Joseph R. Leventhal

Chimerism and Tolerance Without GVHD or Engraftment Syndrome in HLA-Mismatched Combined Kidney and Hematopoietic Stem Cell Transplantation

Durable chimerism and donor-specific tolerance can be safely achieved without GVHD in HLA-mismatched donor/recipient pairs. Teaching Tolerance According to Greek mythology, the Chimera was a fire-breathing creature made of parts from different animals: the body of a lioness, a snake’s head at the end of the tail, and the head of the goat. Sightings of this fearsome beast portended any of a number of terrible disasters. In the context of organ transplantation, a “chimera” can indicate both desirable and disastrous outcomes. For example, hematopoietic chimerism, in which the immune cells in the graft recipient come from both the host and the donor, may promote graft tolerance, but may also cause graft-versus-host disease (GVHD), in which the donor immune cells attack the healthy tissue of the host. Leventhal et al. now report mixed chimerism and tolerance without the negative side effects of GVHD or engraftment syndrome in a phase 2 clinical trial of combined kidney and hematopoietic transplantation. Leventhal et al. used a combination of mobilized cells enriched for hematopoietic stem cells and graft-facilitating cells—which are composed largely of plasmacytoid precursor dendritic cells—with nonmyeloablative conditioning in conjunction with kidney transplant from major histocompatibility complex–mismatched, nonrelated donors and recipients. Five of eight kidney transplant recipients exhibited durable chimerism and were weaned off immunosuppressive therapies by 1 year after transplantation, with no signs of GVHD or engraftment syndrome. If confirmed in larger patient cohorts, this approach to transplantation could free some patients from the difficulties associated with lifelong immunosuppression and add transplantation as a viable option for patients for whom no matched donors exist. As with the Chimera of legend, mixed chimerism may be a harbinger of things to come—albeit hopefully a brighter future for transplant patients. The toxicity of chronic immunosuppressive agents required for organ transplant maintenance has prompted investigators to pursue approaches to induce immune tolerance. We developed an approach using a bioengineered mobilized cellular product enriched for hematopoietic stem cells (HSCs) and tolerogenic graft facilitating cells (FCs) combined with nonmyeloablative conditioning; this approach resulted in engraftment, durable chimerism, and tolerance induction in recipients with highly mismatched related and unrelated donors. Eight recipients of human leukocyte antigen (HLA)–mismatched kidney and FC/HSC transplants underwent conditioning with fludarabine, 200-centigray total body irradiation, and cyclophosphamide followed by posttransplant immunosuppression with tacrolimus and mycophenolate mofetil. Subjects ranged in age from 29 to 56 years. HLA match ranged from five of six loci with related donors to one of six loci with unrelated donors. The absolute neutrophil counts reached a nadir about 1 week after transplant, with recovery by 2 weeks. Multilineage chimerism at 1 month ranged from 6 to 100%. The conditioning was well tolerated, with outpatient management after postoperative day 2. Two subjects exhibited transient chimerism and were maintained on low-dose tacrolimus monotherapy. One subject developed viral sepsis 2 months after transplant and experienced renal artery thrombosis. Five subjects experienced durable chimerism, demonstrated immunocompetence and donor-specific tolerance by in vitro proliferative assays, and were successfully weaned off all immunosuppression 1 year after transplant. None of the recipients produced anti-donor antibody or exhibited engraftment syndrome or graft-versus-host disease. These results suggest that manipulation of a mobilized stem cell graft and nonmyeloablative conditioning represents a safe, practical, and reproducible means of inducing durable chimerism and donor-specific tolerance in solid organ transplant recipients.

Alemtuzumab Induction and Prednisone‐Free Maintenance Immunotherapy in Kidney Transplantation: Comparison with Basiliximab Induction—Long‐Term Results

This study examined alemtuzumab (anti‐CD 52, Campath‐1H) and basiliximab (anti‐CD 25, Simulect) as induction immunosuppression in kidney transplantation.

A prospective study of rapid corticosteroid elimination in simultaneous pancreas-kidney transplantation: comparison of two maintenance immunosuppression protocols: tacrolimus/mycophenolate mofetil versus tacrolimus/sirolimus.

Background. We examined the feasibility of rapid corticosteroid elimination in simultaneous pancreas kidney transplantation. Methods. Forty consecutive simultaneous pancreas-kidney (SPK) transplant recipients were enrolled in a prospective study in which antithymocyte globulin induction and 6 days of corticosteroids were administered along with tacrolimus and MMF (n=20) or tacrolimus and sirolimus (n=20). Mean±SD follow-up for recipients receiving tacrolimus/MMF and tacrolimus/sirolimus were 12.7±3.9 and 13.4±2.9 months, respectively. Patient and graft survival, and rejection rates were compared to an historical control group (n=86; mean follow-up 41.5±15.4 months) of SPK recipients that received induction and tacrolimus, MMF, and corticosteroids. Results. Demographic characteristics of recipient and donor variables were similar among all groups. The 1-year actuarial patient, kidney, and pancreas survival rates in the 40 SPK transplant recipients with rapid corticosteroid elimination were 100, 100, and 100%, respectively. In the historical control group the 1-year actual patient, kidney, and pancreas survival rates were 96.5, 93.0, and 91.9%, respectively. The 1-year rejection-free survival rate recipients in the rapid steroid elimination group collectively was 97.5 vs 80.2% in the historical control group (P =0.034). At 6 and 12 months posttransplant the serum creatinine values remained stable in all groups. Conclusions. We conclude that chronic corticosteroid exposure is not required in SPK transplant recipients receiving antithymocyte globulin induction and maintenance immuno-suppression consisting of either tacrolimus and mycophenolate mofetil or tacrolimus and sirolimus.

Calcineurin‐Inhibitor‐Free Immunosuppression Based on the JAK Inhibitor CP‐690,550: A Pilot Study in De Novo Kidney Allograft Recipients

This randomized, pilot study compared the Janus kinase inhibitor CP‐690,550 (15 mg BID [CP15] and 30 mg BID [CP30], n = 20 each) with tacrolimus (n = 21) in de novo kidney allograft recipients. Patients received an IL‐2 receptor antagonist, concomitant mycophenolate mofetil (MMF) and corticosteroids. CP‐690,550 doses were reduced after 6 months. Due to a high incidence of BK virus nephropathy (BKN) in CP30, MMF was discontinued in this group. The 6‐month biopsy‐proven acute rejection rates were 1 of 20, 4 of 20 and 1 of 21 for CP15, CP30 and tacrolimus groups, respectively. BKN developed in 4 of 20 patients in CP30 group. The 6‐month rates of cytomegalovirus disease were 2 of 20, 4 of 20 and none of 21 for CP15, CP30 and tacrolimus groups, respectively. Estimated glomerular filtration rate was >70 mL/min at 6 and 12 months (all groups). NK cells were reduced by ≤77% in CP‐690,550‐treated patients. In the CP‐690,550 arms, there were modest lipid elevations and a trend toward more frequent anemia and neutropenia during the first 6 months. These data suggest that coadministration of CP‐690,550 30 mg BID with MMF is associated with overimmunosuppression. At 15 mg BID, the efficacy/safety profile was comparable to the tacrolimus control group, excepting a higher rate of viral infection. Further dose‐ranging evaluation of CP‐690,550 is warranted.

Alemtuzumab Induction and Prednisone-Free Maintenance Immunotherapy in Simultaneous Pancreas-Kidney Transplantation Comparison With Rabbit Antithymocyte Globulin Induction – Long-Term Results

This study compared the effects of using two T‐cell depleting antibodies, alemtuzumab (anti‐CD 52, Campath‐1H®) and rabbit antithymocyte globulin (Thymoglobulin®), as induction immunosuppression for recipients of simultaneous pancreas‐kidney transplantation given a prednisone‐free maintenance regimen. We used a single‐center, nonrandomised, retrospective, sequential study design to evaluate the efficacy and safety of alemtuzumab (n = 50) or antithymocyte globulin (n = 38) induction in combination with a prednisone‐free, tacrolimus/sirolimus‐based immunosuppression protocol. Kaplan‐Meier analyses of long‐term patient and graft survivals and rejection rates were determined according to induction agent. Secondary endpoints included the quality of renal allograft function, incidence of infectious and malignant complications, and cost considerations. Overall long‐term patient and graft survival rates did not significantly differ between patients treated with alemtuzumab and antithymocyte globulin. Rejection rates were also nearly equivalent at 1 and 2 years. Viral infectious complications were statistically significantly lower in the alemtuzumab group. The cost of alemtuzumab induction was lower than antithymocyte globulin. Alemtuzumab induction followed by steroid‐free maintenance therapy with a tacrolimus/sirolimus‐based immunosuppression regimen provided an effective, safe and cost‐conscious approach to SPK transplantation.

Assessing Antibody Strength: Comparison of MFI, C1q, and Titer Information

The presence of donor‐specific HLA antibodies before or after transplantation may have different implications based on the antibody strength. Yet, current approaches do not provide information regarding the true antibody strength as defined by antigen–antibody dissociation rate. To assess currently available methods, we compared between neat mean fluorescence intensity (MFI) values, C1q MFI values, ethylenediaminetetraacetic acid (EDTA)‐treated samples, as well as titration studies and peak MFI values of over 7000 Luminex‐based single‐antigen HLA antibody data points. Our results indicate that neat MFI values do not always accurately depict antibody strength. We further showed that EDTA treatment (6%) does not always remove all inhibitory factors compared with C1q or titration studies. In this study of patients presenting with multiple antibody specificities, a prozone effect was observed in 71% of the cohort (usually not affecting all antibody specificities within a single serum sample, though). Similar to titration studies, the C1q assay was able to address the issue of potential inhibition; however, its limitation is its low sensitivity and inability to detect the presence of weak antibodies. Titration studies are the only method among the approaches used in this study to provide information suggesting antigen–antibody dissociation rates and are, therefore, likely to provide better indication of true antibody strength.

Laparoscopic live donor nephrectomy: Is it safe? Analysis of 80 consecutive cases and comparison with open nephrectomy

Background. Laparoscopic live donor nephrectomy (LDN) is a less invasive alternative to open nephrectomy (ODN) for living kidney donation. Concerns have been raised regarding the safety of LDN, the short and long term function of kidneys removed by LDN, and a potential higher incidence of urologic complications in LDN transplant recipients. Methods. Between October 1997 and May 1999, 80 LDNs were performed at our center. All patients were followed longitudinally with office visits and telephone interviews. These LDNs were compared with 50 ODN performed from January 1996 to October 1997. Results. LDN procedures took significantly longer than ODN (4.6 vs. 3.1 hr). However, LDN was associated with significant reduction in i.v. narcotic use, a rapid return to diet, and shorter hospital stay. Of the 80 LDN procedures, a total of 75 (94%) were completed laparoscopically. Five patients were converted to laparotomy: three for hemorrhage and two for complex vascular anatomy. ODN conversion was associated with large donor body habitus and/or obesity. Seven LDN patients had minor complications and 4 had major complications. All major complications consisted of vascular injuries (2 lumbar vein injuries, 1 renal artery, and 1 aortic injury). All patients made complete recoveries. All LDN kidneys functioned immediately posttransplant. We have observed 100% patient and 97% 1-year actuarial graft survival in LDN transplant recipients. There have been no short-or long-term urologic complications in this series. Conclusion. With increasing experience and standardization of technique, LDN is a safe and effective procedure. Patients undergoing LDN demonstrate clinically significant, more rapid postoperative recoveries and shorter hospital stays than ODN patients. Excellent initial graft function and long-term graft survival have been observed with LDN kidneys. Urologic complications can be avoided. LDN has become the preferred surgical approach for living kidney donation at our center.

Tolerance Induction in HLA Disparate Living Donor Kidney Transplantation by Donor Stem Cell Infusion: durable chimerism predicts outcome

Background We recently reported that durable chimerism can be safely established in mismatched kidney recipients through nonmyeloablative conditioning followed by infusion of a facilitating cell (FC)-based hematopoietic stem cell transplantation termed FCRx. Here we provide intermediate-term follow-up on this phase II trial. Methods Fifteen human leukocyte antigen–mismatched living donor renal transplant recipients underwent low-intensity conditioning (fludarabine, cyclophosphamide, 200 cGy TBI), received a living donor kidney transplant on day 0, then infusion of cryopreserved FCRx on day +1. Maintenance immunosuppression, consisting of tacrolimus and mycophenolate, was weaned over 1 year. Results All but one patient demonstrated peripheral blood macrochimerism after transplantation. Engraftment failure occurred in a highly sensitized (panel reactive antibody [PRA] of 52%) recipient. Chimerism was lost in three patients at 2, 3, and 6 months after transplantation. Two of these subjects had received either a reduced cell dose or incomplete conditioning; the other two had PRA greater than 20%. All demonstrated donor-specific hyporesponsiveness and were weaned from full-dose immunosuppression. Complete immunosuppression withdrawal at 1 year after transplantation was successful in all patients with durable chimerism. There has been no graft-versus-host disease or engraftment syndrome. Renal transplantation loss occurred in one patient who developed sepsis following an atypical viral infection. Two subjects with only transient chimerism demonstrated subclinical rejection on protocol biopsy despite donor-specific hyporesponsiveness. Conclusions Low-intensity conditioning plus FCRx safely achieved durable chimerism in mismatched allograft recipients. Sensitization represents an obstacle to successful induction of chimerism. Sustained T-cell chimerism is a more robust biomarker of tolerance than donor-specific hyporeactivity.

Are concerns over right laparoscopic donor nephrectomy unwarranted

ObjectiveTo examine the ability of several large, experienced transplantation centers to perform right-sided laparoscopic donor nephrectomy safely with equivalent long-term renal allograft function. Summary Background DataEarly reports noted a higher incidence of renal vein thrombosis and eventual graft loss. However, exclusion of right-sided donors would deprive a significant proportion of donors a laparoscopically harvested graft. MethodsA retrospective review was performed among 97 patients from seven centers performing right-sided laparoscopic donor nephrectomy. Surgical and postoperative demographic factors were evaluated. Complications were identified and long-term renal allograft function was compared with historical left-sided laparoscopic donor nephrectomy cohorts. ResultsRight laparoscopic donor nephrectomy was performed for varying reasons, including multiple left renal arteries or veins, smaller right kidney, or cystic right renal mass. Mean surgical time was 235.0 ± 66.7 minutes, with a mean blood loss of 139 ± 165.8 mL. Conversion was required in three patients secondary to bleeding or anatomical anomalies. Mean warm ischemic time was limited at 238 ± 112 seconds. Return to diet was achieved on average after 7.5 ± 2.3 hours, with mean discharge at 54.6 ± 22.8 hours. Two grafts were lost during the early experience of these centers to renal vein thrombosis. Both surgical and postoperative complications were limited, with few long-term adverse effects. Mean serum creatinine levels were higher than open and left laparoscopic donor nephrectomy on postoperative day 1, but at all remaining intervals the right laparoscopic donors had equivalent creatinine values. ConclusionsThese results confirm that right laparoscopic donor nephrectomy provides similar patient benefits, including early return to diet and discharge. Long-term creatinine values were no higher than in traditional open donor or left laparoscopic donor cohorts. These results establish that early concerns about high thrombosis rates are not supported by a multiinstitutional review of laparoscopic right donor nephrectomies.

Resolution of Recurrent Focal Segmental Glomerulosclerosis after Retransplantation

The authors of this letter describe the successful retransplantation of an allograft that was failing in its first recipient owing to recurrent primary focal segmental glomerulosclerosis. In the second recipient, all evidence of the nephrotic syndrome resolved.