Elucidating the role of IRF4 in reprogramming the tumor microenvironment in follicular lymphoma

PROJECT SUMMARY/ABSTRACT Despite a characteristic indolent course, a substantial subset of follicular lymphoma (FL) patients has an early relapse with a poor outcome. Thus far, efforts to identify factors that predict survival have been unsuccessful. However, we and others have demonstrated the prognostic relevance of the tumor microenvironment (TME) in FL and provided initial evidence for the role of specific genetic alterations in shaping different environments with highly dissimilar clinical courses. Yet, the crosstalk between malignant B cells and other immune cells of the TME is poorly understood, as is the role of molecular alterations in modulating this interplay. This underscores the urgent need to improve our understanding of how tumor-immune interactions may drive lymphomagenesis and represent therapeutic vulnerabilities. Through massive genetic and transcriptomic sequencing, we found that FL patients with increased expression of IRF4, an NF-kB target with a critical role in B cell differentiation, display dysregulated immune signatures and an immunosuppressive TME with a poor prognosis. We hypothesize that increased IRF4 expression disrupts the immune synapse between B cells and T follicular helper (TFH) cells while promoting suppressive T follicular regulatory (TFR) cells, in part by preventing induction of selection molecules such as CD40 and PDL1, and in part by rewiring cytokines release. To test our hypothesis, we propose three specific aims. In Aim 1, we will use novel transgenic mouse models with overexpression and deletion of irf4 to investigate whether and how IRF4 controls tumor immunity in normal and malignant B cells by integrating single-cell transcriptional and translational (CITE-seq) analysis. In Aim 2, we will use high dimensional cytometry (CyTOF), spatially resolved proteomics (CODEX), and CITE-seq in the same mouse models to define the effect of B cells with different IRF4 status on TFH cells. In Aim 3, we will use single-cell transcriptomic and proteomic tools to elucidate the role of TFR cells in response to B cells differently expressing IRF4. The findings of all aims will be validated in human FL samples. Building on her substantial prior laboratory and clinical experience in B cell lymphoma, Dr. Patrizia Mondello will lead these studies under the dual mentorship of Dr. Stephen Ansell, a leader in immunotherapy and TME in lymphoma at Mayo Clinic, and Dr. Laura Pasqualucci, a world expert in the genetics and epigenetics of B cell lymphoma at Columbia University. Mayo Clinic offers an exceptional environment for cultivating a developing career in translational cancer research. To achieve the long-term goal of becoming a successful independent investigator, Dr. Mondello has developed a structured curriculum of activities aimed at broadening her knowledge base, expanding her technical repertoire, and developing leadership skills. She has also assembled an advisory committee of leading scientists. In completing her proposed plan with this team, Dr. Mondello will be prepared to compete for R01 funding and to launch a translational research program studying the dysregulation and therapeutic targeting of chromatin modifiers and transcription factors and their effect on the TME in lymphoma.