Desensitization of highly pre-sensitized dialysis patients waiting for kidney transplantation by Rituximab, IVIG-L and rescue Plasmapheresis
THE DRIP STUDY

A substantial part of dialysis patients awaiting transplantation possesses anti
HLA antibodies. In the Netherlands 14% of the renal transplant candidates are
pre-sensitized with a varying range of 5 to 85% panel reactivity. Sensitization
occurs after blood transfusion, pregnancy or following previous
transplantation. These allo-antibodies are a substantial obstacle to the
transplantability with subsequent deleterious socioeconomic consequences. In
addition, after transplantation these allo-antibodies have a negative effect on
both short- and long-term graft survival.
Highly pre-sensitized recipients have a prolonged waiting time for
transplantation, due to difficulties in finding a crossmatch negative donor
organ. For some, the chances of finding such an organ are almost nihil.
Increased waiting time for renal transplantation is associated with increased
morbidity. Several strategies are employed to find a matching organ for
sensitized candidates. Two modes of desensitization therapy have been applied
which are discussed in detail further (Modes of desensitization). These include
the plasmapheresis (PP)/low dose IVIG protocol (Johns Hopkins and Mayo Clinic
Protocol) and the high-dose IVIG protocol (Cedars-Sinai Protocol). Other
approaches involve the The Acceptable Mismatch Program and The Cross Over
Exchange Program. Strategies based on identification of acceptable
HLA-mismatches (AM) result in available kidneys for approximately 60% of these
patients. Currently, the Dutch AM waiting list contains 99 broadly
allo-immunized patients waiting more than 2 years for a crossmatch negative
cadaveric kidney. Among these patients are approximately 20 with current PRA
values of >=80%. For these patients the chance of transplantation within
another 2 years is negligible.
Here, we present the Dutch desensitization protocol, involving candidates for a
cadaveric kidney with a current PRA >=80 % who are on the list of AM Program for
longer than 2 years. Only heart beating donors will be accepted. Highly
sensitized candidates for a living donor will be excluded considering the
operating Cross-Over Transplant Program which can offer these candidates a
higher chance to find a crossmatch negative donor organ.
Modes of desensitization
Intravenous immunoglobulins (IVIG):
In theory, administration of IVIG can both remove and diminish the synthesis of
allo-antibodies. IVIG contains polyclonal, mostly IgG antibodies, prepared from
plasma of human blood donors. These preparations contain antibodies against a
whole array of antigens amongst others antibody idiotypes, CD40, HLA-class I
and II antigens, interleukin 1α and β and interferon-γ. The workingmechanisms
on immune modulation are complex and various and affect both T and B cell
function. Several studies have been published in which IVIG are used to
desensitise highly immunized recipients. These studies were all open and
non-randomized. They varied greatly in timing of the IVIG infusion, the
administered dose, and the additional immunosuppressive therapy. Currently, two
protocols have emerged. These include the plasmapheresis/low dose IVIG protocol
(Johns Hopkins and Mayo Clinic Protocol) and the high-dose IVIG protocol
(Cedars-Sinai Protocol). Briefly, Johns Hopkins and Mayo Clinic Protocol
consists of daily 1-plasma volume exchange using 5% albumin followed by
administration of IVIG (100 mg/kg) in order to achieve a negative Cross Match
Test (CMX). Therefore the number of pre-transplant PP in this protocol can vary
greatly. In addition, patients undergo several PP/IVIG courses on
post-operative days. Cedars-Sinai Protocol utilizes four monthly high dose IVIG
(2g/kg, maximal dose of 140 g) administrations in order to achieve a negative
CDC CMX. Patients continue with one additional high dose IVIG one month after
transplantation. To be enrolled, patients should show some degree of inhibition
in their so-called *in vitro IVIG inhibition CMX test* . Using this protocol
Jordan et al evaluated 77 highly sensitized patients who had positive CMX tests
with their potential donors in the IVIG-PRA test system. Desensitization was in
97% of the patients successful and 87% could be transplanted.
B-cell targeted therapy (Rituximab):
In order to prevent de novo allo-antibody synthesis and circumvent the
production of newly formed (long lived) plasma cells, CD20 positive (naive and
memory) B-cells can be targeted by rituximab (RTX); the up to now most specific
B-cell targeting drug. Rituximab (MabThera; Roche) is a chimeric IgG1 kappa
monoclonal antibody that causes B lymphocyte depletion by means of complement
dependent cytotoxicity, antibody dependent cellular cytotoxicity and direct
induction of apoptosis. RTX has been widely used in the treatment of human B
cell malignancies and autoimmune diseases. B-cell depletion, induced by RTX is
typically followed by a B-cell recovery after 6-9 months. Preliminary studies
indicate that RTX decreases the concentration of pre-existing and
post-transplantation antibodies. Vieira et al described encouraging results
from a phase I clinical trial of RTX in pre-sensitized recipients who are
awaiting a renal transplant. The study showed that RTX could be safely
administered to recipients with dialysis dependent end stage renal disease. It
showed some efficacy in the inhibition of presumed pre-existing memory B cells
and long-lived plasma cells. RTX is also successfully used in the
preconditioning regimen in AB0 incompatible renal allograft recipients.

1. Primary end point is achievement of a negative cross-match test with the
donor kidney and transplantability.
2. Secondary objectives are patient and graft survival, graft function as
assessed by calculated creatinine clearance, proteinuria, the number and
severity of acute (antibody mediated) rejections, blood pressure
(antihypertensive treatment), monitoring of infections and the occurrence of
malignancies.

Prospective clinical observational trial

Description of the treatment protocol:

-Administration of Rituximab (two doses)
The first dose of rituximab (MabThera, Roche) 375 mg/m2 intravenously will be
administered five months prior to transplantation. The second and last dose
will be administered before transplantation and after the completion of a
successful treatment course with 4 doses of monthly IVIG administrations (see
below) and at the time-point at which the patient can indeed be transplanted.
We expect that the patient can indeed be transplanted up to 6 weeks after
completion of desentizisation therapy.
Initial infusion: Start rate of 50 mg/hour; if there are no adverse side
effects; increase the rate 50 mg/hour every 30 minutes, to a maximum of 400
mg/hour. Subsequent infusions: Start at 100 mg/hour; if it is safe; increase
the rate 100 mg/hour every 30 minutes, to a maximum of 400 mg/hour. All
recipients will be given acetaminophen (1000 mg) and Di-adresoneF (25 mg),
tavegil (2 mg), 30 min before the infusion.
-Administration of IVIG-L
Four monthly doses of IVIG-L will be administered prior to the transplantation
in a dose of 2 g/kg with a maximum of 140 gram per treatmentsession, in a
dilute low-osmolaric solution, which can be repeated monthly in case of
prolonged waiting time for a matched donor kidney. IVIG-L administration will
be started at a speed of 30 ml/hr during the first 15 minutes. IVIG-L can be
infused with infusion rates up to 8 ml/min (7 ml/kg/hr) without occurrence of
severe side effects (Sanquin Clinical Study Report KB 97003B). In case of minor
side effects, infusion will be withhold and after full clinical recovery of
symptoms restarted at 50% of the original speed. To avoid the risk of
overhydration in haemodialysis patients, IVIG-L has to be given during dialysis
in a 4-hr period and if necessary continued thereafter (dependent on the total
dose which has to be infused), or otherwise IVIG-L infusion can be started on a
not-dialysis day (dependent on the cardiovascular status of the patient and
under clinical surveillance) followed by dialysis thereafter.
Briefly, IVIG-L (2 g/kg; maximum dose: 140 g) will be administered, on dialysis
or the day after, monthly maximally for 4 months with the last course one month
before transplantation. If the patient who has completed the full desensitizing
treatment course has to wait longer than 4 weeks in order to find a cross match
negative organ , then another IVIG-L dose should be administered.
Plasmapheresis (PP)
If treatment consisting of the first dose of rituximab and the full IVIG-L
course of four monthly doses fail to achieve an acceptable low PRA (lower than
or equal with 5%) and a negative CMX against the primarily unacceptable
antigens, the patients can not be considered for transplantation. In this case
we will institute a *rescue plasmapheresis* protocol encompassing maximal 7
courses of daily large volume pheresis (40 ml/kg body weight) substituting
plasma with saline/albumin solution in order to remove the antibodies as it is
known that a part of these patients can still respond to PP. If this occurs,
the second dose of rituximab will be administered according to the protocol
before tarnsplantation. After each third pheresis, plasma will be substituted
with fresh frozen plasma (FFPs) in order to prevent and minimize the risk of
bleeding.
-Transplantation
Whenever a substantial decrease of HLA-alloantibodies (PRA,lower than or equal
with 5%) is reached with this regimen and a negative crossmatch against a
(selected) cell panel is obtained, transplantation has to be carried out as
soon as possible. The kidney allograft will be allocated according to the
already known acceptable antigen profile for each individual patient and
avoiding DR mismatches. Modification of the AM-status means that only
acceptable HLA-antigen profile which is achieved after rituximab/IVIG-L/PP are
taken into account before allocation takes place. Transplantation will be
performed only in the case of a negative current cross-match test with the
selected donor. Only heart beating donors will be accepted.

Nature and extent of the burden and risks:

Side effects are that of the study medication. Both IVIG-L and Rituximab are
registered drugs in Europe and USA. In USA these medication are used for the
same objectives as discussed in this study (see references in protocol and in
section " additional remarks"). These drugs seemed to be safe and effective in
our target group; namely the dialysis patients. The spectrum of their side
effects comprises undesired evens ranged from allergic reactions to increased
risk of overhydration. The patients will be admitted during these therapeutic
interventions and dialysed extra if necessary.

Benefit is of course the possibility of kidney transplantation. The chances for
this group of patients; waiting longer than two years for a kidney transplant
with a PRA level >=80% is nihil. Each kind of dialysis is accompanied by
increased risk of morbidity and mortality. Moreover, transplantation is the
most cost effective kind of renal function replacement therapy.