Projection filter as a declared variable

Hello everyone.

I'd like to know if is possible to pass a declared variable to a projection filter. Like the example below:

declare filter nvarchar(250) := '"COMPANY" = :INPUT_COMPANY AND "DIRECT" = :INPUT_DIRECT';

filters = CE_PROJECTION(:projection1,

  ["COMPANY","DIRECT","TYPE"],

   :filter     --- Here I pass the variable that I just created above.

  );

I got a error in the line  "   :filter     --- Here I pass the variable that I just created above. "

thanks