Alemtuzumab (CAMPATH-1H) for the treatment of acute rejection in kidney transplant recipients: long-term follow-up.

BACKGROUND: Alemtuzumab (MabCampath, Campath-1H) is a lymphocyte-depleting monoclonal antibody increasingly used in renal transplantation. This article reports the long-term follow-up data from the first series of patients treated with alemtuzumab for biopsy-proven acute rejection (BPAR). METHODS: Fifteen patients were identified who had received alemtuzumab for BPAR between November 1991 and June 1994. Patient and allograft survival were compared with a control group consisting of 25 patients with BPAR from the same era treated with intravenous methyl prednisolone, and with a contemporaneous UK renal transplant cohort. RESULTS: All rejection episodes responded to treatment with alemtuzumab but there was an excess of early infection-associated death in this group. Long-term transplant survival was similar in both groups as was allograft function (mean creatinine concentration at 10 years was 143 micromol/L in alemtuzumab cohort and 183 micromol/L in control cohort, P=0.06). There was no excess incidence of malignancy or cytomegalovirus infection in this prolonged follow-up period.

Immunohematopoietic stem cell transplantation in Cape Town: a ten-year outcome analysis in adults.

BACKGROUND AND OBJECTIVES: Immunohematopoietic stem cell transplantation has curative potential in selected hematologic disorders. Stem cell transplantation was introduced into South Africa in 1970 as a structured experimental and clinical program. In this report, we summarize the demography and outcome by disease category, gender, and type of procedure in patients older than 18 years of age who were seen from April 1995 to December 2002. PATIENTS AND METHODS: This retrospective analysis included 247 individuals over 18 years of age for whom complete data were available. These patients received grafts mostly from peripheral blood with the appropriate stem cell population recovered by apheresis. RESULTS: Patient ages ranged from 20 to 65 years with a median age of 42 years. There were 101 females and 146 males. There were no withdrawals and 63% survived to the end of the study. At 96 months of follow-up, a stable plateau was reached for each disease category. Median survival was 3.3 years (n=6, 14.6%) for acute lymphoblastic anemia, 3.1 years (n=44, 18%) for acute myeloid leukemia, 2.8 years (n=47, 19%) for chronic granulocytic leukemia, 2.8 years (n=71, 29%) for lymphoma, 1.5 years (n=23, 9%) for myeloma, 1.43 years (n=10, 4%) for aplasia, and 1.4 years (n=38, 15%) for a miscellaneous group comprising less than 10 examples each. Multivariate analysis showed that only diagnosis and age had a significant impact on survival, but these two variables might be interrelated. There was no significant difference in outcome by source of graft. CONCLUSION: The results confirm that procedures carried out in a properly constituted and dedicated unit, which meets established criteria and strictly observes treatment protocols, generate results comparable to those in a First World referral center. Low rates of transplant-related mortality, rejection and graft-versus-host disease are confirmed, but the benefits cannot be extrapolated outside of academically oriented and supervised facilities.

Pediatric immunohematopoietic stem cell transplantation at a tertiary care center in Cape Town.

UNLABELLED: INTRODUCTION AND STUDY DESIGN: We conducted a retrospective analysis of consecutive referrals of patients under 18 years of age undergoing immunohematopoietic stem cell transplantation to assess the influence of age, diagnosis, graft type and gender on survival. We also contrasted program activity and outcome to that reported from a state hospital in the same geographical area over a comparable period. METHODS: Conditioning employed either a sequential combination of fractionated 12Gy whole body and 6Gy total nodal irradiation separated by 120mg/kg of cyclophosphamide in patients over 15 years of age. Alternatively, the latter agent was combined initially with oral busulphan and later the intravenous equivalent. Neuroblastoma cases were prepared using a different regimen. In allografts the harvested product underwent ex vivo T-cell depletion with the humanized version of anti-CD 52 monoclonal antibody designated Campath 1H. No additional immunosuppression was given except where matched unrelated volunteer donors were employed. RESULTS: Sixty-eight procedures were carried out in 61 patients over a 6-year period. Of 11 with acute myeloid leukemia, 8 are alive and well whereas 8 of the 14 with the lymphoblastic variant have died. Of the remaining 12 with hematologic malignancy, all but 2 are alive. Ten of the 17 with aplasia are alive as are all with thalassemia or sickle cell disease. None of the four variables tested affected survival. CONCLUSION: Our analysis indicates that the standardized preparative regimen, coupled with a now well-established immunosuppressive regimen, is as effective in patients under 18 years of age as in adults. Our analysis also indicates that in a resource-scarce or developing country, it is mandatory to limit high-risk and relatively expensive procedures to active teams that enjoy international accreditation, whether these be in the state or private sector.

Anti-CD45 monoclonal antibody YAML568: A promising radioimmunoconjugate for targeted therapy of acute leukemia.

UNLABELLED: The outcome of hematopoietic cell transplantation for hematologic malignancies may be improved by delivering targeted radiation to hematopoietic organs while relatively sparing nontarget organs. We evaluated the biodistribution of 111In-labeled anti-CD45 antibody in humans using the rat IgG2a monoclonal antibody YAML568 that recognizes a common CD45 epitope present on all human leukocytes. METHODS: Eight patients undergoing bone marrow transplantation received YAML568 labeled with 122 +/- 16 MBq of 111In intravenously followed by serial blood sampling, urine collection, and conjugated view planar gamma-camera imaging up to 144 h after injection. Time-activity curves were obtained using region-of-interest analysis in the accumulating organs and residence times were calculated. An estimate for the radiation-absorbed doses for each organ per unit of administered activity of 90Y was calculated using software for internal dose assessment. The first patient received no unlabeled antibody preloading. The second 2 patients received a preloading dose of 10 mg (0.15 mg/kg). The last 5 patients received a preloading dose of 30-47 mg (0.5 mg/kg). RESULTS: No significant administration-related side effects were seen. The 3 patients receiving no antibody or low antibody preloading had an unfavorable biodistribution with a high initial accumulation of activity in the liver (37%) and the spleen (34%). For the patients receiving 0.5-mg/kg antibody preloading, the estimated radiation-absorbed doses for red bone marrow, spleen, liver, kidney, and total body were 6.4 +/- 1.2, 19 +/- 5, 3.9 +/- 1.4, 1.1 +/- 0.4, and 0.6 +/- 0.1 mGy/MBq, respectively, demonstrating preferential red marrow targeting. A linear regression model showed that the amount of unlabeled antibody preloading per body weight has a strong influence on the estimated red marrow absorbed dose (P = 0.003, R2 = 0.80). CONCLUSION: This study shows that the anti-CD45 monoclonal antibody YAML568 is suitable for delivering selectively radiation to hematopoietic tissues when labeled with 90Y provided that a preloading dose of about 0.5 mg/kg unlabeled antibody is given.

Selective apoptotic killing of malignant hemopoietic cells by antibody-targeted delivery of an amphipathic peptide.

The alpha-helical amphipathic peptide D-(KLAKLAK)2 is toxic to eukaryotic cells if internalized by a suitable targeting mechanism. We have targeted this peptide to malignant hemopoietic cells via conjugation to monoclonal antibodies, which recognize lineage-specific cell surface molecules. An anti-CD19/peptide conjugate efficiently killed 3/3 B lymphoid lines. However, an anti-CD33/peptide conjugate was cytotoxic to only one of three CD33-positive myeloid leukemia lines. The IC50 towards susceptible lines were in the low nanomolar range. Conjugates were highly selective and did not kill cells that did not express the appropriate cell surface cognate of the antibody moiety. Anti-CD19/peptide conjugates efficiently killed cells from patients with chronic lymphocytic leukemia but anti-CD33/peptide reagents were less effective against fresh acute myeloid leukemia cells. We therefore suggest that amphipathic peptides may be of value as targeted therapeutic agents for the treatment of a subset of hematologic malignancies.

A comparison of the biodistribution and biokinetics of (99m)Tc-anti-CD66 mAb BW 250/183 and (99m)Tc-anti-CD45 mAb YTH 24.5 with regard to suitability for myeloablative radioimmunotherapy.

Radioimmunotherapy (RIT) with radiolabelled monoclonal antibodies (mAbs) is an effective method of achieving myeloablation in leukaemia patients prior to stem cell transplantation (SCT). We wished to compare the approaches of specific binding to leukaemic blasts and non-specific binding to benign red marrow cells, which results in a myeloablative "cross-fire" effect. Therefore, we prospectively evaluated the biodistribution and biokinetics of the anti-CD45 mAb YTH 24.5 and the anti-CD66 mAb BW 250/183 with regard to their suitability for myeloablative RIT. The red marrow selective anti-CD66 mAb BW 250/183 (IgG1) binds to normal granulopoietic cells. In contrast, the anti-CD45 mAb YTH 24.5 (IgG2b) binds to 85-90% of acute leukaemic blasts and almost all haematopoietic white cells. Patients with leukaemic blast infiltration of the marrow <25% and assigned for RIT and SCT were included. Twelve patients (eight male, four female; median age 46+/-7 years) with AML (5), CML (5) or ALL (2) were examined. Both mAbs were labelled with technetium-99m. Within 48 h, 906+/-209 MBq (99m)Tc-anti-CD66 mAb and 760+/-331 MBq (99m)Tc-anti-CD45 mAb were injected consecutively. Scintigraphic and urinary measurements were performed 1, 2, 4 and 24 h after injection. Serum activities were evaluated 2, 5, 10, 15, 30 and 60 min and 2, 4 and 24 h after injection. Compared with the anti-CD45 mAb, the anti-CD66 mAb showed an approximately fourfold higher accumulation in the red marrow, a 2.5-fold lower accumulation in the liver and similar accumulation in the kidneys. The serum activity (% of the injected dose) initially decreased faster for the anti-CD45 mAb but was similar for the two mAbs 24 h after injection: 3.3%+/-1.2% (anti-CD66 mAb) and 2.4%+/-1.1% (anti-CD45 mAb). The cumulated urinary excretion was 17%+/-6.6% (anti-CD66 mAb) and 27.3%+/-7.9% (anti-CD45 mAb) 24 h after application. In these patients with low tumour load, the anti-CD66 mAb BW 250/183 showed more favourable properties in terms of biodistribution and pharmacokinetics. Thus, it appears superior to anti-CD45 mAb YTH 24.5 in selectively increasing the marrow dose and avoiding extramedullary organ toxicity.

Immune reconstitution at 6 months following T-cell depleted hematopoietic stem cell transplantation is predictive for treatment outcome.

BACKGROUND: Compared with allogeneic bone marrow, in cytokine mobilized blood stem cell grafts, the number of hematopoietic progenitors and lymphoid cells is higher. Consequently, we compared the immune reconstitution following these two transplant modalities in patients receiving T-cell depleted grafts for hematological malignancies and studied the impact of lymphocyte subset recovery on clinical outcome. METHODS: Conditioning for transplantation was radiation-based, while graft versus host disease prophylaxis was by ex vivo T-cell depletion with Campath-1 antibodies. Clinical parameters of patients receiving bone marrow or cytokine-mobilized progenitor cell transplants were reviewed with emphasis placed on defining infectious events and on the causes of treatment failure (relapse, graft failure, or any cause of death). The blood lymphoid subsets, as well as markers for memory and naive T cells, were sequentially studied by standard flow cytometry. Serum immunoglobulins (Ig) concentrations were also determined. RESULTS: The patient population included 15 females and 27 males with a median age of 32.5 (range 15-54) years. Source of human leukocyte antigen-identical sibling allogeneic grafts was bone marrow in 14 and peripheral blood (PBPC) in 28. The median follow-up was of 1,278 (range 47-2,466) days. Following hematopoietic recovery, within the first year, 28 patients were readmitted for pyrexial episodes, and four died of sepsis. In both groups, while the CD8+ subset recuperated rapidly, CD19 and CD4+ T cells remained significantly decreased even after 12 months, leading to persistently abnormal CD4:CD8 ratios. The median values of CD16+ and CD56+ (natural killer) cells remained normal throughout the study period. Despite the patients who were receiving PBPC grafts having significantly higher numbers of allogeneic mononuclear cells (x 10(8)/kg; median: 6.97; range 4.03-10.10 vs. 0.71; range 0.45-0.99; P<0.001) and colony-forming unit granulocyte-macrophages (CFU-GMs) (x 10(4)/kg; median: 27.75; range 0-196, 2 vs. 13.05; range 2.43-57; P<0.05), the recovery rate of B cells or T-cell subpopulations was similar to those receiving bone marrow transplantation (BMT). Double fluorescence studies showed that CD2/CD45RO and RA as well as CD4/CD45RO and RA remained subnormal even after 12 months follow-up. During the observation period, except for IgA, normal levels of immunoglobulins were detected. In all, 18 out of 42 patients failed therapy, and 14 patients died. Treatment failure occurred at a median of 270 (range 47-1,638) days and was significantly associated with low total lymphocyte count (P = 0.01), CD2 (P = 0.09), CD8 (P = 0.01), CD19 (P = 0.02), CD45RA (P = 0.05), and CD4/CD45RA (P = 0.01), when tested at 6 months from transplantation. CONCLUSIONS: After T-cell depleted allogeneic PBPC or BMT, no differences in the rate of immune recovery were detected. However, patients with specific subset abnormalities at 6 months from grafting had a significantly higher risk of treatment failure.