Two-drug Combination Research Articles

Triple conjugated carbon dots as a nano-drug delivery model for glioblastoma brain tumors.

Most of the dual nano drug delivery systems fail to enter malignant brain tumors due to a lack of proper targeting systems and the size increase of the nanoparticles after drug conjugation. Therefore, a triple conjugated system was developed with carbon dots (C-dots), which have an average particle size of 1.5-1.7 nm. C-dots were conjugated with transferrin (the targeted ligand) and two anti-cancer drugs, epirubicin and temozolomide, to build the triple conjugated system in which the average particle size was increased only up to 3.5 nm. In vitro studies were performed with glioblastoma brain tumor cell lines SJGBM2, CHLA266, CHLA200 (pediatric) and U87 (adult). The efficacy of the triple conjugated system (dual drug conjugation along with transferrin) was compared to those of dual conjugated systems (single drug conjugation along with transferrin), non-transferrin C-dots-drugs, and free drug combinations. Transferrin conjugated samples displayed the lowest cell viability even at a lower concentration. Among the transferrin conjugated samples, the triple conjugated system (C-dots-trans-temo-epi (C-DT)) was more strongly cytotoxic to brain tumor cell lines than dual conjugated systems (C-dots-trans-temo (C-TT) and C-dots-trans-epi (C-ET)). C-DT increased the cytotoxicity to 86% in SJGBM2 at 0.01 μM while C-ET and C-TT reduced it only to 33 and 8%, respectively. Not only did triple conjugated C-DT increase the cytotoxicity, but also the two-drug combination in C-DT displayed a synergistic effect.

Pattern and appropriateness of antihypertensive prescriptions among hospitalized hypertensives in Nigeria

Introduction: Prescribers' compliance to relevant guidelines may be a reflection of the depth of thoroughness in therapy, awareness, and a pointer to pitfalls in reducing cardiovascular mortality. This study was aimed to study the pattern and appropriateness of antihypertensive prescriptions among hospitalized patients with hypertensive disorders in Nigeria. Materials and Methods: This was a retrospective study. All medical admissions over a 1-year from January 1 to December 31, 2013, were reviewed from three teaching hospitals across Nigeria. Two hundred and eighty-eight hospitalized hypertensive patients were identified with complete records. The pattern of drugs prescription and their compliance with the Joint National Commission VII criteria was determined. Results: The mean age was 57.6 ± 15.7 years. Associated comorbid conditions include heart failure, transient ischemic attack, and type 2 diabetes mellitus. Commonly prescribed drugs include angiotensin-converting enzyme inhibitors (ACE-I), diuretics, calcium channel blockers (CCBs), and angiotensin receptor blockers. The proportions of participants using these drugs were 57.3%, 34.0%, 26.4%, and 12.5%, respectively. Fifty-one (20.73%) were on a single medication, 108 (43.9%) were on two medication classes while 87 (35.37%) were on drugs from at least three classes of antihypertensive pharmacotherapy. Combination therapy is frequent among hospitalized hypertensive patients in this study. The common pattern of two-drug combination among study participants included ACE-I and diuretics. The most common three-drug combinations included ACE-I, CCBs, and diuretics. Conclusion: Majority of study participants were on combination therapy and had multiple comorbid cardiovascular risk factors, target organ damage, and complications. Antihypertensive prescriptions across three tertiary centers in Nigeria appear to follow relevant clinical guidelines with minimal differences across the centers.

Prescription Pattern of Antihypertensive Drugs: An Experience from a Secondary Care Hospital in the United Arab Emirates.

Objective:The aim of the study was to examine the prescription pattern of antihypertensive drugs used in a secondary care hospital in the United Arab Emirates (UAE).Methods:It was a prospective, observational study carried out in 588 adult hypertensive patients presenting to medicine outpatient and inpatient departments of Dibba Hospital, Fujairah, UAE. The study was conducted for a period of 6 months from December 2017 to May 2018. Demographic and clinical data were collected from electronic patient case records and documented. Prescriptions were studied overall for drug use details and for specific types of antihypertensive drugs. The World Health Organization Anatomical Therapeutic Chemical/Defined Daily Dose methodology was further used to calculate utilization. Statistical analysis of data was performed using Statistical Package for the Social Sciences 24.0.Findings:Of the 588 study participants, majority of the patients were on two-drug combination antihypertensive therapy (n = 210, 35.5%) followed by monotherapy (n = 188, 32.1%) and three-drug combination (n = 136, 23.1%). Calcium channel blockers were the most frequently (51%) prescribed class both in monotherapy and in combination therapy while angiotensin receptor blockers and angiotensin-converting enzyme inhibitors (55.9%) were the most preferred agents for monotherapy. Among individual antihypertensive drugs, amlodipine was prescribed the most (266 prescriptions), irrespective of monotherapy or combination therapy.Conclusion:Our study represents the current prescribing trends of antihypertensive drugs in a secondary care hospital in the UAE. The use of antihypertensive drugs largely conforms to international guidelines, but still, there is room for improvement in terms of rational drug utilization.

How to implement the new 2018 ESH/ESC guidelines for the management of arterial hypertension in patients with metabolic syndrome and diabetes?

Blood pressure (BP) control in hypertensive patients remains poor worldwide, particularly in high-risk patients with hypertension and diabetes. New ESH/ESC guidelines recommend more stringent BP targets (on-treatment values of ≤ 130/80 mm Hg in the general population and ≤ 140/90 mm Hg in older hypertensive people), which will make the achievement of BP control even more challenging. The most effective evidence-based treatment strategy to improve BP control is one that: encourages the use of combination treatment, enables the use of single-pill combination (SPC) therapy for most patients to improve adherence to treatment, with the use of SPC therapy as initial therapy. The combination of perindopril with thiazide-like diuretic indapamide is one of the widely tested SPC in multicentre clinical trials for diabetic patients. Studies suggested that two-drug combination therapy will control BP in approximately two-thirds of patients. For patients whose BP is not controlled by two-drug combination therapy, the logical option is to increase treatment to three-drug combination therapy: usually a RAS blocker, a CCB and a diuretic. The combination of perindopril with indapamide and amlodipine is particularly recommended in population of hypertensive patients with metabolic complications because of favourable, neutral effect on blood glucose and cholesterol level. This combination has proven hypotensive effect in group of patients with difficult-to-control hypertension.

Rhabdomyolysis risk from the use of two-drug combination of antidyslipidemic drugs with antihypertensive and antidiabetic medications: a signal detection analysis.

Rhabdomyolysis is one of the most concerning complications of antidyslipidemic drugs. Most patients with dyslipidemia take multiple medications. Our objective was to explore which two-drug combinations lead to a higher risk of rhabdomyolysis. We analyzed data from the Japanese Adverse Drug Event Report (JADER) database between April 2004 and September 2017. The primary outcome was the report of rhabdomyolysis. We assessed the risk of rhabdomyolysis for the two-drug concomitant use of antidyslipidemic drugs (statin, fibrate, and ezetimibe) with antihypertensive and antidiabetic medications. The Norén and Gosho methods were used for detecting two-drug interactions. The JADER contained 468292 records for patient characteristics, 2973172 drug information records, and 741016 adverse reactions records. Rhabdomyolysis was reported in 5017 patients. Concomitant use of pravastatin/fenofibrate, simvastatin/mefruside, fluvastatin/temocapril, bezafibrate/temocapril, bezafibrate/spironolactone, bezafibrate/metoprolol, bezafibrate/losartan, fluvastatin/mitiglinide, or fenofibrate/glibenclamide was detected as the signal of rhabdomyolysis in this analysis. Combination therapy with the drugs listed above has the potential of drug-drug interactions that could result in rhabdomyolysis in patients with dyslipidemia.

Pharmacodynamical Modeling of Two-Way Synergistic Effect for High-Throughput Drug Combination Screening in an Ex Vivo Reconstruction of Bone Marrow Using Primary Multiple Myeloma Cells

Introduction: Innate and acquired resistance to anti-cancer therapies poses a major hurdle in effectively treating many cancers, especially an incurable cancer like multiple myeloma (MM). Rational combination therapies have shown improved efficacy and reduced toxicity in MM. Patient variability in response to single agents leads to variability in combination effects, which require quantification on a patient-to-patient basis. Conventional combination effect quantification methods rely on dose - response curves obtained from experiments involving cell lines. Such studies don't account for intratumoral and intertumoral heterogeneity that play an important factor in driving a patient's clinical response.Materials and Methods: We propose a framework that captures tumor-specific two-way combination effect in an ex vivo reconstruction of the tumor microenvironment using patient-derived primary multiple myeloma cells. The framework translates the data obtained from an ex vivo drug sensitivity assay to patient-specific combination therapy response predictions using mathematical modeling. MM cells (CD138+) extracted from fresh bone marrow aspirates are seeded in an ex vivo co-culture model with human stroma in multi-well plates, and tested with various drugs/combinations at several concentrations. Each well is imaged for at least 96 hours, once every 30 minutes to estimate percent viable cells. Such a platform facilitates measuring response with respect to dose and time, making this an ideal paradigm to capture pharmacodynamical interactions between drugs. An empirical mathematical model is used to measure the combination effects between two drugs, and when combined with their pharmacokinetic data obtained from Phase-I clinical trials the model predicts patient-specific response over a 90 day treatment period within five days post biopsy.Results: A total of 58 multiple myeloma patient samples were tested ex vivo with 19 two-drug combinations. The resulting ex vivo response data is fit to single agent (EMMA - Ex vivo Mathematical Myeloma Advisor) and combination (SAM - Synergy Augmented Model) mathematical models to estimate patient-drug/combination-specific LD50s and area under the curves (AUCs) from the dose-time-response curves (shown in Figs. 1a-f). The 96 hour single agent, additive (in the sense of Bliss), and combination LD50s for 19 patients tested with the combination Carfilzomib and Dexamethasone (CFZ+DEX) are presented as a box plot in Fig. 2a . A red dashed line signifies a patient who would see a benefit over additive LD50 (synergism), while a blue dashed line implies the opposite (antagonism). Similarly, Fig. 2b presents the AUCs as a box plot, where the “area” in AUC is in fact the volume under the dose-time-response curve. Inclusion of the time axis accounts for exposure-response effect in addition to the dose-response effect captured in LD50. The effect of accounting for exposure via AUC suggests greater synergy than LD50 as seen in Figs. 2a-b. In spite of being insightful, a decrease in LD50 and/or AUC doesn't always translate to a synergistic effect in patients. In order to predict the response observed in patients, the ex vivo models are integrated with pharmacokinetic data from Phase-I clinical trials to simulate patients' response over a 90 day treatment period (shown in Figs. 1j-l). The best response over a 90 day period for the single agents, additive, and the combination are presented in Fig. 2c as a box plot and the right y-axis classifies the response. However, additive effect is a theoretically computed quantity that may have pharmacological relevance but isn't significant clinically. A more clinically relevant reference model would be to compare the combination response with the better of the two single agents. Figure 2d presents the box plot comparing the predicted best single agent and combination responses. The model predictions indicate all of the 19 patients would benefit from the combination, although the extent of benefit varies from patient-to-patient.Conclusion: The proposed framework captures patient-specific combination effects using a pharmacodynamic model that can be used to screen for the most efficacious combination for a patient and across a cohort. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Evaluation of bactericidal and anti-biofilm activities of silver nanoparticles against multidrug-resistant Gram-negative bacilli isolated from burn wound infections

Background: The emergence and spread of multidrug-resistant Gram-negative bacilliin burn wound infections related to biofilm formation, which lend to challenge in treatment with conventional antibiotics andprompting to search for novel antimicrobial agents to control the infections.Silver nanoparticles (AgNPs) have wide spectrum biological properties with different mechanisms of action and less toxicity towards human cells.
 Objective:The goal of this study was to evaluated the anti-bacterial and anti-biofilm activities of AgNPs alone and in combination with aminoglycoside (Amikacin) and β-lactam (Ampicillin) antibiotics against multidrug resistant Gram-negative bacilli (Pseudomonas aeruginosa, Escherichia coli, klebsiellapneumoniae) isolated from burn wound infections. Type of the study: Cross –sectional study.
 Methods: 70 clinical isolates of GNBtested for susceptibility tests by disk diffusion method against 10 antibiotics. The minimum inhibitory concentrations (MICs) of AgNPs and antibiotics were carried out according to the standard broth microdilution method, while synergistic interactions were evaluated by time kill-kinetic assays. Calgary method was applied for anti-biofilm activity.
 Results:Pseudomonas aeruginosa represented the majority of GNBisolated from burn wound infections 34 (48.5 %)followed by Klebsiella pneumonia 21 (30 %) and Escherichia coli 15 (21.5 %). Silver nanoparticles showed remarkable antibacterial activity against GNB that isolated from burn wound infections with the MICs between 25- 75 µg/ml. Aztreonam, amikacin and cefepime were the most effective antimicrobial drugagainst GNB isolates.Synergistic bactericidal effects were observed in two-drug combinations of AgNPswith broad-spectrum aminoglycoside (Amikacin) and β-lactam (Ampicillin) antibiotics against multidrug resistant GNB. In addition,AgNPsalone or in combination with ampicillin inhibited biofilm activity about 60 % – 75 % ofGNB,while combination of AgNPs withamikacin exhibited a powerful anti-biofilm activity and inhibition biofilm formation by 75% to 80%.
 Conclusion: The results confirmed a synergistic bactericidal effects and significant enhancing of anti-biofilm activity of AgNPs in combination with antibiotics (amikacin and ampicillin) against multidrug resistant GNB isolated from burn wound infections. These data suggest that AgNPs could beapplied as nanodrug for treatment of burn wound infections

Optimized Background Regimen for Treatment of Active Tuberculosis with the Next-Generation Benzothiazinone Macozinone (PBTZ169).

The efficacy of the standardized four-drug regimen (comprising isoniazid, rifampin, pyrazinamide, and ethambutol) for the treatment of tuberculosis (TB) is menaced by the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis Intensive efforts have been made to develop new antibiotics or to repurpose old drugs, and several of these are currently being evaluated in clinical trials for their antitubercular activity. Among the new candidate drugs is macozinone (MCZ), the piperazine-containing benzothiazinone PBTZ169, which is currently being evaluated in phase I/II clinical trials. Here, we determined the in vitro and in vivo activity of MCZ in combination with a range of anti-TB drugs in order to design a new regimen against active TB. Two-drug combinations with MCZ were tested against M. tuberculosis using checkerboard and CFU enumeration after drug exposure assays. MCZ was observed to have no interactions with all first- and second-line anti-TB drugs. At the MIC of each drug, MCZ with either bedaquiline (BDQ), clofazimine (CLO), delamanid (DMD), or sutezolid (STZ) reduced the bacterial burden by 2 logs compared to that achieved with the drugs alone, indicating synergism. MCZ also displayed synergism with clomiphene (CLM), a potential inhibitor of the undecaprenyl pyrophosphate synthase (UppS) in mycobacteria. For all the other drugs tested in combination with MCZ, no synergistic activity was observed. Neither antagonism nor increased cytotoxicity was found for most combinations, suggesting that MCZ could be added to different TB treatment regimens without any significant adverse effects.

Development of a Robust UPLC Method for Simultaneous Determination of a Novel Combination of Sofosbuvir and Daclatasvir in Human Plasma: Clinical Application to Therapeutic Drug Monitoring.

A rapid and selective UPLC-DAD method was developed and validated for simultaneous analysis of the novel two-drug combination Darvoni® for the treatment of HCV: Sofosbuvir (SF)/Daclatasvir (DC) in human plasma using Ledipasvir as internal standard (IS) where the extraction process was conducted using automated SPE. Although the analysis of the combination after concomitant oral intake of two tablets of SF and DC individually was reported in literature, yet simultaneous analysis of this new combination in human plasma after a single oral dose was not previously reported. The adopted chromatographic separation was achieved on Waters® Acquity UPLC BEH C18 column (2.1 × 50 mm, 1.7 µm) as a stationary phase using isocratic elution using a mobile phase system of ammonium formate (pH 3.5; 5 mM) and acetonitrile (60:40 v/v) pumped at a flow rate of 0.2 mL.min−1. The UV detection was carried out at 261 nm for SF and 318 nm for DC and IS. SF was eluted at 1.123 min while DC was eluted at 3.179 min. The proposed chromatographic method was validated in accordance with guidelines of FDA for bioanalytical method validation. A linear range was achieved in the range of 25-6400 and 50-12800 ng.mL−1 for SF and DC, respectively. The proposed UPLC-DAD method was found to be accurate with % bias ranging between -10.0-7.2 for SF and -6.9-8.0 for DC. Also it was proved to be precise with % CV for intraday precision ranging between 3.8-9.6 for SF and 2.8-9.2 for DC whereas interday precision ranged between 5.1-9.3 for SF and 3.7-9.1 for DC. Moreover, % extraction recovery ranged between 90.0-107.2 for SF and 93.1-108.0 for DC using the suggested method. The adopted chromatographic method was successfully applied to the therapeutic drug monitoring of SF and DC in healthy volunteers after the oral intake of one Darvoni® tablet.

Breast Cancer Chemo-immunotherapy through Liposomal Delivery of an Immunogenic Cell Death Stimulus Plus Interference in the IDO-1 Pathway.

Immunotherapy provides the best approach to reduce the high mortality of metastatic breast cancer (BC). We demonstrate a chemo-immunotherapy approach, which utilizes a liposomal carrier to simultaneously trigger immunogenic cell death (ICD) as well as interfere in the regionally overexpressed immunosuppressive effect of indoleamine 2,3-dioxygenase (IDO-1) at the BC tumor site. The liposome was constructed by self-assembly of a phospholipid-conjugated prodrug, indoximod (IND), which inhibits the IDO-1 pathway, followed by the remote loading of the ICD-inducing chemo drug, doxorubicin (DOX). Intravenous injection of the encapsulated two-drug combination dramatically improved the pharmacokinetics and tumor drug concentrations of DOX and IND in an orthotopic 4T1 tumor model in syngeneic mice. Delivery of a threshold ICD stimulus resulted in the uptake of dying BC cells by dendritic cells, tumor antigen presentation and the activation/recruitment of naïve T-cells. The subsequent activation of perforin- and IFN-γ releasing cytotoxic T-cells induced robust tumor cell killing at the primary as well as metastatic tumor sites. Immune phenotyping of the tumor tissues confirmed the recruitment of CD8+ cytotoxic T lymphocytes (CTLs), disappearance of Tregs, and an increase in CD8+/FOXP3+ T-cell ratios. Not only does the DOX/IND-Liposome provide a synergistic antitumor response that is superior to a DOX-only liposome, but it also demonstrated that the carrier could be effectively combined with PD-1 blocking antibodies to eradicate lung metastases. All considered, an innovative nano-enabled approach has been established to allow deliberate use of ICD to switch an immune deplete to an immune replete BC microenvironment, allowing further boosting of the response by coadministered IDO inhibitors or immune checkpoint blocking antibodies.

Synergistic and bactericidal activities of mecillinam, amoxicillin and clavulanic acid combinations against extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in 24-h time–kill experiments

This study aimed to evaluate the potential synergistic and bactericidal effects of mecillinam in combination with amoxicillin and clavulanic acid against extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. Eight clinical E. coli isolates with varying susceptibility to mecillinam [minimum inhibitory concentrations (MICs) of 0.125 mg/L to >256 mg/L] and high-level resistance to amoxicillin (MICs > 256 mg/L) were used. Whole-genome sequencing was performed to determine the presence of β-lactamase genes and mutations in the cysB gene. The activities of single drugs and the combinations of two or three drugs were tested in 24-h time-kill experiments. Population analysis was performed for two strains before and after experiments. Only one strain had a mutation in the cysB gene resulting in an amino acid substitution. With the two-drug combinations, initial killing was observed both with mecillinam and amoxicillin when combined with clavulanic acid. Synergy was observed with mecillinam and clavulanic acid against one strain and with amoxicillin and clavulanic acid against three strains. However, following significant re-growth, a bactericidal effect was found only with amoxicillin and clavulanic acid against two strains. Pre-existing subpopulations with elevated mecillinam MICs were detected before experiments and were selected with mecillinam alone or in two-drug combinations. In contrast, the three-drug combination showed enhanced activity with synergy against six strains, a bactericidal effect against all eight strains, and suppression of resistance during 24-h antibiotic exposure. This combination may be of clinical interest in the treatment of urinary tract infections caused by ESBL-producing E. coli.

Modulation of multidrug resistant in cancer cells by EGCG, tannic acid and curcumin

Background: Cancer is one of the most common life-threatening diseases worldwide; many patients develop multidrug resistance after treatment with anticancer drugs. The main mechanism leading to multidrug resistance is the overexpression of ABC transporters in cancer cells. Chemosensitizers are needed to inhibit the activity of ABC transporters, resulting in higer intracellular concentration of anticancer drugs. Some secondary metabolites have been reported to be chemosensitizers by inhibiting ABC transporters. Epigallocatechin gallate (EGCG), tannic acid, and curcumin were employed in this study. Different assays were used to detect whether they have the ability to inhibit P-gp activity and overcome multidrug resistance in cancer cells overexpressing P-gp. Hypothesis/Purpose: CEM/ADR 5000 and Caco-2 cell lines, which overexpress P-gp, are multidrug resistant cell lines. We first detected whether the combination of polyphenols (EGCG, tannic acid, curcumin) and doxorubicin, an anticancer drug, is synergistic or not. To further understand the potential mechanism, EGCG, tannic acid, and curcumin were tested to check whether they have the ability to inhibit P-gp activity. When P-gp activity is inhibited, the intracellular concentration of doxorubicin is higher, resulting in enhanced cytotoxicity of doxorubicin. Study design: The P-gp overexpressing human colon cancer cell line Caco-2 and human T-lymphoblastic leukemia cell line CEM/ADR 5000 were used in this study. Two-drug combinations (doxorubicin + polyphenol) and three-drug combinations (doxorubicin + polyphenol + digitonin) were tested to examine potential synergism. The potential mechanism leading to synergism would be the inhibition of P-gp activity. A Rhodamine 123 assay and Calcein-AM assay in Caco-2 and CEM/ADR 5000, respectively, were used to detect P-gp inhibition by EGCG, curcumin, and tannic acid. Methods: MTT assay was used to determine the cytotoxicity of doxorubicin, polyphenols and digitonin alone, and then their combinations. Furthermore, Rhodamine 123 and Calcein-AM were used to detect the effects of polyphenols on the activity of P-gp. Results: The results demonstrated that a combination of non-toxic concentrations of each polyphenol with doxorubicin synergistically sensitized Caco-2 and CEM/ADR 5000 cells. Furthermore, three-drug combinations (doxorubicin + polyphenol + digitonin) were much more effective. In addition, the activity of P-gp in Caco-2 and CEM/ADR 5000 cells was measured. Consistent with the combination results, tannic acid and curcumin decreased the activity of P-gp both in Caco-2 and CEM/ADR 5000. EGCG, which weakly affected the activity of P-gp in CEM/ADR 5000, only had an effect on P-gp under higher concentration in Caco-2 cells. Conclusion: Our results show that EGCG, curcumin, and tannic acid, when combined with doxorubicin, can exert synergism, mediated by a reduced activity of P-gp. This study suggests that polyphenols, by modulating the activity of P-gp, may be used as chemosensitisers.

Prevalence and patterns of higher-order drug interactions in Escherichia coli

Interactions and emergent processes are essential for research on complex systems involving many components. Most studies focus solely on pairwise interactions and ignore higher-order interactions among three or more components. To gain deeper insights into higher-order interactions and complex environments, we study antibiotic combinations applied to pathogenic Escherichia coli and obtain unprecedented amounts of detailed data (251 two-drug combinations, 1512 three-drug combinations, 5670 four-drug combinations, and 13608 five-drug combinations). Directly opposite to previous assumptions and reports, we find higher-order interactions increase in frequency with the number of drugs in the bacteria’s environment. Specifically, as more drugs are added, we observe an elevated frequency of net synergy (effect greater than expected based on independent individual effects) and also increased instances of emergent antagonism (effect less than expected based on lower-order interaction effects). These findings have implications for the potential efficacy of drug combinations and are crucial for better navigating problems associated with the combinatorial complexity of multi-component systems.

Early cardiovascular protection by initial two-drug fixed-dose combination treatment vs. monotherapy in hypertension.

Guidelines support use of drug combinations in most hypertensive patients, and recently treatment initiation with two drugs has been also recommended. However, limited evidence is available on whether this leads to greater cardiovascular (CV) protection compared to initial monotherapy. Using the healthcare utilization database of the Lombardy Region (Italy), the 44534 residents of the region (age 40-80 years) who in 2010 started treatment with one antihypertensive drug (n = 37078) or a two-drug fixed-dose combination (FDC, n = 7456) were followed for 1 year after treatment initiation to compare the risk of hospitalization for CV disease associated with the two treatment strategies. To limit the confounding associated with non-randomized between-group comparisons, data were also analysed by: (i) matching the two groups by the high-dimensional propensity score (HDPS) and (ii) comparing, in patients experiencing one or more CV events (n = 2212), the CV event incidence during subperiods in which patients were prescribed mono- or FDC therapy (self-controlled case series design). Compared to initial monotherapy, patients on initial FDC therapy showed a reduced 1 year risk of hospitalization for any CV event (-21%, P < 0.01). This was the case also when groups were compared according to the HDPS analysis (-15%, P < 0.05). Finally, in patients experiencing CV events, the event incidence was much less when, during the 1 year follow-up, they were under FDC therapy than under monotherapy (-56%, P < 0.01). The reduced risk of hospitalization was always significant for ischaemic heart disease and new onset atrial fibrillation, and included hospitalization for cerebrovascular disease and heart failure when monotherapy and FDC therapy were compared within patients. In a real-life setting, a comparison of the incidence of early CV events during antihypertensive monotherapy and FDC shows that the latter strategy leads to a more effective CV protection. This scores in favour of a two-drug FDC strategy as first step in the hypertensive population.

Dolutegravir-rilpivirine coformulation.

With prolonged life expectancy in HIV-positive patients on combination antiretroviral therapy, the quest for reducing lifelong drug exposure and minimizing or avoiding the toxicities of combination antiretroviral therapy while maintaining viral suppression has emerged when coformulations of antiretroviral agents with improved convenience, and better tolerability and efficacy became available. This review aims to update the current experience with the novel two-drug combination of dolutegravir (DTG) and rilpivirine (RPV) and elucidate the possible applications and limitations of coformulated DTG-RPV in the future. Five observational studies and two randomized, noninferiority trials (SWORD-1 and SWORD-2) evaluated the use of DTG and RPV in treatment-experienced patients. Despite variable inclusion criteria, 95-100% of the included patients maintained plasma HIV RNA load less than 50 copies/ml at the end of 24-48 weeks of observation. Overall, this regimen was well tolerated and only 0.8-7.9% of the patients discontinued the regimen due to adverse events. DTG and RPV is a novel two-drug antiretroviral combination regimen that can be effectively and safely used in patients with viral suppression for 6 months or longer. However, its use in patients with a previous history of virological failure and/or antiretroviral resistance warrants further investigation.

Abstract 1185: Synergistic drug combinations promote expansion of partially-resistant subpopulations in computational modeling of cancer heterogeneity and graded plasticity

Abstract Introduction: Synergistic drug combinations are widely sought as anti-cancer strategies because they yield higher therapeutic efficacy than additive or antagonistic combinations, enabling reduced doses. The effect of synergistic drugs (versus non-synergistic drugs) on the process of drug resistance evolution is not well understood, particularly for heterogeneous cell populations and for gradual phenotype transitions toward resistance. In this work, we use computational modeling of cancer cell numbers to interrogate the dynamics of resistance evolution during treatment with two-drug combinations. Methods: We developed computational models of cancer evolution under two-drug combination therapy, to study the development of drug resistance in cancers with varying heterogeneity or graded plasticity of resistance. A large population of cells was simulated to undergo infrequent but stochastic phenotype change over time, subject to a pharmacological dosing model of combination effects. Results: When synergistic and non-synergistic combinations were administered at equally effective doses in silico, drug resistance evolved more rapidly under the synergistic drugs. When we modeled graded plasticity by simulating multiple levels of drug resistance, results were similar except with additional bottlenecks before fully resistant cells could emerge. Meanwhile, as heterogeneity increased, synergism increased the speed of forming resistant subclones with higher fitness. Because synergistic treatments by nature exploit the simultaneous action of both drugs for their efficacy, the development of partial or single-drug resistance caused a disproportionate escape from drug effects and faster clonal expansion under synergistic therapy, compared with additive or non-synergistic therapies. Our simulations consistently showed that pairs of drugs with less synergism were able to prolong the time until double-resistance arose, provided the comparison combinations were dosed for equal initial efficacy. Conclusion: We identify dosing criteria whereby synergistic pairs of drugs actually have worse performance than additive or non-synergistic pairs, for delaying the onset of double-drug resistance. Dosing criteria are also shown for graded resistance and variable levels of population heterogeneity. Future work must examine non-heritable contributions to resistance, such as micro-environmental effects. Our theoretical work shows the need for further study of the divergence between short-term and long-term drug efficacy in the presence of clonal selection, and suggests increased attention to non-synergistic drug combinations as therapeutic candidates. Citation Format: Elysia C. Saputra, Lu Huang, Lisa Tucker-Kellogg. Synergistic drug combinations promote expansion of partially-resistant subpopulations in computational modeling of cancer heterogeneity and graded plasticity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1185.

Synergistic Effects of Resveratrol and Pyrimethanil against Botrytis cinerea on Grape.

Botrytis cinerea is the pathogen of gray mold disease affecting a wide range of plant hosts, with consequential economic losses worldwide. The increased frequency of fungicide resistance of the pathogen challenges its disease management, and thus the development of alternative control strategies are urgently required. In this study, we showed excellent synergistic interactions between resveratrol and pyrimethanil. Significant synergistic values were recorded by the two-drug combination on the suppression of mycelial growth and conidia germination of B. cinerea. The combination of resveratrol and pyrimethanil caused malformation of mycelia. Moreover, the inoculation assay was conducted on table grape and consistent synergistic suppression of the two-drug combination was found in vivo. Our findings first revealed that the combination of resveratrol and pyrimethanil has synergistic effects against resistant B. cinerea and support the potential use of resveratrol as a promising adjuvant on the control of gray mold.

PO-023 A multi-step framework to analyse high-throughput drug combination screens

Introduction Tailored, genotype-driven therapies are the future for treatment of heterogeneous cancers like breast cancer. However, despite their high therapeutic index, targeted agents often have limited success in single agent treatment setups due to variable clinical response rates and resistance. Thus, a framework to develop drug combinations for treatment of cancer is needed. Material and methods Our group has an ongoing effort to systematically screen two-drug combinations in cancer type-specific and pan-cancer high-throughput drug combination screens. We have screened over 1000 combinations, including both broad-acting chemotherapeutics and targeted compounds. Cancer type-specific drug combination screens were conducted in breast and colorectal cancer cell lines, using a panel of 50 cell lines in each screen. Acquired data has been used to determine a strategy to extract the most promising drug combinations in each tissue. Results and discussions We propose a multi-step analytical framework for the identification and prioritisation of synergistic combinations. Initial filtering is based on several parameters, including synergy (z-score), XMID and Emax. Robustness of drug response effects is assessed through rescreening of selected drug combinations. Further prioritisation of promising combinations in a tissue-specific setting is achieved through stratification of the combination drug response in cell line subgroups, including segregation based on commonly mutated genes and molecular subtypes (e.g. PAM50 subgrouping in breast cancer). Moreover, systematic exploration of genotype-drug synergy associations will be used to identify biomarkers of response for patient stratification. Conclusion In conclusion, we have developed a multi-step framework to identify clinically relevant synergistic drug combinations complementing current cancer therapy options. This pipeline may facilitate future combination drug synergy predictions and validation.

Drugs in Development for Malaria.

The last two decades have seen a surge in antimalarial drug development with product development partnerships taking a leading role. Resistance of Plasmodium falciparum to the artemisinin derivatives, piperaquine and mefloquine in Southeast Asia means new antimalarials are needed with some urgency. There are at least 13 agents in clinical development. Most of these are blood schizonticides for the treatment of uncomplicated falciparum malaria, under evaluation either singly or as part of two-drug combinations. Leading candidates progressing through the pipeline are artefenomel–ferroquine and lumefantrine-KAF156, both in Phase 2b. Treatment of severe malaria continues to rely on two parenteral drugs with ancient forebears: artesunate and quinine, with sevuparin being evaluated as an adjuvant therapy. Tafenoquine is under review by stringent regulatory authorities for approval as a single-dose treatment for Plasmodium vivax relapse prevention. This represents an advance over standard 14-day primaquine regimens; however, the risk of acute haemolytic anaemia in patients with glucose-6-phosphate dehydrogenase deficiency remains. For disease prevention, several of the newer agents show potential but are unlikely to be recommended for use in the main target groups of pregnant women and young children for some years. Latest predictions are that the malaria burden will continue to be high in the coming decades. This fact, coupled with the repeated loss of antimalarials to resistance, indicates that new antimalarials will be needed for years to come. Failure of the artemisinin-based combinations in Southeast Asia has stimulated a reappraisal of current approaches to combination therapy for malaria with incorporation of three or more drugs in a single treatment under consideration.

Teicoplanin - Tigecycline Combination Shows Synergy Against Mycobacterium abscessus.

Lung disease caused by non-tuberculous mycobacteria (NTM), relatives of Mycobacterium tuberculosis, is increasing. M. abscessus is the most prevalent rapid growing NTM. This environmental pathogen is intrinsically resistant to most commonly used antibiotics, including anti-tuberculosis drugs. Current therapies take years to achieve cure, if cure if achieved. Thus, there is an urgent medical need to identify new, more efficacious treatments. Here, we explore the possibility of repurposing antibiotics developed for other indications. We asked whether novel two-drug combinations of clinically used antibiotics can be identified that show synergistic activity against this mycobacterium. An in vitro checkerboard titration assay was employed to test 180 dual combinations of 41 drugs against the clinical isolate M. abscessus Bamboo. The most attractive novel combination was further profiled against reference strains representing three sub-species (M. abscessus subsp. abscessus, massiliense and bolletii) and a collection of clinical isolates. This resulted in the identification of a novel synergistic antibiotic pair active against the M. abscessus complex: the glycopeptide teicoplanin with the glycylcycline tigecycline showed inhibitory activity at 2–3 μM (teicoplanin) and 1–2 μM (tigecycline). This novel combination can now be tested in M. abscessus animal models of infection and/or patients.