XRCC1-mediated DNA repair is associated with progression-free survival of multiple myeloma patients after autologous stem cell transplant.

Autologous stem cell transplant (ASCT) with high-dose melphalan (HDM) is the standard treatment for fit multiple myeloma (MM) patients. It is generally believed that some DNA repair proteins impact the activity to repair melphalan-induced DNA damage, thus potentially contributing to the patient's clinical response. However, knowledge of these proteins is limited. In the current study, we investigated the roles of XRCC1, a protein involved in base excision repair and single-strand break repair, in melphalan response in MM cells. Small interfering RNA knockdown of XRCC1 significantly increased the accumulation of melphalan-induced DNA damage in MM cells and sensitized them to melphalan treatment, indicating that genetic variation in XRCC1 may impact response to melphalan treatment. We then evaluated the association between an XRCC1 variant with reduced activity, rs25487 (R399Q), and clinical outcomes of 108 MM patients with melphalan therapy. Our results showed that XRCC1 rs25487 was associated with prolonged progression-free survival (PFS) in MM patients. The adjusted hazard ratio for PFS between patients carrying rs25487 AA/AG and GG was 0.42 (95% confidence interval: 0.25, 0.84, P = .014). Taken together, these results indicate that XRCC1 is involved in the repair of melphalan-induced DNA damage and XRCC1 rs25487 variant with impaired DNA repair function influences the clinical responses of HDM in MM patients.

Polymorphism in ANRIL is associated with relapse in patients with multiple myeloma after autologous stem cell transplant.

Multiple myeloma (MM) is a hematologic malignancy characterized by clonal proliferation of plasma cells and overproduction of monoclonal immunoglobins. Treatment with melphalan is currently standard of care for younger and fit patients when followed by hematopoietic stem cell transplantation (HSCT), and in transplant ineligible patients when used in combination regimens. It has been previously shown that changes in the p53 pathway are associated with melphalan efficacy, but the regulatory role of the p14ARF-MDM2-p53 axis has yet to be fully explored. Recently, a non-coding RNA, ANRIL (antisense non-coding RNA in the INK4-ARF locus) has been shown to negatively regulate the transcription of the entire INK4-ARF locus and simultaneously modulate the p53 and pRb pathways. Moreover, some single nucleotide polymorphisms (SNPs) in ANRIL have previously been associated with susceptibility to several malignancies. Here we investigated select ANRIL SNPs in DNA from patient-derived peripheral blood mononuclear cells obtained from 108 MM patients treated with high-dose melphalan followed by HSCT. Our results show that the rs2151280 (CàT) SNP in ANRIL was associated with worse progression-free survival (TC/CC vs TT: HR = 0.53, 95%CI, [0.26, 1.07], P = 0.07; adjusted HR = 0.39, 95%CI, [0.18, 0.84], P = 0.016), and the TT variant had higher ANRIL expression and lower p15, p14ARF, and p16 expression compared to the TC/CC variants. Our results indicate that ANRIL may be involved in melphalan-mediated apoptosis via down-regulating p14ARF and subsequent p53, and that the rs2151280 polymorphism may be a potential prognostic biomarker for relapse in melphalan-treated MM patients.

Evaluating the Impacts of CYP3A4*1B and CYP3A5*3 Variations on Pharmacokinetic Behavior and Clinical Outcomes in Multiple Myeloma Patients With Autologous Stem Cell Transplant.

BACKGROUND/AIM: There exists considerably large interpatient variability in pharmacokinetic exposure of high dose melphalan in multiple myeloma patients with hematopoietic stem-cell transplantation. In this study, we aimed to evaluate the potential impacts of CYP3A4*1B (rs2940574) and CYP3A5*3 (rs776746) variations on pharmacokinetic properties of melphalan and clinical outcomes in multiple myeloma (MM) patients. PATIENTS AND METHODS: Genotypes of CYP3A4*1B (rs2940574) and CYP3A5*3 (rs776746) were determined by validated gene-specific real-time PCR (RT-PCR) assays using DNA samples from 108 MM patients; plasma concentrations of melphalan at different time points were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: CYP3A4*1B/*1B and CYP3A5*3/*3 carriers appeared to have a short median progression-free survival time and a higher maximum melphalan plasma concentration than non-carriers [792 vs. over 950 days, p=0.08; 9.91 (2.67, 34.03) vs. 8.66 (4.46, 17.61) mg/l, p=0.039]. CONCLUSION: CYP3A4*1B/*1B and CYP3A5*3/*3 variations might influence melphalan therapy in MM patients through yet-to-be-identified mechanisms.

Methotrexate Disposition, Anti-Folate Activity, and Metabolomic Profiling to Identify Molecular Markers of Disease Activity and Drug Response in the Collagen-Induced Arthritis Mouse Model.

Methotrexate (MTX) is widely used in the treatment of autoimmune arthritis but is limited by its unpredictable and variable response profile. Currently, no biomarkers exist to predict or monitor early therapeutic responses to MTX. Using a collagen-induced arthritis (CIA) mouse model, this study aimed to identify biochemical pathways and biomarkers associated with MTX efficacy in autoimmune arthritis. Following arthritis disease induction, DBA/1J mice were treated with subcutaneous MTX (20 mg/kg/week) and disease activity was assessed based on disease activity scores (DAS) and paw volume (PV) measurements. Red blood cell (RBC) and plasma samples were collected at the end of the study and were assessed for folate and MTX content. Plasma samples were analyzed by semitargeted global metabolomic profiling and analyzed by univariate and multivariate analysis. Treatment with MTX was associated with significant reductions in disease activity based on both DAS (p = 0.0006) and PV (p = 0.0006). MTX therapy resulted in significant reductions in 5-methyltetrahydrofolate (5mTHF) levels in plasma (p = 0.02) and RBCs (p = 0.001). Reductions in both RBC and plasma 5mTHF were associated with lower DAS (p = 0.0007, p = 0.01, respectively) and PV (p = 0.001, p = 0.005, respectively). Increases in RBC MTX were associated with lower DAS (p = 0.003) but not PV (p = 0.23). Metabolomic analysis identified N-methylisoleucine (NMI) and quinolone as metabolites significantly altered in disease mice, which were corrected towards healthy control levels in mice treated with MTX. Reductions in plasma NMI were associated with lower DAS (p = 0.0002) and PV (p = 9.5 × 10-6). Increases in plasma quinolone were associated with lower DAS (p = 0.02) and PV (p = 0.01). Receiver-operating characteristic curve analysis identified plasma NMI (AUC = 1.00, p = 2.4 × 10-8), RBC 5mTHF (AUC = 0.99, p = 2.4 × 10-5), and plasma quinolone (AUC = 0.89, p = 0.01) as top discriminating metabolites of MTX treatment. Our data support a relationship between MTX efficacy and its effect on circulating folates and identified 5mTHF, NMI, and quinolone as potential therapeutic biomarkers of disease activity and MTX response in the CIA mouse model of autoimmune arthritis.

Factors associated with reduced infliximab exposure in the treatment of pediatric autoimmune disorders: a cross-sectional prospective convenience sampling study.

BACKGROUND: Inadequate systemic exposure to infliximab (IFX) is associated with treatment failure. This work evaluated factors associated with reduced IFX exposure in children with autoimmune disorders requiring IFX therapy. METHODS: In this single-center cross-sectional prospective study IFX trough concentrations and anti-drug antibodies (ADAs) were measured in serum from children diagnosed with inflammatory bowel disease (IBD) (n = 73), juvenile idiopathic arthritis (JIA) (n = 16), or uveitis (n = 8) receiving maintenance IFX infusions at an outpatient infusion clinic in a tertiary academic pediatric hospital. IFX concentrations in combination with population pharmacokinetic modeling were used to estimate IFX clearance. Patient demographic and clinical data were collected by chart review and evaluated for their relationship with IFX clearance. RESULTS: IFX trough concentrations ranged from 0 to > 40 µg/mL and were 3-fold lower in children with IBD compared to children with JIA (p = 0.0002) or uveitis (p = 0.001). Children with IBD were found to receive lower IFX doses with longer dosing intervals, resulting in dose intensities (mg/kg/day) that were 2-fold lower compared to children with JIA (p = 0.0002) or uveitis (p = 0.02). Use of population pharmacokinetic analysis to normalize for variation in dosing practices demonstrated that increased IFX clearance was associated with ADA positivity (p = 0.004), male gender (p = 0.02), elevated erythrocyte sedimentation rate (ESR) (p = 0.02), elevated c-reactive protein (CRP) (p = 0.001), reduced serum albumin concentrations (p = 0.0005), and increased disease activity in JIA (p = 0.009) and IBD (p ≤ 0.08). No significant relationship between diagnosis and underlying differences in IFX clearance was observed. Multivariable analysis by covariate population pharmacokinetic modeling confirmed increased IFX clearance to be associated with anti-IFX antibody positivity, increased ESR, and reduced serum albumin concentrations. CONCLUSIONS: Enhanced IFX clearance is associated with immunogenicity and inflammatory burden across autoimmune disorders. Higher systemic IFX exposures observed in children with rheumatologic disorders are driven primarily by provider drug dose and interval selection, rather than differences in IFX pharmacokinetics across diagnoses. Despite maintenance IFX dosing at or above the standard recommended range for IBD (i.e., 5 mg/kg every 8 weeks), the dosing intensity used in the treatment of IBD is notably lower than dosing intensities used to treat JIA and uveitis, and may place some children with IBD at risk for suboptimal maintenance IFX exposures necessary for treatment response.

A Single Nucleotide Polymorphism in SLC7A5 Was Associated With Clinical Response in Multiple Myeloma Patients.

BACKGROUND/AIM: SLC7A5 is recognized as the major mediator of melphalan uptake into multiple myeloma (MM) cells; however, its contribution to the inter-patient variability of melphalan efficacy and toxicity is yet to be well elucidated. This study aimed to investigate the impact of a single nucleotide polymorphism (SNP) rs4240803 in SLC7A5 on the gene expression, ex vivo sensitivity to melphalan, and clinical outcomes in MM patients who were undergoing autologous stem cell transplantation with high-dose melphalan. MATERIALS AND METHODS: Peripheral blood mononuclear cells (PBMC) were collected from 108 MM patients prior to melphalan therapy. Clinical data were also collected from these patients following melphalan therapy. RESULTS: rs4240803 was associated with elevated expression of SLC7A5 mRNA, higher ex vivo sensitivity to melphalan in PBMCs, and positive 90-day response in these patients (p=0.047, 0.10, 0.049, respectively). CONCLUSION: rs4240803 impacted the expression of SLC7A5, thus contributing to the clinical response of MM patients to melphalan therapy.

Pharmacokinetic-Pharmacodynamic Model of Neutropenia in Patients With Myeloma Receiving High-Dose Melphalan for Autologous Stem Cell Transplant.

High-dose melphalan (HDM) is part of the conditioning regimen in patients with multiple myeloma (MM) receiving autologous stem cell transplantation (ASCT). However, individual sensitivity to melphalan varies, and many patients experience severe toxicities. Prolonged severe neutropenia is one of the most severe toxicities and contributes to potentially life-threatening infections and failure of ASCT. Granulocyte-colony stimulating factor (G-CSF) is given to stimulate neutrophil proliferation after melphalan administration. The aim of this study was to develop a population pharmacokinetic/pharmacodynamic (PK/PD) model capable of predicting neutrophil kinetics in individual patients with MM undergoing ASCT with high-dose melphalan and G-CSF administration. The extended PK/PD model incorporated several covariates, including G-CSF regimen, stem cell dose, hematocrit, sex, creatinine clearance, p53 fold change, and race. The resulting model explained portions of interindividual variability in melphalan exposure, therapeutic effect, and feedback regulation of G-CSF on neutrophils, thus enabling simulation of various doses and prediction of neutropenia duration.

Sub-10 Nanometer Feature Size in Silicon Using Thermal Scanning Probe Lithography.

High-resolution lithography often involves thin resist layers which pose a challenge for pattern characterization. Direct evidence that the pattern was well-defined and can be used for device fabrication is provided if a successful pattern transfer is demonstrated. In the case of thermal scanning probe lithography (t-SPL), highest resolutions are achieved for shallow patterns. In this work, we study the transfer reliability and the achievable resolution as a function of applied temperature and force. Pattern transfer was reliable if a pattern depth of more than 3 nm was reached and the walls between the patterned lines were slightly elevated. Using this geometry as a benchmark, we studied the formation of 10-20 nm half-pitch dense lines as a function of the applied force and temperature. We found that the best pattern geometry is obtained at a heater temperature of ∼600 °C, which is below or close to the transition from mechanical indentation to thermal evaporation. At this temperature, there still is considerable plastic deformation of the resist, which leads to a reduction of the pattern depth at tight pitch and therefore limits the achievable resolution. By optimizing patterning conditions, we achieved 11 nm half-pitch dense lines in the HM8006 transfer layer and 14 nm half-pitch dense lines and L-lines in silicon. For the 14 nm half-pitch lines in silicon, we measured a line edge roughness of 2.6 nm (3σ) and a feature size of the patterned walls of 7 nm.