Pharmacotherapeutic group: Immunosuppressants, selective immunosuppressants, ATC code: L04AA28.
Belatacept, a selective costimulation blocker, is a soluble fusion protein consisting of a modified extracellular domain of human cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) fused to a portion (hinge-CH2-CH3 domains) of the Fc domain of a human immunoglobulin G1 antibody. Belatacept is produced by recombinant DNA technology in a mammalian cell expression system. Two amino acid substitutions (L104 to E; A29 to Y) were made in the ligand binding region of CTLA-4.
Mechanism of action
Belatacept binds to CD80 and CD86 on antigen presenting cells. As a result, belatacept blocks CD28 mediated co-stimulation of T cells inhibiting their activation. Activated T cells are the predominant mediators of immunologic response to the transplanted kidney. Belatacept, a modified form of CTLA4-Ig, binds CD80 and CD86 more avidly than the parent CTLA4-Ig molecule from which it is derived. This increased avidity provides a level of immunosuppression that is necessary for preventing immune-mediated allograft failure and dysfunction.
Pharmacodynamic effects
In a clinical study, approximately 90% saturation of CD86 receptors on the surface of antigen-presenting cells in the peripheral blood was observed following the initial administration of belatacept. During the first month post-transplantation, 85% saturation of CD86 was maintained. Up to month 3 post-transplantation with the recommended dosing regimen, the level of CD86 saturation was maintained at approximately 70% and at month 12, approximately 65%.
Clinical efficacy and safety
Study 1 and 2: Phase 3 studies in newly transplanted patients
The safety and efficacy of belatacept as part of an immunosuppressive regimen following renal transplantation were assessed in two randomised, partially-blinded, multicentre, 3 year studies with the primary endpoint specified at Year 1. These studies compared two dose regimens of belatacept (MI and LI) with ciclosporin in recipients of standard criteria (Study 1) or extended criteria (Study 2) donor organs. All patients received basiliximab, MMF, and corticosteroids. The more intensive (MI) regimen, which included higher and more frequent dosing during the first 6 months post transplant, resulted in 2-fold higher exposure to belatacept than the less intensive (LI) regimen during Months 2 through 7 post transplant. Efficacy was similar between MI and LI while the overall safety profile was better for the LI. Therefore, the recommended dose of belatacept is the LI dosage regimen.
Study 1: Recipients of Living Donor and Standard Criteria Deceased Donor Kidneys
Standard criteria donor organs were defined as organs from a living donor, or a deceased donor with anticipated cold ischemia time of < 24 hours and not meeting the definition of extended criteria donor organs. Study 1 excluded (1) recipients undergoing a first transplant whose current PRA were ≥50%; (2) recipients undergoing a retransplantation whose current PRA were ≥30%; (3) recipients when previous graft loss was due to acute rejection and in case of a positive T-cell lymphocytotoxic cross match.
In this study, 666 patients were enrolled, randomised, and transplanted; 219 to belatacept MI, 226 to belatacept LI, and 221 to ciclosporin. The median age was 45 years; 58% of donor organs were from living patients; 3% were re-transplanted; 69% of the study population was male; 61% of patients were white, 8% were black/African-American, 31% were categorised as of other races; 16% had PRA ≥ 10%; and 41% had 4 to 6 HLA mismatches.
The dose of corticosteroids used in all treatment groups was tapered during the first 6 months following transplantation. The median corticosteroid doses administered with the belatacept-recommended regimen up to months 1, 3, and 6 were 20 mg, 12 mg and 10 mg, respectively.
Study 2: Recipients of Extended Criteria Donor Kidneys
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 after cardiac death or (4) anticipated cold ischemia time of ≥ 24 hours. Study 2 excluded recipients with a current PRA ≥ 30%, re-transplanted patients, and in case of a positive T-cell lymphocytotoxic cross match.
In this study, 543 patients were enrolled, randomised, and transplanted; 184 to belatacept MI, 175 to belatacept LI, and 184 to ciclosporin. 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 categorised as of other races; 3% had PRA ≥ 10%; and 53% had 4 to 6 HLA mismatches.
The dose of corticosteroids used in all treatment groups was tapered during the first 6 months following transplantation. The median corticosteroid doses administered with the belatacept-recommended regimen up to months 1, 3, and 6 were 21 mg, 13 mg and 10 mg, respectively.
Table 5 summarises results for belatacept LI compared with ciclosporin for the co-primary efficacy endpoints of death and graft loss, composite renal impairment, and acute rejection (defined as clinically suspected biopsy proven acute rejection). Patient and graft survival were similar between belatacept and ciclosporin. Fewer patients met the composite renal impairment endpoint and mean GFR was higher with belatacept compared to ciclosporin.
Acute rejection (AR) occurred more frequently with belatacept versus ciclosporin in Study 1 and with similar frequency with belatacept versus ciclosporin in Study 2. Approximately 80% of AR episodes occurred by Month 3 and were infrequent after Month 6. In Study 1, 11/39 belatacept and 3/21 ciclosporin acute rejections were Banff 97 grade ≥ IIb by Year 3. In Study 2, 9/33 belatacept and 5/29 ciclosporin acute rejections were Banff 97 grade ≥ IIb by Year 3. AR was treated more often with lymphocyte depleting therapy (a risk factor for PTLD; see section 4.4) in the belatacept group than the ciclosporin group. In both studies, in patients with AR by Year 2, donor-specific antibodies, one of the criteria for diagnosis of antibody-mediated rejection, were present in 6% (2/32, Study 2)-8% (3/39, Study 1) and 20% (4/20, Study 1)-26% (7/27, Study 2) in the belatacept and ciclosporin groups by year 3, respectively. By Year 3 recurrent AR was similar across groups (< 3%) and subclinical AR identified on the 1 year protocol biopsy was 5% in both groups. In Study 1, 5/39 belatacept patients versus 1/21 ciclosporin patients with AR had experienced graft loss, and 5/39 belatacept patients and no ciclosporin patients with AR had died by Year 3. In Study 2, 5/33 belatacept patients versus 6/29 ciclosporin patients with AR had experienced graft loss, and 5/33 belatacept patients versus 5/29 ciclosporin patients with AR had died by Year 3. In both studies, mean GFR following AR was similar in belatacept and ciclosporin-treated patients.
| Table 5: Key efficacy outcomes at years 1 and 3 |
| | Study 1: living and standard criteria deceased donors | Study 2: extended criteria donors |
| Parameter | Belatacept LI | Ciclosporin | Belatacept LI | Ciclosporin |
| | N = 226 | N = 221 | N = 175 | N = 184 |
| Patient and Graft Survival (%) Year 1 [95% CI] | 96.5 [94.1-98.9] | 93.2 [89.9-96.5] | 88.6 [83.9-93.3] | 85.3 [80.2-90.4] |
| Year 3 [95% CI] | 92.0 [88.5-95.6] | 88.7 [84.5-92.9] | 82.3 [76.6-87.9] | 79.9 [74.1-85.7] |
| Death (%) Year 1 | 1.8 | 3.2 | 2.9 | 4.3 |
| Year 3 | 4.4 | 6.8 | 8.6 | 9.2 |
| Graft Loss (%) Year 1 | 2.2 | 3.6 | 9.1 | 10.9 |
| Year 3 | 4.0 | 4.5 | 12.0 | 12.5 |
| % of Patients meeting Composite renal impairment endpoint at Year 1a | 54.2 | 77.9 | 76.6 | 84.8 |
| P-value | < 0.0001 | - | < 0.07 | - |
| AR (%) Year 1 (%) [95% CI] | 17.3 [12.3-22.2] | 7.2 [3.8-10.7] | 17.7 [12.1-23.4] | 14.1 [9.1-19.2] |
| Year 3 (%) [95% CI] | 17.3 [12.3-22.2] | 9.5 [5.6-13.4] | 18.9 [13.1-24.7] | 15.8 [10.5-21.0] |
| Mean Measured GFRb ml/min/1.73 m2 Year 1 | 63.4 | 50.4 | 49.6 | 45.2 |
| Year 2 | 67.9 | 50.5 | 49.7 | 45.0 |
| Mean Calculated GFRc ml/min/1.73 m2 Month 1 | 61.5 | 48.1 | 39.6 | 31.8 |
| Year 1 | 65.4 | 50.1 | 44.5 | 36.5 |
| Year 2 | 65.4 | 47.9 | 42.8 | 34.9 |
| Year 3 | 65.8 | 44.4 | 42.2 | 31.5 |
a Proportion of Patients with Measured GFR < 60 ml/min/1.73 m2 or with a Decrease in Measured GFR ≥ 10 ml/min/1.73 m2 from Month 3 to Month 12.
b Measured GFR was assessed by iothalamate at Year 1 and 2 only
c Calculated GFR was assessed by MDRD formula at Month 1, Years 1, 2, and 3
Progression of Chronic Kidney Disease (CKD) Staging
In Study 1 by Year 3, mean calculated GFR was 21 ml/min/1.73 m2 higher with belatacept, and 10% and 20% of patients reached CKD stage 4/5 (GFR < 30 ml/min/1.73 m2) with belatacept versus ciclosporin, respectively. In Study 2 by Year 3, mean calculated GFR was 11 ml/min/1.73 m2 higher with belatacept, and 27% and 44% of patients reached CKD stage 4/5 (GFR < 30 ml/min/1.73 m2) with belatacept versus ciclosporin, respectively.
Chronic Allograft Nephropathy/Interstitial Fibrosis and Tubular Atrophy (IFTA)
The prevalence of CAN/IFTA at Year 1 in Studies 1 and 2, was numerically lower with belatacept than ciclosporin (~ 9.4% and 5%, respectively).
New Onset Diabetes Mellitus and Blood Pressure
In a prespecified pooled analysis of Studies 1 and 2 at Year 1, the incidence of new onset diabetes mellitus (NODM), defined as use of an antidiabetic agent for ≥ 30 days or ≥ 2 fasting plasma glucose values > 126 mg/dl (7.0 mmol/l) post-transplantation, was 5% with belatacept and 10% with ciclosporin. At Year 3, the incidence of NODM was 8% with belatacept and 10% with ciclosporin.
For Studies 1 and 2 at Years 1 and 3, belatacept was associated with 6 to 9 mmHg lower mean systolic blood pressure, approximately 2 to 4 mmHg lower mean diastolic blood pressure, and less use of antihypertensive medicinal products than ciclosporin.
Long-term extension in Study 1 and Study 2
A total of 321 belatacept (MI: 155 and LI: 166) and 136 ciclosporin patients completed 3 years of treatment in Study 1 and entered the 4-year long-term open label extension period (up to 7 years in total). More patients discontinued in the ciclosporin group (32.4%) versus each belatacept group (17.4% and 18.1% in MI and LI groups, respectively) during the long-term extension period. A total of 217 belatacept (MI: 104 and LI: 113) and 87 ciclosporin patients completed 3 years of treatment in Study 2 and entered the 4-year long-term open label extension period (up to 7 years in total). More patients discontinued in the ciclosporin group (34.5%) versus each belatacept group (28.8% and 25.7% for MI and LI groups, respectively) during the long-term extension period.
As compared to ciclosporin and assessed by the hazard ratio (HR) estimates (for death or graft loss) from an ad hoc Cox regression analysis, overall patient and graft survival was higher for belatacept-treated patients in Study 1, HR 0.588 (95% CI: 0.356-0.972) for the MI group and HR 0.585 (95% CI: 0.356-0.961) for the LI group, and comparable across treatment groups in Study 2, HR 0.932 (95% CI: 0.635-1.367) for the MI group and HR 0.944 (95% CI: 0.644-1.383) for the LI group. The overall proportion of patients with death or graft loss was lower in belatacept-treated patients (MI: 11.4%, LI: 11.9%) as compared to ciclosporin-treated patients (17.6%) in Study 1. The overall proportion of patients with death or graft loss was comparable across treatment groups (29.3%, 30.9%, and 28.3% for MI, LI and ciclosporin, respectively) in Study 2. In Study 1, in the MI, LI, and ciclosporin groups, respectively, death occurred in 7.8%, 7.5%, and 11.3% of patients, and graft loss occurred in 4.6%, 4.9%, and 7.7% of patients. In Study 2, in the MI, LI, and ciclosporin groups, respectively, death occurred in 20.1%, 21.1%, and 15.8% of patients, and graft loss occurred in 11.4%, 13.1%, and 15.8% of patients. The higher proportion of deaths in the LI group in Study 2 was mainly due to neoplasms (MI: 3.8%, LI: 7.1%, ciclosporin: 2.3%).
The higher calculated GFR observed in belatacept-treated patients relative to ciclosporin-treated patients during the first 3 years was maintained over the long-term extension period. In Study 1, mean calculated GFR at 7 years was 74.0, 77.9 and 50.7 mL/min/1.73 m² in the belatacept MI, belatacept LI and ciclosporin groups, respectively. In Study 2, mean calculated GFR at 7 years was 57.6, 59.1 and 44.6 mL/min/1.73 m², in the same groups, respectively. The time to death, graft loss, or GFR <30 mL/min/1.73 m² was analyzed over the 7-year period: in Study 1, approximately 60% reduction in the risk of death, graft loss, or GFR <30 mL/min/1.73 m² was observed among patients in the belatacept groups as compared with those assigned to ciclosporin. In Study 2, approximately 40% reduction in this risk was observed among patients in the belatacept groups as compared with those assigned to ciclosporin.
Conversion from calcineurin inhibitor (CNI)-based to belatacept-based regimen
Conversion Study 1:
A total of 173 kidney transplant recipients on a CNI-based maintenance regimen (ciclosporin; CsA: 76 patients or tacrolimus; TAC: 97 patients), who had received a renal allograft from a living or deceased donor at 6 to 36 months prior to study participation, were enrolled in a multicentre, prospective, randomised, open-label trial. Patients with a history of treatment for biopsy proven acute rejection (BPAR) within 3 months prior to study participation, recurrent BPAR, Banff grade IIA or higher cellular rejection, or antibody mediated rejection with the current allograft; loss of a previous allograft due to BPAR; or a positive T-cell lymphocytotoxicity cross match at the time of the current transplant were considered to be at higher immunological risk and were excluded from the study. Patients were randomised 1:1 to either continue on their CNI-based regimen or convert to a belatacept-based regimen. During the conversion phase, a maintenance dose of belatacept was administered on Day 1 and every two weeks for the first 8 weeks (see Section 4.2). The CNI dose was gradually tapered between Day 1 and Day 29: On day 1 patients received 100% of CNI dose, followed by 40-60% on day 15, 20-30% on day 23, and none on day 29. Following the initial, 8-week conversion phase, a maintenance dose of belatacept was administered every 4 weeks thereafter, beginning at 12 weeks after the first dose (see Section 4.2). The study duration was 12 months, with a long-term extension (LTE) period from Month 12 to Month 36. The primary (descriptive) endpoint was renal function (change in eGFR from baseline) at 12 months.
At Month 12, all of 84 patients (100%) in the belatacept conversion group and 98.9% (88/89) patients in the CNI continuation group had survived with a functioning graft. BPAR was reported in 7.1% (6/84) patients in the belatacept conversion group and none in the CNI continuation group. Of the 81 patients in each group who entered the LTE period (ITT-LT subpopulation), 97% (79/81) in the belatacept conversion and 98.8% (80/81) in the CNI continuation group had survived with a functioning graft by Month 36. One case of BPAR was reported in the belatacept conversion group and three cases of BPAR were reported in the CNI continuation group during the LTE period; in the ITT-LT subpopulation up to 36 months, BPAR was reported in 6.2% (5/81) vs 3.7% (3/81) of patients in the belatacept conversion vs CNI continuation groups, respectively. None of the BPAR events was of Banff grade III severity. One patient in each group with BPAR experienced subsequent graft loss. At Month 12, the mean (SD) change in cGFR from baseline was +7.0 (12.0) mL/min/1.73 m2 in the belatacept conversion group (N=84) as compared to +2.1 (10.3) mL/min/1.73 m2 in the CNI continuation group (N=89). By Month 36, the mean change from baseline cGFR was +8.2 (16.1) mL/min/1.73 m2 in the belatacept conversion group (N=72) and +1.4 (16.9) mL/min/1.73 m2 in the CNI continuation group (N=69).
Conversion Study 2:
A total of 446 kidney transplant patients on a CNI-based maintenance regimen (CsA: 48 patients or TAC: 398 patients), who had received a renal allograft from a living or deceased donor at 6 to 60 months prior to study participation, were enrolled in a multicentre, prospective, randomised, open-label trial. Patients with a history of treatment for biopsy proven acute rejection (BPAR) within 3 months prior to study participation, recurrent BPAR, Banff grade IIA or higher cellular rejection, or antibody mediated rejection with the current allograft; loss of a previous allograft due to BPAR; or a positive T-cell lymphocytotoxicity cross match at the time of the current transplant were considered to be at higher immunological risk and were excluded from the study. Patients were randomised 1:1 to either continue on their CNI-based regimen or convert to a belatacept-based regimen. The CNI tapering and belatacept conversion phase followed a similar regimen as Conversion Study 1 (see above). The study duration was 24 months. The primary (descriptive) composite endpoint was the proportion of subjects who survived with a functioning graft at Month 24.
The proportion of patients surviving with a functioning graft was similar in the belatacept conversion (98.2%; 219/223) and CNI continuation (97.3%; 217/223) groups at Month 24. Four patients (1.8%) in each group had died and two (0.9%) in the CNI continuation group had lost a graft. At Month 12, BPAR was reported for 18/223 patients (8.1%) in the belatacept conversion group and 4/223 patients (1.8%) in the CNI continuation group. At Month 24, there were no further cases of BPAR in the belatacept conversion group, but 5 additional cases were reported in the CNI continuation group (total of 9/223 (4%) at Month 24). The majority of the BPAR cases reported in the belatacept conversion group occurred during the first 6 months; all were successfully treated with no subsequent graft loss. The overall severity of BPAR events was greater following belatacept conversion compared to those in the CNI continuation group. When analysed with imputation to zero for death and graft loss, values for adjusted mean cGFR at Month 24 were 55.5 and 48.5 mL/min/1.73 m2 in the belatacept conversion and CNI continuation groups, respectively. The corresponding adjusted change from baseline cGFR values were +5.2 and -1.9 mL/min/1.73 m2, respectively.
Phase 2 liver transplant study
A single, randomised, multi-centre, controlled Phase 2 trial of belatacept in de novo orthotopic liver transplant recipients was conducted. A total of 250 subjects were randomised to 1 of 5 treatment groups (3 belatacept and 2 tacrolimus groups). The belatacept dosing used in this liver study was higher in all 3 belatacept arms than the belatacept dosing used in the Phase 2 and 3 renal transplant studies.
An excess in mortality and graft loss was observed in the belatatacept LI + MMF group and an excess in mortality was observed in the belatacept MI + MMF group. No pattern was identified in the causes of death. There was an increase in viral and fungal infections in the belatacept groups versus the tacrolimus groups, however overall frequency of serious infections was not different among all treatment groups (see section 4.4).
Elderly
Two hundred seventeen (217) patients 65 years and older received belatacept across one Phase 2 and two Phase 3 renal studies.
Elderly patients demonstrated consistency with the overall study population for safety and efficacy as assessed by patient and graft survival, renal function, and acute rejection.
Paediatric population
The licensing authority has deferred the obligation to submit the results of studies with belatacept in one or more subsets of the paediatric population in renal transplantation (see section 4.2 for information on paediatric use).