KEYNOTE-590: Phase III study of first-line chemotherapy with or without pembrolizumab for advanced esophageal cancer.

BACKGROUND: Treatment options for patients with advanced esophageal or esophagogastric junction (EGJ) cancer are limited. Current guidelines for first-line treatment of advanced esophageal or EGJ cancer recommend chemotherapy containing a platinum and a fluoropyrimidine agent. Pembrolizumab demonstrated antitumor activity in previously treated patients with advanced esophageal cancer and in patients with gastroesophageal junction cancer. AIM: To describe the design and rationale for the randomized, double-blind, placebo-controlled Phase III KEYNOTE-590 study, which will be conducted to investigate pembrolizumab in combination with chemotherapy as first-line treatment in patients with advanced esophageal or EGJ cancer. Clinical trial registry & ID: ClinicalTrials.gov : NCT03189719.

Absence of irreversible effects of aliskiren in standard juvenile rat toxicity studies.

BACKGROUND: Aliskiren is the first orally bioavailable direct renin inhibitor approved for the treatment of hypertension in adults. Juvenile toxicity studies in rats were initiated to support treatment in the pediatric population. METHODS: In Study 1, aliskiren oral administration was initiated on postpartum day (PPD) 14, after nephrogenesis was completed, and continued through PPD 70 at doses of 0, 30, 100, and 300 mg/kg/day. In-life, clinical pathology, anatomic pathology, developmental, behavioral, reproductive, and toxicokinetics evaluations were performed. In Study 2, oral administration was initiated on PPD 8, before completion of nephrogenesis, and continued through PPD 35/36. In-life, clinical pathology, anatomic pathology, developmental, and toxicokinetics evaluations were performed. RESULTS: With dosing initiated on PPD 8, mortality at 100 and 300 mg/kg/day and slightly increased kidney weight at 100 mg/kg/day occurred. Decreased absolute lymphocyte count at 300 mg/kg/day at the end of dosing occurred with dosing initiated on PPD 14. There were clinical signs and transient effects on body weight gains in both studies. There were no changes in other parameters. Systemic exposure was much higher on PPD 8 and 14 compared with adult rats on PPD 64. CONCLUSIONS: All effects produced by aliskiren, including kidney effects, were reversible. Increased exposure in very young animals is considered to be the result of immature drug transporter systems.

Aliskiren toxicity in juvenile rats is determined by ontogenic regulation of intestinal P-glycoprotein expression.

Juvenile rat toxicity studies with the direct renin inhibitor aliskiren were initiated to support treatment in the pediatric population. In Study 1, aliskiren was administered orally to juvenile rats at doses of 0, 30, 100 or 300 mg/kg/day with repeated dosing from postpartum day (PPD) 8 to PPD 35/36. In-life, clinical pathology, anatomic pathology, and toxicokinetics evaluations were performed. In Study 2, single oral doses of aliskiren (0, 100 or 300 mg/kg) were given to 14-, 21-, 24-, 28-, 31- or 36-day-old rats; in-life data and toxicokinetics were evaluated. Study 3 was a single dose (3 mg/kg i.v.) pharmacokinetic study in juvenile rats on PPD 8, 14, 21 and 28. In Study 4, naïve rats were used to investigate ontogenic changes of the multidrug-resistant protein 1 (MDR1) and the organic anion transporting polypeptide (OATP) mRNA in several organs. Oral administration of aliskiren at 100 and 300 mg/kg caused unexpected mortality and severe morbidity in 8-day-old rats. Aliskiren plasma and tissue concentrations were increased in rats aged 21days and younger. Expression of MDR1 and OATP mRNA in the intestine, liver and brain was significantly lower in very young rats. In conclusion, severe toxicity and increased exposure in very young rats after oral administration of aliskiren are considered to be the result of immature drug transporter systems. Immaturity of MDR1 in enterocytes appears to be the most important mechanism responsible for the high exposure.

The use of rat lens explant cultures to study the mechanism of drug-induced cataractogenesis.

Lens explant cultures were used to assess the mechanism of drug-induced cataractogenic potential of NVS001, a peroxisome proliferator-activated receptor delta (PPARδ) agonist, which resulted in cataract in all treated animals during a 13-week rat study. Ciglitazone, a PPARγ agonist and cataractogenic compound, was used as a positive control to validate this model. Rat lenses were extracted and cultured in medium supplemented with antibiotics for 24-h preincubation pretreatment. Lenses showing no signs of damage at the end of the preincubation pretreatment period were randomized into five experimental groups, (1) untreated control, (2) 0.1% dimethyl sulphoxide control, (3) 10µM NVS001, (4) 10µM ciglitazone, and (5) 10µM acetaminophen (negative control). Lenses were treated every 24 h after preincubation pretreatment for up to 48 h. Samples for viability, histology, and gene expression profiling were collected at 4, 24, and 48 h. There was a time-dependent increase in opacity, which correlated to a decrease in viability measured by adenosine triphosphate levels in NVS001 and ciglitazone-treated lenses compared with controls. NVS001 and ciglitazone had comparable cataractogenic effects after 48 h with histology showing rupture of the lens capsule, lens fiber degeneration, cortical lens vacuolation, and lens epithelial degeneration. Furthermore, no changes were seen when lenses were treated with acetaminophen. Gene expression analysis supported oxidative and osmotic stress, along with decreases in membrane and epithelial cell integrity as key factors in NVS001-induced cataracts. This study suggests that in vitro lens cultures can be used to assess cataractogenic potential of PPAR agonists and to study/understand the underlying molecular mechanism of cataractogenesis in rat.

Correlation of major cytogenetic response with a pharmacogenetic marker in chronic myeloid leukemia patients treated with imatinib (STI571).

PURPOSE: Imatinib, an inhibitor of the Bcr-Abl tyrosine kinase, is indicated for the treatment of patients with Philadelphia chromosome-positive chronic myeloid leukemia. We examined genotypes from patients enrolled in the International Randomized Study of IFN-alpha versus STI571 in an attempt to identify factors that associate with cytogenetic response. EXPERIMENTAL DESIGN: Sixty-eight polymorphic loci in 26 genes were examined in a subset of 187 patients (imatinib-treated patients, n = 113; IFN + 1-beta-D-arabinofuranosylcytosine-treated patients, n = 74). Correlations between genotype and major cytogenetic response (MCyR) were examined by Fisher's exact tests. Multivariate and survival analyses were also performed. RESULTS: A significant association between MCyR and the rs2290573 polymorphism mapped to 15q22.33 was observed in imatinib-treated patients (P = 0.00037, Bonferroni corrected P = 0.025). Individuals with a CC genotype at this locus had a MCyR rate of 52% compared with individuals with a CT or TT genotype that had a MCyR rate of 89% (odds ratio, 6.72; 95% confidence interval, 1.51-29.91). In a multivariate analysis, the rs2290573 polymorphism was significant, whereas Sokal score was not. Time to progression analysis illustrated a significant difference based on genotype for the rs2290573 polymorphism. CONCLUSIONS: A significant association was identified between the genetic polymorphism rs2290573 and MCyR in imatinib-treated patients. This polymorphism is located in the intronic sequence of a putative gene with a tyrosine kinase domain. Multivariate analysis suggests that an individual's genotype for rs2290573 has more predictive value for MCyR than prognostic variables such as Sokal score. The clinical relevance of these results requires validation in future clinical trials.

Pharmacogenomic analysis of cytogenetic response in chronic myeloid leukemia patients treated with imatinib.

PURPOSE: To better understand the molecular basis of cytogenetic response in chronic myeloid leukemia patients treated with imatinib, we studied gene expression profiles from a total of 100 patients from a large, multinational Phase III clinical trial (International Randomized Study of IFN-alpha versus STI571). EXPERIMENTAL DESIGN: Gene expression data for >12,000 genes were generated from whole blood samples collected at baseline (before imatinib treatment) using Affymetrix oligonucleotide microarrays. Cytogenetic response was determined based on the percentage of Ph(+) cells from bone marrow following a median of 13 months of treatment. RESULTS: A genomic profile of response was developed using a subset of individuals that exhibited the greatest divergence in cytogenetic response; those with complete response (0% Ph(+) cells; n = 53) and those with minimal or no response (>65% Ph(+) cells; n = 13). A total of 55 genes was identified that were differentially expressed between these two groups. Using a "leave-one-out" strategy, we identified the optimum 31 genes from this list to use as our genomic profile of response. Using this genomic profile, we were able to distinguish between individuals that achieved major cytogenetic response (0-35% Ph(+) cells) and those that did not, with a sensitivity of 93.4% (71 of 76 patients), specificity of 58.3% (14 of 24 patients), positive predictive value of 87.7%, and negative predictive value of 73.7%. CONCLUSIONS: Interestingly, many of the genes identified appear to be strongly related to reported mechanisms of BCR-ABL transformation and warrant additional research as potential drug targets. The validity and clinical implications of these results should be explored in future studies.

Acid-sensing ion channels in malignant gliomas.

High grade glioma cells derived from patient biopsies express an amiloride-sensitive sodium conductance that has properties attributed to the human brain sodium channel family, also known as acid-sensing ion channels (ASICs). This amiloride-sensitive conductance was not detected in cells obtained from normal brain tissue or low grade or benign tumors. Differential gene profiling data showed that ASIC1 and ASIC2 mRNA were present in normal and low grade tumor cells. Although ASIC1 was present in all of the high grade glial cells examined, ASIC2 mRNA was detected in less than half. The main purpose of our work was to examine the molecular mechanisms that may underlie the constitutively activated sodium currents present in high grade glioma cells. Our results show that 1) gain-of-function mutations of ASIC1 were not present in a number of freshly resected and cultured high grade gliomas, 2) syntaxin 1A inhibited ASIC currents only when ASIC1 and ASIC2 were co-expressed, and 3) the inhibition of ASIC currents by syntaxin 1A had an absolute requirement for either gamma- or delta-hENaC. Transfection of cultured cells originally derived from high grade gliomas (U87-MG and SK-MG1) with ASIC2 abolished basal amiloride-sensitive sodium conductance; this inhibition was reversed by dialysis of the cell interior with Munc-18, a syntaxin-binding protein that typically blocks the interaction of syntaxin with other proteins. Thus, syntaxin 1A cannot inhibit Na(+) permeability in the absence of adequate plasma membrane ASIC2 expression, accounting for the observed functional expression of amiloride-sensitive currents in high grade glioma cells.