Pfizer Inc.’s blockbuster vaccine, Prevnar 13 (pneumococcal polysaccharide conjugate vaccine [13-valent, adsorbed]), could be poised for a big boost.

The New York-based pharma reported that its postmarketing Community-Acquired Pneumonia Immunization Trial in Adults, or CAPiTA, study evaluating Prevenar 13 – the drug’s name outside the U.S., Canada and Taiwan – met its primary endpoint by demonstrating efficacy against a first episode of vaccine-type community-acquired pneumonia (CAP). The CAPiTA study also met both secondary objectives by showing effectiveness against a first episode of non-bacteremic/non-invasive vaccine-type CAP and a first episode of vaccine-type invasive pneumococcal disease (IPD).

Prevenar 13 was introduced for use in infants and young children in Europe in December 2009. The drug subsequently was approved in more than 120 countries, including the U.S. and Japan, becoming the most widely used pneumococcal conjugate vaccine in the world and Pfizer’s second biggest seller after Lyrica (pregabalin).

In addition, Prevnar/Prevenar 13 – so called for its effect in preventing pneumococcal pneumonia caused by 13 of the most common Streptococcus pneumoniae strains – is approved for adults 50 and older in more than 90 countries and in the U.S. and European Union (EU) for children and adolescents ages 6 to 17. Recently, Prevenar 13 also was approved in the EU for adults 18 to 49 years of age.

The FDA green-lighted Prevnar 13 under accelerated approval to address an unmet medical need in older adults but required Pfizer to conduct the CAPiTA study to confirm the drug’s efficacy in preventing vaccine-type pneumococcal pneumonia. According to Pfizer, the five-year CAPiTA is the largest double-blind, randomized, placebo-controlled vaccine efficacy trial ever conducted in adults, enrolling approximately 85,000 adults 65 and older and involving 58 sentinel hospitals used for surveillance of CAP and IPD.

In the study, conducted at 160 sites in the Netherlands, vaccine-type CAP (VT-CAP) was defined as CAP caused by any S. pneumoniae serotype included in the vaccine. Non-bacteremic/non-invasive VT-CAP was defined as CAP in which vaccine-type S. pneumoniae caused the pneumonia but was not detected concurrently in the bloodstream or any other sterile site. Vaccine-type IPD was defined as a case in which vaccine-type S. pneumoniae was present in the bloodstream or any other sterile site, with or without pneumonia.

“The CAPiTA findings reinforce the important role that immunization with Prevenar 13 may play in reducing the incidence and burden of vaccine-type pneumococcal CAP and IPD among adults aged 65 and older,” Pfizer spokeswoman Sally Beatty told BioWorld Today.

Pfizer said the safety profile of Prevenar 13 observed in CAPiTA was consistent with previous studies conducted in adults, which have shown common side effects of pain, redness, or swelling at the injection site, limitation of arm movement, fatigue, headache, muscle pain, joint pain, decreased appetite, chills or rash.

The company plans to present detailed efficacy and safety results March 12 in a late-breaker session at the 9th International Symposium on Pneumococci and Pneumococcal Diseases in Hyderabad, India.

Pfizer also will meet with regulatory bodies, including the FDA and European Medicines Agency, and with committees that provide recommendations on vaccination regimens to discuss the CAPiTA data and potential label and recommendation updates, according to Beatty.

PREVAR SALES COULD HIT $5 BILLION?

In an email Monday morning following disclosure of the CAPiTA findings, ISI Group analyst Mark Schoenebaum cautioned that Pfizer did not disclose “important exploratory measures, including non-vaccine type CAP and overall mortality,” noting that “major upside potential” for the stock depends on these endpoints.

Still, that potential could be huge. The Prevnar vaccine “family,” which includes an older version known as Prevnar 7, generated 2013 global sales of approximately $4 billion, according to Pfizer data. Schoenebaum called the Street model, which estimated an incremental $1 billion annually for the adult indication, “achievable.” In fact, he argued the add-on to Prevnar could exceed that threshold. Adults 65 and older represent a global market of approximately 140 million, and adults ages 50 to 65 plus high-risk adults ages 18 to 49 could swell the total potential market above 400 million, Schoenebaum pointed out. With 10 percent to 30 percent global penetration across the larger potential market over the course of five years at a steady state – to account for re-vaccinations – he estimated Prevnar/Prevenar could account for $5 billion in annual revenues.

“We think hitting both primary and secondary is positive and ‘checks the box,’” he wrote. In the adult setting, non-invasive pneumonia is more prevalent in the elderly – accounting for some 175,000 hospitalizations in the U.S. – and potentially fatal – roughly 5 percent to 10 percent or more in the developed world, according to Schoenebaum.

Much of the upside depends on whether vaccine candidates moving through the clinic prove their mettle against CAP. Although big pharmas are the biggest players in the pneumococcal vaccine space, at least one biotech is trying to muscle in. Genocea Biosciences Inc. is conducting a phase I study of GEN-004 in S. pneumoniae, seeking to become the first vaccine to block infections caused by all pneumococcus strains. Recent scientific findings suggest Th17 responses make up a natural mechanism to clear pneumococcus from the nasopharynx, and GEN-004 contains three protein antigens – SP0148, SP1912 and SP2108 – that Genocea proved to have an association with Th17 activity.

Shares of Genocea (NASDAQ:GNCA), which began trading earlier this month following an initial public offering, gained 49 cents Monday to close at $12.54.

Pfizer shares (NYSE:PFE) gained 53 cents, closing at $31.99.

Separately, Pfizer reported Monday that the FDA approved a supplemental new drug application updating the label of Xeljanz (tofacitinib citrate) to include radiographic data from two phase III studies: ORAL Scan (A3921044) at six months and ORAL Start (A3921069) at six and 12 months. The studies evaluated the effect of the oral JAK inhibitor, designed to treat moderately to severely active rheumatoid arthritis, on the progression of structural joint damage.