Tacrolimus monotherapy in immunologically low-risk kidney transplant recipients: a pilot randomized-controlled study.

Kidney transplantation is the treatment of choice for patients with end-stage
kidney disease. Current immunosuppressive drugs have allowed for 5-year patient
survival of approximately 90% [2, 3]. Malignancy and infectious diseases are
feared and well-known side effects of the immunosuppressive burden after
transplantation [4-8]. Attempts to address these issues by lowering the total
immunosuppressive load must be weighed against the risk of rejection. This risk
differs substantially among patients according to HLA matching [9, 10] and
level of panel reactive antibodies (PRA) [11].
Allograft survival diminishes with each extra mismatch on HLA loci of A, B and
DR [12]. A higher PRA correlates with poorer allograft survival [13]. Therefore
lowering of immunosuppressive drugs to improve long-term malignancy and
infection related outcomes should be carried out according to HLA mismatches
and PRA levels.

Calcineurin inhibitors (CNI) have shown superior renal allograft survival over
azathioprine [14, 15], mTOR-inhibitors [16, 17] and MMF [18]. Therefore CNIs
continue to be the cornerstone of immunosuppressive drugs used after solid
organ transplantation. The once daily formulation Advagraf has proven similar
efficacy [19, 20] and better compliance than twice daily formulation [21].

Attempts to minimize TAC based regimens have mainly been carried out after
induction therapy with alemtuzumab irrespective of the immunological status of
the recipient [22-27]. TACmono after this T-cell depleting agent seems safe
[25, 27], although some studies lack a control group [22-24]. Vitko et al.
conducted a large study comparing steroid-free regimens including basiliximab/
TAC (n=153) to triple steroids/ TAC/ MMF (n=147) in the first six months after
transplantation. TACmono patients revealed more BPAR than triple therapy in
this early postoperative period (26.1 vs. 8.2%, p < 0.001).

Therefore a window of opportunity should be determined when to lower the
immunosuppressive regimen, weighing incidence of rejection against cumulative
immunosuppressive load. The risk for acute rejection is highest in the first
six months after transplantation and substantially decreases after 3-6 months
[9, 28, 29].

Other transplantation centers (UMC Maastricht) use CNI monotherapy in selected
patients with a low immunological risk, however randomized controlled trials
are lacking. In addition, there are no data on the immunological consequences
both in vivo and ex vivo of CNI monotherapy. A study powered for superiority
in malignancy and infectious diseases would take a period too long to conduct a
randomized trial. It is not expected that lowering the immunosuppressive load
would lead to superiority in BPAR-free survival, however TACmono is expected to
be better at secondary endpoints (malignancy and infection) and is a more
patient-friendly regimen with once daily administration of an
immunosuppressant. Before a non-inferiority study is to be carried out in
hundreds of kidney transplant recipients, a pilot study could provide for
information on BPAR rate in the control group and allow termination of the
study when a discrepant high rate of BPAR is observed in the TACmono
intervention group.

Therefore we have designed a pilot study in which patients are randomized six
months after kidney transplantation to either minimize their immunosuppressive
regimen to TACmono or to continue standard TAC/ MMF. By studying general and
donor-specific immune responses the rationale behind minimization can be
further explored. The impact of reducing the total immune suppressive burden in
study participants can be assessed in vivo after vaccination [30, 31]. Staining
of the cell surface marker CD137, a member of the tumor necrosis factor-family,
is a novel flow cytometry assay to identify the total pool of circulating
alloreactive T cells [32]. The intervention of discontinuing MMF offers an
opportunity to study the effect of MMF on blood pressure in humans. Animal
models reveal a relationship between T cell infiltration and hypertension, and
a protective effect on blood pressure while on MMF treatment [33-36].
Monotherapy with Advagraf offers patients theoretically a more patient-friendly
regime: MMF is known for its gastrointestinal side effects [37-39] and
monotherapy Advagraf is a truly once-daily immunosuppressive regimen. The
complement-fixating Luminex assay is a promising assay to predict rejection
rates [40-42]. Therefore the presence of DSA (donor specific antibodies) as
detected by Luminex will be analysed in both treatment arms.

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The primary objective of the main non-inferiority study is to determine the
safety of TACmono starting nine months after kidney transplantation in
immunologically low-risk patients in terms of BPAR-rate 15 months after
transplantation compared to dual therapy with TAC and MMF.

First a pilot or feasibility study is needed to investigate the feasibility
objectives:
1. Methodology: Outcome in the control group: what is the BPAR-rate in the
control group?
2. Process: Recruitment rates. How many patients can be included, what is the
rate of consent, determining centre willingness and capacity?
3. Scientific (biological plausibility):
Estimate of the treatment effect using surrogate endpoints is the primary
objective of the pilot study:
Does TACmono provides for better general immune responses than dual therapy as
measured by:
I. Number of cytokine-producing alloreactive CD137+ T-cells
II. Total number of infectious episodes
III. Vaccination response score.


The secondary objectives of the pilot study are:
1. BPAR rate 15 months after kidney transplantation.
2. Assessment of de novo (complement-fixating) alloantibody formation as
detected by Luminex.
3. Kidney allograft function (eGFR with CKD-EPI formula and proteinuria
expressed in urine protein/creatinine ratio).
4. Detection of donor-specific CD137+ T cells.
5. Composition of leucocyte subsets.
6. Blood pressure levels and number of antihypertensive drugs
after discontinuation of MMF as compared to continuation with dual
TAC/MMF therapy.
7. Gastrointestinal symptoms and quality of life outcomes.

Criteria for success of pilot study:
1. A minimum of 40 patients is recruited per group.
2. Consent is given in 70% of eligible patients.
3. The descriptive outcomes in general immune responses provide for a
biological plausible benefit of TACmono over dual therapy.
*

This is a randomized, investigator-driven, open-label, single centre pilot
study. The pilot is conducted to assess the feasibility of a larger
non-inferiority study. The follow-up will be 15 months for the primary and
secondary outcomes. Kidney transplant recipients will be asked for consent in
the first week after kidney transplantation. At day 7, the tacrolimus twice
daily formulation Prograft® is converted to the slow release formulation
Advagraf® with once daily administration.
Six months after transplantation participants are randomized to either continue
dual therapy with TAC and MMF or gradually decrease the MMF to TACmono therapy
at 9 months. TAC trough levels are aimed for 6-8 ng/ml in both groups.
Both groups have received the same *standard of care* regimen till 6 months:
- induction therapy with basiliximab (IL-2 receptor blocker) 20 mg day 0 and 4
- prednisone
o day 0, 1 and 2: 50 mg twice daily intravenously.
o day 3-14: 20 mg once daily
o day 15-28: 15 mg once daily
o month 2: 10 mg once daily
o month 3: 7.5 mg once daily
o month 4-5: tapering from 5 mg once daily to discontinuation month 5.
- tacrolimus targeted trough levels:
o day 0-14: 10-15 microg/l
o day 15-28: 8-12 microg/l
o week 5-12: 6-10 microg/l
o from month 4 onwards: 6-8 microg/l
- mycophenolate mofetil acid: targeted trough levels 1.5-3 mg/l, according to
common practice (not exceeding 1000 mg twice daily).
Patients will be vaccinated against pneumococcus and tetanus at month 12. Three
weeks after vaccination extra blood will be drawn to compare IgG titers after
vaccination with baseline. Influenza vaccination is offered in seasonal
clusters between month 12-15 after transplantation. During regular outpatient
clinic visits, extra blood samples are drawn to study ex vivo immune responses.
Blood pressure levels are monitored with *Datascope* measurements according to
local practice. At months 6, 12 and month 15 patients are asked to fill in
questionnaires about gastrointestinal symptoms and quality of life issues.
To study ex vivo immunological responses against donor cells, donor cells are
either harvested from the spleen after postmortal donation or from blood
samples of living donation donors. Donors are asked for their consent (see
donor PIF) to donate blood (total maximum of 105 ml) during admission or during
the regular outpatient clinic visit.

Six months after kidney transplantation participants are randomised to decrease
MMF and discontinue this drug at nine months, continuing with TACmono
thereafter. The control group receives standard therapy with TAC and MMF.

The risk of the venapunctures is small, as extra blood tubes are taken at time
points when blood is already drawn, except for the blood drawn to measure
vaccination responses. The risk of a venapuncture is the occurrence of a bruise
after puncture and possible pain-symptoms at the site of puncture. Vaccination
can give local reactions the first day(s): pain, redness and swelling. Fever,
malaise, fatigue and headaches are also reported in the first week after
vaccination. Known history of anaphylactic reactions or Guillain-Barré syndrome
in 6 weeks after vaccination is a contra-indication to vaccination. By
participating in this study, patients will have easy access to national and
international recommended vaccinations after transplantation.
Treatment by TACmono has theoretically a greater risk of BPAR. Therefore a time
window for discontinuation at nine months has been chosen. The investigators
and the DSMB will closely monitor BPAR rates. The potential/ theoretical
benefit of treatment by TACmono consists of less infections and less
malignancies. In the intervention group participants have a more
patient-friendly medication regime with only once daily a immunosuppressive
tablet, enhancing compliance.