Reduced Human Leukocyte Antigen Expression in Rhabdomyosarcoma: Implications for Immune Recognition
The most common pediatric soft tissue tumor is Rhabdomyosarcoma (RMS) which arises mainly from skeletal muscle. Despite an aggressive treatment approach which incorporates chemotherapy, radiation therapy and surgery, it is associated with poor survival, especially in high-risk patients or those with recurrent disease. Unfortunately, there have been no recent significant advances in RMS treatment, therefore, there is a need for novel therapeutic approaches especially in high-risk patients. Recently, immunotherapies which re-engage the body’s immune system to fight cancer have been shown to be promising in multiple cancers but limited in RMS due to immune evasion mechanisms including low human leukocyte antigen (HLA) class I molecules. These molecules are critical for immune recognition as they display tumor specific proteins on the surface of the cancer cell, which are identified and attacked by the immune system, namely by cytotoxic lymphocytes (CTLs). The aim of this proposal is to elucidate the mechanism of HLA class I loss in RMS and develop strategies to restore its expression so it’s better targetable by the immune system and immunotherapies.
Objective 1 focuses on identifying and validating genetic regulators of HLA class I expression in an RMS cell line using the gene editing tool, CRISPR/cas9. Genes identified will be validated by knocking them out in the cells which are cultured with lymphocytes to assess the HLA class I expression and immune cell activation. This will be followed by testing in a mouse model.
Objective 2 aims to characterize transcriptional programs regulating HLA expression and their influence on immune cell function and tumor immune evasion in RMS. Differential expression analysis will compare tumors with high and low HLA expression, identifying pathways influencing HLA expression. We will explore the immune infiltration in correlation with HLA expression to reveal how immune evasion is driven by altered HLA dynamics.
This proposal is significant because it addresses a critical barrier to immunotherapy in RMS. By restoring HLA class I expression, this study will enhance T-cell-mediated immunity and guide future clinical trials. The project is innovative in its use of CRISPR/cas9 screening to identify regulators of immune escape and immune profiling in an RMS cohort to understand tumor-immune interactions. Ultimately, this work aims to pave the way for more effective, targeted immunotherapies, that will improve survival in RMS.