public interface IReportPane 

Report report = Project.Current.GetItems<ReportProjectItem>().FirstOrDefault().GetReport();
var reportPane = FrameworkApplication.Panes.FindReportPanes(report).Last();
if (reportPane == null)
  return;
//Activate the pane
(reportPane as ArcGIS.Desktop.Framework.Contracts.Pane).Activate();
//Get the "ReportView" associated with the Report Pane.
ReportView reportView = reportPane.ReportView;