74 year old female patient with history of melanoma treated with pembrolizumab stopped 6 months ago, now has swelling and pain in knees, hands with onset of 3 weeks, responsive to high prednisone dose 40mg per day, no myalgia, no rashes, no breathing problems, no dysphagia. she has high esr and high pcr, negative ana, negative anti ccp antibodies, negative rheumatoid factor, normal C3, C4, normal CK, LDH, ASAT, ALAT, normal serum protein electrophoresis. she has positive EJ antibody in high titre, normal thoracic CT scan. what is the recommended corticoid sparing treatment? what is the best imunosupressive treatment in a patient with a history of cancer?