Clinical Trial Details
— Status: Withdrawn
Administrative data
NCT number |
NCT00476515 |
Other study ID # |
2006P002059 |
Secondary ID |
|
Status |
Withdrawn |
Phase |
Phase 1
|
First received |
|
Last updated |
|
Start date |
March 2007 |
Est. completion date |
September 2007 |
Study information
Verified date |
October 2023 |
Source |
Massachusetts General Hospital |
Contact |
n/a |
Is FDA regulated |
No |
Health authority |
|
Study type |
Interventional
|
Clinical Trial Summary
Primary Objectives:
- Conversion of a positive donor specific cross-match to a living donor to a negative
cross-match thereby allowing successful renal transplantation.
- Transplant success or failure following the desensitization protocol.
- Determination of the effect of rituximab on the kinetics of donor specific antibodies
(DSA).
- Determination of the effect of rituximab on the kinetics of B-cell subpopulations in
peripheral blood and/or secondary lymphoid organs (lymph node biopsies at time of
transplant, if available) in both responders and non-responders using flow cytometry
and/or immunohistochemistry.
Secondary Objectives:
-Decrease in incidence of humoral rejection to less than 50 % at 1 year.
Description:
For patients with a donor specific antibody, a protocol of plasmapheresis and intravenous
immunoglobulin has been used to remove circulating antibodies and suppress antibody
production. While this therapy is effective at enabling transplantation, it has a reported
failure rate of 50% (Personal communication, Johns Hopkins' group); it is expensive (average
cost of protocol $55,000.00 does not include transplant surgery costs; personal
communication: Johns Hopkins' group) and may be fraught with infectious complications
particularly when combined with current immunosuppression protocols.
To date, there is no effective treatment protocol designed to desensitize end stage renal
disease patients with a high Panel of Reactive Antibodies (PRA) (i.e., >70%). Patients with
elevated PRA levels have a longer median organ waiting time when compared to those with lower
PRA. Patients with elevated PRA have decreased allograft survival when compared to controls.
It has been reported that 50% of cadaveric kidneys transplanted into high PRA recipients
(>20%) suffered of rejection within 6 months of transplantation.
Pathophysiologically, an elevated PRA or a donor specific antibody is acquired through the
sensitization of the host against major histocompatibility antigens (HLA) following multiple
blood transfusions, prior pregnancy or organ transplantation. The constant levels of anti-HLA
antibodies are maintained through the persistent stimulation of naïve and memory B-cells by
these antigens. The number of patients with a high PRA and/or donor specific antibodies is
expected to increase as more patients with failed kidney transplants are entering the waiting
list.
Although initially introduced for the treatment of neoplasms, the humoral immunosuppressant
effects of Rituximab have been shown to have clinical significance. In an attempt to
understand the humoral immunosuppressant effects of Rituximab Gonzalez-Stawinski et al.,
reported the effects of the monoclonal on a de-novo and memory humoral immune response. Their
work showed that Rituximab interferes with both primary and secondary humoral responses by
eliminating B-cells prior to antigen exposure thus interfering with differentiation into
antibody secreting cells and specific antibody production (Gonzalez-Stawinski)
Enthusiasm for these data resulted in small, single center experiences using Rituximab in the
post-transplant and pre-transplant settings. Post-transplantation, Becker et al. utilized
Rituximab as rescue therapy in 4 kidney transplant patients who developed acute humoral
rejection. These patients had failed conventional rescue therapy (high dose intravenous
steroids, and plasmapheresis with IVIg), but transplants were salvaged by a single dose of
Rituximab (375mg/M2) as demonstrated by improvements in creatinine clearances. Also in a
post-transplant setting, Samaniego et al. successfully utilized Rituximab in a small
population of highly sensitized renal transplant patients with positive donor specific
crossmatch who failed the standard plasmapheresis and IVIg protocol. Pre-transplantation,
Vieira et al were able to reduce the concentrations of anti-HLA antibodies after the
administration of a single dose of Rituximab. Fifty percent of these patients had their PRA's
decrease by nearly 40% of baseline.
In these small clinical reports, Rituximab has been an effective humoral immunosuppressant
that eliminates the cell population responsible for anti-HLA antibody production by virtue of
the modulation of naïve or memory B-cells prior to/or during HLA stimulation. However, the
effect of a schema of multiple doses of Rituximab on donor specific crossmatch is yet to be
determined.