New sequential treatment with chemotherapy and reduced‐intensity conditioning for allogeneic stem‐cell transplantation in very high‐risk acute myeloid leukemia
Authors: Thomas Cluzeau, Muriel De Matteis, Nicolas Mounier, Lionel Mannone, Nicole Gratecos, Michel Ticchioni, Antoine Thyss, Sophie Raynaud, Jill‐Patrice Cassuto, Anne Sirvent
Journal: American Journal of Hematology (2011)

A new sequential regimen for allogeneic stem-cell transplantation, comprising cytoreductive chemotherapy immediately followed by reduced-intensity conditioning (RIC), was evaluated in 17 intensively treated patients with refractory or early relapsed acute myeloid leukemia (AML). Cytoreductive chemotherapy comprised thiotepa (3 × 200 mg/m2), etoposide (3 × 200 mg/m2) and six mercapto-purine (75 mg/m2 for 14 days) followed 2 days later, by RIC consisting of busilvex, Fludarabine and antithymocyte globulin. For six patients, the donor was a sibling and for 11, unrelated. The results showed that the procedure was safe. There were seven transplant-related deaths, mainly due to acute graft-versus-host disease and/or severe infection. Complete remission was observed in 13 patients at post-transplant Day 30. With a median follow-up of 14 months, overall survival and relapse-free survival were 29.4 and 17.7%, respectively. These results indicate a degree of antileukemia activity, which could probably be improved. The identification of new diagnostic and prognostic markers and the introduction of novel targeted therapies, as well as better management of patients in clinical trials, have improved the outcome of patients with acute myeloid leukemia (AML) [1, 2]. However, patients with initially refractory disease or those who relapse soon after diagnosis still have a poor prognosis. Allogeneic stem-cell transplantation (SCT) is the most effective antileukemic treatment [3, 4]. The graft-versus-leukemia (GvL) effect seems to play a more important role than the intensity of the preparative regimen [5, 6]. Schmid et al. first described a sequential regimen consisting of a short, intensive course of chemotherapy to reduce the leukemia burden, followed by reduced intensity conditioning (RIC) for alloSCT [7]. With this new strategy, known as the FLAMSA-RIC regimen, 2-year overall survival (OS) and leukemia-free survival were 42 and 40%, respectively. The FLAMSA regimen is a combination of fludarabine, high-dose cytarabine, and amsacrine. We postulated that leukemic cells had become resistant to those drugs already used in induction or consolidation treatment, and therefore, we chose other antileukemic drugs for cytoreduction. This retrospective study was conducted at our institution from December 2004 to December 2009. Written informed consent was obtained from each participating patient, and each patient was treated with usual salvage protocol of our hematologic unit for refractory or early relapsed AML. Patients were enrolled if they had developed relapsed AML within 1 year of complete remission (CR), or refractory AML after failure of induction chemotherapy (superior at 5% blasts after induction). Additional inclusion criteria were aged between 18 and 65 years and the availability of a related or unrelated donor. Recipients and donors were typed at high-resolution level at A, B, C, DRB1, and DQB1 loci by sequence-based typing. Exclusion criteria were comorbidities (creatinine clearance below 50 mL/min, bilirubin or aminotransferases more than 3 above the upper limit of normal, and a cardiac ejection fraction of less than 30%), an ECOG index above 2, and age exceeding 65 years. From Days −20 to −18, cytoreduction chemotherapy comprised, per day, 200 mg/m2 intravenous (IV) thiotepa, administered over 15 min, and 200 mg/m2 IV etoposide, administered over 1 hr, and from Days −20 to −6, 75 mg/m2/day oral 6 mercapto-purine to move away the toxicity of first step and to maintain an antileukemetic activity before second step of protocol. RIC consisted of 4 × 0.8 mg/kg Busilvex/day on Days −4 and −3, 30 mg/m2/day fludarabine from Days −5 to −1 and 2.5 mg/kg/day rabbit antithymocyte globulin on days −2 and −1 for HLA-identical siblings and from Days −3 to −1 for unrelated or mismatched donors. Patients transplanted with cord blood were given radiation-based RIC with 50 mg/kg cyclophosphamide on Day −6, 40 mg/m2/day Fludarabine from Days −6 to −2 and 2Gy total body irradiation on Day −1 [8]. GvHD prophylaxis consisted of cyclosporine from Day −1 for all patients except those transplanted with cord blood who were given cyclosporine combined with mycophenolate mofetil (15 mg/kg bid), starting from Day −3 to Day 30. Standard infection prophylaxis was used. Engraftment, disease response, and chimerism were assessed at day 30 post-transplantation with bone marrow (BM) aspiration. CR was defined as less than 5% blasts with no evidence of BM dysplasia and more than 1,500 neutrophils/L in peripheral blood. Donor chimerism in peripheral CD3 positive cells and unfractionated BM was studied at post-transplantation Days 30 and 100 using multiplex polymerase chain reaction (PCR) amplification of short tandem repeat markers [9]. Regimen-related toxicity and GvHD were respectively graded using NCI criteria (v 4.0) and Glucksberg criteria [10]. The safety and toxicity of this regimen were the primary endpoints. Secondary, endpoints included the response at Day+30, and the incidence of acute GvHD (aGvHD), OS, and relapse-free survival (RFS) 1 year after transplantation. OS and RFS were estimated by Kaplan–Meier plots. Data were analyzed by December 31st, 2009. Seventeen patients with refractory or early relapsed AML were included in this study. Patients' characteristics are given in Table I. The median age of the cohort at transplantation was 53 years (range, 32–64). Patients had been intensively treated before beginning the sequential chemotherapy: thus, 15 had at least two previous courses of chemotherapy and four had one previous failed allogeneic SCT. All patients had active disease before beginning the transplantation procedure with a least 20% leukemic blasts in BM. Donor characteristics are shown in Table I. Donors for 6/17 patients were HLA-identical siblings. Of the 11 unrelated donors, eight were “10/10” matched, whereas three exhibited one mismatch at HLA class I loci. All patients had developed profound pancytopenia by the end of the cytoreduction chemotherapy. Evaluation of the response at this point in the procedure showed the presence of hypocellular BM without blasts in 11 patients. Two patients died before transplantation, of severe sepsis while in aplasia. For the 15 remaining patients, the median time to engraftment from transplantation was 21 days, and the median duration of aplasia from the beginning of the procedure was 30 days (range, 21 to 46). Thirteen of these 15 engrafted patients (87%) were in CR at post-transplant Day 30. Chimerism analysis was performed on BM cells at Days +30 and +100 in 10 and 6 patients, respectively. Total donor chimerism with more than 95% of donor cells was observed in four patients at Day +30 and three at Day +100. Acute GvHD grade II to IV [11] occurred in seven patients (Table I). All patients were treated with corticosteroids: two patients achieved CR and five needed a second line of treatment consisting of inolimomab and/or extracorporeal photopheresis. Acute GvHD was considered a contributing cause of death in four patients. One patient developed limited chronic GvHD. Seven patients died of transplant-related complications at a median of 1.3 months after transplantation (range, 0–4). Regimen-related toxicities are given in Table I. Infectious complications were encountered in 14 patients. Overall, six episodes of grade III/IV regimen-related organ toxicity were observed. The affected organs were the liver (n = 3), and the mucositis (n = 3). Two patients died before engraftment, and 15 were alive at Day +30, 13 of them in CR. At the time of the last analysis after a median follow-up of 14 months (range, 4–57), five patients were alive, all in continuous CR. Leukemia relapse occurred in eight patients at a median of 3 months after transplantation (range, 1.2–15.4), and five of them died of leukemia. None of the patients had prophylactic or therapeutic donor lymphocyte infusion. After a median follow-up of 14 months, OS and RFS were, respectively, 29.4% (95% CI, 17.4%–41.4%) and 17.7%, (95% CI, 5.7%–29.7%, Fig. 1). The quality of life of the survivors was estimated by the Karnofsky score 1 year after transplantation: median score was 100% (range, 60–100%). (A) Relapse-free survival and (B) overall survival. These results confirm the safety of our approach in a small cohort of patients. All patients indeed had active leukemia at the beginning of the procedure and were intensively pretreated. Unsurprisingly, the main causes of treatment failure were relapse, severe aGvHD and infection. Other toxicities, which involved the liver and mucosal tissues, were manageable. Although our results look disappointing, with 1-year OS of 29.4% and 1-year RFS at 17.7%, they seem comparable to those published by Schmid et al., in the subgroup of patients who had more than two courses of previous chemotherapy [12]. The results of this study highlight the difficulty of achieving long-term survival in patients who are not in CR. The concept of a sequential regimen seems a promising strategy for these patients, but several ways of improving the results must be explored. The place of new drugs, including gemtuzumab ozogamicin and clofarabine, during either cytoreductive chemotherapy or RIC should be considered to improve control of the leukemic clone. At present, no data are available regarding the ongoing clinical trials that include Clofarabine in the conditioning regimen of patients with refractory leukemia. Recently, Richardson et al. [13] reported OS and disease-free survival of 60% each after a median follow-up of 7.5 months. Buchholtz et al. reported 15/25 patients in CR after a median follow-up of 7 months [14]. De Lima et al. have shown that gemtuzumab ozogamicin can be safely added to an RIC regimen [15]. Although the role of prophylactic transfusion of donor lymphocytes must be carefully evaluated in the setting of refractory AML, it may be another way of reducing the incidence of post-transplantation relapse. Shortening the duration of severe neutropenia by reducing the duration of conditioning may decrease the incidence of infectious complications and therefore the high rate of nonrelapse mortality observed in our study. Finally, the best timing for transplantation needs to be established. Nevertheless, hematopoietic SCT should probably be proposed earlier during the course of AML than it is presently performed. In summary, the results of our sequential cytoreduction chemotherapy combined with RIC are disappointing, although certain patients in our series may eventually achieve long-term survival. Nevertheless, a sequential regimen is feasible, as already shown in larger published series. All available data on sequential regimens should now be collected and studied, to design prospective studies featuring new drugs with potent antileukemic activity and better use of the GvL effect. Cluzeau Thomas*, De Matteis Muriel , Mounier Nicolas*, Mannone Lionel*, Gratecos Nicole*, Ticchioni Michel , Thyss Antoine§, Raynaud Sophie , Cassuto Jill Patrice*, Sirvent Anne*, * Department of Hematology, CHU Nice, Nice, France, Laboratory of Immunology, CHU Nice, Nice, France, Laboratory of Hematology, CHU Nice, Nice, France, § Department of Oncology, Centre Antoine Lacassagne, Nice, France.