1. Oncology Research Unit, Pfizer Global Research and Development, San Diego, CA 92121, USA.
2. Departments of Radiation Oncology and Medical Biophysics, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 2M9, Canada.
3. Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada.
4. Division of Gastroenterology, Department of Medicine, Tufts Medical Center, Boston, MA 02111, USA.
5. University Health Network, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
6. Pfizer Biotherapeutics Clinical Research, Cambridge, MA 02140, USA.