This document discusses co-stimulation blockade using the drug Belatacept as an immunosuppressive treatment for renal allograft rejection. It summarizes results from two key clinical trials comparing Belatacept to cyclosporine. The Phase II trial found similar acute rejection rates at 6 months between Belatacept and cyclosporine, but Belatacept was associated with better renal function and lipid/blood pressure levels. The Phase III trial also found similar patient and graft survival between Belatacept and cyclosporine, but Belatacept was associated with better renal function despite a higher rate of acute rejection episodes. Both trials demonstrated Belatacept's potential to preserve renal function compared to calcineurin inhibitors like

1. Co- Stiumulation Blockadeand the allograft ItiYadav, MD HOFSTRA NORTH SHORE LIJ SCHOOL OF MEDICINE

2. Main Causes of Renal Allograft Loss

3. ACUTE RENAL ALLOGRAFT REJECTION A process by which the immune system of the recipient of a transplant attacks the transplanted organ or tissue This is the normal response of the healthy human immune system, which can distinguish foreign tissues and attempts to destroy them Mediated by activated T lymphocytes Activation occurs following recognition of graft Ag directly or after being processed & presented by APC At least one episode of acute rejection occurs in 62% of patients t/t with CsA, AZA and Steroids Less common with newer immunosuppressants

6. High Risk For AMR

8. Classic Vascular Uncommon Severe Necrotizing arteritis Arterial mural fibrinoid necrosis Variable inflammation( Neutr/Lymp/Mono) Monocyte infiltration of GC & PTC ( detected by CD68 staining) more sensitive Severely damaged endothelial cells Luminal thrombosis common Typically cortical infarction +focal interstitial hemorrhage rather than tubulitis

9. Neutrophil infiltrates in peritubular capillaries Histology not a sensitive/specific diagnostic tool for acute humoral rejection as are methods to detect DSA/C4d

10. Non Vascular More frequent form C4d is covalently bound to peritubular capillary endothelium/BM collagen C4d can be +ve in glomerular mesangium,glomerular BM,tubular BM & arterioles in both native and transplanted kidney Diffuse peritubular capillary (PTC) C4d has only been described in renal allografts (Cause of this specificity ?) Diagnosis by immunostaining for C4d,Best seen on Frozen sections Despite association of C4d with IC deposition ,IG has not been detectable in same areas (endothelial cells might be dislodging surface Ab, C4d resists modulation d/t covalent binding to tissue) Scattered glomerular ,peritubular capillary and TI neutrophils ,ATN +/-

12. C4d in peritubular capillaries C4d -footprint of humoral rejection Can be evident within one hr of transplantation Marker of complement activation generated by presence of Ab-Ag complexes Strong linear widespread peritubular capillary staining to be called a positive N Kidneys detectable in glomerular mesangium, vascular pole

13. Correlation b/w +C4d staining, DSA & h/p findings Indication allograft biopsies pts with circulating DSA & H/p findings of neutrophils in PTC/fibrinoid necrosis - diffuse PTC C4d + seen in 100% biopsies 37% with steroid resistant rejection had DSA and 95% of these had C4d in PTC C4d -95% Sensitive & 96% specific for presence of DSA Graft loss higher in Ab mediated rejection(~40%) esp if associated with arteritis than with cellular rejection(~7%) Inferior graft survival with circulating DSA and C4d +ve as compared to positive DSA alone

15. c4d Unclear duration of persistence Disappearance has been reported on repeat biopsies 2-3 weeks after DSA no longer detectable Perfect correlation b/w positive staining and DSA does not occur Non HLA Ab (AG II receptor A/Antiendothelial Ab) can l/t C4d deposition Circulating DSA can be below level of detection Positive DSA >sensitive assays with –ve C4d staining d/t DSA which is non complement activating (clinically insignificant)

16. Differential Diagnosis AMR Systemic necrotizing arteritis( recurrence of vascular lesions in transplant rare) Arterial occlusion from surgical causes- ligation of artery or embolization C4d staining in renal allograft other causes Simultaneous occurrence of Ab mediated & Cellular (Mixed) may be common

17. Therapeutic options IVIG Plasmapheresis Selective Immunoadsorption Antilymphocyte Therapy Altered Maintenance Immunosuppressants Combination of above Addition of t/t targeting simultaneous Cellular rejection (Steroids/Anti-lymphocyte) as they may down regulate B cell response via decrease in activity of helper T cells

18. IVIG Optimal Quantities and MOA poorly defined Proposed mechanisms-Suppression of IG synthesis -Altered Complement binding -Inhibition of Complement activation

19. PLasmapheresis Removes Ab present in circulation No effect on further AB production Alone may stimulate a rebound IG production Need determined based on -preexisting Ab titer -affinity of Ab to Ag -quantity of IVIG given -use of adjunct agents Initial t/t 1-1.5 volume exchange Alternate day exchange protocol preferable as allows for interval recovery PT/PTT & fibrinogen to acceptable levels w/o need for FFP thereby minimizing sensitization Usually carried until S Cr is within 20-30% of previous baseline for min 4 t/t sessions

20. Switch to MMF & Tacrolimus regimen If already on above, augment dose Methylprednisolone for 3-5 days with rapid taper to maintenance dosing Monitor DSA: 50% reduction associated with improved graft survival

21. CNI’s affect broad range of non immunologic targets Associated with worsening HTN,DM & DYSLIPIDEMIA Contributing to increased CV morbidity & mortality MC cause death among transplant recipients 1yr post transplant

22. Investigational Immunosuppression Belatacept(LEA29Y)-Fusion Protein with mutated high affinity receptor for B7-1& B7-2 and LEA29Y portion of IG molecule Eculizimab-Complement inhibitory monoclonal Ab inhibits assembly of MAC Alefacept-Humanized LFA-3-Ig targeting T memory cells Voclosporine-Isomeric Cyclosporine ( >potent) Sotrastaurin-Protein kinase C inhibitor targeting T cell activation Tasocitinib-Jak 3 inhibitor selective reduction NK and T cell subsets Bortozemib-inhibitor of 26S proteosome Photopheresis-Peripheral Lymphocytes collected exposed to UV light to down regulate T cell clones

23. T-Cells Require Co stimulation for Full Activation

24. BelataceptFirst in class Selective costimulation blocker Bristol-Myers Squibb Fusion protein composed of Fc fragment of human IgG1 linked to extracellular domain of CTLA-4 which is molecule crucial for T-cell costimulation Binds surface ligands CD80 & CD86 of APC & blocks costimulatory pathway for T cell activation Blockade of signal 2 inhibits T-cell activation, promoting anergy,apoptosis Derived from Abatacept (Orencia) but Differs by only 2 AA Conferring greater binding avidity to CD80 & CD86, more potent inhibition of T-cell activation, effective rejection prophylaxis Rejection prophylaxis in transplantation Designed to avoid nephrotoxicity & increased cardiovascular and metabolic risks associated w CNI

25. Belatacept blocks T-cell activation

26. Phase II ,Randomized, multicenter Trial,22 centers US, Canada & Europe Compared Belatacept to Cyclosporine for prevention of Acute rejection and protection of renal function N=218(74 MI B,71 LI B,73 CsA) Acute rejection defined as Histologic evidence + at least 0.5 mg/dl rise in S. Cr above baseline All received Basiliximab,MMF, Steroids as induction agents Vincenti,Larsen NEJM 2005 353:770

28. Most (N193) Low-risk patients (89%) Patients receiving 1st renal transplant Patients with a history of panel reactive Ab titer ≤20% Patients at low risk for acute rejection (investigator determined)

29. At 6mo Acute rejection rates similar(7%MI ,6% LI ,8% CsA) Biopsy proven! Investigator treated rejection 26%-LI 29%-MI Belatacept 16%-Cyclosporine At 12mo GFR significantly higher with both Belatacept groups Lipid levels/BP lower in Belatacept despite greater use of hypolipidemic therapy in CsA t/t gp CAN less common with both Belatacept groups Incidence of infection similar ( UTI, CMV) Target trough levels CsA high(150-300ng/ml)contributed to development of CAN in CsA group Vincenti,Larsen NEJM 2005 353:770

30. PTLD Incidence 6% MI 0%LI & Cyclosporine groups Cancer occurrence N=2 MI Belatacept (one breast cancer, one PTLD) N=0 LI Belatacept( ? dose related occurrence) N=2 CsA(one skin cancer,one thyroid cancer) PTLD developed in 2 additional patients t/t with MI regimen @ 2 &13 mo after belatacept had been replaced with conventional immunosuppression 2/3 patients PTLD primary EBV infection The 3rd pt received OKT3 for acute rejection, belatacept had been discontinued before this therapy with PTLD developing >12 mo later Rate of cancer with belatacept consistent with estimated incidence(3.3%) for non dermatologic cancers at 1Yr in transplant population

31. CONCLUSIONS Not inferior to CsA in preventing AR May preserve GFR May reduce rate of CAN Results of Extension of this trial for another 4 years (voluntary enrollment of ~ 50% patients) GFR remained stable with Belatacept PTLD in one pt t/t with CsA, none with Belatacept Serious GI disorders more common with Belatacept (12 Vs. 8%) Vincenti,Larsen NEJM 2005 353:770

32. Included adult(>18yrs) recipients of a living/deceased-donor kidney Cold ischemia time < 24hrs 3-yr, randomized, controlled, parallel-group, multicenter Phase III study conducted at 100 centers worldwide (N 686) Assessed MI or LI regimen of Belatacept Vs.CsA (Trough levels 100-250ng/ml) Excluded: -Recipients of ECD kidneys -Prior/concurrent non renal solid organ transplants -First-time patients with PRA>50%/Retransplants with PRA>30% Each patient treated with Basiliximab induction, MMF & CS Vincenti, Am J Transplantation 2010:535

35. composite renal impairment endpoint

36. incidence of acute rejectionOverall patient and graft survival with a functioning kidney were similar across the treatment groups-86% MI, 88% LI,85% CsA GFR better with Belatacept(65 vs. 63 vs. 50ml/min) Despite Belatacept gp higher incidence & grade of acute rejection episode (22% MI,17% LI,7% CsA)

37. Presence of T reg cells in acute rejection infiltrates has been proposed to impart improved outcomes Graft biopsies in Belatacept t/t patients have significantly greater number FOXP3(+) T reg cells during acute rejection compared with CNI t/t patients

40. First 12 mo malignancy incidence MI (5) LI(4) CsA(1) (excluding non melanoma skin cancer) First 12 mo PTLD MI(1) LI(2) CsA(1) 2 additional in MI gp after 12 mo (both involved CNS) More common with Belatacept 5 vs. 1 CsA gp 4 of total 6 PTLD cases had risk factors EBV negative serology Similar frequency of bacterial, viral ,fungal, CMV & BKV infections

41. 6% in Belatacept MI gp, N 4% in LI gp experienced corticosteroid-resistant acute rejection,N 0 in CsA Observed rates of donor-specific anti-HLA Ab production were lower in Belatacept-treated patients vs. CsA In ECD recipients renal function was better, pt/graft survival & acute rejection similar with immunosuppression regimen based on Belatacept vs. CsA No additional efficacy gained using MI regimen

45. Graft & Patient survival similar Fewer Belatacept t/t pts reached composite renal impairment endpoint vs. CsA Mean GFR 4-7ml/min higher in Belatacept gp Incidence of DGF similar Unlike BENEFIT, the incidence of acute rejection comparable across all three arms of BENEFIT-EXT, between 14% and 18% Severity of rejection higher with Belatacept Recipients of these ECD kidneys were old patients with low immunologic risk

47. Infection & malignancy rates similar CV & Metabolic outcomes superior with Belatacept More cases of PTLD in Belatacept gp (4/5 were PTLD of CNS -lethal) During first 12 mo PTLD MI(N 1) LI(N 2) and none in the CsA gp After 12 mo PTLD MI(N1) LI(1) Most cases PTLD in recipients with known risk factors

48. “Article in REVIEW”

49. Extension of the Phase II trial Comparing beyond 1 Yr Belatacept with CsA for prevention of ACUTE REJECTION & PRESERVATION OF RENAL FUNCTION Assess long term safety & efficacy of Belatacept

51. Trough concentrations of Belatacept

52. Amount of free CD86 (HA5 binding) on Monocytes from whole blood

53. 7 Belatacept receiving pts switched to Tacrolimus(5 in yr 2) 1 Belatacept receiving pt switched from MMF to Sirolimus 3 Belatacept recipients switched MMF to low dose MMF& Sirolimus Switched pts were included in final analysis Data cut off date 6yrs and 7 mo after initiation original trial At end of study all were >5Yrs post transplant (76% Belatacept & 62% CsA recipients remained in study)

54. Stable renal function in belatacept-treated patients over time Calculated GFR (MDRD) assessed at 6-mo intervals in t/t patients who reached indicated time points Data as means SD GFR decreased from 74.4 to 59.3 at mo 60 No substantial differences in GFR observed between patients on 4/8 wk dosing

55. Kaplan-Meier plot for all randomly assigned & transplant recipients in ITT population w/o cancer >60 mo Patients with skin/organ cancer/PTLD were excluded

59. Frequencies & incidence rates of SAEs occurred in 2/more pts in any group by category

60. Neoplasms in the LTE (LATE) In original study 3 cases PTLD b/w 3-13 mo after transplantation Belatacept (all in those receiving more intensive regimen)

61. Selection Bias : Self selected cohort CsA gp small allowing only limited conclusions from direct comparisons Included patients had fared well during first phase of study Both gps higher average GFR’s as compared to gps in original study Baseline characteristics (Age, Cr, Co morbidities contributing to allograft dysfunction) at study entry not published Study underpowered to detect meaningful differences especially when pts withdrew during long term follow up Study compared CsA with Tacrolimus being most widely used CNI