Abstract: In patients with hematological malignancies, bronchoalveolar lavage fluid (BALF) specimens are commonly used for the diagnosis of mold infections. However, it is not clear whether the cell pellet (P) or the supernatant fraction (S) of the BALF specimen is optimal for molecular diagnostic testing. Thus, 99 BALF specimens were collected from 96 hematology patients with or without allogeneic hematopoietic stem cell transplant. The cell pellets and supernatants were processed alone and in combination (S/P) for testing by two fungus-specific real-time PCR assays compliant with international recommendations. The results achieved with S/P were revealed to be superior in comparison to those achieved with S and P alone, with the use of each single fraction showing a reduced sensitivity for the detection of Aspergillus DNA (82% and 43% for S and P, respectively). In 57% of the samples, testing of the combination of S and P generated a lower quantification cycle value than testing of S or P alone. Molds would have been missed in 5 and 16 out of 28 samples if only S or P, respectively, was analyzed. No sample was positive by testing of S or P only. Similar results were obtained for the detection of Mucorales DNA in BALF specimens (reduced sensitivity of 67% and 50% for S and P, respectively). Study patients were categorized according to the current European Organization for the Research and Treatment of Cancer/Mycoses Study Group classification for invasive fungal disease (IFD), revealing that 35 patients had proven/probable IFD (36%), 47 patients had possible IFD (49%), and 14 patients had undetermined IFD (15%).

Abstract: Abstract 1637 Blinatumomab (MT103) is a single-chain bispecific antibody construct with specificity for CD19 and CD3 belonging to the class of bispecific T cell engager (BiTE®). A phase I trial with indolent and mantle cell lymphoma patients established a maximal tolerable dose (MTD) at 60 μg/m2/d. The trial was subsequently amended to evaluate blinatumomab in patients with diffuse large B cell lymphoma (DLBCL). Patients were treated by 4–8-week continuous i.v. administration with the following dosing regimen: first week at 5 μg/m2/d, second week at 15 μg/m2/d and for the remaining treatment period at 60 μg/m2/d. Two cohorts each with 6 DLBCL patients were enrolled. The two cohorts solely differed by the dose and schedule of corticosteroid medication administered at the beginning of blinatumomab infusion for mitigation of adverse events. In the first cohort 100 mg prednisolone was applied 1 hour prior to start; and in the second cohort patients received dexamethasone on days 1, 2, and 3. Three sequential patients received dexamethasone also 6–12 hours prior to start of infusion. Out of the twelve patients, 5 were male and 7 female. The median age was 57 years (range from 26 to 78 years). Patients had received a median of 4 prior regimens (range from 2–6). All patients had been exposed to rituximab. Eight of the 12 patients had undergone autologous stem cell transplantation (ASCT). International prognostic index (IPI) at screening ranged from 1 to 3 with a median of 2. The most common clinical adverse events (AEs) regardless of causality ( 〉 30%) were pyrexia (81.8%), fatigue (54.5%), constipation (36.4%), headache (36.4%), tremor (36.4%) and weight increase (36.4%). The most frequent laboratory AEs regardless of causality ( 〉 30%) were hyperglycemia (63.6%), lymphopenia (54.5%), C-reactive protein increase (45.5%), gamma-glutamyltransferase increase (45.5%) and thrombocytopenia (36.4%). Most AEs occurred early and were reversible. Four of 12 patients discontinued infusion due to fully reversible CNS events, 2 of which qualified as dose limiting toxicities (DLTs). Although just one DLT (reversible CNS event grade 3) occurred in the prednisolone cohort, a further cohort applying prophylactic dexamethasone was opened to optimize management of CNS events. A further refinement of the dexamethasone schedule, starting longer time prior to start of blinatumomab, was introduced after one early patient in the cohort receiving dexamethasone had experienced a reversible CNS event leading to discontinuation. All three patients treated in this manner completed the first blinatumomab cycle without discontinuations. Only one showed a grade 1 tremor, and no other CNS AEs were reported in these three patients. Two of 12 patients were not exposed to 60 μg/m2/d due to early discontinuations and 1 patient is too early in treatment for response evaluation. Five out of the remaining 9 evaluable patients (56%) showed objective clinical responses (4 CR/CRu; 1 PR). Three out of the 5 patients with CR/CRu or PR had prior ASCT. Two patients achieved objective responses (1 CR, 1 PR) despite of discontinuation at 60 μg/m2/d. The median response duration is +182 days (longest current duration +428 days), with 4 out of 5 responses still ongoing. Further evaluation of the last cohort will refine the recommended phase II dose, and the intensity and timing of dexamethasone comedication. The observation of lasting CRs after blinatumomab monotherapy in DLBCL patients is promising and warrants further exploration in a phase II study. Disclosures: Krause: Micromet: Research Funding. Mackensen:Micromet Inc.: Research Funding. Topp:Micromet: Consultancy, Honoraria. Scheele:Micromet Inc.: Employment, Equity Ownership, Patents & Royalties. Nagorsen:Micromet Inc.: Employment, Equity Ownership, Patents & Royalties. Zugmaier:Micromet: Employment. Degenhard:Micromet Inc: Employment. Schmidt:Micromet AG: Employment. Kufer:Micromet Inc: Employment, Equity Ownership. Libicher:Micromet Inc.: Consultancy, Honoraria. Bargou:Micromet: Consultancy, Honoraria.

Abstract: Background: Trisomy 4 is a recurrent but rare cytogenetic abnormality reported in patients with acute myeloid leukemia (AML). The prognostic significance of this abnormality in AML patients is not clear. Prognosis of AML patients with trisomy 4 seems to be poor as compared to that of patients with intermediate-risk cytogenetics. Allogeneic hematopoietic stem cell transplantation (allo-HCT) may improve survival if applied early in first complete remission (CR). However, neither prospective clinical nor larger retrospective cohort studies are available to support these results from small series. Aims: To characterize AML patients with trisomy 4 and compare outcomes according to different treatment strategies. Methods: We retrospectively studied 123 AML patients with trisomy 4 (median age at diagnosis, 58 years; range, 16-76 years) treated between 2000 and 2019 within 2 large study groups. Standard statistical methods were applied. Results: Median white blood cell count at diagnosis was 4.8/nl (range, 0.4-255/nl) and platelets 46/nl (range, 2-330/nl). Type of AML was de novo in 97 (79%), secondary after myelodysplastic syndrome/myeloproliferative neoplasm in 18 (15%), and therapy-related in 8 (6%) patients. Sixty-two (50%) patients were female. Cytogenetic analysis revealed trisomy 4 as the sole abnormality in 28 (23%), additional abnormalities in 95 (77%) patients, most frequently ≥3 (n=66) abnormalities, trisomy 8 (n=41), karyotypes characterized by trisomies only (n=21) and t(8;21) or inv(16) (CBF; n=10). A total of 98 patients (80%) had NPM1 and FLT3-ITD mutation testing. Of those, 21 (21%) and 15 (15%) harbored NPM1 and FLT3-ITD mutations. Only 2 (3%) of 72 patients were CEBPA double mutated. Data on response to intensive anthracycline-based induction therapy were available in 117 patients. Early death rate was 5% (n=6). CR was achieved in 68% (n=79) with 22 (19%) requiring an intensive salvage treatment cycle. Notably, patients with trisomy 4 as sole abnormality had a CR rate of 89% (n=25/28). There was no difference in the CR rate in FLT3-ITD positive (n=10/15) as compared to FLT3 wild type (n=56/83) patients (67% each, P=0.99). Univariable analysis revealed trisomy 4 as sole abnormality (OR, 5.76; P=0.007) and NPM1 (OR, 12.08; P=0.02) as favorable factors. An allo-HCT was performed in 40 (34%) patients, of whom 19 patients were transplanted in first CR after induction therapy. Nine patients achieved CR after salvage chemotherapy and went on to allo-HCT; another 12 patients received allo-HCT with active disease. Type of donor was matched-related in 8, matched-unrelated in 30, and unknown in 2 of the 40 patients, respectively. Median follow-up of the intensively treated cohort was 73 months (95%-CI, 36-91 months). Five-year overall survival (OS) and relapse-free survival (RFS) were 31% (95%-CI, 23-42%) and 27% (95%-CI, 18-42%). OS rates were significantly higher in patients with CBF leukemia or patients with trisomy 4 as compared to all other abnormalities (Figure 1; P & lt;0.001). Cox regression analysis on OS revealed CBF/CEBPA (HR, 0.75; P=0.02) and trisomy 4 as sole abnormality (HR, 0.63; P=0.04) as favorable factors; age with a difference of ten years was an in trend adverse factor (HR, 1.15; P=0.06; not significant: NPM1, FLT3-ITD, complex karyotype with ≥3 abnormalities). There was no difference on OS if patients proceeded to allo-HCT in CR1 or with active disease (P=0.8). Five-year RFS was 26% (95%-CI, 14-50%) in patients proceeding to allo-HCT after induction therapy (n=40), as compared to 28% (95%-CI, 17-46%; P=0.99) in those who received consolidation chemotherapy (n=49). Conclusions: Clinically, patients with trisomy 4 are very heterogeneous in particular with respect to cytogenetic and molecular abnormalities. In our cohort, patients with trisomy 4 as a sole abnormality had a high CR rate and favorable clinical outcome. In the total cohort, allo-HCT did not improve RFS. Figure 1 Figure 1. Disclosures Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Haenel: Takeda: Consultancy, Honoraria; Bayer Vital: Honoraria; Jazz: Consultancy, Honoraria; GSK: Consultancy; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Crysandt: Incyte: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees. Fransecky: Medac: Honoraria; Amgen: Honoraria; Abbvie: Honoraria, Research Funding; Novartis: Honoraria; Takeda: Honoraria. Martinez-Lopez: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. Platzbecker: AbbVie: Honoraria; Celgene/BMS: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Geron: Honoraria; Takeda: Honoraria. Baldus: Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Levis: Astellas and FujiFilm: Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Honoraria; Amgen, Astellas Pharma, Daiichi-Sankyo, FujiFilm, and Menarini: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria; Takeda: Honoraria. Montesinos: Stemline/Menarini: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics: Consultancy; Glycomimetics: Consultancy; Tolero Pharmaceutical: Consultancy; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau. Röllig: Roche: Honoraria, Research Funding; Bristol-Meyer-Squibb: Honoraria, Research Funding; Janssen: Honoraria; Jazz: Honoraria; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Honoraria; AbbVie: Honoraria, Research Funding. Schlenk: Novartis: Honoraria; Pfizer: Honoraria, Research Funding, Speakers Bureau; Hexal: Honoraria; Neovio Biotech: Honoraria; Daiichi Sankyo: Honoraria, Research Funding; Celgene: Honoraria; Astellas: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria; Agios: Honoraria; Roche: Honoraria, Research Funding; AstraZeneca: Research Funding; Boehringer Ingelheim: Research Funding.

Abstract: Invasive aspergillosis ( IA ) is a severe complication in immunocompromised patients. Early diagnosis is crucial to decrease its high mortality, yet the diagnostic gold standard (histopathology and culture) is time‐consuming and cannot offer early confirmation of IA . Detection of IA by polymerase chain reaction ( PCR ) shows promising potential. Various studies have analysed its diagnostic performance in different clinical settings, especially addressing optimal specimen selection. However, direct comparison of different types of specimens in individual patients though essential, is rarely reported. We systematically assessed the diagnostic performance of an Aspergillus ‐specific nested PCR by investigating specimens from the site of infection and comparing it with concurrent blood samples in individual patients (pts) with IA . In a retrospective multicenter analysis PCR was performed on clinical specimens (n = 138) of immunocompromised high‐risk pts (n = 133) from the site of infection together with concurrent blood samples. 38 pts were classified as proven/probable, 67 as possible and 28 as no IA according to 2008 European Organization for Research and Treatment of Cancer/Mycoses Study Group consensus definitions. A considerably superior performance of PCR from the site of infection was observed particularly in pts during antifungal prophylaxis ( AFP )/antifungal therapy ( AFT ). Besides a specificity of 85%, sensitivity varied markedly in BAL (64%), CSF (100%), tissue samples (67%) as opposed to concurrent blood samples (8%). Our results further emphasise the need for investigating clinical samples from the site of infection in case of suspected IA to further establish or rule out the diagnosis.

Abstract: Background Venetoclax (VEN)-based combination therapy with hypomethylating agents (HMA) has been approved for first-line treatment in patients ineligible for intensive treatment based on two randomized trials. There is some evidence for efficacy also in the in relapsed/ refractory setting (R/R), but comparative controlled data is lacking. Here, we report our experience of VEN-Azacitidine (AZA) in R/R AML salvage treatment and bridge to allogeneic cell transplantation (allo-HCT) in fit patients compared to historical data from the Study Alliance Leukemia (SAL) registry (ClinicalTrials.gov Identifier: NCT03188874). Design/Methods We analyzed all patients with R/R AML after initial intensive therapy, who started VEN-AZA salvage treatment at the University Hospital Heidelberg, between October 2018 and October 2020. Patients, who were bridged to allo-HCT were compared in a multivariable analysis to data of R/R AML patients from the SAL registry receiving an allo-HCT. Results: A total of 26 patients (median age 60 years, range 23 to 79) were included. All patients initially received intensive therapy, 16 patients (62%) had been refractory to intensive induction therapy with DA (daunorubicin, cytarabine) (11 patients)/ CPX-351 (2 patients) or to an intensive salvage therapy regime with HAM (2 patients)/ Cytarabin-Bortezomib (1 patient). Ten patients (38%) had morphologic (7 patients) or molecular relapse (3 patients) after intensive first line therapy. The distribution of AML according to WHO-2016 classification was n=10 recurrent genetic abnormalities (n= 7, mutated NPM1; n=1, biallelic CEBPA mutations; n=1, mutated RUNX1; n=1, CBFB-MYH11), n=10 AML with MRC, n=6 AML NOS. According to the 2017 ELN classification, 9 patients (34,5%) had low risk, 8 (31%) intermediate risk and 9 (34,5%) adverse risk disease. All patients received AZA 75mg/m² for 7 days combined with VEN 400mg/day after initial ramp up or a reduced dose of 100mg/day in case of co-medication with azoles in 28 days cycles. Best response was CR/CRi in 58% (n=15), PR in 23% (n=6) patients. Day 30-mortality was 0%, day 60-mortality was 4% (n=1). Allo-HCT was performed in 20 patients (77%). Pre-Allo-HCT remission status was CR/CRi in 11 (55%), PR in 4 (20%) patients and MLFS in 1 patient and 4 patients had active disease (n=3, relapse after achieving CR/CRi on VEN-AZA, n=1 refractory to VEN-AZA.). At the time of analysis 15 (75%) of the 20 bridged patients were alive and 11 (55%) are still in CR resulting in a median relapse-free survival in bridged patients of 406 days, whereas all patients not proceeding to allo-HCT died after a median of 139 days. In total, 63 patients with R/R AML were identified in the SAL-registry proceeding to allo-HCT with non VEN-based salvage attempt. Pre-Allo-HCT remission status was CR/CRi in 18 (28%), PR in 15 (24%), unknown in 13 patients (21%) and 17 (27%) patients had active disease (n=9 relapsed, n=8 refractory). Patients of the SAL registry were younger (median, 55 years; range, 22-75 years) and more patients were ELN-int (low risk, 32%, n=20; int, 52%, n=33, adv, 16%, n=10). Median follow-up in the VEN-AZA and the SAL cohorts were 1.4 years and 4.6 years, respectively. Cox-regression modeling of survival measured from the date of being refractory/relapsed revealed a non-significant effect of the cohorts favoring the VEN-AZA salvage therapy (HR, 0.87, p=0.73). However, stratified univariable survival analysis revealed in trend better survival (p=0.10) in the VEN-AZA compared to the SAL cohort with 77% (95%-CI, 62-95%) and 74% (95%-CI, 57-97%) as well as 84% (95%-CI, 76-94%) and 52% (95-CI, 41-68%) 1- and 2-years survival, respectively. Conclusion: Our data confirms the efficacy of VEN-AZA in patients with R/R AML and underlines its potential as an effective strategy for bridging to successful allo-HCT. Disclosures Unglaub: JazzPharma: Consultancy, Other: travel costs/ conference fee; Novartis: Consultancy, Other: travel costs/ conference fee. Schlenk: Boehringer Ingelheim: Research Funding; AstraZeneca: Research Funding; Roche: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria; Neovio Biotech: Honoraria; Hexal: Honoraria; Daiichi Sankyo: Honoraria, Research Funding; Celgene: Honoraria; Astellas: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria; Agios: Honoraria. Middeke: Janssen: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Gilead: Consultancy; Abbvie: Consultancy, Honoraria; Jazz: Consultancy; Pfizer: Consultancy, Honoraria; Sanofi: Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Novartis: Consultancy; Glycostem: Consultancy; UCB: Honoraria. Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Haenel: GSK: Consultancy; Jazz: Consultancy, Honoraria; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Crysandt: Pfizer: Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria. Fransecky: Medac: Honoraria; Abbvie: Honoraria, Research Funding; Amgen: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. Seggewiss-Bernhardt: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; ipsen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; EusaPharma: Honoraria, Membership on an entity's Board of Directors or advisory committees. Platzbecker: AbbVie: Honoraria; Celgene/BMS: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Geron: Honoraria; Takeda: Honoraria. Baldus: Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria; Novartis: Honoraria. Dreger: Bluebird Bio: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; BMS: Consultancy; AbbVie: Consultancy, Speakers Bureau; Janssen: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Speakers Bureau. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Sauer: Takeda: Consultancy, Other: DSMB/SAB Member; Matterhorn Biosciences AG: Consultancy, Other: DSMB/SAB Member; Abbvie: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau. OffLabel Disclosure: off-label use of Venetoclax-based combination therapy in relapsed or refractory AML

Abstract: Background In newly diagnosed acute myeloid leukemia (AML), the general recommendation is to start treatment immediately after the diagnosis has been made. This paradigm is based both on the observation that untreated acute leukemia has a poor prognosis and on retrospective analyses demonstrating a shorter survival in younger AML patients (pts) in whom treatment was delayed by more than 5 days (Sekeres et al., 2009). A more recent single-center analysis came to a different conclusion, showing no prognostic effect for the time from diagnosis to treatment (TDT; Bertoli et al., 2013). We explored the relationship between TDT and prognosis on a large set of real-world data from the AML registry of the Study Alliance Leukemia (SAL) and compared it to the published cohorts. Methods The SAL runs a transregional AML registry in 46 treatment centers across Germany (NCT03188874). All registered patients with an intensive induction treatment, a minimum follow-up time of 12 months and no acute promyelocytic leukemia were selected (n=2,200). Treatment start was defined by the first day of cytarabine, whereas single agent hydroxyurea (HU) was labeled as pretreatment. We analyzed the influence of TDT on complete remission (CR), early death (ED) and overall survival (OS) in univariable analyses for each day of treatment delay, in groups of 0-5, 6-10, 11-15 and & gt;15 days of TDT, and by using the restricted cubic spline (RCS) method for data modelling. In order to adjust for the influence of established prognostic variables on the outcomes, we used multivariable regression models and propensity score weighting. The influence of HU pretreatment on outcomes was investigated by introducing an interaction term between TDT and the presence of HU pretreatment. Results The median age was 59 years (y) (IQR 50-68), the proportion of pts with favorable, intermediate and adverse genetic risk according to ELN was 27%, 53%, and 20%; & gt;95% of pts received induction treatment with standard 7+3. HU pretreatment was administered in 4% of pts. The median TDT was 3 days (IQR 2-6). Descriptive statistics after grouping of pts showed the highest median age and the lowest proportion of NPM1 mutated and favorable risk in the TDT group 11-15. Of all pts, 79% achieved a CR/CRi; unadjusted CR rates for the patient groups with TDT of 0-5, 6-10, 11-15 and & gt;15 days were 80%, 77%, 74% and 76%, respectively (p=0.317). In multivariable analysis accounting for the influence of ELN risk, age, WBC, LDH, de novo versus secondary AML and ECOG, the OR for each additional day of TDT was 0.99 (95%-CI, 0.97-1.00; p=0.124). Four percent of pts died within the first 30 days from treatment start. The respective rates in the four TDT categories were 4.0%, 3.8%, 5.1% and 4.1% (p=0.960). In multivariable analysis, the OR for TDT was 1.01 (95%-CI, 0.98-1.05; p=0.549). After a median follow-up of 40 months, the 2-y OS of all pts was 51%. The unadjusted 2-y OS rates stratified by TDT of 0-5, 6-10, 11-15, & gt;15 days were 52, 49, 46, and 51% (see Table 1 and Figure 1). The hazard ratio (HR) for each day of treatment delay was 1.00 (95%-CI; 0.99-1.01; p=0.317). In multivariable Cox regression analysis, the HR for TDT as continuous variable was 1.00 (95%-CI, 0.99-1.01; p=0.689). When OS was analyzed separately stratified for age ≤60 and & gt;60 ys and for high versus lower initial WBC defined by a threshold of 50 x 109/L, no significant differences between TDT groups were observed. Multivariable models using TDT as a grouped variable or with RCS did not provide evidence for a significant influence of TDT on outcomes. Propensity score matching of pts in the four TDT groups did not reveal an influence on outcomes. The use of HU was not associated with CR, ED nor OS. Conclusion Our study on 2,200 newly diagnosed registry pts receiving consistent intensive induction with standard-dose cytarabine plus daunorubicin (7+3) suggests that TDT is not related to response or survival, neither in younger nor in older pts. Despite multivariable analyses, a bias towards longer TDT intervals in pts judged to be clinically stable by the treating physician cannot be excluded entirely. As treatment stratification in intensive first-line treatment of AML evolves, the TDT data suggests that it may be a safe and reasonable approach to wait for genetic and other laboratory test results in order to assign clinically stable pts to the best available treatment option before the start of intensive treatment. Disclosures Krämer: Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding; BMS: Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Hänel:Roche: Honoraria; Amgen: Honoraria; Celgene: Other: advisory board; Novartis: Honoraria; Takeda: Other: advisory board. Jost:Daiichi: Honoraria; Sanofi: Honoraria; Gilead: Other: travel grants; Jazz Pharmaceuticals: Honoraria. Brümmendorf:Merck: Consultancy; Janssen: Consultancy; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; University Hospital of the RWTH Aachen: Employment; Ariad: Consultancy. Krause:Siemens: Research Funding; Takeda: Honoraria; MSD: Honoraria; Gilead: Other: travel; Celgene Corporation: Other: Travel. Scholl:Novartis: Other: Project funding; Pfizer: Other: Advisory boards; Gilead: Other: Project funding; Daiichi Sankyo: Other: Advisory boards; AbbVie: Other: Advisory boards. Hochhaus:Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; Incyte: Research Funding; MSD: Research Funding. Kiani:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Middeke:Sanofi: Research Funding, Speakers Bureau; Roche: Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Gilead: Consultancy; Janssen: Consultancy, Speakers Bureau; MSD: Consultancy. Thiede:AgenDix GmbH: Employment, Equity Ownership; Novartis: Research Funding, Speakers Bureau; Bayer: Research Funding; Daiichi-Sankyo: Speakers Bureau. Stoelzel:JAZZ Pharmaceuticals: Consultancy; Neovii: Other: Travel funding; Shire: Consultancy, Other: Travel funding. Platzbecker:Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding.

Abstract: We retrospectively studied 125 patients with acute myeloid leukemia and trisomy 4 (median age at diagnosis, 58 years; range, 16-77 years) treated between 2000 and 2019 within a multicenter study. Trisomy 4 was the sole abnormality in 28 (22%) patients and additional abnormalities were present in 97 (78%) patients. Twenty-two (22%) and 15 (15%) of 101 tested patients harbored NPM1 and FLT3-ITD mutations. Two (3%) of 72 tested patients had double CEBPA mutations. Data on response to intensive anthracycline-based induction therapy were available for 119 patients. Complete remission was achieved in 67% (n=80) and the early death rate was 5% (n=6). Notably, patients with trisomy 4 as sole abnormality had a complete remission rate of 89%. Allogeneic hematopoietic cell transplantation was performed in 40 (34%) patients, of whom 19 were transplanted in first complete remission. The median follow-up of the intensively treated cohort was 5.76 years (95% confidence interval [95% CI]: 2.99-7.61 years). The 5-year overall survival and relapse-free survival rates were 30% (95% CI: 22-41%) and 27% (95% CI: 18-41%), respectively. An Andersen-Gill regression model on overall survival revealed that favorable-risk according to the European LeukemiaNet classification (hazard ratio [HR] =0.34; P=0.006) and trisomy 4 as sole abnormality (HR=0.41; P=0.01) were favorable factors, whereas age with a difference of 10 years (HR=1.15; P=0.11), female gender (HR=0.74; P=0.20) and allogeneic hematopoietic cell transplantation (HR=0.64; P=0.14) did not have an significant impact. In our cohort, patients with trisomy 4 as their sole abnormality had a high complete remission rate and favorable clinical outcome. Allogeneic hematopoietic cell transplantation did not seem to improve overall survival.