AstraZeneca has started a phase III clinical programme for olaparib, a potential treatment for ovarian cancer.The pharma giant said it had enrolled its first patient for the programme, which is being conducted with the Gynecologic Oncology Group and the SOLO 2 study with the European Network of Gynaecological Oncological Trial Groups.As a result, a pre-tax impairment charge of $285m (£183m) taken in December 2011 will be reversed in the third quarter of 2013. The charge, taken when the company decided not to put olaparib into phase III, will be restored to the balance sheet but will not count in core earnings per share.Antoine Yver, Head of Oncology at AstraZeneca's global medicines development unit, said: "This is a significant milestone for olaparib, and further evidence of AstraZeneca's commitment to invest in distinctive science in our core therapy areas, with a particular focus on high unmet need. "We feel olaparib has real potential to significantly improve treatment decisions for this group of patients who currently have limited options, and to become the next important product in our growing oncology portfolio."SF