AUTHOR=Beelen Nicky A. , Aberle Merel R. , Bruno Virginia , Olde Damink Steven W. M. , Bos Gerard M. J. , Rensen Sander S. , Wieten Lotte 

TITLE=Antibody-dependent cellular cytotoxicity-inducing antibodies enhance the natural killer cell anti-cancer response against patient-derived pancreatic cancer organoids

JOURNAL=Frontiers in Immunology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1133796

DOI=10.3389/fimmu.2023.1133796

ISSN=1664-3224

ABSTRACT=Pancreatic cancer is associated with poor prognosis, and limited treatment options are available for the majority of patients. Natural killer (NK) cells in combination with antibodies inducing antibody-dependent cell-mediated cytotoxicity (ADCC) could be a highly effective new therapeutic option in pancreatic cancer. Accurate predictive preclinical models are needed to develop successful NK cell immunotherapy. Tumor organoids, in vitro 3D organ-like structures that retain important pathophysiological characteristics of the in vivo tumor, may provide such a model. In the current study, we assessed the cytotoxic potential of adoptive NK cells against human pancreatic cancer organoids. We hypothesized that NK cell anti-tumor responses could be enhanced by including ADCC-triggering antibodies. We performed cytotoxicity assays with healthy donor-derived IL-2-activated NK cells and pancreatic cancer organoids from four patients. A 3D cytotoxicity assay using live-cell-imaging was developed and enabled real-time assessment of the response. We show that NK cells migrate to and target pancreatic cancer organoids, resulting in an increased organoid death at the 5:1 effector-to-target cell (E:T) ratio, compared to the no NK cell controls (average fold change from baseline of 2.2±0.9 vs 1.4±0.6). After 24-hours of co-culture, the apoptotic signal within organoids plateaued, after which organoid 2D growth increased. Organoids from 2 out of 4 patients were sensitive to NK cells while organoids from the other two patients were relatively resistant, indicating patient-specific heterogeneity among organoid cultures. The ADCC-inducing antibodies avelumab (anti-PD-L1) and trastuzumab (anti-HER2) increased NK cell-induced organoid cell death, which was highest at the 5:1 E:T-ratios (average fold change from baseline of 3.5±1.0 and 4.5±1.8, respectively). Moreover, combination therapy with avelumab and trastuzumab resulted in complete disintegration of organoids. Finally, inclusion of ADCC-inducing antibodies was able to overcome resistance in NK-organoid combinations with low or no kill. These results support the use of organoids as a relevant and personalized model to study the anti-tumor response of NK cells in vitro and the potential of ADCC-inducing antibodies to enhance NK cell effector function.