Nonmyeloablative Preparative Regimens Research Articles

Factors Predicting Efficacy and Toxicity of Post Transplantation Cyclophosphamide for Graft Versus Host Disease Prevention in Hematopoietic Cell Transplantation Recipients: Interim Data of an Ongoing Study

Introduction: Post-transplant cyclophosphamide (PTCy) following allogeneic stem cell transplantation (allo HCT) to decrease the risk of graft vs host disease (GVHD) has transformed the field. Since initially demonstrating safety and efficacy following non-myeloablative (NMA) conditioning in patients (pts) receiving haplo-identical donor (haplo) transplants, PTCy has been implemented in matched related donor (MRD), matched unrelated donor (MUD), and mismatched unrelated donor (mMUD) transplantation. However, PTCy can contribute to toxicity, and some pts still develop GVHD. A personalized approach to PTCy dosing could provide more effective prevention of GVHD and less toxicity without compromising graft versus tumor activity. We present interim results of our study investigating the genetic and metabolic factors that modulate Cy metabolism and the extent to which these drive its immunomodulatory effects. Methods: All adult pts receiving allo HCT with MRD, MUD or haplo donor were eligible. All recipients received NMA preparative regimen which included Cy 14.5 mg/kg on days -6 / -5 and PTCy (50 mg/kg) on days +3 / +4. Pts underwent standard clinical evaluations post-transplant for up to 2 yrs. This study was IRB approved and registered under NCI clinical trial (NCT03555851). Pharmacogenomics (PG): Recipient's germline DNA was extracted from buccal swabs obtained prior to transplant. Candidate genes genotyped using next-generation sequencing included CYP2B6, CYP3A4/5, CYP2C8/9, CYP2C19, ALDH1A1/3A1, GSTP1, GSTM1, and GSTA1. Pharmacokinetics (PK): Blood samples were obtained on day -6 and day +3 within 15 minutes after the end of Cy infusion, and 2, 4, 8, 16, 20, and 24 hours (hrs) after infusion start. Concentrations of Cy and its metabolites hydroxycyclophosphamide (HCY) carboxyethylphosphoramide mustard (CEPM) and phosphoramide mustard (PM) were analyzed using a Waters Quattro Premier triple quadrupole mass spectrometer coupled to an Acquity UPLC system. Immune Profiling (IP): Mononuclear cells were isolated and cryopreserved from haplo donor apheresis products as well as from pts prior to transplant on day -6, day 0, and post-transplant days +3, +5, +14, +30, and 3, 6 and 12 months (mos) post-transplant. Immune effector and memory subsets surveyed by flow cytometry included: CD4, CD8 T cells and regulatory T cells (Treg). Descriptive analysis of recipient PG, cyclophosphamide (and related metabolites) PK, and T cell profiling was performed. Results: Ten pts who underwent allo HCT were evaluated. This included 6 haplo, 2 MRD, and 2 MUD recipients. All pts received NMA conditioning with fludarabine, cyclophosphamide and irradiation. Four pts developed aGVHD, 1 pt grade I (MUD), 2 pts grade II (haplo), and 1 pt grade III (haplo). Two pts died on study from relapsed disease, 1 pt was taken off study after 6 mos with relapsed disease, 7 pts are alive, 5 of whom completed 2 years of follow up. Successful PG analysis was completed in 9 pts. PK assessments were completed in 10 pts with wide interpatient variability, Table 1 summarizes the median and Cmax range for each measured Cy metabolite. Pts with aGVHD had similar mean Cy metabolite Cmax compared to pts who did not develop aGVHD (Table 1). IP profiling in 10 pts showed relative T cell subset distribution (% PBMC) first peaked at day +5 (34.4±9.9%), with mainly T effector subsets and Treg detected, and nadired at 1 mo (10.8±7.5%) with an overrepresentation of central T memory cells followed by a rebound at 2 mo (34.6±16.7%) driven by CD8 effector & effector memory cells. The 4 pts with aGVHD trended towards higher TEff:Treg ratio at day +5 (2±0.6 vs 3.9±1.5); a trend also observed in the transplanted product (20.6±2.4vs 12±1.8). Conclusion: Our results show the feasibility of assessing PK, PG, and IP in pts receiving PTCy. Early IP of both pts and transplanted product may pinpoint immune imbalance associated with aGHVD later masked during immune reconstitution. Study of a large number of additional pts may clarify the association between early IP and Cy metabolites concentrations with immune profile and with risk of aGVHD. Candidate single nucleotide polymorphisms will be used to evaluate the association of pharmacogenetics with Cy PK, IP, and clinical outcomes. We hope these data will help guide individualized dosing of PTCy to improve effectiveness and minimize toxicity. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Significance of Degree of HLA Disparity When Using Haploidentical Donors with T-Replete PBSC and Post-Transplantation Cyclophosphamide (PTCy) in Acute Myeloid Leukemia (AML) in First Complete Hematologic Remission (CR1)

Background: Haploidentical allogeneic hematopoietic cell transplantation (haplo) has expanded applicability of the procedure to patients for whom a suitable HLA compatible donor was not available in the past. A small multicenter retrospective study of 185 patients with hematologic malignancies who received a nonmyeloablative preparative regimen followed by infusion of bone marrow (BM) hematopoietic cells from haploidentical donors showed no significant association between the number of HLA mismatches (HLA-A, -B, -C, and -DRB1 combined) and risk of acute grade 2-4 graft-versus-host disease (GVHD) (hazard ratio [HR]=0.89; P=0.68 for 3-4 mismatches vs fewer antigen mismatches). This haploidentical transplant platform has certainly evolved. Nowadays, G-CSF mobilized peripheral blood stem cells (PBSC) are commonly used owing to its increased convenience vis-à-vis performing a BM harvest.Study population: Here, we evaluate post transplant outcomes when using haploidentical donors with T-replete PBSC and PTCy in AML in CR1. A total of 494 patients (4/8 HLA mismatch (group 1)=360, 2-3/8 HLA mismatch (group 2)=134) underwent the procedure at an EBMT participating center. The primary endpoints were cumulative incidences of grade 2-4 acute GVHD and chronic (all grades) GVHD. Secondary endpoints included cumulative incidence of relapse (RI), non-relapse mortality (NRM), leukemia-free (LFS) and overall survival (OS) and GVHD-free relapse-free survival (GRFS).Results: Group 1 and group 2 were not statistically different in regards to median age at allografting (54.1 vs. 56.1 years, p=0.51), median year of haplo transplantation (2018 vs. 2018, p=0.36), incidence of de novo AML (86.4% vs. 88.1%, p=0.63), Karnofsky equal or more than 90 (77.5% vs. 79.1%, p=0.70), and use of myeloablative conditioning (MAC) (44.7% vs. 48.5%, p=0.45). Patients in group 1 had a longer time from diagnosis to haplo-transplantation (5.3 vs. 4.9 months, p=0.03). In multivariate analysis, group 1 and group 2 did not differ in cumulative incidence of grade 2-4 acute GVHD (Hazard ratio (HR)=0.89 (95%CI=0.62-1.26), p=0.51) but group 1 had a significantly higher incidence of chronic (all grades) GVHD (HR=1.49 (95%CI=1.02-2.16), p=0.04). There was no difference in RI (HR=0.73 (95%CI=0.47-1.14), p=0.17), NRM (HR=1.25 (95%CI=0.78-2.02), p=0.36), LFS (HR=0.95 (95%CI=0.69-1.31), p=0.76), OS (HR=1.09 (95%CI=0.76-1.55), p=0.64) and GRFS (HR=1.07 (95%CI=0.81-1.42), p=0.64) between the groups. Presence of adverse cytogenetics was independently associated with higher RI (HR=1.90 (95%CI=1.20-2.99), p=0.006), inferior LFS (HR=1.59 (95%CI=1.15-2.19), p=0.005), inferior OS (HR=1.48 (95%CI=1.05-2.08), p=0.03), and worse GRFS (HR=1.54 (95%CI=1.17-2.04), p=0.002).Conclusion: Results show that patients undergoing haplo-transplantation with 4/8 (vs. 2-3/8) HLA mismatches have a higher incidence of chronic GVHD (all grades) without adversely affecting acute grade 2-4 GVHD, RI, LFS, OS and GRFS. DisclosuresLabopin: Jazz Pharmaceuticals: Honoraria. Bazarbachi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hikma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Blaise: Jazz Pharmaceuticals: Honoraria. McDonald: BioCryst Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Forcade: Novartis: Other: travel grant. Ciceri: IRCCS Ospedale San Raffaele: Current Employment. Mohty: Takeda: Honoraria; Astellas: Honoraria; Adaptive Biotechnologies: Honoraria; Novartis: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Sanofi: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Jazz: Honoraria, Research Funding; Pfizer: Honoraria; Amgen: Honoraria.

Results Of a Phase I Study Of Clofarabine and 2 Gy Total Body Irradiation (TBI) As a Non-Myeloablative Preparative Regimen For Hematopoietic Stem Cell Transplantation (HSCT) In High Risk Children With Hematologic Malignancies: A Multi-Center TACL Study

BackgroundReduced intensity conditioning (RIC) regimens for HSCT in hematologic malignancies are successful in reducing transplant related mortality (TRM) and making HSCT available for a select group of high risk patients. Despite HSCT and its associated graft-versus-leukemia (GVL) effect, the risk of relapse remains high with RIC regimens. Clofarabine is a second generation purine analogue with significant anti-leukemic activity in pediatric patients. We postulated that a non-myeloablative (NMA) preparative regimen with clofarabine and 2 Gy TBI may lead to sustained engraftment with low TRM in high-risk children with hematologic malignancies undergoing related and unrelated HSCT. Patient and MethodsThe primary aim of the Phase I study was to establish the maximum feasible dose (MFD) of clofarabine in conjunction with 2 Gy TBI that leads to durable engraftment with acceptable toxicity in a high-risk pediatric population. Patients between 1-21 years of age with leukemia and undergoing HSCT with significant co-morbidities or any condition that will make them at high risk of TRM with a myeloablative regimen were eligible. Patients had to be in CR or CRp (no morphologic disease, ANC >0.75 x 109/L but without platelet recovery) status prior to HSCT with a PS score of >50 with no active infection, a creatinine clearance of >70 ml/min/1.73m2 and liver enzymes <5X ULN. Patients were stratified according to donor source- related donor (RD) or unrelated donor (UD; 10/10 or 9/10 HLA match) arms. Peripheral blood stem cells (PBSC) were the preferred graft source (BM was allowed for RD only). Cyclosporine and mycophenolate mofetil were used as GVHD prophylaxis. A phase I modified 3+3 design was used with engraftment, severe toxicity and TRM as study end-points. Starting dose of clofarabine was 40 mg/m2 x 5 days with escalation to 52 mg/m2 in case of non-engraftment and acceptable toxicity in the first cohort or de-escalation to 30 mg/m2for dose limiting toxicity (DLT) or TRM. Patients completed the dose evaluation at 100 days post-HSCT, but were followed for 1 year post- transplant and were censored at relapse or death. ResultsSeventeen pediatric patients with a median age of 9 years (range 1-18) enrolled on the study between 7/2010 and 5/2013 and 16 have completed 100-day post-HSCT evaluations. Ten patients had ALL (CR2 =5; CR3 =4 and CR4=1) while 7 had AML (PIF=1; CR1= 1; CR2=3 and secondary AML=3); 9 received UD and 8 received RD grafts. All patients were heavily pre-treated and the indication for the NMA approach was: prior HSCT (n=6), prior liver transplant (n=2), trisomy 21 (n=2) or significant comorbidities (n=7).There was no observed TRM or DLT in the first cohort (clofarabine 40 mg/m2/dose x 5 days) in both the UD and RD strata. The dose was escalated to 52 mg/m2/dose in the next cohorts. All patients tolerated the maximum dose well and no DLT was reported. Significant non-hematologic toxicities (CTC ≥ grade 3) observed were- transient transaminitis (ALT increase in 30% and AST increase in 17%); anorexia (35%) and skin reactions in 16%.PBSC was the stem cell source for all patients, except 3 who had received BM from a RD. Median cell dose was 6.8 x 106 CD34+/kg (range: 2.2-11.5 x 106/kg). All patients achieved neutrophil and platelet engraftment at a median of 19 days (range: 9-25) and 11 days (range: 3-29), respectively. CD3 chimerism analysis at day+30 post-transplant showed donor engraftment in all patients; 15 were full donor (>95%) and 2 showed mixed chimerism (53% and 81% donor).Ten (58%) patients developed acute GVHD, 8 (47%) had ≤ Grade II and 2 (11%) had Grade III acute GVHD. Seven (41%) patients relapsed (4/8 RD and 3/9 in UD arms) at a median time of +106 days (range: 88-190) post-HSCT and all of them died due to disease. Ten patients (58%) are alive and disease free; six have completed 1 year evaluations and 4 are still in follow-up. ConclusionThe MFD of clofarabine in combination with 2 Gy TBI was determined to be 52 mg/m2. This regimen is well tolerated and leads to brisk and sustained donor engraftment in a pediatric population that is at high risk of TRM. Disclosures:Thompson:Sanofi Aventis: Speakers Bureau.

Lentivirus-mediated gene therapy for Fabry disease

Enzyme and chaperone therapies are used to treat Fabry disease. Such treatments are expensive and require intrusive biweekly infusions; they are also not particularly efficacious. In this pilot, single-arm study (NCT02800070), five adult males with Type 1 (classical) phenotype Fabry disease were infused with autologous lentivirus-transduced, CD34+-selected, hematopoietic stem/progenitor cells engineered to express alpha-galactosidase A (α-gal A). Safety and toxicity are the primary endpoints. The non-myeloablative preparative regimen consisted of intravenous melphalan. No serious adverse events (AEs) are attributable to the investigational product. All patients produced α-gal A to near normal levels within one week. Vector is detected in peripheral blood and bone marrow cells, plasma and leukocytes demonstrate α-gal A activity within or above the reference range, and reductions in plasma and urine globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) are seen. While the study and evaluations are still ongoing, the first patient is nearly three years post-infusion. Three patients have elected to discontinue enzyme therapy.

Induction of Tolerance for Long-Term Liver Allograft Survival Without Immunosuppression in Cynomolgus Monkeys

Background Spontaneous liver tolerance occurs only in highly selected patients with stable liver function for several years. There is an unmet need for a safe and reliable regimen allowing rapid immunosuppression (IS) withdrawal. Herein, we investigated if tolerance to liver allografts can be achieved in cynomolgus macaques using four different non-myeloablative preparative regimens. Methods Nine combined liver and bone marrow cell transplants were performed in cynomolgus monkeys, using three various conditioning regimens (group A, B, C). All animals received total body irradiation (1.5 Gy), thymic irradiation (7 Gy), and ATGAM (50 mg/kg) prior to the transplant. Rituximab (20 mg/kg), anti-CD40 (50 mg/kg), and anti-CD2 (1-2 mg/kg) monoclonal antibodies were given according to Table 1. Four additional livers (group D) were transplanted with the same protocol as in group C, but BMT was omitted. All IS was completely discontinued by day 55. Results All recipients developed multilineage mixed chimerism. Group A showed severe rejection with CD8+ T effector memory (Tmem) cell expansion. Improved pretransplant host Tmem depletion using anti-CD2 in group B resulted in prolonged multlineage MC and graft acceptance. Animal B(2), however, developed grade 1 GVHD in skin and rectum. The addition of post-transplant anti-CD2 in group C depleted donor Tmem, prevented GVHD, while permitting prolonged MC and extended IS-free graft survival. With the exclusion of BMT (group D), passenger leukocytes in the liver promoted transient MC. Even when chimerism was lost and memory T cells recovered, group D maintained normal graft function without any inflammation seen in protocol biopsies beyond six months. The percentage of Tregs in total CD4 were elevated over baseline during the period of stable graft function in Groups C and D animals.Conclusions This is the first proof of concept study demonstrating long-term stable liver allograft function in nonhuman primates using a non-myeloablative treatment regimen to facilitate rapid IS withdrawal. The results demonstrate the ability of anti-CD2 to control Tmem responses, and that liver transplantation alone (without infusion of DBM cells) generates MC and is associated with long-term graft survival after complete IS withdrawal. NIAID R56AI122332-01A1. AASLD Career Development Award in the Memory of the University of Michigan Transplant Team. Columbia University Irving Institute for Clinical Research.

Phase I Study of Clofarabine and 2-Gy Total Body Irradiation as a Nonmyeloablative Preparative Regimen for Hematopoietic Stem Cell Transplantation in Pediatric Patients with Hematologic Malignancies: A Therapeutic Advances in Childhood Leukemia Consortium Study

Clofarabine is a purine nucleoside analog with immunosuppressive and antileukemic activity and its inclusion in reduced-intensity regimens could potentially improve outcomes. We performed a prospective phase I study of clofarabine combined with 2 Gy total body irradiation (TBI) as a nonmyeloablative preparative regimen for allogeneic stem cell transplantation in pediatric patients who were considered at high risk of mortality from standard myeloablative regimens. The main goal of the study was to delineate the maximum feasible dose (MFD) of clofarabine in combination with 2 Gy TBI. Eighteen patients, 1 to 21 years of age and in complete remission, were enrolled in 2 strata (matched related donor and unrelated donor) and evaluated for day100 dose-limiting events (DLE) (nonengraftment, nonrelapse mortality [NRM], and severe renal insufficiency) after receiving clofarabine at the starting dose level of 40 mg/m2. All 6 patients (3 in each stratum) engrafted with no day 100 DLE seen in the first cohort. The dose was increased to 52 mg/m2 in the next and an expanded cohort (total of 12 patients) and no DLE were observed at day 100 and at the 1-year study endpoint. The regimen was well tolerated with transient transaminitis and gastrointestinal and skin reactions as the common reversible toxicities observed with clofarabine. The dose of 52 mg/m2 of clofarabine was deemed the MFD. Disease relapse led to mortality in 6 (33%) patients during follow-up with 1-year event-free survival and overall survival of 60% (95% confidence interval [CI], 34 to 79) and 71% (95% CI, 44 to 87), respectively. This regimen leads to successful engraftment using both related and unrelated donors with exceptionally low rates of NRM.

P042 Impact of minor HLA allelic mismatches on outcomes of hematopoietic cell transplants

Aim The risk of graft failure or graft-versus-host disease (GvHD) after Hematopoietic cell transplantation (HCT) strictly depends the degree of matching of histocompatibility antigens between the donor and recipient. In some cases due to rare HLA alleles or clinical emergency, it is difficult or even impossible to find a perfectly matched donor. HLA minor (allelic) mismatched (MM) donors (for example, B∗35:02 vs B∗35:05) have been shown to be an option for such patients. The goal of this study was to retrospectively analyze how class I minor MM HLA affect HCT outcomes. Methods The study population included 18 adult patients with a variety of hematological diseases who underwent HCT from 2001 through 2011 using unrelated donors with MM at class I HLA region. The control group included 55 patients transplanted within the same period of time who received 10/10 (HLA-A, -B, -C, -DR, -DQB1) matched HCTs. The groups were matched according to sex, age, diagnosis and pre-transplant protocol. High resolution HLA typing was performed using sequence based typing. The variables tested included total number of amino acid substitutions (AAS), locations of the AAS ( α helix or β strand), affected pockets (A, B, C, D, E, F), TCR or peptide binding sites, and dissimilarity score (DSS). These parameters were estimated using the HISTOCHECK computer algorithm. Statistical analysis comparing HLA matching parameters with the incidence of acute (a) and chronic (c) GvHD was done by ANOVA. Results All donor-recipient combinations were allele matched for DRB1 and DQB1 loci. Allelic MM transplants with a non-myeloablative preparative regimen was associated with a higher incidence of cGvHD (p = 0.009) Allelic MM at any class I locus was associated with increased risk of grade III-IV aGvHD (p = 0.0425). Variables predictive of any grade aGvHD were AAS in any HLA pocket but C (p Conclusions AAS in peptide binding pockets in the setting of HLA class I MM donor-recipient combinations are at higher risk for GvHD and as such provide additional insight into donor search strategies.

Feasibility and Outcome of Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplant High-Dose Cyclophosphamide for Children and Adolescents with Hematologic Malignancies: An AIEOP-GITMO Retrospective Multicenter Study

Post-transplant high-dose cyclophosphamide (PTCy) is a novel approach to prevent graft-versus-host disease (GVHD) and rejection in patients given haploidentical hematopoietic stem cell transplantation (HSCT). Thirty-three patients with high-risk hematologic malignancies and lacking a match-related or -unrelated donor were treated with PTCy haploidentical HSCT in 5 Italian AIEOP centers. Nineteen patients had a nonmyeloablative preparative regimen (57%), and 14 patients received a full myeloablative conditioning regimen (43%). No patients received serotherapy; GVHD prophylaxis was based on PTCy (50 mg/kg on days +3 and +4) combined with mycophenolate plus tacrolimus or cyclosporine A. Neutrophil and platelet engraftment was achieved on days +17 (range, 14 to 37) and +27 (range, 16 to 71). One patient had autologous reconstitution for anti-HLA antibodies. Acute GVHD grades II to IV and III to IV and chronic GVHD developed in 22% (95% CI, 11 to 42), 3% (95% CI, 0 to 21), and 4% (95% CI, 0 to 27) of cases, respectively. The 1-year overall survival rate was 72% (95% CI, 56 to 88), progression-free survival rate was 61% (95% CI, 43 to 80), cumulative incidence of relapse was 24% (95% CI, 13 to 44), and transplant-related mortality was 9% (95% CI, 3 to 26). The univariate analysis for risk of relapse incidence showed how 3 significant variables, mother as donor (P = .02), donor gender as female (P = .04), and patient gender as female (P = .02), were significantly associated with a lower risk of relapse. Disease progression was the main cause of death. PTCy is a safe procedure also for children and adolescents who have already received several lines of chemotherapy. Among the different diseases, a trend for better 1-year rates of overall survival was obtained for nonacute leukemia patients.

Disease Risk Index Is the Major Predictor of Outcome Following Myeloablative Haploidentical Hematopoietic Stem Cell Transplantation (haplo-HSCT) and Post-Transplant Cyclophosphamide (PT/Cy)

Disease Risk Index is the Major Predictor of Outcome Following Myeloablative Haploidentical Hematopoietic Stem Cell Transplantation (haplo-HSCT) and Post-Transplant Cyclophosphamide (PT/Cy)Although non-myeloablative (NMA) haplo-HSCT utilizing PT/Cy results in low rates of GVHD, infection, and non-relapse mortality (NRM), relapse remains the predominant cause of treatment failure, occurring in up to 50% of patients. To reduce the risk of relapse often associated with the use of NMA preparative regimens, we have developed a myeloablative haplo-HSCT utilizing PT/Cy. Sixty-four patients have been transplanted following either Busulfan-based (n=20) or TBI-based (n=44) myeloablative conditioning, T-cell replete PBSC infusion, PT/Cy, and tacrolimus/mycophenolate mofetil. Median age was 43 (range 21-60). Patient characteristics included a high/very high disease risk by the Dana-Farber/CIBMTR disease risk index (DRI) in 32 patients (50%), KPS<90 in 69%, and comorbidity index (CMI) of ≥2 in 58% of patients. The most common indications for transplant were AML, ALL, and advanced-phase CML in 55%, 20% and 12% of patients respectively. Median follow-up for surviving patients was 24 months. All patients have engrafted with no late graft failure. Grade II-IV, III-IV acute GVHD and moderate-severe chronic GVHD occurred in 46%, 23%, and 30% respectively. One-year NRM was 10%. Predicted three-year overall survival (OS), disease-free survival (DFS), and relapse are 53%, 53%, and 26% respectively. In multivariate analysis, high/very high DRI was the most significant negative predictor of OS (HR 13.26, p<0.001), followed by CMI≥2 (HR 3.54, p=0.01) and age (HR 1.26, p=0.038, per each 5 year increase in age). DRI was also significantly associated with DFS (HR 10.84, p<0.001), NRM (HR 15.0, p=0.004), and relapse (HR 8.85, p=0.004). In the 32 patients with standard risk disease (low/intermediate DRI), outcomes were significantly improved with one-year NRM of 0% and predicted 3-year OS, DFS, and relapse of 79%, 74% and 9% respectively. Conditioning regimen (TBI vs. Busulfan) had no significant impact on outcome. This analysis confirms that DRI is a strong predictor of outcome following myeloablative haplo-HSCT and PT/Cy and adds to a growing body of literature suggesting that haplo-HSCT is a safe and effective transplant option for patients lacking a matched sibling donor. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Thymoglobulin Decreases the Need for Immunosuppression at 12 Months after Myeloablative and Nonmyeloablative Unrelated Donor Transplantation: CBMTG 0801, a Randomized, Controlled Trial

Background: Randomized trials (RCT) have shown that anti-thymocyte globulin (ATG) decreases the incidence and severity of chronic graft-versus-host disease (cGVHD) following unrelated donor transplants, but it is not used universally. We conducted a multicenter RCT to test whether the addition of Thymoglobulin® (TG) to both myeloablative (MA) and nonmyeloablative (NMA) preparative regimens results in a decrease in use of immunosuppression for cGVHD, leading to improvements in quality of life but without an increase in mortality, disease relapse or serious infections.Methods: Multicentric (Canada and Australia, 12 centres), open label RCT, in patients having transplantation from unrelated donors for a hematologic malignancy. Inclusion criteria: age 16-70, MA or NMA preparative regimen, bone marrow or peripheral blood graft, fully major histocompatibility complex (MHC) matched (HLA-A, B, C and DRB1) or 1-antigen/allele mismatched donor. Subjects were allocated by minimization procedure to TG or No Thymoglobulin® (NoTG). The TG arm received 0.5, 2.0, 2.0 mg/kg of TG on days -2, -1 and +1 respectively. Analyses were on a modified intention-to-treat basis for patients actually transplanted. The primary end-point was freedom from cGVHD at 12 months from transplantation defined as withdrawal of all systemic immunosuppressive agents (IST) without resumption up to 12 months after transplantation. Secondary end-points included relapse, serious infections, acute and chronic GVHD, overall survival (OS), and quality of life (QoL). QoL measures included Life Happiness Rating, Affect Balance Scale, FACT-BMT, EuroQol 5D, Center for Epidemiologic Studies-Depression Scale, Chronic GVHD Symptom Scale, and the Illness Intrusiveness Ratings Scale, collected prior to randomization and at 12 months. Treatment group comparisons, adjusted for baseline values, were made using logistic regression, analysis of covariance or the Cox proportional hazards model; in the presence of competing risks the method of Fine and Gray was implemented.Results: Data were locked on July 7, 2014. Two hundred and three (203) subjects consented and were randomized; seven were non-evaluable (6 withdrew before transplant, 3 having relapsed; 1 withdrew consent day 139), leaving 196 subjects for analysis. One subject was later found ineligible but was analyzed. Study populations were balanced for clinical risk factors. Sixty-seven percent (67%) received myeloablative conditioning, and 88% peripheral blood. Eighty-three percent (83%) were 8/8 HLA matched. Overall, freedom from IST at 12 months was twice as high in the TG group 37.4% vs. 16.5%, p=0.0001, even after adjusting for clinical factors: odds ratio 4.25 (95% CI, 1.87 – 9.67); p=0.006 or separately analyzing the MA and NMA groups. Acute GVHD (I-IV) and moderate/severe NIH grades of cGVHD were higher in the NoTG group, while relapse, non-relapse mortality, serious infections and OS were not significantly different. CGVHD (mild/mod/severe) was borderline significant using Fine and Gray (p=0.12; HR=0.65 95% CI (0.38 – 1.11) but the Cox result was significant p=0.01 (HR=0.48 95% CI (0.27 -0.85). Life Happiness was higher and Chronic GVHD Symptoms lower in the TG group as compared to the NoTG group (p=0.014 and 0.017 respectively); no other measure differed significantly.Conclusions: Addition of TG to the conditioning regimen for unrelated donor transplantation results in twice the likelihood of being alive and off immunosuppression at 12 months after transplantation, and is associated with modest improvements in some aspects of QoL. This benefit is seen without an increase in relapse, serious infections or non-relapse mortality. Our data support the use of TG in both MA and NMA preparative regimens before unrelated donor transplantation.TableTG N=97NoTG N=99p-valuePRIMARY ENDPOINTFreedom from IST at 12 mos37.4%16.5%0.001Myeloablative Subanalysis37.9%19.7%0.02Nonmyeloablative Subanalysis36.4%9.7%0.01SECONDARY ENDPOINTSAcute GVHD I-IV58.6%73.2%0.012cGVHD (NIH criteria)22.4%33.4%0.01 (Cox) 0.12 (Fine and Gray)cGVHD (NIH) Mod/Severe4.4%31%0.0001Serious infections38.4%37.1%0.85Relapse10.1%13.4%0.27Non-relapse mortality (12 mo)19.2%24.1%0.45Survival (12 mo)74.7%64.5%0.16Life Happiness Rating (QoL)*7.405.970.014GVHD Symptom Scale (QoL)*14.9520.930.017* Other QoL measures not significant DisclosuresWalker:Sanofi: Research Funding. Off Label Use: Thymoglobulin which is the intervention in this randomized trial. Kuruvilla:Sanofi Aventis: Honoraria. Popradi:Sanofi: Honoraria.

Non-Myeloablative Conditioning Targeting Host Immunosuppression Is Successful in Matched Sibling Donor Stem Cell Transplantation for Hemoglobinopathies in Children

▪Background: Myeloablative hematopoietic cell transplantation (HCT) provides a cure for children with hemoglobinopathies, but transplant related early and late morbidity remains a challenge. Toxicities associated with myeloablative chemotherapy include early complications such as mucositis, hemorrhagic cystitis, seizures, and hepatic injury. Late effects such as infertility and compromised linear growth impair long-term quality of life, often decreasing enthusiasm for the procedure. Reduced intensity preparative regimens are especially attractive in children with non-malignant disorders to mitigate these toxicities but have been associated with increased risk of graft rejection. The primary objective of this study was to determine the toxicity and efficacy of a non-myeloablative preparative regimen using alemtuzumab, fludarabine, and melphalan followed by HCT from HLA matched related donors (MRD) in children with hemoglobinopathies.Methods: Following institutional review board approval, and parent and/or patient consent, participants were enrolled at 18 centers. Children < 21 years of age with severe sickle cell disease (SCD) manifestations, or transfusion dependent (> 8 red blood cell transfusions per year) thalassemia with a MRD and a performance status > 40 were eligible for inclusion. The preparative regimen included alemtuzumab (total dose 48 mg) IV (between days –22 and –19), fludarabine (30 mg/m2/day) (days –8 to –4) and melphalan (140 mg/m2) on day -3. Graft versus host disease (GVHD) prophylaxis included a calcineurin inhibitor (tapered after day 100, and methotrexate (7.5 mg/m2 on days 1, 3 and 6) or mycophenolate mofetil. Five patients also received methylprednisone (1 mg/kg/day) between days 1 and 28; this practice was discontinued in 2007.Results: A total of 52 children (43 with SCD and 9 with thalassemia), median age 11 years (range, 10m - 20y) underwent HCT between March 2003 and July 2014. Of these, 46 received bone marrow, 5 received marrow and cord blood (CB), and 1 received CB alone. Median follow up was 35.5 months (range, 3 – 136). Forty-nine children were alive at last follow up (Figure 1); 48 were symptom-free; one CB recipient had disease recurrence following graft rejection and successfully underwent a 2nd HCT. No hepatic veno-occlusive disease was noted. Three deaths 6, 11 and 21 months post HCT were from GVHD related causes [bronchiolitis obliterans (n=1); infection with GVHD (n=2)]. The cumulative incidence of graft failure and transplant related mortality was 1.9% and 5.7% respectively. The mean time to engraftment of neutrophils (ANC >500/cu mm) and platelets (>50,000/cu mm) was 13.0 (range 5-21) and 25.9 (range 8-120) days respectively. Three patients had neurologic toxicity (seizures/PRES) post HCT. At the time of last follow up, 35 patients (67%) were complete donor chimera (>90% donor) and 16 (31%) were mixed chimera (28-89% donor). Acute GVHD (grade 1-3) was noted in 30.8%. Four had grade I, 6 had grade II, and 6 had grade III GVHD. No patient developed grade IV aGVHD. Chronic GVHD was noted in 13%. Of 43 patients that were alive without disease and >6 months post HSCT, 38 had successfully discontinued all immune suppression and maintained donor chimerism post withdrawal. Immune reconstitution was robust by the end of the first year post transplant; infectious complications (23 of 30 CMV+ recipients had reactivation) were noted primarily in the first 3 months post HSCT.Conclusions: Children with hemoglobinopathies undergoing MRD HCT tolerated this non-myeloablative preparative regimen well, with minimal early toxicities. The event-free survival rate was comparable to those achieved with myeloablative regimens. Withdrawing immunosuppression was not associated with graft loss or recurrent GVHD. GVHD complications resulted in a low mortality rate. Alternative GVHD prophylaxis may further improve event-free survival. No gonadal toxicity (determined by hormone levels) has been identified to date in 15 HCT recipients of pubertal age (>13 years). Follow up however is early and in progress to determine long-term toxicities. These results support consideration of reduced intensity conditioning regimens for HCT in children with hemoglobinopathies as an alternative to standard myeloablative regimens. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Use of High-Throughput Sequencing (HTS) of TCRß to Determine the Kinetics of Graft-Versus-Lymphoma (GVL) Effect and T-Cell Repertoire Profiles after Allogeneic Transplant

▪Introduction:While allogeneic transplant using non-myeloablative preparative regimen provides a viable alternative with low TRM, the kinetics of GVL effect and the T-cell reconstitution may differ from the myeloablative transplant. In general, the donor cell engraftment is slower using a non-myeloablative regimen and a delayed GVL effect is expected. In this study, we applied the TCRß HTS to determine (1) the kinetics of the GVL effect by quantifying the tumor cell burden prior to and after transplant and (2) the pace of the T-cell reconstitution after transplant.Method: This report included a cohort of 24 patients with advanced stage mycosis fungoides or Sézary Syndrome who underwent allogeneic transplant using a non-myeloablative regimen with total skin electron beam therapy (TSEBT, 24-36 Gy), total lymphoid irradiation (TLI, 8 Gy) and anti-thymocyte globulin (ATG). All patients received G-CSF-mobilized peripheral blood hematopoietic cells with a median donor CD34+ cell dose of 6.9 x 106/kg (range 2.0-12.4) and a median donor CD3+ cell dose of 278.1 x 106/kg (range 134.4-631.0). The unique malignant T-cell clonotype of each individual patient was identified from diagnostic blood/skin samples as the single dominant sequence by TCRß HTS. Blood samples were collected prior to and at different time points after transplant. DNA extracted from PBMC corresponding to approximately 200,000 genomes was used for HTS (Sci. Transl. Med.5:214ra171, 2013) (ImmunoSEQ, Adaptive Biotech). The tumor cell burden (including minimal residual disease, MRD) was expressed as percentage of the malignant clonotype found in the entire T-cell repertoire.Results: Prior to transplant, 21 patients (88%) had detectable disease by TCRß HTS in the blood (<1%: 10 patients, 1-5%: 3 patients, >5%: 8 patients), and 3 patients had no detectable disease in the blood. The percentage of malignant clone decreased in 19 of these 21 patients at day+30 post-transplant, and 2 patients showed stable minimal disease (0.03 and 0.30%, respectively). The reduction of tumor burden was most pronounced in patients with >5% involvement prior to transplant. In these 8 patients, the pre- and day+30 post-transplant disease burden decreased from 77.9 to 0.9%, 23.6 to 9.0%, 21.1 to 8.8%, 11.8 to 1.9%, 11.3 to 0.9%, 10.0 to 0.1%, 6.0 to 1.5% and 5.5 to 0.2%, respectively. This immediate post-transplant GVL effect was not associated with full donor T-cell engraftment (donor CD3+ >95%). The donor T-cell chimerism at day+30 was 94%, 79%, 1%, 90%, 93%, 93%, 23% and 91% for these 8 patients, respectively. Subsequently, 11 of the 24 patients achieved sustained molecular remission in the blood with a median time to achieve molecular remission of 60 days (range 30-540). Patients with full donor T-cell chimerism (n=16) had a higher chance of achieving molecular remission in the blood than those with mixed donor T-cell chimerism (69% vs 0%, p = 0.002). Of these 11 patients who achieved molecular remission in the blood, 8 also achieved molecular remission in the skin at the same time. Of the remaining 3 patients, 2 achieved molecular remission in the skin more than 4 months after achieving remission in the blood, while one patient has yet to achieve molecular remission in the skin.We then analyzed the “T-cell repertoire” at different time points post-transplant by assessing the number of unique T-cell clonotypes in each blood sample from 14 patients who had at least 1-year follow-up. While the size of the T-cell repertoire varied significantly between patients, we observed an overall upward trend within individual patients after transplant (Table). The size of T-cell repertoire did not correlate with the donor CD34+ or CD3+ cell dose in the allograft.Conclusion:By using an extremely sensitive and specific TCRß HTS, we have shown an immediate post-transplant GVL effect in which a full donor engraftment was not required, followed by a subsequent sustained GVL effect that may depend on full donor T-cell engraftment. Our results suggest a different kinetics of GVL effect in different compartments (blood vs skin). We also demonstrate continued expansion of T-cell repertoire profile after allogeneic transplant. Abstract 2473Table. The number of unique T-cell clonotypes at different time points post-transplantDay+30Day+60Day+90Day+180Day+270Day+360Median7,55010,4177,9428,40013,62820,057Range629 - 60,6441,916 - 63,6911,297 - 82,0591,572 - 66,5916,510 - 42,5651,914 - 57,358 DisclosuresNo relevant conflicts of interest to declare.

Non-Myeloablative Allogeneic Transplantation Resulting in Clinical and Molecular Remission with Low Non-Relapse Mortality (NRM) in Patients with Advanced Stage Mycosis Fungoides (MF) and Sézary Syndrome (SS)

Introduction: The majority of patients with refractory, advanced stage MF or SS have a life expectancy less than 5 years. Currently, there is no curative therapy and none of the available therapies provides a long-term remission. We have performed allogeneic transplant in 29 patients as a prospective clinical study using a novel non-myeloablative preparative regimen to provide prolonged disease control.Patient and Transplant Regimen: This cohort included 11 patients with MF and 18 patients with SS. The median age was 62 years (range 20-75). These patients were heavily treated with a median number of prior systemic therapies of 5 (range 2-13). The median time from diagnosis to transplant was 33 months (range 9-147). Five patients had stage IIB disease and 24 patients (83%) had stage IV disease (21 with IVA and 3 with IVB). All 11 patients with MF had evidence of large cell transformation. All patients had active disease at the time of preparative regimen (skin: 100%, blood: 62%, lymph node: 62%). The patients received total skin electron beam therapy (TSEBT, 24-36 Gy) as part of preparative regimen for skin disease control, immediately followed by total lymphoid irradiation (TLI, 8 Gy) and rabbit anti-thymocyte globulin (ATG). All patients received G-CSF mobilized peripheral blood hematopoietic cells from either an HLA-matched related (n=11), HLA-matched unrelated (n=13) or HLA-mismatched unrelated (n=5) donor. Cyclosporine or tacrolimus and mycophenolate mofetil were used for GVHD prophylaxis. The entire protocol required only a 5-day inpatient stay during the infusion of ATG.Results: As planned, all patients received their allograft infusion as outpatient. Patients tolerated the immediate post-transplant period extremely well. Fifteen patients required hospital admission within 100 days after transplant, with a median length of hospital stay of 4 days. The most common cause for admission was delayed ATG reaction. At day +90, full donor chimerism (donor CD3+ > 95%) was achieved in 10 patients (34%) and mixed chimerism was found in 14 patients (48%). Of these 14 patients, 9 of them subsequently achieved full donor chimerism and 1 had secondary graft rejection. Five patients (17%) had primary graft rejection (donor < 5%). Three of the 6 with graft rejection received a second transplant after experiencing disease progression. The incidence of GVHD in our study was considerably lower than reported in other studies using reduced intensity regimens. The cumulative incidence of grade II-IV acute GVHD was 21%. Five patients had grade II acute GVHD (4 skin, 1 GI) and 1 had fatal grade IV acute GVHD (GI). The cumulative incidence of extensive chronic GVHD at 1 and 2 years was 13% and 23%, respectively. One death was attributed to complications of chronic GVHD.At 3-month post transplant, 19 patients achieved a complete response and 7 had a partial response (ORR 90%). Two patients experienced disease progression immediately after transplant, and 1 patient had stable disease. The median post-transplant follow-up for the entire cohort was 22.2 months and for the surviving patients was 24.5 months. The 2-year OS and PFS were 76% (95% CI, 54–88%) and 50% (95% CI, 28–68%), respectively. Among the surviving 21 patients, 81% (n=17) were in CR at last follow-up (16 with durable CR lasting >1 year). Of the 8 deaths in this study cohort, 3 were from NRM, each due to acute GVHD, complications related to chronic GVHD, or secondary malignancy (B-cell acute lymphoblastic leukemia). The 1-year cumulative NRM was 3%. High-throughput sequencing (HTS) of TCRß CDR3 was used for minimal residual disease (MRD) monitoring (Sci. Transl. Med.5:214ra171, 2013) (ImmunoSEQ, Adaptive Biotech). Of the 24 patients assessed, 11 patients (46%) achieved molecular remission in the blood after transplant. The median time to achieve molecular remission in the blood was 60 days (range 30-540). Of these 11 patients, 10 of them also achieved molecular remission in the skin. The 2-year OS and PFS for patients who achieved molecular remission were 86% (95% CI, 34–98%) and 71% (95% CI, 26–92%), respectively.Conclusion: We have developed an effective novel preparatory regimen with low transplant related mortality for non-myeloablative allogeneic transplant in patients with advanced stage MF and SS. Using the utmost sensitive TCRß HTS method to assess MRD, we were able to demonstrate a potentially curative therapy with molecular remission in this patient population. DisclosuresNo relevant conflicts of interest to declare.

Bone Marrow Transplantation (BMT) in Myelodysplastic Syndromes: To BMT or Not to BMT—That Is the Question

Those who treat patients with myelodysplastic syndromes (MDS) have been forced to become comfortable with a rather uncomfortable truth. MDS is a bone marrow failure syndrome that represents the most commonly diagnosed myeloid malignancy and predominantly affects older adults, with a median age at diagnosis of 71 years. The only cure for MDS is hematopoietic stem-cell transplantation (HSCT). For a variety of reasons, including patient comorbidities, availability of related or matched donors, related donor comorbidities, physician and patient preference, and treatment-related adverse events, transplantation is only considered in approximately 5% of patients with MDS. Thus, even when we offer disease-modifying therapies such as azacitidine, decitabine, and lenalidomide, we are ultimately palliating 95% of our patients. Despite this, patients often perceive these drugs to have curative potential in this setting, but cure is unfortunately not possible with these agents. How do we change this paradigm? Although some factors, such as patient comorbidities and availability of donors, are largely immutable, others factors have improved, making HSCT more appealing. One such advance is reduced-intensity conditioning transplantation, which greatly reduces the toxicity of the preparative regimen without compromising efficacy, and in so doing has raised the age for potentially eligible transplantation candidates into the eighth decade. Another modifiable area is in identifying patients for whom the riskbenefit analysis for transplantation is more favorable compared with managing the disease with palliative intent. This, in turn, could affect patient and physician preferences. In the article that accompanies this editorial, Koreth et al report on a Markov decision analysis exploring the role of reduced-intensity allogeneic HSCT in older patients with MDS. This statistical technique relies on assumptions, which themselves are based on best estimates of outcome given in previously published studies, to play out scenarios of what would happen in real life to a given patient if he or she decided to undergo HSCT early, at or near diagnosis, or instead to pursue supportive care, growth factor, or disease-modifying therapy. Although this approach is not perfect, it does allow for sensitivity analyses in which assumptions can be changed to see if the same conclusion holds, and it is the best substitute available in the absence of prospective, randomized studies. This is also not the first time some of these investigators have tackled this question, or this methodology. In 2004, Cutler et al published a decision analysis of patients with MDS treated with myeloablative conditioning transplantation. Given this conditioning regimen, patients were younger (with a median age of 40.4 years), and given the timing at which this analysis was conducted, a paucity of individual patient data were available to appropriately reflect nontransplantation treatment approaches. So, although the results of the study by Cutler et al make clinical sense, namely, that early transplantation provides maximal quality-adjusted survival in higher-risk patients with MDS (those falling into intermediate-2 and high-risk categories of the International Prognostic Scoring System [IPSS]), these conclusions have always given treating doctors pause because the participants did not reflect the full spectrum of patients with MDS who are seen in everyday clinical practice. The analysis by Koreth et al addresses these shortcomings. Now, given the nonmyeloablative preparative regimen, the median age of the 132 patients undergoing transplantation gleaned from the Center for International Blood and Marrow Transplant Research, DanaFarber Cancer Institute, and Fred Hutchinson Cancer Research Center data sets is 64 years—closer to what we see in clinic. Patients who did not undergo transplantation included 132 with lower-risk disease (IPSS low and intermediate-1) receiving best supportive care; 91 anemic or transfusion-dependent patients receiving erythropoiesisstimulating agents; and 164 higher-risk patients with MDS receiving azacitidine or decitabine. Patients being treated with lenalidomide, immunosuppressive approaches, or drug combinations were not included. Primary end points of the model were life expectancy (LE) and quality-adjusted life expectancy, an end point adjusted for quality of life, the values of which were derived from studies in which patients may not reflect those included in the current analysis. The authors tried to keep the assumptions used in an already complicated model to a minimum, and in so doing ignored some real-life scenarios, such as a patient initially in the nontransplantation arm deciding at a later time to undergo transplantation. That being said, the results suggest that for lower-risk patients with MDS, median LE for those avoiding HSCT was approximately double that of those undergoing HSCT, at 77 versus 38 months. For higher-risk patients, a more modest advantage was seen for early HSCT, with a median LE of 36 months, versus 28 months for nontransplantation approaches. Interestingly, in the JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 31 NUMBER 21 JULY 2

Sequential Treatment After Allogeneic Stem Cell Transplantation for Chronic Myelogenous Leukemia.

AbstractAbstract 3129 BackgroundTyrosine kinase inhibitors (TKI) have revolutionized treatment of chronic myeloid leukemia (CML), nonetheless as seen in follow-up of the IRIS study, almost 30% of patients discontinued imatinib due to inadequate response or intolerance. Allogeneic stem cell transplant (ASCT) remains the only effective treatment to produce durable complete remissions in CML; curative effect is largely derived from immune graft-versus-leukemia (GVL) effect mediated by alloreactive donor T cells reacting against residual host malignant cells. We evaluated sequential therapy after a nonmyeloablative preparative regimen, designed to reduce risks of toxicity, graft-versus-host disease (GVHD) and treatment related mortality. Patients with residual CML 3 months post ASCT received imatinib and those without a complete molecular remission after an additional 3 months received donor lymphocyte infusions (DLI).Patients and Methods Objective:To increase frequency of achievement of complete molecular response (CMolR) following reduced intensity ASCT. Eligibility:CML in chronic phase (CP) with failure to respond/intolerance to one or more TKIs. Patients received a reduced intensity preparative regimen involving fludarabine 40 mg/m2 × 4 days, busulfan 130 mg/m2 × 2 days, and antithymocyte globulin (Thymoglobulin) 2.5 mg/kg daily × 3 days followed by ASCT from an HLA identical or one antigen mismatched related or unrelated donor. GVHD prophylaxis was tacrolimus and methotrexate (5 mg/m2 on SCT days 1, 3, 6 and 11). Patients who had engraftment but residual disease by quantitative PCR for bcr-abl rearrangement at 3 months post ASCT received imatinib treatment with dose titrated to hematologic toxicity. Those with residual disease 6 months post ASCT and no active GVHD received DLI. Patients were treated between 4/2003 - 6/2008; median follow up was 74 months (4–99). Outcome of interest was progression free survival (PFS) and overall survival (OS), estimated using Kaplan-Meier estimate, and survival comparisons between groups was by log rank test. ResultsPatient characteristics summarized in Table 1; response analysis in Table 2. 41 patients were entered on study, all were previously treated with a TKI; at time of ASCT, 10 were in first chronic phase (CP1), 8 had isolated clonal evolution (CE) and 23 had a history of advanced CML (>CP1, or accelerated phase). One patient died within 100 days post HSCT and 3 had graft failure; one required a second transplant; 2 had autologous recovery with CMolR and are both alive. At 3 months, all patients in CP1 or with CE (18/44%) obtained complete cytogenetic response (CCgR); 15(36%) of 23 advanced patients achieved CCgR. CMolR was attained by 8 patients, 4 in CP1. No one with minimal residual disease achieved a CMolR without intervention. 22 patients received treatment with TKIs post ASCT; and of those 9 later received DLI. CMolR was achieved in 12 of 22 patients who had molecular progression post ASCT. 26 patients are alive at last follow up and 15 deaths were due to, relapsed leukemia (9), GVHD (3), and infection (3), respectively. ConclusionIn conclusion, sequential therapy including reduced intensity HSCT, post transplant treatment with TKI, and donor lymphocyte infusion was associated with a low rate of treatment related mortality. This approach is capable of prolonged cytogenetic and molecular complete remissions and survival. Disease status at time of transplant was the most important prognostic factor. This is an effective option for patients in chronic phase who have failed to respond optimally to TKI based treatment.Table 1- Patient CharacteristicsN (%)N (%)Age at TP, med (range)42 (14–69)Median f/up in alive, mo74 (4–99)Age ≥50 yr10 (76)% OS60% (42–74)≤5031 (24)% PFS56% (38–70)Donor TypeMRD21/51%Disease statusMUD19/46%CP110/24%Ag MM rel1/2%CP214/34%TKI prior to transplantN (%)≥CP35/12%Imatinib33/80%AP13/7%Dasatinib6/15%AP21/2%Nilotinib1/2%CE8/20%Bafetinib1/2%Table 2- Responses After Sequential Therapy Protocoln= 41Response to prep regimen at 3 moMolecular CR to imatinib (n=22)Molecular CR to DLI (n=9)Alive/CCgR/CMolRRelapse/DeadCP1 n=10CCgR = 10 (100%)1 of 41 of 210/10/50/0CMolR = 4 (40%)CP2/CE/AP1 n=25CCgR = 21 (84%)4 of 175 of 717/16/118/10CMolR= 3 (12%)AP2/≥CP3 n=6CCgR = 2 (33%)1 of 1none1/1/15/5CMolR = 1 (17%)Disease statusOSpPFSpN=15 diedN=17CP11000.0200.01CP2/AP1/CE25912≥CP3/AP2655 [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Factors Predictive of Relapse of Hematologic Malignancies in Pediatric Patients Post Allogeneic Hematopoietic Cell Transplantation

AbstractAbstract 4206 Background:Relapse is the primary cause of treatment failure post alloHCT. We sought to identify risk factors that predict relapse of hematologic malignancies post-alloHCT to identify those at highest risk of relapse and help guide who may benefit from novel approaches to reduce relapse risk. Design:This was a single institution, retrospective cohort study of children with acute lymphoblastic leukemia, acute myelogenous leukemia, mixed phenotypic acute leukemia or myelodysplastic syndrome who had undergone alloHCT between 1/1/2003 and 12/31/2010. Relapse was defined as any evidence of increasing disease post-alloHCT, including minimal residual disease (MRD). Relapse-free survival (RFS) and associations with various characteristics were determined by the Kaplan-Meier method and log-rank test. The Cox proportional hazards model was used to identify factors that may jointly associate with RFS. Results:40 of 93 patients (43%) undergoing alloHCT experienced relapse at a median of 144 days (range 1 day – 58 months) post-HCT. Univariate actuarial analysis demonstrated that Black race (Figure 1), high white blood cell (WBC) count at diagnosis, central nervous system (CNS) disease at diagnosis (Figure 2), short first complete remission (CR1) duration (limited to those attaining CR1 with subsequent pre-HCT relapse), greater number of regimens given to induce remission, poorer performance status, non-myeloablative (NMA) preparative regimen, lack of remission and MRD pre-HCT were associated with higher relapse probability (Table 1). These factors were considered for inclusion in a Cox model; CNS disease at diagnosis (p=0.009), lack of morphologic remission (p=0.01) and a NMA HCT (p=0.04) were factors independently associated with worse RFS. 84 patients surviving to day 45 without relapse were included in a subset analysis to allow for incorporation of post-alloHCT factors that may modify relapse risk (i.e., graft-versus-host disease). When factors were considered jointly, only WBC at diagnosis was significantly associated with RFS. For patients in a morphologic remission who underwent a myeloablative HCT, MRD detection approximately doubled relapse risk. (Table 2). Conclusion:The association of CNS disease at diagnosis with higher post-HCT relapse risk has not previously been reported. As a sanctuary site, the CNS may be less amenable to an allogeneic effect and CNS involvement might reflect higher-risk disease. Those with CNS disease may benefit from earlier or more intensive CNS-directed therapy to reduce relapse risk. The association of black race with increased relapse risk in the univariate analysis is also notable. For these patients, increased utilization of alternative donor sources or distinct biological differences may lead to higher relapse risk. Validation of these risk factors in a larger population and development of a prognostic score to identify those at highest risk of relapse is planned with possible prospective use of this prognostic tool in the development of relapse prevention trials.Table 1Pre-HCT Patient Characteristics Associated with Post-HCT RelapseAll (n)Patients without relapse during follow-up (n)Patients with relapse during follow-up (n)Log-rank p-value for comparison of Relapse Free SurvivalTotal (n)935340—RaceNon-black7647290.03Black17611DiseaseAcute lymphoblastic leukemia341816Not significantAcute myelogenous leukemia412318Mixed phenotypic acute leukemia1064Myelodysplastic syndrome862At DiagnosisWhite Blood Cell count>65,000187110.04< 65,000543420Central nervous system diseaseYes2410140.03No613922Duration of first complete remission*> 450 days191270.06< 450 days19613# of induction regimens given to induce remission0 (MDS only)7610.0212719823618183+231013At HCTMorphologic RemissionYes7444300.006No1138Minimal residual disease>0.01%3414200.015< 0.01%503218Performance status80–100%8451330.0240–70%826HCT TypeMyeloablative7949300.004Non-Myeloablative14410*Limited to those attaining a CR1 with subsequent pre-HCT relapse.Table 2:Relapse rates, by MRD, for those in a complete remission undergoing a myeloablative HCTDiseaseMRD >0.01%Total (n)Relapse (n)Relapse RatesAcute lymphoblastic leukemiaNo20735%Yes11764%Acute myelogenous leukemiaNo16319%Yes11436%Mixed phenotype acute leukemiaNo8338%Yes100% [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Haploidentical Transplantation Using T-Cell Replete Peripheral Blood Stem Cells and Myeloablative Conditioning in Patients with High-Risk Hematologic Malignancies Who Lack Conventional Donors Is Well Tolerated and Produces Excellent Relapse-Free Survival: Results of A Prospective Phase II Trial

Abstract 889▪▪This icon denotes a clinically relevant abstract Introduction:Haploidentical hematopoietic stem cell transplantation (HSCT) provides an opportunity for nearly all patients to benefit from HSCT when a human leukocyte antigen (HLA) genotypically matched donor is not available. Initial approaches to mismatched allografting using ex-vivo T-cell depletion and intense preparative regimens were associated with high rates of graft rejection, severe graft-versus-host disease (GVHD) and infectious complications, resulting in an unacceptable treatment-related morbidity and mortality. More promising outcomes have been recently demonstrated by a new approach to haploidentical transplantation, utilizing a nonmyeloablative preparative regimen, followed by a T cell-replete bone marrow infusion and post-transplantation immunosuppression with high dose Cyclophosphamide (Cy), tacrolimus, and mycophenolate mofetil (MMF). However, relapse represents the major cause of treatment failure in these patients, particularly with high-risk myeloid malignancies. Methods:In order to decrease relapse risk in patients with high-risk malignancies, we initiated a trial between January 2009 and March 2011, of haploidentical allografting using a myeloablative preparative regimen and peripheral blood stem cells (PBSC) instead of bone marrow as the graft source. Eligibility was limited to patients perceived to be at prohibitively high risk of relapse following nonmyeloablative haploidentical BMT. Initial conditioning (n=5) consisted of Fludarabine 30 mg/m2 on days −7 to −2, IV Busulfan 130 mg/m2 on days −7 to −4, and Cy 14.5 mg/kg on days −3 and −2 followed by an unmanipulated PBSC infusion in all patients. In response to increased rates of mucositis, fludarabine and busulfan doses were decreased by 30% and 15%, respectively, in subsequent patients. Post-grafting immunosuppression consisted of Cy 50mg/kg/day on days 3 and 4, MMF, and tacrolimus. Results:A total of twenty patients were enrolled in the study: median age 44 years (25–56); diagnoses AML=12, ALL= 2, HD=1, CML=3, CLL=1, NHL=1; allograft from 5/10 locus matched (n=14), 6/10 locus matched (n=2), 7/10 locus matched (n=3), or 8/10 locus matched (n=1). CIBMTR disease risk-high risk =7 (35%), intermediate risk = 4 (20%) or low risk = 9 (45%). Of the 9 low risk patients, seven were cytogenetically poor-risk AML and/or required ≥2 induction cycles to induce complete response. Donor engraftment occurred in all 20 patients, with a median time to neutrophil and platelet recovery of 16 and 27 days, respectively. All evaluable patients achieved complete donor T cell and myeloid chimerism by Day +30. The cumulative incidence of grades II–IV and grades III–IV aGVHD was 30% and 20%, respectively. The cumulative incidence of cGVHD at one year was 42%. Non-relapse mortality (NRM) at 100 days and 1 yr was 10% for all patients and 0% for low-risk patients. Non-infectious fever (median tmax 103.9; 101.2–106.8), possibly related to cytokine release from proliferating alloreactive cells, developed in 90% of patients within a median of 2.5 days (1–5) of transplant and resolved by day 6 (5-7) following post-transplant Cy. BK virus-associated cystitis occurred in 75% of patients, and was severe (requiring hospital admission for bladder irrigation and/or pain management) in 35%. Other severe infections were not seen at increased frequency compared to conventional donor myeloablative transplants at our center. With a median follow-up of 14 months, the estimated 1 year overall and disease-free survival was 74% and 51%, respectively for all patients; 100% and 76%, respectively for low-risk patients. Conclusion:HLA haploidentical HSCT using this myeloablative regimen with T-cell replete PBSC and post-transplant Cy is associated with excellent rates of engraftment, GVHD, NRM and DFS, it is therefore a valid option in patients with high-risk malignancies who lack timely access to a conventional donor. Disclosures:Sizemore:Otsuka America Pharmaceuticals, Inc.: Research Funding. Bashey:Otsuka America Pharmaceuticals, Inc.: Research Funding. Sanacore:Otsuka America Pharmaceuticals, Inc.: Research Funding. Manion:Otsuka America Pharmaceuticals, Inc.: Research Funding. Holland:Otsuka America Pharmaceuticals, Inc.: Research Funding. Morris:Otsuka America Pharmaceuticals, Inc.: Research Funding. Brown:Otsuka America Pharmaceuticals, Inc.: Research Funding. Solomon:Otsuka America Pharmaceuticals, Inc.: Research Funding.

Reduced-Intensity Allogeneic Hematopoietic Transplantation Should Be Considered a Standard of Care for Older Patients with Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is primarily a disease of older people with a median age greater than 65 years. The treatment of AML in elderly patients remains a major challenge. Older patients are more likely to have high-risk cytogenetic abnormalities, and age itself confers a poor prognosis. There has been little progress with standard forms of chemotherapy [1-3]. Allogeneic stem cell transplantation (SCT) were originally developed as a means of delivering high-dose myeloablative chemotherapy or radiation with the transplant to provide hematologic recovery after the myeloablative therapy [4]. This approach is associated with considerable toxicity, and could only be performed in relatively young patients in excellent general medical condition. We have come to appreciate that much of the benefit is derived from the graft-versus-leukemia effect mediated by donor immune cells [5,6]. This realization has supported the development of reduced-intensity or nonmyeloablative preparative regimens involving lower doses of chemotherapy and/or total-body radiation, which are sufficiently immunosuppressive to prevent rejection and allow development of the graft-versus-leukemia effect [7-10]. These reduced-intensity regimens allow treatment of older or medically infirm patients who were not previously eligible for allogeneic stem cell transplantation [11]. Reduced-intensity regimens may be associated with a higher risk of relapse compared with myeloablative conditioning, but leukemia-free survival is similar in most studies [12,13]. Patients up to age 75 years have been treated with this approach. Similar results are reported with matched related or unrelated donors [14,15]. A number of studies have shown promising results of reduced-intensity transplants in patients with AML. In this issue, Farag et al. [16] evaluate the results of treatment for patients age 60 to 70 years, comparing the results of reduced-intensity allogeneic transplantations reported to the Center for International Blood and Marrow Transplant Research with patients receiving standard chemotherapy on Cancer and Leukemia Group B protocols. The 2 groups had similar patients characteristics and prognostic factors. The transplant recipients were slightly younger than the chemotherapy group. Patients receiving allogeneic HCT had a significantly lower risk of relapse (32% versus 81% at 3 years; P < .001), and longer leukemia-free survival (32% versus 15% at 3 years; P < .001). Allogeneic stem cell transplantation is a high-risk procedure, and as expected, there was a higher risk of nonrelapse mortality at 3 years (36% versus 4%; P < .001). Overall survival was 37% versus 25% at 3 years (P = .08). One limitation of this type of analysis is the effect of patient selection. Older patients undergoing SCT are selected to be in good enough medical condition to undergo SCT and are a self-selected, highly motivated group of patients. Allogeneic SCT involves a major commitment on the part of the patient, requiring close medical monitoring for at least several months. It frequently requires patients and their caregivers to relocate temporarily to another city to be near the transplant center. Allogeneic hematopoietic transplantation is not a feasible or desirable choice for many elderly patients. These considerations make it almost impossible to conduct a prospective randomized study. However, this and other studies demonstrate that allogeneic SCT provides durable complete remission in a high fraction of older patients, and the reported results consistently compare favorably to those achieved with alternative conventional treatments [17]. Age alone should not be considered a contraindication to allogeneic SCT for AML [15]. Allogeneic hematopoietic transplantation using a reduced-intensity regimen should be considered an effective treatment option and an established standard of care for older patients with AML.

Preclinical and clinical studies on the induction of renal allograft tolerance through transient mixed chimerism

The present review updates the current status of research for induction of tolerance through a mixed chimerism approach in nonhuman primates and humans. Allograft tolerance has been successfully achieved with a nonmyeloablative conditioning regimen and donor bone marrow transplantation in human leukocyte antigen (HLA)-matched and mismatched kidney transplantation. In HLA-matched kidney transplantation, persistent mixed chimerism and renal allograft tolerance has been achieved in some patients. In HLA-mismatched combinations, induction of persistent mixed chimerism has not been achieved using a nonmyeloablative preparative regimen. Nevertheless, the transient mixed chimerism that has been achieved has resulted in long-term renal allograft tolerance in the majority of patients. Recent preclinical studies have demonstrated that the presence of heterologous memory T-cell responses observed in primates, but not in rodents, may be a major barrier for induction of durable chimerism and tolerance in primates. Strategies to overcome such memory T-cell responses may, therefore, be of great value in the development of reliable protocols for clinical tolerance induction. Induction of tolerance in clinical kidney transplantation has been achieved via mixed chimerism approaches. Improvements in the consistency and safety of tolerance induction and extension of successful protocols to other organs and to organs from deceased donors will all be among the next steps in bringing tolerance to a wider range of clinical applications.

Non-myeloablative conditioning with allogeneic hematopoietic cell transplantation for the treatment of high-risk acute lymphoblastic leukemia

Allogeneic hematopoietic cell transplantation is a potentially curative treatment for patients with acute lymphoblastic leukemia. However, the majority of older adults with acute lymphoblastic leukemia are not candidates for myeloablative conditioning regimens. A non-myeloablative preparative regimen is a reasonable treatment option for this group. We sought to determine the outcome of non-myeloablative conditioning and allogeneic transplantation in patients with high-risk acute lymphoblastic leukemia. Fifty-one patients (median age 56 years) underwent allogeneic hematopoietic cell transplantation from sibling or unrelated donors after fludarabine and 2 Gray total body irradiation. Twenty-five patients had Philadelphia chromosome-positive acute lymphoblastic leukemia. Eighteen of these patients received post-grafting imatinib. With a median follow-up of 43 months, the 3-year overall survival was 34%. The 3-year relapse/progression and non-relapse mortality rates were 40% and 28%, respectively. The cumulative incidences of grades II and III-IV acute graft-versus-host disease were 53% and 6%, respectively. The cumulative incidence of chronic graft-versus-host disease was 44%. Hematopoietic cell transplantation in first complete remission and post-grafting imatinib were associated with improved survival (P=0.005 and P=0.03, respectively). Three-year overall survival rates for patients with Philadelphia-negative acute lymphoblastic leukemia in first remission and beyond first remission were 52% and 8%, respectively. For patients with Philadelphia chromosome-positive acute lymphoblastic leukemia in first remission who received post-grafting imatinib, the 3-year overall survival rate was 62%; for the subgroup without evidence of minimal residual disease at transplantation, the overall survival was 73%. For patients with high-risk acute lymphoblastic leukemia in first complete remission, non-myeloablative conditioning and allogeneic hematopoietic cell transplantation, with post-grafting imatinib for Philadelphia chromosome-positive disease, can result in favorable long-term survival.