Get the value of checkbox in wpf

Below is the xaml code I'm using. I'm trying to get the checkbox value in code-behind.

<ListBox ItemsSource="{Binding AvailablePresentationObjects}" >
  <ListBox>
    <CheckBox Content="Puma" IsChecked="{Binding IsChecked}"/>
    <CheckBox Content="NIke" IsChecked="{Binding IsChecked}"/>
    <CheckBox Content="Adidas" IsChecked="{Binding IsChecked}"/>
    <CheckBox Content="reebok" IsChecked="{Binding IsChecked}"/>
  </ListBox>
</ListBox>
<Button x:Name="btnLaunchCache" HorizontalAlignment="Right" 
        IsEnabled="{Binding Path=IsButtonEnabled,Mode=TwoWay}" 
        Click="BtnLaunchCache_Click">
<TextBlock>Submit</TextBlock>