The designation is offered only to therapies meant to treat rare diseases — those affecting fewer than 200,000 Americans. It qualifies NantKwest for treatment-development incentives, including tax credits for clinical testing.
The orphan drug application was based on interim data from the ongoing Phase 2 trial (NCT02465957) evaluating aNK therapy in patients with metastatic or locally advanced Merkel cell carcinoma. Many had received several other treatments (including immune checkpoint inhibitors) and had failed to respond, but responded to aNK therapy.
The data was presented by Dr. Shailender Bhatia from the University of Washington, Fred Hutchinson Cancer Research Center in Seattle, at the Annual Society for Immunotherapy of Cancer (SITC) meeting, in November 2016.
“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,” Dr. Patrick Soon-Shiong, chairman and CEO of NantKwest, said in a news release.
“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,” he added.
Natural killer cells, the body’s first line of defense, have the innate ability to rapidly seek and destroy abnormal cells, like cancer cells, without requiring prior exposure or activation by support molecules.
NantKwest’s therapy contains activated NK cells that release toxic granules directly into cancer cells through cell-to-cell contact to induce apoptosis (cell death). The treatment is designed to be administered in an outpatient facility.
Data from prior Phase 1 safety studies conducted in advanced blood cancers and solid tumors have shown encouraging evidence of safety, anti-tumor activity, and prolonged survival.
Interleukin-15 (which stimulates T-cell proliferation and NK cell activation) has been shown to enhance the activity of NK cells, according to recent research. Based on the findings, the study’s protocol was amended to include ALT-803 (a drug that mimics IL-15 activity), which is expected to work together to improve the activity of aNK cells and the patient’s own NK cells.
“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,” said Soon-Shiong. He is encouraged by the anti-tumor activity of this therapy and “look[s] forward to the rapid development of this clinical program,” which may offer benefits to a broad range of cancer diseases.
This Phase 2 trial, taking place in Pennsylvania and Washington, is currently recruiting participants. The study is expected to end in December.