FetchTask: Asynchronous task return?

Hi,

I have a Teams bot with composeExtensions. When user selects one of these commands, I receive an event in my bot code:   function 'handleTeamsMessagingExtensionFetchTask'
There I return a task to show a web page in Teams browser

My question: I need to do some asynchronous code before returning the task, is it possible?

Thanks,
Diego