In May 2008, Allen was diagnosed with a malignant glioma brain tumor and immediately underwent clinical trials, chemotherapy and radiation treatments at the Cedars-Sinai Maxine Dunitz Neurosurgical Institute.

Allen was a founding member of Lit over two decades ago and was able to perform with the band until last fall. In a statement from Kevin Baldes, Jeremy Popoff, and A. Jay Popoff, the band had this to say of their longtime friend Allen:

\"To know Al was to know laughter. He had a heart of gold and would do anything for anyone. Words cannot begin to express how much he will be missed. This was our brother and not a day will go by that we won\'t think about him. Right now we\'re trying to find the balance of mourning his loss and celebrating his life. Allen has experienced more in his 39 years than most people dream of in ten lifetimes. This is a tremendous loss for us, our fans, and also for Allen\'s family who took such good care of him during his battle with cancer.\"

Allen is survived by his daughter Giovanna Mackey, his mother Connie James, and his father Paul Shellenberger.

A tribute video to Allen can be seen below: