Nicotinamide Chemoprevention for Keratinocyte Carcinoma in Solid Organ Transplant Recipients - Pivotal Trial

As patients live longer after receiving an organ transplant, there is a need to reduce the long-term side effects of the drugs used to prevent organ rejection. In particular, long-term use of these drugs increases the risk of skin cancer. Skin cancer is now a leading cause of illness and disfigurement after kidney, liver, heart, and lung transplantation. Given the increased risk and burden of skin cancer in transplant recipients, prevention is critical. Nicotinamide is a form of Vitamin B3 that has been shown to protect against skin cancer in the general population. However, it is unclear whether nicotinamide is effective among immune-suppressed transplant recipients. Investigators will conduct a clinical trial involving multiple transplant centres in Canada to evaluate whether oral nicotinamide (500 mg twice daily) is effective and safe for preventing skin cancer. Investigators will recruit 396 high-risk adult kidney, liver, heart, and lung transplant patients who have previously had at least one skin cancer. Patients will receive nicotinamide or sham tablets for up to 4 years. The results will inform efforts to improve the long-term health of transplant recipients.

Inclusion Criteria: * Age ≥ 18 years old * Kidney, liver, heart, or lung transplant at least two years ago * History of at least one prior histologically-confirmed keratinocyte carcinoma or squamous cell carcinoma in situ * Currently immunosuppressed with a calcineurin inhibitor-based regimen (cyclosporine or tacrolimus) * Able to attend follow-up visits Exclusion Criteria: * Use of nicotinamide or niacin (≥250 mg daily) within past 12 weeks * Untreated localized skin cancer at baseline (patient can enrol after skin cancer treatment) * Biopsy-confirmed acute rejection episode within the past 12 weeks * Active liver disease (high AST \>3 times or bilirubin \>1.5 times) * Severe kidney disease (estimated glomerular filtration rate \