Effect of Converting From Calcineurin Inhibitor– to Sirolimus-Based Immunosuppressant Regimen on Breast Fibroadenoma Among Kidney Transplant Patients

Abstract

The incidence rate of breast fibroadenomas is higher among female kidney transplant (KT) patients treated using cyclosporine (CsA) for immunosuppression than in the general population. As such, there is an effort to convert immunosuppression from CsA or tacrolimus to sirolimus. Our aim was to assess the reversibility of a breast fibroadenoma after conversion in a small cohort of female KT recipients. This was an open-label, single-arm study including 128 female KT recipients, with a positive finding of a breast fibroadenoma in 15. Lesions were classified according to the Breast Imaging Reporting and Data System (BIRADS). Among these 15, a total of 7 converted from tacrolimus to sirolimus and 8 converted from CsA. We measured the change in BIRADS category and hormone and cytokine levels from baseline to 12 months after conversion. The primary outcome was progression or reversal of existing fibroadenomas at 12 months after conversion. Secondary outcomes were differences in hormone and cytokine levels. Conversion from CsA or tacrolimus to sirolimus had no significant effect on the BIRADS classification. However, conversion to sirolimus did produce a significant decrease in the level of transforming growth factor β cytokine, this level being closely associated with fibroadenomas. Conversion from a calcineurin inhibitor to sirolimus can block the progression of fibroadenomas. Further research is needed to confirm our results.