NantKwest, 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 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.

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."