Inclusion Criteria:

- Recipients of renal allograft with current actinic keratosis I or II or successfully
treated actinic keratosis III (inclusion possible immediately after completed wound
healing from surgical excision), invasive squamous cell carcinoma (SCC), basal cell
carcinoma

- age 18 years and older

- minimum period of 6 month after renal transplantation

- stable renal function and a calculated creatinine clearance of at least 40 ml/min

- written informed consent

- proteinuria ≤ 800 mg/d at time of enrolment

- successfully treated solid tumor (no recurrence or metastasis in the last 2 years)

Exclusion Criteria:

- Current Sirolimus- or Everolimus- intake

- Instable graft function (creatinine clearance < 40 ml/min)

- Graft rejection within the 3 previous months

- Proteinuria > 800 mg/d

- Non-controlled hyperlipidemia (Cholesterol >7,8 mmol/l (300 mg/dl), Triglycerides > 4
mmol/l (350 mg/dl)

- Leucopenia < 2500/nl

- Thrombocytopenia < 90/nl

- Pregnancy or breastfeeding

- Women of childbearing age without highly effective contraception

- Known allergy to macrolides

- Current participation in other studies

- Refusal to sign informed consent form

- Neoplasm other than defined as inclusion criteria

- All contraindications to SRL (see package insert, appendix)

- Persons who are detained officially or legally to an official institute

- Acute infections (mycotic, viral or bacterial)

- Current intake of other substances with known nephrotoxicity

- Severe liver dysfunction

- Current intake of CY3A4-inhibitors (e.g. ketoconazole, voriconazole, itraconazole,
telithromycin or clarithromycin) or CY3A4-inductors (rifampicin, rifabutin)

- sucrose-isomaltase deficiency, fructose intolerance, glucose-galactose intolerance

- azathioprine: known allergy to azathioprine or 6-mercaptopurine, severe bone marrow
dysfunction, pancreatitis, vaccination with live vaccine

- tacrolimus: known allergy to tacrolimus

- mycophenolatmofetil: known allergy to mycophenolatmofetil, neutropenia, severe active
gastrointestinal tract disease, Lesch-Nyhan syndrome or Kelley-Seegmiller syndrome,
current intake of azathioprine

- cyclosporine: known allergy to cyclosporine, increased intracranial pressure