Evaluation of the Benefits of Administering Immunosuppressive Drugs as Single Daily Doses Over the First Year After Liver Transplantation (EASY)

World Health Organization considers non-adherence has a strong negative impact on the health of patients with chronic diseases. In transplantation, adherence to immunosuppressive drug regimens associates with late rejection and graft loss making it a critical determinant of patient outcome. The prevalence of non-adherence in transplant patients, including liver transplant patients, can be as high as 40%. Among others, life-long intake and complexity of immunosuppressive regimen make patients prone to non-adherence. For instance, non-adherence is more prevalent among patients with higher numbers of immunosuppressive drugs. One of the most commonly cited causes of non-adherence is forgetfulness and disruptions in routine, with the evening dose of twice daily regimens being the most likely to be affected6. Besides non-adherence, the constraints generated in everyday life by immunosuppression (including timely and regular drug intake) and the complexity of the immunosuppressive regimens represent a burden for the patients and are probably associated with a health-related quality of life deterioration. Therefore, long-term adherence and quality of life after liver transplantation might be improved by using a well-tolerated and easy-to-handle immunosuppressive regimen.

The immunosuppressive regimen after liver transplantation is in most cases based on different combinations of tacrolimus, mycophenolate mofetil and corticosteroids. While corticosteroids are administered once daily, tacrolimus can be administered either twice-daily (BID) as an immediate-release, or once-daily (QD) as an extended-release formulation. Among once-daily tacrolimus formulations, LCP-tacrolimus (ENVARSUS XR®) is approved for the prevention of transplant rejection in adult liver allograft recipients. It has demonstrated similar outcomes compared to immediate-release tacrolimus BID, in both kidney and liver transplantation. Mycophenolate has only been approved for BID administration, preventing from taking all immunosuppressive drugs once daily. Yet, single daily dosing would probably contribute to better adherence and quality of life in patients receiving a life-long treatment.

Although the half-life of mycophenolic acid (MPA), the active moiety of mycophenolate mofetil (MMF) is compatible with once-daily administration, no published randomized clinical study has ever evaluated the efficacy and safety of MMF administered QD.

The narrow therapeutic index and wide pharmacokinetic variability of tacrolimus and mycophenolate justify individual dose adjustment by means of therapeutic drug monitoring (TDM), in order to minimize the risk of acute rejection and the occurrence of adverse events. For tacrolimus, TDM is generally based on the trough concentration (C0) and sometimes on the area under the concentration-time curve (AUC), while for mycophenolate it should be based on the AUC of MPA. However, the dose adjustment of MMF in liver transplant patients is most of the time performed a posteriori, based on clinical signs of inefficacy of toxicity.

Limited sampling strategies with maximum a posteriori Bayesian estimation have been developed by our team for both molecules in adult liver transplant patients to estimate their AUC, which is considered the best marker of exposure for both. Therefore, tacrolimus AUC0-24h can be estimated by Bayesian estimation using samples collected before administration (C0), 8 (C8h) and 12 (C12h) hours after the administration of ENVARSUS XR®, or 1 and 3 hours after the administration of PROGRAF® and ADVAGRAF®. For mycophenolate, the MPA AUC can be estimated using samples collected 20 min, 1 and 3 hours after MMF administration, by Bayesian estimation.

Even if limited to 2 or 3 blood samples, tacrolimus TDM for ENVARSUS® requires late sampling (12h post-dose). To overcome the necessity of a longer hospital stay, microsampling devices (MSD) such as the Volumetric absorptive microsampling (VAMS®) device (Mitra®) can be used by the patients to take samples themselves, at home. Moreover, they are less invasive than venipuncture and collect low but accurate volumes of blood for analysis.

In this context, we propose a randomized controlled non-inferiority study to demonstrate that in liver transplant recipients, an immunosuppressive strategy based on single daily doses of LCP-tacrolimus (ENVARSUS XR®) and mycophenolate mofetil (CELLCEPT®) started at M6 post-transplantation is not inferior to XR-tacrolimus (ADVAGRAF®) and MMF administered BID, in terms of incidence of treatment failure (see below) at the end of the first year after transplantation, and to obtain adherence, quality of life and safety data. In order to compare solely MMF QD to MMF BID, patients on ENVARSUS XR® and MMF QD will be compared to a third group of patients receiving ENVARSUS XR® and MMF BID. A direct comparison of efficacy and safety, quality of life, adherence and exposure indices will be performed between ENVARSUS XR® and ADVAGRAF®.