Simultaneous inhibition of ATR and PARP sensitizes colon cancer cell lines to irinotecan

Enhanced DNA damage repair is one mechanism involved in colon cancer drug resistance. Thus, targeting molecular components of repair pathways with specific small molecule inhibitors may improve the efficacy of chemotherapy. ABT-888 and VE-821, inhibitors of poly-ADP-ribose-polymerase (PARP) and the serine/threonine-kinase Ataxia telangiectasia related (ATR), respectively, were used to treat colon cancer cell lines in combination with the topoisomerase-I inhibitor irinotecan (SN38). Our findings show that each of these DNA repair inhibitors utilized alone at nontoxic single agent concentrations resulted in sensitization to SN38 producing a 1.4-3 fold reduction in the 50% inhibitory concentration (IC50) of SN38 in three colon cancer cell lines. When combined together, nontoxic concentrations of ABT-888 and VE-821 produced a 4.5-27 fold reduction in the IC50 of SN38 with the HCT-116 colon cancer cells demonstrating the highest sensitization as compared to LoVo and HT-29 colon cancer cells. Furthermore, the combination of all three agents was associated with maximal G(2) -M arrest and enhanced DNA-damage (gamma H2AX) in all three colon cancer cell lines. The mechanism of this enhanced sensitization was associated with: (a) maximal suppression of SN38 induced PARP activity in the presence of both inhibitors and (b) ABT-888 producing partial abrogation of the VE-821 enhancement of SN38 induced DNA-PK phosphorylation, resulting in more unrepaired DNA damage; these alterations were only present in the HCT-116 cells which have reduced levels of ATM. This novel combination of DNA repair inhibitors may be useful to enhance the activity of DNA damaging chemotherapies such as irinotecan and help produce sensitization to this drug in colon cancer

Antithrombotic Management and Outcomes of Anterior ST-Elevation Myocardial Infarction With New-Onset Wall Motion Abnormalities in Men and Women

Background: In patients with anterior ST-elevation myocardial infarction (STEMI) and new-onset antero-apical wall motion abnormalities (WMAs), whether the rate of prophylaxis against left ventricular thrombus and outcomes differ between men and women is unknown. Methods: A multicentre retrospective cohort study of patients with STEMI and new-onset antero-apical WMAs treated with primary percutaneous coronary intervention was conducted. Patients with an established indication of oral anticoagulation (OAC) were excluded. The rates of triple therapy (double antiplatelet therapy + OAC) at discharge were compared for women vs men. The rates of net adverse clinical events, a composite of mortality, myocardial infarction, stroke or transient ischemic attack, systemic thromboembolism or Bleeding Academic Research Consortium (BARC) type 3 or 5 bleeding at 6 months were compared across sex using a multivariate logistic regression model. Results: A total of 1664 patients were included in the primary analysis, of whom 402 (24.2%) were women and 1262 (75.8%) were men. A total of 138 women (34.3%) and 489 men (38.7%) received a triple therapy prescription at discharge (P = 0.11). At 6 months, 33 women (8.2%) and 96 men (7.6%) experienced a net adverse clinical event (adjusted odds ratio 0.82; 95% confidence interval 0.49-1.37). No difference occurred in the risk of bleeding events and ischemic events between men and women, when these were analyzed separately. Conclusions: The rates of OAC prescription for left ventricular thrombus prophylaxis and clinical outcomes at 6 months were similar in women and men following anterior STEMI with new-onset antero-apical WMAs. Résumé: Contexte: On ignore si le taux de prophylaxie contre le thrombus ventriculaire gauche et les résultats thérapeutiques diffèrent entre les hommes et les femmes qui ont subi un infarctus du myocarde avec élévation du segment ST (STEMI) antérieur et ont des anomalies du mouvement pariétal (AMP) antéroapical d’apparition récente. Méthodes: Nous avons mené une étude de cohorte rétrospective multicentrique auprès de patients qui ont subi un STEMI et ont des AMP d’apparition récente traitées par une intervention coronarienne percutanée primaire. Nous avons exclu les patients chez lesquels il existait une indication établie à l’anticoagulation orale (ACO). Nous avons comparé les taux de trithérapie (bithérapie antiplaquettaire + ACO) à la sortie de l’hôpital entre les femmes et les hommes. Nous avons comparé les taux d’événements indésirables cliniques nets, le critère composite de mortalité, d’infarctus du myocarde, d’accident vasculaire cérébral ou d’accident ischémique transitoire, la thromboembolie systémique ou l’hémorragie de type 3 ou 5 selon le Bleeding Academic Research Consortium (BARC) après 6 mois entre les sexes au moyen du modèle de régression logistique multivariée. Résultats: Au sein des 1 664 patients de l’analyse principale, 402 (24,2 %) étaient des femmes et 1262 (75,8 %) étaient des hommes. Un total de 138 femmes (34,3 %) et de 489 hommes (38,7 %) ont reçu une ordonnance de trithérapie à la sortie de l’hôpital (P = 0,11). Après 6 mois, 33 femmes (8,2 %) et 96 hommes (7,6 %) ont subi un événement indésirable net (rapport de cotes ajusté 0,82 ; intervalle de confiance à 95 % 0,49-1,37). Aucune différence n’a été notée dans le risque d’événements hémorragiques et d’événements ischémiques entre les hommes et les femmes lorsque ces événements étaient analysés séparément. Conclusions: Les taux d’ordonnances d’ACO en prophylaxie du thrombus ventriculaire gauche et les résultats cliniques après 6 mois étaient similaires entre les femmes et les hommes à la suite du STEMI antérieur et des AMP antéroapicale d’apparition récente