Abstract 2338: Age associated tumor microenvironment induces differential outcomes from immunomodulatory nanoparticles and therapeutic ultrasound in murine melanoma
Authors: Singh Akansha , Oliveira Jessica Fa , Fiering Steven , Butcher Josh , Steinmetz Nicole F. , Ranjan Ashish 
Published: April 2023

Abstract
In-situ vaccination (ISV) of tumors can disrupt their local immunosuppression to aid anti-tumor immunity. These are promising advancements, but little is known about how ISV outcomes are impacted by age-associated tumor microenvironment (TME). Herein, we compared antitumor immunity of two types of ISV-based NPs, Cowpea mosaic virus (CPMV) and calreticulin NP (CRT-NP), and ultrasound-induced histotripsy (HT) in young and aged mice bearing poorly immunogenic B16F10 melanoma tumors. Our comparative immunotherapy studies provide crucial insights into ISV-based local immune priming mechanisms and their translation for geriatric cancer therapy.
We first profiled the immune phenotypes of old (18 mo) vs. young (8 wk) C57BL6 mice bearing bilateral B16F10 melanoma in the flank regions. We then performed ISV of one of the tumor in old and young mice with mechanistically and immunologically different in-situ agents (CPMV, CRT-NP, & HT). Endpoints included assessment of local and abscopal tumor growth 2wks post-treatment. Additionally, the age-associated tumor immunology of treated tumors was determined using transcriptomics analysis, analysis of serum cytokines/chemokines, and profiling of immune cells using flow cytometry.
The primary and secondary (abscopal) B16F10 tumors showed similar or faster growth rates in old than in young mice. Tumorigenesis in aged mice correlated with metastasis-driving serum cytokine levels (CXCL1, CCL11 & MCP-1), and increased expression of immune checkpoint PD1 on T-cells, and TIM3 on NK cells. All three immunotherapies, significantly delayed tumor growth of primary treated tumors in young mice. Compared to CRT-NP and HT, CPMV was relatively less effective in controlling the growth of contralateral secondary untreated tumors in young mice. In contrast, CPMV treatment induced relatively superior remission of treated and untreated tumor sites in aged mice versus CRT-NP and HT. Treatment outcomes correlated with a decrease of pro-tumoral cytokine levels (IL6, IL10 & IL1b) in CPMV-NP-treated old mice. In contrast, young TME showed enhanced T cell exhaustion and populations of splenic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) with CPMV. Alternatively, the presence of immunosuppressive tumor-associated macrophages in older mice reduced outcomes of CRT-NP and HT. Differential gene expression analysis of treated tumors with various in-situ treatments in young and aged mice is currently in the works.
Improving anti-tumor effects of ISVs via increasing the immune function should account for age as a variable since higher accumulation of immunosuppressive cells in aged TME can subvert therapy outcomes. Future studies focused on unique interventions aimed at upregulated targets in TME of old and young mice can shed more light on normalizing outcomes independent of age.
Citation Format: Akansha Singh, Jessica Fa Oliveira, Steven Fiering, Josh Butcher, Nicole F. Steinmetz, Ashish Ranjan. Age associated tumor microenvironment induces differential outcomes from immunomodulatory nanoparticles and therapeutic ultrasound in murine melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2338.