Sandeep Chunduri

Fludarabine/i.v. BU conditioning regimen: myeloablative, reduced intensity or both?

In this study, we utilized a conditioning regimen with fludarabine and myeloablative dose i.v. BU (12.8 mg/kg) (FluBU) in 36 adult patients (median age: 44 years, range: 18–61) with myeloid or lymphoid malignancies at standard risk (n=10) or high risk of relapse (n=26), who received an allogeneic hematopoietic SCT (HSCT) from HLA-matched related (n=16) or unrelated (n=20) donors. The source of hematopoietic stem cells was peripheral blood in 28 and marrow in 8 cases. Rabbit-antithymocyte globulin at 7 mg/kg was utilized in 21 patients. Acute GVHD grade II–IV was observed in 19% of the patients (grade III–IV in 14% of patients) and chronic GVHD in 11 of 30 evaluable patients (37%). At median follow-up of 737 days (range: 152–1737) for alive patients, overall survival rates in standard- and high-risk patients were 80 and 35%, respectively, and event-free survival rates were 70 and 31%, respectively. TRM was 10% in standard-risk and 19% in high-risk patients. Post transplant relapse was observed in 20% standard-risk and in 46% high-risk patients. FluBU conditioning regimen is associated with a limited hematologic and extrahematologic toxicity and with an antitumor activity comparable to other standard myeloablative regimens.

Reliability of a pretransplant i.v. BU test dose performed 2 weeks before myeloablative FluBu conditioning regimen

A pretransplant test dose of i.v. BU was previously used in pediatric patients undergoing a reduced-intensity allogeneic hematopoietic SCT (HSCT). Here, we used a BU test dose in 23 adult patients who were not pancytopenic and underwent a myeloablative allogeneic HSCT prepared with fludarabine and i.v. BU (FluBU). Pharmacokinetics (PK) of BU were calculated after a test dose (0.8 mg/kg) was performed 2 weeks before transplant. Targeted BU area under the curve (AUC) range was 4800–5200 μM min. The mean BU dose calculated after the test dose was 3.5±0.5 mg/kg. To validate the test dose, PK studies were repeated in 17 patients after the first dose of BU during the conditioning regimen. An AUC below the therapeutic value of 4000 μM min was observed in 23% of the patients receiving a wt-based dose and in 0% of patients whose dose was calculated on the basis of the test dose (P=0.03). In patients who had a test dose, a significant correlation (P<0.0001) between the first and subsequent doses of BU during the conditioning regimen was observed. Our findings may allow more centers to pursue transplant strategies with targeted BU by overcoming the time limitation for PK studies during the conditioning regimen.

Prolonged responses after autologous stem cell transplantation in African-American patients with multiple myeloma.

Multiple myeloma (MM) has a double incidence in African-American (AA) than in non-AA patients and previous studies have shown a higher mortality in the former patient population. Here, we retrospectively analyzed the results of autologous stem cell transplantation (ASCT) in 38 AA and 32 non-AA consecutive patients. The two groups were comparable at diagnosis for age, stage of the disease, cytogenetic abnormalities, β2 microglobulin and albumin blood levels, and plasma cell marrow infiltration. The rates of complete and partial response observed in AA and non-AA patients after induction chemotherapy (9 and 42 vs 13 and 33%) and at 2 months (31 and 25 vs 30 and 20%) following ASCT were similar. At 6 months after ASCT, a greater relapse rate was observed in non-AA patients (P=0.009). At a median follow-up of 26 months, AA patients had a greater event-free survival (P=0.02) than non-AA patients, whereas overall survival was comparable in the two groups. The initial finding that AA patients with MM, compared to non-AA patients, had more prolonged responses and comparable survival after ASCT suggests that intensified chemotherapy is equally effective in patients of various ethnicities.

Comparable kinetics of myeloablation between fludarabine/full-dose busulfan and fludarabine/melphalan conditioning regimens in allogeneic peripheral blood stem cell transplantation.

Fludarabine was utilized in the conditioning regimen of 30 adult patients undergoing an allogeneic hematopoietic stem cell transplant. In 18 patients it was combined with full-dose busulfan (FluBu) as a myeloablative regimen and in 12 cases with melphalan (FluMel) as a reduced intensity conditioning (RIC) regimen. Patients in the FluBu group were younger than in the FluMel group (P=0.03). Of 30 patients, 24 received peripheral blood stem cells (PBSC) whereas six patients in the FluBu group received bone marrow cells. The hematological toxicity of each regimen was evaluated by analyzing the kinetics of the neutropenia induced by preparative regimens and the time to recovery of the absolute neutrophils count (ANC) and platelets post transplantation. In PBSC transplants, the median day of severe neutropenia (<500 ANC/μl) occurred on day +6 after the FluBu regimen and on day +3 after FluMel (P=ns), whereas both groups had a duration of severe neutropenia of 9 days and a comparable time for ANC and platelet engraftment. Extra-hematological toxicities were also comparable in the two groups. These findings suggest that the hematological and extra-hematological toxicities induced by fludarabine/full-dose i.v. busulfan are similar to those induced by a standard RIC regimen such as fludarabine/melphalan.

Pulmonary extramedullary hematopoiesis in patients with myelofibrosis undergoing allogeneic stem cell transplantation

We examined the lung function of 11 patients with intermediate/high risk myelofibrosis undergoing allogeneic hematopoietic stem cell transplantation (HSCT). In 3 patients, chest computerized tomography (CT) scans revealed multiple pulmonary nodules with extramedullary hematopoiesis that disappeared

Cord Blood Nucleated Cells Induce Delayed T Cell Alloreactivity

Cord blood (CB) mononuclear cells (MNCs) can be transplanted in HLA mismatched recipients with limited graft rejection or graft-versus-host disease (GVHD). Previous studies have shown that naive T cells and hyporesponsive dendritic cells are largely represented in CB. Data presented here demonstrate that CB MNCs are unable to stimulate allogeneic T cell proliferative or cytotoxic responses in standard in vitro assays. However, a suppressive effect of CB MNCs was ruled out because purified CD34(+) cells or CD14(+) monocytes stimulated T cell responses that were not inhibited by add-back of CB MNCs. The lack of antigen-presenting cell (APC) activity of CB MNCs in primary mixed lymphocyte culture (MLC) did not induce allogeneic T cell anergy. In fact, rechallenge of T cells with CB CD34(+) cells, or immature monocyte-derived dendritic cells (iMo-DCs) in secondary MLC induced potent T cell proliferative responses. A delayed APC activity of CB MNCs was observed after stimulation with irradiated allogeneic T cells for 6 days, likely because of the upregulation of CD86 and HLA-DR on CB cells. Cytotoxic lymphocytes (CTL) were generated after stimulation of blood T cells with CB MNCs for 4 weeks or CB-derived iMo-DCs for 1 week. Concomitant stimulation of T cells with CB iMo-DC obtained from 2 CB units resulted in the generation of CTLs specific for each CB, independently of the CB:CB cell ratio. These data suggest that the APC activity of CB cells possibly increases posttransplant, and may contribute to delayed graft rejection and/or acute and chronic GVHD.

Does post-transplant treatment with imatinib mesylate inhibit graft-versus-leukemia?

We read with interest the recent article by Cwynarski et al demonstrating that imatinib mesylate can prevent human T-cell responses to CD3/CD28 or PHA stimulation. The blocking mechanism of imatinib shown by the authors is direct on T cells, does not cause induction of apoptosis and is reversible. Therefore, the authors suggest that the use of imatinib after allogeneic stem cell transplantation may result in a reduced graft-versus-leukemia effect. Similar in vitro results were also reported in another recent study. Indeed, these experimental findings might explain a clinical case that we observed, which raises the question if patients who undergo an allogeneic stem cell transplantation, after failing to achieve a cytogenetic response on imatinib, may accelerate their relapse upon restarting imatinib post-transplant. Our case relates to a 49-year-old patient with a t(1;9;22) chronic myeloid leukemia (CML) in chronic phase, diagnosed in 2002. The patient was initially started on imatinib mesylate and achieved a hematological remission, but only a minor cytogenetic response despite dose escalation of imatinib to 800 mg. For this reason, he received an allogeneic G-CSF mobilized peripheral blood stem cell transplant from an HLA-matched related brother in May 2003. The transplant was conditioned with fludarabine 120 mg/m and busulfan 12.8 mg/kg i.v. Graft-versus-host disease (GVHD) prophylaxis included standard tacrolimus plus methotrexate, and thymoglobulin at 4.5 mg/kg. He achieved full engraftment at day 30 after transplant. At 4 months post-transplant, because of chimerism o90%, detectable disease at molecular level, and absence of GVHD, the immunosuppression was stopped. Figure 1 illustrates the relationship between chimerism levels and molecular minimal residual disease, tested by RQ-PCR, at different time-points. At 8 months after transplant, the chimerism was still 84%. Therefore, imatinib was restarted with the aim of obtaining some effect on the tumor burden to help possibly the donor cells to achieve a full chimerism and a complete molecular remission. Three months later, instead, imatinib was stopped because the chimerism had progressively slightly decreased and molecular p210 levels were unchanged. Moreover, 1 month later a cytogenetic relapse in 30% of blood cells, a 12% molecular minimal residual disease, and a drop of

The use of blood conservation methods in addition to erythropoietin allows myeloablative allogeneic stem cell transplantation without the use of blood products.

The use of blood conservation methods in addition to erythropoietin allows myeloablative allogeneic stem cell transplantation without the use of blood products