Symphony Summit has an API that can be used to create incidents. There are a number of methods to integrate QRadar with external products, such as a right-click option in the user interface, creating an app for QRadar, or event a Custom Action Script to send an API post based on the offense name.
I think a custom action script is likely the easiest method here, as you can get Rule Reponse for the Offense to run a post with the API key from your Symphony Summit instance and send the offense details.
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Jonathan Pechta
QRadar Support Content Lead
Support forums: ibm.biz/qradarforums
jonathan.pechta1@ibm.com------------------------------