NantCell Inc., a Culver City-based biotech firm founded by Los Angeles billionaire Patrick Soon-Shiong, has raised $30 million in investor funding, according to a Dec. 28 securities filing.

NantCell, a subsidiary of the NantWorks conglomerate controlled by Soon-Shiong, sold $30 million in securities to one investor, according to the filing with the U.S. Securities and Exchange Commission.

The nearly five-year-old firm conducts cell-based research at the molecular level to develop treatments that harness the immune system to fight cancer. The latest funding round follows more than $230 million raised since 2015.

NantCell raised $75 million from one investor in the summer of 2015, ostensibly from Soon-Shiong.

The round was followed by a $100 million equity sale to San Diego-based Sorrento Therapeutics Inc. in exchange for rights to a cancer fighting immunotherapy. Another $57 million was raised in early 2016 in a securities sale to 125 investors.

The company initially paid an undisclosed sum for rights to a failed antibody developed by Amgen Inc. known as ganitumab, which NantCell hoped to redeploy to fight cancer.

In July 2017, NantCell bought $13 million of shares in Cytrx Corp., a biotech firm based in Brentwood, in exchange for the rights to its orphan cancer drug aldoxorubicin, initially developed to treat soft tissue sarcoma.

Health business reporter Dana Bartholomew can be reached at [email protected]. Follow him on Twitter @_DanaBart.