Emerging role of Alemtuzumab in renal and renal–pancreas transplantation

Alemtuzumab induction and antibody-mediated rejection in kidney transplantation

BACKGROUND

Induction therapy improves graft outcomes in kidney transplant recipients (KTRs). We aimed to compare the incidences of antibody-mediated rejection (AMR) and acute cellular rejection (ACR) as well as graft and patient outcomes in KTRs who underwent induction with alemtuzumab versus rabbit-antithymocyte globulin (r-ATG).

METHODS

This was a single-center retrospective study involving patients who underwent kidney transplantation between January 2009 and December 2011 after receiving induction therapy with either alemtuzumab or r-ATG. Maintenance immunosuppression included tacrolimus and mycophenolate mofetil with early steroid withdrawal. Acute rejection was diagnosed using allograft biopsy.

RESULTS

Among the 108 study patients, 68 received alemtuzumab and 40 got r-ATG. There was a significantly higher incidence of AMR (15% vs 2.5%; P = .008) and similar incidence of ACR (4.4% vs 10%; P = .69) for alemtuzumab versus r-ATG groups. One-year serum creatinine levels (l.68 ± 0.8 mg/dL vs 1.79 ± 1.8 mg/dL; P = .66) as well as graft (91.1 ± 3.5% vs 94.5 ± 3.8%; P = .48) and patient (93.8 ± 3.0% vs 96.4 ± 3.5%; P = .92) survivals were similar for the alemtuzumab versus the r-ATG groups.

CONCLUSION

Our study showed a higher incidence of AMR and similar incidence of ACR in KTRs who underwent induction with alemtuzumab compared with those who received r-ATG and were maintained on tacrolimus and MMF. This was despite a lower HLA mismatch in the alemtuzumab group. One-year graft survival, patient survival, and allograft function were similar. Inadequate B-cell suppression by alemtuzumab as well as altered phenotypic and functional properties of repopulating B cells could be contributing to heightened risk of AMR in these patients.

B-cell tolerance in transplantation: is repertoire remodeling the answer?

T lymphocytes are the primary targets of immunotherapy in clinical transplantation; however, B lymphocytes and their secreted alloantibodies are also highly detrimental to the allograft. Therefore, the achievement of sustained organ transplant survival will likely require the induction of B-lymphocyte tolerance. During development, acquisition of B-cell tolerance to self-antigens relies on clonal deletion in the early stages of B-cell compartment ontogeny. We contend that this mechanism should be recapitulated in the setting of alloantigens and organ transplantation to eliminate the alloreactive B-cell subset from the recipient. Clinically feasible targets of B-cell-directed immunotherapy, such as CD20 and B-lymphocyte stimulator (BLyS), should drive upcoming clinical trials aimed at remodeling the recipient B-cell repertoire.

Use of the ImmuKnow assay to evaluate the effect of alemtuzumab-depleting induction therapy on cell-mediated immune function after renal transplantation

BACKGROUND

Good outcomes after renal transplantation are dependent on effective immunosuppression while minimizing infection. Alemtuzumab (Campath or Campath-1H) is an anti-CD52 humanized monoclonal IgG1 antibody which induces rapid and sustained depletion of circulating lymphocytes and has been effectively used as an immunosuppressant in post-transplant induction therapy.

METHODS

We used the ImmuKnow assay to compare cell-mediated immune function in renal transplant patients treated with alemtuzumab or with conventional immunosuppressive tri-therapy. The ImmuKnow method determines the levels of adenosine triphosphate (ATP) released from CD4 cells following stimulation with a mitogen.

RESULTS

We showed a statistically significant difference in the distribution of outcome after transplantation between the conventional and the Campath groups (P = 0.010). A significantly higher number of patients treated with alemtuzumab induction therapy were stable after transplantation compared to those treated with conventional immunosuppressive tri-therapy (96.6 vs. 75.7 %). ATP values were significantly higher in the conventional group compared to the Campath group at 180 days after transplantation (P < 0.001). ATP levels did not change significantly over time in clinically stable kidney recipients treated with alemtuzumab induction therapy (P = 0.554).

CONCLUSIONS

The ImmuKnow assay is a useful tool for evaluating the global immune response in alemtuzumab-treated renal transplant patients. Alemtuzumab-depleting induction therapy remains effective for at least 180 days.

Influence of induction modality on the outcome of deceased donor kidney transplant recipients discharged on steroid-free maintenance immunosuppression

BACKGROUND

Over last several years, alemtuzumab induction has been increasingly used in kidney transplantation especially in patients maintained on steroid-free immunosuppression. It is unclear which induction agent is associated with better graft and patient outcomes in these patients.

METHODS

Using Organ Procurement and Transplant Network/United Network of Organ Sharing database, graft and patient survivals were compared with multivariate analysis for deceased donor kidney transplant recipients from January 2000 to December 2008 who received induction with rabbit-antithymocyte globulin (r-ATG), alemtuzumab, or an interleukin-2 (IL-2) receptor blocker and were discharged on a calcineurin inhibitor/mycophenolate mofetil/steroid-free immunosuppression.

RESULTS

When compared with r-ATG (n=5348), adjusted graft survival was inferior with alemtuzumab (n=2428, hazards ratio [HR] 1.26, 95% confidence interval [CI] 1.10-1.43, P=0.001) and IL-2 receptor blocker (n=1396, HR 1.19, 95% CI 1.01-1.39, P=0.04) inductions and patient survival was inferior with alemtuzumab (HR 1.29, 95% CI 1.08-1.55, P=0.006). Alemtuzumab induction was associated with higher adjusted graft failure risks in patients with panel reactive antibody more than 20% (HR 1.30, 95% CI 1.01-1.68, P=0.04), recipients of expanded criteria donor kidneys (HR 1.58, 95% CI 1.23-2.02, P<0.001), and kidneys with cold ischemia time more than 24 hr (HR 1.31, 95% CI 1.04-1.65, P=0.02) and higher patient death risks in recipients of expanded criteria donor kidney (HR 1.66, 95% CI 1.20-1.30, P=0.002) and kidneys with cold ischemia time more than 24 hr (HR 1.44, 95% CI 1.04-2.00, P=0.03). Adjusted graft survival rates were similar for different induction agents in the low-immune risk group.

CONCLUSIONS

When compared with alemtuzumab and IL-2 receptor blocker, r-ATG induction seems to be associated with superior outcomes in deceased donor kidney transplant recipients maintained on calcineurin inhibitor/mycophenolate mofetil/steroid-free regimen.