Terminal complement inhibitor eculizumab in atypical hemolytic-uremic syndrome.

BACKGROUND: Atypical hemolytic-uremic syndrome is a genetic, life-threatening, chronic disease of complement-mediated thrombotic microangiopathy. Plasma exchange or infusion may transiently maintain normal levels of hematologic measures but does not treat the underlying systemic disease. METHODS: We conducted two prospective phase 2 trials in which patients with atypical hemolytic-uremic syndrome who were 12 years of age or older received eculizumab for 26 weeks and during long-term extension phases. Patients with low platelet counts and renal damage (in trial 1) and those with renal damage but no decrease in the platelet count of more than 25% for at least 8 weeks during plasma exchange or infusion (in trial 2) were recruited. The primary end points included a change in the platelet count (in trial 1) and thrombotic microangiopathy event-free status (no decrease in the platelet count of >25%, no plasma exchange or infusion, and no initiation of dialysis) (in trial 2). RESULTS: A total of 37 patients (17 in trial 1 and 20 in trial 2) received eculizumab for a median of 64 and 62 weeks, respectively. Eculizumab resulted in increases in the platelet count; in trial 1, the mean increase in the count from baseline to week 26 was 73×10(9) per liter (P<0.001). In trial 2, 80% of the patients had thrombotic microangiopathy event-free status. Eculizumab was associated with significant improvement in all secondary end points, with continuous, time-dependent increases in the estimated glomerular filtration rate (GFR). In trial 1, dialysis was discontinued in 4 of 5 patients. Earlier intervention with eculizumab was associated with significantly greater improvement in the estimated GFR. Eculizumab was also associated with improvement in health-related quality of life. No cumulative toxicity of therapy or serious infection-related adverse events, including meningococcal infections, were observed through the extension period. CONCLUSIONS: Eculizumab inhibited complement-mediated thrombotic microangiopathy and was associated with significant time-dependent improvement in renal function in patients with atypical hemolytic-uremic syndrome. (Funded by Alexion Pharmaceuticals; C08-002 ClinicalTrials.gov numbers, NCT00844545 [adults] and NCT00844844 [adolescents]; C08-003 ClinicalTrials.gov numbers, NCT00838513 [adults] and NCT00844428 [adolescents]).

Valaciclovir prophylaxis of cytomegalovirus infection and disease in renal transplantation: an economic evaluation.

BACKGROUND: Cytomegalovirus (CMV) disease is a major cause of morbidity and mortality in solid organ transplant patients and is associated with large additional healthcare expenditures. An economic evaluation of valaciclovir CMV prophylaxis in a renal transplant population is reported. METHODS: Medical resource use data were collected alongside a multicenter multinational randomized, placebo-controlled, double-blind trial of valaciclovir CMV prophylaxis in renal transplantation. Patients were stratified into donor seropositive/recipient sero-negative (D+R-) and recipient seropositive (R+) groups. Patients were followed-up 6 months posttransplant. A cost-effectiveness analysis from the perspective of the French health care system was performed using the number of cases of CMV disease avoided at 6 months as the clinical endpoint. RESULTS: Resource use was significantly increased among patients who developed CMV disease compared to those who did not develop disease. In the high risk D+R- group, valaciclovir prophylaxis was associated with an average of 5.5 fewer inpatient hospital days (P < OR =0.05) and with significantly lower use of other healthcare resources. In the R+ group, valaciclovir prophylaxis prevented cases of CMV disease at a marginally greater mean cost per patient compared with placebo. For D+R- patients valaciclovir prophylaxis was therefore an economically superior strategy, resulting in fewer cases of CMV disease and lower total mean healthcare expenditures. CONCLUSIONS: Valaciclovir CMV prophylaxis in renal transplantation is a more cost-effective therapy compared with placebo, in the high-risk D+R- patient population. For the R+ group, the incremental cost per case of CMV disease was modest.

Valacyclovir for the prevention of cytomegalovirus disease after renal transplantation. International Valacyclovir Cytomegalovirus Prophylaxis Transplantation Study Group.

BACKGROUND: Cytomegalovirus (CMV) disease is a major complication of organ transplantation. We hypothesized that prophylactic treatment with valacyclovir would reduce the risk of CMV disease. METHODS: A total of 208 CMV-negative recipients of a kidney from a seropositive donor and 408 CMV-positive recipients were randomly assigned to receive either 2 g of valacyclovir or placebo orally four times daily for 90 days after transplantation, with the dose adjusted according to renal function. The primary end point was laboratory-confirmed CMV disease in the first six months after transplantation. RESULTS: Treatment with valacyclovir reduced the incidence or delayed the onset of CMV disease in both the seronegative patients (P<0.001) and the seropositive patients (P=0.03). Among the seronegative patients, the incidence of CMV disease 90 days after transplantation was 45 percent among placebo recipients and 3 percent among valacyclovir recipients. Among the seropositive patients, the respective values were 6 percent and 0 percent. At six months, the incidence of CMV disease was 45 percent among seronegative recipients of placebo and 16 percent among seronegative recipients of valacyclovir; it was 6 percent among seropositive placebo recipients and 1 percent among seropositive valacyclovir recipients. At six months, the rate of biopsy-confirmed acute graft rejection in the seronegative group was 52 percent among placebo recipients and 26 percent among valacyclovir recipients (P=0.001). Treatment with valacyclovir also decreased the rates of CMV viremia and viruria, herpes simplex virus disease, and the use of inpatient medical resources. Hallucinations and confusion were more common with valacyclovir treatment, but these events were not severe or treatment-limiting. The rates of other adverse events were similar among the groups. CONCLUSIONS: Prophylactic treatment with valacyclovir is a safe and effective way to prevent CMV disease after renal transplantation.

CD4+/Leu-7+ large granular lymphocytes in long-term renal allograft recipients. A subset of atypical T cells.

In long-term renal allograft recipients on conventional immunosuppression, we have previously reported an abnormal expansion of CD3+/Leu-7+ cells. These cells are large granular lymphocytes without any natural killer activity. About 20% of these CD3+/Leu-7+ cells coexpress the CD4 differentiation antigen. In 65 transplant recipients at risk for more than 6 months, the mean percentage of peripheral blood CD4+/Leu-7+ cells is significantly increased compared with 34 normals (5.0 +/- 0.6% versus 1.0 +/- 0.1%, P less than 0.0001). Patients who never received azathioprine do not show such an abnormality. We carried out this study to further define the phenotype, morphology, and function of these cells. As to phenotype, they coexpress CD2, CD3 but do not coexpress CD1, CD8, CD11, CD16, CD19, CD25, HLA-DR, Leu-M3. Morphologically, CD4+/Leu-7+ cells are typical large granular lymphocytes undistinguishable from CD16+ effector NK cells. CD4+/Leu-7+ cells do not exhibit any natural killer cell activity. In contrast to CD4+/Leu-7- cells, CD4+/Leu-7+ cells do not proliferate when stimulated with either lectins (Con A, PHA) or allogeneic cells. When stimulated for 3 days with PHA, sorted CD4+/Leu-7+ cells do not express IL-2 receptors as detected with a PE-conjugated anti-CD25 monoclonal antibody, whereas 40% of CD4+-Leu-7- cells do so. Finally, when stimulated with PHA, CD4+-Leu-7+ cells are not able to produce detectable levels of IL-2, while CD4+-Leu-7- cells do so. In long-term renal allograft recipients on conventional immunosuppression, Leu-7 antigen identifies a subset of CD4+ cells that do not behave like regular T helper cells. We speculate that these cells represent an alteration in the cellular environment in transplant recipients, perhaps leading to long-term complications such as cancers and chronic viral infections.

Two-color flow cytometry analysis of activated T-lymphocyte subsets in type I diabetes mellitus.

We addressed the question of whether newly diagnosed type I (insulin-dependent) diabetes mellitus patients showed an increased number of DR (la+) T-lymphocytes compared with nondiabetic siblings and normal control subjects. Two-color flow cytometry measurements of peripheral-blood lymphocytes showed a slight but statistically significant increase in DR+ T-lymphocytes in diabetic subjects as well as the nondiabetic sibling control compared with the normal control subjects. This difference was not present in long-term-diabetic subjects. Thus, in addition to minor changes in this lymphocyte subset in peripheral blood, the sibling data demonstrate a lack of specificity for the disease; therefore, these measurements are probably of limited diagnostic usefulness.

Characterization of an expanded large granular lymphocyte subset lacking natural killer activity present in renal allograft recipients.

We have previously reported that, in long-term renal allograft recipients who receive chronic chemical immunosuppression and who are at risk for late chronic viral infections and virus associated tumors, the percentage of lymphocytes the phenotype of which is Leu-7+/Leu-11(-) (CD16) is markedly and significantly increased compared with that in normal controls. Since this population may lack natural killer (NK) activity and may explain the state of decreased host resistance, we carried out studies in 16 kidney transplant recipients on conventional immunosuppression and 10 age-matched normal controls to further define the phenotype, the morphology, and the NK cell activity of this particular subset. Using two-color flow cytometry analysis we found that the Leu-7+ cell subset comprises two essentially nonoverlapping subpopulations, depending on whether cells are coexpressing the NK cell marker Leu-11/CD16 (Leu-7+/Leu-11+ phenotype) or the pan-T cell marker Leu-4/CD3 (Leu-7+/Leu-4+ phenotype). We thus demonstrated that Leu-7+/Leu-11- cells do coexpress the Leu-4+/CD3 surface determinant. The percentage of Leu-7+/Leu-4+ (CD3) is significantly elevated in transplant recipients compared with that in normal controls (26 +/- 4% versus 8 +/- 2%, P less than 0.005). In contrast, the size of the Leu-7+/Leu-11+ cell subset is similar in both groups. Although in transplant recipients 70% of Leu-7+ cells coexpress Leu-4/CD3, only 43% do so in the control group. Cell sorter experiments isolated the Leu-7+/Leu-4+ cells and showed that morphologically these cells are typical large granular lymphocytes that cannot be distinguished from Leu-11+ NK cells. NK-sensitive K562 target cells showed no cytotoxicity. In contrast, Leu-7+/Leu-11+ cells exhibited high killing activity. Therefore, in long-term stable renal allograft recipients at increased risk of developing cancers and chronic viral infections, a subpopulation of non-NK large granular lymphocytes, the phenotype of which is Leu-7+/Leu-11-/Leu-4+, is abnormally expanded. This subset likely contributes to the diminished functional attributes of the chronic drug-induced immunodeficiency.

Natural killer cell subsets in long-term renal allograft recipients. A phenotypic and functional study.

Natural Killer cell subsets were studied in 39 long-term renal allotransplant recipients receiving conventional immunosuppression and 26 normal controls. Two-color flow cytometry analysis was used to determine coexpression of 2 surface antigens known to allow a phenotypic and functional discrimination of NK cells--Leu-7 a marker of large granular lymphocytes, and Leu-11c directed against the FcgammaR. In 11 patients and controls, these NK cell subsets were compared with actual NK activity assessed by killing of K562 target cells. Our data clearly show that, in long-term kidney recipients, the absolute number of NK cells (Leu-11c+) is significantly decreased compared with that of the control group. Furthermore, the most cytotoxic NK cell subset (Leu-7-/Leu-11c+ phenotype) is markedly diminished in the transplant population, whereas the less cytotoxic subset (Leu-7+/Leu-11c+) is unchanged. Finally, actual NK cell activity closely correlates with both relative and absolute numbers of these 2 NK cell subsets. These data provide convincing evidence that NK activity is impaired in long-term kidney recipients because of a diminished number of NK effector cells.

Two-color immunofluorescence and flow cytometry analysis of lymphocytes in long-term renal allotransplant recipients: identification of a major Leu-7+/Leu-3+ subpopulation.

Using two-color immunofluorescence with fluorescein isothiocyanate (FITC)- and phycoerythrin (PE)-labeled monoclonal antibodies to human lymphocyte antigens and flow cytometry, we studied lymphocyte subsets in 16 long-term renal allotransplant recipients at risk for a mean of 78 +/- 15 mo. The absolute number of Leu-1+, Leu-2a+, and Leu-3a+ lymphocytes is significantly decreased compared with a control population, whereas Leu-7+ and Leu-15+ subsets remain unchanged despite standard chronic immunosuppression (azathioprine and prednisone). Within the Leu-7+ subset, we found various phenotypes. Doubly fluorescent lymphocytes Leu-7+/Leu-1+ and Leu-7+/Leu-2a+ are not significantly different in the transplant population compared with a normal control population. The Leu-7+/Leu-3a+ subpopulation is seen to be significantly elevated, and the Leu-7+/Leu-15+ subpopulation decreases significantly. The relationship between the modification of these two phenotypes within the Leu-7 subset may be an important correlate of decreased NK cell activity in long-term renal allotransplant recipients. These Leu-7+/Leu-3a+ cells, normally less than 1% of peripheral blood lymphocytes, have no known functional activity.