Nowadays, liver transplantation (LT) is considered a feasible cure for end-stage liver disease (ESLD), and its survival has been estimated to be close to 71% at 5 years and 60% at 10 years.^1,2 Recurrence of Hepatitis C virus (HCV) infection in the post-transplant period is almost universal^3-5; that is to say, up to 10-30% of patients developing cirrhosis 5 years after LT.⁶ Nevertheless, new direct-acting anti-HCV treatments have become available and they reach eradication rates above 87-97%.⁷ With the paritaprevir/ritonavir/ombitasvir/dasabuvir and ribavirin (3D) scheme, a sustained viral response (SVR) of 97% has been reported (CORAL-1 study), with no associated rejection episodes and acceptable tolerability.^5,7

Calcineurin inhibitors (CNI) such as tacrolimus (TAC) and cyclosporine A (CsA) are considered the pillars of immunosuppressive therapy in LT recipients.^4,8,9 TAC is a potent inhibitor of CYP3A and glycoprotein P (P-gp), while CsA inhibits CYP3A, P-gp, and the organic anion transport protein (OATP)-1B1.⁹ Both mechanisms are associated with different interactions, and as a result, drug blood levels are required for close monitoring.¹⁰ The 3D regime can also induce CYP3A4 and can inhibit P-gp and OATP-1B1; thus, potentially noxious drug interactions should be anticipated. Therefore, a dose reduction of CNI can be established to reduce toxicity; however, no recommendations or algorithms are available for LT patients under advanced anti-HCV therapy.

Even though different treatment modalities are described in the guidelines for eradicating HCV infection^7,11, access to advanced anti-HCV therapies is not universal. In Mexico, only some regimes are available. We aimed to evaluate the required dose adjustment of CNI in patients on HCV treatment under the 3D regime.

This is a prospective, observational study. We included adult patients from Unidad de Trasplante Hepático at Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”. Patients were selected and invited to participate between January 2014 and April 2017. All patients were HCV genotype 1 and were receiving a stable CNI dose. Participants were followed in the clinic for at least one year after transplantation. A FibroScan^® or biopsy result ≤ F2 was required. All patients with other genotypes, co-infection with human immunodeficiency virus (HIV), hepatitis B, re-transplantation or multivisceral transplantation were excluded. Patients under other therapeutic regimens were not included. All patients who agreed to participate in the study signed an informed consent form and agreed to be closely monitored throughout the treatment. The Institutional Review Board and Ethics Committee of our center approved the study.

Clinical records were reviewed to collect demographic data, risk factors, comorbidities, clinical presentation, and laboratory data. Research data was extracted into a standardized and structured research format. In all patients, pharmacological interactions were reviewed and adjusted before the initiation of antiviral therapy. TAC or CsA levels in the previous three visits were reviewed to determine the use of a stable drug dose; dosages were adjusted as suggested by Bradi et al.⁵ The trough concentration (C_trough) was determined before treatment initiation to confirm that levels were within adequate ranges. Necessary drug adjustments were applied if necessary, and the patient was re-evaluated at a later date.

All patients received ribavirin and 3D for 24 weeks. TAC was initiated at a dose of 0.5 mg every 7 days or 0.25 mg every 5 days. In the patients on CsA, the total dose was decreased by 1/5 and administered once daily during the morning. The CNI was ingested 1 hour before 3D, in the morning. According to previous studies, TAC dose half-life would increase up to 10 days and levels would stabilize at 5-6 week⁵; CsA, half-life would increase up to 25 hours and would stabilize by day 15.⁵

Patients were evaluated as follows: during the first week of follow-up (visit 1), until three CNI levels were determined (if needed), and they were subsequently measured weekly (visits 2-8) until the eighth week. Thereafter, levels were determined every 4 weeks (visits 9-12) until the end of treatment. After completing HCV therapy, patients were re-evaluated to readjust the CNI dosage (visit 13). CNI levels were measured by chemiluminescent microparticle immunoassay (CMIA). During each patient evaluation, CNI levels were performed. If any change was needed or if a patient needed an unscheduled visit, phone contact was performed.

Statistical analysis

Results are reported with central tendency statistics and the mean ± standard deviation and interquartile range when appropriate. Pharmacokinetic analysis was performed for both TAC and CsA. Dose and blood concentration data were analyzed globally. A mono-compartmental model with oral absorption was used.

Ten patients, out of a total of 22 who received LT during the period, had HCV infection and received the 3D regimen. The general characteristics of the patients are shown in Table 1. Nine patients (90%) received TAC and 1 (10%) CsA. Two patients had a history of grade 2 rejection episodes. No patient developed a rejection episode during the 3D regimen. The mean body weight was 55.76 ± 28.92 kg. The time between LT to treatment initiation was 27.50 months (21.50-36.25 months).

In the TAC group, 4 patients received an initial dose of 0.5 mg every 7 days, and 5 patients received a dose of 0.25 mg every 5 days. The patient on CsA was administered 1/5 of the usual dose. After 24 hours of initiating HCV treatment in the 0.5 mg TAC dose group, an increase between 74.7 and 111% in TAC levels were documented. The dose was adjusted and administered every 10 days. Mean levels during the whole treatment period were 9.07 ± 5.56 ng/mL (Figure 1). The C_trough during the study period was 2 ng/mL and the maximum observed concentration (C_max) was 30 ng/mL (Table 2).

Although the CsA dose was decreased to 10 mg once daily in the only patient receiving CsA, an increase of 400% in blood levels was detected. The drug was withdrawn for 96 hours and once adequate levels were obtained, the CNI was reinitiated at 1/5 of the pre-treatment dose. At follow-up, mean levels were 152.85 ± 54.55 ng/mL, the C_trough during the study period was 66.90 ng/mL and the C_max was 476.70 ng/mL (Table 2).

In our cohort of patients, no adverse effects associated with 3D treatment were seen. The ribavirin dose was adjusted during treatment according to the development of adverse effects. In 30% of patients, it was withdrawn for an average of 8 weeks. At the end of treatment, all patients had a negative viral load and an SVR₂₄ was achieved in all patients. Viral load monitoring and biochemical liver function tests of the patients are reported. (Table 3).

HCV recurrence after LT is universal.^12-15 In some patients, it follows an accelerated course that leads to early allograft failure whereas, in others, it can promote the development of significant fibrosis for years. Previous studies have documented a more aggressive course in some LT recipients, leading to cirrhosis within 5 years.¹²

Antiviral therapy can improve significantly the patients’ outcome, so timely treatment is key in this population. Ideally, antiviral therapy should be initiated before LT so that graft re-infection can be limited, but since this is not always feasible, special measures must be taken in post-LT patients, particularly those on drug interactions with CNI that could potentially preclude or limit their use.

At the moment, multiple treatment options are available with high SVR in LT patients, but in Mexico, only a few exist and they are not universally accessible. Our experience with the 3D regimen was taken from 10 patients, most of them on TAC immunosuppression. Particularly due to potential drug interactions with the protease inhibitor paritaprevir, CNI dose adjustment could be needed with close monitoring.

All our patients met treatment criteria according to the CORAL-1 study¹², and the period between LT to treatment initiation was 27.5 months, which is even higher than the 12 months described in the CORAL-1 study. That allowed us to be certain that the patients were receiving stable immunosuppression doses before initiating 3D treatment.

First, the TAC dose was administered at 0.5 mg every 7 days, as reported initially by Badri et al.⁶; however, we found that our patients required less frequent dosing and it was prolonged to every 10 days and even 17 days, leading to more stable control. When using 0.25 mg, the drug was initially administered twice a week, as suggested in the study by Bradi et al.⁶, but in our cohort it was later adjusted to 5-day intervals, yielding better results. A subsequent publication including 34 patients with LT and 3D treatment, as well as a pharmacokinetic model⁵, agreed with our findings, and the adjustment was maintained.

In the case treated with CsA, 1/5 of the total daily dose was administered once daily; however, blood levels were unexpectedly high, so the dose was administered after 72 h initially and thereafter, and the patient was appropriately controlled.

Although fewer doses were required, we achieved optimal TAC levels and no rejection episodes were documented. We are aware of the high C_max reported but it was comparable with those reported by Bradi et al.⁵ In our study, no serious adverse reactions were observed during the follow-up and levels remained stable at high ranges for 6 weeks. Subsequently, an established dose of 0.25 mg was administered, follow-up was uneventful and there was no detrimental effect on the SVR₁₂.

As expected, the most commonly observed side effect associated with ribavirin use was the development of anemia. In our population, the drug required withdrawal in 30% (n=3) of cases, for up to 4 weeks. This strategy was not associated with poor treatment response and did not affect the SVR₁₂.

We propose that this immunosuppressing regime is safe, but it requires closer surveillance and lower doses of CNIs for Mexican patients. In this cohort, a followed-up over 28 months after LT and an SVR₁₂ of 100% was documented. At the moment, SVR₂₄ is 100% and SVR 1-year after follow-up was 100%.

Our study has some limitations that should be discussed. We are aware of the small number of patients included in this study and that the scheme is currently not considered ideal due to the interactions reported with CNI, but in countries like Mexico, where there is limited access to other DAA schemes, this treatment could be considered a feasible option that requires adaptation and surveillance.