Case 6:
A 21-year-old male with CF (F508del/F508del/Y301C) status post liver transplant in 2009 for CFLD. He was initially managed with corticosteroids and tacrolimus and then transitioned to tacrolimus monotherapy with a goal trough of 3-5 ng/mL. Since transplant, all transplant related labs have been remained within acceptable ranges. He has not had any episodes of rejection. His baseline best ppFEV1 during 2019 was 77%. In December 2019, he started full dose elx/tez/iva. Baseline LFTs, bilirubin, and a tacrolimus trough were obtained prior to the start of therapy and were WNL. LFTs were repeated one week and two weeks after starting therapy and remained WNL. His tacrolimus concentration after one week was 3.3 ng/mL (goal: 3-4 ng/mL) and was not repeated after two weeks due to stability. Labs were then spaced to three months after the start of therapy and again remained stable WNL including a tacrolimus of 3.6 ng/mL. During therapy, he experienced a change in stool patterns including constipation and loose stools; however, this was difficult to differentiate from baseline stool issues. He also noted sometimes feeling more fatigued than previous in the evenings. Overall, since starting therapy his baseline cough diminished and respiratory symptoms improved though without marked change to ppFEV1 which remained at 78%.