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Keywords:

  • Alefacept;
  • tacrolimus;
  • kidney transplantation;
  • mycophenolate;
  • randomized trial

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

Memory T cells play a central role in mediating allograft rejection and are a rational target for immunosuppressive therapy. Alefacept is a recombinant LFA3/IgG1 fusion protein that reduces the number of memory T cells in both psoriatic lesions and the peripheral circulation of psoriasis patients. This study evaluated the efficacy and safety of alefacept compared with placebo when combined with tacrolimus, mycophenolate mofetil and corticosteroids in de novo renal transplant recipients. Between December 2007 and March 2009 patients were randomized in a double-blind fashion to receive alefacept (n = 105) or placebo (n = 107) for 3 months and were then followed for a further 3 months. The primary efficacy endpoint was the incidence of biopsy-confirmed acute T cell mediated rejection (Banff grade ≥1) through Month 6. Memory T cell counts were significantly reduced in the alefacept group from Week 3 to study end compared with placebo. However, there was no significant difference between the alefacept and placebo groups for the primary efficacy endpoint (alefacept, 11.0% vs. placebo, 7.0%, p = 0.3). Patient and graft survival as well as renal function was similar between treatment groups. Safety and tolerability were generally similar between the treatment arms. Malignancy was higher in the alefacept treatment arm.


Abbreviations
AE

adverse event

AMR

antibody-mediated rejection

AR

acute rejection

BCAR

biopsy-confirmed acute T cell mediated rejection

CI

confidence interval

CNI

calcineurin inhibitor

CMV

cytomegalovirus

DGF

delayed graft function

FAS

full-analysis set

Fc

crystallizable fragment

i.v.

intravenous

MDRD

modification of diet in renal disease

MMF

mycophenolate mofetil

NODAT

new-onset diabetes after transplantation

PK

pharmacokinetics

PKAS

pharmacokinetics analysis set

PRA

panel reactive antibody

SAE

serious adverse event

SAF

safety-analysis set

Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

Memory T cells have a critical, protective function in adaptive immunity that becomes disadvantageous in the context of transplantation. Together with naïve T cells, memory T cells are central to the mediation of allograft rejection, but have reduced activation requirements that result in a more rapid and vigorous alloresponse than that triggered by naïve T cells [1-3]. In humans, alloreactive T cells reside similarly in the naïve and memory T cellT cell pools. Memory T cells are less sensitive to current immunosuppressive agents than naïve T cells. Although memory T cells are sensitive to calcineurin inhibitors (CNIs), current agents fail to completely control the immune response. Given that approximately half of an adult human's T cells are memory T cells and that the widespread presence of memory T cells in peripheral tissues allows rapid exposure to posttransplantation alloantigens [2, 3], it seems relevant that memory T cells be suppressed following transplantation. Even unsensitized transplant recipients have varying levels of alloreactive memory T cells, resulting either from heterologous immunity (i.e. T cells responsive to one antigen also reacting to unrelated antigens) or homeostatic proliferation.

Alefacept is a dimeric human fusion protein that consists of the CD2-binding portion of the leukocyte function antigen-3 linked to the crystallizable fragment (Fc) region of IgG1 [4]. Alefacept is well established as a safe and effective monotherapy for psoriasis, exerting its therapeutic effect via dose-dependent depletion of memory T cells [4, 5]. Alefacept acts by binding to the CD2 receptor, which is upregulated on effector memory T cells (CD4+CD45RO+ and CD8+CD45RO+), thereby inhibiting effector memory T cell function and evoking apoptosis; whereas central memory T cells are less affected and naïve T cells remain mostly spared [2, 6, 7]. Based on its pharmacologic activity and success in treating psoriasis, the development of alefacept as immunosuppressive therapy following transplantation has been investigated.

The present study was performed in order to evaluate the efficacy and safety of alefacept compared with placebo when administered in combination with a standard-of-care immunosuppressive regimen (tacrolimus, mycophenolate mofetil [MMF] and corticosteroids) in de novo kidney transplant recipients.

Materials and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

Patients

Adult patients (aged 18–65 years) who were suitable candidates for primary renal transplantation or re-transplantation from a nonHLA identical living donor or a deceased donor aged between 5 and 59 years with compatible ABO blood type were enrolled in the study. Key exclusion criteria were a panel reactive antibody (PRA) level of >20% in the previous 6 months and/or previous graft survival of <1 year due to immunological reasons; previous nonrenal transplant; kidney transplant from an expanded criteria donor or from a cardiac death donor; cold ischemia time of ≥30 h; significant liver disease; history of malignancy; or uncontrolled infection.

The study (EudraCT number 2007-002092-14; ClinicalTrials.gov NCT00617604) was conducted in accordance with the Declaration of Helsinki, Good Clinical Practice and the International Conference on Harmonisation guidelines. The protocol was reviewed by the National and Institutional Independent Ethics Committees as well as the National Health Authorities of all participating European countries. Patients gave written informed consent before study enrollment.

Study design and procedures

This multicenter, 1:1 randomized, double-blind, placebo-controlled, parallel-group, phase II study was conducted in 27 centers in 12 European countries (December 2007–September 2009). After screening, eligible patients underwent transplantation and entered a 12-week double-blind treatment period, in which study drug was added to the EU standard-of-care immunosuppressive regimen, followed by a further 12-week period of maintenance standard-of-care immunosuppression. Treatment allocation was stratified by center and performed in a blinded manner according to a randomization schedule provided by IFE Europe GmbH. Each center was allocated a unique sequence of randomization numbers in a block size of four. Only the authorized unblinded person(s), for example, the pharmacist(s) or designee(s) at the study center, who were not directly involved in the subject management, were aware of the treatment arm into which the subject was randomized. Study drug allocation was concealed in a sealed envelope for use by the investigator in the case of emergency treatment decisions.

Primary immunosuppression regimen

Patients received the first dose of alefacept on the day of transplantation (Day 0), together with tacrolimus, MMF and corticosteroids. Alefacept 7.5 mg was administered intraoperatively, prior to reperfusion as an intravenous (i.v.) bolus. A second 7.5 mg i.v. bolus of alefacept was administered on Day 3, with subsequent doses of 15 mg alefacept (0.5 mL reconstituted solution) given weekly as subcutaneous injections for 12 weeks. The same dosing schedule and volume of solution was applied to the placebo arm, in which a saline solution was administered.

The rationale for the alefacept dosing schedule was based on the currently approved dosing schedule for the treatment of psoriasis (7.5 mg i.v. or 15 mg intramuscularly) for 12 weeks. Given the relative robustness of the host allograft response compared with the immune response in psoriasis, it was considered unlikely that a lower dose, which was not effective in psoriasis, would be effective in organ transplantation. Furthermore, phase I studies showed that higher doses of alefacept did not result in a greater reduction of CD2+CD45RO+ cells peripherally [Astellas data on file (Company Report C95-701, November 2000)].

Adjunct immunosuppression

The initial tacrolimus treatment regimen was 0.2 mg/kg/day administered orally in two equal doses (i.e. 0.1 mg/kg twice daily), starting within 24 h after completion of surgery. For recipients of a living donor organ, predosing with tacrolimus was permitted providing that it was within 72 h prior to reperfusion and the dosage did not exceed 0.2 mg/kg/day. Subsequent oral tacrolimus doses were adjusted according to clinical evidence of efficacy and tolerability, and to maintain recommended whole blood trough levels of 10–20 ng/mL (Days 0–28), 7–16 ng/mL (Days 29–90) and 5–15 ng/mL (Day 91 onwards).

The MMF treatment regimen was 750 mg twice daily administered orally. Dosing could be initiated preoperatively and any adjustments were based on clinical symptoms and laboratory findings. Methylprednisolone (or equivalent) was administered as i.v. bolus doses of 500–1000 mg on Day 0 and 125–250 mg on Day 1. Thereafter, oral prednisolone (or equivalent) was given at 20–30 mg/day (Days 2–14), 10–20 mg/day (Days 15–28), 10–15 mg/day (Days 29–60) and 5–10 mg/day (Days 61 onward).

Treatment of rejection

First-line acute rejection (AR) therapy was the administration of corticosteroids according to local practice. Corticosteroid-resistant AR was treated with polyclonal anti-lymphocyte antibodies. If the biopsy indicated a severe vascular rejection (Banff IIB or III), first-line therapy with antibodies was permitted.

Viral, bacterial and fungal prophylaxis

Prophylactic antiviral treatment was required for cytomegalovirus (CMV) when a CMV-positive donor graft was transplanted into a CMV-negative patient. Furthermore, prophylaxis for bacterial and fungal infections was administered to all enrolled patients.

Endpoints

The primary efficacy endpoint was the incidence of biopsy-confirmed acute T cell mediated rejection (BCAR; Banff grade ≥1) through Month 6. Renal biopsy was indicated in all cases where clinical and/or laboratory signs indicated the occurrence of an AR, prior to starting rejection therapy. Biopsies were evaluated by the local histopathologist and graded according to the Banff 97/05 updated criteria [8].

Secondary efficacy endpoints were also evaluated through Month 6. These included incidences of antibody-mediated rejection (AMR) or combined acute cellular rejection and AMR (biopsy confirmed); AR diagnosed by signs and symptoms, clinically treated AR (defined as receiving immuosuppressive medications for the treatment of suspected AR or BCAR) and corticosteroid-resistant AR; patient survival; graft survival and graft loss (graft loss was defined as re-transplantation, graft nephrectomy, death or dialysis ongoing at study end or discontinuation); maximum Banff grade of BCAR; incidence of antilymphocyte antibody therapy for treatment of rejection; renal function (serum creatinine concentration, GFR calculated using the modification of diet in renal disease (MDRD) formula); efficacy failure (defined as death, graft loss, BCAR or lost to follow-up) and delayed graft function (DGF; defined as requirement for dialysis within the first week posttransplantation). Lymphocyte subset counts were also evaluated throughout the study. Safety and tolerability were evaluated throughout the study by recording adverse events (AEs), laboratory parameters, infections, vital signs and the incidence of new-onset diabetes mellitus posttransplantation (NODAT; defined as a composite of the first occurrence of fasting serum glucose ≥126 mg/dL [7.0 mmol/L] on two occasions beginning with Month 4, hypoglycemic agent use >30 days at any time or insulin use >30 days at any time).

Statistical analyses

Efficacy endpoints were analyzed for the full-analysis set (FAS), that is, all randomized and transplanted patients who received at least one dose of study drug. Safety and tolerability were evaluated in all randomized patients who received at least one dose of study drug (safety-analysis set [SAF]). Pharmacokinetic (PK) analysis was performed on the pharmacokinetics analysis set (PKAS), that is patients from the SAF population who were enrolled in the PK sub-study and for whom sufficient plasma concentration data are available to facilitate derivation of at least one PK parameter. Patients were analyzed according to their randomized treatment assignment.

The sample size for this proof of concept study was based on practical considerations. However a prior calculation indicated an estimated 100 patients per treatment arm would be required to achieve a power of 63% for a significance level of α = 0.10 (two-sided, normal approximation superiority test), assuming BCAR rates of 10% and 20% for the investigational arm and the control arm, respectively (power calculated using nQuery Advisor version 4.0). The sample size is consistent with other Phase 2 studies of immunosuppressive agents in renal transplantation.

The primary endpoint, incidence of T cell mediated BCAR through Month 6, was analyzed using Kaplan–Meier methods and the differences between the treatment arms were evaluated using the Wilcoxon–Gehan test at a two-sided 0.10 significance level. The Wilcoxon–Gehan test was selected a priori as the proportional hazards assumption was not expected to be met and the majority of failure times for BCAP events were expected to occur within the first 2–3 months. In addition, two-sided 90% confidence intervals (CI) were calculated for Kaplan–Meier estimates of the BCAR rate through Month 6 for both treatment arms and their difference. Patients without a BCAR episode who were lost to follow-up (or patients with missing outcomes, for example due to death or graft loss) were censored at their last follow-up visit in this analysis.

The methods used for the primary efficacy endpoint analysis were also used to analyze the following secondary efficacy endpoints: incidences of AR, clinically treated AR and corticosteroid-resistant AR; patient and graft survival; efficacy failure and incidence of antilymphocyte antibody therapy for treatment of rejection. In addition, DGF, efficacy failure and incidence of antilymphocyte antibody therapy were analyzed using the Chi-square test or Fisher's exact test in case there were insufficient expected cell counts. The analysis of the maximum grade of BCAR (Banff criteria IA–III) was performed using the Cochran–Mantel–Haenszel test. Renal function outcomes and T-lymphocyte counts were compared using analysis of variance methods at each visit.

Safety and tolerability data were summarized using descriptive statistics. Adverse events (AEs) were coded using the Medical Dictionary for Regulatory Activities version 11.0.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

Patients

Between December 2007 and March 2009, 218 patients were enrolled and randomized to treatment with either alefacept or placebo (Figure 1). Of these, 212 patients (alefacept, n = 105; placebo, n = 107) received at least one dose of study drug and were included in the SAF. All of these patients also had undergone transplantation and thus comprised the FAS for analyzing efficacy.

image

Figure 1. Patient disposition. 1FAS (all randomized and transplanted patients who received at least one dose of study drug). 2For every patient, only the primary reason for discontinuation was collected. FAS, full analysis set.

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Demographic and baseline disease characteristics were broadly similar across the two treatment groups (Table 1).

Table 1. Demographic and baseline characteristics
CharacteristicAlefacept (n = 105)Placebo (n = 107)
  1. ESRD, end-stage renal disease; PRA, panel reactive antibody; SD, standard deviation.

Age, mean (SD) years44.2 (11.9)46.5 (11.3)
Male, n (%)65 (61.9)74 (69.2)
Reported cause of ESRD, n (%)
Polycystic kidney disease23 (21.9)26 (24.3)
Glomerulonephritis18 (17.1)20 (18.7)
Diabetes12 (11.4)10 (9.3)
Hypertensive nephropathy7 (6.7)11 (10.3)
Immunoglobulin A nephropathy9 (8.6)8 (7.5)
Tubular and interstitial disease9 (8.6)4 (3.7)
Other16 (15.2)15 (14.0)
Unknown11 (10.5)13 (12.1)
Had previous transplant, n (%)9 (8.6)7 (6.5)
PRA ≥20, n (%)0 (0)2 (1.9)
≥3 HLA mismatches, n (%)80 (76.2)76 (71.7)
Deceased donor, n (%)88 (83.8)86 (80.4)
Donor age, mean (SD) years43.4 (11.6)44.2 (11.2)
Cold ischemia time, mean (SD) hours14.0 (6.9)13.5 (7.2)

Immunosuppression

The mean daily dose of alefacept was in accordance with the protocol. Based on the number of alefacept/placebo doses expected, mean treatment adherence was seen in 97.6% and 98.9% of alefacept and placebo subjects respectively. Mean plasma trough concentrations increased immediately following transplant through 84 days and then declined, however, these differences were not statistically significant (Figure 2; PKAS).

image

Figure 2. Mean alefacept plasma trough concentration over time (FAS). The 12-week alefacept dosing period is indicated. Note: The x-axis is categorical. FAS, full analysis set; SD, standard deviation.

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The mean total daily dose of tacrolimus was slightly higher in the alefacept group compared with the placebo group throughout the study (data not shown). However, mean whole blood trough levels of tacrolimus were similar across both treatment groups for the study duration (Figure 3).

image

Figure 3. Mean tacrolimus plasma trough concentration over time (FAS). Target trough levels were the same for both treatment groups. Note: The x-axis is categorical. FAS, full analysis set; SD, standard deviation.

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The use of MMF and corticosteroids was consistent across the placebo and alefacept treatment groups (median daily doses: MMF, 1491 mg vs. 1485 mg; corticosteroids, 14.5 mg vs. 13.8 mg).

Efficacy

Kaplan–Meier estimate of the incidence of T cell mediated BCAR through 6 months, the primary endpoint, was not significantly different between the alefacept- and placebo-treatment groups (11% vs. 7%; p = 0.309; Figure 4). All BCAR episodes occurred within the first 7 weeks after reperfusion and the majority occurred in the first 2 weeks. The majority of BCARs were grade IIA or IIB (8 of 11 with alefacept, 4 of 7 with placebo). In addition, grade I or II AMR occurred in 3.8% of the alefacept group and 2.8% of placebo-treated subjects (p = 0.696). As C4d staining was not performed on all biopsies, a complete evaluation for AMR could not be performed.

image

Figure 4. Primary efficacy endpoint: incidence of T cell mediated BCAR (Kaplan–Meier estimates; FAS). Events occurring between baseline and Month 6 were included. The p-value was obtained from Wilcoxon–Gehan test. BCAR, biopsy confirmed acute T cell mediated rejection; FAS, full analysis set.

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There were no statistically significant differences between the treatment groups in any of the secondary efficacy endpoints, including rejections, antilymphocyte antibody therapy for rejection, patient and graft survival, graft loss, DGF and efficacy failure (Table 2).

Table 2. Summary of key secondary efficacy endpoints (FAS)
Endpoint through Month 6Alefacept (n = 105)Placebo (n = 107)p-Value
  • FAS, full analysis set; CI, confidence interval; AR, acute rejection; AMR, antibody-mediated rejection; BCAR, biopsy-confirmed acute T cell mediated rejection (Banff grade ≥1) assessed locally; DGF, delayed graft function.

  • 1

    Wilcoxon–Gehan test.

  • 2

    Chi-square test.

Rejections, % (90% CI)
AR diagnosed by signs and symptoms21.9 (16–29)26.6 (20–35)0.3231
AMR3.8 (0.7–6.9)2.8 (0.2–5.5)0.6961
Corticosteroid-resistant AR5.7 (2–10)7.5 (3–12)0.6201
Clinically-treated AR15.4 (10–21)24.8 (18–32)0.1041
T cell mediated AR or AMR12.4 (7.1–17.7)9.3 (4.7–14.0)0.4772
Borderline T cell mediated AR, T cell mediated BCAR or AMR16.4 (10.4–22.4)20.0 (13.6–26.5)0.4871
Maximum Banff Grade of BCAR, n (%)
IA2 (1.9)3 (2.8)
IB1 (1.0)0 (0)
IIA5 (4.8)2 (1.9)
IIB3 (2.9)2 (1.9)
III0 (0)0 (0)
Antilymphocyte antibody therapy for rejection7 (6.7)5 (4.7)0.5302
Patient survival, % (90% CI)99 (97–100)97 (94–100)0.3501
Graft survival, % (90% CI)95 (92–99)91 (86–95)0.2331
Graft loss, n (%)5 (4.8)10 (9.3)0.1932
Efficacy failure, n (%)24 (22.9)18 (16.8)0.2702
DGF, n (%)8 (7.6)13 (12.1)0.2702

T-lymphocyte subset counts

There were no significant differences in the mean counts for CD4+CD45RA+ cells (i.e. CD4+ naïve T cells) between the treatment groups (Figure 5). From Week 1 to Month 6, mean counts ranged from 332 to 492 cells/µL in the alefacept group and 309–428 cells/µL in the placebo group. Similar results were observed for CD8+CD45RA+ counts, although the count with alefacept was significantly lower compared with that in the placebo group at Week 3 (p = 0.042; Figure 4).

image

Figure 5. Counts of naïve T cells (CD4+CD45RA+ and CD8+CD45RA+) and memory T cells (CD4+CD45RO+ and CD8+CD45RO+) over time (FAS). Patients received study drug until Day 84, with the end of the dosing period indicated by the arrow. p-Values were obtained from an analysis of variance model. FAS, full analysis set.

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At Weeks 1 and 2, mean counts for CD4+CD45RO+ cells (i.e. CD4+ memory T cells) were similar in the alefacept- and placebo-treatment groups (Week 1, 328 cells/µL vs. 333 cells/µL; Week 2, 437 cells/µL vs. 477 cells/µL, respectively; Figure 4). From Week 3 to Month 6, mean counts for CD4+CD45RO+ cells were significantly lower in the alefacept group compared with the placebo group (Week 3 to Month 5, p ≤ 0.001; Month 6, p = 0.057). Similar results were observed for the CD8+CD45RO+ counts (Figure 4).

Renal function

Renal function was similar in both the treatment groups for the duration of the study. Mean levels of serum creatinine and estimated GFR (calculated using the MDRD) improved following transplantation and remained stable from Week 6 onwards, with no statistically significant differences between the treatment groups (Figure 6).

image

Figure 6. Renal function over time (FAS). FAS, full analysis set; MDRD, modification of diet in renal disease.

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Safety and tolerability

AEs, treatment-related AEs, serious AEs (SAEs) and treatment-related SAEs generally occurred with a similar frequency in the two treatment groups (Table 3). The most common AEs (reported in ≥15% of patients) occurred similarly in the alefacept and placebo groups and included anemia, diarrhea, urinary tract infections and hypertension (Table 4). More patients experienced CMV infections (8.6% vs. 5.6%, p = 0.43) or CMV viremia (5.7% vs. 1.9%, p = 0.17) whereas fewer patients experienced BK viral infections (2.9% vs. 7.5%, p = 0.21) in the alefacept group compared with the placebo group, respectively.

Table 3. Summary of AEs (FAS)
AE category, n (%)Alefacept (n = 105)Placebo (n = 107)
  • AE, adverse event; FAS, full analysis set; SAE, serious adverse event.

  • 1

    Defined as possibly or probably related to study drug according to the investigator or where relationship to study drug was not recorded.

Total AEs101 (96.2)102 (95.3)
AEs related to study drug141 (39.0)36 (33.6)
SAEs57 (54.3)62 (57.9)
SAEs related to study drug116 (15.2)19 (17.8)
AEs leading to discontinuation of study drug10 (9.5)7 (6.5)
Table 4. Most common AEs, AEs of special interest, SAEs and cardiac AEs (FAS)
AE category, n (%)Alefacept (n = 105)Placebo (n = 107)p-Value3
  • AE, adverse event; CMV, cytomegalovirus; SAE, serious adverse event; MedDRA, Medical Dictionary for Regulatory Activities. AEs listed by MedDRA term.

  • 1

    Occurring in ≥15% of patients in either treatment group.

  • 2

    Occurring in ≥5% of patients in either treatment group.

  • 3

    Fisher's exact test.

Most common AEs1
Anemia43 (41.0)54 (50.5)0.171
Diarrhea28 (26.7)30 (28.0)0.878
Urinary tract infection28 (26.7)27 (25.2)0.876
Hypertension25 (23.8)19 (17.8)0.312
Constipation19 (18.1)20 (18.7)1.000
Complications of transplanted kidney18 (17.1)20 (18.7)0.858
Hyperglycemia17 (16.2)14 (13.1)0.564
Hyperkalemia15 (14.3)17 (15.9)0.848
Tremor16 (15.2)8 (7.5)0.086
AEs of special interest2
CMV infection9 (8.6)6 (5.6)0.434
BK virus infection3 (2.9)8 (7.5)0.214
CMV viremia6 (5.7)2 (1.9)0.168
SAEs2
Abnormal histology6 (5.7)11 (10.3)0.312
CMV infection9 (8.6)6 (5.6)0.434
Complications of transplanted kidney8 (7.6)8 (7.5)1.000
Renal impairment4 (3.8)8 (7.5)0.374
BK virus infection3 (2.9)8 (7.5)0.214
Urinary tract infection2 (1.9)6 (5.6)0.280
Cardiac disorder AEs
Hypertension25 (23.8)19 (17.8)0.312
Tachycardia6 (5.7)1 (0.9)0.064
Sinus tachycardia2 (1.9)0 (0)0.244

The overall types of SAEs were generally similar in both treatment groups (Table 4). Cardiac AEs were reported in 10.5% of patients in the alefacept group and 10.3% of patients in the placebo group, but hypertension (23.8% vs. 17.8%), tachycardia (5.7% vs. 0.9%) and sinus tachycardia (1.9% vs. 0%) were reported more frequently with alefacept than with placebo. Fewer patients treated with alefacept developed NODAT compared with patients treated with placebo (14.4% vs. 21.3%) but the difference did not reach statistical significance (p = 0.213). The overall incidence of malignancies was higher in the alefacept group compared with the placebo group (5.7% vs. 0.9%; p = 0.06, Table 5). One patient died during the study as a result of malignancy (malignant lung neoplasm in the alefacept group). One additional event of lymphoma occurred in a placebo treated subject on Day 219. This event is not shown in Table 5 as it occurred beyond the end of study (Day 182) utilized for the safety analysis. Including this subject, the overall incidence of malignancy was 1.9% versus 5.7% in the placebo and alefacept groups respectively (p = 0.17). None of the malignancy events were assessed as being related to study medication.

Table 5. Malignant neoplasms
EventN (%)Description
  • PTLD, posttransplant lymphoproliferative disorder.

  • 1

    p-Value = 0.06 (Fisher exact test).

Placebo (n = 107)
Any1 (0.9%) 
Colon cancer with metastasis 53-year-old female
  Day 10, acute rejection treated with steroids
  Day 112, initial diagnosis colon cancer with hepatic metastasis
Alefacept (n = 105)
Any6 (5.7%)1 
Basal cell carcinoma 54-year-old male
  Received all alefacept doses
  Day 162, basal cell carcinoma diagnosed
Cervix carcinoma 38-year-old female
  Received all alefacept doses except Day 56, Day 77 and Day 84
  Day 11, acute rejection treated with steroids
  Day 54, cervical carcinoma diagnosed
Lung neoplasm malignant 54-year-old male
  Past medical history of heavy smoking for 37 years
  Received all alefacept doses
  Day 115, small cell lung carcinoma diagnosed
Pheochromocytoma malignant 38-year-old male
  Past medical history of pheochromocytoma: neck and retro-cardiac
  Alefacept received only on Day 0
  Day 24, recurrent pheochromocytoma in neck and retro-cardiac
Lymphoproliferative disorder (PTLD) 25-year-old male
  Received all alefacept doses
  Valganciclovir prophylaxis
  EBV serology pretransplant, donor unknown/recipient negative
  Day 183, PTLD diagnosed
  Day 201 EBV viremia documented
Tumor left kidney 53-year-old male
  Past medical history of polycystic kidney disease
  Received all alefacept doses
  Day 90, tumor left polycystic kidney diagnosed
  Pathology showed Grade 2 renal cell carcinoma in left native kidney

There were four deaths in the study, one in the alefacept group (pulmonary carcinoma) and three in the placebo group (two cases of septic shock, one of acute pulmonary edema). None of the deaths were deemed related to study treatment by the investigators.

There were no clinically meaningful differences in laboratory parameters or vital signs. The incidence of low CD4+ counts (<250 cells/µL) was 38.6% in the alefacept group compared with 31.7% in the placebo group.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

This is the first clinical study to investigate the effects of adding alefacept to combination therapy with tacrolimus, MMF and corticosteroids for the prevention of acute rejection in de novo kidney transplantation. Alefacept was not statistically significantly superior to placebo for the primary endpoint (incidence of T cell mediated BCAR within 6 months), or for any of the secondary endpoints including patient and graft survival, DGF, efficacy failure and renal function in this population. Although alefacept was pharmacologically active, the impact of alefacept on memory T cell depletion was delayed until Week 3 after most BCAR episodes had occurred. The CD2 molecule undergoes a conformational state change on cell activation [9-11]. As the expression level of CD2 increases with cell activation, the proportion of altered conformers also increases [9]. Although it is possible that heterogeneity of subject's expression of CD2 conformers may play a role in the effectiveness of alefacept, in vitro binding data argue against the presence of multiple cell activation-dependent affinity states of CD2 for LFA-3 binding [12].

In preclinical models alefacept monotherapy has been shown to significantly prolong baboon cardiac allograft survival [13] and, in combination with CTLA4-Ig/sirolimus has shown efficacy in prolonging renal allograft survival in rhesus models of renal transplantation [14]. However, a recent report showing a negative impact of alefacept in combination with belatacept/sirolimus [15] suggests that alefacept effectiveness may vary on inclusion in different combination therapy regimens.

Alefacept was associated with a good safety and tolerability profile that was generally similar to that observed in the placebo group. There were no differences in the overall incidence of SAEs, infections or cardiac disorders between the two groups, although there were some differences in the types of infection or cardiac disorder reported. For example, CMV infections were more common with alefacept and BK viral infections were more common with placebo. There were more malignancies in the alefacept-treatment group compared with the placebo group. However, the clinical circumstances of individual events make attribution to study drug unclear. The only case of PTLD in the study occurred in a patient receiving alefacept who was EBV negative serologically at baseline (Table 5). An increased incidence of PTLD has been reported in renal transplant patients receiving efalizumab, a biologic targeting LFA-1 which also has increased expression in memory T cells [16]. Neither alefacept nor efalizumab have been associated with occurrence of PTLD in psoriasis [4, 5, 17, 18].

In conclusion, no clear efficacy benefit was shown for the addition of alefacept to the standard triple immunosuppressive regimen of tacrolimus, MMF and corticosteroids in this population of de novo renal transplant recipients. However, alefacept successfully depleted memory T cells and this approach to immunosuppression remains relevant at a conceptual level. These findings warrant further investigation of agents targeting memory T cells in well-designed, prospective clinical trials of renal transplantation.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

The design and results of this study have been presented previously in abstracts at the American Transplant Congress, in Philadelphia, PA, USA, 2011 and the European Society for Organ Transplantation, in Glasgow, UK, 2011.

This study and statistical analyses were supported by Astellas Pharma US, Inc., Deerfield, IL, USA.

The authors would like to thank Tamsin Williamson and Michelle Seymour, professional medical writers from UBC-Envision Group, for their assistance in drafting and revising the manuscript.

The manuscript has been compiled in accordance with the CONSORT guidelines.

Disclosures

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

The authors of this manuscript have conflicts of interest to disclose as described by the American Journal of Transplantation: Professor Rostaing has received honorariums from Astellas for speaking engagements. Professor Charpentier has no conflicts of interest to disclose. Professor Glyda has no conflicts of interest to disclose. Professor Rigotti has acted as a consultant or has received speaker fees for Astellas. Ms Hettich and Drs Franks, Houbiers, First and Holman are full-time employees of Astellas Pharma Global Development.

Appendix

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References

The authors would like to thank the 27 investigators who participated in this study, of whom 21 have given permission to be acknowledged, as follows: in Austria, Ferdinand Mühlbacher, AKH, Medical University of Vienna, Vienna; in Belgium, Daniel Abramowicz, Hôpital Universitaire Erasme, Brussels; Patrick Peeters, Ghent University Hospital, Ghent; Yves Vanrenterghem, University Hospital KU Leuven, Leuven; in the Czech Republic, Stefan Vitko, IKEM Transplantcentre, Prague; in France, Diego Cantarovich, ITUN, Nantes University Hospital, Nantes; Georges Mourad, Hôpital Lapeyronie, Montpellier; Philippe Lang, Hôpital Henri Mondor, Creteil; Elisabeth Cassuto-Viguier, Hôpital Pasteur, Nice; Christophe Legendre, Universite Paris Descartes & Hôpital Necker, Paris; in Germany, Bernhard Banas, University Hospital Regensburg, Regensburg; in Italy, Mario Carmellini, Azienda Ospedaliera Universitaria Senese, Siena; Sergio Stefoni, Policlinico Universitario S. Orsola-Malpighi di Bologna, Bologna; in Poland, Marek Ostrowski, Samodzielny Publiczny Szpital Kliniczny 2, Szczecin, Zbigniew Wlodarczyk, Szpital Uniwersytecki CM UMK, Bydgoszcz; in Spain, Federico Oppenheimer, Hospital Clínic de Barcelona, Barcelona; Manuel Arias, Hospital Universitario Marques de Valdecilla, Santander; Josep Grinyo, Hospital Universitari de Bellvitge, Hospitalet de Llobregat; in Sweden, Jan Wahlberg, Akademiska Sjukhuset, Uppsala; in The Netherlands, Johannes van Hooff, Maastricht University Medical Centre, Maastricht; in the UK, Tunde Campbell, Manchester Royal Infirmary, Manchester.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. Disclosures
  9. Appendix
  10. References