The Sanitize class is deprecated as of 2.4, and will be removed in CakePHP 3.0. Instead of using the Sanitize class you can accomplish the same tasks using other parts of CakePHP, native PHP functions, or other libraries.
Instead of using the destructive input filtering features of Sanitize class you should instead apply more thorough Data Validation to the user data your application accepts. By rejecting invalid input you can often remove the need to destructively modify user data. You might also want to look at PHP’s filter extension in situations you need to modify user input.
Often input filtering is used when accepting user-submitted HTML. In these situations it is best to use a dedicated library like HTML Purifier.