Arginine (ARG) is a basic non-essential amino acid well known to participate in physiological functions such as i) vascular tone homeostasis as contributing to the production of nitric oxide (NO) and ii) immune response control, through NO synthase (NOS) and Arginase enzymes, respectively.
A dysregulation in ARG catabolism has been already linked to tumor progression and immune escape. Indeed, overexpression of Arginase in tumor and immunosuppressive cells (eg. Myeloid Derived Suppressor Cells) contributes to an excessive use of ARG thereby limiting its availability for effector immune cells. Arginase represents therefore an attractive therapeutic target to restore anti-tumor immunity and inhibitors (eg. INCB001158) are currently under clinical development in several cancer indications. ARG measurement in biological samples such as plasma or serum thus represents a suitable surrogate marker for novel Arginase inhibitors. Our new validated IS-I-0400 ELISA kit allows for the determination of ARG in serum and plasma samples of a volume as low as 20μL and with a sensitivity of 2.1µM.
(A) ARG was quantified in human plasma samples from 19 healthy donors and 46 cancer patients from several histotypes using IS-I-0400 Arginine ELISA kit. As depicted, ARG level was lower in cancer patients than in healthy subjects thus arguing for an exagerated Arginase activity in cancer patients. (B) Microdialysis was performed in MCA205-sarcoma tumor-bearing mice in both tumor and non-tumor regions and collected microdialysates were subjected to ARG quantification using IS-I-0400 ELISA kit. As expected, Arginine level was lower in the tumor compartment when compared to the subcutaneous counterpart, thereby evidencing high tumoral Arginase activity. ****p<0.0001