An Interleukin-15 Superagonist Enables Antitumor Efficacy of Natural Killer Cells Against All Molecular Variants of SCLC

Introduction: SCLC is a highly aggressive tumor with a 5-year survival rate of less than 6%. A heterogeneous disease, SCLC is classified into four subtypes that include tumors with neuroendocrine and non-neuroendocrine fea-tures. Immune checkpoint blockade has been recently added for the frontline treatment of SCLC; however, this therapy has only led to modest clinical improvements. The lack of clinical benefit in a cancer type known to have a high tumor mutational burden has been attributed to poor T-cell infiltration and low expression of MHC-class I in most SCLC tumors. In an attempt to devise a more effective immuno-therapeutic regimen, this study investigated an alternate approach on the basis of the use of the clinical-stage interleukin-15 superagonist, N-803.Methods: Preclinical models of SCLC spanning all molec-ular subtypes were used to evaluate the susceptibility of SCLC to natural killer (NK)-mediated lysis in vitro, including NK cells activated by N-803. Antitumor activity of N-803 was evaluated in vivo with a xenograft model of SCLC.Results: In vitro and in vivo data revealed differences in susceptibility of SCLC subtypes to lysis by NK cells and that NK cells activated by N-803 effectively lyse SCLC tumor cells across all variant subtypes, regardless of their expression of MHC-class I.Conclusions: These findings highlight the potential of a novel immune-based intervention using a cytokine-based therapeutic option for the treatment of SCLC. We hypothe-size that N-803 may provide benefit to most patients with SCLC, including those with immunologically cold tumors lacking MHC expression.Published by Elsevier Inc. on behalf of International Asso-ciation for the Study of Lung Cancer. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).