Directors of Response Genetics Inc. have appointed Thomas A. Bologna as chief executive and they elected him chairman.

The Los Angeles developer of diagnostic tests for cancer on Thursday said Bologna replaced Denise McNairn as of Wednesday. McNairn had been serving as interim chief executive since July 22, when founder Kathleen Danenberg stepped down to focus on her role as scientific and technology officer.

Former Chairman Kirk K. Calhoun will remain on the board, and was elected to the newly created position of lead director. McNairn will continue to serve as the company’s vice president, general counsel and secretary.

Bologna since 2006 had been chief executive at Orchid Cellmark Inc., a publicly held Dayton, Ohio provider of DNA identity testing. Prior to that, he was chief executive of venture-backed Carlsbad biotech Quorex Pharmaceuticals Inc., where he orchestrated its sale to Pfizer Inc.

“He is the ideal leader for Response Genetics as we seek to accelerate the sales and growth of our existing product lines, achieve new research breakthroughs and improve our financial performance,” said Calhoun in a statement.

Shares were down 6 cents, or 4.6 percent, to $1.25 in midday trading on the Nasdaq.