Achillion Pharmaceuticals will celebrate its recent expansion at 300 George St. in New Haven with a ribbon cutting ceremony at 3 p.m. Wednesday.

The 16-year-old Achillion is part of the Connecticut biotech community. In 2015, the company announced a deal with Janssen, the pharmaceutical arm of Johnson & Johnson, to develop next-generation treatments for hepatitis C.

Achillion continues internal research and development of factor D inhibitors, which play an important role in human immune system and may have application in rare diseases and those with broader patient populations.

Achillion grew its employee base by 20 percent last year and is on the same growth trajectory this year.