Evaluation of an alternative ruxolitinib dosing regimen in patients with myelofibrosis: an open-label phase 2 study

Abstract Background Ruxolitinib improves splenomegaly and symptoms in patients with intermediate-2 or high-risk myelofibrosis; however, nearly half develop grade 3/4 anemia and/or thrombocytopenia, necessitating dose reductions and/or transfusions. We report findings from an open-label phase 2 study exploring a dose-escalation strategy aimed at preserving clinical benefit while reducing hematological adverse events early in ruxolitinib treatment. Methods Patients with myelofibrosis received ruxolitinib 10 mg twice daily (BID), with incremental increases of 5 mg BID at weeks 12 and 18 for lack of efficacy (maximum, 20 mg BID). Symptom severity was measured using the Myelofibrosis Symptom Assessment Form Total Symptom Score (MFSAF TSS). Results Forty-five patients were enrolled, 68.9% of whom had a Dynamic International Prognostic Scoring System score of 1 to 2 (i.e., intermediate-1 disease risk). Median percentage change in spleen volume from baseline to week 24 was − 17.3% (≥ 10% reduction achieved by 26 patients [57.8%]), with a clear dose response. Median percentage change in MFSAF TSS from baseline at week 24 was − 45.6%, also with a dose response. The most frequent treatment-emergent adverse events were anemia (26.7%), fatigue (22.2%), and arthralgias (20.0%). Grade 3/4 anemia (20.0%) and dose decreases due to anemia (11.1%) or thrombocytopenia (6.7%) were infrequent. Conclusions A dose-escalation approach may mitigate worsening anemia during early ruxolitinib therapy in some patients with myelofibrosis. Trial registration ClinicalTrials.gov identifier, NCT01445769 . Registered September 23, 2011.https://deepblue.lib.umich.edu/bitstream/2027.42/145195/1/13045_2018_Article_642.pd

Current and Novel Inhibitors of HIV Protease

The design, development and clinical success of HIV protease inhibitors represent one of the most remarkable achievements of molecular medicine. This review describes all nine currently available FDA-approved protease inhibitors, discusses their pharmacokinetic properties, off-target activities, side-effects, and resistance profiles. The compounds in the various stages of clinical development are also introduced, as well as alternative approaches, aiming at other functional domains of HIV PR. The potential of these novel compounds to open new way to the rational drug design of human viruses is critically assessed

Interactions in vivo between the Vif protein of HIV-1 and the precursor (Pr55GAG) of the virion nucleocapsid proteins

The abnormality of viral core structure seen in vif-defective HIV-1 grown in PBMCs has suggested a role for Vif in viral morphogenesis. Using an in vivo mammalian two-hybrid assay, the interaction between Vif and the precursor (Pr55GAG) of the virion nucleocapsid proteins has been analysed. This revealed the amino-terminal (aa 1–22) and central (aa 70–100) regions of Vif to be essential for its interaction with Pr55GAG, but deletion of the carboxy-terminal (aa 158–192) region of the protein had only a minor effect on its interaction. Initial deletion studies carried out on Pr55GAG showed that a 35-amino-acid region of the protein bridging the MA(p17)–CA(p24) junction was essential for its ability to interact with Vif. Site-directed mutagenesis of a conserved tryptophan (Trp21) near the amino terminus of Vif showed it to be important for the interaction with Pr55GAG. By contrast, mutagenesis of the highly conserved YLAL residues forming part of the BC-box motif, shown to be important in Vif promoting degradation of APOBEC3G/3F, had little or no effect on the Vif–Pr55GAG interaction

Polymorphisms in Gag spacer peptide 1 confer varying levels of resistance to the HIV- 1maturation inhibitor bevirimat

Background: The maturation inhibitor bevirimat (BVM) potently inhibits human immunodeficiency virus type 1 (HIV-1) replication by blocking capsid-spacer peptide 1 (CA-SP1) cleavage. Recent clinical trials demonstrated that a significant proportion of HIV-1-infected patients do not respond to BVM. A patient’s failure to respond correlated with baseline polymorphisms at SP1 residues 6-8. Results: In this study, we demonstrate that varying levels of BVM resistance are associated with point mutations at these residues. BVM susceptibility was maintained by SP1-Q6A, -Q6H and -T8A mutations. However, an SP1-V7A mutation conferred high-level BVM resistance and SP1-V7M and T8Δ mutations conferred intermediate levels of BVM resistance. Conclusions: Future exploitation of the CA-SP1 cleavage site as an antiretroviral drug target will need to overcome the baseline variability in the SP1 region of Gag.Publisher PDFPeer reviewe

Calcium/calmodulin inhibition of the Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 receptor kinase provides a possible link between calcium and brassinosteroid signalling

The receptor kinase BRI1 (BRASSINOSTEROID-INSENSITIVE 1) is a key component in BR (brassinosteroid) perception and signal transduction, and has a broad impact on plant growth and development. In the present study, we demonstrate that Arabidopsis CaM (calmodulin) binds to the recombinant cytoplasmic domain of BRI1 in a Ca2+-dependent manner in vitro. In silico analysis predicted binding to Helix E of the BRI1 kinase subdomain VIa and a synthetic peptide based on this sequence interacted with Ca2+/CaM. Co-expression of CaM with the cytoplasmic domain of BRI1 in Escherichia coli strongly reduced autophosphorylation of BRI1, in particular on tyrosine residues, and also reduced the BRI1-mediated transphosphorylation of E. coli proteins on tyrosine, threonine and presumably serine residues. Several isoforms of CaM and CMLs (CaM-like proteins) were more effective (AtCaM6, AtCaM7 and AtCML8, where At is Arabidopsis thaliana) than others (AtCaM2, AtCaM4 and AtCML11) when co-expressed with BRI1 in E. coli. These results establish a novel assay for recombinant BRI1 transphosphorylation activity and collectively uncover a possible new link between Ca2+ and BR signalling

Molecular System Bioenergics of the Heart: Experimental Studies of Metabolic Compartmentation and Energy Fluxes versus Computer Modeling †

In this review we analyze the recent important and remarkable advancements in studies of compartmentation of adenine nucleotides in muscle cells due to their binding to macromolecular complexes and cellular structures, which results in non-equilibrium steady state of the creatine kinase reaction. We discuss the problems of measuring the energy fluxes between different cellular compartments and their simulation by using different computer models. Energy flux determinations by 18O transfer method have shown that in heart about 80% of energy is carried out of mitochondrial intermembrane space into cytoplasm by phosphocreatine fluxes generated by mitochondrial creatine kinase from adenosine triphosphate (ATP), produced by ATP Synthasome. We have applied the mathematical model of compartmentalized energy transfer for analysis of experimental data on the dependence of oxygen consumption rate on heart workload in isolated working heart reported by Williamson et al. The analysis of these data show that even at the maximal workloads and respiration rates, equal to 174 μmol O2 per min per g dry weight, phosphocreatine flux, and not ATP, carries about 80–85% percent of energy needed out of mitochondria into the cytosol. We analyze also the reasons of failures of several computer models published in the literature to correctly describe the experimental data