Achieving stringent CR is essential before reduced-intensity conditioning allogeneic hematopoietic cell transplantation in AML

Measurable residual disease (MRD) status before allogeneic hematopoietic cell transplantation impact on secondary acute myeloid leukemia outcome. A Study from the Acute Leukemia Working Party (ALWP) of the European society for Blood and Marrow Transplantation (EBMT)

Measurable residual disease (MRD) assessment before allogeneic hematopoietic cell transplantation (HCT) may help physicians to identify a subgroup of patients at high risk of relapse for de novo acute myeloid leukemia (AML) but its relevance among patients affected by secondary AML (sAML) is still unknown. We assessed the impact of MRD among 318 adult patients with sAML who received an allogeneic HCT in first complete remission. At the time of HCT, a total of 208 (65%) patients achieved MRD negativity, while 110 (35%) had positive MRD. 2-year overall survival (OS) was 58.8 % (95% CI 52.2-64.9) with leukemia-free survival (LFS) of 50.0 % (95% CI 43.7-56.1), relapse incidence of 34.2% (95% CI 28.4-40.1) and non-relapse mortality (NRM) of 23.3 % (95% CI 19-27.7) for the entire cohort. In multivariate analysis, HCT recipients with KPS ≥ 90 experienced less disease recurrence (HR 0.61, 95% CI 0.4-0.94) with better LFS (HR 0.63, 95% CI 0.44-0.89) and OS (HR 0.58, 95% CI 0.39-0.86). There were no differences in major clinical endpoints between patients with MRD-positive and MRD-negative status at the time of HCT. Pre-transplantation assessment of MRD was not informative on post-HCT outcomes in this retrospective registry-based analysis among patients affected by sAML.

Increased overall and bacterial infections following myeloablative allogeneic HCT for patients with AML in CR1

Presumably, reduced-intensity/nonmyeloablative conditioning (RIC/NMA) for allogeneic hematopoietic cell transplantation (alloHCT) results in reduced infections compared with myeloablative conditioning (MAC) regimens; however, published evidence is limited. In this Center for International Blood and Marrow Transplant Research study, 1755 patients (aged ≥40 years) with acute myeloid leukemia in first complete remission were evaluated for infections occurring within 100 days after T-cell replete alloHCT. Patients receiving RIC/NMA (n = 777) compared with those receiving MAC (n = 978) were older and underwent transplantation more recently; however, the groups were similar regarding Karnofsky performance score, HCT-comorbidity index, and cytogenetic risk. One or more infections occurred in 1045 (59.5%) patients (MAC, 595 [61%]; RIC/NMA, 450 [58%]; P = .21) by day 100. The median time to initial infection after MAC conditioning occurred earlier (MAC, 15 days [range, <1-99 days]; RIC/NMA, 21 days [range, <1-100 days]; P < .001). Patients receiving MAC were more likely to experience at least 1 bacterial infection by day 100 (MAC, 46% [95% confidence interval (CI), 43-49]; RIC/NMA, 37% [95% CI, 34-41]; P = .0004), whereas at least a single viral infection was more prevalent in the RIC/NMA cohort (MAC, 34% [95% CI, 31-37]; RIC/NMA, 39% [95% CI, 36-42]; P = .046). MAC remained a risk factor for bacterial infections in multivariable analysis (relative risk, 1.44; 95% CI, 1.23-1.67; P < .0001). Moreover, the rate of any infection per patient-days at risk in the first 100 days (infection density) after alloHCT was greater for the MAC cohort (1.21; 95% CI, 1.11-1.32; P < .0001). RIC/NMA was associated with reduced infections, especially bacterial infections, in the first 100 days after alloHCT.

Evaluation of induction chemotherapies after hypomethylating agent failure in myelodysplastic syndromes and acute myeloid leukemia

Hypomethylating agent (HMA) failure in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) carries a poor prognosis with limited treatment options. Although intensive, remission induction chemotherapy is often used subsequently, in particular to bridge to allogeneic transplantation, it is not clear whether an advantage exists for any particular regimen. Based on an international collaboration, we retrospectively analyzed induction response rate and survival in 366 patients after HMA failure. Patients received 7+3, intermediate- to high-dose cytarabine (IDAC), or purine nucleoside analog-based regimens. For the MDS cohort (n = 307), the overall response rate (ORR) was 41%; median overall survival (OS) was 10.8 months, and 40% of responding patients bridged to allogeneic stem cell transplant (allo-SCT). For the AML cohort (n = 59), the ORR was 32%, OS 6 months, and 42% of responding patients bridged to allo-SCT. Prognostic factors for response in MDS included adverse cytogenetics (odds ratio [OR], 0.46, P = .01), age ≥65 years (OR, 0.47; P < .01), and use of IDAC (OR, 2.91, P = .01). Shorter survival was associated with adverse cytogenetics (hazard ratio [HR], 1.43; P = .06). In the AML cohort, OS was decreased by disease progression at time of HMA failure (HR, 2.66; P = .02) and prolonged with use of an anthracycline-containing regimen (HR, 0.37; P = .01). In conclusion, intensive chemotherapy after HMA failure may be a reasonable treatment option for selected patients as a bridge to allogeneic transplantation and should be considered a potential platform for future investigations.

Reduced-Intensity Conditioning Followed by Related and Unrelated Allografts for Hematologic Malignancies: Expanded Analysis and Long-Term Follow-Up

Reduced-intensity conditioning (RIC) extends the curative potential of allogeneic hematopoietic cell transplantation (HCT) to patients with hematologic malignancies unable to withstand myeloablative conditioning. We prospectively analyzed the outcomes of 292 consecutive patients, median age 58 years (range, 19 to 75) with hematologic malignancies treated with a uniform RIC regimen of cyclophosphamide, fludarabine, and total body irradiation (200 cGy) with or without antithymocyte globulin and cyclosporine and mycophenolate mofetil graft-versus-host disease (GVHD) prophylaxis followed by allogeneic HCT at the University of Minnesota from 2002 to 6. Probability of 5-year overall survival was 78% for patients with indolent non-Hodgkin lymphoma, 53% for chronic myelogenous leukemia, 55% for Hodgkin lymphoma, 40% for acute myelogenous leukemia, 37% for myelodysplastic syndrome, 29% for myeloma, and 14% for myeloproliferative neoplasms. Corresponding outcomes for relapse were 0%, 13%, 53%, 37%, 39%, 75%, and 29%, respectively. Disease risk index (DRI) predicted both survival and relapse with superior survival (64%) and lowest relapse (16%) in those with low risk score compared with 24% survival and 57% relapse in those with high/very-high risk scores. Recipient cytomegalovirus (CMV)-positive serostatus was protective from relapse with the lowest rates in those also receiving a CMV-positive donor graft (29%). The cumulative incidence of 2-year nonrelapse mortality was 26% and was lowest in those receiving a matched sibling graft at 21%, with low (21%) or intermediate (18%) HCT-specific comorbidity index, and was similar across age groups. The incidence of grades II to IV acute GVHD was 43% and grades III to IV 27%; the highest rates were found in those receiving an unrelated donor (URD) peripheral blood stem cell (PBSC) graft, at 50%. Chronic GVHD at 1 year was 36%. Future approaches incorporating alternative GVHD prophylaxis, particularly for URD PBSC grafts, and targeted post-transplant antineoplastic therapies for those with high DRI are indicated to improve these outcomes.

Effects of post-remission chemotherapy before allo-HSCT for acute myeloid leukemia during first complete remission: a meta-analysis

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is most frequently used to treat acute myeloid leukemia (AML). Whether patients should routinely receive consolidation chemotherapy before proceeding to transplant after achieving first complete remission (CR1) has been a subject of debate. We performed a systematic review and meta-analysis of studies examining the impact of post-remission chemotherapy before allo-HSCT in patients with AML in CR1. Six studies including 1659 patients were included in the meta-analysis. The pooled hazard ratio (HR) for overall survival was 0.9 (95% confidence interval [CI] 0.77-1.05, P = 0.182), and the pooled HR for leukemia-free survival was 0.87 (95% CI 0.75-1.0, P = 0.07). No survival advantage was observed for post-remission chemotherapy before reduced-intensity conditioning or myeloablative conditioning (MAC) allo-HSCT for AML in CR1. The pooled relative risk for relapse incidence (RI) was 1.02 (95% CI 0.82-1.28, P = 0.834). Post-remission chemotherapy before allo-HSCT did not significantly affect the RI in patients with AML in CR1. The analyses revealed no significant benefit of post-remission consolidation chemotherapy in patients who received allo-HSCT. We recommend proceeding to allo-HSCT as soon as CR1 is attained.

First-in-human phase 1 clinical study of the IL-15 superagonist complex ALT-803 to treat relapse after transplantation

New therapies for patients with hematologic malignancies who relapse after allogeneic hematopoietic cell transplantation (allo-HCT) are needed. Interleukin 15 (IL-15) is a cytokine that stimulates CD8+ T-cell and natural killer (NK) cell antitumor responses, and we hypothesized this cytokine may augment antileukemia/antilymphoma immunity in vivo. To test this, we performed a first-in-human multicenter phase 1 trial of the IL-15 superagonist complex ALT-803 in patients who relapsed >60 days after allo-HCT. ALT-803 was administered to 33 patients via the IV or subcutaneous (SQ) routes once weekly for 4 doses (dose levels of 1, 3, 6, and 10 μg/kg). ALT-803 was well tolerated, and no dose-limiting toxicities or treatment-emergent graft-versus-host disease requiring systemic therapy was observed in this clinical setting. Adverse events following IV administration included constitutional symptoms temporally related to increased serum IL-6 and interferon-γ. To mitigate these effects, the SQ route was tested. SQ delivery resulted in self-limited injection site rashes infiltrated with lymphocytes without acute constitutional symptoms. Pharmacokinetic analysis revealed prolonged (>96 hour) serum concentrations following SQ, but not IV, injection. ALT-803 stimulated the activation, proliferation, and expansion of NK cells and CD8+ T cells without increasing regulatory T cells. Responses were observed in 19% of evaluable patients, including 1 complete remission lasting 7 months. Thus, ALT-803 is a safe, well-tolerated agent that significantly increased NK and CD8+ T cell numbers and function. This immunostimulatory IL-15 superagonist warrants further investigation to augment antitumor immunity alone and combined with other immunotherapies. This trial was registered at www.clinicaltrials.gov as #NCT01885897.

Minimal residual disease by either flow cytometry or cytogenetics prior to an allogeneic hematopoietic stem cell transplant is associated with poor outcome in acute myeloid leukemia

Relapsed acute myeloid leukemia (AML) is a significant challenge after allogeneic hematopoietic cell transplant (HCT). Multiparameter flow cytometry (MFC), conventional cytogenetics (CG), and fluorescence in situ hybridization (FISH) are routinely performed on bone marrow specimens prior to HCT to assess disease status. We questioned the extent by which pre-HCT evidence of minimal residual disease (MRD) detected by these standard assays, corresponded with post-HCT relapse. We conducted a single center, retrospective study of 166 AML patients who underwent HCT. Thirty-eight of one hundred sixty-six (23%) patients in complete remission (CR) or CR with incomplete count recovery (CRi) had MRD detectable by MFC, CG, or FISH. MRD was more frequently seen in patients with poor risk karyotype at diagnosis (P = 0.011). MRD-negative patients (MRD^neg) had significantly longer overall survival (OS) and relapse-free survival than patients who were MRD positive (MRD^pos) (P = 0.002 and 0.013, respectively). In patients with MRD^pos prior to HCT, the presence of acute graft vs. host disease (GVHD) (grade ≥ 2) or chronic GVHD significantly improved progression free survival (PFS) (hazard ratio (HR) = 0.053 (95% confidence interval (CI): 0.01-0.279), P = 0.0005) and OS (HR = 0.211 (95% CI: 0.081-0.547), P = 0.0014).

History of consolidation is prognostic in acute myeloid leukemia patients undergoing allogeneic hematopoietic cell transplantation in minimal residual disease-negative first complete remission

BACKGROUND

Prognostic factors among acute myeloid leukemia (AML) patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) in minimal residual disease (MRD)-negative first complete remission (CR1) are unknown. We retrospectively attempted to answer the following question: In AML patients undergoing allo-HCT in MRD-negative CR1, does a history of prior consolidation provide additional prognostic information?

METHODS

The inclusion criteria were: (i) Age > 18 years, (ii) AML in CR1 after 1-2 cycles of intensive induction chemotherapy, with or without consolidation, (iii) Allo-HCT between 1/2003 and 4/2016 at our institution, (iv) Available standard-sensitivity 4-color flow cytometry results from a bone marrow aspiration at diagnosis and after completion of all previous chemotherapy within one month prior to HCT, (v) Flow cytometry-based MRD-negative status at the time of HCT.

RESULTS

A history of prior consolidation was associated with favorable overall survival (Hazard Ratio [95% Confidence Interval]: 0.59 [0.35-0.99], P = .046), relapse-free survival (0.60 [0.37-0.96], P = .036), and relapse (0.50 [0.27-0.92], P = .025). Analysis of potential sources of bias was unrevealing.

CONCLUSIONS

In AML patients undergoing allo-HCT in MRD-negative CR1, a history of prior consolidation was associated with favorable outcomes. If the path to pre-HCT MRD negativity includes consolidation, it may identify patients with improved prognosis following HCT in MRD-negative state. These results warrant validation in larger cohorts.

Allogeneic Hematopoietic Cell Transplantation for Older Patients: Prognosis Determined by Disease Risk Index

The treatment of elderly patients with advanced hematological malignancies has expanded to include reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (alloHCT) as a potentially curative option. We studied the association between Disease Risk Index (DRI) and clinical outcomes of 196 elderly patients (median age, 64.8; range, 60 to 75 years) with hematological malignancies receiving RIC alloHCT (2000 to 2014). Donors were related and unrelated adults (n = 100, 51.1%) or umbilical cord blood (n = 96, 48.9%). DRI classified 12 patients (6.1%) as low risk (LR), 146 patients (74.5%) as intermediate risk (IR), and 38 patients (19.4%) as high risk (HR). Two-year overall survival (OS) was 47% (52% for LR/IR versus 29% for HR, P < .01) and 2-year disease-free survival was 39% (44% for LR/IR versus 21% for HR, P < .01). Relapse incidence was 30% (26% for LR/IR versus 44% for HR, P < .01). Treatment-related mortality was 29% at 2 years; this was similar for all DRI groups. In multiple regression analysis, HR DRI was associated with increased risk of relapse (hazard ratio, 2.07; 95% confidence interval [CI], 1.34 to 3.33; P = .02) and treatment failure (hazard ratio, 2.07; 95% CI, 1.35 to 3.18; P < .01) and decreased OS (hazard ratio, 2.11; 95% CI, 1.34 to 3.33; P < .01). In elderly patients, DRI is a significant prognostic factor for post-transplantation relapse, treatment failure, and mortality. Because of increased risk of relapse leading to poor survival in HR DRI, participation in clinical trials offering relapse prevention strategies after RIC alloHCT should be encouraged when available.

Reduced intensity conditioning allogeneic hematopoietic cell transplantation for adult acute myeloid leukemia in complete remission - a review from the Acute Leukemia Working Party of the EBMT

Acute myeloid leukemia is the most common indication for an allogeneic hematopoietic cell transplant. The introduction of reduced intensity conditioning has expanded the recipient pool for transplantation, which has importantly made transplant an option for the more commonly affected older age groups. Reduced intensity conditioning allogeneic transplantation is currently the standard of care for patients with intermediate or high-risk acute myeloid leukemia and is now most often employed in older patients and those with medical comorbidities. Despite being curative for a significant proportion of patients, post-transplant relapse remains a challenge in the reduced intensity conditioning setting. Herein we discuss the studies that demonstrate the feasibility of reduced intensity conditioning allogeneic transplants, compare the outcomes of reduced intensity conditioning versus chemotherapy and conventional myeloablative conditioning regimens, describe the optimal donor and stem cell source, and consider the impact of post-remission consolidation, comorbidities, center experience, and more intensive (reduced toxicity conditioning) regimens on outcomes. Additionally, we discuss the need for further prospective studies to optimize transplant outcomes.

Novel disease burden assessment predicts allogeneic transplantation outcomes in myelodysplastic syndrome

Among patients with myelodysplastic syndrome (MDS) undergoing hematopoietic cell transplantation (HCT), the impact of residual pretransplant cytogenetically abnormal cells on outcomes remains uncertain. We analyzed HCT outcomes by time of transplant disease variables, including (1) blast percentage, (2) percentage of cytogenetically abnormal cells and (3) Revised International Prognostic Scoring System (R-IPSS) cytogenetic classification. We included 82 MDS patients (median age 51 years (range 18-71)) transplanted between 1995 and 2013 with abnormal diagnostic cytogenetics. Patients with higher percentages of cytogenetically abnormal cells experienced inferior 5-year survival (37-76% abnormal cells: relative risk (RR) 2.9; 95% confidence interval (CI) 1.2-7.2; P=0.02; and 77-100% abnormal cells: RR 5.6; 95% CI 1.9-19.6; P<0.01). Patients with >10% blasts also had inferior 5-year survival (RR 2.9; 95% CI 1.1-7.2; P=0.02) versus patients with ⩽2% blasts. Even among patients with ⩽2% blasts, patients with 77-100% cytogenetically abnormal cells had poor survival (RR 4.4; 95% CI 1.1-18.3; P=0.04). Increased non-relapse mortality (NRM) was observed with both increasing blast percentages (P<0.01) and cytogenetically abnormal cells at transplant (P=0.01) in multivariate analysis. We observed no impact of disease burden characteristics on relapse outcomes due to high 1-year NRM. In conclusion, both blast percentage and percentage of cytogenetically abnormal cells reflect MDS disease burden and predict post-HCT outcomes.

Myeloablative, but not Reduced-Intensity, Conditioning Overcomes the Negative Effect of Flow-Cytometric Evidence of Leukemia in Acute Myeloid Leukemia

Stringent complete remission (CR) in acute myeloid leukemia (AML) requires the absence of both morphologic and flow cytometric evidence of disease. We have previously shown that persistent AML detected by flow cytometry (FC+) before reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (alloHCT) was associated with significantly increased relapse, shorter disease-free survival (DFS), and poorer overall survival (OS), independent of morphologic blast count. We evaluated the effect of FC status on outcomes of alloHCT for AML after either myeloablative conditioning (MAC) or RIC regimens in 203 patients (MAC, n = 80, and RIC, n = 123) with no morphologic evidence of persistent AML pretransplant on marrow biopsy. The allografts included 130 umbilical cord blood (UCB) and 73 sibling donors. We performed central review of pretransplant standard sensitivity FC to identify detectable FC+. Twenty-five patients were FC+, including 15 (18.7%) receiving MAC and 10 (8.1%) RIC alloHCT. Among RIC patients FC+ was associated with significantly inferior relapse, DFS, and OS (multiple regression HR, 3.8; 95% CI, 1.7 to 8.7; P < .01 for relapse; HR, 2.9; 95% CI, 1.4 to 5.9; P < .01 for DFS; and HR, 3.4; 95% CI, 1.7 to 7; P < .01 for OS). In contrast, FC+ status was not associated with relapse or decreased OS after MAC. These data suggest that MAC, but not RIC, overcomes the negative effect of pretransplant FC+ after sibling or UCB alloHCT. Therefore, a deeper pretransplant leukemia-free state is preferred for those treated with RIC.

Hemorrhagic cystitis after allogeneic hematopoietic cell transplantation: risk factors, graft source and survival

Although hemorrhagic cystitis (HC) is a common complication of allogeneic hematopoietic cell transplantation (alloHCT), its risk factors and effects on survival are not well known. We evaluated HC in a large cohort (n=1321, 2003-2012) receiving alloHCT from all graft sources, including umbilical cord blood (UCB). We compared HC patients with non-HC (control) patients and examined clinical variables at HC onset and resolution. Of these 1321 patients, 219 (16.6%) developed HC at a median of 22 days after alloHCT. BK viruria was detected in 90% of 109 tested HC patients. Median duration of HC was 27 days. At the time of HC diagnosis, acute GVHD, fever, severe thrombocytopenia and steroid use were more frequent than at the time of HC resolution. In univariate analysis, male sex, age <20 years, myeloablative conditioning with cyclophosphamide and acute GVHD were associated with HC. In multivariate analysis, HC was significantly more common in males and HLA-mismatched UCB graft recipients. Severe grade HC (grade III-IV) was associated with increased treatment-related mortality but not with overall survival at 1 year. HC remains hazardous and therefore better prophylaxis, and early interventions to limit its severity are still needed.

Allogeneic hematopoietic cell transplantation outcomes in acute myeloid leukemia: similar outcomes regardless of donor type

The use of alternative donor transplants is increasing as the transplantation-eligible population ages and sibling donors are less available. We evaluated the impact of donor source on transplantation outcomes for adults with acute myeloid leukemia undergoing myeloablative (MA) or reduced-intensity conditioning (RIC) transplantation. Between January 2000 and December 2010, 414 consecutive adult patients with acute myeloid leukemia in remission received MA or RIC allogeneic transplantation from either a matched related donor (n = 187), unrelated donor (n = 76), or umbilical cord blood donor (n = 151) at the University of Minnesota or Hôpital St. Louis in Paris. We noted similar 6-year overall survival across donor types: matched related donor, 47% (95% confidence interval [CI], 39% to 54%); umbilical cord blood, 36% (95% CI, 28% to 44%); matched unrelated donor, 54% (95% CI, 40% to 66%); and mismatched unrelated donor, 51% (95% CI, 28% to 70%) (P < .11). Survival differed based on conditioning intensity and age, with 6-year survival of 57% (95% CI, 47% to 65%), 39% (95% CI, 28% to 49%), 23% (95% CI, 6% to 47%), 47% (95% CI, 36% to 57%), and 28% (95% CI, 17% to 41%) for MA age 18 to 39, MA age 40+, or RIC ages 18 to 39, 40 to 56, and 57 to 74, respectively (P < .01). Relapse was increased with RIC and lowest in younger patients receiving MA conditioning (hazard ratio, 1.0 versus 2.5 or above for all RIC age cohorts), P < .01. Transplantation-related mortality was similar across donor types. In summary, our data support the use of alternative donors as a graft source with MA or RIC for patients with acute myeloid leukemia when a sibling donor is unavailable.

Monosomal karyotype at the time of diagnosis or transplantation predicts outcomes of allogeneic hematopoietic cell transplantation in myelodysplastic syndrome

Various cytogenetic risk scoring systems may determine prognosis for patients with myelodysplastic syndromes (MDS). We evaluated 4 different risk scoring systems in predicting outcome after allogeneic hematopoietic cell transplantation (alloHCT). We classified 124 patients with MDS using the International Prognostic Scoring System (IPSS), the revised International Prognostic Scoring System (R-IPSS), Armand's transplantation-specific cytogenetic grouping, and monosomal karyotype (MK) both at the time of diagnosis and at alloHCT. After adjusting for other important factors, MK at diagnosis (compared with no MK) was associated with poor 3-year disease-free survival (DFS) (27% [95% confidence interval, 12% to 42%] versus 39% [95% confidence interval, 28% to 50%], P = .02) and overall survival (OS) (29% [95% confidence interval, 14% to 44%] versus 47% [95% confidence interval, 36% to 59%], P = .02). OS but not DFS was affected by MK at alloHCT. MK frequency was uncommon in low-score R-IPPS and IPSS. Although IPSS and R-IPSS discriminated good/very good groups from poor/very poor groups, patients with intermediate-risk scores had the worst outcomes and, therefore, these scores did not show a progressive linear discriminating trend. Cytogenetic risk score change between diagnosis and alloHCT was uncommon and did not influence OS. MK cytogenetics in MDS are associated with poor survival, suggesting the need for alternative or intensified approaches to their treatment.

Hematopoietic stem-cell transplantation for advanced systemic mastocytosis

PURPOSE

Advanced systemic mastocytosis (SM), a fatal hematopoietic malignancy characterized by drug resistance, has no standard therapy. The effectiveness of allogeneic hematopoietic stem-cell transplantation (alloHCT) in SM remains unknown.

PATIENTS AND METHODS

In a global effort to define the value of HCT in SM, 57 patients with the following subtypes of SM were evaluated: SM associated with clonal hematologic non-mast cell disorders (SM-AHNMD; n = 38), mast cell leukemia (MCL; n = 12), and aggressive SM (ASM; n = 7). Median age of patients was 46 years (range, 11 to 67 years). Donors were HLA-identical (n = 34), unrelated (n = 17), umbilical cord blood (n = 2), HLA-haploidentical (n = 1), or unknown (n = 3). Thirty-six patients received myeloablative conditioning (MAC), and 21 patients received reduced-intensity conditioning (RIC).

RESULTS

Responses in SM were observed in 40 patients (70%), with complete remission in 16 patients (28%). Twelve patients (21%) had stable disease, and five patients (9%) had primary refractory disease. Overall survival (OS) at 3 years was 57% for all patients, 74% for patients with SM-AHNMD, 43% for those with ASM, and 17% for those with MCL. The strongest risk factor for poor OS was MCL. Survival was also lower in patients receiving RIC compared with MAC and in patients having progression compared with patients having stable disease or response.

CONCLUSION

AlloHCT was associated with long-term survival in patients with advanced SM. Although alloHCT may be considered as a viable and potentially curative therapeutic option for advanced SM in the meantime, given that this is a retrospective analysis with no control group, the definitive role of alloHCT will need to be determined by a prospective trial.

Comparison of minimal residual disease as outcome predictor for AML patients in first complete remission undergoing myeloablative or nonmyeloablative allogeneic hematopoietic cell transplantation

Minimal residual disease (MRD) is associated with adverse outcome in AML after myeloablative (MA) hematopoietic cell transplantation (HCT). We compared this association with that seen after nonmyeloablative (NMA) conditioning in 241 adults receiving NMA (n=86) or MA (n=155) HCT for AML in first remission with pre-HCT bone marrow aspirates assessed by flow cytometry. NMA patients were older and had more comorbidities and secondary leukemias. Three-year relapse estimates were 28% and 57% for MRD^neg and MRD^pos NMA patients, and 22% and 63% for MA patients. Three-year overall survival (OS) estimates were 48% and 41% for MRD^neg and MRD^pos NMA patients and 76% and 25% for MA patients. This similar OS after NMA conditioning was largely accounted for by higher non-relapse mortality (NRM) in MRD^neg (30%) compared to MRD^pos (10%) patients, whereas the reverse was found for MRD^neg (7%) and MRD^pos (23%) MA patients. A statistically significant difference between MA and NMA patients in the association of MRD with OS (P<0.001) and NRM (P=0.002) but not relapse (P=0.17) was confirmed. After adjustment, the risk of relapse was 4.51-times (P<0.001) higher for MRD^pos patients. These data indicate that the negative impact of MRD on relapse risk is similar after NMA and MA conditioning.