Abstract IA10: Activating innate and adaptive immunity to improve outcome for “cold” tumors

Abstract

Abstract Unlike some adult cancers, most pediatric cancers are considered immunologically cold and generally less responsive to immunotherapy. Anti-GD2 mAb plus cytokine-based immunotherapy has already been incorporated into standard-of-care treatment for pediatric patients with high-risk neuroblastoma achieving remission. However, overall survival remains poor. We are pursuing clinical and preclinical studies to engage innate and adaptive immune responses against immunologically cold tumors. In a recent trial of adjuvant/neoadjuvant anti-GD2 mAb + IL2 (in the form of the hu14.18-IL2 immunocytokine) for advanced resectable melanoma, we evaluated whole-genome transcriptomics (using RNAseq determined immunologic signatures found to be predictive of outcome for patients with neuroblastoma) on resected tumors. The immunologic signatures were highly correlated with overall survival and relapse-free survival for tumors obtained 2 weeks after starting hu14.18-IL2, but not for tumors obtained 2 weeks before starting hu14.18-IL2. In a “functionally cold” mouse melanoma model, we found that radiation and hu14.18-IL2 immunocytokine generate an in situ vaccination-induced adaptive immune response in syngeneic mice bearing large tumors. In contrast, this same approach was not effective in mice bearing a very cold, low-tumor-mutation burden, MYCN driven syngeneic neuroblastoma (9464D-GD2). The addition of checkpoint blockade (IgG2a anti-CTLA-4) was not able to induce tumor eradication. However, the further addition of CpG (as a “danger signal”) and agonist anti-CD40 mAb (as an activator of effector macrophages and of dendritic cells) resulted in tumor-free mice with immune memory. These results suggest that immune activation, with “off the shelf” reagents, may be applicable to the treatment of cold cancers, via innate/adaptive immune engagement. They also suggest that monitoring of intratumoral immune activation could potentially become a useful predictor of which patients will respond to their therapy and which will require additional or alternate therapy. Citation Format: Paul M. Sondel. Activating innate and adaptive immunity to improve outcome for “cold” tumors [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr IA10.