Removing Middle Name in Excel?

I'm working with a large amount of data and employee names, and all sources of the employee's name are in a lastname, firstname format, except for one source, which is lastname, first name middle name. Is there a formula that will allow me to remove the middle names so that my references to those sources will match up? Example) in cell A1, I have Johnson, Edward Mark III. How can I change this to display Johnson, Edward?