XL184: Interim Phase Ib/II data

Interim data from 54 patients in the Phase Ib stage of an ongoing Phase Ib/II trial showed that a maximum tolerated dose (MTD) for the combination of XL184/ Tarceva erlotinib was 50 mg/150 mg. Another preliminary MTD was 125 mg/50 mg. In 44 patients with at least 1 post-baseline scan, XL184 plus Tarceva produced tumor shrinkage in 34 patients. In 53 patients evaluable for response, combination therapy produced partial responses (PR) in 4 patients.

Exelixis said XL184 showed clinical activity in patients who were refractory to Tarceva, a small molecule inhibitor of epidermal growth factor receptor (EGFR). Specifically, combination therapy produced stable disease in 7 out of 9 patients with an EGFR T790M mutation and a PR in 1 patient with an EGFR L858R mutation and c-Met copy number gain. Data were presented at the American Society of Clinical Oncology meeting in Chicago. ...