San Diego- and Pennington, New Jersey-based OncoSec Medical said late Thursday that the company's CEO, Daniel O'Connor, has resigned. The company has appointed Brian Leuthner as the company's Interim CEO. Leuthner was previously Chief Operating Officer at the company. The reason for the sudden resignation were not given. OncoSec said former CEO O'Connor also is stepping down from his seat on the company's board of directors. OncoSec is a developer of cancer immunotherapies, with its lead compound aimed at treating metastatic melanoma patients.