1. Division of Clinical Studies, The Institute of Cancer Research, Sutton, Surrey, UK
2. Present address: Cell Signalling Group, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, UK
3. Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, Signal Transduction and Molecular Pharmacology Team, The Institute of Cancer Research, Sutton, Surrey, UK
4. Department of Neurology, Pediatrics, Neurosurgery, Brain Tumor Research Center and Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
5. Cancer Research UK Cancer Therapeutics Unit, Clinical Pharmacology and Trials Team, Sutton, Surrey, UK
6. Present address: MRC Cancer Unit, University of Cambridge, Cambridge, UK
7. Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, Target Selection and Hit Discovery Team, The Institute of Cancer Research, Sutton, Surrey, UK
8. Cancer Research UK & Engineering and Physical Sciences Research Council Cancer Imaging Centre, The Institute of Cancer Research, Sutton, Surrey, UK
9. Novartis Pharma AG, Basel, Switzerland
10. Present address: Basilea Pharmaceutica International AG, Basel, Switzerland
11. The Royal Marsden NHS Trust, Children and Young People's Unit, Sutton, Surrey, UK