Expecting something between ')' and the 'AS' keyword

Question

I am trying to run the update query below in Teradata but getting an error message 'Expecting something between ')' and the 'AS' keyword. I am missing anything? I have checked some previous update and it worked for other developers in my company.

 WHEN MATCHED THEN UPDATE SET


 PRSCRBR_LAST_NM = COALESCE(M.PRESCRIBER_LAST_NAME,'ZZZZ1') AS PRSCRBR_LAST_NM,

Thanks