Abstract PR009: Functional inhibition of natural killer cells enables surgery-induced accelerated neuroblastoma tumor growth in a mouse model

Abstract Surgery is a cornerstone of induction therapy in high-risk neuroblastoma (HR-NBL). Local relapse is decreased by gross total resection, however metastatic relapse is unaffected by extent of surgery. Whether and how surgery may be impacting pre-existing distant metastatic disease in HR-NBL remains unknown. We added surgery to an established mouse model of HR-NBL to test the hypothesis that surgery-induced immune dysregulation functions as a pro-tumoral stimulus. MYCN-amplified 9464D murine neuroblastoma cells derived from the Th-MYCN mouse model are syngeneic to immune competent wild-type C57BL/6J mice and are implanted in the flank dermis. Non-excisional abdominal surgery is performed on six-week-old female and male tumor-bearing mice to model the host response to surgical stress on pre-existing distant metastatic disease. Mice are induced with 2-3% inhaled isoflurane and given 1.5 mg/kg buprenorphine-ER for pain control. Abdominal surgery includes a midline incision, exposure of the peritoneal cavity, externalization of the intestines, and forceps crush of the liver edge to model fluid losses, temperature dysregulation, and the collateral tissue damage typically encountered during surgery for complex neuroblastoma tumor removal. Control mice remain in their home cage following tumor cell inoculation. Surgery exposure accelerates tumor growth at 2 weeks (tumor volume: surgery, 92.8±21.4 mm3 vs. control, 46.5±12.0 mm3; N. = 10/group, p < 0.0001) and at 4 weeks (tumor volume: surgery, 303.3±81.6 mm3 vs. control, 161.2±101.8 mm3; N. = 10/group, p = 0.003). Depletion of natural killer (NK) cells using anti-NK1.1 antibody eliminates the surgery-induced accelerated tumor growth (tumor volume at 2 weeks: surgery, 68.0±15.7 mm3 vs. control, 73.1±19.5 mm3; N. = 10/group, p = 0.538; 4 weeks: surgery, 260.9±119.4 mm3 vs. control, 290.5±150.2 mm3; N. = 10/group, p = 0.639). CD107a is a cell surface marker involved in cytotoxic granule release on NK cells, and the fraction of cells expressing this marker as assessed by flow cytometry is reduced by 62% after surgery exposure in wild-type mice (surgery, 1.74±0.56% vs. control, 4.57±0.72%; % of NK1.1+ cells; p < 0.0001). Interestingly, the total number of NK cells were not different in either spleen (surgery, 3.68±0.19% vs. control, 3.51±0.25%; % of CD3- cells; p = 0.08) or tumor-draining lymph nodes (surgery, 1.14±0.22% vs. control, 1.31±0.28%; % of CD3- cells; p = 0.10) after surgery exposure in wild-type mice. From these data we conclude that the host response to surgery exposure accelerates distant tumor growth in a translationally relevant pre-clinical mouse model of HR-NBL and is at least partially mediated via surgery-induced inhibition of antitumor NK cell function. Citation Format: Chenkai Mao, Michael B. Dwinell, Donna McAllister, Maria Poimenidou, Brian T. Craig. Functional inhibition of natural killer cells enables surgery-induced accelerated neuroblastoma tumor growth in a mouse model [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl):Abstract nr PR009.