San Diego, CA – August 1, 2013 – Sorrento Therapeutics, Inc. (OTCQB: SRNE; Sorrento) announced today that it has filed a Certificate of Amendment to its Restated Certificate of Incorporation to effect a 1-for-25 reverse stock split of its common stock, effective on July 30, 2013. The proposal to effect a reverse stock split was approved by the Company`s stockholders at its Special Meeting of Stockholders held on April 26, 2013, and the specific 1-for-25 ratio was subsequently approved by the Company`s Board of Directors.

At the effective time of the reverse stock split, every twenty five shares of the Company`s issued and outstanding common stock will be automatically converted into one issued and outstanding share of common stock, without any change in par value per share. The reverse stock split will affect all shares of the Company`s common stock outstanding immediately prior to the effective time of the reverse stock split, as well as the number of shares of common stock available for issuance under the Company`s equity incentive plans. In addition, the reverse stock split will effect a reduction in the number of shares of common stock issuable upon the exercise of stock options or warrants outstanding immediately prior to the effectiveness of the reverse stock split. No fractional shares will be issued as a result of the reverse stock split. The Company`s common stock will begin trading on the OTC QB on a split-adjusted basis when the market opens on Thursday, August 1, 2013. The new CUSIP number for the Company`s common stock following the reverse stock split is 83587F 202.

The reverse stock split will reduce the number of shares of common stock issued and outstanding from approximately 336.4 million to approximately 13.5 million.

Computershare Trust Company, N.A. is acting as exchange agent and transfer agent for the reverse stock split. Computershare will provide instructions to stockholders regarding the process for exchanging their pre-split stock certificates for post-split stock certificates. Additional information regarding the reverse stock split can be found in the Company`s definitive proxy statement filed with the Securities and Exchange Commission on April 16, 2013.