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Highlights • The impact of donor age and sex but not CMV matching is comparable with that of single HLA disparity on survival after HSCT. • Similar survival after matched unrelated and related donor HSCT for AML or MDS reflects lower NRM but higher relapse risks in the latter. Abstract Increasing donor–recipient HLA disparity is associated with negative outcomes of allogeneic hematopoietic stem cell transplantation (HSCT), but its comparative relevance amid non-HLA donor characteristics is not well established. We addressed this question in 3215 HSCTs performed between 2005 and 2013 in Germany for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Donors were HLA-matched related (MRD; n = 872) or unrelated (10/10 MUD, n = 1553) or HLA-mismatched unrelated (<10/10 MMUD, n = 790). Overall survival (OS) was similar after MRD compared with 10/10 MUD HSCT, reflecting opposing hazards of relapse (hazard ratio [HR], 1.32; P <.002) and nonrelapse mortality (HR,.63; P <.001). After UD HSCT, increasing HLA disparity was associated with inferior OS (HR, 1.21 [ P <.02] and HR, 1.57 [ P <.001] for 9/10 and ≤8/10 MMUD, respectively, compared with 10/10 MUD). Among non-HLA donor characteristics, age, sex mismatching (male recipient–female donor), and cytomegalovirus (CMV) mismatching (positive recipient–negative donor) impacted OS. Multivariate subgroup analysis showed that OS was similar after HSCT from the youngest 9/10 MMUD (<30 years) compared with the oldest 10/10 MUD (>40 years) (HR, 1.18; P =.25) and also in male patients transplanted from female 10/10 MUD compared with male 9/10 MMUD (HR,.89; P =.46). In contrast, OS of CMV-positive patients tended to be better with CMV-negative 10/10 MUDs compared with CMV-positive 9/10 MMUDs (HR, 1.31; P =.04). Because of low patient numbers in subgroups, definite conclusions and establishment of a hierarchy among HLA matching and non-HLA donor characteristics could not be made. Our data suggest that the impact of donor age and sex mismatch but not CMV mismatch on outcome of allogeneic HSCT may be comparable with that of single HLA disparity. [ABSTRACT FROM AUTHOR]

Chronic graft versus host disease (cGvHD) is the most common cause of late morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). We retrospectively evaluated the impact of NIH classification on outcome of patients at our center. Primary endpoint was overall survival at 5 years. Two hundred one patients with cGVHD according to NIH were included. Platelets <100,000/μl on day of diagnosis of cGvHD (HR 2.97, 95 % CI 1.7-5.3, p < 0.001), female donor (HR 1.78, 95 % CI 1.0-3.2, p = 0.05), and reduced intensity conditioning (HR 1.95, 95 % CI 1.0-3.8, p = 0.05) impacted overall survival. Non-relapse mortality (NRM) was higher for patients with low vs. high platelets: 26 % (95 % CI 14-40) vs. 6 % (95 % CI 2-10), p < 0.001, and tended to be higher for female vs. male donor: 14 % (95 % CI 7-23) vs. 7 % (95 % CI 3-13), p = 0.08. Relapse tended to be higher for recipients of reduced intensity conditioning (RIC) vs. myeloablative conditioning (MAC): 33 % (95 % CI 23-43) vs. 20 % (95 % CI 10-31), p = 0.06. After excluding patients with myeloma and lymphoma, IgG serum levels at diagnosis of cGvHD of 122 patients were correlated with survival. IgG levels above normal were associated with worse 2-year overall survival (OS), p = 0.04, compared to normal or low IgG levels. Platelet count at diagnosis remains the most valid prognostic factor for survival of patients with cGvHD even in the era of NIH grading. High IgG level at diagnosis of cGVHD represents a potential negative prognostic parameter that deserves further investigation. [ABSTRACT FROM AUTHOR]

Abstract: To assess current clinical practice in diagnosis and treatment of acute graft-versus-host disease (aGVHD), we performed a survey among German, Austrian, and Swiss allogeneic hematopoietic stem cell transplantation (allo-HSCT) centers. Thirty-four of 72 contacted centers (47%) completed both the diagnostic and therapeutic sections of the survey, representing 65% of allo-HSCT activity within the participating countries in 2011. Three pediatric centers answered as requested only the diagnostic part of the survey. In the presence of diarrhea and decreased oral intake after engraftment, only 4 centers (12%) do not perform any endoscopy before the start of immunosuppressive treatment. In case of a skin rash with the differential diagnosis of drug reaction, only 12 centers (35%) perform a skin biopsy up front, whereas 19 do so after failure of systemic steroids. In the presence of rapidly increasing cholestasis occurring without any other signs of aGVHD, 11 centers (32%) perform a liver biopsy up front and 14 only after failure of steroid treatment, whereas 9 centers do not perform a liver biopsy at all. Twenty centers (59%) use a percutaneous approach, 12 a transvenous approach, and 1 mini-laparoscopy for liver biopsies. First-line treatment of cutaneous aGVHD stage 1 consists of topical treatment alone in 17 of 31 responding centers (61%), whereas isolated cutaneous aGVHD stage III is treated with systemic steroids (prednisolone below 0.5 mg/kg/day n = 2, 0.5 to 1.0 mg/kg/day n = 10, above 1.0 to 2.5 mg/kg/day n = 19) without or with topical agents (steroids n = 10; calcineurin inhibitors n = 3). In gastrointestinal manifestations of aGVHD, 9 centers (29%) add topical to systemic steroids, and 3 consider topical steroids as the only treatment for mild gastrointestinal and cutaneous aGVHD. The choice of agent for second-line treatment as well as the sequence of administration are extremely heterogeneous, most likely due to a lack of convincing data published. Most frequently used are mycophenolate mofetil (n = 14) and extracorporeal photopheresis (n = 10). Our survey also demonstrates that clinicians chose salvage therapies for steroid-refractory aGVHD based on their centers'' own clinical experience. [Copyright &y& Elsevier]

Introduction: Chimeric antigen receptor positive T cell (CAR-T cell) treatment became standard therapy for relapsed or refractory hematologic malignancies, such as non-Hodgkin's lymphoma and multiple myeloma. Owing to the rapidly progressing field of CAR-T cell therapy and the lack of generally accepted treatment guidelines, we hypothesized significant differences between centers in the prevention, diagnosis, and management of short- and long-term complications. Methods: To capture the current CAR-T cell management among German centers to determine the medical need and specific areas for future clinical research, the DAG-HSZT (Deutsche Arbeitsgemeinschaft für Hämatopoetische Stammzelltransplantation und Zelluläre Therapie; German Working Group for Hematopoietic Stem Cell Transplantation and Cellular Therapy) performed a survey among 26 German CAR-T cell centers. Results: We received answers from 17 centers (65%). The survey documents the relevance of evidence in the CAR-T cell field with a homogeneity of practice in areas with existing clinical evidence. In contrast, in areas with no – or low quality – clinical evidence, we identified significant variety in management in between the centers: management of cytokine release syndrome, immune effector cell-related neurotoxicity syndrome, IgG substitution, autologous stem cell backups, anti-infective prophylaxis, and vaccinations. Conclusion: The results indicate the urgent need for better harmonization of supportive care in CAR-T cell therapies including clinical research to improve clinical outcome. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to create a simple and reliable tool, the CORE HCT score, to predict the chances of non-relapse mortality (NRM) and overall survival (OS) after allogeneic hematopoietic stem cell transplantation (allo-HCT). Using data from 1120 adult patients who had undergone this procedure at our center between 2013 and 2020, we identified specific patient factors affecting NRM: serum albumin, serum creatinine, serum C-reactive protein, heart and lung function, and age. Factors were weighted according to their impact on NRM. The resulting CORE HCT score grouped patients into low-, medium-, and high-risk categories, showing its effectiveness across different conditions and donor types. Notably, compared with the HCT Comorbidity Index (HCT-CI), the CORE HCT score performed better in predicting NRM and OS. The findings were validated in two independent cohorts, which supports the utility of the CORE HCT score in guiding risk assessment for allo-HCT in adult patients with malignant diseases. We aimed to develop a concise objectifiable risk evaluation (CORE) tool for predicting non-relapse mortality (NRM) and overall survival (OS) after allogeneic hematopoietic stem cell transplantation (allo-HCT). A total of 1120 adult patients who had undergone allo-HCT at our center between 2013 and 2020 were divided into training, first, and second validation cohorts. Objectifiable, patient-related factors impacting NRM in univariate and multivariate analyses were: serum albumin, serum creatinine, serum C-reactive protein (CRP), heart function (LVEF), lung function (VC, FEV1), and patient age. Hazard ratios were assigned points (0–3) based on their impact on NRM and summed to the individual CORE HCT score. The CORE HCT score stratified patients into three distinct low-, intermediate-, and high-risk groups with two-year NRM rates of 9%, 22%, and 46%, respectively, and OS rates of 73%, 55%, and 35%, respectively (p < 0.001). These findings were confirmed in a first and a second recently treated validation cohort. Importantly, the CORE HCT score remained informative across various conditioning intensities, disease-specific subgroups, and donor types, but did not impact relapse incidence. A comparison of CORE HCT vs. HCT Comorbidity Index (HCT-CI) in the second validation cohort revealed better performance of the CORE HCT score with c-statistics for NRM and OS of 0.666 (SE 0.05, p = 0.001) and 0.675 (SE 0.039, p < 0.001) vs. 0.431 (SE 0.057, p = 0.223) and 0.535 (SE 0.042, p = 0.411), respectively. The CORE HCT score is a concise and objectifiable risk evaluation tool for adult patients undergoing allo-HCT for malignant disease. External multicenter validation is underway. [ABSTRACT FROM AUTHOR]

Background: Patients with steroid-refractory acute graft-versus-host disease (aGvHD) not tolerating/responding to ruxolitinib (RR-aGvHD) have a dismal prognosis. Methods: We retrospectively assessed real-world outcomes of RR-aGvHD treated with the random-donor allogeneic MSC preparation MSC-FFM, available via Hospital Exemption in Germany. MSC-FFM is provided as frozen cell dispersion for administration as i.v. infusion immediately after thawing, at a recommended dose of 1–2 million MSCs/kg body weight in 4 once-weekly doses. 156 patients, 33 thereof children, received MSC-FFM; 5% had Grade II, 40% had Grade III, and 54% had Grade IV aGvHD. Median (range) number of prior therapies was 4 (1–10) in adults and 7 (2–11) in children. Results: The safety profile of MSC-FFM was consistent with previous reports for MSC therapies in general and MSC-FFM specifically. The overall response rate at Day 28 was 46% (95% confidence interval [CI] 36–55%) in adults and 64% (45–80%) in children; most responses were durable. Probability of overall survival at 6, 12 and 24 months was 47% (38–56%), 35% (27–44%) and 30% (22–39%) for adults, and 59% (40–74%), 42% (24–58%) and 35% (19–53%) for children, respectively (whole cohort: median OS 5.8 months). Conclusion: A recent real-world analysis of outcomes for 64 adult RR-aGvHD patients not treated with MSCs reports survival of 20%, 16% and 10% beyond 6, 12 and 24 months, respectively (median 28 days). Our data thus suggest effectiveness of MSC-FFM in RR-aGvHD. [ABSTRACT FROM AUTHOR]

Pre‐transplant minimal residual disease (MRD) impacts negatively on post‐transplant relapse risk in acute myeloid leukemia (AML). Therapeutic drug monitoring by calculating area under the curve (AUC) was developed to optimize busulfan (Bu) exposure. Here, we compared post‐transplant outcomes after individualized versus fixed busulfan dosage in intermediate‐risk AML who achieved CR prior to allograft focusing on pre‐transplant flow‐MRD. Eighty‐seven patients (median, 56 years) with intermediate‐risk AML and pre‐transplant flow‐MRD ("different from normal") were included. Thirty‐two patients received individualized busulfan; 54 fixed dosages. Individualized dosage was adjusted in 25/32 patients: increased, n = 18/25 (72%); decreased: n = 7/25 (28%). After median follow‐up of 27 months, we observed lower 3‐year relapses (6%, 2%–19% vs. 35%, 23%–49% p = 0.02), improved 3‐year leukemia‐free survival (LFS) (78%, 54%–91% vs. 55%, 40%–70% p = 0.009) and − overall survival (OS) (82%, 60%–93% vs. 69%, 54%–81% p = 0.05) after individualized compared to fixed Bu. Non‐relapsed mortality (NRM) and acute graft versus host disease (GvHD) were not different. In multivariate analysis, fixed Bu showed unfavorable impact on OS (hazard ratio [HR] 4.6, p = 0.044), LFS (HR 3.6, p = 0.018) and relapses (HR 3.6, p = 0.033). Fixed Bu also had unfavorable impact on LFS (3.6, 1.1–12.6, p = 0.041) in pre‐transplant MRD‐positive patients. Individualized, AUC‐based, busulfan is associated with lower relapses in intermediate‐risk AML patients allografted in CR and may overcome pre‐transplant MRD‐positivity. [ABSTRACT FROM AUTHOR]

Chronic graft-versus-host disease (cGVHD) after allogeneic hematopoietic stem cell transplantation is still associated with significant morbidity and mortality. First-line treatment of cGVHD is based on steroids of 1 mg/kg/day of prednisone. The role of calcineurin inhibitors remains controversial, especially in patients with low risk for mortality (normal platelets counts), whereas patients with low platelets at diagnosis and/or high risk for steroid toxicity may be treated upfront with the combination of prednisone and a calcineurin inhibitor. Additional systemic immunosuppressive agents, like thalidomide, mycophenolic acid, and azathioprine, failed to improve treatment results in the primary treatment of cGVHD and are in part associated with higher morbidity, and in the case of azathioprine, with higher mortality. Despite advances in diagnosis of cGVHD as well as supportive care, half of the patients fail to achieve a long-lasting response to first-line treatment, and infectious morbidity continues to be significant. Therefore, immunomodulatory interventions with low infectious morbidity and mortality such as photopheresis need urgent evaluation in clinical trials. Beside systemic immunosuppression, the use of topical immunosuppressive interventions may improve local response rates and may be used as the only treatment in mild localized organ manifestations of cGVHD. [Copyright &y& Elsevier]

Objectives: During allogeneic hematopoietic stem cell transplantation (allo‐SCT), infections significantly contribute to morbidity and mortality. A monocentric prospective analysis was performed to assess epidemiology, risk factors, and outcomes of infections during the peri‐transplant period. Methods: Data were recorded prospectively using a predefined questionnaire. Results: In 2015, 163 consecutive patients, 37.4% female, median age 59 (range 18‐79) years received 166 allo‐SCT. Median duration of leukopenia <109/L was 14.5 days (range 4‐43 days). Fever of unknown origin (FUO) occurred in 118/166 patients (71.1%). Severe sepsis developed in 95, and septic shock developed in 26 patients. Intensive diagnostic workup helped to identify causative microorganisms only in a small number of infectious courses. All but 13 patients needed antibiotic therapy, each according to the standard operating procedures of the department. Cumulative incidence of death by infection after 1 year was 16.6% (95% CI: 11.3‐22.7). The only risk factor for FUO in neutropenia was duration of neutropenia

The major reason for treatment failure after allografting in multiple myeloma (MM) is relapse. Donor lymphocyte infusions (DLIs) are considered a valuable post-transplant strategy mainly for relapsed patients but using them to prevent relapse in MM has been reported rarely. In the present study, we examined the efficacy of prophylactic DLIs after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in myeloma patients with a long-term follow-up of more than 5 years. A total of 61 patients with MM who did not relapse or develop disease progression after allo-HSCT were treated with prophylactic DLI in an escalating fashion (overall 132 DLI procedures) to deepen remission status and prevent relapse. Overall response rate to DLI was 77%. Thirty-three patients (54%) upgraded their remission status, 41 patients (67%) achieved or maintained complete remission, and 26% achieved a molecular remission. Incidence of acute graft-versus-host disease (GVHD) grade II to IV was 33% and no DLI-related mortality was noted. After a median follow-up of 68.7 months from first DLI the estimated 8-year progression-free survival (PFS), and overall survival (OS) in a landmark analysis was 43% (95% confidence interval [CI], 28% to 57%) and 67% (95% CI, 53% to 82%), respectively, with best outcome for patients who acquired molecular remission (8-year PFS was 62% and 8-year OS was 83%). Prophylactic escalating DLI in a selected cohort of MM patients to prevent relapse after allograft resulted in a low incidence of severe GVHD and encouraging long-term results, especially if molecular remission is achieved. [ABSTRACT FROM AUTHOR]

Molecular genetics may influence outcome for patients with myelofibrosis. To determine the impact of molecular genetics on outcome after allogeneic stem cell transplantation, we screened 169 patients with primary myelofibrosis (n = 110), post-essential thrombocythemia/polycythemia vera myelofibrosis (n = 46), and myelofibrosis in transformation (n = 13) for mutations in 16 frequently mutated genes. The most frequent mutation was JAK2V617F (n = 101), followed by ASXL1 (n = 49), calreticulin (n = 34), SRSF2 (n = 16), TET2 (n = 10), U2AF1 (n = 11), EZH2 (n = 7), MPL (n = 6), IDH2 (n = 5), IDH1 (n = 4), and CBL (n = 1). The cumulative incidence of nonrelapse mortality (NRM) at 1 year was 21% and of relapse at 5 years 25%. The 5-year rates progression-free (PFS) and overall survival (OS) were and 56%, respectively. In a multivariate analysis CALR mutation was an independent factor for lower NRM (HR, .415; P  = .05), improved PFS (HR, .393; P  = .01), and OS (HR, .448; P  = .03). ASXL1 and IDH2 mutations were independent risk factors for lower PFS (HR, 1.53 [ P  = .008], and HR, 5.451 [ P  = .002], respectively), whereas no impact was observed for “triple negative” patients. Molecular genetics, especially CALR , IDH2 , and ASXL1 mutations, may thus be useful to predict outcome independently from known clinical risk factors after allogeneic stem cell transplantation for myelofibrosis. [ABSTRACT FROM AUTHOR]

Allogeneic hematopoietic stem cell transplantation (allo- HSCT) is a curative treatment option for myelodysplastic syndromes ( MDS). Little is known about the prognostic impact of mutations, for example, in TP53 specifically after allo- HSCT. We here describe the prognostic impact of mutations in a panel of 19 genes analyzed by amplicon-based next-generation-sequencing in a uniformly treated patient cohort. Sixty-two patients with a median age of 61 yr suffered from MDS with 0-20% bone marrow blasts. International Prognostic Score was intermediate 1 (15%) and higher (79%). Conditioning uniformly was performed using a sequential approach in which FLAMSA chemotherapy was followed by Busulfan-based conditioning. Patients mostly were transplanted from an unrelated donor (77%), and 36% of patients received a graft from a mismatched donor. Median number of mutations was 2 (range 0-6). RUNX1, GATA2, TET2, and CEBPA were the genes most frequently found mutated. TP53, a factor previously reported to confer adverse prognostic impact after allogeneic stem cell transplantation, was mutated in samples from eight patients, one of which showed a silent mutation. With an estimated 5-yr overall/disease-free survival of 48 ± 7%/41 ± 7%, none of the mutations analyzed showed a prognostic impact in this analysis of the largest uniformly treated cohort thus far. This especially holds true for patients with a mutation in TP53. [ABSTRACT FROM AUTHOR]

Allogeneic hematopoietic stem cell transplantation remains the sole curative option for myelofibrosis. Many transplantation recipients receive a reduced-intensity conditioning (RIC) regimen owing to age or comorbidities; however, there is little published evidence to guide the choice of RIC regimen. In this study, we compared outcomes in patients who received 1 of 2 frequently used RIC regimens for patients with myelofibrosis: fludarabine-busulfan (FB) and fludarabine-melphalan (FM). A total of 160 patients underwent a RIC allograft procedure (FB group, n = 105; FM group, n = 55). We have developed a complex statistical model involving weighting and adjustment to permit comparison between these 2 groups. After weighting, the incidence of acute graft-versus-host disease (GVHD) was 62% in the FM group and 31% in the FB group ( P = .001), and the corresponding incidence of chronic GVHD was 49% and 53%, respectively. The 7-year progression-free survival was were 52% in the FM group versus 33% in the FB group, and the 7-year overall survival rate 52% in the FM group versus 59% in the FB group. Nonrelapse mortality (NRM) was 43% in the FM group and 31% in the FB group. Multivariable analyses revealed no significant differences in PFS between the 2 groups; however, the relapse rate was significantly lower in the FM group (hazard ratio, 9.21; P = .008), whereas a trend toward reduced NRM was seen in the FB group (hazard ratio, 0.51; P = .068). In conclusion, both regimens appear to be efficient in mediating disease control and can be used to successfully condition patients with myelofibrosis. The FM regimen appears to induce more NRM than the FB regimen, but with augmented control of disease, leading to comparable overall survival rates for both regimens. [ABSTRACT FROM AUTHOR]

Acute graft-versus-host disease (GVHD) remains a leading cause of morbidity and nonrelapse mortality after allogeneic hematopoietic cell transplantation. The clinical staging of GVHD varies greatly between transplant centers and is frequently not agreed on by independent reviewers. The lack of standardized approaches to handle common sources of discrepancy in GVHD grading likely contributes to why promising GVHD treatments reported from single centers have failed to show benefit in randomized multicenter clinical trials. We developed guidelines through international expert consensus opinion to standardize the diagnosis and clinical staging of GVHD for use in a large international GVHD research consortium. During the first year of use, the guidance followed discussion of complex clinical phenotypes by experienced transplant physicians and data managers. These guidelines increase the uniformity of GVHD symptom capture, which may improve the reproducibility of GVHD clinical trials after further prospective validation. [ABSTRACT FROM AUTHOR]

Toxoplasmosis and infections by other opportunistic agents such as Pneumocystis jirovecii constitute life-threatening risks for patients after allogeneic hematopoietic stem cell transplantation. Trimethoprim/sulfamethoxazole (TMP-SMX) has been well established for post-transplant toxoplasmosis and pneumocystis prophylaxis, but treatment may be limited due to toxicity. We explored atovaquone as an alternative and compared it with TMP-SMX regarding toxicity and efficacy during the first 100 days after transplantation in 155 consecutive adult stem cell recipients. Eight patients with a prior history of TMP-SMX intolerance received atovaquone as first-line prophylaxis. TMP-SMX was used for 141 patients as first-line strategy, but 13 patients (9.2%) were later switched to atovaquone due to TMP-SMX toxicity or gastrointestinal symptoms. No active toxoplasmosis or active P. jirovecii infection developed under continued prophylaxis with either TMP-SMX or atovaquone. However, for reasons of TMP-SMX and/or atovaquone toxicity, 7 patients were unable to tolerate any efficacious toxoplasmosis prophylaxis and therefore obtained inhalative pentamidine as P. jirovecii prophylaxis but no toxoplasmosis prophylaxis. Importantly, 2 of these patients developed severe toxoplasmosis. In summary, atovaquone appears as a valid alternative for at least some post-transplant patients who cannot tolerate TMP-SMX. This should be further confirmed by multicenter trials. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Considering the high relapse rates of AML after allogeneic hematopoietic stem cell transplant, research aims to improve post-transplant surveillance. To determine the value of peripheral blood (PB) for post-transplant minimal residual disease monitoring, we compared 38 PB and bone marrow (BM) sample pairs in 25 stem cell recipients with NPM1-mutated AML (12 males, 13 females, ages 21-73 years). NPM1A mutation levels and chimerism ratios were determined in non-separated BM/PB. We observed congruent results in 28/38 (74%). In 14/38 sample pairs (37%), BM and PB were negative for the NPM1A mutation. Fourteen sample pairs were positive in BM and PB, albeit at higher mutation levels in the BM in 11 cases (4- to 278-fold). Results were discordant in 10 cases (26%), with weakly positive mutation levels in the BM but negative levels in the PB. Cases with ≥0.2% NPM1A mutation level in BM were always positive in PB. Chimerism was concordant in BM and PB in 21/34 (62%) of sample pairs. In conclusion, MRD monitoring with qPCR for the NPM1 mutation and chimerism from non-separated PB contributes to surveillance in patients with AML in the post-transplant period, but even with highly sensitive qPCR there is a risk of failure to detect the mutation in PB. [ABSTRACT FROM AUTHOR]

Simple Summary: Currently, the only curative therapy in myelofibrosis is allogeneic hematopoietic stem cell transplantation. Donor lymphocyte infusion and second stem cell transplantation are the two main treatment options for myelofibrosis patients who relapse after the first transplantation. The optimal conditioning regimen for the second transplantation in myelofibrosis patients is not well defined. Our study aimed to address this question and showed that treosulfan-based conditioning for second allograft in relapsed myelofibrosis patients resulted in longtime freedom from disease in about 50% of the patients. This data supports the second allogeneic hematopoietic stem cell transplantation with a less toxic treosulfan-based conditioning regimen that is effective in relapsed, donor lymphocyte infusion resistant myelofibrosis patients with long term low transplant-related mortality and relapse rates. Relapse after allogeneic hematopoietic stem cell transplantation (AHSCT) in myelofibrosis (MF) patients remains as a significant issue despite advances in transplantation procedures and significant prolongation in survival. Second AHSCT is a potential treatment option but associated with high treatment-related mortality and novel less toxic conditioning regimens are needed. In 33 MF patients with relapse after AHSCT and failure to donor lymphocyte infusion (DLI) we investigated treosulfan (36–42 g/m2) in combination with fludarabine and anti-thymocyte globulin (ATG) as conditioning regimen for a second AHSCT with matched related (n = 2), unrelated (n = 23), or mismatched unrelated (n = 8) donors. All patients achieved leukocyte engraftment after a median of 11 days, and 56 ± 13% experienced acute GVHD grade II–IV at day 100. The therapy-related mortality at day 100 and at 3 years was 16% and 31%, respectively. The cumulative incidence of relapse at 5 years was 16%, resulting in a 5-year disease-free and overall survival of 45% and 47%, respectively. Treosulfan-based conditioning for second allograft in relapsed MF patients resulted in about 50% of the patients in long-term freedom from disease. [ABSTRACT FROM AUTHOR]