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CULVER CITY, Calif.–Mar. 20, 2017– NantKwest, Inc. (Nasdaq:NK), a pioneering, next generation, clinical-stage immunotherapy company focused on harnessing the unique power of our immune system using natural killer (NK) cells to treat cancer, infectious diseases and inflammatory diseases, announced today that the FDA has granted Orphan Drug Designation to the company’s activated natural killer (aNK) cell therapy for treatment of patients with advanced Merkel cell carcinoma.

NantKwest’s aNK cell therapy is currently in Phase II clinical trials at clinical sites in the United States treating subjects with metastatic or locally advanced Merkel cell carcinoma. This protocol was recently amended to include ALT-803, an IL-15 superagonist therapy that has been shown in preclinical clinical studies to improve the activity of NK cells and will synergistically improve the activity of both NantKwest’s infused aNK cells together with the subject’s own NK cells. The Phase II clinical trial will continue based on this novel drug combination.

The application for Orphan Drug Designation was based in part on data presented at the Annual Society of Immunotherapy (SITC) meeting in November 2016. At the SITC meeting, Dr. Shailender Bhatia from the University of Washington, Fred Hutchinson Cancer Research Center in Seattle, WA presented interim data showing that in a heavily pretreated patient population, many previously having been treated with a number of other therapies including checkpoint inhibitors, aNK natural killer cell therapy demonstrated activity in patients who failed multiple lines of therapy including check point inhibitors.

In commenting on the FDA’s grant of Orphan Drug Designation, Dr. Patrick Soon-Shiong, Chairman and CEO of NantKwest, said: “We believe the FDA’s award of Orphan Drug Designation together with additional data coming out of our ongoing Merkel cell carcinoma Phase II clinical trial will provide us a solid position to submit to the FDA our plans to transition this study to a pivotal study.”

Dr. Soon-Shiong added, “Patients with metastatic or locally advanced Merkel cell carcinoma have an extremely poor prognosis, with less than 20% of patients surviving longer than five years. We are encouraged to see, even in a heavily pretreated patient population, that our aNK natural killer cell therapy has been shown to exhibit encouraging antitumor activity and we look forward to the rapid development of this clinical program as we strive to bring the potential for long-term, durable responses to a broad range of cancer patients in multiple cancer indications.”

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include, among others, statements concerning or implying the timing and conduct of our clinical studies, the anticipated safety and efficacy of our aNK cell therapy and the accomplishment and timing of related regulatory determinations and filings. Forward-looking statements are based on management’s current expectations and are subject to various risks and uncertainties that could cause actual results to differ materially and adversely from those expressed or implied by such forward-looking statements. Accordingly, these forward-looking statements do not constitute guarantees of future performance, and you are cautioned not to place undue reliance on these forward-looking statements. Risks and uncertainties include, but are not limited to, the rate of subject enrollment in our clinical studies; the number of subjects that will need to be enrolled in the trial; difficulty obtaining and maintaining regulatory approvals; our limited experience in conducting clinical studies and significant issues regarding our clinical studies, including, but not limited to, the successful opening and the continued participation of clinical sites and their ongoing adherence to protocols, assumptions regarding enrollment rates, timing and availability of subjects meeting inclusion and exclusion criteria, changes to protocols or regulatory requirements, the ability to comply with and meet applicable laws and regulations, unexpected adverse events or safety issues and the sufficiency of funding and adverse events effecting our ability manufacture and supply cell therapy for our clinical studies. There can be no assurance that data from any of our clinical studies will be sufficient to support an application for marketing in any country or that any such application will ever be approved. These and other risks regarding our business are described in detail in our Securities and Exchange Commission filings, including in our Quarterly Report on Form 10-K for the fiscal year ended December 31, 2016. These forward-looking statements speak only as of the date hereof, and NantKwest, Inc. disclaims any obligation to update these statements except as may be required by law.

About NantKwest

NantKwest (Nasdaq:NK) is a pioneering, next generation, clinical-stage immunotherapy company focused on harnessing the unique power of our immune system using natural killer (NK) cells to treat cancer, infectious diseases and inflammatory diseases. NK cells are the body’s first line of defense due to the innate ability of NK cells to rapidly identify and destroy cells under stress, such as cancer or virally-infected cells.

NantKwest’s unique NK cell-based platform, with the capacity to grow active killer cells as a biological cancer therapy, has been designed to induce cell death against cancer or infected cells by three different modes of action: (1) Direct killing using activated NK cells (aNK) that release toxic granules directly into the cell through cell-to-cell contact, (2) Antibody-mediated killing using haNKs, which are NK cells engineered to incorporate a high affinity receptor that binds to an administered antibody, enhancing the cancer cell killing effect of that antibody, and (3) Targeted activated killing using taNKs, which are NK cells engineered to incorporate chimeric antigen receptors (CARs) to target tumor-specific antigens found on the surface of cancer cells.

Our aNK, haNK and taNK platform addresses certain limitations of T cell therapies, including the reduction of risk of serious “cytokine storms” reported after T cell therapy. As an “off-the-shelf” therapy, NantKwest’s NK cells do not rely on a patient’s own often compromised immune system. In Phase I clinical trials in patients with late stage cancer, NantKwest’s NK cells have been successfully administered as an outpatient infusion therapy without any reported severe side effects, even at doses of 10 billion cells.

By leveraging an integrated and extensive genomics and transcriptomics discovery and development engine, together with a pipeline of multiple, clinical-stage, immuno-oncology programs that include a Phase II trial for a rare form of melanoma and the planned initiation of a clinical trial of NK cells targeted to breast cancer, we believe NantKwest is uniquely positioned to be the premier immunotherapy company and transform medicine by delivering living drugs in a bag and bringing novel NK cell-based therapies to routine clinical care. For more information please visit http://www.nantkwest.com and follow Dr. Soon-Shiong on Twitter@Dr.PatSoonShiong.

Source: NantKwest, Inc.

NantWorks
Jen Hodson, 562-397-3639
jhodson@nantworks.com