March 12 (Reuters) - Pfizer Inc's Prevnar 13 vaccine, designed to protect against pneumonia, performed well in a large-scale trial among elderly patients, boosting the chances of strong sales of the blockbuster product, analysts said.
The trial, whose results were announced on Wednesday, cut by 46 percent initial episodes of pneumonia acquired outside of hospitals from infection with a common family of bacteria.
The study also showed that adults aged 65 and older who were immunized with the vaccine were 75 percent less likely, compared with patients taking placebos, to develop "invasive" infections in the bloodstream with Streptococcus pneumoniae bacteria, with or without pneumonia. That secondary goal of the trial was achieved by an impressive margin.
Meeting another secondary goal, there was a 45 percent reduced incidence of first situations in which the pneumonia was caused by the bacteria, but the bacteria were not detected in the bloodstream or any other normally sterile site in the body.
Pfizer last month said Prevnar 13, used mainly to prevent infections with the bacteria in young children, had met primary and secondary goals of the 85,000-patient trial, called CAPiTA. But the largest U.S. drugmaker, at the time, did not provide clinical data from the study, which was conducted in the Netherlands.
Prevnar 13, sold under the brand name Prevenar 13 in many markets outside the United States, is one of Pfizer's biggest products. It and an older version of the vaccine known as Prevnar 7 have combined annual sales of $4.4 billion, making them the company's second-biggest franchise.
J.P. Morgan analyst Chris Schott on Wednesday said he expects $300 million of Prevnar 13 sales in the adult population in 2015, thanks to the "robust" data in the CAPiTA study, growing to $1.5 billion over time.
Alex Arfaei, an analyst with BMO Capital Markets, was far more bullish. He called the results of the trial "positive and better than our expectations" and predicted adult sales of Prevnar 13 would reach $4.1 billion in 2016.
Arfaei, in a research note, predicted especially strong demand among adults outside of the United States in countries where smoking and other factors make people more vulnerable. Infections from the bacteria are often referred to as pneumococcal disease.
Pfizer shares were little changed in morning trading on the New York Stock Exchange.