No Effect of Sirolimus for Kaposi Sarcoma in a Renal Transplant Recipient

In recently published studies (1, 2), it was shown that sirolimus inhibits the progression of dermal Kaposi sarcoma in kidney transplantation. The report by Stallone et al. (1) studied 15 recipients of a cadaveric kidney transplant who had biopsy-proven Kaposi sarcoma. When Kaposi sarcoma was diagnosed, administration of cyclosporine and mycophenolate mofetil was stopped and administration of sirolimus was started to maintain trough blood levels of 6–10 ng/mL. The authors found that, 3 months after initiation of sirolimus therapy, cutaneous Kaposi sarcoma lesions could not be identified in any patient. We report a 36-year-old man with Alport syndrome who received a cadaveric kidney graft 9 years after the start of hemodialysis. The immunosuppression regimen consisted of cyclosporine (trough levels 250–350 ng/mL), mycophenolate mofetil (1,000 mg twice daily), and prednisone (tapered to 7.5 mg by month 3 and stopped by month 9); 20 mg of basiliximab was given on day 0 and day 4 (Fig. 1). A borderline acute cellular rejection at 4 months was treated with methylprednisolone and replacement of cyclosporine by tacrolimus (trough levels 10–15 ng/mL tapered to 5–8 ng/mL).FIGURE 1.: Clinical course of Kaposi sarcoma after renal transplantation.Nine months after transplantation, this patient developed 24 cutaneous lesions of Kaposi sarcoma proven by skin biopsy and HHV8 positivity on immunohistochemical study. No lymph node or visceral involvement was found. To reduce immunosuppression, mycophenolate was switched to azathioprine and tacrolimus was replaced by prednisone (10 mg) 1 month later. Three months later, no regression of the cutaneous lesions was observed. Therefore, after publication of the impressive results by Stallone et al. (1), we stopped administration of azathioprine and started treatment with sirolimus (loading dose of 0.18 mg per kg body weight followed by 0.05 mg/kg/d; trough blood levels 6–10 mg/mL). Three months later, a graft biopsy performed as a result of a transient increase of serum creatinine revealed no rejection. However, 6 months after the initiation of sirolimus, the Kaposi sarcoma is unchanged without any remission of the dermal lesions. To our knowledge, this is the first published experience of dermal Kaposi sarcoma after kidney transplantation treated according to the protocol of Stallone et al. (1). Aside from that report (1), we are aware of 10 published cases of successful treatment of Kaposi sarcoma with sirolimus (3–5). To our knowledge, there is no published experience of unsuccessful treatment with sirolimus until now. The patient described herein had the same clinical characteristics as the patients presented by Stallone et al. (1): age, sex, panel reactive antibody level, time from transplantation to diagnosis, number of lesions, and serum creatinine level. Diagnostic criteria, therapeutic intervention, and follow-up were also identical. Therefore, it remains unclear why we could not reproduce the excellent results. In conclusion, further cases of Kaposi sarcoma should be treated according to the protocol of Stallone et al. (1) to learn about the general applicability of the published results. To avoid publication bias and to overview the effect of sirolimus, it is important to also publish the negative results. Bernard Descœudres Olivier Giannini Clinic for Transplantation Immunology and Nephrology University Hospital Basel Basel, Switzerland Tanja Graf Department of Dermatology University Hospital Basel Basel, Switzerland Jürg Steiger Michael Mayr Clinic for Transplantation Immunology and Nephrology University Hospital Basel Basel, Switzerland