Nicotinamide-Enhanced NK Cell Expansion: A Clinical Approach for Improved In Vivo Persistence and Proliferation

A novel culture technique has been developed to enhance the effectiveness of cytolytic Natural Killer (NK) cells for treating various malignancies. This method expands donor NK cells, which are crucial for clinical applications. Vitamin B-3, or Nicotinamide (NAM), plays a significant role in cell functions such as adhesion, migration, and differentiation. Our research has shown that NAM can boost NK cells' tumor-killing ability and their secretion of key cytokines like TNFα and IFN-γ. NK cells expanded with NAM exhibit typical activation changes without altering the balance of their receptors, and NAM reduces the upregulation of CD200R and PD-1, which may protect them from immune evasion by cancer.

In terms of in vivo performance, NAM-cultured NK cells have demonstrated superior retention and proliferation in mice models, supported by an increase in CD62L expression, which is essential for NK cell trafficking and proliferation. A clinical-grade culture process has been established using apheresis units from healthy donors, with T cells removed and the remaining fraction cultured in a closed system with IL-15 and NAM. The use of IL-15 over IL-2 resulted in fewer contaminating cells. Optimal NAM concentration was determined to be 5mM, leading to a substantial expansion of NK cells.

The optimized culture protocol resulted in a median 50-fold expansion of NK cells, with an additional boost from medium supplementation. A single feeding during the culture period was most beneficial for cell expansion and retention. Based on these promising results, a clinical trial is underway at the University of Minnesota to evaluate the safety and efficacy of the NAM-expanded NK cell product in patients with specific types of cancer.