Evaluation of a Strategy Based on the 3-month Screening Biopsy to Optimize the Immunosuppression in Renal Transplantation: the I4BiS Study

Renal transplantation represents currently the best therapeutic alternative for end-stage renal failure, not only in terms of patient outcomes (better quality of life and longer survival), but also in terms of costs for the society.

Progress achieved in the last 20 years has resulted in a drastic reduction of the incidence of "classic" (i.e. clinically patent) acute cellular rejection episodes.

Unfortunately, and rather unexpectedly, this progress has had hardly any effect on the frequency of the loss of kidney transplants beyond the first year, as shown by the stagnation of grafts' half lives.

Furthermore, the use of immunosuppressant combinations that are more and more powerful has an impact on adverse effects in recipients, including an increased incidence of infections, cancers, but also metabolic complications (diabetes, osteoporosis, dyslipidemia, etc.), which are cause of significant morbi-mortality.

In an attempt to improve on these disappointing outcomes, some teams have offered to perform screening biopsies: i.e. routine biopsies at specific time points during the follow up, irrespective of graft function. Their primary interest is to allow a pathological analysis of the graft at an early stage, i.e. when potential histological lesions allow for a diagnosis but before these lesions impact on graft's function. Indeed, it has been clearly demonstrated that therapeutic adjustments intended to protect the grafts are most effective when introduced early. There is a fairly broad consensus to perform these biopsies three months and one year after the transplantation. Performing screening biopsies has led to the identification of "subclinical" forms of rejection, i.e. graft infiltration by recipient immune effectors meeting the Banff histological criteria, but without increase in creatininemia.

Assuming that about 10% of screening biopsies performed at 3 months reveal a subclinical rejection, which needs to be treated, the management strategy for the remaining 90% of patients, whose biopsies show either i) a mild inflammatory infiltrates: i.e. "borderline changes", or ii) the complete absence of immune effectors in the graft is, poorly standardized.

The investigators therefore propose to conduct a prospective randomized trial to answer these questions simultaneously by evaluating a strategy to optimize the immunosuppression of renal graft recipients based on the presence or absence of subclinical intragraft inflammatory infiltrates in the screening biopsy performed at 3 months post transplantation. Patients with borderline changes (sub-study A) will be randomized to receive a treatment for rejection (corticosteroid boluses). Patients without inflammation in their graft (sub-study B) will be randomized for corticosteroid withdrawal. Impact on graft function, progression of histological lesions and incidence of morbidity will be evaluated.