A phase I dose-escalation study of enzalutamide in combination with the AKT inhibitor AZD5363 (capivasertib) in patients with metastatic castration-resistant prostate cancer.

BACKGROUND: Activation of the PI3K/AKT/mTOR pathway through loss of phosphatase and tensin homolog (PTEN) occurs in approximately 50% of patients with metastatic castration-resistant prostate cancer (mCRPC). Recent evidence suggests that combined inhibition of the androgen receptor (AR) and AKT may be beneficial in mCRPC with PTEN loss. PATIENTS AND METHODS: mCRPC patients who previously failed abiraterone and/or enzalutamide, received escalating doses of AZD5363 (capivasertib) starting at 320 mg twice daily (b.i.d.) given 4 days on and 3 days off, in combination with enzalutamide 160 mg daily. The co-primary endpoints were safety/tolerability and determining the maximum tolerated dose and recommended phase II dose; pharmacokinetics, antitumour activity, and exploratory biomarker analysis were also evaluated. RESULTS: Sixteen patients were enrolled, 15 received study treatment and 13 were assessable for dose-limiting toxicities (DLTs). Patients were treated at 320, 400, and 480 mg b.i.d. dose levels of capivasertib. The recommended phase II dose identified for capivasertib was 400 mg b.i.d. with 1/6 patients experiencing a DLT (maculopapular rash) at this level. The most common grade ≥3 adverse events were hyperglycemia (26.7%) and rash (20%). Concomitant administration of enzalutamide significantly decreased plasma exposure of capivasertib, though this did not appear to impact pharmacodynamics. Three patients met the criteria for response (defined as prostate-specific antigen decline ≥50%, circulating tumour cell conversion, and/or radiological response). Responses were seen in patients with PTEN loss or activating mutations in AKT, low or absent AR-V7 expression, as well as those with an increase in phosphorylated extracellular signal-regulated kinase (pERK) in post-exposure samples. CONCLUSIONS: The combination of capivasertib and enzalutamide is tolerable and has antitumour activity, with all responding patients harbouring aberrations in the PI3K/AKT/mTOR pathway. CLINICAL TRIAL NUMBER: NCT02525068.

Vistusertib (dual m-TORC1/2 inhibitor) in combination with paclitaxel in patients with high-grade serous ovarian and squamous non-small-cell lung cancer.

Background: We have previously shown that raised p-S6K levels correlate with resistance to chemotherapy in ovarian cancer. We hypothesised that inhibiting p-S6K signalling with the dual m-TORC1/2 inhibitor in patients receiving weekly paclitaxel could improve outcomes in such patients. Patients and methods: In dose escalation, weekly paclitaxel (80 mg/m2) was given 6/7 weeks in combination with two intermittent schedules of vistusertib (dosing starting on the day of paclitaxel): schedule A, vistusertib dosed bd for 3 consecutive days per week (3/7 days) and schedule B, vistusertib dosed bd for 2 consecutive days per week (2/7 days). After establishing a recommended phase II dose (RP2D), expansion cohorts in high-grade serous ovarian cancer (HGSOC) and squamous non-small-cell lung cancer (sqNSCLC) were explored in 25 and 40 patients, respectively. Results: The dose-escalation arms comprised 22 patients with advanced solid tumours. The dose-limiting toxicities were fatigue and mucositis in schedule A and rash in schedule B. On the basis of toxicity and pharmacokinetic (PK) and pharmacodynamic (PD) evaluations, the RP2D was established as 80 mg/m2 paclitaxel with 50 mg vistusertib bd 3/7 days for 6/7 weeks. In the HGSOC expansion, RECIST and GCIG CA125 response rates were 13/25 (52%) and 16/25 (64%), respectively, with median progression-free survival (mPFS) of 5.8 months (95% CI: 3.28-18.54). The RP2D was not well tolerated in the SqNSCLC expansion, but toxicities were manageable after the daily vistusertib dose was reduced to 25 mg bd for the following 23 patients. The RECIST response rate in this group was 8/23 (35%), and the mPFS was 5.8 months (95% CI: 2.76-21.25). Discussion: In this phase I trial, we report a highly active and well-tolerated combination of vistusertib, administered as an intermittent schedule with weekly paclitaxel, in patients with HGSOC and SqNSCLC. Clinical trial registration: ClinicialTrials.gov identifier: CNCT02193633.

A phase I/II trial of AT9283, a selective inhibitor of aurora kinase in children with relapsed or refractory acute leukemia: challenges to run early phase clinical trials for children with leukemia.

Aurora kinases regulate mitosis and are commonly overexpressed in leukemia. This phase I/IIa study of AT9283, a multikinase inhibitor, was designed to identify maximal tolerated doses, safety, pharmacokinetics, and pharmacodynamic activity in children with relapsed/refractory acute leukemia. The trial suffered from poor recruitment and terminated early, therefore failing to identify its primary endpoints. AT9283 caused tolerable toxicity, but failed to show clinical responses. Future trials should be based on robust preclinical data that provide an indication of which patients may benefit from the experimental agent, and recruitment should be improved through international collaborations and early combination with established treatment strategies.

A multicentre, multicycle audit of the prescribing practices of three paediatric dental departments in the North of England.

BACKGROUND: Odontogenic infections are frequently treated with antimicrobials. The inappropriate use of these medications has led to bacterial resistance and the development of species which are resistant to the antimicrobials currently available. This has serious implications for global public health. AIM: A multicycle clinical audit was carried out to compare the prescribing practices of three paediatric dental departments in the North of England. RESULTS: Results revealed deficiencies in prescribing practices in all three centres. Following education and the provision of an aide-memoire in subsequent cycles, improvements were seen in appropriateness of prescribing, increasing from 28% in the first cycle, to 71% in the third cycle.

Purinergic 2X1 receptors mediate endothelial dependent vasodilation to ATP.

ATP is an important endogenous mediator in the cardiovascular system. It induces endothelium dependent vasodilation, but the precise receptor pathway activated in this response is currently under debate. We have used traditional bioassay techniques to show that ATP-induced vasodilation in mesenteric vessels is endothelium-dependent. Furthermore, ATP-induced vasodilation was inhibited by both suramin and 2',3'-O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP), consistent with a P2X(1)-, P2X(2)-, or P2X(3)-mediated event and was not potentiated by ivermectin, indicating that these responses were not P2X(4) receptor-mediated. ATP did not induce vasodilation in vessels from P2X (-/-)(1) mice, confirming an absolute requirement for this receptor. Finally, in pure cell populations of mouse mesenteric artery endothelial cells, we show that P2X(1) mRNA is specifically expressed. However, in line with observations in the brain, the P2X(1) present in endothelial cells does not seem to be recognized by conventional antibodies. Together, these results show that ATP-induced vasodilation is mediated by P2X(1) receptor activation on mesenteric arterial endothelial cells. These observations establish a critical role for P2X(1) receptors in the ATP vasodilator pathway.

Relative receptor expression is a determinant in xenobiotic-mediated CYP3A induction in rat and human cells.

1. Species differences in xenobiotic-mediated transcriptional activation of CYP3A genes are known to exist. These differences are proposed to be due, in part, to host cell differences. 2. Host cell effects were investigated by trans-species transient transfection of reporter genes containing either the rat CYP3A23 or human CYP3A4 proximal promoters into human HepG2 and rat FaO and H4IIEC3 hepatoma cells. HepG2 and FaO cells supported activation of both CYP3A constructs by xenobiotics in a species-specific manner, whereas H4IIEC3 cells were non-permissive. 3. The mRNA complement of the cell lines was then quantified by semiquantitative RT-PCR for adult CYP3As (CYP3A23, CYP3A4/5), steroid hormone receptors (constitutive androstane receptor, glucocorticoid receptor-alpha, pregnane X receptor) and transcription factors (Hepatic nuclear factor 4alpha, retinoid X receptor). 4. Principal component analysis of absolute receptor levels demonstrated a wide scattering, with no coherent pattern. In contrast, PCA of relative receptor ratios segregated H4IIEC3 cells from all other samples. 5. The observation is confirmed that species differences in response to xenobiotics are a result of host cell environment. In addition, new evidence is provided to support the hypothesis that in addition to individual receptor activation profiles, the relative abundance of steroid hormone receptors that control CYP3A gene expression play an important role in this observed species difference.

Receptor-dependent transcriptional activation of cytochrome P4503A genes: induction mechanisms, species differences and interindividual variation in man.

1. The importance of CYP3A enzymes in drug metabolism and toxicology has yielded a wealth of information on the structure, function and regulation of this subfamily and recent research emphasis has been placed on the human forms, namely CYP3A4, CYP3A5, CYP3A7 and CYP3A43. 2. The current review will focus on the receptor-dependency of CYP3A regulation and includes consideration of the regulatory roles of the glucocorticoid (GR), pregnane X (PXR) and constitutive androstane (CAR) receptors. 3. Emphasis has been placed on the topics of expression and substrate specificity, assessment of induction, species differences in induction, CYP3A promoter sequences and regulation of gene expression, structural and functional aspects of receptor-mediated, CYP3A gene activation, receptor variants and interindividual variation in human CYP3A expression, the latter encompassing environmental, physiological and genetic aspects. 4. An outline of future research needs will be discussed in the context of receptor-mediated molecular mechanisms of CYP3A gene regulation and the impact on interindividual variations in CYP3A expression. 5. Taken collectively, this review highlights the importance of understanding the molecular mechanisms of CYP3A induction as a means of rationalizing human responses to many clinically used drugs, in addition to providing a mechanistically coherent platform to understand and predict interindividual variations in response and drug-drug interactions.

Use of suppression-PCR subtractive hybridisation to identify genes that demonstrate altered expression in male rat and guinea pig livers following exposure to Wy-14,643, a peroxisome proliferator and non-genotoxic hepatocarcinogen.

Understanding the genetic profile of a cell at all stages of normal and carcinogenic development should provide an essential aid to developing new strategies for the prevention, early detection, diagnosis and treatment of cancers. We have attempted to identify some of the genes that may be involved in peroxisome-proliferator (PP)-induced non-genotoxic hepatocarcinogenesis using suppression PCR subtractive hybridisation (SSH). Wistar rats (male) were chosen as a representative susceptible species and Duncan-Hartley guinea pigs (male) as a resistant species to the hepatocarcinogenic effects of the PP, [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (Wy-14,643). In each case, groups of four test animals were administered a single dose of Wy-14,643 (250 mg/kg per day in corn oil) by gastric intubation for 3 consecutive days. The control animals received corn oil only. On the fourth day the animals were killed and liver mRNA extracted. SSH was carried out using mRNA extracted from the rat and guinea pig livers, and used to isolate genes that were up and downregulated following Wy-14,643 treatment. These genes included some predictable (and hence positive control) species such as CYP4A1 and CYP2C11 (upregulated and downregulated in rat liver, respectively). Several genes that may be implicated in hepatocarcinogenesis have also been identified, as have some unidentified species. This work thus provides a starting point for developing a molecular profile of the early effects of a non-genotoxic carcinogen in sensitive and resistant species that could ultimately lead to a short-term assay for this type of toxicity.

GENETIC VARIATION IN A FUNGAL PATHOGEN: RESPONSE TO HOST DEFENSIVE CHEMICALS.

In response to infection by shoot infecting pathogens, Scots pine releases cortical resin into affected tissues. The resin contains a mixture of monoterpene compounds (α-pinene, ß-pinene, 3-carene, ß-myrcene, limonene and ß-phellandrene) that retard the growth of a range of pathogens. The proportion of each monoterpene in the resin shows substantial variation among trees within a population. Thus pathogens on different trees encounter quite different monoterpene environments. To investigate the evolutionary response of pathogens to the chemically heterogeneous environment provided by Scots pine, isolates of the ascomycete canker pathogen Crumenulopsis sororia were collected from trees within a range of natural Scots pine populations. Growth rates of these isolates were measured in the presence and absence of five host monoterpenes. Substantial heritable variation for growth rate in the presence and absence of monoterpenes, and for monoterpene tolerance was recorded, suggesting the potential for the evolution of chemically specialized pathogen subpopulations on different trees within a wood. However, genetic correlations between growth rates in different monoterpene environments and between tolerance of different monoterpenes were either positive or non-significant, and there was no evidence of "tradeoffs" in performance under different monoterpene regimes. The results suggest that, on its own, the presence of monoterpene variability within Scots pine will not lead to disruptive selection on the C. sororia population. The relationship between defensive chemical diversity and pest resistance is discussed in the light of these results.