Potent and histone deacetylase 3 (HDAC3)-specific PROTAC XZ9002 is reported here.

An effective cancer therapy requires killing cancer cells and targeting the tumor microenvironment (TME). Searching for molecules critical for multiple cell types in the TME, we identified NR4A1 as one such molecule that can maintain the immune suppressive TME. Here, we establish NR4A1 as a valid target for cancer immunotherapy and describe a first-of-its-kind proteolysis-targeting chimera (PROTAC, named NR-V04) against NR4A1. NR-V04 degrades NR4A1 within hours in vitro and exhibits long-lasting NR4A1 degradation in tumors with an excellent safety profile. NR-V04 inhibits and frequently eradicates established tumors. At the mechanistic level, NR-V04 induces the tumor-infiltrating (TI) B cells and effector memory CD8+ T (Tem) cells and reduces monocytic myeloid-derived suppressor cells (m-MDSC), all of which are known to be clinically relevant immune cell populations in human melanomas. Overall, NR-V04–mediated NR4A1 degradation holds promise for enhancing anticancer immune responses and offers a new avenue for treating various types of cancers such as melanoma.

Histone deacetylase 6 (HDAC6) is a unique isozyme in the HDAC family with various distinguished characters. HDAC6 is predominantly localized in the cytoplasm and has several specific nonhistone sub...

Orphan nuclear receptor 4A1 (NR4A1, Nur77) plays a crucial role in regulating immune cell metabolism and function within the tumor microenvironment (TME), thus influencing cancer progression and serving as a potential therapeutic target for cancer immunotherapy. A comprehensive review discussing the multifaceted roles of NR4A1 in immune cells and the exploitation of that knowledge for therapeutic development is lacking in the field. This review explores diverse functions of NR4A1 in tumor-associated immune cells, including T cells, monocytes, natural killer cells, B cells, dendritic cells, macrophages, and neutrophils. NR4A1 contributes to immune regulation by impacting cytokine production, cell differentiation, and immune cell exhaustion. We highlight how NR4A1 in immune cells within the TME may be either a positive (e.g., macrophages in colon cancer) or negative prognostic factor (e.g., T cells in melanoma), depending on the cancer and immune cell context. Additionally, this review also highlights potential therapeutic strategies targeting NR4A1, leading to its inhibition, activation, or degradation to restore immune cell function and enhance anti-tumor immunity. Such therapies could potentially improve patient outcomes by altering immune cell behaviors, blocking intrinsic tumor growth pathways, or via both mechanisms. However, the development of NR4A1-targeted therapies will be dependent on further research to better understand lineage-specific roles of NR4A1 and the underlying mechanisms across different cancer types and immune cells.