ALBERT

Description: We evaluated the toxicity-profile, engraftment potential, and efficacy of fludarabine-based nonmyeloablative allogeneic HCT in patients with a variety of nonmalignant hematological disorders. Twenty three patients (median age 29 years; range 11–52) with nonmalignant hematological disorders including ATG refractory SAA (n=13), severe paroxysmal nocturnal hemoglobinuria (PNH: n=9), and pure red cell aplasia (PRCA; n=1) were transplanted from 5/99 – 8/2004 at the NHLBI. The majority of patients had an extensive transfusion history including 11/23 who had HLA allo-antibodies and 4/23 with allo-antibodies to RBCs. Conditioning with fludarabine (25 mg/m2 x 5 days), ATG (40mg/kg x 4 days) and cyclophosphamide (60mg/kg x 2 days) was followed by infusion of an un-manipulated G-CSF mobilized allograft from an HLA matched sibling (n=18), parent (n=2), or single antigen mismatched sibling (n=3). GVHD prophylaxis consisted of cyclosporine (CSA) either alone (n=2) or combined with mycophenolate mofetil (n=10) or mini-dose methotrexate (n=11). Despite a high prevalence of pre-transplant allo-immunization, all patients achieved sustained donor engraftment in both myeloid and T-cell lineages. Myeloid recovery (neutrophils 〉500cells/uL) occurred at a median 14 days post transplant (range 8–18 days). Conversion from mixed to full donor myeloid and T-cell chimerism occurred in all patients by 110 days post-transplant. CMV reactivation occurred in 11/21 patients at risk (KM probability 52%) without any cases of CMV disease. Grade II–IV and III–IV acute GVHD was the major transplant complication occurring in 13/23 (KM probability 60%) and 8/23 (KM probability 38%) patients respectively. Fourteen of 21 evaluable patients developed chronic GVHD (limited in 11 cases), which resolved completely with low-dose alternate day steroids and/or CSA in all but 1 case. One patient who received an allograft from his HLA matched father died 16 months post-transplant from complications related to chronic GVHD. With a median follow up of 25 months (range 1–64 months), 20/21 patients evaluable more than 100 days post-transplant survive in complete remission with full donor chimerism in all lymphohematopoietic lineages (KM probability of long-term survival 92.8 %-see figure ). Conclusion: Fludarabine-based nonmyeloablative transplantation achieves excellent donor engraftment and long-term disease free survival in heavily transfused and allo-immunized patients with ATG refractory SAA and other nonmalignant hematological disorders associated with bone marrow failure.

Description: Acute GVHD is a major contributor to morbidity and mortality following NST. A high incidence of grades II–IV GVHD occurs when cyclosporine A (CSA) alone is used as prophylaxis. Consequently, we investigated the effect of combining either mycophenolate mofetil (MMF) or methotrexate (MTX) with CSA on the incidence and severity of acute GVHD. Between 11/97 and 07/04, 185 consecutive patients (solid tumors n=116, hematologic malignancies n=48, non-malignant hematologic disorders n=21) underwent nonmyeloablative conditioning with fludarabine (125mg/m2) and cyclophosphamide (120mg/kg), followed by a G-CSF mobilized peripheral blood hematopoietic stem cell transplant from an HLA identical (n=177: 96%) or 5/6 antigen-matched (n=8: 4%) related donor. Twenty-four patients with a history of heavy RBC transfusions or those receiving a 5/6 HLA-matched transplant had anti-thymocyte globulin (40mg/kg/d x 4 days) added to their conditioning regimen. The initial cohort of patients (Group 1, n=66), received CSA alone (dose adjusted to maintain therapeutic serum levels) as GVHD prophylaxis. Due to the high incidence of severe acute GVHD in this group subsequent patients received CSA with either MMF (1 gram po bid; Group 2, n=82) or MTX (5mg/m2 days +1, +3, +6; Group 3, n=37). In all three groups, decisions regarding discontinuation of immunosuppression were based on the degree of donor T cell chimerism, presence of GVHD, and disease status in those with malignant diseases. In the absence of grade II–IV GVHD and disease progression, CSA (+/− MMF) was tapered slowly beginning on day +60. Baseline characteristics of patients in the three groups were compared using the Wilcoxon test for continuous variables and chi-squared tests for discrete variables. The three groups did not differ significantly in terms of age, sex, sex mismatch (female into male) and CD34 cell dose. Median follow-up in groups 1, 2 and 3 was 1901 days, 1248 days and 346 days respectively. The cumulative incidence of grades II–IV GVHD in these three groups was 56% (95% CI 44%–68%), 59% (95% CI, 48%–70%), and 34% (95% CI 18%–50%, p=0.11) respectively. The cumulative incidence of grades III–IV GVHD (30% vs. 34% vs. 16%, p=0.2) and the incidence of chronic GVHD (46% vs. 57% vs. 50%, p=0.49) were also similar in the three groups. Transplant related mortality was 15% (95% CI, 6%–24%) in group 1, 12% (95% CI, 5%–19%) in group 2 and 5% (95% CI, 0%–13%) in group 3 patients (p=0.44). The cumulative incidence of death from acute GVHD was 9% (95% CI, 0%–16%) and 2% (95% CI, 0–5%) respectively in groups 1 and 2, while no deaths from acute GVHD occurred in group 3. Overall survival in the three groups did not differ significantly (log-rank test, p=0.48), with medians 244 days (95% CI 196–402), 486 days (95% CI 306–620) and 438 days, (95% CI 210–662) respectively. The impact of adding MMF or MTX to CSA on disease-specific outcome in patients with malignant diseases was not assessed. Conclusion: There was a trend towards a lower incidence of grades II–IV GVHD in group 3 patients. However, despite the addition of either MMF or MTX to CSA, severe grade III–IV acute GVHD remains a major morbidity complicating NST. Additional strategies aimed at preventing GVHD and optimizing the management of established GVHD are needed to improve outcome following this approach.

Description: AMD3100 (AMD) is a bicyclam compound that inhibits the binding of stromal cell derived factor-1 to its cognate receptor CXCR4 present on CD34+ hematopoetic progenitor cells. Recently, investigators have shown that substantial numbers of CD34+ cells are released into circulation following a single injection of AMD, making this a potentially attractive mobilization agent for both autologous and allogeneic hematopoietic cell transplantation. Mononuclear cells transplanted in G-CSF (G) mobilized allografts mediate both desirable and undesirable post-transplant events (i.e. Graft-vs-tumor and GVHD); therefore, to determine the suitability of AMD mobilized products for allografting, we assessed the cellular content of apheresis collections obtained from the same donors mobilized with AMD vs G. Between 11/03–07/04, 6 healthy donors (male=3, female=3), median age 43 years (range 18–57), underwent a 15–25 liter apheresis following G mobilization (10mcg/kg/d x 5 days); 66–143 (median 82) days later, the same donors underwent repeat apheresis 6 hours following a single subcutaneous injection of AMD (240mcg/kg); the apheresis blood volume processed after AMD mobilization was matched to the volume processed after G mobilization in 5/6 donors. Data on peripheral blood (PB) and apheresis cellular content with both mobilization agents are shown in Table-1. AMD was well tolerated (no 〉 grade I toxicities) and effectively mobilized CD34+ cells in the majority of donors who had a previous successful G mobilization. Both drugs significantly increased PB CD34+ counts and the total WBC count, and absolute neutrophil counts (ANC), monocyte counts (AMC) and lymphocyte counts (ALC) above pre-mobilization baselines. In the PB, the increase in WBC count, ANC, and the CD34+ counts were significantly higher after G mobilization compared to AMD. In contrast, there was a trend towards a higher blood ALC increase following AMD administration compared to G. Apheresis collections mobilized with AMD contained similar numbers of mononuclear cells and CD3+ T-cells, higher numbers of CD19+ B-cells and lower numbers of monocytes and CD34+ cells compared to G mobilized collections; whether prior G mobilization negatively impacted the CD34+ cell content in AMD mobilized grafts can not be determined from this study. One patient failed mobilization with both G (CD34+ pre-count 6 /uL) and AMD (CD34+ pre-count 6 /uL); a trial investigating the efficacy of combining AMD with G in patients who fail to mobilize with G alone is currently being pursued. A detailed phenotypic analysis of lymphocyte subsets mobilized with G vs AMD3100 will be presented in a separate analysis.