Ngoc Thai

Opportunistic Infections in 547 Organ Transplant Recipients Receiving Alemtuzumab, a Humanized Monoclonal CD-52 Antibody

BACKGROUND Alemtuzumab is being increasingly used for the prevention and/or treatment of acute allograft rejection in organ transplant recipients. We assessed the risks of infection in, to our knowledge, the largest cohort and broadest range of organ transplant recipients yet reported to have received alemtuzumab. METHODS All patients who received alemtuzumab from September 2002 through March 2004, either as induction therapy at the time of transplantation or for the treatment of rejection, were evaluated for the development of an opportunistic infection (OI) until death or for 12 months after receipt of the last dose of alemtuzumab. RESULTS A total of 547 recipients were included, 65% of whom received alemtuzumab for induction therapy only. Overall, 56 recipients (10%) developed 62 OIs, including cytomegalovirus disease (n = 16), BK virus infection (n=12), posttransplantation lymphoproliferative disease (n=5), human herpesvirus 6 infection (n=1), parvovirus infection (n=1), esophageal candidiasis (n=12), cryptococcosis (n=2), invasive mold infection (n=4), Nocardia infection (n=4), mycobacterial infection (n=3), Balamuthia mandrillaris infection (n=1), and toxoplasmosis (n=1). Patients who received alemtuzumab for induction therapy were significantly less likely to develop an OI, compared with patients who received alemtuzumab for rejection therapy (4.5% vs. 21%; P<.001). Independent predictors of the development of an OI were administration of alemtuzumab for rejection therapy (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.8-6.8; P<.001), allograft failure (OR, 2.1; 95% CI, 1.1-4.4; P=.04), and receipt of a lung transplant (OR, 3.7; 95% CI, 1.7-8.0; P=.001) or an intestinal transplant (OR, 8.3; 95% CI, 3.5-19.5; P<.001). CONCLUSIONS Patients who received alemtuzumab for the treatment of allograft rejection were significantly more likely to develop an OI, compared with patients who received alemtuzumab for induction therapy only. Such data have implications for new antimicrobial prophylactic strategies.

Survival of liver transplant patients coinfected with HIV and HCV is adversely impacted by recurrent hepatitis C.

Although liver transplantation (LTx) in HIV‐positive patients receiving highly active antiretroviral therapy (HAART) has been successful, some have reported poorer outcomes in patients coinfected with hepatitis C virus (HCV). Here we discuss the impact of recurrent HCV on 27 HIV‐positive patients who underwent LTx. HIV infection was well controlled posttransplantation. Survival in HIV‐positive/HCV‐positive patients was shorter compared to a cohort of HIV‐negative/HCV‐positive patients matched in age, model for end‐stage liver disease (MELD) score, and time of transplant, with cumulative 1‐, 3‐ and 5‐year patient survival of 66.7%, 55.6% and 33.3% versus 75.7%, 71.6% and 71.6%, respectively, although not significantly (p = 0.07), and there was a higher likelihood of developing cirrhosis or dying from an HCV‐related complication in coinfected subjects (RR = 2.6, 95%CI, 1.06–6.35; p = 0.03). Risk factors for poor survival included African‐American race (p = 0.02), MELD score >20 (p = 0.05), HAART intolerance postLTx (p = 0.01), and postLTx HCV RNA >30 000 000 IU/mL (p = 0.00). Recurrent HCV in 18 patients was associated with eight deaths, including three from fibrosing cholestatic hepatitis. Among surviving coinfected recipients, five are alive at least 3 years after LTx, and of 15 patients treated with interferon‐α/ribavirin, six (40%) are HCV RNA negative, including four with sustained virological response. Hepatitis C is a major cause of graft loss and patient mortality in coinfected patients undergoing LTx.

Cytokine mRNA profiles in mouse orthotopic liver transplantation: Graft rejection is associated with augmented TH1 function

Although mouse liver allografts are spontaneously accepted without immunosuppression in many strain combinations, rejection can be induced by presensitization with a donor skin graft two weeks prior to transplantation. In this study, the semiquantitative reverse transcription polymerase chain reaction (RTPCR) was used to assess the involvement of T helper (TH) cell subsets in liver allograft acceptance by determining cytokine mRNA in the graft and spleen of recipients with (A) spontaneously accepting allografts (B) rejecting liver allografts after previous skin sensitization, and (C) syngeneic controls. Spontaneously accepted liver allografts showed upregulation of TH1 (IL-2, IFN-gamma) and TH2 (IL-4, IL-10) intragraft cytokine mRNA, which peaked at day 6 and tapered off thereafter, when compared with levels in syngeneic grafts, but both IFN-gamma and IL-10 mRNA persisted up to day 30. This cytokine mRNA profile correlated with the transient intragraft inflammation associated with spontaneously resolving rejection. Presensitized recipients that rejected their grafts revealed marked upregulation of TH1 (IL-2 and IFN-gamma) and TH2 (IL-4, IL-6) intragraft cytokine mRNAs compared with spontaneously accepting recipients, although IL-10 mRNA levels showed no differences between the two groups. The most striking difference was seen in IFN-gamma levels, which correlated well with the preferential deposition of IgG2a antibody isotype in the rejecting compared with the spontaneously accepting liver allograft recipients. These results suggested an association between liver allograft rejection and enhanced TH1 cytokine immune response. The ability to reject liver allografts by the adoptive transfer of splenocytes, but not serum, from a sensitized mouse ruled out preformed antibodies alone as a cause of rejection. However, spleen cytokine mRNA profiles showed no differences or trends in TH1 or TH2 expression in spontaneously accepting versus rejecting recipients, which suggested that the spleen is not a major site of alloreactive immune expansion. These data suggest that spontaneous acceptance of mouse liver allografts is associated with an insufficient intragraft TH1 cytokine response, the cause of which is currently under investigation.

Cryptococcosis in liver and kidney transplant recipients receiving anti‐thymocyte globulin or alemtuzumab

Abstract: Rabbit anti‐thymocyte globulin (ATG) and alemtuzumab have been used for induction or preconditioning and for the treatment of acute rejection in organ transplant recipients in many centers. Such regimens may lead to a substantial decline in the CD4 lymphocyte count to levels seen in other population groups at high risk of cryptococcosis. In view of this, we examined the impact of such therapy on the cumulative incidence of cryptococcosis among liver and kidney recipients. A total of 834 liver and 727 kidney transplants were performed during the study period. Seven hundred and eighty‐one patients did not receive ATG or alemtuzumab; 646 received 1 dose of either drug, and 134 patients received 2 doses of either drug. The cumulative incidence of cryptococcosis was 0.26% (2/781) among those who did not receive ATG or alemtuzumab; 0.3% (2/646) among those who received only 1 dose, and 2.24% (3/134) among those who received 2 doses (P=0.03). There were 5 cases of cryptococcosis in liver recipients and 2 in kidney recipients. There were 3 cases of cryptococcal meningitis, 3 of pneumonia, and 1 of disseminated disease. The 2 kidney recipients had meningitis. Diagnosis occurred at a median of 255 days (range 7–517) after transplantation. The mortality rate was 14.2%. We conclude that the use of 1 dose of ATG or alemtuzumab is not associated with an increased cumulative incidence of cryptococcosis, but that those patients receiving 2 doses are at increased risk.

Alemtuzumab induction and tacrolimus monotherapy in pancreas transplantation: One- and two-year outcomes.

Background. Alemtuzumab (Campath-1H) induction with tacrolimus monotherapy has been shown to provide effective immunosuppression for kidney, liver, lung, and small bowel transplantation. This drug combination was evaluated in pancreas transplant recipients. Methods. Sixty consecutive pancreas transplants (30 simultaneous pancreas-kidney, 20 pancreas after kidney, and 10 pancreas alone) were carried out under this protocol between July 2003 to January 2005. The mean follow-up was 22 months (range 17–33). Results. One-year patient, pancreas, and kidney allograft survival were 95%, 93%, and 90%, respectively. With 22 months follow-up, patient, pancreas, and kidney survival were 94%, 89%, and 87%, respectively. The rejection rate was 30% (18/60), with four patients (7%) experiencing steroid-resistant rejection. Major infection occurred in three (5%) patients resulting in two (3.3%) deaths from disseminated histoplasmosis and a herpes virus infection. One patient with cryptococcal meningitis was successfully treated. Seven (11.7%) patients experienced cytomegalovirus infection, all of whom responded to treatment with ganciclovir. One (1.7%) case of polymorphic posttransplant lymphoproliferative disease was seen, which regressed with a temporary discontinuation of tacrolimus and high-dose ganciclovir. The mean serum creatinine of the 30 simultaneous pancreas-kidney transplants at one year posttransplant was 1.37±0.33 mg/ml. The preexisting creatinine in pancreas after kidney transplants was not adversely affected by this immunosuppressive protocol. Conclusion. A single dose of perioperative alemtuzumab followed by daily tacrolimus monotherapy provides effective immunosuppression for pancreas transplantation, but the optimal use of this drug combination is not yet clear.

Evidence for early Th 2 T cell predominance in xenoreactivity.

Two distinct subsets of CD4+ Th lymphocytes have been characterized by their cytokine profiles: Th 1 (TH1) and Th 2 (TH2). While TH1 cells predominate in cell-mediated responses, TH2 cells support the humoral response. We have examined the mRNA cytokine profile of normal mouse lymphocytes in response to alloantigen versus xenoantigen (rat) in MLC, and present evidence to suggest that early in proliferative responses, alloreactivity is dominated primarily by TH1-type lymphocytes, while xenoreactivity is predominantly TH2. Normal mouse lymphocyte-responding cells were cultured in a one-way MLR with either allo or xeno antigen and examined for production of mRNA for cytokines characteristically produced by TH1 (IL-2, IFN-γ) or TH2 (IL-4, IL-10) cells. Semiquantitative reverse transcription-polymerase chain reaction analysis was performed for mouse IL-2, IL-4, IL-10, and IFN-γ mRNA. In the mouse anti-rat xeno response, mRNA for TH2 gene products were upregulated, with greater levels of IL-4 and IL-10 at 24 and 48 hr when compared with controls. In contrast, upregulation of mRNA for TH1 gene products occurred in the mouse anti-mouse allo response, with higher levels of IL-2 and IFN-γ at 24 and 48 hr. In the anti-xeno response, upregulation of all 4 cytokines occurred by day 4 and peak levels of mRNA for all cytokines examined were 2—3 times that seen for the peak anti-allogeneic response. These data suggest that early xenorecognition may differ from allorecognition by differential activation of the TH2 subset. A better understanding of the balance between Th subset function and cytokine profile in allo and xeno reactivity may allow a more targeted and specific approach to control the early events in xenograft rejection.

Alemtuzumab Preconditioning With Tacrolimus Monotherapy-The Impact of Serial Monitoring for Donor-Specific Antibody

Background. Antibody preconditioning with tacrolimus monotherapy has allowed many renal allograft recipients to be maintained on spaced weaning. Methods. Of 279 renal allograft recipients transplanted between March 2003 and December 2004, 222 (80%) had spaced weaning (i.e., reduction of tacrolimus monotherapy dosing to every other day, three times a week, twice a week, or once a week) attempted. Routine monitoring for donor-specific antibody (DSA) was begun in September 2004. Mean follow-up is 34±6.5 months after transplantation and 26±8.1 months after the initiation of spaced weaning. Results. One hundred and twenty-two (44%) patients remained on spaced weaning. One- and 2-year actual patient/graft survival was 99%/99%, and 97%/96%. Fifty-six (20%) patients experienced acute rejection after initiation of spaced weaning. One- and 2-year actual patient/graft survival was 100%/98%, and 94%/78%. Forty-two (15%) patients with stable renal function had spaced weaning stopped because of the development of DSA, which disappeared in 17 (40%). One- and 2-year actual patient and graft survival was 100% and 100%. Conclusion. Adult renal transplant recipients who are able to be maintained on spaced weaning have excellent outcomes. Patients with stable renal function who have reversal of weaning because of the development of DSA also have excellent outcomes. Routine monitoring for DSA may allow patients to avoid late rejection after spaced weaning.

Pancreas transplantation under alemtuzumab (Campath-1H) and tacrolimus: Correlation between low T-cell responses and infection

Background. Alemtuzumab induction and tacrolimus-based immunosuppression has been effective in pancreas transplantation. Despite the encouraging results of this minimalistic approach to immunosuppression, infection still remains a significant cause of morbidity. The Cylex ImmunoKnow assay was used in this study to compare pancreas recipient clinical states (stable, rejection, infection) with T cell responses. Methods. Blood samples were taken from pancreas recipients pretransplant and at approximately three-month intervals posttransplant for analysis of T cell responses. When possible, T cell responses were also quantified during changes in clinical status (infection or rejection). Results. A range between 100–300 ng/ml adenosine triphosphate (ATP) was found in stable patients (mean 194±123, n=51) with good graft function and no infection or rejection. A low T cell response was highly correlated with infectious states. The fourteen patients with infections/posttransplant lymphoproliferative disease had a mean ATP of 48 ng/ml. Risk hazard analysis showed that patients with ATP levels <100 ng/ml were four to seven times more susceptible to infection compared to stable patients. Four patients with rejection showed a T cell response of 550 ng/ml ATP, which was statistically significant compared to stable patients, although the sampling numbers (9) were too small to be conclusive. Conclusion. The Cylex ImmunoKnow assay is a valuable tool to more precisely modulate immunosuppression in pancreas transplant patients. In particular, the assay is extremely useful in detecting overly immunosuppressed patients vulnerable to infections.

Liver transplant tolerance: Mechanistic insights from animal models, with particular reference to the mouse

W ith some exceptions, organ allograft survival in humans is dependent on the prolonged use of nonspecific immunosuppressants to prevent rejection. Despite the remarkable improvements in graft survival and quality of life that have been achieved in the past 15 to 20 years because of the introduction of cyclosporine and, more recently, tacrolimus, many adverse side effects continue to be associated with the use of immunosuppressive agents, including increased risks of opportunistic infection, malignancy, and end-organ toxicities. Strenuous efforts thus continue to be made to identify methods of inducing drug-free, permanent, donor-specific unresponsiveness (tolerance), which preserve overall host immunocompetence with minimal attendant side effects. Much can to be learned from animal models. Remarkably, between some outbred pigs and in certain inbred rat and most mouse strain combinations, liver allografts are accepted across major histocompatibility barriers without the need for immunosuppressive therapy. It is not completely understood why this occurs frequently with the liver (and only exceptionally for the heart and kidney) in certain mouse strain combinations, but some insight has been gained into possible mechanisms. A fuller understanding of the mechanistic basis ofwhy livers are accepted, and why the liver induces systemic, donor-specific tolerance, is likely to have an important bearing on the design of future immunosuppressive strategies. This article focuses on recent knowledge acquired with animal models, with special reference to the mouse, in which orthotopic liver transplantation was fist accomplished successfully in 1991 .I

Proteasome inhibition with bortezomib: an effective therapy for severe antibody mediated rejection after renal transplantation.

Antibody-mediated rejection (AMR) following renal transplantation is less responsive to conventional anti-rejection therapies. Plasmapheresis (PP), intravenous immunoglobulin (IVIg), rabbit antithymocyte globulin (rATG) and rituximab deplete immature B-cells but not mature plasma cells. The proteasome inhibitor bortezomib has activity against mature plasma cell, the source of damaging donor-specific antibody (DSA).We present the successful use of bortezomib in 2 patients who developed AMR following kidney transplantation. The first patient was a 54-year-old white female who received living-unrelated kidney transplantation from her husband. She developed severe AMR early after transplantation with rising DSA titers consistent with an anamnestic immune response by memory cells to the donor antigens. Renal function deteriorated despite treatment with pulse methylprednisolone (MP), PP and IVIg. After initiation of therapy with bortezomib, DSA titers became negative and serum creatinine returned to baseline with histological resolution of AMR. The second patient was a 19-year-old white male who received deceased donor kidney transplantation and developed AMR within 2 weeks, refractory to therapy with pulse MP, PP and IVIg with rising DSA. Bortezomib use resulted in disappearance of DSA and renal function improvement. Both patients tolerated the treatment well with stable renal function at last follow-up. The novel mechanisms of action and preliminary results with bortezomib are encouraging, but require larger studies and longer follow-up.