Inclusion Criteria:
- Male or female subject aged ≥ 18 years.
- Confirmed diagnosis of CLL or small lymphocytic leukemia (SLL) per iwCLL 2018 criteria.
- History of ≥1 non-melanoma skin cancer (NMSC) diagnosed within the last 5 years
- Adequate liver function as defined as:
- Total Bilirubin ≤ 1.5x institutional upper limit of normal (ULN)
---Subjects with a known diagnosis of Gilbert's Syndrome: direct bilirubin ≤ 1.5x ULN
- AST(SGOT)/ALT(SGPT) ≤ 3 × institutional ULN
- For female subjects: Negative pregnancy test or evidence of post-menopausal status. The post-menopausal status will be defined as having been amenorrheic for 12 months without an alternative medical cause. The following age-specific requirements apply:
--Women < 50 years of age:
- Amenorrheic for ≥ 12 months following cessation of exogenous hormonal treatments; and
- Luteinizing hormone and follicle-stimulating hormone levels in the post-menopausal range for the institution; or
- Underwent surgical sterilization (bilateral oophorectomy or hysterectomy).
- Women ≥ 50 years of age:
- Amenorrheic for 12 months or more following cessation of all exogenous hormonal treatments; or
- Had radiation-induced menopause with last menses >1 year ago; or
- Had chemotherapy-induced menopause with last menses >1 year ago; or
- Underwent surgical sterilization (bilateral oophorectomy, bilateral salpingectomy, or hysterectomy).
- Female subjects of childbearing potential and male subjects with a sexual partner of childbearing potential must agree to use a highly effective method of contraception.
Exclusion Criteria:
- Received cytotoxic chemotherapy (including fludarabine, cyclophosphamide, bendamustine, or chlorambucil) within the last 6 months
- Received allogeneic stem cell transplant within the last 6 months.
- Taking nicotinamide or niacin supplements within the last 4 weeks.
- Taken acitretin or other oral retinoids within the past 6 months
- Received field treatment for AKs (topical use of 5-fluorouracil, imiquimod, diclofenac, retinoids; topical photodynamic therapy for AKs; laser resurfacing or chemical peel treatments for AKs) within the previous 4 weeks
- Large areas of confluent skin cancer at baseline preventing accurate assessment and counting of individual new skin cancers
- Need for ongoing carbamazepine use (possible interaction with nicotinamide)
- Severe GI malabsorption that may interfere with absorption of nicotinamide (per investigator's discretion)
- Patients with an expected life expectancy < 2 years
- Current evidence of uncontrolled, diabetes.
- Current evidence or history of peptic ulcer disease.
- Known HIV infection with a detectable viral load within 6 months of the anticipated start of treatment.
Note: Subjects on effective antiretroviral therapy with an undetectable viral load within 6 months of the anticipated start of treatment are eligible for this trial.
- Known active uncontrolled infection.
- Medical, psychiatric, cognitive, or other conditions that may compromise the subject's ability to understand the subject information, give informed consent, comply with the study protocol or complete the study.
- Known prior severe hypersensitivity to investigational product (IP) or any component in its formulations (NCI CTCAE v5.0 Grade ≥ 3).
- Subjects taking prohibited medications as described in study protocol. A washout period of prohibited medications for a period of at least five half-lives or as clinically indicated should occur before the start of treatment.
- Have ever received a solid organ transplant and are currently taking immunosuppressive medications.