Abstract 3853: T cell ferroptosis attenuates antitumor immune responses in sickle cell disease
Authors: Zhao Zilong , Hu Benxia , Deng Yalan , Soeung Melinda , Genovese Giannicola , Li Wenbo , Msaouel Pavlos , Yang Liuqing , Lin Chunru 
Published: March 2024

Abstract
Background: Sickle cell disease (SCD) is the most common inherited blood disorder and arises from homozygosity for the HbS mutation (GAG&gt;GTG: βGlu6Val) leading to the production of abnormal hemoglobin that cause sickle shaped red blood cells (RBCs). Individuals with SCD are at higher risk than the general population for developing hematologic malignancies or solid tumors such as renal medullary carcinoma (RMC). Although relatively rare, RMC is one of the most aggressive kidney cancers and is the third most common kidney cancer among children and young adults who harbor sickle hemoglobinopathies such as SCD or sickle cell trait (SCT) which occurs due to heterozygosity for the HbS mutation. Molecular profiling studies have shown that most cases involve biallelic inactivation of the SMARCB1 gene, either through simultaneous hemizygous loss and translocation or by homozygous loss. The loss of SMARCB1 and subsequent dysregulation of chromatin remodeling are key factors contributing to the development and progression of renal medullary carcinoma. Despite manifesting an inflamed tumor immune microenvironment, RMC consistently demonstrates resistance to conventional immune checkpoint inhibitors (ICI). Ameliorating the efficacy of immunotherapy of RMC is vital for research and potential therapeutic interventions by targeting CD8+ T cells.
Methods: CyTOF was performed by using the spleen of WT mice and SCD mouse model. mRNA was isolated from CD8+ T cells of Peripheral Blood Mononuclear Cell (PBMC) collected from healthy donors and SCD patients followed by bulk RNA sequencing. Hi-C was conducted using CD8+ T cells isolated from PBMC of healthy donors and SCD patients. We employed DNA FISH (Fluorescence in Situ Hybridization) to examine alterations in gene architecture within CD8+ T cells under varying conditions.
Results: RMC tumors exhibit accelerated tumor growth and reduced numbers of tumor resident CD8+ T cells in SCD mice model compared with WT control. CD8+ T cells in the SCD associated tumor microenvironment (TME) are subjected to ferroptosis by downregulation of SLC7A11; however, SMARCB1 loss promotes the resistance of RMC tumor cells to ferroptosis. Genomic architecture of CD8+ T cells is altered under SCD conditions, potentially contributing to immune dysfunction.
Conclusions: Our research has identified significant alterations in the 3D genome architecture of CD8+ T cells in individuals with SCD. These alterations lead to transcriptional inhibition of SLC7A11, resulting in CD8+ T cell ferroptosis and a hindered anti-tumor immune response in RMC. These findings elucidate the mechanistic relationship of SCD with ICI resistance in cancers such as RMC and provide novel avenues for therapeutically sensitizing tumors to immunotherapies in individuals with SCD.
Keywords: Sickle Cell Disease, Renal Medullary Carcinoma, SMARCB1, Ferroptosis, Genomic Architecture Alteration, Hi-C, SLC7A11
Citation Format: Zilong Zhao, Benxia Hu, Yalan Deng, Melinda Soeung, Giannicola Genovese, Wenbo Li, Pavlos Msaouel, Liuqing Yang, Chunru Lin. T cell ferroptosis attenuates antitumor immune responses in sickle cell disease [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3853.