For the second time this month, Dr. Patrick Soon-Shiong, a biomedical entrepreneur Forbes says is worth $13 billion, has invested in a San Diego biotech company.

Soon-Shiong, founder and CEO of NantWorks LLC, said Wednesday that he has agreed to put $48 million into Conkwest Inc., a developer of a cell-based cancer therapy. The company is also getting $2 million from fellow San Diego-based biotech Sorrento Therapeutics Inc., for a total of $50 million.

Earlier in December, Sorrento Therapeutics announced a $42 million investment from Soon-Shiong.

All the investments are in the form of stock purchases.

"The collaborations between NantWorks and Sorrento and between Sorrento and Conkwest offer access to state-of-the-art technologies, capabilities and expertise that are synergistic and will enable the accelerated development of many potent and novel cancer immunotherapies," Soon-Shiong said. "We look forward to contributing to this close and supportive collaboration with the shared goal of providing much-needed treatments for patients suffering from malignant disorders with significant unmet need."