{"6-mercaptopurine can be affected by a patient's TPMT and NUDT15 phenotype. This patient is predicted to be a NUDT15 possible intermediate metabolizer and is at risk for myelosuppression with normal doses of 6-mercaptopurine. Initiate therapy at 30-80% of standard starting dose If starting dose is ≥75 mg/m2/day (for malignancy) or ≥1.5 mg/kg/day (for non-malignancy). If starting dose is already below normal recommended starting dose (i.e., <75 mg/m2/day or <1.5 mg/kg/day), dose reduction might not be recommended. During therapy, adjust the doses of 6-mercaptopurine based on the degree of myelosuppression and disease-specific guidelines. It usually takes at least 2-4 weeks of stable dosing to reach steady state after each dose adjustment. If myelosuppression occurs, and the patient is on combination therapy, emphasis should be on reducing 6-mercaptopurine over other agents. Because a TPMT genotype does not appear to have been ordered for this patient, it is not known if TPMT results would further influence the recommended dose or drug. If 6-mercaptopurine is required and TPMT genotype status is unknown, consider evaluating TPMT erythrocyte activity to assess TPMT phenotype. Erythrocyte TPMT activity test results can be falsely low at diagnosis of leukemia and is unreliable in the case of recent red blood cell transfusions. Monitor closely for toxicity. Please consult a clinical pharmacist for more information."}