Sixty patients were evaluated for safety, pharmacokinetics, and tumorresponse as of the May 1, 2008 cutoff; further data also were provided fornine additional patients after the cutoff. Across all tumor types, 10 patientshad partial responses as determined by RECIST criteria: 9 partial responseswere observed in patients with MTC (5 confirmed), and 1 in a patient with aneuroendocrine tumor. An additional 25 patients with various tumor types hadstable disease for at least 3 months, including 8 patients with MTC. Thedisease control rate (percentage of patients with partial responses orprolonged stable disease >3 months) in patients with MTC was 100%, with 53% ofevaluable MTC patients (9 of 17) experiencing partial responses. With a singleexception, all of the evaluated MTC patients had reductions in theMTC-associated plasma markers calcitonin and carcinoembryonic antigen. Most ofthe MTC patients in the trial had previously failed other treatments,including tyrosine kinase inhibitors with anti-RET activity (e.g., vandetanib,sorafenib, motesanib), chemotherapeutics, immunotherapy, radioactive iodine,and radiotherapy.

'Patients with medullary thyroid cancer are a highly underservedpopulation as there is no active approved therapy available at this time.Targeted therapeutics, such as dual inhibitors of RET and VEGFR2, are thefirst compounds showing activity in this disease. The phase 1 results ofXL184, the first such molecule in this class also to inhibit the oncogenic METreceptor, were reported today by Drs. Salgia and Kurzrock, and are remarkable,both in terms of the high frequency of responses and how rapidly they occur,'said Steven I. Sherman, MD, Chair and Professor, Department of EndocrineNeoplasia and Hormonal Disorders, University of Texas M.D. Anderson CancerCenter, Houston, Texas. 'I am looking forward to the phase 3 trial of XL184 inthis indication and believe that studies like this will importantly advancethe care of patients with medullary thyroid cancer.'