Incidence of Malignancies in Patients Treated With Sirolimus Following Heart Transplantation

Background: Malignancy is a major cause of late post-heart transplantation (HT) mortality. Sirolimus (SRL) exerts antiproliferative properties and its long-term use in HT as primary immunosuppression (IS) is associated with decreased mortality risk that is not fully explained by attenuation of cardiac allograft vasculopathy progression. Objectives: This study sought to examine whether conversion from calcineurin inhibitor (CNI)-based to SRL-based IS was associated with decreased risk of malignancy post-HT. Methods: Overall, 523 patients underwent HT between 1994 and 2016 at a single institution. The main outcomes included incidence of overall de novo malignancies (excluding non-melanoma skin cancers [NMSCs]), post-transplantation lymphoproliferative disorders (PTLD), and first and subsequent primary occurrences of NMSC post-HT. Results: The study identified 307 patients on SRL-based and 216 on CNI-based maintenance IS. Over a median follow-up of 10 years after HT, overall de novo malignancies (non-NMSC) occurred in 31% of CNI patients and in 13% of SRL patients (adjusted hazard ratio [HR]: 0.34; 95% confidence interval [CI]: 0.18 to 0.62; p < 0.001). The incidence of the first NMSC was similar in the SRL and CNI groups (HR: 0.92; 95% CI: 0.66 to 1.28; p = 0.62). However, conversion to SRL was significantly associated with a decreased risk of subsequent primary occurrences of NMSC compared with that of CNI (adjusted HR: 0.44; 95% CI: 0.28 to 0.69; p < 0.001). The adjusted PTLD risk was significantly decreased in the SRL group (HR: 0.13; 95% CI: 0.03 to 0.59; p = 0.009). Late survival post-HT was markedly decreased in patients who developed non-NMSC, PTLD, or non-PTLD compared with patients who did not develop these malignancies, whereas NMSC had no significant effect on survival. Conclusions: Conversion to SRL was associated with a decreased risk of all de novo malignancies, PTLD, and subsequent primary occurrences of NMSC after HT. These findings provided further explanation of the late survival benefit with long-term SRL use.