Approval of Mycophenolate Mofetil for Prophylaxis of Organ Rejection in Pediatric Recipients of Heart or Liver Transplants: A Regulatory Perspective.

On June 6, 2022, the FDA expanded the indications for mycophenolate mofetil (MMF) to include the prophylaxis of organ rejection in combination with other immunosuppressants in pediatric recipients of allogeneic heart or liver transplants aged 3 months and older. The approved oral dosing regimen for these patients was a starting dose of 600 mg/m with titration up to a maximum of 900 mg/m twice daily. Data to support efficacy in pediatric patients were derived from established pharmacokinetic (PK) relationships across approved populations, a PK study in pediatric liver transplant recipients, and information from the Scientific Registry of Transplant Recipients database.

Summary of 2017 FDA Public Workshop: Antibody-mediated Rejection in Kidney Transplantation.

Despite major advances in understanding the pathophysiology of antibody-mediated rejection (AMR); prevention, diagnosis and treatment remain unmet medical needs. It appears that early T cell-mediated rejection, de novo donor-specific antibody (dnDSA) formation and AMR result from patient or physician initiated suboptimal immunosuppression, and represent landmarks in an ongoing process rather than separate events. On April 12 and 13, 2017, the Food and Drug Administration sponsored a public workshop on AMR in kidney transplantation to discuss new advances, importance of immunosuppressive medication nonadherence in dnDSA formation, associations between AMR, cellular rejection, changes in glomerular filtration rate, and challenges of clinical trial design for the prevention and treatment of AMR.

Absence of FcγRIII results in increased proinflammatory response in FcγRIII-KO cardiac recipients.

Background: Alloantibody can contribute significantly to rejection of heart transplants by activation of complement and interactions with a variety of effector cells, including macrophages and monocytes through activating FcγRI, FcγRIII, FcγRIV, the inhibitory FcγRIIB and complement receptors. These receptors link cellular and humoral immunity by bridging the antibody specificity to effector cells. Activating FcγRs are also involved in serum amyloid P component (SAP)-mediated clearance of apoptotic bodies.

The involvement of FcR mechanisms in antibody-mediated rejection.

Background: Antibody-mediated rejection is characterized by macrophage margination against vascular endothelium. The potential interactions triggered by antibodies between endothelial cells (EC) and macrophages have not been examined thoroughly in transplants. We used in vivo and in vitro models of antibody-mediated rejection.

B lymphocyte-directed immunotherapy promotes long-term islet allograft survival in nonhuman primates.

We found that an induction immunotherapy regimen consisting of rabbit anti-thymocyte globulin (Thymoglobulin) and the monoclonal antibody to CD20 rituximab (Rituxan) promoted long-term islet allograft survival in cynomolgus macaques maintained on rapamycin monotherapy. B lymphocyte reconstitution after rituximab-mediated depletion was characterized by a preponderance of immature and transitional cells, whose persistence was associated with long-term islet allograft survival. Development of donor-specific alloantibodies was abrogated only in the setting of continued rapamycin monotherapy.

Antibody-induced transplantation tolerance that is dependent on thymus-derived regulatory T cells.

Targeting of the CD45RB isoform by mAb (anti-CD45RB) effectively induces donor-specific tolerance to allografts. The immunological mechanisms underlying the tolerant state remain unclear although some studies have suggested the involvement of regulatory T cells (T-regs). Although their generative pathway remains undefined, tolerance promoting T-regs induced by systemic anti-CD45RB treatment have been assumed to originate in the peripheral immune system.

Expanded-criteria donor kidneys: a single-center clinical and short-term financial analysis--cause for concern in retransplantation.

Background: Expanded-criteria donor (ECD) kidneys are associated with a higher risk of posttransplant failure, but they remain a favorable alternative to dialysis. Now that a uniform definition of "expanded criteria" exists, it is more appropriate than ever to evaluate their utility compared with that seen with non-ECD kidneys.

Methods: The authors analyzed 202 cadaveric kidney-only recipients that underwent transplantation from January 1999 to September 2001, including 45 (22%) recipients whose donors met current ECD criteria.

Transplantation for type I diabetes: comparison of vascularized whole-organ pancreas with isolated pancreatic islets.

Objective: We sought to compare the efficacy, risks, and costs of whole-organ pancreas transplantation (WOP) with the costs of isolated islet transplantation (IIT) in the treatment of patients with type I diabetes mellitus.

Summary Background Data: A striking improvement has taken place in the results of IIT with regard to attaining normoglycemia and insulin independence of type I diabetic recipients. Theoretically, this minimally invasive therapy should replace WOP because its risks and expense should be less.

Factors differentially correlated with the outcome of liver transplantation in hcv+ and HCV- recipients.

Background: Survival following liver transplantation for hepatitis C virus (HCV) is significantly poorer than for liver transplants performed for other causes of chronic liver disease. The factors responsible for the inferior outcome in HCV+ recipients, and whether they differ from factors associated with survival in HCV- recipients, are unknown.

Methods: The UNOS database was analyzed to identify factors associated with outcome in HCV+ and HCV- recipients.

Early kidney dysfunction post liver transplantation predicts late chronic kidney disease.

Background: Acute and chronic renal dysfunction (ARD, CRD) are common complications after liver transplantation and are associated with poor outcome.

Methods: We reviewed the results of 181 liver transplants performed in our institution between January 1, 1998 and December 31, 2000 in which the recipients were alive with good liver function at the end of the follow-up period (mean 2.7 years).

Structural and functional abnormalities in the islets isolated from type 2 diabetic subjects.

Type 2 diabetic subjects manifest both disordered insulin action and abnormalities in their pancreatic islet cells. Whether the latter represents a primary defect or is a consequence of the former is unknown. To examine the beta-cell mass and function of islets from type 2 diabetic patients directly, we isolated islets from pancreata of type 2 diabetic cadaveric donors (n = 14) and compared them with islets from normal donors (n = 14) matched for age, BMI, and cold ischemia time.

Predicting outcome after liver transplantation: utility of the model for end-stage liver disease and a newly derived discrimination function.

Background: The Model for End-Stage Liver Disease (MELD) has been found to accurately predict pretransplant mortality and is a valuable system for ranking patients in greatest need of liver transplantation. It is unknown whether a higher MELD score also predicts decreased posttransplant survival.

Methods: We examined a cohort of patients from the United Network for Organ Sharing (UNOS) database for whom the critical pretransplant recipient values needed to calculate the MELD score were available (international normalized ratio of prothrombin time, total bilirubin, and creatinine).

Insulin independence following isolated islet transplantation and single islet infusions.

Objective: To restore islet function in patients whose labile diabetes subjected them to frequent dangerous episodes of hypoglycemic unawareness, and to determine whether multiple transplants are always required to achieve insulin independence.

Summary Background Data: The recent report by the Edmonton group documenting restoration of insulin independence by islet transplantation in seven consecutive patients with type 1 diabetes differed from previous worldwide experience of only sporadic success. In the Edmonton patients, the transplanted islet mass critical for success was approximately more than 9,000 IEq/kg of recipient body weight and required two or three separate transplants of islets isolated from two to four cadaveric donors.

The use of non-heart-beating donors for isolated pancreatic islet transplantation.

Recent improvements in isolated islet transplantation indicate that this therapy may ultimately prove applicable to patients with type I diabetes. An obstacle preventing widespread application of islet transplantation is an insufficient supply of cadaveric pancreata. Non-heart-beating donors (NHBDs) are generally not deemed suitable for whole-organ pancreas donation and could provide a significant source of pancreata for islet transplantation.

Vulnerability of allografts to rejection by MHC class II-restricted T-cell receptor transgenic mice.

Background: Examination of the in vivo activation and function of CD4+ T cells in response to allografts may advance our understanding of the rejection process. We analyzed the capacity of transgenic class II-restricted CD4 T cells to reject skin, cardiac, and islet transplants.

Methods: TS1 mice possess a high frequency of CD4+ T cells specific for the immunodominant epitope of the viral hemagglutinin (HA) protein.

Comparison of open, laparoscopic, and hand-assisted approaches to live-donor nephrectomy.

Background: Minimally invasive donor nephrectomy has become a favored procedure for the procurement of kidneys from live donors. The optimal minimally invasive surgical approach has not been determined. In the current work, we compared the outcome of kidneys procured using the traditional open approach with two minimally invasive techniques: the standard laparoscopic procedure and a hand-assist procedure.

The outcome of liver grafts procured from hepatitis C-positive donors.

Background: The growing prevalence of hepatitis C virus (HCV) infection in the general population has resulted in an increased frequency of potential organ donors that carry the virus. The survival of grafts from HCV+ donors has not been studied in detail.

Methods: Two study populations were examined retrospectively to assess the survival of liver grafts procured from HCV+ donors.