Clonal Deletion With Bortezomib Followed by Low or No Maintenance Immunosuppression in Renal Allograft Recipients (2010)

We describe here a series of 18 patients treated with a new approach of clonal deletion. Clonal deletion differs from the usual tolerance protocols in that the protocol starts first with immunization. In contrast, tolerance protocols start first with ablation of mature cells. This trial was initiated by first giving donor-specific transfusions (DST), followed by drug treatment, designed to kill responding cells. The high graft survival with DST was reported 15 years ago (1) and again more recently (2). These results are postulated to be the result of immunization followed by clonal deletion (3). In this trial, we used bortezomib, a drug known to affect plasma cells (4, 5) and shown to reduce human leukocyte antigen (HLA) antibodies (6, 7). The clonal deletion protocol and the patient's informed consent forms were approved by the institutional review board. Selection criteria were as follows: any gender between age 10 and 65 years without infectious diseases (HIV, hepatitis B virus, hepatitis C virus, and tuberculosis), diabetes mellitus, malignancies, coronary disease, or autoimmune disorders and with a healthy donor matched for blood group. From a total of 128 patients transplanted between October 2008 and April 2009, 18 patients (89% males) met the criteria and consented to enter the study. Fifteen patients were one haplotype identical, two were two haplotype identical, and one was zero haplotype identical. They were all flow and Complement Dependent Cytoxicity (CDC) crossmatch negative. The mean patient age was 27.0±7.6 years. Eighteen patients received DST or donor peripheral blood stem cell as immunization. Three patients received one DST on pretransplant day (PTD) 14, four received two DST on PTDs 14 and 7, and all 18 received one peripheral blood stem-cell infusion on PTD 14. Thirteen patients also received a cultured donor bone marrow in the peripheral circulation plus adipose tissue-derived mesenchymal stem cells in the portal circulation on PTD 7. Bortezomib (1.3 mg/m2) was given intravenously on PTDs 13, 10, 6, and 3 along with 125 mg of methylprednisolone. Single doses of cyclophosphamide and rabbit antithymocyte globulin were given on PTD 12 at doses of 20 mg/kg body weight and 1.5 mg/kg body weight, respectively. After transplantation, single doses of rabbit antithymocyte globulin (postoperative day [POD] 0), rituximab (POD 1), and a full cycle (four doses) of bortezomib (PODs 1, 4, 8, and 11) plus methylprednisolone were given. Patients started on low-dose prednisone (5–10 mg) alone and were monitored frequently for serum creatinine and HLA antibodies. Detection of HLA antibodies was performed using LABScreen Single Antigen beads (One Lambda Inc., Canoga Park, CA). An increase of serum creatinine level to greater than 20% or increase in HLA antibodies to a level more than 1,000 normalized mean fluorescence intensity were triggers to indicate an immune event. Each immune event was treated with an increase in baseline immunosuppression, or bortezomib (if antibodies increased), or antirejection treatment (if serum creatinine increase was associated with acute rejection). As of December 8, 2009, all the 18 clonal deletion patients remain alive with a functioning allograft. The mean serum creatinine level at last follow-up is 1.51±0.4. Median follow-up is 264 days. Donor-specific antibody developed in four (22%) patients. Mean time to de novo donor-specific antibody appearance was 152 days. Acute rejection episodes occurred in four of the 18 (22%) patients, with mixed rejection in three and only one presented as a pure cellular rejection. No patients had a pure antibody-mediated rejection episode. Treatment with steroids was administered for all rejection episodes, and all resolved and returned to baseline graft function. The bortezomib-based protocol had minimal toxicity (i.e., mild nausea/diarrhea) and no grade 3 or 4 toxicity. As shown in the figure, currently, of the 18 patients, four (22%) are free of any maintenance immunosup-pression, seven (39%) are on low-dose prednisone (5–10 mg/day), and seven (39%) were treated with conventional drug maintenance immunosuppression (calcineurin inhibitor or mycophenolic acid).FIGURE 1.: Maintenance immunosuppressive profile with respect to months post transplant in the 18 patients receiving clonal deletion with bortezomib. Each patient represented by a bar, is shown with the treatment they received during the various time periods after transplantation.In summary, with a mean follow-up of 9.3 months, 11 of 18 (61%) patients treated with the clonal deletion protocol can be considered to be operationally “tolerant,” because they maintain excellent renal function (mean serum creatinine of 1.5 mg/dl) with no maintenance therapy or only with low-dose prednisone. We conclude that clonal deletion shows promise in permitting patients to be treated with a low level of immunosuppression. When low-dose prednisone was insufficient, single-agent regimens with mycophenolate mofetil or calcineurin inhibitor (in addition to low dose prednisone) were effective in maintaining function of the transplant. We propose that clonal deletion followed by the new drugs added when needed (DAWN) procedure is the pathway to the dawn of a new era in transplantation. Hargovind L. Trivedi1 Paul I. Terasaki2 Aziz Feroz1 Aruna V. Vanikar1 Varsha B. Trivedi1 Sajni I. Khemchandani1 Shruti D. Dave1 Vangipuram Shankar3 Pranjal R. Modi1 Hugo Kaneku2 Adam Idica4 Matthew J. Everly4 1 Institute of Kidney Diseases and Research Centre-Institute of Transplantation Sciences (IKDRC-ITS) Ahmedabad, Gujarat, India 2 Terasaki Foundation Laboratory Los Angeles, CA 3 M.S. Patel Cancer Centre Karamsad, Gujarat, India 4 One Lambda Inc. Canoga Park, CA