Two experimental AstraZeneca drugs show promise in ovarian cancer

May 31 (Reuters) - A combination of two drugs developed by AstraZeneca Plc (NYSE: AZN - news) , olaparib and cediranib, was shown in a mid-stage study to nearly double the length of time certain ovarian cancer patients lived without their disease getting worse.

After spurning a $118 billion takeover approach from Pfizer (TLO: PF-U.TI - news) Inc, Britain's AstraZeneca is aiming to show investors at this weekend's meeting of the American Society of Clinical Oncology in Chicago that its pipeline of cancer drugs offers an opportunity for future sales growth.

The 90-patient study is the first to look at a drug that blocks a cell repair enzyme known as PARP, olaparib, together with a drug designed to prevent the formation of blood vessels needed by tumors, cediranib, for treating ovarian cancer.

It demonstrated progression-free survival of 17.7 months with the combination treatment, compared with 9 months for olaparib alone. Patients in the trial had recurrent cancer that had initially responded to treatment with platinum-based chemotherapy or had cancer related to the BRCA gene.

Side effects, including high blood pressure, fatigue and diarrhea, occurred more frequently in patients treated with the combination therapy.

Researchers said past trials of standard chemotherapy in the same patient population have shown progression-free survival of between eight and 13 months.

Platinum-based chemotherapy is one of the main treatments used for ovarian cancer. However, it can make patients very sick and typically loses effectiveness over time.

"The significant activity that we saw with the combination suggests that this could potentially be an effective alternative to standard chemotherapy," Dr Joyce Liu, the study's lead author and an oncologist at Dana-Farber Cancer Institute in Boston, said in a statement.

AstraZeneca has projected that sales of olaparib could reach $2 billion a year, but Wall Street estimates are lower. Leerink forecast sales of the drug at $900 million in 2026. (Reporting By Deena Beasley; Editing by David Gregorio)