Date of report 22 Sep 2019

Reported case interaction between
Cobicistat and Tacrolimus

40-year old man, referred to our centre for evaluation of kidney transplantation. End-stage renal disease secondary to glomerulonephritis in 2006. History of poor compliance to antiretroviral (ARV) therapy, although not documented HIV resistance. Several ARV regimens since 2006 including ATV/r-3TC-AZT, DRV/r-3TC-AZT, DRV/r-3TC-ABC and DRV/r-RAL (ongoing at the time of referral). Persistently detectable VL, around 200-300 copies/mL, while receiving DRV/r-RAL. A genotypic resistance test did not amplify the virus. A pro-viral resistance test was requested. PROT and RT were amplified, with no detectable mutations, INT was not amplified. It was then decided to modify ART to DRV/r 600/100 bid + DTG 50mg bid, becoming rapidly undetectable. Regimen was later simplified to DRV/c 800/150 qd + DTG 50mg bid. The patient received kidney transplantation in June 2017. Given the extremely limited data available for cobicistat-tacrolimus co-administration, 1.5 mg of tacrolimus was initially given with therapeutic drug monitoring performed 48 and 72hs post-dose. Levels increased up to 23.3 ng/mL. The patient was discharged on tacrolimus 1.5 mg/48hs, which was later modified to 0.5mg/48hs, maintaining tacrolimus plasmatic levels between 7 and 14 ng/mL. One year after kidney transplantation, still on DRV/c 800/150mg QD and dolutegravir 50 mg BID, the patient developed cutaneous SK, adding then sirolimus to the immunosuppressive regimen, at a dose of 0.5mg/ 4 days (sirolimus levels ranging between 3.2 and 6 ng/mL). The patient is currently well, no evidence of SK progression, stable renal function, undetectable HIV VL and CD4 T cells >1000/ul.