancer stem cells in the prostate cancer cell line, LNCaP. Although the mechanism for this remains incompletely resolved, NUC-1031-treated cells showed increased levels of triphosphate in both LSC and bulk tumor fractions. As ProTides are not dependent on nucleoside transporters, it seems possible that the LSC targeting observed with ProTides may be caused, at least in part, by preferential accumulation of metabolized nucleos(t)ide analogues.

Structure-based design of highly selective 2,4,5-trisubstituted pyrimidine CDK9 inhibitors as anti-cancer agents.

Cyclin-dependent kinases (CDKs) are a family of Ser/Thr kinases involved in cell cycle and transcriptional regulation. CDK9 regulates transcriptional elongation and this unique property has made it a potential target for several diseases. Due to the conserved ATP binding site, designing selective CDK9 inhibitors has been challenging. Here we report our continued efforts in the optimization of 2,4,5-tri-substituted pyrimidine compounds as potent and selective CDK9 inhibitors. The most selective compound 30m was >100-fold selective for CDK9 over CDK1 and CDK2. These compounds showed broad anti-proliferative activities in various solid tumour cell lines and patient-derived chronic lymphocytic leukaemia (CLL) cells. Decreased phosphorylation of the carboxyl terminal domain (CTD) of RNAPII at Ser-2 and down-regulation of anti-apoptotic protein Mcl-1 were confirmed in both the ovarian cancer model A2780 and patient-derived CLL cells.

TLR9 expression in chronic lymphocytic leukemia identifies a promigratory subpopulation and novel therapeutic target.

Chronic lymphocytic leukemia (CLL) remains incurable despite B-cell receptor-targeted inhibitors revolutionizing treatment. This suggests that other signaling molecules are involved in disease escape mechanisms and resistance. Toll-like receptor 9 (TLR9) is a promising candidate that is activated by unmethylated cytosine guanine dinucleotide-DNA. Here, we show that plasma from patients with CLL contains significantly more unmethylated DNA than plasma from healthy control subjects (P < .0001) and that cell-free DNA levels correlate with the prognostic markers CD38, ß2-microglobulin, and lymphocyte doubling time. Furthermore, elevated cell-free DNA was associated with shorter time to first treatment (hazard ratio, 4.0; P = .003). We also show that TLR9 expression was associated with in vitro CLL cell migration (P < .001), and intracellular endosomal TLR9 strongly correlated with aberrant surface expression (sTLR9; r = 0.9). In addition, lymph node-derived CLL cells exhibited increased sTLR9 (P = .016), and RNA-sequencing of paired sTLR9hi and sTLR9lo CLL cells revealed differential transcription of genes involved in TLR signaling, adhesion, motility, and inflammation in sTLR9hi cells. Mechanistically, a TLR9 agonist, ODN2006, promoted CLL cell migration (P < .001) that was mediated by p65 NF-κB and STAT3 transcription factor activation. Importantly, autologous plasma induced the same effects, which were reversed by a TLR9 antagonist. Furthermore, high TLR9 expression promoted engraftment and rapid disease progression in a NOD/Shi-scid/IL-2Rγnull mouse xenograft model. Finally, we showed that dual targeting of TLR9 and Bruton's tyrosine kinase (BTK) was strongly synergistic (median combination index, 0.2 at half maximal effective dose), which highlights the distinct role for TLR9 signaling in CLL and the potential for combined targeting of TLR9 and BTK as a more effective treatment strategy in this incurable disease.

Managing drug-induced QT prolongation in clinical practice.

Many drug therapies are associated with prolongation of the QT interval. This may increase the risk of Torsades de Pointes (TdP), a potentially life-threatening cardiac arrhythmia. As the QT interval varies with a change in heart rate, various formulae can adjust for this, producing a 'corrected QT' (QTc) value. Normal QTc intervals are typically <450 ms for men and <460 ms for women. For every 10 ms increase, there is a ~5% increase in the risk of arrhythmic events. When prescribing drugs associated with QT prolongation, three key factors should be considered: patient-related risk factors (eg, female sex, age >65 years, uncorrected electrolyte disturbances); the potential risk and degree of QT prolongation associated with the proposed drug; and co-prescribed medicines that could increase the risk of QT prolongation. To support clinicians, who are likely to prescribe such medicines in their daily practice, we developed a simple algorithm to help guide clinical management in patients who are at risk of QT prolongation/TdP, those exposed to QT-prolonging medication or have QT prolongation.