MutT Homolog 1 Inhibitor Karonudib Attenuates Autoimmune Hepatitis by Inhibiting DNA Repair in Activated T Cells

Targeting the nucleic acid oxidative damage repair enzyme MTH1: a promising therapeutic option

The accumulation of reactive oxygen species (ROS) plays a pivotal role in the development of various diseases, including cancer. Elevated ROS levels cause oxidative stress, resulting in detrimental effects on organisms and enabling tumors to develop adaptive responses. Targeting these enhanced oxidative stress protection mechanisms could offer therapeutic benefits with high specificity, as normal cells exhibit lower dependency on these pathways. MTH1 (mutT homolog 1), a homolog of Escherichia coli's MutT, is crucial in this context. It sanitizes the nucleotide pool, preventing incorporation of oxidized nucleotides, thus safeguarding DNA integrity. This study explores MTH1's potential as a therapeutic target, particularly in cancer treatment, providing insights into its structure, function, and role in disease progression.

Mitotic MTH1 Inhibitors in Treatment of Cancer

The DNA damage response (DDR) protein MTH1 is sanitising the oxidized dNTP pool and preventing incorporation of oxidative damage into DNA and has an emerging role in mitosis. It is a stress-induced protein and often found to be overexpressed in cancer. Mitotic MTH1 inhibitors arrest cells in mitosis and result in incorporation of oxidative damage into DNA and selective killing of cancer cells. Here, I discuss the leading mitotic MTH1 inhibitor TH1579 (OXC-101, karonudib), now being evaluated in clinical trials, and describe its dual effect on mitosis and incorporation of oxidative DNA damage in cancer cells. I describe why MTH1 inhibitors that solely inhibits the enzyme activity fail to kill cancer cells and discuss if MTH1 is a valid target for cancer treatment. I discuss emerging roles of MTH1 in regulating tubulin polymerisation and mitosis and the necessity of developing the basic science insights along with translational efforts. I also give a perspective on how edgetic perturbation is making target validation difficult in the DDR field.

Targeting the DNA repair enzymes MTH1 and OGG1 as a novel approach to treat inflammatory diseases

Autoimmune diseases and acute inflammation like sepsis cause significant morbidity and disability globally, and new targeted therapies are urgently needed. DNA repair and reactive oxygen species (ROS) pathways have long been investigated as targets for cancer treatment, but their role in immunological research has been limited. In this MiniReview, we discuss the DNA repair enzymes MTH1 and OGG1 as targets to treat both T cell-driven diseases and acute inflammation. The MiniReview is based on a PhD thesis where both enzymes were investigated with cell and animal models. For MTH1, we found that its inhibition selectively kills activated T cells without being toxic to resting cells or other tissues. MTH1 inhibition also had an alleviating role in disease models of psoriasis and multiple sclerosis. We further identified a novel MTH1low ROSlow phenotype among activated T cells. Regarding OGG1, we demonstrated a mechanism of action of the OGG1 inhibitor TH5487, which prevents the assembly of pro-inflammatory transcription factors and mitigates acute airway infection in mouse models of pneumonia. Hence, we propose both enzymes to be promising novel targets to treat inflammation and suggest that redox and DNA repair pathways could be useful targets for future immunomodulating therapies.