In the spring of 2005 Andrew McMahon and his band Jack's Mannequin embarked on their first US headlining tour. Before the tour was completed, McMahon paid a visit to his voice doctor in New York City with a list of health concerns. The following morning the results of his blood work landed him in the hospital where he was soon diagnosed with Acute Lymphatic Leukemia. Through the summer of 2005 McMahon underwent two rounds of chemotherapy, radiation treatment and with a stroke of good luck, a stem cell transplant from his sister. Having spent the end of 2005 and the beginning of 2006 recuperating at home McMahon began playing occasional shows around town as well as short headlining runs in support of Jack's Mannequin's first major release, Everything in Transit. In an effort to raise money and awareness for cancer research, Andrew founded the Dear Jack Foundation in July 2006.

McMahon’s newly formed Dear Jack Foundation will be working to find the organizations and charities with the greatest need and highest potential for impact. Amongst the recipients are the UCLA stem cell transplant program who are on the cutting edge of cures through transplantation, the Leukemia & Lymphoma Society, and the Pediatric Cancer Research Foundation.

This is a cause that means a great deal to McMahon and he is constantly working on opportunities to drive money and awareness to the programs and charities that fight on the front lines against these diseases. We thank you for your consideration and involvement. Leukemia is finding new victims everyday in demographics that were otherwise untouched as few as two or three years ago. This disease is desperate for research and with your help we can save lives.