Ylva Terelius

N,N‐dimethylacetamide (DMA) is an organic solvent, used in busulphan, iv‐formulation, (Busulfex). DMA is metabolized primarily to N‐methylacetamide (MMA) via CYP2E1. In the present study, we investigated the pharmacokinetics and toxicity of DMA and MMA in patients, mice and cell lines. In pediatric patients (6 months to 18 years) undergoing hematopoietic stem cell transplantation, the pharmacokinetics of DMA and MMA were followed during the 4‐days Busulfex conditioning (3.2–4 mg/kg, b.i.d). No accumulation of DMA was found; however, a significant increase in clearance and a significant decrease ( p < 0.005) in half‐lives by the end of treatment were observed which might indicate CYP2E1 autoinduction. Furthermore, continuous increases in plasma concentration of MMA were observed during treatment and a terminal half‐life of 15.2 ± 1.7 h was detected. Moreover, ALT was significantly ( p = 0.04) increased in > 61% of the patients after conditioning. Additionally, mice were treated with either dimethyl sulfoxide (DMSO), DMA, busulphan in DMSO, Busulfex or saline for 4 days. DMA‐treated mice showed elevated ALT and AST values. Interestingly, Busulfex administration did not alter mice liver enzymes. Busulphan in DMA showed higher cytotoxicity compared to busulphan in DMSO in HepG‐2, Huh‐7 and HL‐60 cells. The combination Bu‐DMA‐MMA exhibited increased cytotoxicity in a concentration‐dependent manner. In conclusion, Busulfex administration to pediatric patients resulted in an accumulation of MMA during the 4‐days treatment. Busulfex is less toxic compared to Bu dissolved in DMA. MMA addition to Bu in DMA showed higher cytotoxicity. Therefore, MMA with a relatively long half‐life may induce hepatotoxicity and/or interaction with subsequently administered drugs; thus further investigations are urgently warranted.

A dataset consisting of measured values for LogD, solubility, metabolic stability in human liver microsomes (HLM) and Caco-2 permeability was used to evaluate the prediction models for lipophilicity (S+LogD), water solubility (S+Sw_pH), metabolic stability in HLM (CYP_HLM_Clint), intestinal permeability (S+Peff) and P-gp substrate identification (P-gp substrate) in the software ADMET Predictor^TM (AP) from Simulations Plus. The dataset consisted of a total of 4794 compounds, with at least data from metabolic stability determinations in HLM, from multiple discovery projects at Medivir. Our evaluation shows that the global AP models can be used for categorization of high and low values based on predicted results for metabolic stability in HLM and intestinal permeability, and to give good predictions of LogD (R²=0.79), guiding the synthesis of new compounds and for prioritzing in vitro ADME experiments. The model seems to overpredict solubility for the Medivir compounds, however. We also used the in-house datasets to build local models for LogD, solubility, metabolic stability and permeability by using artificial neural network (ANN) models in the optional Modeler^TM module of AP. Predictions of the test sets were performed with both the global and the local models and the R² value for linear regression for predicted versus measured HLM CL_int based on logarithmic data was 0.72 for the in-house model and 0.53 for the AP model. The improved predictions with the local models are likely explained both by the specific chemical space of the Medivir dataset and lab specific assay conditions for parameters which require biological assay systems. Significance Statement AP is useful early in projects for predicting and categorizing LogD, metabolic stability and permeability, to guide the synthesis of new compounds and for prioritizing in vitro ADME experiments. The building of local in-house prediction models with the optional AP Modeler Module can give improved prediction success since these models are built on data from the same experimental setup and can also be based on compounds with similar structures.

Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality in immunocompromised patients and a major etiological factor for congenital birth defects in newborns. Ganciclovir and its pro-drug valganciclovir are the preferred drugs in use today for prophylaxis and treatment of viremic patients. Due to long treatment times, patients are at risk for developing viral resistance to ganciclovir and to other drugs with a similar mechanism of action. We earlier found that the endothelin receptor B (ETBR) is upregulated during HCMV infection and that it plays an important role in the life cycle of this virus. Here, we tested the hypothesis that ETBR blockade could be used in the treatment of HCMV infection. As HCMV infection is specific to humans, we tested our hypothesis in human cell types that are relevant for HCMV pathogenesis; i.e., endothelial cells, epithelial cells and fibroblasts. We infected these cells with HCMV and treated them with the ETBR specific antagonist BQ788 or ETR antagonists that are approved by the FDA for treatment of pulmonary hypertension; macitentan, its metabolite ACT-132577, bosentan and ambrisentan, and as an anti-viral control, we used ganciclovir or letermovir. At concentrations expected to be relevant in vivo, macitentan, ACT-132577 and BQ788 effectively inhibited productive infection of HCMV. Of importance, macitentan also inhibited productive infection of a ganciclovir-resistant HCMV isolate. Our results suggest that binding or signaling through ETBR is crucial for viral replication, and that selected ETBR blockers inhibit HCMV infection.

Cathepsin K is an attractive therapeutic target for diseases in which bone resorption is excessive such as osteoporosis and osteoarthritis (OA). The current paper characterized the pharmacological profile of the potent and selective cathepsin K inhibitor, MIV-711, in vitro and in cynomolgus monkeys, and assessed translation to human based on a single dose clinical study in man. The potency and selectivity of MIV-711 were assessed in vitro using recombinant enzyme assays and differentiated human osteoclasts. MIV-711 was administered to healthy cynomolgus monkeys (3–30 µmol/kg, p.o.). Plasma levels of MIV-711 and the bone resorption biomarker CTX-I were measured after single dose experiments, and urine levels of CTX-I, NTX-I and CTX-II biomarkers were measured after repeat dose experiments. The safety, pharmacokinetics and pharmacodynamics (serum CTX-I) of MIV-711 were assessed in human healthy subjects after single ascending doses from 20 to 600 mg. MIV-711 was a potent inhibitor of human cathepsin K (Ki: 0.98 nmol/L) with > 1300-fold selectivity towards other human cathepsins. MIV-711 inhibited human osteoclast-mediated bone resorption with an IC50 value of 43 nmol/L. Single oral doses of MIV-711 to monkeys reduced plasma levels of CTX-I in a dose-dependent fashion by up to 57% at trough. The effect on CTX-I was linearly correlated to the plasma exposure of MIV-711, while the efficacy duration outlasted plasma exposure. Repeat oral dosing with MIV-711 also reduced urinary levels of the bone resorption biomarkers CTX-I (by 93%) and NTX-I (by 71%) and the cartilage degradation biomarker CTX-II (by 71%). MIV-711 was safe and well-tolerated when given as single ascending doses to healthy subjects. MIV-711 reduced serum CTX-I levels in a dose-dependent manner by up to 79% at trough. The relationship between MIV-711 exposure and effects on these biomarkers in humans was virtually identical when compared to the corresponding monkey data. MIV-711 is a potent and selective cathepsin K inhibitor with dose-dependent effects on biomarkers of bone and cartilage degradation in monkey and human. Taken together, MIV-711 shows promise for the treatment of bone and cartilage related disorders in humans, such as OA. Trial Registration EudraCT number 2011-003024-12, registered on June 22nd 2011

The role of cytochrome P450 2J2 (CYP2J2) in cyclophosphamide (Cy) bioactivation was investigated in patients, cells and microsomes. Gene expression analysis showed that CYP2J2 mRNA expression was significantly (PCYP2J2 expression showed significant upregulation (PCYP2J2 expression. Studies in HL-60 cells expressing CYP2J2 showed reduced cell viability when incubated with Cy (half maximal inhibitory concentration=3.6 mM). Inhibition of CYP2J2 using telmisartan reduced Cy bioactivation by 50% and improved cell survival. Cy incubated with recombinant CYP2J2 microsomes has resulted in apparent K_m and V_max values of 3.7–6.6 mM and 2.9–10.3 pmol/(min·pmol) CYP, respectively. This is the first study demonstrating that CYP2J2 is equally important to CYP2B6 in Cy metabolism. The heart, intestine and urinary bladder express high levels of CYP2J2; local Cy bioactivation may explain Cy-treatment-related toxicities in these organs.