Yang et al. found that methotrexate (MTX) competitively inhibited the membrane cGAMP hydrolase ENPP1, which both enhanced immune cell activation by preventing loss of exogenous cGAMP, and inhibited downstream accumulation of suppressive adenosine. In addition, MTX activated STING in cancer cells by inducing DNA damage. MTX synergized with radiation (IR) and ICB in vivo, increasing infiltration of CD8+ and CD11c+ cells into cold tumors. Addition of MTX to IR/ICB in an open-label trial enhanced responses vs. historical controls, where response was correlated with baseline ENPP1/cGAS abundance and post-treatment increases in IFN pathway cytokines.
Contributed by Morgan Janes
ABSTRACT: Low-dose methotrexate (MTX) is the first-line drug for treating rheumatoid arthritis as an immunosuppressor. We have identified that low-dose MTX exhibits antitumor immune activity. MTX treatment reduced tumor metastasis and enhanced the efficacy of radiation therapy and immune checkpoint blockade therapy in mice. Mechanistically, MTX selectively induced DNA damage, cGAS-STING [cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING)] pathway activation, and cGAMP generation in cancer cells. Furthermore, MTX bound to the substrate-binding pocket of ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), inhibiting ENPP1-mediated cGAMP hydrolysis and adenosine generation. Consequently, MTX reduced extracellular adenosine and enhanced host STING-mediated antitumor immunity. In addition, a preliminary clinical trial demonstrated promising efficacy and safety of low-dose MTX in combination with immunotherapy and radiotherapy for patients with unresectable or metastatic solid tumors, showing improved outcomes compared with historical controls. These results highlight the previously unrecognized immunostimulatory functions of MTX and provide a rationale for combining MTX with tumor immunotherapy and radiotherapy in clinical settings.
Author Info: (1) School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub Lane Xiangshan, Hangzhou 310024, China.
Author Info: (1) School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub Lane Xiangshan, Hangzhou 310024, China. Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (2) School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, Jiangsu, China. (3) School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, Jiangsu, China. (4) School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, Jiangsu, China. (5) Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. Division of Life Sciences and Medicine, University of Science and Technology of China, 443 Huangshan Road, Hefei 230026, Anhui, China. (6) Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, Jiangsu, China. (7) Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (8) Shanghai Key Laboratory of Gastric Neoplasms, Department of Surgery, Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. (9) Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China. (10) Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (11) Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (12) Department of Analytical Chemistry, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. (13) Department of Analytical Chemistry, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. (14) Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (15) School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, Jiangsu, China. (16) Yancheng No. 1 People's Hospital, Affiliated Hospital of Medical School, Nanjing University, 66 South People's Road, Yancheng 224000, China. (17) Yancheng No. 1 People's Hospital, Affiliated Hospital of Medical School, Nanjing University, 66 South People's Road, Yancheng 224000, China. (18) School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub Lane Xiangshan, Hangzhou 310024, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (19) Yancheng No. 1 People's Hospital, Affiliated Hospital of Medical School, Nanjing University, 66 South People's Road, Yancheng 224000, China. (20) School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub Lane Xiangshan, Hangzhou 310024, China. Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. (21) School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub Lane Xiangshan, Hangzhou 310024, China. Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China. School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 138 Xianlin Road, Nanjing 210023, Jiangsu, China. Division of Life Sciences and Medicine, University of Science and Technology of China, 443 Huangshan Road, Hefei 230026, Anhui, China.
