Thiotepa-based reduced intensity conditioning regimen: a 10 year follow up

Thiotepa-fludarabine-treosulfan conditioning for 2nd allogeneic HCT from an alternative unrelated donor for patients with AML: a prospective multicenter phase II trial

Therapeutic options for patients with AML relapsing after allogeneic HCT range from chemotherapy or hypomethylating agents with or without donor lymphocyte infusions to a 2nd allogeneic HCT. Available data are based on retrospective single center or registry studies. The aim of this multicenter trial was to investigate prospectively intensive conditioning with Thiotepa, Fludarabine and Treosulfan (TFT) for 2nd allogeneic HCT from an alternative unrelated donor in patients with AML relapse > 6 months after a 1st allogeneic HCT. Primary endpoint was disease-free survival (DFS) at one year after 2nd HCT. 50 patients median age 53.5 years, in CR/PR (34%) or active relapse (66%) were included. 33 of 38 patients (86.8%) with available data achieved CR 100 days post transplant. 23 patients were alive and free of relapse at primary endpoint one year after 2nd HCT (DFS rate 0.46, 95%-CI (0.32-0.61). Three-year rates of DFS, relapse, non-relapse mortality, and overall survival were 0.24, 95%-CI (0.13-0.36); 0.36 (0.25-0.52); 0.40 (0.29-0.57); and 0.24 (0.13-0.37). Second HCT with TFT conditioning is feasible and has high anti-leukemic efficacy in chemosensitive or refractory AML relapse after prior allogeneic HCT. Still, relapse rates and NRM after 2nd allogeneic HCT remain a challenge. The trial is registered in the German Clinical Trials Registry (number DRKS00005126).

Reduced intensity versus non-myeloablative conditioning regimen for haploidentical transplantation and post-transplantation cyclophosphamide in complete remission acute myeloid leukemia: a study from the ALWP of the EBMT

The optimal conditioning regimen prior haploidentical stem cell transplantation (Haplo-SCT) with post transplantation cyclophosphamide (PT-Cy) for acute myeloid leukemia (AML) remains unknown. A non-myeloablative conditioning (NMAC) regimen (cyclophosphamide + fludarabine + TBI 2 Gy [CyFluTBI]) is a safe approach, but relapse incidence remains high in this setting. Alternatively, a reduced intensity conditioning (RIC) regimen combining thiotepa and reduced-dose busulfan with fludarabine (TBF) may decrease AML relapse. However, an excess of toxicity may counterbalance this potential benefit. We retrospectively compared CyFluTBI vs. TBF in CR AML patients who underwent Haplo-SCT with PT-Cy, in two different populations based on age. We analyzed 490 patients. In patients aged <60 years (n = 203), we observed a higher RI (HR = 3.59, 95% CI = 1.75-7.37, p < 0.01), lower LFS (HR = 1.98, 95% CI = 1.22-3.22, p < 0.01) and lower OS (HR = 1.73, 95% CI = 1.04-2.88, p = 0.04) in the CyFluTBI group, without significant difference in NRM. In older patients (n = 287), we observed that conditioning regimen did not significantly influence LFS (HR = 0.90, 95% CI = 0.56-1.44, p = 0.65), OS (HR = 0.81, 95% CI = 0.49-1.32, p = 0.39) and RI (HR = 1.78, 95% CI = 0.90-3.50, p = 0.10), but showed that CyFluTBI was associated with a significantly lower risk of NRM (HR = 0.48, 95% CI = 0.25-0.92, p = 0.03). Thus, younger patients seem to benefit from conditioning intensification from CyFluTBI to TBF regimens prior PT-Cy Haplo-SCT for CR AML, while older ones do not.

Dose intensity for conditioning in allogeneic hematopoietic cell transplantation: can we recommend "when and for whom" in 2021?

Allogeneic hematopoietic stem-cell transplantation is a potentially curative therapy for various hematologic diseases. An essential component of this procedure is the pre-transplant conditioning regimen, which should facilitate engraftment and reduce or eliminate tumor cells. The recognition of the substantial association of a graft-versus- tumor effect and the high toxicity of the commonly used conditioning regimen led to the introduction of more differentiated intensity strategies, with the aim of making hematopoietic stem-cell transplantation less toxic and safer, and thus more applicable to broader populations such as older or unfit patients. In general, prospective and retrospective studies suggest a correlation between increasing intensity and nonrelapse mortality and an inverse correlation with relapse incidence. In this review, we will summarize traditional and updated definitions for conditioning intensity strategies and the landscape of comparative prospective and retrospective studies, which may help to find the balance between the risk of non-relapse mortality and relapse. We will try to underscore the caveats regarding these definitions and analyses, by missing complex differences between intensity and toxicity as well as the broad influences of other factors in the transplantation procedure. We will summarize evidence regarding several confounders which may influence decisions when selecting the intensity of the conditioning regimen for any given patient, according to the individual risk of relapse and non-relapse mortality.

Thiotepa, Busulfan, and Fludarabine Conditioning Regimen in T Cell-Replete HLA-Haploidentical Hematopoietic Stem Cell Transplantation

We report the outcomes of 51 patients who underwent unmanipulated haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with post-transplantation cyclophosphamide (PT-Cy) and antithymocyte globulin (ATG), from peripheral blood stem cells (PBSCs) or bone marrow, after receipt of a TBF (thiotepa, busulfan, and fludarabine) conditioning regimen. Their median age was 55 years (range, 16 to 72 years). Hematologic diagnoses included acute leukemias (n = 31), lymphoid neoplasm (n = 12), myeloproliferative neoplasm (n = 5), and myelodysplastic syndromes (n = 3). Thirty-seven patients (73%) were in complete remission. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mycophenolate for all patients, associated with ATG in 39 patients (76.5%). The median time to neutrophil engraftment was 17 days (range, 12 to 34 days). The cumulative incidences of grade II-IV and grade III-IV acute GVHD were 27.5% and 14%, respectively. In patients receiving a PBSC graft and ATG prophylaxis, grade II-IV aGVHD occurred in 16% of patients. The use of ATG and a lower thiotepa dose (5 mg/kg versus 10 mg/kg) were associated with a reduced cumulative incidence of grade II-IV acute GVHD (P = .03 and .005, respectively). The 2-year cumulative incidence of chronic GVHD was 29% and was significantly reduced to 13% with the lower thiotepa dose (P = .002). After a median follow-up of 25 months (range, 12 to 62 months), the cumulative incidences of nonrelapse mortality, relapse, overall survival (OS), disease-free survival (DFS), and GVHD-free, relapse-free survival (GFRFS) were 20%, 22.5%, 67%, 58%, and 51%, respectively. Pretransplantation disease status (complete remission versus others) was the main factor associated with OS, DFS, and GFRFS. In conclusion, the TBF conditioning regimen is an appealing platform in the haplo-HSCT setting with PT-Cy in terms of engraftment rate, toxicity, and disease control. We found no benefit of a thiotepa dose of 10 mg/kg compared with a dose of 5 mg/kg. ATG reduced the risk of acute GVHD without comprising outcomes.

Fludarabine-based reduced toxicity yet myeloablative conditioning is effective and safe particularly in patients with high-risk thalassemia undergoing allogeneic transplantation

INTRODUCTION

Thalassemia major (TM) is an inherited disorder caused by ineffective erythropoiesis. At the present time, allogeneic stem cell transplantation (allo-SCT) is a curative option. Conventional busulfan and cyclophosphamide based myeloablative conditioning regimens are limited by increased toxicity, especially in high-risk patients. Replacement of cyclophosphamide with fludarabine has reduced toxicity and nonrelapse mortality (NRM), thus improving outcomes. We analyzed long-term data of our fludarabine-based myeloablative, reduced toxicity protocol, specifically in high-risk patients.

METHODS

We retrospectively analyzed a cohort of 47 consecutive patients with TM undergoing allo-SCT from matched donors, using the fludarabine-based regimen (reduced toxicity regimen). The median age of the cohort was 10 years. Thirty-eight patients (80%) were in the high-risk and nine patients (20%) were in the low-risk category. The primary aim of this analysis was thalassemia-free survival (TFS).

RESULTS

The rejection rate was 11% within high-risk patients with NRM of 2%. With a median follow-up period of 7 years (1-15 years), the 10-year TFS in the entire cohort was 87%, and the overall survival (OS) was 97%. The 10-year TFS and OS among the low-risk and high-risk groups were 90% versus 84%, respectively (P = 0.45) and 100% versus 96%, respectively (P = 0.5), and both subsets of patients did equally well.

CONCLUSION

In conclusion, replacement of high-dose cyclophosphamide with fludarabine is well tolerated with minimal regimen-related toxicity and acceptable rejection rates, especially in high-risk patients.

Augmented myeloablative conditioning with thiotepa in acute myeloid leukemia - improved outcomes with similar toxicity

Myeloablative doses of busulfan (Bu) with fludarabine (Flu) have reduced toxicity, however, limited by an increased relapse rate. We aimed to improve outcome of Flu-Bu regimen by augmentation with thiotepa (TT) (10 mg/kg). Eighty-nine patients with AML, 44 patients conditioned with Flu-Bu (group 1), and 45 patients augmented with TT (Flu-Bu-TT, group 2), were retrospectively analyzed. Primary objectives were toxicity and outcomes. Major toxicities were comparable: mucositis (p = 1.0), sepsis (p = .7), severe venocclusive disease of liver (VOD) (p = 1.0), and non-relapse mortality (NRM) (22 vs. 22%, p = .7). Five-year disease-free survival was significantly better in group 2 compared to group 1 (62 vs. 38%, p = .02). Five-year overall survival (OS) showed trend toward benefit in group 2 (62 vs. 42%, p = .06). Lower relapse rate in group 2 (14 vs. 46%, p = .005) contributed to better outcomes. Augmented regimen has better disease-free survival (DFS) (mainly due to reduced relapse rate) and similar toxicities as compared to Flu-Bu. Key points  Assessing the addition of TT to myeloablative conditioning (Flu, Bu) in patients undergoing allogeneic stem cell transplant for acute myeloid leukemia with regard to relapse rate, disease-free survival and toxicity.  Addition of thiotepa improves disease-free survival and shows trend toward benefit in overall survival, by reducing relapses without additional toxicity.

Sequential Conditioning with Thiotepa in T Cell- Replete Hematopoietic Stem Cell Transplantation for the Treatment of Refractory Hematologic Malignancies: Comparison with Matched Related, Haplo-Mismatched, and Unrelated Donors

The results of conventional allogeneic stem cell transplantation (SCT) in refractory hematologic malignancies are poor. Sequential strategies have shown promising results in refractory acute myelogenous leukemia (AML), but have not been validated in a haploidentical (Haplo) transplant setting. We have developed a new sequential approach combining chemotherapy with broad antitumor activity (thiotepa 10 mg/kg, etoposide 400 mg/m², and cyclophosphamide 1600 mg/m² from day -15 to day -10), followed after 3 days of rest by a reduced-intensity conditioning regimen (fludarabine 150 mg/m², i.v. busulfan 6.4 mg/kg, and thymoglobulin 5 mg/kg from day -6 to day -2). High-dose post-transplantation cyclophosphamide was added in cases with Haplo donors. Seventy-two patients (median age, 54 years) with a refractory hematologic malignancy (44 with acute myelogenous leukemia, 7 with acute lymphoblastic leukemia, 15 with myelodysplastic syndrome/myeloproliferative neoplasms, and 6 with lymphomas) were included in this retrospective multicenter study. Donors were Haplo (n = 27), matched related (MRD; n = 16), and unrelated (UD; n = 29). With a median follow-up of 21 months, the 2-year overall survival (OS) and event-free survival (EFS) were 54.7% and 49.3%, respectively, in recipients of Haplo transplants, 49.2% and 43.8%, respectively, in recipients of MRD transplants, and 37.9% and 28%, respectively, in recipients of UD transplants. Compared with UD, the outcomes were improved in Haplo in terms of the incidences of acute grade II-IV graft-versus-host disease (GVHD) (11.1% versus 41.4%; P < .001) and GVHD-free, relapse-free survival (44.4 versus 10.3%; P = .022). These results support the safety and efficacy of a thiotepa-based sequential approach in allogeneic SCT with a Haplo donor with post-transplantation immune modulation. Thus, in patients with refractory hematologic malignancies, there seems to be no benefit in searching for a UD when a Haplo donor is readily available.

Thiotepa-based conditioning versus total body irradiation as myeloablative conditioning prior to allogeneic stem cell transplantation for acute lymphoblastic leukemia: A matched-pair analysis from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The optimal conditioning regimen to employ before hematopoietic stem cell transplantation in acute lymphoblastic leukemia (ALL) is still undecided, and while cyclophosphamide/total body irradiation (Cy/TBI) is the most commonly used myeloablative regimen, there are concerns regarding long-term toxicity for patients conditioned with this regimen. Thiotepa-based conditioning is an emerging radiation-free regimen with recent publications indicative of comparable clinical outcomes to TBI-based conditioning. In this analysis of the acute leukemia working party of the EBMT, we performed a retrospective matched-pair analysis, evaluating the outcome of adult patients with ALL who received thiotepa-based conditioning (n = 180) with those receiving Cy/TBI conditioning (n = 540). The 2-year leukemia-free survival and overall survival (OS) rates of both conditioning regimens were comparable, 33% for thiotepa [95% confidence interval (CI): 26.4-42.8] versus 39% for Cy/TBI (95% CI: 34.8-44.5] (P = .33) and 46.5% [95% CI: 38.6-56.1] versus 48.8% [95% CI: 44.2-54] (P = .9), respectively. There was no significant difference between the two regimens in the incidence of either acute graft versus host disease (GVHD) or chronic GVHD. Multivariate analysis demonstrated increased relapse incidence for thiotepa conditioning compared to Cy/TBI (HR = 1.78, 95% CI, 1.07-2.95; P = .03) which did not affect OS. Our results indicate that thiotepa-based conditioning may not be inferior to Cy/TBI for adult patients with ALL.

Thiotepa-based conditioning for allogeneic stem cell transplantation in acute lymphoblastic leukemia-A survey from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

In this study, we analyzed a thiotepa-based conditioning regimen for allogeneic stem cell transplantation in adults with acute lymphoblastic leukemia, using the EBMT database. A total of 323 patients were identified. The median age was 43 years. Disease status at transplant was first complete remission (CR1) in 48.9%, CR2 in 21.7%, CR3 in 6.2%, while 23.2% of the patients had an active disease at the time of transplant. This was performed from a HLA-matched sibling (49.8%) or a matched-unrelated donor (51.2%). The incidence of acute graft-vs.-host disease (GvHD) (grade > II) was 26.6%, while chronic GvHD occurred in 35.9% of the patients at 1 year (24.6% with extensive disease). With a median follow-up of 16.8 months, the nonrelapse mortality was 12.4 and 25.3% at 100 days and 1 year, respectively. The relapse incidence at 1 year was 33.3% with no difference for patients in CR1 (27%). The one-year leukemia-free survival (LFS) and overall survival (OS) were 57 and 66%, respectively for the entire cohort and 50 and 66%, respectively in patients in CR1. Thiotepa/busulfan ± melphalan (n = 213) in comparison to thiotepa/other (n = 110) conditioning regimen resulted in higher relapse incidence at 1 year (34.9 vs. 30.3%, P = 0.016) and lower LFS (38.8 vs. 45.9%, P = 0.0203), while nonrelapse mortality (23.8 vs. 26.3%, n.s.) and OS (59.6 vs. 51.1%, P = 0.109) did not differ. This large study suggests that a thiotepa-based conditioning for allogeneic transplantation in acute lymphoblastic leukemia is feasible and effective, with the main outcomes being comparable to those achieved with other regimens. Am. J. Hematol. 92:18-22, 2017. © 2016 Wiley Periodicals, Inc.

Safety and efficacy of thiotepa-based conditioning for allogeneic transplantation in AML: a survey from the ALWP of the EBMT

This study evaluated the safety and efficacy of thiotepa-based regimens before allogeneic stem cell transplantation in 310 adult patients with AML. Disease status at the time of transplantation was CR1 in 50%, CR2+ in 23.5% and advanced disease in 26.5%. Transplantation was performed from haploidentical (35%), matched sibling (27%), unrelated (20%) or cord blood (18%) donors. As for safety: mucositis occurred in 46.8% of the patients and the cumulative incidence (CI) of sinusoidal obstruction syndrome was 4.0%. With a median follow-up of 37 months, the CI of acute GvHD grade>II was 26.5%, whereas CI of chronic GvHD was 28.1% at 3 years. CI for non-relapse mortality at 3 years was 38.4%, 49.7% and 45.4% for patients in CR1, CR2+ and advanced disease, respectively (P=0.10). Relapse incidence at 3 years was 20.2, 30.7 and 40.6% in these three respective groups (P=0.002). CI for 3-year leukemia-free survival and overall survival were 41.4% and 45.6% (CR1), 19.6% and 27.7% (CR2+), and 13.9% and 13.6% (advanced disease), respectively (P<10^-4 for both). Our data suggest that thiotepa-based conditioning therapy in AML is feasible, effective and safe, as investigated for sinusoidal obstruction syndrome and mucositis.

Thiotepa-based versus total body irradiation-based myeloablative conditioning prior to allogeneic stem cell transplantation for acute myeloid leukaemia in first complete remission: a retrospective analysis from the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation

Thiotepa is an alkylating compound with an antineoplastic and myeloablative activity and can mimic the effect of radiation. However, it is unknown whether this new regimen could safely replace the long-established ones. This retrospective matched-pair analysis evaluated the outcome of adults with acute myeloid leukaemia in first complete remission who received myeloablative conditioning either with a thiotepa-based (n = 121) or a cyclophosphamide/total body irradiation-based (TBI; n = 358) regimen for allogeneic hematopoietic stem cell transplantation from an HLA-matched sibling or an unrelated donor. With a median follow-up of 44 months, the outcome was similar in both groups. Acute graft-versus-host disease grade II-IV was observed in 25% after thiotepa-containing regimen versus 35% after TBI (P = 0.06). The 2-yr cumulative incidence of chronic graft-versus-host disease was 40.5% for thiotepa and 41% for TBI (P = 0.98). At 2 yrs, the cumulative incidences of non-relapse mortality and relapse incidence were 23.9% (thiotepa) vs. 22.4% (TBI; P = 0.66) and 17.2% (thiotepa) vs. 23.3% (TBI; P = 0.77), respectively. The probabilities of leukaemia-free and overall survival at 2 yrs were not significantly different between the thiotepa and TBI groups, at 58.9% vs. 54.2% (P = 0.95) and 61.4% vs. 58% (P = 0.72), respectively. Myeloablative regimens using combinations including thiotepa can provide satisfactory outcomes, but the optimal conditioning remains unclear for the individual patient in this setting.