Amgen is one of 1,900 exhibitors at the BIO International Convention at the Boston Convention and Exhibition Center. It runs through Wednesday.

The Providence Journal / Gretchen Ertl Gretchen Ertl

BOSTON — Pharmaceutical giant Amgen Inc. plans to maintain its manufacturing facility in Rhode Island after the company loses patent protection for the drug Enbrel, two top Amgen officials said in an interview yesterday.

Dennis Fenton, executive vice president, and Joseph Miletich, the senior vice president of research and development, said Amgen expects to produce large quantities of Enbrel for many years, despite heightened competition and the expiration of the drug’s patent protection in 2012.

"Enbrel is a complicated molecule to manufacture," Fenton said during the BIO International Convention in Boston. We don’t expect dramatic market erosion."

If sales of Enbrel dip, he said, the company has developed plans to retrofit its $1-billion plant in West Greenwich to produce other medications.

That is expected to allow the state to retain the 1,700 jobs Amgen has created since it opened the facility in 2002. It could also bolster efforts by state officials to attract other biotech companies, a key goal they cite in attempts to reshape a local economy that has been buffeted by the hemorrhaging of traditional manufacturing jobs.

"We’re looking at other uses for the facility," Fenton said. "It’s been a great site."

Amgen has invested heavily in building and staffing its Rhode Island facility, one of the largest biotechnology manufacturing plants in the world.

But the company’s future uses for the facility have never been publicly discussed, an uncertainty that has come into sharp focus as the extraordinary profits generated by Enbrel have begun to decline.

Growth in sales of Enbrel slowed significantly last year, rising just 12 percent compared with a 35-percent jump in 2005. That trend could intensify in 2012, when rival manufacturers can introduce generic version of the drug.

There are no large-scale, clinical trials of potential other applications for Enbrel, now primarily used for treating rheumatoid arthritis and psoriasis, Miletich said. (He added, however, that small studies by doctors might be under way. “That’s not to say there are not pilot studies,” he said. “I wouldn’t rule out the possibility that we’ll learn more things to use Enbrel for.”)

In Rhode Island, Amgen focuses exclusively on producing Enbrel, a medication that faces intense competition from drugmakers Johnson & Johnson and Abbott. Amgen scientists in West Greenwich have confined their research into methods for increasing the efficiency of Enbrel production, rather than the development of other medications.

All Amgen scientists are encouraged to pursue new research opportunities within the company, a program known internally as the career framework. For Amgen researchers in Rhode Island, however, that transition would require leaving the state.

Amgen, based in Thousand Oaks, Calif., typically operates research facilities in cities where it has acquired biotechnology firms. In Cambridge, Mass., for example, the company hosts research and development activities in a Kendall Square laboratory it built after buying Kinetix Corp. in 1999. Amgen also conducts research in Seattle, where it acquired Immunex, the inventor of Enbrel, in 2002.

But yesterday, Fenton said Amgen’s manufacturing plant in Rhode Island has potential uses beyond the production of a single drug. After investing hundreds of millions of dollars to build the plant and recruit and train scientists, he said, the company has no interest in abandoning the facility.

“We do have a lot of Ph.D.s. It’s not your typical turn-the-crank manufacturing,” Fenton said. “These people are very valuable, so you want them to do something else.”

Fenton also praised the business environment in Rhode Island, saying the company has enjoyed unique access to public officials.

“Governor Schwarzenegger [in California] would not take my call,” he said, “but if I call Governor Carcieri, I’m sure I’d get a call back real quick.”

Fenton and Miletich would not disclose any experimental drugs that might be manufactured in Rhode Island in the future. But they said Amgen has previously altered plants to greatly expand their manufacturing capabilities.

In Boulder, Colo., for example, Amgen transformed a plant designed to produce the drug Kineret into a so-called multi-product launch facility. The plant now produces Denosumab, an experimental drug for treating bone loss; Kepivance, a medicine for oral mucositis; and AMG 53, an experimental medication for stimulating the production of platelets.

“It’s not the facility as much as the people,” Miletich said yesterday.

A similar retrofitting in Rhode Island is likely, Fenton said. But although the transition would preserve high-wage jobs in the state, it is unlikely to significantly grow employment.

Amgen avoids employing more than 2,000 people at a single facility, Fenton said, hoping to limit the potential disruption from a natural disaster. In Rhode Island, he said, fears of hurricanes or the impacts of global warming will constrain further growth.

“You don’t want to put a lot of eggs in one basket,” he said. “It is already a very large site. We’re probably not going to grow larger than we are now.”

bgedan@projo.com