CLINICAL PHARMACOLOGY
Mechanism Of Action
Sirolimus inhibits T-lymphocyte activation and
proliferation that occurs in response to antigenic and cytokine (Interleukin
[IL]-2, IL-4, and IL-15) stimulation by a mechanism that is distinct from that
of other immunosuppressants. Sirolimus also inhibits antibody production. In
cells, sirolimus binds to the immunophilin, FK Binding Protein-12 (FKBP-12), to
generate an immunosuppressive complex. The sirolimus:FKBP-12 complex has no
effect on calcineurin activity. This complex binds to and inhibits the
activation of the mammalian target of rapamycin (mTOR), a key regulatory
kinase. This inhibition suppresses cytokine-driven T-cell proliferation,
inhibiting the progression from the G1 to the S phase of the cell cycle.
Mammalian target of rapamycin (mTOR) inhibitors such as sirolimus have been
shown in vitro to inhibit production of certain growth factors that may affect
angiogenesis, fibroblast proliferation, and vascular permeability.
Studies in experimental models show that sirolimus
prolongs allograft (kidney, heart, skin, islet, small bowel,
pancreatico-duodenal, and bone marrow) survival in mice, rats, pigs, and/or
primates. Sirolimus reverses acute rejection of heart and kidney allografts in
rats and prolongs the graft survival in presensitized rats. In some studies,
the immunosuppressive effect of sirolimus lasts up to 6 months after
discontinuation of therapy. This tolerization effect is alloantigen-specific.
In rodent models of autoimmune disease, sirolimus
suppresses immune-mediated events associated with systemic lupus erythematosus,
collagen-induced arthritis, autoimmune type I diabetes, autoimmune myocarditis,
experimental allergic encephalomyelitis, graft-versus-host disease, and
autoimmune uveoretinitis.
Lymphangioleiomyomatosis involves lung tissue
infiltration with smooth muscle-like cells that harbor inactivating mutations
of the tuberous sclerosis complex (TSC) gene (LAM cells). Loss of TSC gene
function activates the mTOR signaling pathway, resulting in cellular
proliferation and release of lymphangiogenic growth factors. Sirolimus inhibits
the activated mTOR pathway and thus the proliferation of LAM cells.
Pharmacodynamics
Orally-administered Rapamune, at doses of 2 mg/day and 5
mg/day, significantly reduced the incidence of organ rejection in low-to
moderate-immunologic risk renal transplant patients at 6 months following
transplantation compared with either azathioprine or placebo [see Clinical
Studies]. There was no demonstrable efficacy advantage of a daily
maintenance dose of 5 mg with a loading dose of 15 mg over a daily maintenance
dose of 2 mg with a loading dose of 6 mg. Therapeutic drug monitoring should be
used to maintain sirolimus drug levels within the target-range [see DOSAGE
AND ADMINISTRATION].
Pharmacokinetics
Sirolimus pharmacokinetics activity have been determined
following oral administration in healthy subjects, pediatric patients,
hepatically impaired patients, and renal transplant patients.
The pharmacokinetic parameters of sirolimus in low-to
moderate-immunologic risk adult renal transplant patients following multiple
dosing with Rapamune 2 mg daily, in combination with cyclosporine and
corticosteroids, is summarized in Table 4.
TABLE 4: MEAN ± SD STEADY STATE SIROLIMUS
PHARMACOKINETIC PARAMETERS IN LOW-TO MODERATE-IMMUNOLOGIC RISK ADULT RENAL
TRANSPLANT PATIENTS FOLLOWING RAPAMUNE 2 MG DAILYa,b
|
Multiple Dose (daily dose) |
Solution |
Tablets |
Cmax (ng/mL) |
14.4 ± 5.3 |
15.0 ± 4.9 |
tmax (hr) |
2.1 ± 0.8 |
3.5 ± 2.4 |
AUC (ng•h/mL) |
194 ± 78 |
230 ± 67 |
Cmin (ng/mL)c |
7.1 ± 3.5 |
7.6 ± 3.1 |
CL/F (mL/h/kg) |
173 ± 50 |
139 ± 63 |
a In presence of cyclosporine administered 4
hours before Rapamune dosing.
b Based on data collected at months 1 and 3 post-transplantation.
c Average Cmin over 6 months. |
Whole blood trough sirolimus concentrations, as measured
by LC/MS/MS in renal transplant patients, were significantly correlated with
AUCτ,ss. Upon repeated, twice-daily administration without an initial
loading dose in a multiple-dose study, the average trough concentration of
sirolimus increases approximately 2-to 3-fold over the initial 6 days of
therapy, at which time steady-state is reached. A loading dose of 3 times the
maintenance dose will provide near steady-state concentrations within 1 day in
most patients [see DOSAGE AND ADMINISTRATION, WARNINGS AND
PRECAUTIONS].
Absorption
Following administration of Rapamune Oral Solution, the
mean times to peak concentration (tmax) of sirolimus are approximately 1 hour
and 2 hours in healthy subjects and renal transplant patients, respectively.
The systemic availability of sirolimus is low, and was estimated to be
approximately 14% after the administration of Rapamune Oral Solution. In
healthy subjects, the mean bioavailability of sirolimus after administration of
the tablet is approximately 27% higher relative to the solution. Sirolimus
tablets are not bioequivalent to the solution; however, clinical equivalence
has been demonstrated at the 2 mg dose level. Sirolimus concentrations,
following the administration of Rapamune Oral Solution to stable renal
transplant patients, are dose-proportional between 3 and 12 mg/m².
Food Effects
To minimize variability in sirolimus concentrations, both
Rapamune Oral Solution and Tablets should be taken consistently with or without
food [see DOSAGE AND ADMINISTRATION]. In healthy subjects, a high-fat
meal (861.8 kcal, 54.9% kcal from fat) increased the mean total exposure (AUC)
of sirolimus by 23 to 35%, compared with fasting. The effect of food on the
mean sirolimus Cmax was inconsistent depending on the Rapamune dosage form
evaluated.
Distribution
The mean (± SD) blood-to-plasma ratio of sirolimus was 36
± 18 in stable renal allograft patients, indicating that sirolimus is
extensively partitioned into formed blood elements. The mean volume of
distribution (Vss/F) of sirolimus is 12 ± 8 L/kg. Sirolimus is extensively
bound (approximately 92%) to human plasma proteins, mainly serum albumin (97%),
α1-acid glycoprotein, and lipoproteins.
Metabolism
Sirolimus is a substrate for both CYP3A4 and P-gp.
Sirolimus is extensively metabolized in the intestinal wall and liver and
undergoes counter-transport from enterocytes of the small intestine into the
gut lumen. Inhibitors of CYP3A4 and P-gp increase sirolimus concentrations.
Inducers of CYP3A4 and P-gp decrease sirolimus concentrations [see WARNINGS
AND PRECAUTIONS and DRUG INTERACTIONS]. Sirolimus is extensively
metabolized by O-demethylation and/or hydroxylation. Seven (7) major
metabolites, including hydroxy, demethyl, and hydroxydemethyl, are identifiable
in whole blood. Some of these metabolites are also detectable in plasma, fecal,
and urine samples. Sirolimus is the major component in human whole blood and
contributes to more than 90% of the immunosuppressive activity.
Excretion
After a single dose of [14C] sirolimus oral
solution in healthy volunteers, the majority (91%) of radioactivity was
recovered from the feces, and only a minor amount (2.2%) was excreted in urine.
The mean ± SD terminal elimination half-life (t½) of sirolimus after multiple
dosing in stable renal transplant patients was estimated to be about 62 ± 16
hours.
Sirolimus Concentrations (Chromatographic Equivalent)
Observed In Phase 3 Clinical Studies
The following sirolimus concentrations (chromatographic
equivalent) were observed in phase 3 clinical studies for prophylaxis of organ
rejection in de novo renal transplant patients[see Clinical Studies].
TABLE 5: SIROLIMUS WHOLE BLOOD TROUGH CONCENTRATIONS
OBSERVED IN RENAL TRANSPLANT PATIENTS ENROLLED IN PHASE 3 STUDIES
Patient Population(Study number) |
Treatment |
Year 1 |
Year 3 |
Mean (ng/mL) |
10th - 90th percentiles (ng/mL) |
Mean (ng/mL) |
10th - 90th percentiles (ng/mL) |
Low-to-moderate risk |
Rapamune (2 mg/day) + CsA |
7.2 |
3.6 - 11 |
- |
- |
(Studies 1 & 2) |
Rapamune (5 mg/day) + CsA |
14 |
8 - 22 |
- |
- |
Low-to-moderate risk (Study 3) |
Rapamune + CsA |
8.6 |
5 - 13a |
9.1 |
5.4 - 14 |
Rapamune alone |
19 |
14 - 22a |
16 |
11 - 22 |
High risk (Study 4) |
Rapamune + CsA |
15.7 |
5.4 - 27.3b |
- |
- |
11.8 |
6.2 - 16.9c |
|
|
11.5 |
6.3 - 17.3d |
|
|
a Months 4 through 12
b Up to Week 2; observed CsA Cmin was 217 (56 – 432) ng/mL
c Week 2 to Week 26; observed CsA Cmin range was 174 (71 – 288)
ng/mL
d Week 26 to Week 52; observed CsA Cmin was 136 (54.5 – 218) ng/mL |
The withdrawal of cyclosporine and concurrent increases
in sirolimus trough concentrations to steady-state required approximately 6
weeks. Following cyclosporine withdrawal, larger Rapamune doses were required
due to the absence of the inhibition of sirolimus metabolism and transport by
cyclosporine and to achieve higher target sirolimus trough concentrations
during concentration-controlled administration [see DOSAGE AND
ADMINISTRATION, DRUG INTERACTIONS].
Lymphangioleiomyomatosis
In a clinical trial of patients with
lymphangioleiomyomatosis, the median whole blood sirolimus trough concentration
after 3 weeks of receiving sirolimus tablets at a dose of 2 mg/day was 6.8
ng/mL (interquartile range 4.6 to 9.0 ng/mL; n = 37).
Pharmacokinetics In Specific Populations
Hepatic Impairment
Rapamune was administered as a single, oral dose to
subjects with normal hepatic function and to patients with Child-Pugh
classification A (mild), B (moderate), or C (severe) hepatic impairment.
Compared with the values in the normal hepatic function group, the patients
with mild, moderate, and severe hepatic impairment had 43%, 94%, and 189%
higher mean values for sirolimus AUC, respectively, with no statistically
significant differences in mean Cmax. As the severity of hepatic impairment
increased, there were steady increases in mean sirolimus t½, and decreases in
the mean sirolimus clearance normalized for body weight (CL/F/kg).
The maintenance dose of Rapamune should be reduced by
approximately one third in patients with mild-to-moderate hepatic impairment
and by approximately one half in patients with severe hepatic impairment [see
DOSAGE AND ADMINISTRATION]. It is not necessary to modify the Rapamune
loading dose in patients with mild, moderate, and severe hepatic impairment.
Therapeutic drug monitoring is necessary in all patients with hepatic
impairment [see DOSAGE AND ADMINISTRATION].
Renal Impairment
The effect of renal impairment on the pharmacokinetics of
sirolimus is not known. However, there is minimal (2.2%) renal excretion of the
drug or its metabolites in healthy volunteers. The loading and the maintenance
doses of Rapamune need not be adjusted in patients with renal impairment [see DOSAGE
AND ADMINISTRATION].
Pediatric Renal Transplant Patients
Sirolimus pharmacokinetic data were collected in
concentration-controlled trials of pediatric renal transplant patients who were
also receiving cyclosporine and corticosteroids. The target ranges for trough
concentrations were either 10-20 ng/mL for the 21 children receiving tablets,
or 5-15 ng/mL for the one child receiving oral solution. The children aged 6-11
years (n = 8) received mean ± SD doses of 1.75 ± 0.71 mg/day (0.064 ± 0.018
mg/kg, 1.65 ± 0.43 mg/m²). The children aged 12-18 years (n = 14) received mean
± SD doses of 2.79 ± 1.25 mg/day (0.053 ± 0.0150 mg/kg, 1.86 ± 0.61 mg/m²). At
the time of sirolimus blood sampling for pharmacokinetic evaluation, the
majority (80%) of these pediatric patients received the Rapamune dose at 16
hours after the once-daily cyclosporine dose. See Table 6 below.
TABLE 6: SIROLIMUS PHARMACOKINETIC PARAMETERS (MEAN ±
SD) IN PEDIATRIC RENAL TRANSPLANT PATIENTS (MULTIPLE-DOSE CONCENTRATION
CONTROL)a,b
Age (y) |
n |
Body weight (kg) |
Cmax,ss (ng/mL) |
tmax,ss (h) |
Cmm,ss (ng/mL) |
AUCT,ss (ng•h/mL) |
CL/Fc (mL/h/kg) |
CL/Fc (L/h/m²) |
6-11 |
8 |
27 ± 10 |
22.1 ± 8.9 |
5.88 ± 4.05 |
10.6 ± 4.3 |
356 ± 127 |
214± 129 |
5.4 ± 2.8 |
12-18 |
14 |
52 ± 15 |
34.5 ± 12.2 |
2.7 ± 1.5 |
14.7 ± 8.6 |
466 ± 236 |
136 ± 57 |
4.7 ± 1.9 |
a Rapamune co-administered with cyclosporine
oral solution [MODIFIED] (e.g., Neoral® Oral Solution) and/or cyclosporine
capsules [MODIFIED] (e.g., Neoral® Soft Gelatin Capsules).
b As measured by Liquid Chromatographic/Tandem Mass Spectrometric
Method (LC/MS/MS)
c Oral-dose clearance adjusted by either body weight (kg) or body
surface area (m²). |
Table 7 below summarizes pharmacokinetic data obtained in
pediatric dialysis patients with chronically impaired renal function.
TABLE 7: SIROLIMUS PHARMACOKINETIC PARAMETERS (MEAN ±
SD) IN PEDIATRIC PATIENTS WITH ENDÂSTAGE KIDNEY DISEASE MAINTAINED ON
HEMODIALYSIS OR PERITONEAL DIALYSIS (1, 3, 9, 15 mg/m2 SINGLE
DOSE)*
Age Group (y) |
n |
tmax (h) |
t½ (h) |
CL/F/WT (mL/h/kg) |
5-11 |
9 |
1.1 ± 0.5 |
71 ± 40 |
580 ± 450 |
12-18 |
11 |
0.79 ± 0.17 |
55 ± 18 |
450±232 |
* All subjects received Rapamune Oral Solution. |
Geriatric
Clinical studies of Rapamune did not include a sufficient
number of patients >65 years of age to determine whether they will respond
differently than younger patients. After the administration of Rapamune Oral
Solution or Tablets, sirolimus trough concentration data in renal transplant
patients >65 years of age were similar to those in the adult population 18
to 65 years of age.
Gender
Sirolimus clearance in males was 12% lower than that in
females; male subjects had a significantly longer t½ than did female subjects
(72.3 hours versus 61.3 hours). Dose adjustments based on gender are not
recommended.
Race
In the phase 3 trials for the prophylaxis of organ
rejection following renal transplantation using Rapamune solution or tablets
and cyclosporine oral solution [MODIFIED] (e.g., Neoral® Oral Solution) and/or
cyclosporine capsules [MODIFIED] (e.g., Neoral® Soft Gelatin Capsules) [see
Clinical Studies], there were no significant differences in mean trough
sirolimus concentrations over time between Black (n = 190) and non-Black (n =
852) patients during the first 6 months after transplantation.
Drug-Drug Interactions
Sirolimus is known to be a substrate for both cytochrome
CYP3A4 and P-gp. The pharmacokinetic interaction between sirolimus and
concomitantly administered drugs is discussed below. Drug interaction studies
have not been conducted with drugs other than those described below.
Cyclosporine
Cyclosporine is a substrate and inhibitor of CYP3A4 and
P-gp. Sirolimus should be taken 4 hours after administration of cyclosporine
oral solution (MODIFIED) and/or cyclosporine capsules (MODIFIED). Sirolimus
concentrations may decrease when cyclosporine is discontinued, unless the
Rapamune dose is increased [see DOSAGE AND ADMINISTRATION, DRUG
INTERACTIONS].
In a single-dose drug-drug interaction study, 24 healthy
volunteers were administered 10 mg Rapamune Tablets either simultaneously or 4
hours after a 300-mg dose of Neoral® Soft Gelatin Capsules (cyclosporine
capsules [MODIFIED]). For simultaneous administration, mean Cmax and AUC were
increased by 512% and 148%, respectively, relative to administration of
sirolimus alone. However, when given 4 hours after cyclosporine administration,
sirolimus Cmax and AUC were both increased by only 33% compared with
administration of sirolimus alone.
In a single dose drug-drug interaction study, 24 healthy
volunteers were administered 10 mg Rapamune Oral Solution either simultaneously
or 4 hours after a 300 mg dose of Neoral® Soft Gelatin Capsules (cyclosporine
capsules [MODIFIED]). For simultaneous administration, the mean Cmax and AUC of
sirolimus, following simultaneous administration were increased by 116% and
230%, respectively, relative to administration of sirolimus alone. However,
when given 4 hours after Neoral® Soft Gelatin Capsules (cyclosporine capsules
[MODIFIED]) administration, sirolimus Cmax and AUC were increased by only 37%
and 80%, respectively, compared with administration of Rapamune alone.
In a single-dose cross-over drug-drug interaction study,
33 healthy volunteers received 5 mg Rapamune Oral Solution alone, 2 hours
before, and 2 hours after a 300 mg dose of Neoral® Soft Gelatin Capsules
(cyclosporine capsules [MODIFIED]). When given 2 hours before Neoral® Soft
Gelatin Capsules (cyclosporine capsules [MODIFIED]) administration, sirolimus Cmax
and AUC were comparable to those with administration of sirolimus alone.
However, when given 2 hours after, the mean Cmax and AUC of sirolimus were
increased by 126% and 141%, respectively, relative to administration of
sirolimus alone.
Mean cyclosporine Cmax and AUC were not significantly
affected when Rapamune Oral Solution was given simultaneously or when
administered 4 hours after Neoral® Soft Gelatin Capsules (cyclosporine capsules
[MODIFIED]). However, after multiple-dose administration of sirolimus given 4
hours after Neoral® in renal post-transplant patients over 6 months,
cyclosporine oral-dose clearance was reduced, and lower doses of Neoral® Soft
Gelatin Capsules (cyclosporine capsules [MODIFIED]) were needed to maintain
target cyclosporine concentration.
In a multiple-dose study in 150 psoriasis patients,
sirolimus 0.5, 1.5, and 3 mg/m²/day was administered simultaneously with
Sandimmune® Oral Solution (cyclosporine Oral Solution) 1.25 mg/kg/day. The
increase in average sirolimus trough concentrations ranged between 67% to 86%
relative to when Rapamune was administered without cyclosporine. The
intersubject variability (% CV) for sirolimus trough concentrations ranged from
39.7% to 68.7%. There was no significant effect of multiple-dose sirolimus on
cyclosporine trough concentrations following Sandimmune® Oral Solution
(cyclosporine oral solution) administration. However, the % CV was higher
(range 85.9% -165%) than those from previous studies.
Diltiazem
Diltiazem is a substrate and inhibitor of CYP3A4 and
P-gp; sirolimus concentrations should be monitored and a dose adjustment may be
necessary [see DRUG INTERACTIONS]. The simultaneous oral administration
of 10 mg of sirolimus oral solution and 120 mg of diltiazem to 18 healthy
volunteers significantly affected the bioavailability of sirolimus. Sirolimus
Cmax, tmax, and AUC were increased 1.4-, 1.3-, and 1.6-fold, respectively.
Sirolimus did not affect the pharmacokinetics of either diltiazem or its
metabolites desacetyldiltiazem and desmethyldiltiazem.
Erythromycin
Erythromycin is a substrate and inhibitor of CYP3A4 and
P-gp; co-administration of sirolimus oral solution or tablets and erythromycin
is not recommended [see WARNINGS AND PRECAUTIONS, DRUG INTERACTIONS].
The simultaneous oral administration of 2 mg daily of sirolimus oral solution
and 800 mg q 8h of erythromycin as erythromycin ethylsuccinate tablets at
steady state to 24 healthy volunteers significantly affected the
bioavailability of sirolimus and erythromycin. Sirolimus Cmax and AUC were
increased 4.4-and 4.2-fold respectively and tmax was increased by 0.4 hr.
Erythromycin Cmax and AUC were increased 1.6-and 1.7-fold, respectively, and
tmax was increased by 0.3 hr.
Ketoconazole
Ketoconazole is a strong inhibitor of CYP3A4 and P-gp;
co-administration of sirolimus oral solution or tablets and ketoconazole is not
recommended [see WARNINGS AND PRECAUTIONS, DRUG INTERACTIONS].
Multiple-dose ketoconazole administration significantly affected the rate and
extent of absorption and sirolimus exposure after administration of Rapamune
Oral Solution, as reflected by increases in sirolimus Cmax, tmax, and AUC of
4.3-fold, 38%, and 10.9-fold, respectively. However, the terminal t½ of
sirolimus was not changed. Single-dose sirolimus did not affect steady-state
12-hour plasma ketoconazole concentrations.
Rifampin
Rifampin is a strong inducer of CYP3A4 and P-gp;
co-administration of Rapamune oral solution or tablets and rifampin is not
recommended. In patients where rifampin is indicated, alternative therapeutic
agents with less enzyme induction potential should be considered [see
WARNINGS AND PRECAUTIONS, DRUG INTERACTIONS]. Pretreatment of 14
healthy volunteers with multiple doses of rifampin, 600 mg daily for 14 days,
followed by a single 20-mg dose of sirolimus oral solution, greatly decreased
sirolimus AUC and Cmax by about 82% and 71%, respectively.
Verapamil
Verapamil is a substrate and inhibitor of CYP3A4 and
P-gp; sirolimus concentrations should be monitored and a dose adjustment may be
necessary; [see DRUG INTERACTIONS]. The simultaneous oral administration
of 2 mg daily of sirolimus oral solution and 180 mg q 12h of verapamil at
steady state to 25 healthy volunteers significantly affected the
bioavailability of sirolimus and verapamil. Sirolimus Cmax and AUC were
increased 2.3-and 2.2-fold, respectively, without substantial change in tmax.
The Cmax and AUC of the pharmacologically active S(-) enantiomer of verapamil
were both increased 1.5-fold and tmax was decreased by 1.2 hr.
Drugs Which May Be Co-administered Without Dose
Adjustment
Clinically significant pharmacokinetic drug-drug
interactions were not observed in studies of drugs listed below. Sirolimus and
these drugs may be co-administered without dose adjustments.
- Acyclovir
- Atorvastatin
- Digoxin
- Glyburide
- Nifedipine
- Norgestrel/ethinyl estradiol (Lo/Ovral®)
- Prednisolone
- Sulfamethoxazole/trimethoprim (Bactrim®)
Other Drug-Drug Interactions
Co-administration of Rapamune with other known strong
inhibitors of CYP3A4 and/or P-gp (such as voriconazole, itraconazole,
telithromycin, or clarithromycin) or other known strong inducers of CYP3A4
and/or P-gp (such as rifabutin) is not recommended [see WARNINGS AND
PRECAUTIONS, DRUG INTERACTIONS]. In patients in whom strong
inhibitors or inducers of CYP3A4 are indicated, alternative therapeutic agents
with less potential for inhibition or induction of CYP3A4 should be considered.
Care should be exercised when drugs or other substances
that are substrates and/or inhibitors or inducers of CYP3A4 are administered
concomitantly with Rapamune. Other drugs that have the potential to increase
sirolimus blood concentrations include (but are not limited to):
- Calcium channel blockers: nicardipine.
- Antifungal agents: clotrimazole, fluconazole.
- Antibiotics: troleandomycin.
- Gastrointestinal prokinetic agents: cisapride, metoclopramide.
- Other drugs: bromocriptine, cimetidine, danazol, protease
inhibitors (e.g., for HIV and hepatitis C that include drugs such as ritonavir, indinavir,
boceprevir, and telaprevir).
Other drugs that have the potential to decrease sirolimus
concentrations include (but are not limited to):
- Anticonvulsants: carbamazepine, phenobarbital, phenytoin.
- Antibiotics: rifapentine.
Other Drug-Food Interactions
Grapefruit juice reduces CYP3A4-mediated drug metabolism.
Grapefruit juice must not be taken with or used for dilution of Rapamune [see DOSAGE
AND ADMINISTRATION, DRUG INTERACTIONS].
Drug-Herb Interactions
St. John's Wort (Hypericum perforatum) induces
CYP3A4 and P-gp. Since sirolimus is a substrate for both cytochrome CYP3A4 and
P-gp, there is the potential that the use of St. John's Wort in patients
receiving Rapamune could result in reduced sirolimus concentrations [see
DRUG INTERACTIONS].
Clinical Studies
Prophylaxis Of Organ Rejection In Renal Transplant
Patients
Rapamune Oral Solution
The safety and efficacy of Rapamune Oral Solution for the
prevention of organ rejection following renal transplantation were assessed in
two randomized, double-blind, multicenter, controlled trials. These studies
compared two dose levels of Rapamune Oral Solution (2 mg and 5 mg, once daily)
with azathioprine (Study 1) or placebo (Study 2) when administered in
combination with cyclosporine and corticosteroids. Study 1 was conducted in the
United States at 38 sites. Seven hundred nineteen (719) patients were enrolled
in this trial and randomized following transplantation; 284 were randomized to
receive Rapamune Oral Solution 2 mg/day; 274 were randomized to receive
Rapamune Oral Solution 5 mg/day, and 161 to receive azathioprine 2-3 mg/kg/day.
Study 2 was conducted in Australia, Canada, Europe, and the United States, at a
total of 34 sites. Five hundred seventy-six (576) patients were enrolled in
this trial and randomized before transplantation; 227 were randomized to
receive Rapamune Oral Solution 2 mg/day; 219 were randomized to receive
Rapamune Oral Solution 5 mg/day, and 130 to receive placebo. In both studies,
the use of antilymphocyte antibody induction therapy was prohibited. In both
studies, the primary efficacy endpoint was the rate of efficacy failure in the
first 6 months after transplantation. Efficacy failure was defined as the first
occurrence of an acute rejection episode (confirmed by biopsy), graft loss, or
death.
The tables below summarize the results of the primary
efficacy analyses from these trials. Rapamune Oral Solution, at doses of 2
mg/day and 5 mg/day, significantly reduced the incidence of efficacy failure
(statistically significant at the < 0.025 level; nominal significance level
adjusted for multiple [2] dose comparisons) at 6 months following
transplantation compared with both azathioprine and placebo.
TABLE 8: INCIDENCE (%) OF EFFICACY FAILURE AT 6 AND 24
MONTHS FOR STUDY 1a,b
Parameter |
Rapamune Oral Solution 2 mg/day
(n = 284) |
Rapamune Oral Solution 5 mg/day
(n = 274) |
Azathioprine 2-3 mg/kg/day
(n = 161) |
Efficacy failure at 6 monthsc |
18.7 |
16.8 |
32.3 |
Components of efficacy failure |
Biopsy-proven |
16.5 |
11.3 |
29.2 |
acute rejection |
|
|
|
Graft loss |
1.1 |
2.9 |
2.5 |
Death |
0.7 |
1.8 |
0 |
Lost to follow-up |
0.4 |
0.7 |
0.6 |
Efficacy failure at 24 months |
32.8 |
25.9 |
36.0 |
Components of efficacy failure |
Biopsy-proven acute rejection |
23.6 |
17.5 |
32.3 |
Graft loss |
3.9 |
4.7 |
3.1 |
Death |
4.2 |
3.3 |
0 |
Lost to follow-up |
1.1 |
0.4 |
0.6 |
a Patients received cyclosporine and
corticosteroids.
b Includes patients who prematurely discontinued treatment.
c Primary endpoint. |
TABLE 9: INCIDENCE (%) OF EFFICACY FAILURE AT 6 AND 36
MONTHS FOR STUDY 2a,b
Parameter |
Rapamune Oral Solution 2 mg/day
(n = 227) |
Rapamune Oral Solution 5 mg/day
(n = 219) |
Placebo
(n = 130) |
Efficacy failure at 6 monthsc |
30.0 |
25.6 |
47.7 |
Components of efficacy failure |
Biopsy-proven acute rejection |
24.7 |
19.2 |
41.5 |
Graft loss |
3.1 |
3.7 |
3.9 |
Death |
2.2 |
2.7 |
2.3 |
Lost to follow-up |
0 |
0 |
0 |
Efficacy failure at 36 months |
44.1 |
41.6 |
54.6 |
Components of efficacy failure |
Biopsy-proven acute rejection |
32.2 |
27.4 |
43.9 |
Graft loss |
6.2 |
7.3 |
4.6 |
Death |
5.7 |
5.9 |
5.4 |
Lost to follow-up |
0 |
0.9 |
0.8 |
a Patients received cyclosporine and
corticosteroids.
b Includes patients who prematurely discontinued treatment.
c Primary endpoint. |
Patient and graft survival at 1 year were co-primary
endpoints. The following table shows graft and patient survival at 1 and 2
years in Study 1, and 1 and 3 years in Study 2. The graft and patient survival
rates were similar in patients treated with Rapamune and comparator-treated
patients.
TABLE 10: GRAFT AND PATIENT SURVIVAL (%) FOR STUDY 1
(12 AND 24 MONTHS) AND STUDY 2 (12 AND 36 MONTHS)a,b
Parameter |
Rapamune Oral Solution 2 mg/day |
Rapamune Oral Solution 5 mg/day |
Azathioprine 2-3 mg/kg/day |
Placebo |
Study 1 |
(n = 284) |
(n = 274) |
(n = 161) |
|
Graft survival |
Month 12 |
94.7 |
92.7 |
93.8 |
|
Month 24 |
85.2 |
89.1 |
90.1 |
|
Patient survival |
Month 12 |
97.2 |
96.0 |
98.1 |
|
Month 24 |
92.6 |
94.9 |
96.3 |
|
Study 2 |
(n = 227) |
(n = 219) |
|
(n = 130) |
Graft survival |
Month 12 |
89.9 |
90.9 |
|
87.7 |
Month 36 |
81.1 |
79.9 |
|
80.8 |
Patient survival |
Month 12 |
96.5 |
95.0 |
|
94.6 |
Month 36 |
90.3 |
89.5 |
|
90.8 |
a Patients received cyclosporine and
corticosteroids.
b Includes patients who prematurely discontinued treatment. |
The reduction in the incidence of first biopsy-confirmed
acute rejection episodes in patients treated with Rapamune compared with the
control groups included a reduction in all grades of rejection.
In Study 1, which was prospectively stratified by race
within center, efficacy failure was similar for Rapamune Oral Solution 2 mg/day
and lower for Rapamune Oral Solution 5 mg/day compared with azathioprine in
Black patients. In Study 2, which was not prospectively stratified by race,
efficacy failure was similar for both Rapamune Oral Solution doses compared
with placebo in Black patients. The decision to use the higher dose of Rapamune
Oral Solution in Black patients must be weighed against the increased risk of
dose-dependent adverse events that were observed with the Rapamune Oral
Solution 5-mg dose [see ADVERSE REACTIONS].
TABLE 11: PERCENTAGE OF EFFICACY FAILURE BY RACE AT 6
MONTHSa,b
Parameter |
Rapamune Oral Solution 2 mg/day |
Rapamune Oral Solution 5 mg/day |
Azathioprine 2-3 mg/kg/day |
Placebo |
Study 1 |
Black
(n = 166) |
34.9
(n = 63) |
18.0
(n = 61) |
33.3
(n = 42) |
|
Non-Black
(n = 553) |
14.0
(n = 221) |
16.4
(n = 213) |
31.9
(n = 119) |
|
Study 2 |
Black
(n = 66) |
30.8
(n = 26) |
33.7
(n = 27) |
|
38.5
(n = 13) |
Non-Black
(n = 510) |
29.9
(n = 201) |
24.5
(n = 192) |
|
48.7
(n = 117) |
a Patients received cyclosporine and
corticosteroids.
b Includes patients who prematurely discontinued treatment. |
Mean glomerular filtration rates (GFR) post-transplant
were calculated by using the Nankivell equation at 12 and 24 months for Study
1, and 12 and 36 months for Study 2. Mean GFR was lower in patients treated
with cyclosporine and Rapamune Oral Solution compared with those treated with
cyclosporine and the respective azathioprine or placebo control.
TABLE 12: OVERALL CALCULATED GLOMERULAR FILTRATION
RATES (Mean ± SEM, cc/min) BY NANKIVELL EQUATION POST-TRANSPLANTa,b
Parameter |
Rapamune Oral Solution 2 mg/day |
Rapamune Oral Solution 5 mg/day |
Azathioprine 2-3 mg/kg/day |
Placebo |
Study 1 |
Month 12 |
57.4 ± 1.3 |
54.6 ± 1.3 |
64.1 ± 1.6) |
|
(n = 269) |
(n = 248) |
(n = 149) |
|
Month 24 |
58.4 ± 1.5 |
52.6 ± 1.5 |
62.4 ± 1.9 |
|
(n = 221) |
(n = 222) |
(n = 132) |
|
Study 2 |
Month 12 |
52.4 ± 1.5 |
51.5 ± 1.5 |
|
58.0 ± 2.1 |
(n = 211) |
(n = 199) |
|
(n = 117) |
Month 36 |
48.1 ± 1.8 |
46.1 ± 2.0 |
|
53.4 ± 2.7 |
(n = 183) |
(n = 177) |
|
(n = 102) |
a Includes patients who prematurely
discontinued treatment.
b Patients who had a graft loss were included in the analysis with
GFR set to 0.0. |
Within each treatment group in Studies 1 and 2, mean GFR
at one-year post-transplant was lower in patients who experienced at least one
episode of biopsy-proven acute rejection, compared with those who did not.
Renal function should be monitored, and appropriate
adjustment of the immunosuppressive regimen should be considered in patients
with elevated or increasing serum creatinine levels [see WARNINGS AND
PRECAUTIONS].
Rapamune Tablets
The safety and efficacy of Rapamune Oral Solution and
Rapamune Tablets for the prevention of organ rejection following renal
transplantation were demonstrated to be clinically equivalent in a randomized,
multicenter, controlled trial [see CLINICAL PHARMACOLOGY].
Cyclosporine Withdrawal Study In Renal Transplant
Patients
The safety and efficacy of Rapamune as a maintenance
regimen were assessed following cyclosporine withdrawal at 3 to 4 months after
renal transplantation. Study 3 was a randomized, multicenter, controlled trial
conducted at 57 centers in Australia, Canada, and Europe. Five hundred
twenty-five (525) patients were enrolled. All patients in this study received
the tablet formulation. This study compared patients who were administered
Rapamune, cyclosporine, and corticosteroids continuously with patients who
received this same standardized therapy for the first 3 months after
transplantation (pre-randomization period) followed by the withdrawal of
cyclosporine. During cyclosporine withdrawal, the Rapamune dosages were adjusted
to achieve targeted sirolimus whole blood trough concentration ranges (16 to 24
ng/mL until month 12, then 12 to 20 ng/mL thereafter, expressed as
chromatographic assay values). At 3 months, 430 patients were equally
randomized to either continue Rapamune with cyclosporine therapy or to receive
Rapamune as a maintenance regimen following cyclosporine withdrawal.
Eligibility for randomization included no Banff Grade 3
acute rejection or vascular rejection episode in the 4 weeks before random
assignment, serum creatinine ≤ 4.5 mg/dL, and adequate renal function to
support cyclosporine withdrawal (in the opinion of the investigator). The
primary efficacy endpoint was graft survival at 12 months after
transplantation. Secondary efficacy endpoints were the rate of biopsy-confirmed
acute rejection, patient survival, incidence of efficacy failure (defined as
the first occurrence of either biopsy-proven acute rejection, graft loss, or
death), and treatment failure (defined as the first occurrence of either
discontinuation, acute rejection, graft loss, or death).
The following table summarizes the resulting graft and
patient survival at 12, 24, and 36 months for this trial. At 12, 24, and 36
months, graft and patient survival were similar for both groups.
TABLE 13: GRAFT AND PATIENT SURVIVAL (%): STUDY 3a
Parameter |
Rapamune with Cyclosporine Therapy
(n = 215) |
Rapamune Following Cyclosporine Withdrawal
(n = 215) |
Graft Survival |
Month 12b |
95.3c |
97.2 |
Month 24 |
91.6 |
94.0 |
Month 36d |
87.0 |
91.6 |
Patient Survival |
Month 12 |
97.2 |
98.1 |
Month 24 |
94.4 |
95.8 |
Month 36d |
91.6 |
94.0 |
a Includes patients who prematurely
discontinued treatment.
b Primary efficacy endpoint.
c Survival including loss to follow-up as an event.
d Initial planned duration of the study. |
The following table summarizes the results of first
biopsy-proven acute rejection at 12 and 36 months. There was a significant
difference in first biopsy-proven rejection rates between the two groups after
randomization and through 12 months. Most of the post-randomization acute rejections
occurred in the first 3 months following randomization.
TABLE 14: INCIDENCE OF FIRST BIOPSY-PROVEN ACUTE
REJECTION (%) BY TREATMENT GROUP AT 36 MONTHS: STUDY 3a,b
Period |
Rapamune with Cyclosporine Therapy
(n = 215) |
Rapamune Following Cyclosporine Withdrawal
(n = 215) |
Pre-randomizationc |
9.3 |
10.2 |
Post-randomization through 12 monthsc |
4.2 |
9.8 |
Post-randomization from 12 to 36 months |
1.4 |
0.5 |
Post-randomization through 36 months |
5.6 |
10.2 |
Total at 36 months |
14.9 |
20.5 |
a Includes patients who prematurely
discontinued treatment.
b All patients received corticosteroids.
c Randomization occurred at 3 months ± 2 weeks. |
Patients receiving renal allografts with ≥4 HLA
mismatches experienced significantly higher rates of acute rejection following
randomization to the cyclosporine withdrawal group, compared with patients who
continued cyclosporine (15.3% versus 3.0%). Patients receiving renal allografts
with ≤3 HLA mismatches demonstrated similar rates of acute rejection
between treatment groups (6.8% versus 7.7%) following randomization.
The following table summarizes the mean calculated GFR in
Study 3 (cyclosporine withdrawal study).
TABLE 15: CALCULATED GLOMERULAR FILTRATION RATES
(mL/min) BY NANKIVELL EQUATION AT 12, 24, AND 36 MONTHS POST-TRANSPLANT: STUDY
3a,b,c
Parameter |
Cyclosporine Therapy |
Cyclosporine Withdrawal |
Month 12 |
Mean ± SEM |
53.2 ± 1.5 |
59.3 ± 1.5 |
|
(n = 208) |
(n = 203) |
Month 24 |
Mean ± SEM |
48.4 ± 1.7 |
58.4 ± 1.6 |
|
(n = 203) |
(n = 201) |
Month 36 |
Mean ± SEM |
47.0 ± 1.8 |
58.5 ± 1.9 |
|
(n = 196) |
(n = 199) |
a Includes patients who prematurely
discontinued treatment.
b Patients who had a graft loss were included in the analysis and
had their GFR set to 0.0.
c All patients received corticosteroids. |
The mean GFR at 12, 24, and 36 months, calculated by the
Nankivell equation, was significantly higher for patients receiving Rapamune as
a maintenance regimen following cyclosporine withdrawal than for those in the
Rapamune with cyclosporine therapy group. Patients who had an acute rejection
prior to randomization had a significantly higher GFR following cyclosporine
withdrawal compared to those in the Rapamune with cyclosporine group. There was
no significant difference in GFR between groups for patients who experienced
acute rejection post-randomization.
Although the initial protocol was designed for 36 months,
there was a subsequent amendment to extend this study. The results for the
cyclosporine withdrawal group at months 48 and 60 were consistent with the
results at month 36. Fifty-two percent (112/215) of the patients in the
Rapamune with cyclosporine withdrawal group remained on therapy to month 60 and
showed sustained GFR.
High-Immunologic Risk Renal Transplant Patients
Rapamune was studied in a one-year, clinical trial in
high risk patients (Study 4) who were defined as Black transplant recipients
and/or repeat renal transplant recipients who lost a previous allograft for
immunologic reasons and/or patients with high panel-reactive antibodies (PRA;
peak PRA level > 80%). Patients received concentration-controlled sirolimus
and cyclosporine (MODIFIED), and corticosteroids per local practice. The
Rapamune dose was adjusted to achieve target whole blood trough sirolimus
concentrations of 10-15 ng/mL (chromatographic method) throughout the 12-month
study period. The cyclosporine dose was adjusted to achieve target whole blood
trough concentrations of 200-300 ng/mL through week 2, 150-200 ng/mL from week
2 to week 26, and 100-150 ng/mL from week 26 to week 52 [see CLINICAL
PHARMACOLOGY] for the observed trough concentrations ranges. Antibody
induction was allowed per protocol as prospectively defined at each transplant
center, and was used in 88.4% of patients. The study was conducted at 35
centers in the United States. A total of 224 patients received a transplant and
at least one dose of sirolimus and cyclosporine and was comprised of 77.2%
Black patients, 24.1% repeat renal transplant recipients, and 13.5% patients
with high PRA. Efficacy was assessed with the following endpoints, measured at
12 months: efficacy failure (defined as the first occurrence of
biopsy-confirmed acute rejection, graft loss, or death), first occurrence of
graft loss or death, and renal function as measured by the calculated GFR using
the Nankivell formula. The table below summarizes the result of these
endpoints.
TABLE 16: EFFICACY FAILURE, GRAFT LOSS OR DEATH AND
CALCULATED GLOMERULAR FUNCTION RATES (mL/min) BY NANKIVELL EQUATION AT 12
MONTHS POST-TRANSPLANT: STUDY 4
Parameter |
Rapamune with Cyclosporine, Corticosteroids
(n = 224) |
Efficacy Failure (%) |
23.2 |
Graft Loss or Death (%) |
9.8 |
Renal Function (mean ± SEM)a,b |
52.6 ± 1.6 |
(n = 222) |
a Calculated glomerular filtration rate by
Nankivell equation.
b Patients who had graft loss were included in this analysis with
GFR set to 0. |
Patient survival at 12 months was 94.6%. The incidence of
biopsy-confirmed acute rejection was 17.4% and the majority of the episodes of
acute rejection were mild in severity.
Conversion From Calcineurin Inhibitors To Rapamune In Maintenance
Renal Transplant Patients
Conversion from calcineurin inhibitors (CNI) to Rapamune
was assessed in maintenance renal transplant patients 6 months to 10 years
post-transplant (Study 5). This study was a randomized, multicenter, controlled
trial conducted at 111 centers globally, including US and Europe, and was
intended to show that renal function was improved by conversion from CNI to
Rapamune. Eight hundred thirty (830) patients were enrolled and stratified by
baseline calculated glomerular filtration rate (GFR, 20-40 mL/min versus greater
than 40 mL/min). In this trial there was no benefit associated with conversion
with regard to improvement in renal function and a greater incidence of
proteinuria in the Rapamune conversion arm. In addition, enrollment of patients
with baseline calculated GFR less than 40 mL/min was discontinued due to a
higher rate of serious adverse events, including pneumonia, acute rejection,
graft loss and death [see ADVERSE REACTIONS].
This study compared renal transplant patients (6-120
months after transplantation) who were converted from calcineurin inhibitors to
Rapamune, with patients who continued to receive calcineurin inhibitors.
Concomitant immunosuppressive medications included mycophenolate mofetil (MMF),
azathioprine (AZA), and corticosteroids. Rapamune was initiated with a single
loading dose of 12-20 mg, after which dosing was adjusted to achieve a target
sirolimus whole blood trough concentration of 8-20 ng/mL (chromatographic
method). The efficacy endpoint was calculated GFR at 12 months post-randomization.
Additional endpoints included biopsy-confirmed acute rejection, graft loss, and
death. Findings in the patient stratum with baseline calculated GFR greater
than 40 mL/min (Rapamune conversion, n = 497; CNI continuation, n = 246) are
summarized below. There was no clinically or statistically significant
improvement in Nankivell GFR compared to baseline.
TABLE 17: RENAL FUNCTION IN STABLE RENAL TRANSPLANT
PATIENTS IN PATIENTS WITH BASELINE GFR >40 mL/min THE RAPAMUNE CONVERSION
STUDY (STUDY 5)
Parameter |
Rapamune conversion
N = 496 |
CNI continuation
N = 245 |
Difference (95% CI) |
GFR mL/min (Nankivell) at 1 year |
59.0 |
57.7 |
1.3 (-1.1, 3.7) |
GFR mL/min (Nankivell) at 2 year |
53.7 |
52.1 |
1.6 (-1.4, 4.6) |
The rates of acute rejection, graft loss, and death were
similar at 1 and 2 years. Treatment-emergent adverse events occurred more
frequently during the first 6 months after Rapamune conversion. The rates of
pneumonia were significantly higher for the sirolimus conversion group.
While the mean and median values for urinary protein to
creatinine ratio were similar between treatment groups at baseline,
significantly higher mean and median levels of urinary protein excretion were
seen in the Rapamune conversion arm at 1 year and at 2 years, as shown in the
table below [see WARNINGS AND PRECAUTIONS]. In addition, when compared
to patients who continued to receive calcineurin inhibitors, a higher
percentage of patients had urinary protein to creatinine ratios >1 at 1 and
2 years after sirolimus conversion. This difference was seen in both patients
who had a urinary protein to creatinine ratio ≤1 and those who had a
protein to creatinine ratio >1 at baseline. More patients in the sirolimus
conversion group developed nephrotic range proteinuria, as defined by a urinary
protein to creatinine ratio >3.5 (46/482 [9.5%] versus 9/239 [3.8%]), even
when the patients with baseline nephrotic range proteinuria were excluded. The
rate of nephrotic range proteinuria was significantly higher in the sirolimus
conversion group compared to the calcineurin inhibitor continuation group with
baseline urinary protein to creatinine ratio >1 (13/29 versus 1/14),
excluding patients with baseline nephrotic range proteinuria.
TABLE 18: MEAN AND MEDIAN VALUES FOR URINARY PROTEIN
TO CREATININE RATIO (mg/mg) BETWEEN TREATMENT GROUPS AT BASELINE, 1 AND 2 YEARS
IN THE STRATUM WITH BASELINE CALCULATED GFR >40 mL/min
Study period |
Sirolimus Conversion |
CNI Continuation |
N |
Mean ± SD |
Median |
N |
Mean ± SD |
Median |
p-value |
Baseline |
410 |
0.35 ± 0.76 |
0.13 |
207 |
0.28 ± 0.61 |
0.11 |
0.381 |
1 year |
423 |
0.88 ± 1.61 |
0.31 |
203 |
0.37 ± 0.88 |
0.14 |
<0.001 |
2 years |
373 |
0.86 ± 1.48 |
0.32 |
190 |
0.47 ± 0.98 |
0.13 |
<0.001 |
The above information should be taken into account when
considering conversion from calcineurin inhibitors to Rapamune in stable renal
transplant patients due to the lack of evidence showing that renal function
improves following conversion, and the finding of a greater increment in
urinary protein excretion, and an increased incidence of treatment-emergent
nephrotic range proteinuria following conversion to Rapamune. This was
particularly true among patients with existing abnormal urinary protein
excretion prior to conversion.
In an open-label, randomized, comparative, multicenter
study where kidney transplant patients were either converted from tacrolimus to
sirolimus 3 to 5 months post-transplant (sirolimus group) or remained on
tacrolimus, there was no significant difference in renal function at 2 years
post-transplant. Overall, 44/131 (33.6%) discontinued treatment in the
sirolimus group versus 12/123 (9.8%) in the tacrolimus group. More patients
reported adverse events 130/131 (99.2%) versus 112/123 (91.1%) and more
patients reported discontinuations from the treatment due to adverse events
28/131 (21.4%) versus 4/123 (3.3%) in the sirolimus group compared to the
tacrolimus group.
The incidence of biopsy-confirmed acute rejection was
higher for patients in the sirolimus group 11/131 (8.4%) compared to the
tacrolimus group 2/123 (1.6%) through 2 years post-transplant. The rate of
new-onset diabetes mellitus post-randomization, defined as 30 days or longer of
continuous or at least 25 days non-stop (without gap) use of any diabetic
treatment after randomization, a fasting glucose ≥126 mg/dL or a
non-fasting glucose ≥200 mg/dL, was higher in the sirolimus group 15/82
(18.3%) compared to the tacrolimus group 4/72 (5.6%). A greater incidence of
proteinuria, was seen in the sirolimus group 19/131 (14.5%) versus 2/123 (1.6%)
in the tacrolimus group.
Conversion From A CNI-based Regimen To A Sirolimus-Based Regimen
In Liver Transplant Patients
Conversion from a CNI-based regimen to a Rapamune-based
regimen was assessed in stable liver transplant patients 6-144 months
post-transplant. The clinical study was a 2:1 randomized, multi-center,
controlled trial conducted at 82 centers globally, including the US and Europe,
and was intended to show that renal function was improved by conversion from a
CNI to Rapamune without adversely impacting efficacy or safety. A total of 607
patients were enrolled.
The study failed to demonstrate superiority of conversion
to a Rapamune-based regimen compared to continuation of a CNI-based regimen in
baseline-adjusted GFR, as estimated by Cockcroft-Gault, at 12 months (62 mL/min
in the Rapamune conversion group and 63 mL/min in the CNI continuation group).
The study also failed to demonstrate non-inferiority, with respect to the
composite endpoint consisting of graft loss and death (including patients with
missing survival data) in the Rapamune conversion group compared to the CNI
continuation group (6.6% versus 5.6%). The number of deaths in the Rapamune
conversion group (15/393, 3.8%) was higher than in the CNI continuation group
(3/214, 1.4%), although the difference was not statistically significant. The
rates of premature study discontinuation (primarily due to adverse events or
lack of efficacy), adverse events overall (infections, specifically), and
biopsy-proven acute liver graft rejection at 12 months were all significantly
greater in the Rapamune conversion group compared to the CNI continuation
group.
Pediatric Renal Transplant Patients
Rapamune was evaluated in a 36-month, open-label,
randomized, controlled clinical trial at 14 North American centers in pediatric
(aged 3 to < 18 years) renal transplant patients considered to be at
high-immunologic risk for developing chronic allograft nephropathy, defined as
a history of one or more acute allograft rejection episodes and/or the presence
of chronic allograft nephropathy on a renal biopsy. Seventy-eight (78) subjects
were randomized in a 2:1 ratio to Rapamune (sirolimus target concentrations of
5 to 15 ng/mL, by chromatographic assay, n = 53) in combination with a
calcineurin inhibitor and corticosteroids or to continue
calcineurin-inhibitor-based immunosuppressive therapy (n = 25). The primary
endpoint of the study was efficacy failure as defined by the first occurrence
of biopsy-confirmed acute rejection, graft loss, or death, and the trial was designed
to show superiority of Rapamune added to a calcineurin-inhibitor-based
immunosuppressive regimen compared to a calcineurin-inhibitor-based regimen.
The cumulative incidence of efficacy failure up to 36 months was 45.3% in the
Rapamune group compared to 44.0% in the control group, and did not demonstrate
superiority. There was one death in each group. The use of Rapamune in
combination with calcineurin inhibitors and corticosteroids was associated with
an increased risk of deterioration of renal function, serum lipid abnormalities
(including, but not limited to, increased serum triglycerides and cholesterol),
and urinary tract infections [see WARNINGS AND PRECAUTIONS]. This study
does not support the addition of Rapamune to calcineurin-inhibitor-based
immunosuppressive therapy in this subpopulation of pediatric renal transplant
patients.
Lymphangioleiomyomatosis Patients
The safety and efficacy of Rapamune for treatment of
lymphangioleiomyomatosis (LAM) were assessed in a randomized, double-blind,
multicenter, controlled trial. This study compared Rapamune (dose-adjusted to
maintain blood trough concentrations between 5-15 ng/mL) with placebo for a
12-month treatment period, followed by a 12-month observation period.
Eighty-nine (89) patients were enrolled; 43 patients were randomized to receive
placebo and 46 patients to receive Rapamune. The primary endpoint was the
difference between the groups in the rate of change (slope) per month in forced
expiratory volume in 1 second (FEV1). During the treatment period, the FEV1
slope was -12±2 mL per month in the placebo group and 1±2 mL per month in the
Rapamune group (treatment difference = 13 mL (95% CI: 7, 18). The absolute
between-group difference in the mean change in FEV1 during the 12-month treatment
period was 153 mL, or approximately 11% of the mean FEV1 at enrollment. Similar
improvements were seen for forced vital capacity (FVC). After discontinuation
of Rapamune, the decline in lung function resumed in the Rapamune group and
paralleled that in the placebo group (see Figure 1).
FIGURE 1: CHANGE IN FORCED EXPIRATORY VOLUME IN 1
SECOND (FEV1) DURING THE TREATMENT AND OBSERVATION PHASES OF THE STUDY IN LAM
PATIENTS
The rate of change over 12 months of vascular endothelial
growth factor-D (VEGF-D), a lymphangiogenic growth factor which has been shown
to be elevated in patients with LAM, was significantly different in the
Rapamune-treated group (-88.0 ± 16.6 pg/mL/month) compared to placebo (-2.42 ±
17.2 pg/mL/month) with a treatment difference of -86 pg/mL/month (95% CI: -133,
-39). The absolute between-group difference in the mean change in VEGF-D during
the 12-month treatment period was -1017.2, or approximately 50% of the mean
VEGF-D at enrollment.