A 45 year old male, Sonu presented to OPD with severe pain in the knee and shoulder joint. On examination and fuher investigations, a diagnosis of rheumatoid ahritis was made and the patient was staed on methotrexate 15mg weekly. However, even after 6 months of using methotrexate, recurrent episodes of ahritis continued. The physician wanted to add another DMARD that inhibit the pyrimidine synthesis by inhibiting dihydroorotate dehydrogenase enzyme. Which of the following drug, physician is thinking about?