Complete regression of visceral Kaposi's sarcoma after conversion to sirolimus

The prevalence of Kaposi's sarcoma (KS) is much greater in organ transplant recipients than it is in the general population. Its etiology appears to be related to geographic, genetic, and viral factors. Treatment of transplant-related KS has, until now, consisted mainly of reduction of, or withholding of, immunosuppression, often with deleterious effects on both graft and patient survival. In recent years, the immunosuppressive drug, sirolimus, has been demonstrated as possessing anti-neoplastic properties in both in vitro and animal models. In view of these properties and some preliminary clinical experience, we postulated that sirolimus would be beneficial in our patients who developed transplant-related KS. Here, we report the first case of a patient with both cutaneous and visceral KS who was successfully treated in the Middle East by conversion from a cyclosporine-based to a sirolimus-based immunosuppression regimen. The KS regressed completely within a few months after the conversion. The chronologic events and the extensive documentation, which included repeat computed tomography scans, are very suggestive of a selective anti-neoplastic effect of sirolimus.