CLINICAL PHARMACOLOGY
Mechanism Of Action
Belatacept, a selective T-cell (lymphocyte) costimulation blocker, binds to CD80 and
CD86 on antigen-presenting cells thereby blocking CD28 mediated costimulation of
T lymphocytes. In vitro, belatacept inhibits T lymphocyte proliferation and the
production of the cytokines interleukin-2, interferon-γ, interleukin-4, and TNF-α.
Activated T lymphocytes are the predominant mediators of immunologic rejection.
In non-human primate models of renal transplantation, belatacept monotherapy
prolonged graft survival and decreased the production of anti-donor antibodies,
compared to vehicle.
Pharmacodynamics
Belatacept-mediated costimulation blockade results in the inhibition of cytokine
production by T cells required for antigen-specific antibody production by B cells.
In clinical trials, greater reductions in mean immunoglobulin (IgG, IgM, and IgA)
concentrations were observed from baseline to Month 6 and Month 12 post-transplant
in belatacept-treated patients compared to cyclosporine-treated patients. In an
exploratory subset analysis, a trend of decreasing IgG concentrations with increasing
belatacept trough concentrations was observed at Month 6. Also in this exploratory
subset analysis, belatacept-treated patients with CNS PTLD, CNS infections including
PML, other serious infections, and malignancies were observed to have a higher
incidence of IgG concentrations below the lower limit of the normal range (<694 mg/dL)
at Month 6 than those patients who did not experience these adverse events. This
observation was more pronounced with the higher than recommended dose of
belatacept. A similar trend was also observed for cyclosporine-treated patients with
serious infections and malignancies.
However, it is unclear whether any causal relationship between an IgG concentration
below the lower level of normal and these adverse events exists, as the analysis may
have been confounded by other factors (e.g., age greater than 60 years, receipt of an
extended criteria donor kidney, exposure to lymphocyte depleting agents) which were
also associated with IgG below the lower level of normal at Month 6 in these trials.
Pharmacokinetics
Table 5 summarizes the pharmacokinetic parameters of belatacept in healthy adult
subjects after a single 10 mg per kg intravenous infusion; and in kidney transplant
patients after the 10 mg per kg intravenous infusion at Week 12, and after 5 mg per kg
intravenous infusion every 4 weeks at Month 12 post-transplant or later.
Table 5: Pharmacokinetic Parameters (Mean ± SD [Range]) of Belatacept in
Healthy Subjects and Kidney Transplant Patients After 5 and 10 mg
per kg Intravenous Infusions Administered Over 30 Minutes
Pharmacokinetic
Parameter |
Healthy Subjects
(After 10 mg per kg
Single Dose)
N=15 |
Kidney Transplant
Patients
(After 10 mg per kg
Multiple Doses)
N=10 |
Kidney Transplant
Patients
(After 5 mg per kg
Multiple Doses)
N=14 |
Peak concentration
(Cmax) [μg/mL] |
300 ± 77
(190-492) |
247 ± 68
(161-340) |
139 ± 28
(80-176) |
AUC*
[μg•h/mL] |
26398 ± 5175
(18964-40684) |
22252 ± 7868
(13575-42144) |
14090 ± 3860
(7906-20510) |
Terminal half-life
(t1/2) [days] |
9.8 ± 2.8
(6.4-15.6) |
9.8 ± 3.2
(6.1-15.1) |
8.2 ± 2.4
(3.1-11.9) |
Systemic clearance
(CL) [mL/h/kg] |
0.39 ± 0.07
(0.25-0.53) |
0.49 ± 0.13
(0.23-0.70) |
0.51 ± 0.14
(0.33-0.75) |
Volume of distribution
(Vss) [L/kg] |
0.09 ± 0.02
(0.07-0.15) |
0.11 ± 0.03
(0.067-0.17) |
0.12 ± 0.03
(0.09-0.17) |
* AUC=AUC (INF) after single dose and AUC (TAU) after multiple dose, where TAU=4 weeks |
In healthy subjects, the pharmacokinetics of belatacept was linear and the exposure
to belatacept increased proportionally after a single intravenous infusion dose of 1 to
20 mg per kg. The pharmacokinetics of belatacept in de novo kidney transplant
patients and healthy subjects are comparable. Following the recommended regimen,
the mean belatacept serum concentration reached steady-state by Week 8 in the
initial phase following transplantation and by Month 6 during the maintenance phase.
Following once monthly intravenous infusion of 10 mg per kg and 5 mg per kg, there
was about 20% and 10% systemic accumulation of belatacept in kidney transplant
patients, respectively.
Based on population pharmacokinetic analysis of 924 kidney transplant patients up
to 1 year post-transplant, the pharmacokinetics of belatacept were similar at different
time periods post-transplant. In clinical trials, trough concentrations of belatacept
were consistently maintained from Month 6 up to 3 years post-transplant. Population
pharmacokinetic analyses in kidney transplant patients revealed that there was a
trend toward higher clearance of belatacept with increasing body weight. Age, gender,
race, renal function (measured by calculated glomerular filtration rate [GFR]), hepatic
function (measured by albumin), diabetes, and concomitant dialysis did not affect the
clearance of belatacept.
Drug Interactions
Mycophenolate Mofetil
In a pharmacokinetic substudy of Studies 1 and 2, the plasma concentrations of MPA
were measured in 41 patients who received fixed MMF doses of 500 to 1500 mg twice
daily with either 5 mg per kg of NULOJIX or cyclosporine. The mean dose-normalized
MPA Cmax and AUC0-12 were approximately 20% and 40% higher, respectively,
with NULOJIX coadministration than with cyclosporine coadministration [see DRUG INTERACTIONS].
Cytochrome P450 Substrates
The potential of NULOJIX to alter the systemic concentrations of drugs that are
CYP450 substrates was investigated in healthy subjects following administration
of a cocktail of probe drugs given concomitantly with, and at 3 days and at 7 days
following a single intravenous 10 mg per kg dose of NULOJIX. NULOJIX did not alter the
pharmacokinetics of drugs that are substrates of CYP1A2 (caffeine), CYP2C9 (losartan),
CYP2D6 (dextromethorphan), CYP3A (midazolam), and CYP2C19 (omeprazole) [see DRUG INTERACTIONS].
Animal Toxicology And/Or Pharmacology
Abatacept, a fusion protein that differs from belatacept by 2 amino acids, binds to
the same ligands (CD80/CD86) and blocks T-cell costimulation like belatacept, but is
more active than belatacept in rodents. Therefore, toxicities identified with abatacept
in rodents may be predictive of adverse effects in humans treated with belatacept.
Studies in rats exposed to abatacept have shown immune system abnormalities
including a low incidence of infections leading to death (observed in juvenile rats
and pregnant rats) as well as autoimmunity of the thyroid and pancreas (observed in
rats exposed in utero, as juveniles or as adults). Studies of abatacept in adult mice
and monkeys, as well as belatacept in adult monkeys, have not demonstrated similar
findings.
The increased susceptibility to opportunistic infections observed in juvenile rats is
likely associated with the exposure to abatacept before the complete development
of memory immune responses. In pregnant rats, the increased susceptibility to
opportunistic infections may be due to the inherent lapses in immunity that occur
in rats during late pregnancy/lactation. Infections related to NULOJIX have been
observed in human clinical trials [see WARNINGS AND PRECAUTIONS].
Administration of abatacept to rats was associated with a significant decrease in
T-regulatory cells (up to 90%). Deficiency of T-regulatory cells in humans has been
associated with autoimmunity. The occurrence of autoimmune events across the
core clinical trials was infrequent. However, the possibility that patients administered
NULOJIX could develop autoimmunity (or that fetuses exposed to NULOJIX in utero
could develop autoimmunity) cannot be excluded.
In a 6-month toxicity study with belatacept in cynomolgus monkeys administered
weekly doses up to 50 mg per kg (6 times the MRHD exposure) and in a 1-year toxicity
study with abatacept in adult cynomolgus monkeys administered weekly doses up
to 50 mg per kg, no significant drug-related toxicities were observed. Reversible
pharmacological effects consisted of minimal transient decreases in serum IgG and
minimal to severe lymphoid depletion of germinal centers in the spleen and/or lymph
nodes.
Following 5 doses (10 mg per kg or 50 mg per kg, once a week for 5 weeks) of
systemic administration, belatacept was not detected in brain tissue of normal healthy
cynomolgus monkeys. The number of cells expressing major histocompatibility
complex (MHC) class-II antigens (potential marker of immune cell activation) in the
brain were increased in monkeys administered belatacept compared to vehicle
control. However, distribution of some other cells expressing CD68, CD20, CD80, and
CD86, typically expressed on MHC class II-positive cells, was not altered and there
were no other histological changes in the brain. The clinical relevance of the findings
is unknown.
Clinical Studies
Prevention Of Organ Rejection In Kidney Transplant Recipients
The efficacy and safety of NULOJIX in de novo kidney transplantation were assessed
in two open-label, randomized, multicenter, active-controlled trials (Study 1 and
Study 2). These trials evaluated two dose regimens of NULOJIX, the recommended
dosage regimen [see DOSAGE AND ADMINISTRATION] and a regimen with higher
cumulative doses and more frequent dosing than the recommended dosage regimen,
compared to a cyclosporine control regimen. All treatment groups also received
basiliximab induction, mycophenolate mofetil (MMF), and corticosteroids.
Treatment Regimen
The NULOJIX recommended regimen consisted of a 10 mg per kg dose administered
on Day 1 (the day of transplantation, prior to implantation), Day 5 (approximately
96 hours after the Day 1 dose), end of Weeks 2 and 4; then every 4 weeks through
Week 12 after transplantation. Starting at Week 16 after transplantation, NULOJIX
was administered at the maintenance dose of 5 mg per kg every 4 weeks (plus
or minus 3 days). NULOJIX was administered as an intravenous infusion over
30 minutes [see DOSAGE AND ADMINISTRATION] .
Basiliximab 20 mg was administered intravenously on the day of transplantation and
4 days later.
The initial dose of MMF was 1 gram twice daily and was adjusted, as needed based on
clinical signs of adverse events or efficacy failure.
The protocol-specified dosing of corticosteroids in Studies 1 and 2 at Day 1 was
methylprednisolone (as sodium succinate) 500 mg IV on arrival in the operating room,
Day 2, methylprednisolone 250 mg IV, and Day 3, prednisone 100 mg orally. Actual
median corticosteroid doses used with the NULOJIX recommended regimen from
Week 1 through Month 6 are summarized in the table below (Table 6).
Table 6: Actual Corticosteroid* Dosing in Studies 1 and 2
Day of Dosing |
Median (Q1–Q3) Daily Dose†,‡ |
Study 1 |
Study 2 |
Week 1 |
31.7 mg
(26.7-50 mg) |
30 mg
(26.7-50 mg) |
Week 2 |
25 mg
(20-30 mg) |
25 mg
(20-30 mg) |
Week 4 |
20 mg
(15-20 mg) |
20 mg
(15-22.5 mg) |
Week 6 |
15 mg
(10-20 mg) |
16.7 mg
(12.5-20 mg) |
Month 6 |
10 mg
(5-10 mg) |
10 mg
(5-12.5 mg) |
* Corticosteroid = prednisone or prednisolone.
† The protocols allowed for flexibility in determining corticosteroid dose and rapidity
of taper after Day 15. It is not possible to distinguish corticosteroid doses used to
treat acute rejection versus doses used in a maintenance regimen.
‡ Q1 and Q3 are the 25th and 75th percentiles of daily corticosteroid doses,
respectively. |
Study 1 enrolled recipients of living donor and standard criteria deceased donor organs
and Study 2 enrolled recipients of extended criteria donor organs. Standard criteria
donor organs were defined as organs from a deceased donor with anticipated cold
ischemia time of <24 hours and not meeting the definition of extended criteria donor
organs. Extended criteria donors were defined as deceased donors with at least one
of the following: (1) donor age ≥60 years; (2) donor age ≥50 years and other donor
comorbidities (≥2 of the following: stroke, hypertension, serum creatinine >1.5 mg/dL);
(3) donation of organ after cardiac death; or (4) anticipated cold ischemia time of the
organ of ≥24 hours. Study 1 excluded recipients undergoing a first transplant whose
current Panel Reactive Antibodies (PRA) were ≥50% and recipients undergoing a
retransplantation whose current PRA were ≥30%; Study 2 excluded recipients with a
current PRA ≥30%. Both studies excluded recipients with HIV, hepatitis C, or evidence
of current hepatitis B infection; recipients with active tuberculosis; and recipients in
whom intravenous access was difficult to obtain.
Efficacy data are presented for the NULOJIX recommended regimen and cyclosporine
regimen in Studies 1 and 2.
The NULOJIX regimen with higher cumulative doses and more frequent dosing of
belatacept was associated with more efficacy failures. Higher doses and/or more
frequent dosing of NULOJIX are not recommended [see DOSAGE AND ADMINISTRATION
, WARNINGS AND PRECAUTIONS and ADVERSE REACTIONS].
Study 1: Recipients Of Living Donor And Standard Criteria Deceased Donor
Kidneys
In Study 1, 666 patients were enrolled, randomized, and transplanted: 226 to the
NULOJIX recommended regimen, 219 to the NULOJIX regimen with higher cumulative
doses and more frequent dosing than recommended, and 221 to cyclosporine control
regimen. The median age was 45 years; 58% of organs were from living donors;
3% were re-transplanted; 69% of the study population was male; 61% of patients
were white, 8% were black/African-American, 31% were categorized as of other
races; 16% had PRA ≥10%; 41% had 4 to 6 HLA mismatches; and 27% had diabetes
prior to transplant. The incidence of delayed graft function was similar in all treatment
arms (14% to 18%).
Premature discontinuation from treatment at the end of the first year occurred in
19% of patients receiving the NULOJIX recommended regimen and 19% of patients
on the cyclosporine regimen. Among the patients who received the NULOJIX
recommended regimen, 10% discontinued due to lack of efficacy, 5% due to adverse
events, and 4% for other reasons. Among the patients who received the cyclosporine
regimen, 9% discontinued due to adverse events, 5% due to lack of efficacy, and 5%
for other reasons.
At the end of three years, 25% of patients receiving the NULOJIX recommended
regimen and 34% of patients receiving the cyclosporine regimen had discontinued
from treatment. Among the patients who received the NULOJIX recommended regimen,
12% discontinued due to lack of efficacy, 7% due to adverse events, and 6% for other
reasons. Among the patients who received the cyclosporine regimen, 15% discontinued
due to adverse events, 8% due to lack of efficacy, and 11% for other reasons.
Assessment of Efficacy
Table 7 summarizes the results of Study 1 following one and three years of treatment
with the NULOJIX recommended dosage regimen and the cyclosporine control
regimen. Efficacy failure at one year was defined as the occurrence of biopsy proven
acute rejection (BPAR), graft loss, death, or lost to follow-up. BPAR was defined as
histologically confirmed acute rejection by a central pathologist on a biopsy done for
any reason, whether or not accompanied by clinical signs of rejection. Patient and graft
survival was also assessed separately.
Table 7: Efficacy Outcomes by Years 1 and 3 for Study 1: Recipients of Living
and Standard Criteria Deceased Donor Kidneys
Parameter |
NULOJIX
Recommended
Regimen
N=226
n (%) |
Cyclosporine
(CSA)
N=221
n (%) |
NULOJIX-CSA
(97.3% CI) |
Efficacy Failure by Year 1 |
49 (21.7) |
37 (16.7) |
4.9 (−3.3, 13.2) |
Components of Efficacy Failure* |
Biopsy Proven Acute Rejection |
45 (19.9) |
23 (10.4) |
|
Graft Loss |
5 (2.2) |
8 (3.6) |
|
Death |
4 (1.8) |
7 (3.2) |
|
Lost to follow-up |
0 |
1 (0.5) |
|
Efficacy Failure by Year 3 |
58 (25.7) |
57 (25.8) |
−0.1 (−9.3, 9) |
Components of Efficacy Failure* |
Biopsy Proven Acute Rejection |
50 (22.1) |
31 (14) |
|
Graft Loss |
9 (4) |
10 (4.5) |
|
Death |
10 (4.4) |
15 (6.8) |
|
Lost to follow-up |
2 (0.9) |
5 (2.3) |
|
Patient and graft survival† |
Year 1 |
218 (96.5) |
206 (93.2) |
3.2 (-1.5, 8.4) |
Year 3 |
206 (91.2) |
192 (86.9) |
4.3 (−2.2, 10.8) |
* Patients may have experienced more than one event.
† Patients known to be alive with a functioning graft. |
In Study 1, the rate of BPAR at one year and three years was higher in patients treated
with the NULOJIX recommended regimen than the cyclosporine regimen. Of the patients
who experienced BPAR with NULOJIX, 70% experienced BPAR by Month 3, and 84%
experienced BPAR by Month 6. By three years, recurrent BPAR occurred with similar
frequency across treatment groups (<3%). The component of BPAR determined by biopsy
only (subclinical protocol-defined acute rejection) was 5% in both treatment groups.
Patients treated with the NULOJIX recommended regimen experienced episodes of
BPAR classified as Banff grade IIb or higher (6% [14/226] at one year and 7% [15/226]
at three years) more frequently compared to patients treated with the cyclosporine
regimen (2% [4/221] at one year and 2% [5/221] at three years). Also, T-cell depleting
therapy was used more frequently to treat episodes of BPAR in NULOJIX-treated
patients (10%; 23/226) compared to cyclosporine-treated patients (2%; 5/221).
At Month 12, the difference in mean calculated glomerular filtration rate (GFR) between
patients with and without history of BPAR was 19 mL/min/1.73 m2 among NULOJIXtreated
patients compared to 7 mL/min/1.73 m2 among cyclosporine-treated patients.
By three years, 22% (11/50) of NULOJIX-treated patients with a history of BPAR
experienced graft loss and/or death compared to 10% (3/31) of cyclosporine-treated
patients with a history of BPAR; at that time point, 10% (5/50) of NULOJIX-treated
patients experienced graft loss and 12% (6/50) of NULOJIX-treated patients had died
following an episode of BPAR, whereas 7% (2/31) of cyclosporine-treated patients
experienced graft loss and 7% (2/31) of cyclosporine-treated patients had died
following an episode of BPAR. The overall prevalence of donor-specific antibodies was
5% and 11% for the NULOJIX recommended regimen and cyclosporine, respectively,
up to 36 months post-transplant.
While the difference in GFR in patients with BPAR versus those without BPAR was
greater in patients treated with NULOJIX than cyclosporine, the mean GFR following
BPAR was similar in NULOJIX (49 mL/min/1.73 m2) and cyclosporine treated patients
(43 mL/min/1.73 m2) at one year. The relationship between BPAR, GFR, and patient and
graft survival is unclear due to the limited number of patients who experienced BPAR,
differences in renal hemodynamics (and, consequently, GFR) across maintenance
immunosuppression regimens, and the high rate of switching treatment regimens
after BPAR.
Assessment of Efficacy in the EBV Seropositive Subpopulation
NULOJIX is recommended for use only in EBV seropositive patients [see INDICATIONS].
In Study 1, approximately 87% of patients were EBV seropositive prior to transplant.
Efficacy results in the EBV seropositive subpopulation were consistent with those in
the total population studied.
By one year, the efficacy failure rate in the EBV seropositive population was 21%
(42/202) in patients treated with the NULOJIX recommended regimen and 17%
(31/184) in patients treated with cyclosporine (difference=4%, 97.3% CI [–4.8, 12.8]).
Patient and graft survival was 98% (198/202) in NULOJIX-treated patients and 92%
(170/184) in cyclosporine-treated patients (difference=5.6%, 97.3% CI [0.8, 10.4]).
By three years, efficacy failure was 25% in both treatment groups and patient and
graft survival was 94% (187/202) in NULOJIX-treated patients compared with 88%
(162/184) in cyclosporine-treated patients (difference=4.6%, 97.3% CI [–2.1, 11.3]).
Assessment of Glomerular Filtration Rate (GFR)
Glomerular Filtration Rate (GFR) was measured at one and two years and was calculated
using the Modification of Diet in Renal Disease (MDRD) formula at one, two, and three
years after transplantation. As shown in Table 8, both measured and calculated GFR
was higher in patients treated with the NULOJIX recommended regimen compared to
patients treated with the cyclosporine control regimen at all time points. As shown in
Figure 1, the differences in GFR were apparent in the first month after transplant and
were maintained up to three years (36 months). An analysis of change of calculated
mean GFR between three and 36 months demonstrated an increase of 0.8 mL/min/year
(95% CI [–0.2, 1.8]) for NULOJIX-treated patients and a decrease of 2.2 mL/min/year
(95% CI [–3.2, –1.2]) for cyclosporine-treated patients.
Table 8: Measured and Calculated GFR for Study 1: Recipients of Living and
Standard Criteria Deceased Donor Kidneys
Parameter |
NULOJIX
Recommended
Regimen
N=226 |
Cyclosporine
(CSA)
N=221 |
NULOJIX-CSA
(97.3% CI) |
Measured GFR* mL/min/1.73 m2
mean (SD) |
Year 1 |
63.4 (27.7)
(n=206) |
50.4 (18.7)
(n=199) |
13.0 (7.3, 18.7) |
Year 2† |
67.9 (29.9)
(n=199) |
50.5 (20.5)
(n=185) |
17.4 (11.5, 23.4) |
Calculated GFR‡ mL/min/1.73 m2
mean (SD) |
Year 1 |
65.4 (22.9)
(n=200) |
50.1 (21.1)
(n=199) |
15.3 (10.3, 20.3) |
Year 2 |
65.4 (25.2)
(n=201) |
47.9 (23
(n=182) |
17.5 (12, 23.1) |
Year 3 |
65.8 (27)
(n=190) |
44.4 (23.6)
(n=171) |
21.4 (15.4, 27.4) |
* GFR was measured using the cold-iothalamate method.
† Measured GFR was not assessed at Year 3.
‡ GFR was calculated using the MDRD formula. |
Figure 1: Calculated (MDRD) GFR through Month 36; Study 1: Recipients of
Living and Standard Criteria Deceased Donor Kidneys
Assessment of Chronic Allograft Nephropathy (CAN)
The prevalence of chronic allograft nephropathy (CAN) at one year, as defined by
the Banff ’97 classification system, was 24% (54/226) in patients treated with the
NULOJIX recommended regimen and in 32% (71/219) of patients treated with the
cyclosporine control regimen. CAN was not evaluated after the first year following
transplantation. The clinical significance of this finding is unknown.
Study 2: Recipients Of Extended Criteria Donor Kidneys
In Study 2, 543 patients were enrolled, randomized, and transplanted: 175 to the
NULOJIX recommended regimen, 184 to the NULOJIX regimen with higher cumulative
doses and more frequent dosing than recommended, and 184 to the cyclosporine
control regimen. The median age was 58 years; 67% of the study population was
male; 75% of patients were white, 13% were black/African-American, 12% were
categorized as of other races; 3% had PRA ≥10%; 53% had 4 to 6 HLA mismatches;
and 29% had diabetes prior to transplantation. The incidence of delayed graft function
was similar in all treatment arms (47% to 49%).
Premature discontinuation from treatment at the end of the first year occurred in
25% of patients receiving the NULOJIX recommended regimen and 30% of patients
receiving the cyclosporine control regimen. Among the patients who received the
NULOJIX recommended regimen, 14% discontinued due to adverse events, 9% due
to lack of efficacy, and 2% for other reasons. Among the patients who received the
cyclosporine regimen, 17% discontinued due to adverse events, 7% due to lack of
efficacy, and 6% for other reasons.
At the end of three years, 35% of patients receiving the NULOJIX recommended
regimen and 44% of patients receiving the cyclosporine regimen had discontinued
from treatment. Among the patients who received the NULOJIX recommended regimen,
20% discontinued due to adverse events, 9% due to lack of efficacy, and 6% for other
reasons. Among the patients who received the cyclosporine regimen, 25% discontinued
due to adverse events, 10% due to lack of efficacy, and 10% for other reasons.
Assessment of Efficacy
Table 9 summarizes the results of Study 2 following one and three years of treatment
with the NULOJIX recommended dosage regimen and the cyclosporine control
regimen. Efficacy failure at one year was defined as the occurrence of biopsy proven
acute rejection (BPAR), graft loss, death, or lost to follow-up. BPAR was defined as
histologically confirmed acute rejection by a central pathologist on a biopsy done for
any reason, whether or not accompanied by clinical signs of rejection. Patient and graft
survival was also assessed.
Table 9: Efficacy Outcomes by Years 1 and 3 for Study 2: Recipients of
Extended Criteria Donor Kidneys
Parameter |
NULOJIX
Recommended
Regimen
N=175
n (%) |
Cyclosporine
(CSA)
N=184
n (%) |
NULOJIX-CSA
(97.3% CI) |
Efficacy Failure by Year 1 |
51 (29.1) |
52 (28.3) |
0.9 (−9.7, 11.5) |
Components of Efficacy Failure* |
Biopsy Proven Acute Rejection |
37 (21.1) |
34 (18.5) |
|
Graft Loss |
16 (9.1) |
20 (10.9) |
|
Death |
5 (2.9) |
8 (4.3) |
|
Lost to follow-up |
0 |
2 (1.1) |
|
Efficacy Failure by Year 3 |
63 (36) |
68 (37) |
−1.0 (−12.1, 10.3) |
Components of Efficacy Failure* |
Biopsy Proven Acute Rejection |
42 (24) |
42 (22.8) |
|
Graft Loss |
21 (12) |
23 (12.5) |
|
Death |
15 (8.6) |
17 (9.2) |
|
Lost to follow-up |
1 (0.6) |
5 (2.7) |
|
Patient and graft survival† |
Year 1 |
155 (88.6) |
157 (85.3) |
3.2 (−4.8, 11.3) |
Year 3 |
143 (81.7) |
143 (77.7) |
4.0 (−5.4, 13.4) |
* Patients may have experienced more than one event.
† Patients known to be alive with a functioning graft. |
In Study 2, the rate of BPAR at one year and three years was similar in patients treated
with NULOJIX and cyclosporine. Of the patients who experienced BPAR with NULOJIX,
62% experienced BPAR by Month 3, and 76% experienced BPAR by Month 6. By three
years, recurrent BPAR occurred with similar frequency across treatment groups (<3%).
The component of BPAR determined by biopsy only (subclinical protocol-defined acute
rejection) was 5% in both treatment groups.
A similar proportion of patients in the NULOJIX recommended regimen group
experienced BPAR classified as Banff grade IIb or higher (5% [9/175] at one year
and 6% [10/175] at three years) compared to patients treated with the cyclosporine
regimen (4% [7/184] at one year and 5% [9/184] at three years). Also, T-cell depleting
therapy was used with similar frequency to treat any episode of BPAR in NULOJIXtreated
patients (5% or 9/175) compared to cyclosporine-treated patients (4% or
7/184). At Month 12, the difference in mean calculated GFR between patients with and
without a history of BPAR was 10 mL/min/1.73 m2 among NULOJIX-treated patients
compared to 14 mL/min/1.73 m2 among cyclosporine-treated patients. By three years,
24% (10/42) of NULOJIX-treated patients with a history of BPAR experienced graft loss
and/or death compared to 31% (13/42) of cyclosporine-treated patients with a history
of BPAR; at that time point, 17% (7/42) of NULOJIX-treated patients experienced graft
loss and 14% (6/42) of NULOJIX-treated patients had died following an episode of
BPAR, whereas 19% (8/42) of cyclosporine-treated patients experienced graft loss
and 19% (8/42) of cyclosporine-treated patients had died following an episode of
BPAR. The overall prevalence of donor-specific antibodies was 6% and 15% for the
NULOJIX recommended regimen and cyclosporine, respectively, up to 36 months
post-transplant.
The mean GFR following BPAR was 36 mL/min/1.73 m2 in NULOJIX patients and
24 mL/min/1.73 m2 in cyclosporine-treated patients at one year. The relationship
between BPAR, GFR, and patient and graft survival is unclear due to the limited
number of patients who experienced BPAR, differences in renal hemodynamics (and,
consequently, GFR) across maintenance immunosuppression regimens, and the high
rate of switching treatment regimens after BPAR.
Assessment of Efficacy in the EBV Seropositive Subpopulation
NULOJIX is recommended for use only in EBV seropositive patients [see INDICATIONS].
In Study 2, approximately 91% of the patients were EBV seropositive prior to transplant.
Efficacy results in the EBV seropositive subpopulation were consistent with those in
the total population studied.
By one year, the efficacy failure rate in the EBV seropositive population was 29%
(45/156) in patients treated with the NULOJIX recommended regimen and 28%
(47/168) in patients treated with cyclosporine (difference=0.8%, 97.3% CI [–10.3,
11.9]). Patient and graft survival rate in the EBV seropositive population was 89%
(139/156) in the NULOJIX-treated patients and 86% (144/168) in cyclosporine-treated
patients (difference=3.4%, 97.3% CI [–4.7, 11.5]).
By three years, efficacy failure was 35% (54/156) in NULOJIX-treated patients and
36% (61/168) in cyclosporine-treated patients. Patient and graft survival was 83%
(130/156) in NULOJIX-treated patients compared with 77% (130/168) in cyclosporinetreated
patients (difference=5.9%, 97.3% CI [–3.8, 15.6]).
Assessment of Glomerular Filtration Rate (GFR)
Glomerular Filtration Rate (GFR) was measured at one and two years and was calculated
using the Modification of Diet in Renal Disease (MDRD) formula at one, two, and three
years after transplantation. As shown in Table 10, both measured and calculated GFR
was higher in patients treated with the NULOJIX recommended regimen compared to
patients treated with the cyclosporine control regimen at all time points. As shown in
Figure 2, the differences in GFR were apparent in the first month after transplant and
were maintained up to three years (36 months). An analysis of change of calculated
mean GFR between Month 3 and Month 36 demonstrated a decrease of 0.8 mL/min/year
(95% CI [–1.9, 0.3]) for NULOJIX-treated patients and a decrease of 2.0 mL/min/year
(95% CI [–3.1, .0.8]) for cyclosporine-treated patients.
Table 10: Measured and Calculated GFR for Study 2: Recipients of Extended
Criteria Donor Kidneys
Parameter |
NULOJIX
Recommended
Regimen
N=175 |
Cyclosporine
(CSA)
N=184 |
NULOJIX-CSA
(97.3% CI) |
Measured GFR* mL/min/1.73 m2
mean (SD) |
Year 1 |
49.6 (25.8)
(n=151) |
45.2 (21.1)
(n=154) |
4.3 (−1.5, 10.2) |
Year 2† |
49.7 (23.7)
(n=139) |
45.0 (27.2)
(n=136) |
4.7 (−1.8, 11.3) |
Calculated GFR‡ mL/min/1.73 m2
mean (SD) |
Year 1 |
44.5 (21.8)
(n=158) |
36.5 (21.1)
(n=159) |
8.0 (2.5, 13.4) |
Year 2 |
42.8 (24.1)
(n=158) |
34.9 (21.6)
(n=154) |
8.0 (1.9, 14) |
Year 3 |
42.2 (25.2)
(n=154) |
31.5 (22.1)
(n=143) |
10.7 (4.3, 17.2) |
* GFR was measured using the cold-iothalamate method.
† Measured GFR was not assessed at Year 3.
‡ GFR was calculated using the MDRD formula. |
Figure 2: Calculated (MDRD) GFR through Month 36; Study 2: Recipients of
Extended Criteria Donor Kidneys
Assessment of Chronic Allograft Nephropathy (CAN)
The prevalence of chronic allograft nephropathy (CAN) at one year, as defined by the
Banff ’97 classification system, was 46% (80/174) in patients treated with the NULOJIX
recommended regimen and 52% (95/184) of patients treated with the cyclosporine
control regimen. CAN was not evaluated after the first year following transplantation.
The clinical significance of this finding is unknown.