Inclusion Criteria:  Kidney transplant ≥ 12-months ago ongoing, standard immunosuppression regimen current CKD EPI estimated (43) glomerular filtration rate (eGFR) ≥ 15 ml/min per 1.73 m2) Prior history of at least one NMSC  Exclusion Criteria:  Kidney transplant <12-months ago, treatment for acute rejection <= 3-months ago, or current eGFR< 20 Known history of active liver disease/ transaminitis [alanine aminotransferase, ALT > 1.5 X upper limit of normal] Serum phosphorus < 2.0 mg/dL or average ≤ 100 × 10(9)/mL platelets Internal malignancy, metastatic SCC, or invasive melanoma within the past 5-years Overwhelming numbers of current skin cancers or large areas of confluent skin cancer at baseline preventing accurate assessment and counting of new skin cancers Field treatment for AKs within the past 4-weeks, preventing accurate assessment of AKs Patients begun on acitretin or other oral retinoids, or mTOR inhibitors within the past 6-months (If stably taking for more than six months, they may participate) Gorlin's syndrome or other genetic skin cancer syndrome Patients unavailable for follow-up for the duration of the study because of social/ geographical reasons, or general frailty Pregnancy or lactation (all women of childbearing will be required to use contraception throughout the study) Patients taking supplemental NAM within the past 4-weeks