Abstract 1712: CAMKV as an immunotherapy target in MYCN-amplified neuroblastoma

Abstract

Abstract Background: Neuroblastoma is an embryonal tumor of the developing sympathetic nervous system that accounts for 10-15% of pediatric cancer-related deaths. Although an intensive treatment regimen consisting of chemotherapy, surgery, radiation, immunotherapy and autologous stem cell transplant is used for patients with high-risk neuroblastoma, about half of these patients ultimately die. Reliable tumor-specific genomic biomarkers, such as MYCN amplification, have been identified for high-risk neuroblastoma and are used to stratify therapy. Recent clinical studies using immunotherapies to target cell surface molecules such as GD2 in neuroblastoma and CD19 in leukemia have shown impressive results, and have highlighted immunotherapy as a critical strategy in combating childhood cancer. Methods: As part of the Stand Up 2 Cancer/St. Baldrick's Pediatric Cancer Dream Team's effort to streamline new immunotherapuetics into the clinic, we developed a computation approach to prioritize new targets for immunotherapy for high-risk neuroblastoma. Here we used MYCN as a biomarker for the most aggressive subset of neuroblastoma to define candidate cell-surface targets that are differentially expressed in MYCN-amplified neuroblastoma. We used RNAi to manipulate gene expression levels of MYCN to determine if these cell-surface targets are under the control of MYCN in neuroblastoma cells. Results: The most significant differentially expressed cell surface molecule in high-risk neuroblastoma based on MYCN-amplification status was the calmodulin kinase-like vesicle-associated gene (CAMKV, p = 1×10-6), which encodes a protein that binds calmodulin in the presence of calcium, but lacks the kinase activity of other calmodulin kinase family members. We have confirmed that CAMKV protein is selectively expressed in MYCN-amplified neuroblastoma cell lines. From membrane fractionation and immunohistochemistry, we have verified that CAMKV is membranous in MYCN-amplified neuroblastoma cell lines and xeongraft tumors. Immunohistochemistry also revealed that CAMKV is not highly expressed in human pediatric normal tissues with the exception of neural tissues. Depletion of MYCN using RNAi resulted in a significant reduction in CAMKV RNA and protein expression (p = 2.3×10-6). Conclusions: These results provide a template for the discovery and validation of immunotherapeutic targets in MYCN-amplified neuroblastoma and have the potential to lead to the development of a new immunotherapy targeting CAMKV. Citation Format: Robyn T. Sussman, Kevin Huang, Pichai Raman, John M. Maris. CAMKV as an immunotherapy target in MYCN-amplified neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1712. doi:10.1158/1538-7445.AM2015-1712