Susan L. Saidman

HLA-Mismatched Renal Transplantation without Maintenance Immunosuppression

Five patients with end-stage renal disease received combined bone marrow and kidney transplants from HLA single-haplotype mismatched living related donors, with the use of a nonmyeloablative preparative regimen. Transient chimerism and reversible capillary leak syndrome developed in all recipients. Irreversible humoral rejection occurred in one patient. In the other four recipients, it was possible to discontinue all immunosuppressive therapy 9 to 14 months after the transplantation, and renal function has remained stable for 2.0 to 5.3 years since transplantation. The T cells from these four recipients, tested in vitro, showed donor-specific unresponsiveness and in specimens from allograft biopsies, obtained after withdrawal of immunosuppressive therapy, there were high levels of P3 (FOXP3) messenger RNA (mRNA) but not granzyme B mRNA.

Mixed lymphohaemopoietic chimerism and graft-ver suslymphoma effects after non-myeloablative therapy and HLA-mismatched bone-marrow transplantation

BACKGROUND HLA-mismatched donor bone-marrow transplantation after standard myeloablative conditioning therapy for haematological malignant disorders has been limited by severe graft-versus-host disease (GVHD) and graft failure. We tested a new approach to find out whether lymphohaemopoietic graft-versus-host reactions could occur without excessive GVHD in mixed haemopoietic chimeras produced across HLA barriers with non-myeloablative conditioning. METHODS Five patients with refractory non-Hodgkin lymphoma underwent bone-marrow transplantation from haploidentical related donors sharing at least one HLA A, B, or DR allele on the mismatched haplotype. Conditioning included cyclophosphamide and thymic irradiation before transplantation, and antithymocyte globulin before and after transplantation. The only other GVHD prophylaxis was cyclosporin. FINDINGS Four of five patients were evaluable and showed engraftment. Mixed haemopoietic chimerism was established, with a predominance of donor lymphoid tissue and varying degrees of myeloid chimerism. Two patients were in GVHD-free states of complete and partial clinical remission at 460 and 103 days after bone-marrow transplantation. INTERPRETATION Mixed chimerism can be induced in adult recipients of HLA-mismatched bone-marrow transplantation by a non-myeloablative conditioning regimen. The antilymphoma responses seen in two patients suggest that allogeneic bone-marrow transplantation without myeloablative conditioning might have potent immunotherapeutic benefits.

Combined histocompatibility leukocyte antigen-matched donor bone marrow and renal transplantation for multiple myeloma with end stage renal disease : The induction of allograft tolerance through mixed lymphohematopoietic chimerism

BACKGROUND Experimental and clinical evidence has demonstrated that the establishment of allogeneic chimerism after bone marrow transplantation may provide donor-specific tolerance for solid organ allografts. METHODS Based on the preliminary results of a clinical trial using nonmyeloablative preparative therapy for the induction of mixed lymphohematopoietic chimerism, we treated a 55-year-old woman with end stage renal disease secondary to multiple myeloma with a combined histocompatibility leukocyte antigen-matched bone marrow and renal transplant after conditioning with cyclophosphamide, antithymocyte globulin, and thymic irradiation. RESULTS The posttransplant course was notable for early normalization of renal function, the absence of acute graft-versus-host disease, and the establishment of mixed lymphohematopoietic chimerism. Cyclosporine, which was the only posttransplant immunosuppressive therapy, was tapered and discontinued on day +73 posttransplant. No rejection episodes occurred, and renal function remains normal on day + 170 posttransplant (14 weeks after discontinuing cyclosporine). Although there is presently no evidence of donor hematopoiesis, there is evidence of an ongoing antitumor response with a recent staging evaluation showing no measurable urine kappa light chains. The patient remains clinically well and is off all immunosuppressive therapy. CONCLUSION This is the first report of the deliberate induction of mixed lymphohematopoietic chimerism after a nonmyeloablative preparative regimen to treat a hematological malignancy and to provide allotolerance for a solid organ transplant.

Acute humoral rejection in renal allograft recipients: I. Incidence, serology and clinical characteristics.

Background. Acute rejection (AR) associated with de novo production of donor-specific antibodies (DSA) is a clinicopathological entity that carries a poor prognosis (acute humoral rejection, AHR). The aim of this study was to determine the incidence and clinical characteristics of AHR in renal allograft recipients, and to further analyze the antibodies involved. Methods. During a 4-year period, 232 renal transplants (Tx) were performed at our institution. Assays for DSA included T and B cell cytotoxic and/or flow cytometric cross-matches and cytotoxic antibody screens (PRA). C4d complement staining was performed on frozen biopsy tissue. Results. A total of 81 patients (35%) suffered at least one episode of AR within the first 3 months: 51 had steroid-insensitive AR whereas the remaining 30 had steroid-sensitive AR. No DSA were found in patients with steroid-sensitive AR. In contrast, circulating DSA were found in 19/51 patients (37%) with steroid-insensitive AR, and widespread C4d deposits in peritubular capillaries were present in 18 of these 19 (95%). In at least three cases, antibodies were against donor HLA class II antigens. DSA were not found in the remaining 32 patients but C4d staining was positive in 2 of 32. The DSA/C4d positive (n=18) and DSA/C4d negative (n=30) groups differed in pre-Tx PRA levels, percentage of re-Tx patients, refractoriness to antilymphocyte therapy, and outcome. Plasmapheresis and tacrolimus-mycophenolate mofetil rescue reversed rejection in 9 of 10 recipients with refractory AHR. Conclusion. More than one-third of the patients with steroid-insensitive AR had evidence of AHR, often resistant to antilymphocyte therapy. Most cases (95%) with DSA at the time of rejection had widespread C4d deposits in peritubular capillaries, suggesting a pathogenic role of the circulating alloantibody. Combined DSA testing and C4d staining provides a useful approach for the early diagnosis of AHR, a condition that often necessitates a more intensive therapeutic rescue regimen.

Intentional induction of mixed chimerism and achievement of antitumor responses after nonmyeloablative conditioning therapy and HLA-matched donor bone marrow transplantation for refractory hematologic malignancies.

Mixed lymphohematopoietic chimerism can be induced in mice with bone marrow transplantation (BMT) after a nonmyeloablative preparative regimen that includes cyclophosphamide, anti-T-cell antibody therapy, and thymic irradiation. These mixed chimeras are resistant to the induction of graft-versus-host disease (GVHD) after delayed donor leukocyte infusions (DLIs), despite a potent lymphohematopoietic graft-versus-host reaction that converts the mixed chimeric state to a full donor one. Based on this animal model, we initiated a trial of nonmyeloablative therapy with HLA-matched or -mismatched donor BMT and DLI for refractory hematologic malignancies. Twenty-one of 36 patients enrolled in this trial received a genotypically (n = 20) or phenotypically (n = 1) HLA-matched donor transplant; results reported here are for those patients only. Preparative therapy consisted of cyclophosphamide in doses of 150 to 200 mg/kg; peritransplant antithymocyte globulin; thymic irradiation (in patients who had not received previous mediastinal radiation therapy); and cyclosporine. Eighteen of 20 evaluable patients developed persistent mixed lymphohematopoietic chimerism as defined by >1% donor peripheral white blood cells until at least day 35 posttransplantation. Ten patients received prophylactic DLI beginning 5 to 6 weeks after BMT for conversion of mixed chimerism to full donor hematopoiesis and to optimize a graft-versus-leukemia effect. Fourteen of 20 evaluable patients (70%) achieved an antitumor response; 8 of these responses were complete, and 6 were partial. Of the 8 evaluable patients who received prophylactic DLI, 6 showed conversion to full donor chimerism. Five of the 9 evaluable patients (56%) who received prophylactic DLI achieved a complete response, compared with 3 of 11 patients (27%) who did not receive prophylactic DLI. Currently 11 patients are alive, and 7 of these are free of disease progression at a median follow-up time of 445 days (range, 105-548 days) posttransplantation. Transplantation-related complications included cyclophosphamide-induced cardiac toxicity in 3 of 21 patients (14%) and grade II or greater GVHD in 6 patients (29%). One patient (5%) died from a complication of BMT, and 1 patient (5%) died from GVHD after 2 prophylactic DLIs were given for conversion of chimerism. In summary, mixed lymphohematopoietic chimerism was reproducibly induced after a novel nonmyeloablative preparative regimen incorporating chemotherapy, peritransplant antithymocyte globulin, and thymic irradiation, allowing for early administration of DLI in 10 of 21 patients. After treatment, striking antitumor responses were observed in the majority of patients with chemotherapy-refractory hematologic malignancies.

Myeloma Responses and Tolerance Following Combined Kidney and Nonmyeloablative Marrow Transplantation: In Vivo and In Vitro Analyses

Six patients with renal failure due to multiple myeloma (MM) received simultaneous kidney and bone marrow transplantation (BMT) from HLA‐identical sibling donors following nonmyeloablative conditioning, including cyclophosphamide (CP), peritransplant antithymocyte globulin and thymic irradiation. Cyclosporine (CyA) was given for approximately 2 months posttransplant, followed by donor leukocyte infusions. All six patients accepted their kidney grafts long‐term. Three patients lost detectable chimerism but accepted their kidney grafts off immunosuppression for 1.3 to >7 years. One such patient had strong antidonor cytotoxic T lymphocyte (CTL) responses in association with marrow rejection. Two patients achieved full donor chimerism, but resumed immunosuppression to treat graft‐versus‐host disease. Only one patient experienced rejection following CyA withdrawal. He responded to immunosuppression, which was later successfully withdrawn. The rejection episode was associated with antidonor Th reactivity. Patients showed CTL unresponsiveness to cultured donor renal tubular epithelial cells. Initially recovering T cells were memory cells and were enriched for CD4+CD25+ cells. Three patients are in sustained complete remissions of MM, despite loss of chimerism in two. Combined kidney/BMT with nonmyeloablative conditioning can achieve renal allograft tolerance and excellent myeloma responses, even in the presence of donor marrow rejection and antidonor alloresponses in vitro.

Plasma exchange and tacrolimus-mycophenolate rescue for acute humoral rejection in kidney transplantation

BACKGROUND Acute renal allograft rejection associated with the development of donor-specific alloantibody (acute humoral rejection, AHR) typically carries a poor prognosis. The best treatment of this condition remains undefined. METHODS During a 14-month period, 73 renal transplants were performed. During the first postoperative month, five recipients (6.8%) with AHR were identified. The diagnosis was based on: (1) evidence of severe rejection, resistant to steroid and antilymphocyte therapy; (2) typical pathologic features; and (3) demonstration of donor-specific alloantibody (DSA) in recipients serum at the time of rejection. Pretransplant donor-specific T- and B-cell cross-matches were negative. RESULTS Plasma exchange (PE, four to seven treatments per patient) significantly decreased circulating DSA to almost pretransplant levels in four of five patients, and improvement in renal function occurred in all patients. One patient had recurrent renal dysfunction in the setting of an increase in circulating DSA. A second series of five PE treatments decreased DSA and reversed the rejection episode. Rescue therapy with tacrolimus (initial mean dose: 0.14+/-0.32 mg/kg/day) and mycophenolate mofetil (2 g/day) was used in five of five and four of five patients, respectively. With a mean follow-up of 19.6+/-5.6 months, patient and allograft survival are 100%. Renal function remains excellent with a mean current serum creatinine of 1.2+/-0.3 mg/dl. (range: 0.9-1.8 mg/dl). CONCLUSIONS Our findings suggest that a therapeutic approach combining PE and tacrolimus-mycophenolate mofetil rescue has the potential to improve the outcome of AHR.

Long-Term Results in Recipients of Combined HLA-Mismatched Kidney and Bone Marrow Transplantation Without Maintenance Immunosuppression

We report here the long‐term results of HLA‐mismatched kidney transplantation without maintenance immunosuppression (IS) in 10 subjects following combined kidney and bone marrow transplantation. All subjects were treated with nonmyeloablative conditioning and an 8‐ to 14‐month course of calcineurin inhibitor with or without rituximab. All 10 subjects developed transient chimerism, and in seven of these, IS was successfully discontinued for 4 or more years. Currently, four subjects remain IS free for periods of 4.5–11.4 years, while three required reinstitution of IS after 5–8 years due to recurrence of original disease or chronic antibody‐mediated rejection. Of the 10 renal allografts, three failed due to thrombotic microangiopathy or rejection. When compared with 21 immunologically similar living donor kidney recipients treated with conventional IS, the long‐term IS‐free survivors developed significantly fewer posttransplant complications. Although most recipients treated with none or two doses of rituximab developed donor‐specific antibody (DSA), no DSA was detected in recipients treated with four doses of rituximab. Although further revisions of the current conditioning regimen are planned in order to improve consistency of the results, this study shows that long‐term stable kidney allograft survival without maintenance IS can be achieved following transient mixed chimerism induction.

Graft-Versus-Tumor Induction With Donor Leukocyte Infusions as Primary Therapy for Patients With Malignancies

PURPOSE Histocompatible allogeneic donor leukocyte infusions (DLIs) were administered as primary cancer therapy in a phase I trial to determine (1) whether mixed chimerism could be detected without a prior allogeneic transplantation, (2) the toxicity of primary DLI, and (3) whether a graft-versus-tumor (GVT) reaction could be observed. PATIENTS AND METHODS Eighteen patients were studied. Patients received interferon alfa-2b for a minimum of 4 weeks, followed by DLI (level 1). Patients with no toxicity or engraftment were eligible to receive cytarabine or cyclophosphamide followed by another course of DLI (level 2). Engraftment was determined using polymerase chain reaction amplification of donor and host-specific DNA polymorphisms. RESULTS Donor cells were detected in the blood in 14 of 16 assessable patients within 1 hour of DLI. Chimerism detectable 4 weeks after DLI was observed in four patients, and five patients were not assessable. Prior autologous transplantation was associated with late chimerism (P =.0014). Acute graft-versus-host disease (GVHD) occurred in four of 16 assessable patients (grade 1, two patients; grade 2, one patient; grade 4, one patient). One patient with grade 4 acute GVHD developed pancytopenia. Only the four patients treated after prior autologous transplantation developed acute GVHD (P =.0005). Three of four patients with acute GVHD and late chimerism responded to primary DLI, and one patient was not assessable for response. CONCLUSION Allogeneic adoptive immunotherapy resulted in sustained chimerism, acute GVHD, and a GVT response in heavily pretreated patients. This indicates that it may be possible to generate a direct GVT response for patients with malignancies without the need for intensive conditioning therapy immediately before DLI. Immunosuppression may be required for sustained donor cell engraftment.

Impact of prophylactic donor leukocyte infusions on mixed chimerism, graft-versus-host disease, and antitumor response in patients with advanced hematologic malignancies treated with nonmyeloablative conditioning and allogeneic bone marrow transplantation

In an attempt to capture graft-versus-tumor effects without graft-versus-host disease (GVHD), the authors initiated a trial of nonmyeloablative allogeneic bone marrow transplantation (BMT) in patients with advanced hematologic malignancies, with the majority of patients having chemotherapy-refractory disease. Forty-two patients received an HLA-matched related donor BMT after a cyclophosphamide and antithymocyte globulin-based conditioning that also included thymic irradiation for patients who had not received prior mediastinal radiotherapy. Prophylactic donor leukocyte infusion (pDLI) at a dose of 1 x 10(7) CD3(+) cells per kilogram were given beginning 5 weeks post-BMT to 16 patients with mixed chimerism (MC) but without GVHD, whereas 26 patients did not receive pDLI, either because of GVHD or early relapse. Twelve of 16 patients (75%) receiving pDLI had T cell chimerism at the time of pDLI >/=40%. These patients, by day 100 post-BMT, either converted to full donor chimerism (FDC) (n = 10) or had an increase in or stable donor chimerism (n = 2) after pDLI. Four of 4 patients whose T cell chimerism was </=20% at the time of pDLI, lost the graft. In contrast, only 5 of 18 evaluable patients (28%) not receiving a pDLI converted to FDC by day 100 post-BMT, 7 maintained MC, and 10 of an evaluable 22 lost the graft. Patients who had undergone a previous autologous stem cell transplant had a higher rate of conversion to FDC (69% v 31%) and higher incidence of GVHD (69% v 34%) compared with those who did not have a previous autologous SCT. Eleven of 16 patients (69%) who received a pDLI achieved a remission with 50% 1-year progression-free survival rate and 44% 3-year overall survival rate. Nineteen of 42 patients (45%) had >/=grade II acute GVHD, including 12 after BMT and 7 after pDLI. Approximately one third of patients, after having initial MC, eventually lost their donor graft. The authors conclude that (1) pDLI has the potential to convert MC to FDC; (2) sustained remissions can be achieved in patients with chemorefractory hematologic malignancies who receive a pDLI, albeit with a significant risk of acute GVHD; and (3) the degree of donor T cell chimerism at the time of pDLI is predictive of the fate of MC, ie, donor T cell chimerism >/=40% or </=20% at the time of pDLI correlates with conversion of MC or loss of the graft, respectively.