Polymorphisms in the multiple drug resistance protein 1 and in P-glycoprotein 1 are associated with time to event outcomes in patients with advanced multiple myeloma treated with bortezomib and pegylated liposomal doxorubicin

Single nucleotide polymorphisms (SNPs) in the multiple drug resistance protein 1 (MRP1) and P-glycoprotein 1 (MDR1) genes modulate their ability to mediate drug resistance. We therefore sought to retrospectively evaluate their influence on outcomes in relapsed and/or refractory myeloma patients treated with bortezomib or bortezomib with pegylated liposomal doxorubicin (PLD). The MRP1/R723Q polymorphism was found in five subjects among the 279 patient study population, all of whom received PLD + bortezomib. Its presence was associated with a longer time to progression (TTP; median 330 vs. 129 days; p = 0.0008), progression-free survival (PFS; median 338 vs. 129 days; p = 0.0006), and overall survival (p = 0.0045). MDR1/3435(C > T), which was in Hardy–Weinberg equilibrium, showed a trend of association with PFS (p = 0.0578), response rate (p = 0.0782) and TTP (p = 0.0923) in PLD + bortezomib patients, though no correlation was found in the bortezomib arm. In a recessive genetic model, MDR1/3435 T was significantly associated with a better TTP (p = 0.0405) and PFS (p = 0.0186) in PLD + bortezomib patients. These findings suggest a potential role for MRP1 and MDR1 SNPs in modulating the long-term outcome of relapsed and/or refractory myeloma patients treated with PLD + bortezomib. Moreover, they support prospective studies to determine if such data could be used to tailor therapy to the genetic makeup of individual patients

The interactions of age, genetics, and disease severity on tacrolimus dosing requirements after pediatric kidney and liver transplantation

Purpose: In children, data on the combined impact of age, genotype, and disease severity on tacrolimus (TAC) disposition are scarce. The aim of this study was to evaluate the effect of these covariates on tacrolimus dose requirements in the immediate post-transplant period in pediatric kidney and liver recipients. Methods: Data were retrospectively collected describing tacrolimus disposition, age, CYP3A5 and ABCB1 genotype, and pediatric risk of mortality (PRISM) scores for up to 14 days post-transplant in children receiving liver and renal transplants. Initial TAC dosing was equal in all patients and adjusted using therapeutic drug monitoring. We determined the relationship between covariates and tacrolimus disposition. Results: Forty-eight kidney and 42 liver transplant recipients (median ages 11.5 and 1.5 years, ranges 1.5-17.7 and 0.05-14.8 years, respectively) received TAC post-transplant. In both transplant groups, younger children (<5 years) needed higher TAC doses than older children [kidney: 0.15 (0.07-0.35) vs. 0.09 (0.02-0.20) mg/kg/12h, p = 0.046, liver: 0.12 (0.04-0.32) vs. 0.09 (0.01-0.18) mg/kg/12h, p

Photochemical internalisation of chemotherapy potentiates killing of multidrug-resistant breast and bladder cancer cells

Multidrug resistance (MDR) is the major confounding factor in adjuvant solid tumour chemotherapy. Increasing intracellular amounts of chemotherapeutics to circumvent MDR may be achieved by a novel delivery method, photochemical internalisation (PCI). PCI consists of the co-administration of drug and photosensitiser; upon light activation the latter induces intracellular release of organelle-bound drug. We investigated whether co-administration of hypericin (photosensitiser) with mitoxantrone (MTZ, chemotherapeutic) plus illumination potentiates cytotoxicity in MDR cancer cells. We mapped the extent of intracellular co-localisation of drug/photosensitiser. We determined whether PCI altered drug-excreting efflux pump P-glycoprotein (Pgp) expression or function in MDR cells. Bladder and breast cancer cells and their Pgp-overexpressing MDR subclones (MGHU1, MGHU1/R, MCF-7, MCF-7/R) were given hypericin/MTZ combinations, with/without blue-light illumination. Pilot experiments determined appropriate sublethal doses for each. Viability was determined by the 3-[4,5-dimethylthiazolyl]-2,5-diphenyltetrazolium bromide assay. Intracellular localisation was mapped by confocal microscopy. Pgp expression was detected by immunofluorescence and Pgp function investigated by Rhodamine123 efflux on confocal microscopy. MTZ alone (0.1–0.2 μg ml−1) killed up to 89% of drug-sensitive cells; MDR cells exhibited less cytotoxicity (6–28%). Hypericin (0.1–0.2 μM) effects were similar for all cells; light illumination caused none or minimal toxicity. In combination, MTZ /hypericin plus illumination, potentiated MDR cell killing, vs hypericin or MTZ alone. (MGHU1/R: 38.65 and 36.63% increase, P<0.05; MCF-7/R: 80.2 and 46.1% increase, P<0.001). Illumination of combined MTZ/hypericin increased killing by 28.15% (P<0.05 MGHU1/R) compared to dark controls. Intracytoplasmic vesicular co-localisation of MTZ/hypericin was evident before illumination and at serial times post-illumination. MTZ was always found in sensitive cell nuclei, but not in dark resistant cell nuclei. In illuminated resistant cells there was some mobilisation of MTZ into the nucleus. Pgp expression remained unchanged, regardless of drug exposure. Pgp efflux was blocked by the Pgp inhibitor verapamil (positive control) but not impeded by hypericin. The increased killing of MDR cancer cells demonstrated is consistent with PCI. PCI is a promising technique for enhancing treatment efficacy

Management of intra-abdominal infections : recommendations by the WSES 2016 consensus conference

This paper reports on the consensus conference on the management of intra-abdominal infections (IAIs) which was held on July 23, 2016, in Dublin, Ireland, as a part of the annual World Society of Emergency Surgery (WSES) meeting. This document covers all aspects of the management of IAIs. The Grading of Recommendations Assessment, Development and Evaluation recommendation is used, and this document represents the executive summary of the consensus conference findings.Peer reviewe

Searching for polymorphisms that affect gene expression and mRNA processing: Example ABCB1 (MDR1)

Cis-acting genetic variations can affect the amount and structure of mRNA/protein. Genomic surveys indicate that polymorphisms affecting transcription and mRNA processing, including splicing and turnover, may account for main share of genetic factors in human phenotypic variability; however, most of these polymorphisms remain yet to be discovered. We use allelic expression imbalance (AEI) as a quantitative phenotype in the search for functionalcis-acting polymorphisms in many genes includingABCB1 (multidrug resistance 1 gene, MDR1, Pgp). Previous studies have shown that ABCB1 activity correlates with a synonymous polymorphism. C3435T; however, the functional polymorphism and molecular mechanisms underlying this clinical association remained unknown. Analysis of allele-specific expression in liver autopsy samples and in vitro expression experiments showed that C3435T represents a main functional polymorphism, accounting for 1.5-to 2-fold changes in mRNA levels. The mechanism appears to involve increased mRNA turnover, probably as a result of different folding structures calculated for mRNA with the Mfold program. Other examples of the successful application of AEI analysis for studying functional polymorphism include5-HTT (serotonin transporter, SLC6A4) andOPRM1 (μ opioid receptor). AEI is therefore a powerful approach for detectingcis-acting polymorphisms affecting gene expression and mRNA processing