Response Genetics Inc. said its fourth quarter revenue fell 23 percent with the end of a study for a large pharmaceutical client, leading to a larger net loss.

The Los Angeles developer of genetic diagnostic test kits on Tuesday reported a net loss of $3.9 million (-20 cents a share) for the quarter ended Dec. 31, compared with a net loss of $1.1 million (-6 cents) in the same period a year earlier.

Revenue fell from $6.4 million to $4.9 million, which the company attributed to nearly completed clinical trials related to an experimental GlaxoSmithKline product. Revenue from pharmaceutical clients totaled $1.8 million, while revenue from the company’s larger ResponseDx genetic test unit was up “slightly” to $3.1 million.

Chief Executive Thomas Bologna, who joined the company in December, said the company plans to more aggressively pursue new collaborations with pharmaceutical clients through its services business.

“Our primary near-term priorities are to build out the management team, implement several operational enhancements, expand our sales force, strengthen our marketing and back-office capabilities and focus on growing our suite of ResponseDX products,” Bologna said in a statement.

Shares fell 19 cents, or 9 percent, to $1.86 on the Nasdaq.