ALBERT

Description: Background: In acute myeloid leukemia (AML), detection of minimal residual disease (MRD) by flow cytometry is an adverse prognostic factor besides pre-treatment risk classifications, including cytogenetic and molecular aberrations. High dimensional multiparameter flow cytometry (MPFC) offers improved sensitivity and specificity, however manual analysis is increasingly challenging. In this study, we explore the value of the recently proposed viSNE algorithm to quantify MRD levels in patients with AML achieving complete remission (CR) after intensive induction chemotherapy. Methods: Bone marrow samples from patients with AML (excluding patients with acute promyelocytic leukemia) were analyzed by 8-10 MPFC using a NAVIOS flow cytometer (Beckman Coulter, Brea, CA, USA). Only patients achieving a CR or CR with incomplete blood count recovery (CRi) post-induction were included in this analysis. Manual gating of MRD flow data was performed as described previously (Köhnke et al., Leukemia 2014) using a cutoff for MRD positivity of 0.1%. The viSNE algorithm was performed as described previously (Amir et al., Nat. Biotech. 2013) and MRD positivity was defined as the presence of a distinct cluster of 〉100 cells which consisted of 〉90% patient cells. Kaplan-Meier estimator and log-rank test as well as Cox's proportional hazards regression model were used to analyze survival data. Results: Post-induction flow cytometry and clinical data of 38 patients with AML achieving CR (n=34) or CRi (n=4) were available for analysis (median age 53 years; de-novo AML n=32, tAML n=1, sAML n=5). Most patients belonged to the intermediate cytogenetic risk group (MRC favorable n=5, intermediate n=22, adverse n=11). 19/38 patients were MRD positive post-induction by manual gating. 12/19 patients deemed MRD positive relapsed, whereas 3/19 patients deemed MRD negative relapsed. Therefore, MRD positivity by manual gating correlated with reduced relapse free survival (median RFS for MRD positive patients: 7.5 months vs. median not reached for MRD negative patients, log-rank test p=0.017). For overall survival (OS), no significant impact of MRD positivity could be detected so far (p=0.3), however follow-up was short (median follow-up 9.3 months). MRD positivity by manual gating remained an independent risk factor for RFS (HR 4.8, p=0.021) when compared to genetic risk and age. MRD positivity by viSNE clustering was seen in 19/38 patients. 10/19 patients deemed MRD positive by viSNE relapsed, while 5/19 deemed MRD negative by viSNE experienced a relapse. This resulted in a trend towards shorter RFS for MRD positivity by viSNE (median RFS 9.9 months vs. 19.0 months for MRD negative patients, p=0.185). Among the patients deemed MRD positive by viSNE who did not relapse, i.e. false-positive patients, follow-up was very short (

Description: Hematopoietic stem cell transplantation is a potent curative treatment option for patients suffering from high-risk AML and MDS. However, not in all of our patients a suitable HLA-matched donor could be identified in time. To evaluate the feasibility and outcome of T-cell-replete (TCR) HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) utilizing post-transplantation high-dose cyclophosphamide (PTCY) in the context of sequential therapy in patients with high-risk, relapsed/refractory and progressive AML and MDS, we retrospectively analyzed the course of 64 patients (AML n=61, MDS n=3; median age: 50 years; male n=30) transplanted between 2009 and 2015 at our center. Disease was advanced in 55 patients including 24 patients with relapse after a first allogeneic transplantation. 54 patients presented with active disease at time of haplo-HSCT. Donors (median age: 38 years; male n=30) were fully HLA-haplotype mismatched (5/10 HLA-loci) in 48 cases (77%). All patients received sequential therapy prior to haplo-HSCT combining cytoreductive chemotherapy (clofarabine n=34; FLAMSA n=25; FLAG-Ida n=2; others n=3) and reduced-intensity conditioning (RIC) which was started after three days of rest thereafter. Conditioning was drug-based in 42 patients receiving fludarabine, cyclophosphamide (CY) and melphalan (110 mg/m2) while it was TBI-based in the others (n=22) consisting of fludarabine and CY plus either 4 (n=20) or 2 Gy TBI (n=2). Post-grafting immunosuppression was high-dose CY given on day + 3 and +4, tacrolimus and mycophenolate mofetil (both started on day +5) in all patients. Unstimulated bone marrow was the graft source in 37 patients. One graft rejection was observed after conditioning with 2 Gy TBI. Neutrophil/platelet engraftment was achieved in 49/58 evaluable patients at a median of 16 (range: 14-27) and 20 (range: 13-74) days, respectively. Acute GvHD grade II-IV occurred in 19 patients (30 %) while it was severe (grade III-IV) in only 3 (5 %). Chronic GvHD was most frequently mild (n=9) to moderate (n=8); one severe chronic GvHD occurred. Severe (grade III-IV) mucositis, hemorrhagic cystitis and hand-foot syndrome/rash were observed in 10, 5 and 2 patients, respectively; no patient developed VOD. Kidney failure requiring hemodialysis occurred in 7 patients. CMV reactivation was observed in 28 of 47 patients at risk (59 %) and EBV in 3, while only one patient developed CMV disease (pneumonia) and no patient developed PTLD. Probable or proven (n=2) invasive aspergillosis was diagnosed in 10 patients. One-year non-relapse mortality was 27.5 % (95% CI 17-41). After a median follow up of 21 months (range: 3-64), estimated one-year overall survival (OS) was 55 % (95 % CI 41-66), and one-year disease-free survival (DFS) was 43 % (95 % CI 26-51). At two-years after sequential haplo-HSCT OS and DFS were both 39 % (95 % CI 26-51). In summary, sequential therapy in the setting of RIC-TCR haplo-HSCT using PTCY is well tolerated with low rates of GvHD and acceptable NRM in patients with high-risk AML and MDS, while providing an effective anti-leukemic activity in advanced disease. Results are comparable to data of a historical cohort of patients with high-risk AML and MDS undergoing sequential therapy using the FLAMSA-RIC protocol in a HLA-matched setting, as reported by our group previously. Thus, we suggest that donor availability can be expanded in patients with high-risk and advanced AML/MDS who lack a conventional donor or need promptly access to a donor due to aggressive disease. Disclosures Hausmann: Sanofi-Aventis: Other: advisory board. Tischer:Sanofi-Aventis: Other: advisory board. Off Label Use: clofarabine in adults; efficacy is shown in myeloid blasts;.