Phase I dose escalation and single-stage expansion trial for olaparib, given to 50 patients (including 41 BRCA1 and 7 BRCA2 carriers) with advanced ovarian cancer, previously treated by platinum based therapy. OR in 20 (40%) and SD in 3 (6%) patients. Median duration of response = 28 weeks. Strong correlation with platinum sensitivity of the disease. The gene discussed is BRCA2; the disease is ovarian carcinoma.