Adela Mattiazzi

Rituximab Targets Podocytes in Recurrent Focal Segmental Glomerulosclerosis

Rituximab treatment in high-risk patients with focal segmental glomerulosclerosis directly affects podocyte function and is linked to reduced incidence of recurrent proteinuria after kidney transplantation. Rituximab Prods Podocytes to Action Rituximab is a monoclonal antibody against CD20, a protein located on the surface of B cells. It is typically used to treat certain cancers and autoimmune disorders, but has also treated kidney conditions, including focal segmental glomerulosclerosis (FSGS)—a disorder that can affect both pediatric and adult patients. Recurrent FSGS is a problem for 30 to 40% of patients who have undergone kidney transplantation, and can be characterized by progression to end-stage renal disease and recurrence of proteinuria after transplant. Despite the ability of rituximab to treat FSGS, it has been unclear exactly how this drug achieves success in some patients, but not others. Fornoni and colleagues hypothesized that rituximab operates in a B cell–independent manner, targeting instead specific kidney cells called podocytes. To test this hypothesis, Fornoni et al. studied 41 patients at high risk for FSGS: 14 historical control patients who were not treated with rituximab and 27 patients who received rituximab at the time of kidney transplant. They found fewer podocytes with sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b) protein in biopsies from patients who later developed recurrent FSGS. The authors had also collected serum from all patients before transplant and then later treated normal human podocytes in culture with the sera. Serum from patients who would later develop recurrent FSGS caused a decrease in both SMPDL-3b protein and acid sphingomyelinase activity. This phenomenon was prevented by rituximab. The FSGS serum from patients also disrupted the actin cytoskeleton of cultured podocytes, but pretreatment with rituximab, or even overexpression of SMPDL-3b protein, partially prevented this phenotype. Together, these data suggest that modulation of sphingolipid-related proteins plays a role in the pathogenesis of recurrent FSGS and, moreover, that these proteins and enzymes might be targets of rituximab treatment. With the mechanism solved, rituximab may represent a new therapeutic strategy to prevent recurrent proteinuria after kidney transplantation. Here’s to happy and healthy kidneys! Focal segmental glomerulosclerosis (FSGS) is a glomerular disease characterized by proteinuria, progression to end-stage renal disease, and recurrence of proteinuria after kidney transplantation in about one-third of patients. It has been suggested that rituximab might treat recurrent FSGS through an unknown mechanism. Rituximab not only recognizes CD20 on B lymphocytes, but might also bind sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b) protein and regulate acid sphingomyelinase (ASMase) activity. We hypothesized that rituximab prevents recurrent FSGS and preserves podocyte SMPDL-3b expression. We studied 41 patients at high risk for recurrent FSGS, 27 of whom were treated with rituximab at time of kidney transplant. SMPDL-3b protein, ASMase activity, and cytoskeleton remodeling were studied in cultured normal human podocytes that had been exposed to patient sera with or without rituximab. Rituximab treatment was associated with lower incidence of posttransplant proteinuria and stabilization of glomerular filtration rate. The number of SMPDL-3b+ podocytes in postreperfusion biopsies was reduced in patients who developed recurrent FSGS. Rituximab partially prevented SMPDL-3b and ASMase down-regulation that was observed in podocytes treated with the sera of patients with recurrent FSGS. Overexpression of SMPDL-3b or treatment with rituximab was able to prevent disruption of the actin cytoskeleton and podocyte apoptosis induced by patient sera. This effect was diminished in cultured podocytes where SMPDL-3b was silenced. Our study suggests that treatment of high-risk patients with rituximab at time of kidney transplant might prevent recurrent FSGS by modulating podocyte function in an SMPDL-3b–dependent manner.

A randomized trial of three renal transplant induction antibodies: early comparison of tacrolimus, mycophenolate mofetil, and steroid dosing, and newer immune-monitoring.

Background. New trends in immunosuppression in clinical transplantation include the use of antibody induction agents in protocols that emphasize reduction or avoidance of steroids and calcineurin inhibitors. Methods. In a randomized trial using three different antibody induction agents in 90 first renal transplant recipients from cadaver donors, group A received Thymoglobulin, group B received Alemtuzumab, and group C received Daclizumab. Maintenance immunosuppression included tacrolimus and mycophenolate in all three arms, and methylprednisolone in groups A and C only (standard clinical institutional practice). The targeted trough level of tacrolimus was between 8 and 10 ng/mL for groups A and C, respectively, with a targeted mycophenolate dose of 1 g twice daily. However, in group B, the target tacrolimus trough level was 4 to 7 ng/mL to reduce long-term nephrotoxicity, with 500 mg twice-daily doses of mycophenolate, without steroid maintenance. Results. In this 15-month median postoperative interval report, there were no notable differences in demographics and patient and graft survivals. Acute rejection rates at 1 year were equivalent, that is, 5 of 30 in all three groups (16.6%). In group B, there was slightly lower renal function at 1 month, but no difference at 1 year. There was also significantly more leukopenia, but a greater percentage of T-regulatory cells and number of Fox-P3 mRNA copies by flow cytometry and semiquantitative polymerase chain reaction analysis, respectively, in group B. Conclusions. This preliminary analysis indicates that 80% of the patients in group B remained steroid-free 1 year postoperatively, with lower tacrolimus trough levels and no difference in other adverse events.

A randomized long-term trial of tacrolimus/sirolimus versus tacrolimus/mycophenolate mofetil versus cyclosporine (neoral)/sirolimus in renal transplantation. II. Survival, function, and protocol compliance at 1 year

Background. In an attempt to reduce chronic calcineurin inhibitor induced allograft nephropathy in first cadaver and human leukocyte antigen non-identical living-donor renal transplantation, sirolimus (Siro) or mycophenolate mofetil (MMF) was tested as adjunctive therapy, with planned dose reductions of tacrolimus (Tacro) over the first year postoperatively. Adjunctive Siro therapy with a similar dose reduction algorithm for Neoral (Neo) was included for comparison. Methods. The detailed dose reduction plan (Tacro and Siro, group A; Tacro and MMF, group B; Neo and Siro, group C) is described in our companion report in this issue of Transplantation. The present report documents function, patient and graft survival, protocol compliance, and adverse events. Results. As mentioned (in companion report), group demographics were similar. The present study shows no significant differences in 1-year patient and graft survival but does show a trend that points to more difficulties in group C by way of a rising slope of serum creatinine concentration (P =0.02) and decreasing creatinine clearance (P =0.04). There were more patients who discontinued the protocol plan in group C. Thus far, no posttransplant lymphomas have appeared, and infectious complications have not differed among the groups. However, a greater percentage of patients in group C were placed on antihyperlipidemia therapy, with an (unexpected) trend toward a higher incidence of posttransplant diabetes mellitus in this group. Group A required fewer, and group B the fewest, antihyperlipidemia therapeutic interventions (P <0.00001). Conclusions. This 1-year interim analysis of a long-term, prospective, randomized renal-transplant study indicates that decreasing maintenance dosage of Tacro with adjunctive Siro or MMF appears to point to improved long-term function, with reasonably few adverse events.

The Use of Campath-1h as Induction Therapy in Renal Transplantation: Preliminary Results

Background. In an attempt to reduce both initial and long-term (nephrotoxic) calcineurin inhibitor maintenance dosage and totally eliminate maintenance corticosteroids, alemtuzumab (Campath-1H) was used as induction therapy in first cadaver and non-HLA-identical living donor renal transplantation. Methods. Forty-four de novo renal allograft recipients were treated with Campath-1H (0.3 mg/kg) on days 0 and 4 postoperatively, preceded by methylprednisolone boluses. Maintenance target 12-hr tacrolimus trough levels of 5 to 7 ng/mL were operational from the outset as well as (reduced) mycophenolate mofetil dosage of 500 mg twice daily. No corticosteroids were planned to be given after the first week postoperatively. Results. With a median follow-up of 9 (range, 1–19) months, patient and graft survival rates are each at 100%. Biopsy-proven acute rejection was diagnosed in four patients. Infections requiring hospitalization developed in four patients. Thirty-eight recipients remain without the need for long-term corticosteroid therapy. Conclusions. In an early assessment, the combination of Campath-1H, low dosing of tacrolimus and mycophenolate mofetil, and avoidance of maintenance corticosteroid use seems to be safe and effective for kidney transplant recipients. Long-term outcomes will be reported in the future.

A randomized long-term trial of tacrolimus and sirolimus versus tacrolimus and mycophenolate mofetil versus cyclosporine (NEORAL) and sirolimus in renal transplantation. I. Drug interactions and rejection at one year.

Background. To reduce long-term nephrotoxic calcineurin inhibitor dosage, adjunctive sirolimus or mycophenolate mofetil (MMF) was used in a 150-patient, randomized, three-armed trial in cadaveric or human leukocyte antigen non-identical living-donor first renal transplant recipients (n=50/group). Methods. Group A received tacrolimus and sirolimus. Target tacrolimus trough levels postoperatively were 10, 8, and 6 ng/mL at 1 month, 6 months, and 1 year, respectively. Group B received tacrolimus and MMF. Target tacrolimus trough levels were 10 and 8 ng/mL at 1 month and 1 year, with a targeted dose of MMF of 1 g twice daily. Group C received cyclosporine A (CsA) (Neoral, Novartis, Basel, Switzerland) and sirolimus with target CsA trough levels of 225 and 175 ng/mL at 1 month and 1 year. Maintenance sirolimus target trough levels were 8 ng/mL in groups A and C. Each group received daclizumab induction and methylprednisolone maintenance. This first of two companion 1-year reports details demographics, drug-dosing interactions, and rejection. Results. There were no notable differences in group demographics, but a somewhat less favorable course occurred in group C, despite higher bioavailability of sirolimus in group C versus group A (P <0.001). Acute rejection rates were lower in groups A (4%) and B (4%) combined versus group C (14%) (P =0.03). Histopathologic findings were supported by comparing perioperative with 1-year postoperative protocol biopsies. Conclusions. This 1-year interim analysis indicates that a decreasing dosage of tacrolimus with either adjunctive sirolimus or MMF may optimize future graft survival versus a less favorable outcome using a similar algorithm with CsA and sirolimus.

Disparities among Blacks, Hispanics, and Whites in time from starting dialysis to kidney transplant waitlisting.

Background Although a longer time on dialysis before kidney transplant waitlisting has been shown for Blacks versus non-Blacks, relatively few studies have compared this outcome between Hispanics and Whites. Methods A multivariable analysis of 1910 (684 Black, 452 Hispanic, and 774 White) consecutive patients waitlisted at our center for a primary kidney transplant between 2005 and mid-2010 was performed for time from starting dialysis to waitlisting (months), the percentage who were preemptively waitlisted (waitlisted before starting dialysis), and time from starting dialysis to waitlisting after excluding the preemptively waitlisted patients. Results The variables associated with significantly longer median times from starting dialysis to waitlisting and less preemptive waitlisting included Medicare insurance for patients ages <65 years (by far, the most significant variable in each analysis), Black race, higher percentage of households in the patient’s zip code living in poverty, being a non-U.S. citizen (for preemptive waitlisting), Medicaid insurance, waitlisted for kidney-alone (vs. kidney-pancreas) transplant, and higher body mass index (longer median times for the latter three variables). Although the effect of Black race was mostly explained by significant associations with lower socioeconomic status (Medicare insurance for patients ages <65 years and greater poverty in the patient’s zip code), an unexplained component still remained. The univariable differences showing poorer outcomes for Hispanics versus Whites were smaller and completely explained in multivariable analysis by significant associations with lower socioeconomic status and non-U.S. citizenship. Conclusion Black and Hispanic patients had significantly longer times from starting dialysis to waitlisting, in large part related to their lower socioeconomic status and less preemptive waitlisting. A greater focus on earlier nephrology care may help to erase much of these disparities.

Graft failure due to noncompliance among 628 kidney transplant recipients with long-term follow-up: a single-center observational study.

Background In adult kidney transplantation, there is no clear consensus on the incidence of graft failure-due-to noncompliance (GFNC), with some reporting it as relatively uncommon and others as a major cause of late graft failure. We suspected that GFNC was a major cause of late graft loss at our center but did not know the extent of this problem. Methods In our prospectively followed cohort of 628 adult, primary kidney-alone transplant recipients with long-term follow-up, GFNC and other graft loss causes were determined from our ongoing clinical evaluations. Using competing risks methodology, we determined the overall percentage of patients developing GFNC and the significant prognostic factors for its hazard rate and cumulative incidence (via Cox regression). Results Cumulative incidence estimates (±standard error) of GFNC (n=29), GF-with-compliance (n=46), receiving a never-functioning graft (n=7), and death-with-a-functioning-graft (n=53) at 101 months after transplant (last-observed-graft loss) were as follows: 9.8%±2.4%, 10.9%±1.7%, 1.1%±0.4%, and 13.0%±1.9%, respectively. Only three patients experienced GFNC during the first 24 months; GFNC represented 48.1% (26/54) of death-censored GFs beyond 24 months. Two baseline variables were jointly associated with a significantly higher GFNC hazard and cumulative incidence: younger recipient age (P<0.000001 each) and non-white recipient (P=0.004 and P=0.02). Estimated percentages of ever developing GFNC were 28.4%±6.5% among 79 non-whites younger than 35 years versus 0.0% (0/144) among whites 50 years or older. Among 302 recipients younger than 50 years, 18.1%±4.1% developed GFNC, representing 67.6% (25/37) of its death-censored graft failures observed beyond 24 months after transplant. Conclusions GFNC is a major cause of late GF at our center, with younger and non-white recipients at a significantly greater GFNC risk. Interventional approaches to eliminate GFNC could dramatically improve long-term kidney graft survival.

Cytomegalovirus prophylaxis with valganciclovir in kidney, pancreas–kidney, and pancreas transplantation

Abstract:  Cytomegalovirus, seen in more than 50% of solid organ transplant recipients, is responsible for numerous direct and indirect consequences, including infection with opportunistic pathogens and allograft rejection. Prophylaxis with intravenous ganciclovir has been the gold standard for prevention; however, intravenous treatment is expensive and carries risks of its own. Oral ganciclovir, to be effective, must be given in large, divided doses. Valganciclovir, the valine ester of ganciclovir, at 900 mg/day, provides oral bioavailability equivalent to that of intravenous ganciclovir and superior to that of oral ganciclovir. This retrospective study assessed the efficacy of 3 months prophylaxis with valganciclovir in kidney, simultaneous pancreas–kidney, and pancreas transplantation. Of 161 patients, all of whom received potent immunosuppressive regimens and were followed for a mean of 440 days, only one developed cytomegalovirus infection, at 120 days post‐transplantation. Two patients died, and two others lost their grafts. There were seven incidents of acute rejection. Only seven patients discontinued treatment early, five because of leukopenia. These results suggest that prophylaxis with 900 mg/day of valganciclovir for at least 3 months safely and effectively prevents cytomegalovirus infection in kidney, simultaneous pancreas–kidney and pancreas transplant recipients on highly potent immunosuppression.

Randomized trial of three induction antibodies in kidney transplantation: long-term results.

Background In searching for an optimal induction regimen, we conducted two separate randomized trials of 38 living donor and 90 deceased donor adult, primary kidney transplant recipients comparing antithymocyte globulin (Thymoglobulin) (group A, N=43) versus alemtuzumab (group B, N=43) versus daclizumab (group C, N=42), using exactly the same three treatment arms in each trial. Methods For the purpose of maximizing statistical power, results from the two randomized trials were combined. Groups A and C received standard maintenance dosing with tacrolimus (TAC), mycophenolate mofetil (MMF), and corticosteroids. Because of intense lymphodepletion expected with alemtuzumab use (and hoped-for achievement of a truer immunoregulatory state), group B received lower TAC and MMF dosing and corticosteroid avoidance. Long-term target TAC trough level and MMF dosing were 5 to 7 ng/mL and 1,000 mg b.i.d. in groups A and C; 4 to 6 ng/mL and 500 mg b.i.d. in group B. Results With median follow-up of 95 months, biopsy-proven cute rejection incidence was similar in the three groups (8/43, 14/43, and 12/42, P=0.34), but biopsy-proven chronic allograft injury incidence was significantly higher in group B (19/43) in comparison with groups A (9/43) and C (7/42) combined (P=0.0008). Mean calculated creatinine clearance was significantly lower in group B versus the average of groups A and C means throughout 60 months posttransplant (62.9±4.2 vs. 83.6±6.9 and 79.8±5.9 at 60 months, P=0.01), and death-censored graft failure was significantly higher in group B (13/43) versus groups A (5/43) and C (5/42) combined (P=0.009). Total infection and new-onset diabetes after transplant rates were not significantly different. Ad hoc analysis suggested that the inferior results in group B were specifically a result of reduced dosing and greater withholding of TAC and MMF occurring in that group. Conclusions Long-term results clearly indicate inferior clinical outcomes in group B.

The use of daclizumab, tacrolimus and mycophenolate mofetil in African-American and Hispanic first renal transplant recipients

Limited data are available on the use of tacrolimus and mycophenolate mofetil in conjunction with anti‐IL‐2 receptor antibody, in groups of kidney transplant recipients considered to be at higher risk. This study compared the incidence of acute rejection between African‐American (AA), Hispanic (H), and non‐African‐American, non‐Hispanics (non‐AA, non‐H) first renal transplant recipients. We studied 233 sequential first renal transplants. Of the 233, 37 recipients (16%) were AA, 85 (36.5%) were H and 111 (47.5%) were non‐AA, non‐H. All received daclizumab induction therapy (1 mg/kg) on the day of surgery, and every other week for a total of 5 doses, as well as mycophenolate mofetil, tacrolimus, and steroids. At 1 year, patient and graft survival were 97% and 95% in AA, 98% and 98% in H, and 96% and 95% in non‐AA, non‐H, respectively (not statistically different). Biopsy‐proven acute rejection episodes were 8.1% in AA, 4.7% in H, and 4.5% in non‐AA, non‐H (also not statistically different). This immunosuppressive protocol appears to be safe and effective in helping to minimize biopsy‐proven acute rejection and optimize renal allograft survival in African‐American and Hispanic renal transplant recipients in the first year post transplantation.