Valda Thomas

CD52 antibodies for prevention of graft-versus-host disease and graft rejection following transplantation of allogeneic peripheral blood stem cells

Graft-versus-host disease (GVHD) is a major cause of mortality and morbidity after allogeneic bone marrow transplantation, but can be avoided by removing T lymphocytes from the donor bone marrow. However, T cell depletion increases the risk of graft rejection. In this study, two strategies are used to overcome rejection: (1) use of high doses of stem cells obtained from peripheral blood (PBSC), (2) admixture with a CD52 monoclonal antibody in order to deplete both donor and residual recipient lymphocytes. Two antibodies are compared: CAMPATH-1G (rat IgG2b) and its humanized equivalent CAMPATH-1H (human IgG1). A total of 187 consecutive patients at six centers received PBSC transplants from HLA-matched siblings between 1997 and 1999. A wide spectrum of diseases, both malignant and non-malignant, was included. The recovery of CD34+ cells after antibody treatment was close to 100%. The risk of acute GVHD (grade 2 to 4) was 11% in the CAMPATH-1G group and 4% in the CAMPATH-1H group (P = NS). The risk of chronic GVHD (any grade) was 11% in the CAMPATH-1G group and 24% in the CAMPATH-1H group (P = 0.03) but the risk of extensive chronic GVHD was only 2%. The overall risk of graft failure/rejection was 2%, not significantly different between the two antibodies. Antibody treatment was equally effective at concentrations between 10 μg/ml and 120 μg/ml and it made no significant difference to the outcome whether the patients received post-transplant immunosuppression or not (87% did not). Transplant-related mortality in this heterogenous group of patients (including high-risk and advanced disease) was 22% at 12 months. It is proposed that treatment of peripheral blood stem cells with CAMPATH-1H is a simple and effective method for depleting T cells which may be applicable to both autologous and allogeneic transplants from related or unrelated donors. Special advantages of this approach are the simultaneous depletion of donor B cells (which reduces the risk of EBV-associated lymphoproliferative disease) and the concomitant infusion of CAMPATH-1H to deplete residual recipient T cells and thus prevent graft rejection. Bone Marrow Transplantation (2000) 26, 69–76.

Immune reconstitution after allogeneic bone marrow transplantation depleted of T cells.

BACKGROUND Immune reconstitution following transplantation in individuals who had received T-cell-depleted marrow from HLA identical siblings was serially documented and correlated with the clinical recovery. METHODS Patients were preconditioned with radiation containing programs. GvHD prophylaxis was by T-cell depletion with CAMPATH 1G (ex vivo; median dose 20 mg). After transplantation lymphoid development was studied by flow cytometry and serum Ig concentrations were determined. Charts were reviewed to determine the effects of the immune reconstitution on the clinical performance. RESULTS The mean donor mononuclear cell number infused was 0.89x10(8)/kg. Within 6 months all the patients recovered their blood parameters and only one required therapy for GvHD. However, despite normal blood counts, 15 suffered life-threatening opportunistic infections, developing at a median of 24 weeks post grafting, but occurring even after 11 months. At 8 weeks from marrow infusion when leukocyte values had normalized in 15/20, compared to normal, immunophenotyping of blood cells from BMT revealed a significantly reduced mean lymphocyte count (1.06, SD 0.83x10(9)/l; P = 0.01), cells expressing CD3 (0.7x10(9)/l, SD 0.68; P = 0.05), CD4 (0.13x10(9)/l, SD 0.21; P = 0.0001) and CD19 (0.04x10(9)/l, SD 0.05; P = 0.001). Populations expressing CD8 and CD56 remained within normal range throughout the study. Normalization of cell numbers displaying CD2, CD3 and CD19 was delayed until 52, 52 and 24 weeks respectively, while CD4 counts persisted subnormal even at 72 weeks. Serum IgA levels were significantly decreased for the entire study period. CONCLUSIONS T-cell depletion with CAMPATH 1G while effectively preventing GvHD, also causes clinically significant and prolonged immunosuppression with apparently important clinical implications.

Ex vivo depletion of T cells from bone marrow grafts with CAMPATH-1 in acute leukemia : Graft-versus-host disease and graft-versus-leukemia effect

BACKGROUND Preventing graft-versus-host disease (GVHD) by depletion of T lymphocytes from the stem cell graft for transplantation remains controversial, mainly because of the perceived increase in disease recurrence. METHODS We retrospectively analyzed the outcome of 50 consecutive individuals in remission of acute lymphoblastic leukemia (n=13; 8 in complete remission [CR]1) or acute myeloblastic leukemia (n=37; 33 in CR1), who had received marrow grafts from HLA-identical siblings. The conditioning regimen included six 2-Gy fractions of total body irradiation, succeeded by cyclophosphamide at 120 mg/kg (with mesna) followed by four fractions of 1.5 Gy to lymphoid areas. Bone marrow (n=38) or peripheral blood mobilized donor mononuclear cells (n=12) were exposed ex vivo to CAMPATH-1 (IgM and complement, or IgG; antiCD52) antibodies, without any further posttransplantation immunosuppression. RESULTS Median patient age was 31 (range 14-51) years; 12 patients were 40 or older. Thirty-two patients were male. One patient died of pulmonary hemorrhage on day 10; another died on day 29 of interstitial pneumonitis. Except for one early death, all patients engrafted. Ten (21%) of the remaining 48 who were at risk, developed GVHD. In none was it greater than grade II. Eight patients developed serious viral infections. Four died of cytomegalovirus pneumonia, adenovirus hepatitis, and human immunodeficiency. Overall, 11 patients (22%) relapsed (4 of 33 acute myeloblastic leukemia in CR1) at a median of 235 (range 46-528) days. Mean posttransplantation follow-up was 1062 (median 560; range 10-4177) days. Thirty-three patients (66%) remained disease free at a mean of 1,118 (median 1439; range 159-4,177) days. For all patients, the performance status was between 82% and 100% (median 100). CONCLUSION T-cell depletion with CAMPATH-1 effectively prevents GVHD, particularly the severe acute forms, without leading to excessive risk of relapse in acute leukemia.

Myeloablative conditioning is well tolerated by older patients receiving T-cell-depleted grafts

Summary:Older age has been linked to increased transplant-related mortality from graft-versus-host disease (GvHD). Depletion of T cells from stem cell grafts seems to protect from complications of GvHD particularly in older patients. After myeloablative conditioning, patients with haematological malignancies received allogeneic grafts from HLA identical siblings. For GvHD prophylaxis, PBPC grafts were treated ex vivo with anti-CD52, and therapeutic doses of cyclosporin until day +90. Survival of patients younger or older than the population age median was analysed. In all, 62 consecutive patients with a median age of 42.5 years were studied. Death was procedure related in 17% and from relapse of malignancy in five. At a median, follow-up is 662 (7–2316) days, 74% survive disease free. The rate of haematopoietic recovery and treatment-related mortality was similar in both groups. A total of 73% of 30 individuals in the younger group and 75% (P=0.8) in the older cohort survive at a median follow-up of 444 and 806 days (P=0.4). GvHD occurred in 13% and was the only adverse factor for survival (P<0.04). Myeloablative conditioning is well tolerated up to the age of 59 in patients receiving T-cell-depleted grafts. This information is useful to more precisely select patients who would benefit most from reduced intensity conditioning schedules.

Campath-1 Abs ‘in the bag’ for hematological malignancies: the Cape Town experience

BACKGROUND We examined the strategy of T-cell depletion of HLA-identical sibling grafts for the prevention of GvHD, as well as disease control and overall survival. PATIENTS AND METHODS The myeloablative conditioning was radiation based. The source of stem cells was BM in 62, and cytokine-mobilized PBPC in 68 patients. GvHD prophylaxis was by ex vivo incubation of the stem-cell concentrates with Campath-1G (anti-CD52; n=76) or Campath-1H (n=54). RESULTS Patients receiving PBPC grafts were older (median 38.5) than those undergoing BMT (median 31; P=0.002). More patients in the PBPC group developed chronic GvHD (p<0.01). While no post-transplant GvHD prophylaxis was given to BMT recipients, prednisone 30 mg daily was prescribed to 12 and CYA for 90 days to a further 32 patients who had received PBPC grafts. Median follow-up was 1055 (range 28-4867) days. Although there was no difference in the survival between patients who received BMT or PBPC, death was from disease recurrence in 16 and nine (p=0.03; chi(2) test) subjects, respectively. Multivariate analysis showed that outcome was particularly favorable in those who were given<20 mg Campath-1 (survival: 28/39 versus 12/29; P=0.01), and in the subgroup of 30 patients who received Campath-1H and post-transplantation CYA. DISCUSSION In patients receiving BMT, Campath-1 Abs effectively prevent GvHD. For those treated with PBPC grafts, the combination of T-cell depletion and post-transplantation CYA is equally effective, without an obvious increase in disease recurrence.

Is There a Role for Autologous Stem Cell Transplantation for Patients with Acute Myelogenous Leukemia? A Retrospective Analysis

For patients with acute myelogenous leukemia (AML) who are unable to secure an acceptable HLA donor, the role of autologous stem cell transplantation (auto-SCT) has remained controversial. Its effectiveness remains unclear as, when analyzed on intention-to-treat strategies, a significant number do not undergo the procedure, whereas others seem to fail therapy from pretransplant recurrences. To improve our counseling to our patients on these 2 therapeutic options, we compared the outcome of patients in first remission of AML who actually underwent autologous or allogeneic transplantation. The choice for the type of graft was based on availability of HLA identical siblings. Patients received myeloablative conditioning followed by allogeneic or autologous cytokine mobilized peripheral blood stem cell transplantation. For prophylaxis of graft-versus-host disease (GVHD), grafts were incubated ex vivo with anti-CD52 antibodies and patients were prescribed cyclosporin until day 90. Patients were stratified by clinical and laboratory factors as well as cytogenetic risk. The endpoints were treatment-related mortality (TRM), disease-free survival (DFS), and overall survival (OS). The median presentation age for both transplant groups was 35 (14-60) years. Of the 112 consecutive patients achieving remission, autologous or allogeneic grafts were transplanted to 43 and 32 patients, respectively. There was no significant difference in the presentation clinical features, laboratory parameters, marrow morphology, or proportion of low and intermediate cytogenetic risk for both transplant options. Treatment mortality as well as relapse rate was similar (14% and 15%; 39% and 27%, respectively). At a median of 1609 and 1819 posttransplant days, 56% and 63% in each group survived. In univariate analysis performance status, cytogenetic risk, morphologic features of dysplasia, blast count, and lactate dehydrogenase (LDH) were significant factors for survival. Although for the entire group there was no difference in survival between both modalities, all patients with unfavorable cytogenetics receiving an autologous graft died of disease recurrence (3-year survival 35% versus 0%; P = .05). We conclude that patients with AML who have low or intermediate cytogenetic risk undergoing myeloablative conditioning followed by autologous or allogeneic T cell-depleted stem cell transplantation appeared to have similar outcome. However, those with unfavorable karyotype are unlikely to be cured with autologous grafts and are candidates for experimental modalities.

Combined Submyeloablative and Myeloablative Dose Intense Melphalan Results in Satisfactory Responses with Acceptable Toxicity in Patients with Multiple Myeloma

We studied in patients with multiple myeloma (MM) the efficacy, cost-effectiveness, and toxicity of a strategy of submyeloablative doses of Mel and stem cell support in the ambulatory setting, followed by a standard myeloablative dose transplant. Patients with recently diagnosed symptomatic MM received dexamethazone to induce clinical response. Cytokine mobilized peripheral blood progenitor cells (PBPC) were split into 2 aliquots and cryopreserved. Patients then received Mel 100 mg/m(2) (Mel100) and infusion of the first PBPC aliquot in an ambulatory facility. Individuals received standard neutropenia prophylaxis and no growth factor support, but were seen regularly at the clinic until recovery. The cost of this step was calculated in a cohort of 23 patients where information for the expenditure was available. Six months later patients were conditioned in the hospital with Mel 200 mg/m(2) (Mel 200) followed by nfusion of the second aliquot. This study tested the cost, effectiveness, and the toxicity of out-patient-based transplantation, as well as the rate of response (complete remission [CR], very good partial remission [VGPR], partial remission [PR], and stable disease [SD]) and overall survival (OS) of this strategy. Twenty-six female and 16 male patients, with a median age of 53 years (range: 33-68 years) and median Salmon & Durie clinical disease stage III (range: II-III) were studied. The paraprotein was IgA in 17%, IgG in 52%, and light chains in 26%. The median harvested CD34(+) x 10(6) cells/kg was 12.03 (2.25-55.4). The median interval between the 2 transplant procedures was 239 (105-376) days. The median Karnofsky presentation score was 40%, but improved to 80% after the Mel 100 and was 90% following Mel 200. Subsequent to MEL 100 response was complete (CR) in 7 and it was VGPR in 9. Mel 100 grade 3-4 toxicity was mainly hematologic, but 15 (36%) required hospital admission for a median of 5 days. The median cost of MEL100 and corresponding supportive therapy was U.S.

Intensified myeloablative therapy and autologous stem-cell transplantation for patients with AML: single center experience.

2,142.35. In addition, the total median cost of those who needed admission to hospital was U.S.

In stem cell transplantation, by limiting the morbidity of graft-versus-host disease tolerance to myeloablative conditioning is improved.

6,042.78. Thus, pooling costs from patients who needed or did not need admissions the average cost of this strategy was U.S.

Allogeneic stem cell transplantation with T cell-depleted grafts for lymphoproliferative malignancies.

3,546.50 per patient. Among Mel 200 patients, except for hematologic toxicity, no patient had greater than grade 2 side effects. On completion of the program, 20 (48%) patients achieved CR, a further 14 (33%) had VGPR, whereas 6 had PR. At a median follow-up of 659 days there were 8 deaths, 1 (2%) was related to the treatment procedures and 6 from disease progression; thus, the 1000 days OS was 73%. Significant adverse factors included older age, lower presentation Hb, and lower Karnofsky %. Nonparametric testing confirmed that good performance scores and VGPR or CR were associated with more favorable outcome. Importantly, these satisfactory results were obtained in the absence of the new biologic cell modifiers. Mel 100 was well tolerated in the outpatient setting and the overall strategy seems to be effective in inducing durable responses with acceptable toxicity.