Johnson & Johnson's Zytiga (abiraterone acetate) is set to earn peak-year sales of $910 million in major world markets from its use in the treatment of metastatic castrate-resistant prostate cancer (MCRPC), according to new forecasts.

Early last month, Zytiga was approved by the US Food and Drug Administration (FDA) after priority review as an oral, once-daily medication for use in combination with prednisone for the treatment of patients with MCRPC who have received prior chemotherapy containing docetaxel.

Following its US introduction, Zytiga is also expected to launch in the same setting later this year in Europe, according to research firm Decision Resources, which is expecting the drug to reach peak annual sales totaling $910 million in the US, France, Germany, Italy, Spain, the UK and Japan.

In a pivotal Phase III (COU-AA-302) trial, Zytiga demonstrated a survival improvement when used in combination with prednisone (3.9 months) as compared with placebo plus prednisone.

"With labelling for Zytiga as expected and mirroring the Phase III trial population, Zytiga will be positioned to compete with Sanofi's cytotoxic agent Jevtana [cabazitaxel], which launched in July 2010, also for MCRPC patients who had received prior docetaxel-containing chemotherapy," comments Rachel Webster, an analyst at Decision Resources.

"Zytiga's survival benefit, coupled with its favourable safety and tolerability profile and familiar mechanism of action, will ensure that this orally-available agent will experience robust uptake through 2019," she forecasts.

The firm also reports that Zytiga's main competition in the first-line asymptomatic and minimally symptomatic setting - in which a Phase III trial is current ongoing - will be Dendreon's Provenge (sipuleucel-T) and, to a lesser extent, Active Biotech/Ipsen's tasquinimod.

In the second- and third-line settings, Zytiga will compete primarily with Jevtana and, to a lesser extent, with Takeda's TAK-700, according to the report, which notes that both tasquinimod and TAK-700 are presently in Phase III clinical trials in the US, while Provenge and Jevtana are currently available for the treatment of MCRPC.