Rita R. Alloway

Bortezomib provides effective therapy for antibody- and cell-mediated acute rejection.

Background. Current antihumoral therapies in transplantation and autoimmune disease do not target the mature antibody-producing plasma cell. Bortezomib is a first in class proteosomal inhibitor, that is Food and Drug Administration approved, for the treatment of plasma cell-derived tumors that is multiple myeloma. We report the first clinical experience with plasma cell-targeted therapy (bortezomib) as an antirejection strategy. Methods. Eight episodes of mixed antibody-mediated rejection (AMR) and acute cellular rejection (ACR) in six transplant recipients were treated with bortezomib at labeled dosing. Monitoring included serial donor-specific antihuman leukocyte antigen antibody (DSA) levels and repeated allograft biopsies. Results. Six kidney transplant patients received bortezomib for AMR and concomitant ACR. In each case, bortezomib therapy provided (1) prompt rejection reversal, (2) marked and prolonged reductions in DSA levels, (3) improved renal allograft function, and (4) suppression of recurrent rejection for at least 5 months. Moreover, immunodominant DSA (iDSA) (i.e., the antidonor human leukocyte antigen antibody with the highest levels) levels were decreased by more than 50% within 14 days and remained substantially suppressed for up to 5 months. One or more additional DSA were present at lower concentrations (non-iDSA) in each patient and were also reduced to nondetectable levels. Bortezomib-related toxicities (gastrointestinal toxicity, thrombocytopenia, and paresthesias) were all transient. Conclusions. Bortezomib therapy: (1) provides effective treatment of AMR and ACR with minimal toxicity and (2) provides sustained reduction in iDSA and non-iDSA levels. Bortezomib represents the first effective antihumoral therapy with activity in humans that targets plasma cells.

Glomerulosclerosis as a determinant of posttransplant function of older donor renal allografts

Transplantation of kidneys from older donors is being advocated to expand the organ donor pool. However, the prevalence of atherosclerosis and age-induced renal structural alterations account for the variable function of allografts procured from these older donors. Pretransplant biopsies are sometimes used to evaluate kidneys from older donors, but to date there are no defined criteria correlating the extent of structural alterations in these kidneys to subsequent function. We investigated the effect of glomerulosclerosis, a marker for nephrosclerosis, on graft outcome. Sixty-five baseline biopsies of kidney allografts were retrospectively analyzed to identify a referent point of glomerulosclerosis that correlated with inferior graft outcome. Age and death from non-traumatic cerebrovascular injuries were the main correlates for donor glomerulosclerosis (P<0.001). Allografts with poor function at 6 months defined as serum creatinine >2.5 mg/dl (n=13) or nephrectomy (n=4) had a mean of 20% glomerulosclerosis at the time of implantation compared with only 2% sclerosis in allografts with good function (P<0.05). Delayed graft function occurred in 22% and 33% of recipients with no glomerulosclerosis and those with less than 20% glomerulosclerosis, respectively. In contrast, patients receiving kidneys with >20% sclerosis had an 87% incidence of delayed function (P<0.05). Moreover, graft loss occurred in 7% of recipients of kidneys with less than 20% sclerosis and in 38% of recipients with >20% sclerosis (P<0.04). Measurements of serum creatinine in the donors did not distinguish the different degrees of glomerulosclerosis found on biopsy. Our data indicate that donor glomerulosclerosis greater than 20% increases the risk of delayed graft function and poor outcome of transplanted kidneys. Therefore, we advocate the use of routine biopsies of kidneys from older (>50 yrs) donors and those donors with nontraumatic cerebrovascular accidents, despite seemingly normal preprocurement serum creatinine.

Reducing De Novo Donor‐Specific Antibody Levels during Acute Rejection Diminishes Renal Allograft Loss

The effect of de novo DSA detected at the time of acute cellular rejection (ACR) and the response of DSA levels to rejection therapy on renal allograft survival were analyzed. Kidney transplant patients with acute rejection underwent DSA testing at rejection diagnosis with DSA levels quantified using Luminex single‐antigen beads. Fifty‐two patients experienced acute rejection with 16 (31%) testing positive for de novo DSA. Median follow‐up was 27.0 ± 17.4 months postacute rejection. Univariate analysis of factors influencing allograft survival demonstrated significance for African American race, DGF, cytotoxic PRA >20% (current) and/or >50% (peak), de novo DSA, C4d and repeat transplantation. Multivariate analysis showed only de novo DSA (6.6‐fold increased allograft loss risk, p = 0.017) to be significant. Four‐year allograft survival was higher with ACR (without DSA) (100%) than mixed acute rejection (ACR with DSA/C4d) (65%) or antibody‐mediated rejection (35%) (p < 0.001). Patients with >50% reduction in DSA within 14 days experienced higher allograft survival (p = 0.039). De novo DSAs detected at rejection are associated with reduced allograft survival, but prompt DSA reduction was associated with improved allograft survival. DSA should be considered a potential new end point for rejection therapy.

The Effect of CYP3A5 and MDR1 Polymorphic Expression on Cyclosporine Oral Disposition in Renal Transplant Patients

Variability in CYP3A (CYP3A4/5) and P‐glycoprotein (human MDR1 gene product) activity underlies interindividual differences in oral cyclosporine (CsA) bioavailability. Racial differences in polymorphic expression of CYP3A5 and MDR1 may explain observed interracial variability in oral bioavailability. Our objective was to evaluate the effect of CYP3A5 and MDR1 polymorphic expression on CsA oral disposition. Steady‐state plasma concentration profiles (n = 19) were sampled in renal transplant recipients receiving concentration‐adjusted CsA maintenance therapy. CsA plasma concentrations were measured by fluorescence polarization immunoassay. CYP3A5 and MDR1 genotypes were determined by real‐time polymerase chain reaction. Noncompartmental pharmacokinetic analysis and nonlinear mixed‐effects modeling (NONMEM) were performed to assess the effect of genotype on CsA pharmacokinetics. MDR1 C3435T genotype was identified as the best predictor of CsA systemic exposure. CsA oral clearance was significantly higher in subjects who carried at least one 3435T allele compared to homozygous wild‐type individuals (40.0 ± 2.2 vs. 26.4 ± 3.1 L/h, p = 0.007). MDR1 C3435T genotype accounted for 43% of the interindividual variability of CsA oral clearance in the study population after accounting for interoccasion variability. The authors were unable to independently assess whether CYP3A5 correlated with any CsA pharmacokinetic parameter since all CYP3A5 nonexpressors were also 3435T allele carriers. MDR1 3435T allele carriers have enhanced oral clearance compared to individuals with the CC genotype. The frequency of the 3435T allele is lower in African Americans compared to Caucasians. Thus, the MDR1 C3435T genotype offers a potential mechanistic basis to explain interracial differences in CsA oral bioavailability. Further studies are needed to explore the relationship between CYP3A5 and MDR1 genotype and phenotype.

Proteasome Inhibitor-Based Primary Therapy for Antibody-Mediated Renal Allograft Rejection

Background. Rapid and complete elimination of donor-specific anti-human leukocyte antigen antibodies (DSA) during antibody-mediated rejection (AMR) is rarely achieved with traditional antihumoral therapies. Proteasome inhibitor-based therapy has been shown to effectively treat refractory AMR, but its use as a primary therapy for AMR has not been presented. Our initial experience with proteasome inhibition as a first-line therapy for AMR is presented. Methods. Adult kidney transplant recipients with AMR, diagnosed by Banff criteria, received a bortezomib-based regimen as the primary therapy. Bortezomib therapy was administered per package insert with plasmapheresis performed immediately before each bortezomib dose, and a single rituximab dose (375 mg/m2) given with the first bortezomib dose. DSA were quantitated using single-antigen beads on a Luminex platform. Results. Two patients underwent bortezomib-based therapy for acute AMR occurring within the first 2 weeks after transplantation. High DSA levels and positive C4d staining of peritubular or glomerular capillaries were present at the time of diagnosis. Both patients experienced prompt AMR reversal and elimination of detectable DSA within 14 days of bortezomib-based therapy. Renal function remains excellent with normal urinary protein excretion at 5 and 6 months after AMR diagnosis. One patient experienced a repeated elevation of DSA (including two new human leukocyte antigen specificities) 2 months after initial bortezomib therapy, but without C4d deposition or histologic evidence of AMR. Retreatment with bortezomib provided prompt, complete, and durable DSA elimination. Conclusions. Proteasome inhibitor-based combination therapy provides a potential means for rapid DSA elimination in early acute AMR in renal transplant recipients.

Early and Late Acute Antibody-Mediated Rejection Differ Immunologically and in Response to Proteasome Inhibition

Background. The efficacy of plasma cell targeted therapies for antibody-mediated rejection (AMR) has not been defined in detail. The purpose of this study was to compare early and late acute AMR in terms of immunologic characteristics and responses with proteasome inhibitor (PI) therapy. Methods. Renal transplant recipients with acute AMR were treated with PI-based regimens. Early acute AMR was defined as occurring within 6 months posttransplant. Immunodominant donor-specific antibody (iDSA) was defined as the DSA with the highest level. Results. Results are expressed as early or late acute AMR. Thirty AMR episodes (13 early, 17 late) were treated in 12 and 16 patients. Early but not late AMR was associated with presensitization. Late AMR iDSA levels were higher, and specificities were primarily class II (DQ being most frequent). Early AMR patients demonstrated greater reduction in iDSA at 7, 14, and 30 days and at the posttreatment nadir (81.5%+21.2% vs. 51.4%+27.6%; P<0.01). Early AMR patients were more likely to demonstrate histologic resolution/improvement (87.5% vs. 53.8%; P=0.13). Both groups demonstrated significant improvement in renal function. Conclusions. Early and late AMR exhibit distinct immunologic characteristics and respond differently to PI therapy.

De Novo Cancers Arising in Organ Transplant Recipients are Associated With Adverse Outcomes Compared With the General Population

Background. Transplant recipients are at increased risk of malignancy; however, the influence of transplantation on cancer outcomes has not been rigorously defined. The purpose of this study was to examine the influence of transplantation on the outcomes of individual cancers. Methods. De novo nonsmall cell lung cancer, colon cancer, breast cancer, prostate cancer, bladder cancer, renal cell cancer (RCC), and malignant melanoma data in 635 adult (>18 years of age) transplant recipients (from the Israel Penn International Transplant Tumor Registry) were compared with data from 1,282,984 adults in the general population (from the Surveillance, Epidemiology, and End Results database). Results. Compared with the general population, transplant patients were more likely to have early stage (AJCC stage 0–II) RCC, but more advanced (AJCC stage >II) colon cancer, breast cancer, bladder cancer, and malignant melanoma. Compared with the general population, disease-specific survival was worse in the transplant population for colon cancer (all stages), nonsmall cell lung cancer (stage II), breast cancer (stage III), prostate cancer (stage II, III, and IV), bladder cancer (stage III), and RCC (stage IV). Multivariate analyses demonstrated transplantation to be a negative risk factor for survival for each cancer studied, and transplantation and cancer stage at diagnosis to be the most profound negative survival predictors. Conclusions. These analyses indicate that, for several common cancers, transplant patients experience worse outcomes than the general population. The data also suggest that cancers in transplant recipients are more aggressive biologically at the time of diagnosis.

Pharmacokinetics of mycophenolic acid, tacrolimus and sirolimus after gastric bypass surgery in end-stage renal disease and transplant patients: a pilot study

Abstract:  Background:  Promising data regarding the safety and efficacy of gastric bypass surgery (GBS) as an option to address obesity in the transplant population are emerging. The data lack on how GBS may alter the pharmacokinetics (PK) of modern immunosuppression. The objective of this study was to describe the alterations in the PK of modern immunosuppressants and the GBS population.

Surgical complications after pancreas transplantation with portal-enteric drainage.

BACKGROUND Despite recent advances, surgical complications remain an important source of morbidity after pancreas transplantation (PTX). Several previous studies have delineated the surgical complications after PTX with systemic-bladder (S-B) drainage, but data are limited regarding the incidence and outcomes of surgical complications after PTX with portal-enteric (P-E) drainage. STUDY DESIGN We retrospectively studied surgical complications after 83 vascularized PTXs with P-E drainage in 79 patients (65 simultaneous kidney-PTXs [SKPT] and 18 solitary PTXs [SPT], 8 pancreas alone and 10 pancreas after kidney transplantation). Twelve (15%) were retransplants. A surgical complication was defined as the need for repeat laparotomy within the first 3 months after PTX. RESULTS A total of 53 surgical complications requiring repeat laparotomy occurred in 31 patients (37%). The incidence of surgical complications in SKPT and SPT was 38% and 33%, respectively. The most common indications for repeat laparotomy were: vascular thrombosis in 13% (SKPT 14% and SPT 11%), intraabdominal infection in 10% (SKPT 12% and SPT 0%), intraabdominal bleeding in 8% (SKPT 8% and SPT 11%), and duodenal allograft leak in 4% (SKPT 3% and SPT 6%). Patient survival rates at 1 and 3 years with versus without surgical complications were 84% and 80% versus 94% and 86%, respectively (p = NS). Pancreas graft survival rates at 1 and 3 years with versus without surgical complications were 48% and 44% versus 89% and 76%, respectively (p < 0.0001). The incidence of surgical complications was 45% in the first 42 P-E transplantations performed between 1990 and 1995, compared with 29% in the next 41 transplantations performed during 1996 and 1997 (p = NS). The mean number of repeat laparotomies per patient decreased from 1.2 in the former group to 0.5 in the latter group (p = NS). The incidence rates of vascular thrombosis, intraabdominal infection, and duodenal leak in the former and latter groups were 17% versus 10%, 12% versus 7%, and 2% versus 5%, respectively. CONCLUSIONS Surgical complications after PTX are common, and their incidence and outcomes with P-E drainage are similar to those with S-B drainage. The complication rate does not vary according to the type of transplant (SKPT versus SPT). Increasing experience with P-E drainage results in a decreased incidence of surgical complications.

Report of the American Society of Transplantation conference on immunosuppressive drugs and the use of generic immunosuppressants.

Considerable economic and health‐related costs are associated with the life‐long maintenance immunosuppressive therapy required to prevent transplant rejection. Generic medications have the potential of providing equivalent therapeutic efficacy at a lower economic cost. In 2001, the American Society of Transplantation invited experts to review the data and issues associated with the approval and use of generic immunosuppressants. A summary of that meeting is reported here.