Phase II study of a moderate-intensity preparative regimen with allogeneic peripheral blood stem cell transplantation for hematologic diseases: the Texas Transplant Consortium experience

Combination Therapy for Graft-versus-Host Disease Prophylaxis with Etanercept and Extracorporeal Photopheresis: Results of a Phase II Clinical Trial

Reduced-intensity conditioning (RIC) regimens minimize early toxicity after allogeneic hematopoietic cell transplantation (HCT) by placing greater reliance on establishing a graft-versus-leukemia effect (GVL). Because graft-versus-host disease (GVHD) and GVL are tightly linked, inhibition of T cell populations that cause GVHD may lead to an unintended increased risk of relapse in the RIC setting. Although not completely understood, etanercept and extracorporeal photopheresis (ECP) are thought to ameliorate GVHD without direct T cell inhibition. We hypothesized that adding these 2 agents to a standard GVHD prophylaxis regimen of tacrolimus and mycophenolate mofetil (MMF) would improve survival by reducing GVHD-related mortality without increasing relapse rates. Therefore, we conducted a prospective phase II clinical trial that incorporated tacrolimus, MMF, etanercept, and ECP as GVHD prophylaxis in 48 patients undergoing RIC unrelated donor transplantation. The preferred RIC was fludarabine 160 mg/m(2) + busulfan 6.4 mg/kg to 12.8 mg/kg ± total body irradiation 200 cGy. Etanercept .4 mg/kg (maximum dose, 25 mg) was given subcutaneously twice weekly for 8 weeks after HCT and ECP was given for 12 treatments, starting weekly on day 28 weekly and tapering off by day 180. The median age of the study patients was 60 (range, 18 to 71) years. Donors were 7/8 (n = 14, 29%) or 8/8 (n = 34, 71%) HLA matched. All patients engrafted neutrophils at a median of 12 days. The cumulative incidence of grades II to IV acute GVHD at day 100 was 46%, but it was typically sensitive to initial steroid treatment (84% day 56 complete response/partial response rate). Overall survival at 1 year in this older, frequently mismatched unrelated donor setting was excellent (73%) because of low rates of nonrelapse mortality (21%) and relapse (19%). However, this strategy was not effective at preventing a high incidence of chronic GVHD and late deaths led to a drop in 2-year survival, declining to 56%, reflecting a high incidence of chronic GVHD.

Pharmacology of dimethanesulfonate alkylating agents: busulfan and treosulfan

INTRODUCTION

Among the dimethanesulfonates, busulfan, in combination with other alkylating agents or nucleoside analogues, is the cornerstone of high-dose chemotherapy. It is used, and followed hematopoietic stem cell transplantation, for the treatment of various hematologic malignancies and immunodeficiencies. Treosulfan, which is a hydrophilic analogue of busulfan, was the first dimethanesufonate registered for the treatment of ovarian cancer. Recently, treosulfan has been investigated for the treatment of hematologic malignancies in combination with the same second agents before hematopoietic stem cell transplantation.

AREAS COVERED

This work reviews the pharmacological data of these two dimethanesulfonates alkylating agents. Specifically, the article looks at their chemistry, metabolism, anticancer activity, and their pharmacokinetics and pharmacodynamics.

EXPERT OPINION

Busulfan has been investigated widely for more than three decades leading to a large and precise handling of this agent with numerous studies on activity and pharmacokinetics and pharmacodynamics. In contrast, the behavior of treosulfan is still under investigation and not fully described. The complexity of treosulfan's metabolism and mechanism of action gives rise to the need of a deeper understanding of its pharmacological activity in a context of high-dose chemotherapy. Specifically, there is a great need to better understand its pharmacokinetics/pharmacodynamics relationship.

Reduced intensity transplantation for metastatic renal cell cancer with 2-year follow-up

Metastatic renal cell carcinoma (RCC) is a disease that is resistant to conventional systemic therapy. Nonmyeloablative allogeneic stem cell transplant has activity in patients with metastatic RCC. This approach has been used in related donor transplantation but there are limited data on outcomes in the setting of unrelated donor (URD) transplantation. This phase II trial assessed the efficacy, safety, and responses in 16 patients, 10 related and 6 URD transplants after a reduced intensity conditioning regimen and stem cell transplant as a treatment for metastatic RCC. Sixteen patients received a conditioning consisting of either fludarabine, cyclophosphamide (n=11) or fludarabine, total body irradiation (n=5) followed by transplantation from an HLA-matched sibling donor or a unrelated HLA-donor. Cyclosporine and mycophenolate mofetil were administered as posttransplant immunosuppression. Patients were monitored for engraftment by short tandem repeat for myeloid and lymphoid lineages and clinical response was assessed by serial imaging. All patients achieved donor chimerism, 7 patients developed acute, grades 2 to 3, graft-versus-host disease. Chronic graft-versus-host disease occurred in 6 patients and transplant-related mortality was 12%. Of the 10 related donors, 1 obtained a complete response, 3 had a partial response, and 3 had stable disease. In the 6 patients who underwent URD transplant, 1 obtained a complete response and 1 patient had stable disease. These results suggest that similar outcomes are possible where either related or URD were used as the stem cell source in reduced intensity stem cell transplant for metastatic RCC.

Reduced intensity conditioning using intravenous busulfan, fludarabine and rabbit ATG for children with nonmalignant disorders and CML

The major problems with busulfan/cyclophosphamide (Bu/Cy)-containing conditioning regimens are acute toxicities and graft failure. To decrease acute toxicities, we have prospectively evaluated a reduced intensity conditioning (RIC) regimen using targeted dosing of i.v. busulfan, fludarabine, and rabbit ATG (Bu/Flu/rATG) in children with diagnoses that historically would have been conditioned with Bu/Cy regimens. Nineteen pediatric patients were enrolled in the study. The donors included HLA-matched and one antigen-mismatched unrelated volunteers (n = 11), unrelated cord blood (n = 1), and related donors (n = 7). Four patients developed graft failure, which occurred between 1 and 8.5 months post transplant. All four of them underwent a second transplantation and 3/4 are alive without evidence of disease. The mean follow-up of living patients is 29.5 +/- s.d. 11 months. Despite excellent 2-year post-transplant overall survival (89 +/- s.d.7%) and event-free survival (74 +/- s.d.10%), the study was closed prematurely due to high graft failure rate (21%). Receiving a transplant from a mismatched unrelated donor was identified as a risk factor for graft failure. The Bu/Flu/rATG RIC regimen was very well tolerated, resulted in excellent overall survival, and provided sustained engraftment in patients undergoing transplant from matched sibling and unrelated donors. However, it did not provide sustained engraftment in the majority of children with nonmalignancies undergoing mismatched unrelated donor transplants.

Bloodless (transfusion-free) hematopoietic stem cell transplants: the Mexican experience

We have analyzed the transfusion requirements of a group of 132 peripheral blood stem cell transplants from a single institution (73 allografts and 59 autografts) over a 10-year period. The allografts were conducted using the 'Mexican' nonmyeloablative conditioning regimen, while the autografts were given single-day high-dose melphalan. For the allografts, the median number of transfused packed red blood (PRBC) cell units was 1 (range 0-22), while the median number of platelet transfusion (PLT) sessions was 1 (range 0-9); 45% of allografted individuals did not require PRBC transfusions and 35% did not require PLT. For autografts, the median number of PRBC units was 2 (range 0-21), while the median number of PLT was 2 (range 0-21); 33% of autografted individuals did not require PRBC and 25% did not require PLT. We conclude that, by using certain preparative regimens, both allo and auto hematopoietic stem cell grafts can be conducted without the transfusion of blood products.

Tumor Vaccination after Allogeneic Bone Marrow Cell Reconstitution of the Nonmyeloablatively Conditioned Tumor-Bearing Murine Host

Allogeneic bone marrow cell reconstitution of the nonmyeloablatively conditioned host is supposed to provide an optimized platform for tumor vaccination. We recently showed that an allogeneic T cell-depleted graft was well accepted if the tumor-bearing host was NK depleted. Based on this finding, a vaccination protocol in tumor-bearing, nonmyeloablatively conditioned, allogeneically reconstituted mice was elaborated. Allogeneically reconstituted mice, bearing a renal cell carcinoma, received tumor-primed donor lymph node cells (LNC), which had or had not matured in the allogeneic host. Primed LNC were supported by tumor lysate-pulsed dendritic cells, which were donor or host derived. Optimal responses against the tumor were observed with host-tolerant, tumor-primed LNC in combination with host-derived dendritic cells. High frequencies of tumor-specific proliferating and CTLs were recorded; the survival time of tumor-bearing mice was significantly prolonged, and in >50% of mice the tumor was completely rejected. Notably, severe graft-vs-host disease was observed in reconstituted mice that received tumor-primed LNC, which had not matured in the allogeneic host. However, graft-vs-host was not aggravated after vaccination with tumor-primed, host-tolerant LNC. Thus, the LNC were tolerant toward the host, but not toward the tumor. The finding convincingly demonstrates the feasibility and efficacy of tumor vaccination after allogeneic reconstitution of the nonmyeloablatively conditioned host.

Fludarabine and once-daily intravenous busulfan for allogeneic bone marrow transplantation for Chediak-Higashi syndrome

An HLA-identical sibling bone marrow transplant was done for a patient with Chediak-Higashi syndrome. The preparative regimen included intravenous fludarabine (40 mg/m2/dx4) and busulfan (130 mg/m2/dx4). Busulfan was given once daily. Pharmacokinetic studies showed the area under the concentration-time curve of the once-daily intravenous busulfan was similar to that seen with the total daily dose administered with an every-6-hourly regimen. Toxicity was minimal. Myeloid engraftment occurred on day +17 and donor chimerism was complete. Fludarabine and once-daily intravenous busulfan is well tolerated and is adequate for engraftment of sibling transplant in Chediak-Higashi syndrome.

Decreased transfusion requirements in patients given stem cell allografts using a non-myeloablative conditioning regimen: a single institution experience

We report our experience of allogeneic peripheral blood stem cell transplantation using non-myeloablative conditioning regimens delivered and supported on an outpatient basis. A group of 44 patients underwent 47 allograft procedures using peripheral blood stem cells. Approximately one third of the individuals did not require red blood cells transfusions: the median of transfused red blood cells units was 1 (range 0-10). In addition one out of three did not require platelet transfusions either, the median of platelet transfusions being 1 (range 0-6). In fourteen allografts (30%) neither red blood cells nor platelet transfusions were used. An inverse correlation was found between the number of CD34 cells infused and the PRBC and PLT transfusion requirements, those patients receiving high numbers of CD34 cells needing fewer transfusions of both PRBC and platelets. The possibility of conducting allografts without transfusion of blood products in some patients may result in a decrease in both cost and the risks stemming from exposure to human blood derivatives.