Erica D. Warlick

Allogeneic Stem Cell Transplantation for Adults with Myelodysplastic Syndromes: Importance of Pretransplant Disease Burden

Allogeneic stem cell transplantation is the only known curative therapy for myelodysplastic syndromes (MDS). We present the transplant outcomes for 84 adult MDS patients, median age 50 (18-69 years), undergoing allogeneic hematopoietic stem cell transplantation (HSCT) at the University of Minnesota between 1995 and 2007. By WHO criteria 35 (42%) had refractory anemia with excess blasts (RAEB-1 or 2), 23 (27%) had refractory cytopenia with multilineage dysplasia (RCMD) or RCMD and ringed sideroblasts (RCMD-RS), and the remaining 26 (31%) had refractory anemia (RA), myelodysplastic syndrome-unclassifiable (MDS-U), chronic myelomonocytic leukemia (CMML), myelodysplastic/myeloproliferative disease (MDS/MPD), or myelodysplastic syndrome-not otherwise specified (MDS-NOS). Graft source was related in 47 (56%), unrelated donor (URD) marrow in 11 (13%), and unrelated cord blood (UCB) in 26 (31%). The conditioning regimen included total body irradiation (TBI) in 94% of transplantations; 52 (62%) myeloablative (MA) and 32 (38%) nonmyeloablative (NMA) regimens. Cumulative incidence of neutrophil engraftment by day +42, acute graft-versus-host disease (aGVHD) by day +100, and chronic GVHD (cGVHD) by 1 year were 88% (80%-96%, 95% confidence interval [CI]), 43% (36%-50%, 95% CI), and 15% (10%-20%, 95% CI), respectively. One-year treatment-related mortality (TRM), relapse, disease-free survival (DFS), and overall survival (OS) were 39% (28%-50%, 95% CI), 23% (12%-32%, 95% CI), 38% (28%-48%, 95% CI), and 48% (38%-58%, 95% CI) respectively. Cumulative incidence of relapse at 1 year in patients with pre-HCT complete remission (CR) or <5% blasts was improved at 18% (8%-28%, 95% CI) compared to 35% (16%-54%, 95% CI) in patients with 5%-20% blasts (P = .07). Additionally, with MA conditioning, the incidence of relapse at 1 year trended lower at 16% (6%-26%, 95% CI) versus 35% (18%-52%, 95% CI) in NMA (P = .06), and a statistically significant decrease in relapse was noted in patients entering HCT with CR or <5% blasts with an incidence of 9% (0%-18%, 95% CI) (MA) versus 31% (11%-51%, 95% CI) (NMA) (P = 0.04). For those patients with > or =5% blasts, MA conditioning did not significantly decrease relapse rates. One-year TRM was similar between MA and NMA conditioning. For patients entering transplant in CR or with <5% blasts, prior treatment to reach this level did not impact rates of relapse or transplant-related mortality when all patients were analyzed; however, when broken down by conditioning intensity, there was a trend toward improved DFS in those NMA patients who were pretreated. Finally, 1-year DFS was similar using related donor peripheral blood stem cell (PBSC)/marrow, URD marrow, or UCB grafts. These data suggest that (1) blast percentage <5% at HSCT is the major predictor of improved DFS and relapse and prior treatment to reach this disease status may have value in leading to improved DFS; (2) MA conditioning is associated with lower relapse risk, particularly in patients with CR or <5% blasts, but is not able to overcome increased disease burden; (3) NMA conditioning yields equivalent TRM, DFS, and OS, and is reasonable in patients unsuited for MA conditioning; (4) the donor sources tested (PBSC, bone marrow [BM], or UCB) yielded similar outcomes.

Targeting natural killer cells to acute myeloid leukemia in vitro with a CD16 x 33 bispecific killer cell engager and ADAM17 inhibition.

Purpose: The graft versus leukemia effect by natural killer (NK) cells prevents relapse following hematopoietic stem cell transplantation. We determined whether a novel bispecific killer cell engager (BiKE) signaling through CD16 and targeting CD33 could activate NK cells at high potency against acute myelogenous leukemia (AML) targets. Experimental Design: We investigated the ability of our fully humanized CD16 × CD33 (CD16 × 33) BiKE to trigger in vitro NK cell activation against HL60 (CD33+), RAJI (CD33−), and primary AML targets (de novo and refractory) to determine whether treatment with CD16 × 33 BiKE in combination with an ADAM17 inhibitor could prevent CD16 shedding (a novel inhibitory mechanism induced by NK cell activation) and overcome inhibition of class I MHC recognizing inhibitory receptors. Results: NK cell cytotoxicity and cytokine release were specifically triggered by the CD16 × 33 BiKE when cells were cultured with HL60 targets, CD33+ de novo and refractory AML targets. Combination treatment with CD16 × 33 BiKE and ADAM17 inhibitor resulted in inhibition of CD16 shedding in NK cells, and enhanced NK cell activation. Treatment of NK cells from double umbilical cord blood transplant (UCBT) recipients with the CD16 × 33 BiKE resulted in activation, especially in those recipients with cytomegalovirus reactivation. Conclusion: CD16 × 33 BiKE can overcome self-inhibitory signals and effectively elicit NK cell effector activity against AML. These in vitro studies highlight the potential of CD16 × 33 BiKE ± ADAM17 inhibition to enhance NK cell activation and specificity against CD33+ AML, which optimally could be applied in patients with relapsed AML or for adjuvant antileukemic therapy posttransplantation. Clin Cancer Res; 19(14); 3844–55. ©2013 AACR.

CD16xCD33 bispecific killer cell engager (BiKE) activates NK cells against primary MDS and MDSC CD33+ targets

Myelodysplastic syndromes (MDS) are stem cell disorders that can progress to acute myeloid leukemia. Although hematopoietic cell transplantation can be curative, additional therapies are needed for a disease that disproportionally afflicts the elderly. We tested the ability of a CD16xCD33 BiKE to induce natural killer (NK) cell function in 67 MDS patients. Compared with age-matched normal controls, CD7(+) lymphocytes, NK cells, and CD16 expression were markedly decreased in MDS patients. Despite this, reverse antibody-dependent cell-mediated cytotoxicity assays showed potent degranulation and cytokine production when resting MDS-NK cells were triggered with an agonistic CD16 monoclonal antibody. Blood and marrow MDS-NK cells treated with bispecific killer cell engager (BiKE) significantly enhanced degranulation and tumor necrosis factor-α and interferon-γ production against HL-60 and endogenous CD33(+) MDS targets. MDS patients had a significantly increased proportion of immunosuppressive CD33(+) myeloid-derived suppressor cells (MDSCs) that negatively correlated with MDS lymphocyte populations and CD16 loss on NK cells. Treatment with the CD16xCD33 BiKE successfully reversed MDSC immunosuppression of NK cells and induced MDSC target cell lysis. Lastly, the BiKE induced optimal MDS-NK cell function irrespective of disease stage. Our data suggest that the CD16xCD33 BiKE functions against both CD33(+) MDS and MDSC targets and may be therapeutically beneficial for MDS patients.

Myeloablative versus reduced-intensity hematopoietic cell transplantation for acute myeloid leukemia and myelodysplastic syndromes

Purpose The optimal regimen intensity before allogeneic hematopoietic cell transplantation (HCT) is unknown. We hypothesized that lower treatment-related mortality (TRM) with reduced-intensity conditioning (RIC) would result in improved overall survival (OS) compared with myeloablative conditioning (MAC). To test this hypothesis, we performed a phase III randomized trial comparing MAC with RIC in patients with acute myeloid leukemia or myelodysplastic syndromes. Patients and Methods Patients age 18 to 65 years with HCT comorbidity index ≤ 4 and < 5% marrow myeloblasts pre-HCT were randomly assigned to receive MAC (n = 135) or RIC (n = 137) followed by HCT from HLA-matched related or unrelated donors. The primary end point was OS 18 months post-random assignment based on an intent-to-treat analysis. Secondary end points included relapse-free survival (RFS) and TRM. Results Planned enrollment was 356 patients; accrual ceased at 272 because of high relapse incidence with RIC versus MAC (48.3%; 95% CI, 39.6% to 56.4% and 13.5%; 95% CI, 8.3% to 19.8%, respectively; P < .001). At 18 months, OS for patients in the RIC arm was 67.7% (95% CI, 59.1% to 74.9%) versus 77.5% (95% CI, 69.4% to 83.7%) for those in the MAC arm (difference, 9.8%; 95% CI, -0.8% to 20.3%; P = .07). TRM with RIC was 4.4% (95% CI, 1.8% to 8.9%) versus 15.8% (95% CI, 10.2% to 22.5%) with MAC ( P = .002). RFS with RIC was 47.3% (95% CI, 38.7% to 55.4%) versus 67.8% (95% CI, 59.1% to 75%) with MAC ( P < .01). Conclusion OS was higher with MAC, but this was not statistically significant. RIC resulted in lower TRM but higher relapse rates compared with MAC, with a statistically significant advantage in RFS with MAC. These data support the use of MAC as the standard of care for fit patients with acute myeloid leukemia or myelodysplastic syndromes.

Similar Overall Survival Using Sibling, Unrelated Donor, and Cord Blood Grafts after Reduced-Intensity Conditioning for Older Patients with Acute Myelogenous Leukemia

For older patients with acute myeloid leukemia (AML), allogeneic hematopoietic cell transplantation (HCT) provides the best chance of long-term survival. A formal comparison between matched sibling (SIB), unrelated donor (URD), or umbilical cord blood (UCB) transplantation has not yet been reported in this setting. We compared reduced-intensity conditioning HCT in 197 consecutive patients 50 years and older with AML in complete remission from SIB (n = 82), URD (n = 35), or UCB (n = 80) transplantation. The 3-year cumulative incidences of transplantation-related mortality were 18%, 14%, and 24% with SIB, URD, and UCB transplantation, respectively (P = .22). The 3-year leukemia-free survival rates were 48%, 57%, and 33% with SIB, URD, and UCB transplantation, respectively (P = .009). In multivariate analysis, poor-risk cytogenetics was associated with relapse (hazard ratio, 1.7 [95% confidence interval, 1.0 to 3.0]; P = .04) and worse leukemia-free survival (hazard ratio, 1.6 [95% confidence interval, 1.0 to 2.5]; P = .03), whereas donor choice had no significant impact on overall survival (P = .73). Adjusted 3-year overall survival rates were 55% with SIB, 45% with URD, and 43% with UCB transplantation (P = .26). Until prospective studies are completed, this study supports the recommendation to consider SIB donor, URD, or UCB for HCT for older patients with AML in complete remission.

Reduced-intensity hematopoietic cell transplantation in older patients with AML/MDS: umbilical cord blood is a feasible option for patients without HLA-matched sibling donors.

Umbilical cord blood (UCB) has increased access to hematopoietic cell transplantation (HCT) for patients without HLA-matched sibling donors (MSD). We compared outcomes of HCT using MSD (N=38) or UCB (N=60) among older patients (age ⩾55 years) with AML or myelodysplastic syndromes (MDS). All patients received a reduced intensity regimen consisting of CY, fludarabine and 200 cGy TBI. Median age at HCT was 63 years for MSD and 61 years for UCB recipients. Among UCB recipients, 95% received two UCB units and 88% received 1–2 locus HLA-mismatched units to optimize cell dose. OS at 3-years was 37% for MSD and 31% for UCB recipients (P=0.21). On multivariate analysis, donor source (MSD vs UCB) did not impact risks of OS, leukemia-free survival and relapse or treatment-related mortality. UCB is feasible as an alternative donor source for reduced-intensity conditioning HCT among older patients with AML and MDS who do not have a suitable MSD.

Reduced intensity conditioning is superior to nonmyeloablative conditioning for older chronic myelogenous leukemia patients undergoing hematopoietic cell transplant during the tyrosine kinase inhibitor era

Tyrosine kinase inhibitors (TKIs) and reduced intensity conditioning (RIC)/nonmyeloablative (NMA) conditioning hematopoietic cell transplants (HCTs) have changed the therapeutic strategy for chronic myelogenous leukemia (CML) patients. We analyzed post-HCT outcomes of 306 CML patients reported to the Center for International Blood and Marrow Transplant Research aged 40 years and older undergoing RIC/NMA HCT from 2001 to 2007: 117 (38%) aged 40 to 49 years, 119 (39%) 50 to 59 years, and 70 (23%) 60 years or older. The majority (74%) had treatment with imatinib before HCT. At HCT, most patients aged 40 to 49 years were in chronic phase (CP) 1 (74%), compared with 31% aged 60 years or older. Siblings were donors for 56% aged 40 to 49 years; older cohorts had more unrelated donors. The majority received peripheral blood grafts and RIC across all age groups. 3 year overall survival (54%, 52%, and 41%), day + 100 grade II-IV acute GVHD (26%, 32%, and 32%), chronic GVHD (58%, 51%, and 43%), and 1-year treatment-related mortality (18%, 20%, and 13%) were similar across ages. The 3-year relapse incidence (36%, 43%, and 66%) and disease-free survival (35%, 32%, and 16%) were inferior in the oldest cohort. Importantly, for CP1 patients, relapse and disease-free survival were similar across age cohorts. Allogeneic RIC HCT for older patients with CML can control relapse with acceptable toxicity and survival in TKI-exposed CML, especially if still in CP1.

Reduced-intensity conditioning followed by related allografts in hematologic malignancies: long-term outcomes most successful in indolent and aggressive Non-Hodgkin lymphomas

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 123 patients (median age, 57 years; range, 23-70 years) with hematologic malignancies treated with a uniform RIC regimen of cyclophosphamide, fludarabine, and total-body irradiation (200 cGy) with or without antithymocyte globulin followed by related donor allogeneic HCT at the University of Minnesota between 2002 and 2008. The cohort included 45 patients with acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS), 27 with aggressive non-Hodgkin lymphoma (NHL), 8 with indolent NHL, 10 with Hodgkin lymphoma (HL), 10 with myeloma, and 23 with acute lymphocytic leukemia, chronic myelogenous leukemia, other leukemias, or myeloproliferative disorders. The probability of 4-year overall survival was 73% for patients with indolent NHL, 58% for those with aggressive NHL, 67% for those with HL, 30% for those with AML/MDS, and only 10% for those with myeloma. Corresponding outcomes for relapse in these patients were 0%, 32%, 50%, 33%, and 38%, and those for progression-free survival were 73%, 45%, 27%, 27%, and 10%. The incidence of treatment-related mortality was 14% at day +100 and 22% at 1 year. The incidence of grade II-IV acute graft-versus-host disease was 38% at day +100, and that of chronic graft-versus-host disease was 50% at 2 years. Multivariate analysis revealed superior overall survival and progression-free survival in patients with both indolent and aggressive NHL compared with those with AML/MDS, HL, or myeloma. Worse 1-year treatment-related mortality was observed in patients with a Hematopoietic Cell Transplantation Comorbidity Index score ≥ 3 and in cytomegalovirus-seropositive recipients. These results suggest that (1) RIC conditioning was well tolerated by an older, heavily pretreated population; (2) patients with indolent and aggressive NHL respond well to RIC conditioning, highlighting the importance of the graft-versus-lymphoma effect; and (3) additional peri-transplantation manipulations are needed to improve outcomes for patients with AML/MDS or myeloma receiving RIC conditioning before HCT.

Scoring System Prognostic of Outcome in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation for Myelodysplastic Syndrome

PURPOSE To develop a system prognostic of outcome in those undergoing allogeneic hematopoietic cell transplantation (allo HCT) for myelodysplastic syndrome (MDS). PATIENTS AND METHODS We examined 2,133 patients with MDS undergoing HLA-matched (n = 1,728) or -mismatched (n = 405) allo HCT from 2000 to 2012. We used a Cox multivariable model to identify factors prognostic of mortality in a training subset (n = 1,151) of the HLA-matched cohort. A weighted score using these factors was assigned to the remaining patients undergoing HLA-matched allo HCT (validation cohort; n = 577) as well as to patients undergoing HLA-mismatched allo HCT. RESULTS Blood blasts greater than 3% (hazard ratio [HR], 1.41; 95% CI, 1.08 to 1.85), platelets 50 × 10(9)/L or less at transplantation (HR, 1.37; 95% CI, 1.18 to 1.61), Karnofsky performance status less than 90% (HR, 1.25; 95% CI, 1.06 to 1.28), comprehensive cytogenetic risk score of poor or very poor (HR, 1.43; 95% CI, 1.14 to 1.80), and age 30 to 49 years (HR, 1.60; 95% CI, 1.09 to 2.35) were associated with increased hazard of death and assigned 1 point in the scoring system. Monosomal karyotype (HR, 2.01; 95% CI, 1.65 to 2.45) and age 50 years or older (HR, 1.93; 95% CI, 1.36 to 2.83) were assigned 2 points. The 3-year overall survival after transplantation in patients with low (0 to 1 points), intermediate (2 to 3), high (4 to 5) and very high (≥ 6) scores was 71% (95% CI, 58% to 85%), 49% (95% CI, 42% to 56%), 41% (95% CI, 31% to 51%), and 25% (95% CI, 4% to 46%), respectively (P < .001). Increasing score was predictive of increased relapse (P < .001) and treatment-related mortality (P < .001) in the HLA-matched set and relapse (P < .001) in the HLA-mismatched cohort. CONCLUSION The proposed system is prognostic of outcome in patients undergoing HLA-matched and -mismatched allo HCT for MDS.

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

Reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (allo-HCT) can cure patients with AML in CR. However, relapse after RIC allo-HCT may indicate heterogeneity in the stringency of CR. Strict definition of CR requires no evidence of leukemia by both morphologic and flow cytometric criteria. We re-evaluated 85 AML patients receiving RIC allo-HCT in CR to test if a strict definition of CR had direct implications for the outcome. These patients had leukemia immunophenotype documented at diagnosis and analyzed at allo-HCT. Eight (9.4%) had persistent leukemia by flow cytometric criteria at allo-HCT. The patients with immunophenotypic persistent leukemia had a significantly increased relapse (hazard ratio (HR): 3.7; 95% confidence interval (CI): 1.3–10.3, P=0.01) and decreased survival (HR: 2.9; 95% CI: 1.3–6.4, P<0.01) versus 77 patients in CR by both morphology and flow cytometry. However, the pre-allo-HCT bone marrow (BM) blast count (that is, 0–4%) was not significantly associated with risks of relapse or survival. These data indicate the presence of leukemic cells, but not the BM blast count affects survival. A strict morphologic and clinical lab flow cytometric definition of CR predicts outcomes after RIC allo-HCT, and therefore is critical to achieve at transplantation.