Pegloticase efficacy and safety in kidney transplant recipients; results of the phase IV, open-label PROTECT clinical trial.

INTRODUCTION: Kidney transplant (KT) recipients have a high prevalence and severity of gout. Pegloticase (pegylated recombinant uricase) rapidly metabolizes serum uric acid (sUA), and its efficacy is not impacted by kidney function. METHODS: This open-label, Phase 4 trial (PROTECT NCT04087720) examined safety and efficacy of pegloticase in 20 participants with KT > 1 year prior to enrollment and with uncontrolled gout (sUA ≥7 mg/dL, intolerance/inefficacy to urate lowering therapy, and ≥1 of the following: tophi, chronic gouty arthritis, ≥2 flares in past year) and functioning KT (estimated glomerular filtration rate [eGFR] ≥15 mL/min/1.73 m2 ) on stable immunosuppression therapy. RESULTS: The primary endpoint was sUA response during month 6 (sUA < 6 mg/dL for ≥80% of time). The study enrolled 20 participants (mean ± SD); age: 53.9 ± 10.9 years, time since KT: 14.7 ± 6.9 years, sUA: 9.4 ± 1.5 mg/dL, gout duration: 8.4 ± 11.6 years; all on ≥2 stable doses of immunosuppression agents. Pegloticase (8 mg intravenous every 2 weeks) in KT recipients with uncontrolled gout showed a high response rate of 89% (16/18 responders). Two participants discontinued treatment solely due to COVID-19 concerns prior to month 6 were not included in the primary analysis. Pegloticase exposures were higher than those historically observed with pegloticase monotherapy, and no anaphylaxis or infusion reaction events occurred during the study. CONCLUSIONS: This improved response rate to pegloticase in the KT population reflects observations from other trials and reports on immunomodulation with pegloticase. As the KT population has a high prevalence of gout and limitations with oral urate lowering medication options, these findings suggest a potential option for uncontrolled gout therapy in KT participants.

SARS-CoV-2 Neutralizing Monoclonal Antibodies for the Treatment of COVID-19 in Kidney Transplant Recipients.

Background: Morbidity and mortality associated with coronavirus disease 2019 (COVID-19) infection in kidney transplant recipients are high and early outpatient interventions to prevent progression to severe disease are needed. SARS-CoV-2 neutralizing mAbs, including bamlanivimab and casirivimab-imdevimab, received emergency use authorization in the United States in November 2020 for treatment of mild to moderate COVID-19 disease. Methods: We performed a retrospective analysis of 27 kidney transplant recipients diagnosed with COVID-19 between July 2020 and February 2021 who were treated with bamlanivimab or casirivimab-imdevimab and immunosuppression reduction. We additionally identified 13 kidney transplant recipients with COVID-19 who had mild to moderate disease at presentation, who did not receive mAbs, and had SARS-CoV-2 serology testing available. Results: There were no deaths or graft failures in either group. Both infusions were well tolerated. Four of the 27 patients treated with mAbs required hospitalization due to COVID-19. Four of 13 patients who did not receive mAbs required hospitalization due to COVID-19. Patients who received mAbs demonstrated measurable anti-SARS-CoV-2 IgG with angiotensin-converting enzyme 2 (ACE2) receptor blocking activity at the highest level detectable at 90 days postinfusion, whereas ACE2 blocking activity acquired from natural immunity in the mAb-untreated group was weak. Conclusions: Bamlanivimab and casirivimab-imdevimab combined with immunosuppression reduction were well tolerated and associated with favorable clinical outcomes in kidney transplant recipients diagnosed with mild to moderate COVID-19.

Successful Induction of Specific Immunological Tolerance by Combined Kidney and Hematopoietic Stem Cell Transplantation in HLA-Identical Siblings

Induction of immunological tolerance has been the holy grail of transplantation immunology for decades. The only successful approach to achieve it in patients has been a combined kidney and hematopoietic stem cell transplantation from an HLA-matched or -mismatched living donor. Here, we report the first three patients in Europe included in a clinical trial aiming at the induction of tolerance by mixed lymphohematopoietic chimerism after kidney transplantation. Two female and one male patient were transplanted with a kidney and peripherally mobilized hematopoietic stem cells from their HLA-identical sibling donor. The protocol followed previous studies at Stanford University: kidney transplantation was performed on day 0 including induction with anti-thymocyte globulin followed by conditioning with 10x 1.2 Gy total lymphoid irradiation and the transfusion of CD34+ cells together with a body weight-adjusted dose of donor T cells on day 11. Immunosuppression consisted of cyclosporine A and steroids for 10 days, cyclosporine A and mycophenolate mofetil for 1 month, and then cyclosporine A monotherapy with tapering over 9–20 months. The 3 patients have been off immunosuppression for 4 years, 19 months and 8 months, respectively. No rejection or graft-versus-host disease occurred. Hematological donor chimerism was stable in the first, but slowly declining in the other two patients. A molecular microscope analysis in patient 2 revealed the genetic profile of a normal kidney. No relevant infections were observed, and the quality of life in all three patients is excellent. During the SARS-CoV-2 pandemic, all three patients were vaccinated with the mRNA vaccine BNT162b2 (Comirnaty®), and they showed excellent humoral and in 2 out 3 patients also cellular SARS-CoV-2-specific immunity. Thus, combined kidney and hematopoietic stem cell transplantation is a feasible and successful approach to induce specific immunological tolerance in the setting of HLA-matched sibling living kidney donation while maintaining immune responsiveness to an mRNA vaccine (ClinicalTrials.gov: NCT00365846).