BLIMP1 and NR4A3 transcription factors reciprocally regulate antitumor CAR T cell stemness and exhaustion

Abstract

Chimeric antigen receptor (CAR) T cells have not induced meaningful clinical responses in solid tumors. Loss of T cell stemness, poor expansion capacity, and exhaustion during prolonged tumor antigen exposure are major causes of CAR T cell therapeutic resistance. Single-cell RNA-sequencing analysis of CAR T cells from a first-in-human trial in metastatic prostate cancer identified two independently validated cell states associated with antitumor potency or lack of efficacy. Low expression of PRDM1 , encoding the BLIMP1 transcription factor, defined highly potent TCF7 [encoding T cell factor 1 (TCF1)]–expressing CD8 + CAR T cells, whereas enrichment of HAVCR2 [encoding T cell immunoglobulin and mucin-domain containing-3 (TIM-3)]–expressing CD8 + T cells with elevated PRDM1 was associated with poor outcomes. PRDM1 knockout promoted TCF7 -dependent CAR T cell stemness and proliferation, resulting in marginally enhanced leukemia control in mice. However, in the setting of PRDM1 deficiency, a negative epigenetic feedback program of nuclear factor of activated T cells (NFAT)–driven T cell dysfunction was identified. This program was characterized by compensatory up-regulation of NR4A3 and other genes encoding exhaustion-related transcription factors that hampered T cell effector function in solid tumors. Dual knockout of PRDM1 and NR4A3 skewed CAR T cell phenotypes away from TIM-3 + CD8 + and toward TCF1 + CD8 + to counter exhaustion of tumor-infiltrating CAR T cells and improve antitumor responses, effects that were not achieved with PRDM1 and NR4A3 single knockout alone. These data underscore dual targeting of PRDM1 and NR4A3 as a promising approach to advance adoptive cell immuno-oncotherapy.

Establishment and validation of exhausted CD8+ T cell feature as a prognostic model of HCC

“…For example, NR4A and Tox family transcription factors were identified as key mediators of T cell exhaustion’s epigenetic and transcriptional programs ( 31 , 32 ). The hypoxic microenvironment leads to cellular mitochondrial dysfunction, triggering the expression of transcriptional repressor BLIMP1 and producing Tex ( 33 ). Several approaches to partially reverse the T cell exhaustion phenotype through gene editing or small molecules and enhance the efficacy of immunotherapy have also been found.…”

NR4A3 deficiency in CD8+T cells improves adoptive T cell therapy of cancer

“…In contrast, another group recently reported that the deletion of the three NR4A family members was required to enhance the action of chimeric-antigen receptor (CAR) expressing CD8 + T cells 8 . Furthermore, a recent study showed that NR4A3 deletion in human CAR-T cells was not sufficient to enhance tumor control but that the co-deletion of Nr4a3 and Prdm1 (coding for Blimp-1) is required to decrease exhaustion and improve tumor control 11 . One possible explanation for these differences could relate to the stronger antigenic signal that may lead to more severe exhaustion of CAR-expressing TILs, which might not be overcome by the deletion of only one NR4A member in CD8 + TILs.…”

“…Indeed, NR4A3 deficiency in CD8 + T cells favors the generation of memory precursor effector cells and central memory CD8 + T cells while at the same time enhancing effector functions 7 . Several studies have shown that NR4As also influence CD8 + T cell responses during chronic responses [8][9][10][11] . It was reported that the deletion of the three members of the NR4A family (TKO) enhances the anti-tumor response of CAR-T cells used for adoptive cell therapy (ACT) of tumor-bearing mice 8 .…”

“…In another study, the deletion of NR4A1 was shown to reduce CD8 + T cell exhaustion following chronic infection with LCMV clone 13 and following ACT of tumor-bearing mice 9 . More recently, it was shown that combined inactivation of Nr4a3 and Prdm1 by CRISPR in CAR-T cells increases their functionality and ability to control tumor growth in mouse pre-clinical models 11 . At the molecular level, NR4As directly contribute to the Pdcd1 (coding for PD-1) gene transcription 8 and restrain the accessibility of the chromatin for bZIP transcription factors 8 .…”

The Identification of IL-4 as a Regulator of Chimeric Antigen Receptor T Cell Exhaustion

“…In addition, exhausted T cells experience metabolic changes such as impaired glycolysis 13 . Transcriptional and epigenetic changes include alterations in the activity of several transcription factors including: TCF-7, TOX, T-BET, EOMES, PRDM1, NR4A3, BATF, EGR2, and AP-1 and RUNX family members [14][15][16][17][18][19][20][21][22][23][24][25][26] . In an effort to control the epigenetic response to chronic stimulation, several studies have used genetic engineering tools to overexpress or knockout individual molecules.…”