Abstract 2741: Sexual dimorphism induces differential immunomodulatory outcomes from local nanoparticle and focused ultrasound therapy in murine model of head and neck cancer
Authors: Chandrasekar Sri Vidhya , Singh Akansha , Ranjan Ashish 
Published: June 2023

Abstract
Nanoparticles (NPs) and therapeutic devices are increasingly being investigated to re-engineer poorly immunogenic tumors into activated ′hot′ targets. Innate & adaptive immunological responses in females are known to be relatively superior to males. However, the development of NPs and therapeutic devices generally lacks attention to the impact of sex on therapeutic outcomes. Herein, we evaluated the role of sexual dimorphism in the immune-mediated remission of murine head & neck (MOC2) tumors following in-situ therapy with immunogenic cell death-enhancing calreticulin nanoparticle (CRT-NP) and focused ultrasound-based histotripsy (HT). CRT-NP was synthesized with DOTAP and cholesterol lipids using the thin film and extrusion methodology and loaded with a full-length clone CRT-expressing vector. CRT-NP was characterized for size and Ζ potential (ZP) using dynamic light scattering. To assess in vivo efficacy, male & female mice bearing MOC2 tumor xenografts were randomized into the following groups (n=6mice/group)¦ 1) Control, 2) CRT-NP, & 3) HT. Three intratumoral CRT-NP injections (20µg CRT-DNA/injection) were given 2 days apart 7-days post-inoculation. For comparing gender-mediated tumor immunomodulation, two local HT treatments were similarly administered in male & female MOC2 cohorts. Mice were sacrificed on day 20-post inoculation & the tumors, tumor-draining lymph nodes, spleen, & serum were processed for assessing inflammatory signatures using flow cytometry, & cytokine analysis. CRT-NPs demonstrated a hydrodynamic diameter of ≈260nm, ΖP of +17mv & a PDI ≤0.3. Compared to the untreated controls that showed a pronounced increase in tumor volumes, male & female mice treated with CRT-NP showed a ≈65% reduction in tumor growth post-treatment. HT treatment of female mice similarly suppressed the MOC2 tumor growth rates ≈64% vs. corresponding untreated control, however, it was ineffective in inducing remission of male mice tumors. The reduced HT efficacy in male mice correlated with increased infiltration of immunosuppressive NK+PD1+ cells & CD11b+PDL1+ macrophage in tumors. In contrast, the improved efficacy in female mice with both CRT and HT treatments associated with increased infiltration of CD4+ cells, CD8+ cells, NK cells, macrophage (CD11b+CD86+MHCII+), & a reduction in the M-MDSC population in the treated tumors. An additional correlation of local immune cell immunomodulation with systemic serum cytokine responses is currently in the works. CRT-NP was effective in both male & female mice. HT-induced tumor remission in females, but male mice demonstrate immunoresistance. These suggest that immunomodulatory therapies should account for sexual dimorphism as a variable. A higher accumulation of immunosuppressive cells in male TME can impact the anti-tumor immunity of immunomodulatory therapies in preclinical and clinical settings.
Citation Format: Sri Vidhya Chandrasekar, Akansha Singh, Ashish Ranjan. Sexual dimorphism induces differential immunomodulatory outcomes from local nanoparticle and focused ultrasound therapy in murine model of head and neck cancer [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 2741.