josegonzalez/homebrew-php — pull request #747 by semalead (2013-09-15 09:08:04+00:00)
Title: Add php53-apcu

Seems there is no reason this formula cannot be provided for php53

Install informations says PHP should be >= 5.1.x
https://github.com/krakjoe/apcu/blob/master/INSTALL#L4-L7