Introduction: The aim was to update our experience with Sirolimus (SRL) in intestinal transplanted (IT) pediatric patients.

Patients and methods: Between 1999 and 2018, 107 TI in 83 patients were performed at a median age of 38 months at transplant (range 6 m- 30 yo); 18 were retransplanted, 6 of them twice. Initial manteinance treatment protocol was Tacrolimus (TAC). Those patients who were partially or completely converted to SRL were retrospectively reviewed.

Results: Since 2008, SRL was used in 31 patients, after a median of 17 months since transplant (range 1 m- 6 years). The main indication was TAC toxicity in 16 (worsening of the renal function +/- hypertension in 13, hypertrophic myocardiopathy in 2, neuropathy in 1) and/or immunological complications in 17 (chronic rejection in 1, hemolytic anemia in 7, GVHD in 5, PTLD in 3, and neutropenia in 1). On the other hand, 10 patients had past medical history of rejection (6 of them moderate/severe), 9 had suffered GVHD, and 8 patients had been retransplanted prior to the conversion. Sirolimus was indicated alone in 20 patients when TAC was contraindicated and combined with TAC in 12 with higher risk of rejection, such as in retransplanted patients.

After a median follow-up of 77 months (1m-11years), the renal function improved in all patients along the follow-up (mean cistatine levels decreased from 3,50±0,52 mg/dl to 1,14±0,31). We did not find more immunological complications after the conversion to SRL compared with those patients on TAC. Six patients died, due to the progression of chronic rejection (1) or GVHD (4), having appeared these complications before the conversion. However, 2 patients developed chronic rejection after the conversion, one of them has recently been retransplanted after 12 years since the first ISBT (10 years with SRL). The second one died 7 years after his third transplant, having taken SRL for the 3 last years. The other 25 are doing well with normal graft function. At the moment of the study, 47 of the global series are alive and 25 of them are on SRL.

Conclusions: Although TAC remains to be the maintenance treatment of choice in IT, half of our alive patients needed conversion to SRL along the follow-up. It seems safe and effective, although it does not totally prevent from immunological complications either. Accumulated experience is encouraging to widen its use in younger children, complex scenarios and after less time elapsed since transplant.