XML schema restriction pattern for not allowing specific string

I have implement XSD schema with restriction in a field. Field doesn't a value with string FILENAME:

eg:

FILENAME

ORIGINFILENAME

FILENAMETEST

123FILENAME456

This values doesn't valid values.

This regular expression is valid for my case /^((?!FILENAME).)*$ but the XSD pattern does not support Negative Lookahead.

How implement XSD pattern restriction equal /^((?!FILENAME).)*$ ?

Thank you