Abstract: Abstract 412 Background: A large proportion of patients are currently not eligible for genotype-adapted strategies in acute myeloid leukemia (AML), in particular those lacking specific genetic aberrations such as PML-RARA, CBFB-MYH11, RUNX1-RUNX1T1, NPM1 or activating FLT3 mutations. This subgroup of patients accounts for about one-third of all AML patients and mainly includes the large group of AML with myelodysplasia-related changes, AML with recurrent cytogenetic abnormalities [inv(3) or t(3;3), t(9;11), t(v;11q23)] and cytogenetically normal AML (CN-AML) with wild-type NPM1 and FLT3. Prognosis in this subgroup of patients is generally poor. Azacitidine has been shown to be active in AML with low blast counts frequently observed in AML with myelodysplasia-related changes and in CN-AML in the absence of specific gene mutations. Aims: To evaluate clinical efficacy of azacitidine in combination with intensive induction chemotherapy and in maintenance for two years as single agent in patients with AML who are not candidates for genotype-adapted treatment approaches. Methods: Patients with AML in the absence of specific genetic aberrations (PML-RARA, CBFB-MYH11, RUNX1-RUNX1T1, NPM1 mutation, activating FLT3 mutations) who are fit for intensive chemotherapy were eligible. Patients were up-front randomized for induction therapy into one standard arm and three experimental arms; i) ICE (standard arm), idarubicin (12 mg/m2/day, iv, days 1,3,5), cytarabine (100 mg/m2/day, cont. infusion, days 1–7), etoposide (100 mg/m2/day, iv, days 1,2,3); ii) AZA-prior, azacitidine (100 mg/m2/day, sc, days 1–5), idarubicin (12 mg/m2/day, iv, days 6, 8, 10), etoposide 100 mg/m2/day, iv, days 6,7,8); iii) AZA-concurrent, azacitidine (100 mg/m2/day, sc, days 1–5), idarubicin (12 mg/m2/day, iv, days 1,3,5), etoposide 100 mg/m2/day, iv, days 1,2,3); iv) AZA-after, idarubicin (12 mg/m2/day, iv, days 1,3,5), etoposide 100 mg/m2/day, iv, days 1,2,3), azacitidine (100 mg/m2/day, sc, days 4–8). After two induction cycles for patients achieving complete remission (CR), consolidation therapy was prioritized; first priority) allogeneic hematopoietic blood stem cell transplantation (HSCT) from matched related as well as unrelated donors, second priority) 3 courses of high-dose cytarabine followed by two-year maintenance therapy with azacitidine as single agent (50 mg/m2/day, sc, days 1–5, every 4 weeks) in patients initially randomized to experimental treatment. The primary endpoint was achievement of CR. The statistical design of the study was based on the Simon's optimal two-stage design applied for each arm separately. The null hypothesis was CR-rate equal or below 0.40 whereas the alternative hypothesis was a CR rate of at least 0.55 with a power of 80% and a level of significance of 5%. Thus, in each arm at least 12 of 26 patients with response to induction therapy were necessary after the first to proceed to the second stage. Results: During the first stage of the study 104 patients were randomized; median age was 62.5 years (range 18–82), 46% were female. Data on cytogenetics showed intermediate risk karyotype in 67% (n=50) including CN-AML (n=31) and high-risk karyotype in 33% (n=25). The most frequent serious adverse events were grade 3/4 infection with an overall incidence of 25% and ranging from 20 to 34% in the different treatment arms. The number of responding patients in the treatment arms AZA-prior and AZA-concurrent after the first stage of the study were 11 of 26 (42%) and 10 of 26 (38%)Both arms, AZA-prior and were terminated accordingly. In contrast, the treatment arms ICE and AZA-after were carried forward to the second stage of patient recruitment since responding patients at that time were 14 of 26 (54%) in both arms. In total, 100 patients each have been enrolled in both treatment arms, ICE and AZA-after, with CR-rates of 59% and 52%, respectively (p=0.39). To date, 60 patients received an allogeneic HSCT (n=36 matched unrelated donors, n=23 matched related donors, n=1 haploidentical family donor). Maintenance treatment was started in 12 patients. Conclusion: Induction therapy with ICE or idarubicin, etoposide followed by azacitidine (AZA-after) appears equally effective in producing CR in patients with AML who are not candidates for genotype-adapted treatment approaches. An amendment perpetuating the treatment arms ICE and AZA-after within a phase-III concept is planned. Disclosures: Schlenk: Celgene: Research Funding. Off Label Use: Azacitidine combined with intensive chemotherapy.

Abstract: Background: Internal tandem duplications (ITD) in the receptor tyrosine kinase FLT3 occur in roughly 25% of younger adult patients (pts) with acute myeloid leukemia (AML). The multi-targeted kinase inhibitor midostaurin combined with intensive chemotherapy has shown activity against AML with FLT3 mutations. However, toxicity and potential drug-drug interactions with strong CYP3A4 inhibitors such as posaconazole may necessitate dose reduction. Aims: To evaluate the impact of age and midostaurin dose-adaptation after intensive induction chemotherapy on response and outcome in AML with FLT3-ITD within the AMLSG 16-10 trial (NCT01477606). Methods: The study included adult pts (age 18-70 years (yrs)) with newly diagnosed FLT3-ITD positive AML enrolled in the ongoing single-arm phase-II AMLSG 16-10 trial. Pts with acute promyelocytic leukemia were not eligible. The presence of FLT3-ITD was analyzed within our diagnostic study AMLSG-BiO (NCT01252485) by Genescan-based DNA fragment-length analysis. Induction therapy consisted of daunorubicin (60 mg/m², d1-3) and cytarabine (200 mg/m², continuously, d1-7); midostaurin 50 mg bid was applied from day 8 until 48h before start of the next treatment cycle. A second cycle was allowed in case of partial remission (PR). For consolidation therapy, pts proceeded to allogeneic hematopoietic-cell transplantation (HCT) as first priority; if alloHCT was not feasible, pts received three cycles of age-adapted high-dose cytarabine (HDAC) in combination with midostaurin starting on day 6. In all pts one-year maintenance therapy with midostaurin was intended. The first patient entered the study in June 2012 and in April 2014, after recruitment of n=147 pts, the study was amended including a sample size increase to 284 pts and a dose reduction to 12.5% of the initial dose of midostaurin in case of co-medication with strong CYP3A4 inhibitors (e.g. posaconazole). This report focuses on age and the comparison between the first (n=147) and the second cohort (n=137) of the study in terms midostaurin dose-adaptation. Results: Patient characteristics were as follows: median age 54 yrs (range, 18-70; younger, 68% 〈 60 yrs; older, 32% ≥ 60 yrs); median white cell count 44.7G/l (range 1.1-1543 G/l); karyotype, n=161 normal, n=16 high-risk according to ELN recommendations; mutated NPM1 n=174 (59%). Data on response to first induction therapy were available in 277 pts; complete remission (CR) including CR with incomplete hematological recovery (CRi) 60%, PR 20%, refractory disease (RD) 15%, and death 5%. A second induction cycle was given in 54 pts. Overall response (CR/CRi) after induction therapy was 76% (76%, younger; 76%, older) and death 6% (4%, younger; 10% older). The dose of midostaurin during first induction therapy was reduced in 53% and 71% of patients in cohort-1 and cohort-2, respectively. Reasons for dose reduction were in 58% and 49% toxicity, and in 9% and 23% co-medication in cohort-1 and cohort-2, respectively. No difference in response to induction therapy was noted between cohorts (p=0.81). Median follow-up was 18 months. Overall 146 pts received an alloHCT, 128 in first CR (n=94 younger, n=34 older; n=92 from a matched unrelated and n=36 from a matched related donor). In pts receiving an alloHCT within the protocol in median two chemotherapy cycles were applied before transplant (range 1-4). The cumulative incidence of relapse (CIR) and death after transplant were 13% (SE 3.2%) and 16% (SE 3.5%) without differences (p=0.97, p=0.41, respectively) between younger and older patients. So far maintenance therapy was started in 86 pts, 61 pts after alloHCT and 25 pts after HDAC. Fifty-five adverse events 3°/4° were reported being attributed to midostaurin; cytopenias after alloHCT were the most frequent (29%). CIR in patients starting maintenance therapy was 20% one year after start of maintenance without difference between alloHCT and HiDAC (p=0.99). In addition, no difference in CIR was identified in patients after consolidation with alloHCT or HDAC according to dose reduction of midostaurin during first induction therapy (p=0.43, p=0.98, respectively). Median overall survival was 25 months (younger, 26 months; older 23 months; p=0.15). Conclusions: The addition of midostaurin to intensive induction therapy and as maintenance after alloHCT or HDAC is feasible and effective without an impact of age and dose adaptation on outcome. Disclosures Schlenk: Amgen: Research Funding; Pfizer: Honoraria, Research Funding. Fiedler:GSO: Other: Travel; Pfizer: Research Funding; Kolltan: Research Funding; Amgen: Consultancy, Other: Travel, Patents & Royalties, Research Funding; Gilead: Other: Travel; Ariad/Incyte: Consultancy; Novartis: Consultancy; Teva: Other: Travel. Lübbert:Celgene: Other: Travel Funding; Janssen-Cilag: Other: Travel Funding, Research Funding; Ratiopharm: Other: Study drug valproic acid. Greil:Janssen-Cilag: Honoraria; Genentech: Honoraria, Research Funding; Mundipharma: Honoraria, Research Funding; Merck: Honoraria; AstraZeneca: Honoraria; Boehringer-Ingelheim: Honoraria; GSK: Research Funding; Ratiopharm: Research Funding; Cephalon: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; Bristol-Myers-Squibb: Consultancy, Honoraria; Pfizer: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Sanofi Aventis: Honoraria; Eisai: Honoraria; Amgen: Honoraria, Research Funding. Greiner:BMS: Research Funding. Paschka:ASTEX Pharmaceuticals: Consultancy; Novartis: Consultancy; Medupdate GmbH: Honoraria; Bristol-Myers Squibb: Honoraria; Pfizer Pharma GmbH: Honoraria; Celgene: Honoraria. Heuser:Bayer Pharma AG: Research Funding; Karyopharm Therapeutics Inc: Research Funding; Novartis: Consultancy, Research Funding; Celgene: Honoraria; Pfizer: Research Funding; BerGenBio: Research Funding; Tetralogic: Research Funding.

Abstract: High CD33 expression in acute myeloid leukemia (AML) with mutated NPM1 provides a rationale for the evaluation of gemtuzumab ozogamicin (GO) in this AML entity. We conducted a randomized trial to evaluate GO in combination with intensive induction and consolidation therapy in NPM1-mutated AML. PATIENTS AND METHODS Between May 2010 and September 2017, patients ≥ 18 years old and considered eligible for intensive therapy were randomly assigned up front for induction therapy with idarubicin, cytarabine, etoposide, and all- trans-retinoic acid with or without GO. The early ( P = .02) primary end point of event-free survival (EFS) was evaluated 6 months after completion of patient recruitment. RESULTS Five hundred eighty-eight patients were randomly assigned (standard arm, n = 296; GO arm, n = 292). EFS in the GO arm was not significantly different compared with that in the standard arm (hazard ratio, 0.83; 95% CI, 0.65 to 1.04; P = .10). The early death rate during induction therapy was 10.3% in the GO arm and 5.7% in the standard arm ( P = .05). Causes of death in both arms were mainly infections. The cumulative incidence of relapse (CIR) in patients achieving a complete remission (CR) or CR with incomplete hematologic recovery (CRi) was significantly reduced in the GO arm compared with the standard arm ( P = .005), with no difference in the cumulative incidence of death ( P = .80). Subgroup analysis revealed a significant beneficial effect of GO in female, younger (≤ 70 years), and FLT3 internal tandem duplication–negative patients with respect to EFS and CIR. CONCLUSION The trial did not meet its early primary end point of EFS, mainly as a result of a higher early death rate in the GO arm. However, in patients achieving CR/CRi after induction therapy, significantly fewer relapses occurred in the GO compared with the standard arm.

Abstract: To assess the impact of allogeneic hematopoietic stem-cell transplantation (HSCT) from matched related donors (MRDs) and matched unrelated donors (MUDs) on outcome in high-risk patients with acute myeloid leukemia (AML) within a prospective multicenter treatment trial. Patients and Methods Between 1998 and 2004, 844 patients (median age, 48 years; range, 16 to 62 years) with AML were enrolled onto protocol AMLHD98A that included a risk-adapted treatment strategy. High risk was defined by the presence of unfavorable cytogenetics and/or by no response to induction therapy. Results Two hundred sixty-seven (32%) of 844 patients were assigned to the high-risk group. Of these 267 patients, 51 patients (19%) achieved complete remission but had adverse cytogenetics, and 216 patients (81%) had no response to induction therapy. Allogeneic HSCT was actually performed in 162 (61%) of 267 high-risk patients, after a median time of 147 days after diagnosis. Graft sources were as follows: MRD (n = 62), MUD (n = 89), haploidentical donor (n = 10), and cord blood (n = 1). The 5-year overall survival rates were 6.5% (95% CI, 3.1% to 13.6%) for patients (n = 105) not proceeding to HSCT and 25.1% (95% CI, 19.1% to 33.0%; from date of transplantation) for patients (n = 162) receiving HSCT. Multivariable analysis including allogeneic HSCT as a time-dependent covariable revealed that allogeneic HSCT significantly improved outcome; there was no difference in outcome between allogeneic HSCT from MRD and MUD. Conclusion Allogeneic HSCT in younger adults with high-risk AML has a significant beneficial impact on outcome, and allogeneic HSCT from MRD and MUD yields similar results.

Abstract: Background: Mutations of the NPM1 gene are one of the most frequent genetic aberrations in adult AML. AML with mutated NPM1 is categorized as a disease entity according the WHO-2016 classification and clinically associated with female sex, high white blood cells at diagnosis, normal karyotype and high CD33 antigen expression. We recently showed that patients with NPM1-mutated AML benefit from all-trans retinoic acid (ATRA) as adjunct to intensive induction therapy (Ann Hematol. 2016; 95:1931-1942; Haematologica. 2009;94:54-60). Based on the regular high CD33 expression in AML with mutated NPM1 we hypothesized that gemtuzumab ozogamicin (GO) added to intensive therapy with ATRA may further improve clinical outcome in AML with mutated NPM1. Aim: To evaluate GO in combination with intensive induction and consolidation therapy and ATRA in NPM1 mutated AML within the randomized AMLSG 09-09 trial (NCT00893399) Methods: Between May 2010 and September 2017, patients ≥18 years of age and considered eligible for intensive therapy were randomized up-front for open-label treatment with GO. Induction therapy consisted of two cycles of A-ICE (idarubicin 12mg/m² iv, day 1,3,5 [in induction II and for patients 〉 60 years reduced to d 1, 3]; cytarabine 100mg/m² continuous iv, day 1 to 7; etoposide 100mg/m² iv, day 1-3 [in induction II and for patients 〉 60 years reduced to d 1, 3]; ATRA 45 mg/m²/day po on days 6-8 and 15mg/m² days 9-21, +/- GO 3mg/m² iv day 1). Consolidation therapy consisted of 3 cycles of high-dose cytarabine (HiDAC; 3g/m² [reduced to 1g/m² in patients 〉 60 years] bid, days 1-3; Pegfilgrastim 6mg sc, day 10; ATRA 15 mg/m²/day po, days 4-21; +/- GO 3mg/m² on day 1 [first consolidation only] ). The primary endpoints of the study were event-free survival (EFS) as early endpoint tested 6 months and overall survival (OS) tested 4 years after study completion with sequential testing according the fallback procedure described by Wiens (Statistics 2003;2:211-215). This report focusses on the early EFS endpoint. Further secondary endpoints were response to induction therapy, cumulative incidence of relapse (CIR) and cumulative incidence of death (CID). Results: In total 588 patients were evaluable for analysis (n=296, standard-arm; n=292 GO-arm). Median age was 58.7 years (range, 18.4-82.3 years), ECOG performance status was 0 in 34.1% and 1 in 55.1%, and FLT3-ITD was present in 16.8% of the patients, with baseline characteristics well balanced between the two arms. After first induction therapy death rates were significantly higher in the GO-arm (7.5%) (p=0.02) compared to the standard-arm (3.4%); in both study-arms causes of death were mainly infections. Following induction therapy complete remission (CR) and CR with incomplete count recovery (CRi) were 88.5% and 85.3% (p=0.28), refractory disease (RD) 6.1% and 5.1% (p=0.72), death 5.4% and 9.6% (p=0.06) in the standard- and GO-arm, respectively. Due to prolonged thrombocytopenia after second induction therapy in the GO-arm, the protocol was amended in that GO was omitted in second induction and first consolidation cycles, if prolonged cytopenias were observed during first induction therapy. The study treatment was completed in 197 and 171 patients (p=0.11), allogeneic hematopoietic cell transplantation in first CR was performed in 18 and 21 patients (p=0.51) in the standard- and GO-arm, respectively. Median follow-up was 2.6 years (95%-CI, 2.4-3.1 years). Two- and 4-year EFS were 53% (95%-CI, 48-60%) and 58% (95%-CI, 52%-64%), and 44% (95%-CI, 38-52%) and 52% (95%-CI, 46%-59%) in the standard- and GO-arm, respectively. According to the pre-specified significance level of 0.025, EFS in the GO-arm was not different to that in the standard-arm (p=0.21). In patients achieving CR/CRi after induction therapy, CIR was significantly reduced in the GO-arm compared to the standard-arm (p=0.018), whereas no difference in CID was noted between both arms (p=0.89). Conclusion: The addition of GO to intensive induction therapy with ICE plus ATRA was associated with a higher death rate. In patients achieving a CR/CRi after induction therapy significantly less relapses occurred in the GO- compared to the standard-arm. Disclosures Schlenk: Pfizer: Research Funding, Speakers Bureau. Paschka:Astex: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees, Travel support; Otsuka: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Bristol-Meyers Squibb: Other: Travel support, Speakers Bureau; Jazz: Speakers Bureau; Amgen: Other: Travel support; Janssen: Other: Travel support; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Travel support. Fiedler:Amgen: Other: support for meetíng attendance; Gilead: Other: support for meeting attendance; Pfizer: Research Funding; Amgen: Research Funding; Amgen: Patents & Royalties; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; ARIAD/Incyte: Membership on an entity's Board of Directors or advisory committees, support for meeting attendance; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSO: Other: support for meeting attendance; Teva: Other: support for meeting attendance; JAZZ Pharmaceuticals: Other: support for meeting attendance; Daiichi Sankyo: Other: support for meeting attendance. Lübbert:Cheplapharm: Other: Study drug; Celgene: Other: Travel Support; Janssen: Honoraria, Research Funding; TEVA: Other: Study drug. Götze:Novartis: Honoraria; Takeda: Honoraria, Other: Travel aid ASH 2017; JAZZ Pharmaceuticals: Honoraria; Celgene: Honoraria, Research Funding. Schleicher:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Investigator; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Ipsen: Membership on an entity's Board of Directors or advisory committees; Eissai: Other: Investigator; Astra Zeneca: Other: Investigator; Pfizer: Speakers Bureau; Janssen: Speakers Bureau; Celgene: Speakers Bureau. Greil:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MSD: Honoraria, Research Funding; Janssen: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Honoraria, Research Funding; Astra Zeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sandoz: Honoraria, Research Funding; Amgen: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Heuser:Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Astellas: Research Funding; BergenBio: Research Funding; Karyopharm: Research Funding; Daiichi Sankyo: Research Funding; Sunesis: Research Funding; Tetralogic: Research Funding; Bayer Pharma AG: Consultancy, Research Funding; StemLine Therapeutics: Consultancy; Janssen: Consultancy. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Döhner:Agios: Consultancy, Honoraria; Pfizer: Research Funding; Sunesis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Agios: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Celator: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Jazz: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding; Sunesis: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Research Funding; Seattle Genetics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Celator: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding.

Abstract: Core-binding factor (CBF) acute myeloid leukemia (AML) encompasses AML with inv(16)(p13.1q22) and AML with t(8;21)(q22;q22.1). Despite sharing a common pathogenic mechanism involving rearrangements of the CBF transcriptional complex, there is growing evidence for considerable genotypic heterogeneity. We comprehensively characterized the mutational landscape of 350 adult CBF-AML [inv(16): n = 160, t(8;21): n = 190] performing targeted sequencing of 230 myeloid cancer-associated genes. Apart from common mutations in signaling genes, mainly NRAS, KIT, and FLT3, both CBF-AML entities demonstrated a remarkably diverse pattern with respect to the underlying cooperating molecular events, in particular in genes encoding for epigenetic modifiers and the cohesin complex. In addition, recurrent mutations in novel collaborating candidate genes such as SRCAP (5% overall) and DNM2 (6% of t(8;21) AML) were identified. Moreover, aberrations altering transcription and differentiation occurred at earlier leukemic stages and preceded mutations impairing proliferation. Lasso-penalized models revealed an inferior prognosis for t(8;21) AML, trisomy 8, as well as FLT3 and KIT exon 17 mutations, whereas NRAS and WT1 mutations conferred superior prognosis. Interestingly, clonal heterogeneity was associated with a favorable prognosis. When entering mutations by functional groups in the model, mutations in genes of the methylation group (ie, DNMT3A, TET2) had a strong negative prognostic impact.

Abstract: Monitoring of measurable residual disease (MRD) provides prognostic information in patients with Nucleophosmin1-mutated (NPM1mut) acute myeloid leukemia (AML) and represents a powerful tool to evaluate treatment effects within clinical trials. We determined NPM1mut transcript levels (TLs) by quantitative reverse-transcription polymerase chain reaction and evaluated the prognostic impact of NPM1mut MRD and the effect of gemtuzumab ozogamicin (GO) on NPM1mut TLs and the cumulative incidence of relapse (CIR) in patients with NPM1mut AML enrolled in the randomized phase 3 AMLSG 09-09 trial. A total of 3733 bone marrow (BM) samples and 3793 peripheral blood (PB) samples from 469 patients were analyzed. NPM1mut TL log10 reduction ≥ 3 and achievement of MRD negativity in BM and PB were significantly associated with a lower CIR rate, after 2 treatment cycles and at end of treatment (EOT). In multivariate analyses, MRD positivity was consistently revealed to be a poor prognostic factor in BM and PB. With regard to treatment effect, the median NPM1mut TLs were significantly lower in the GO-Arm across all treatment cycles, resulting in a significantly greater proportion of patients achieving MRD negativity at EOT (56% vs 41%; P = .01). The better reduction in NPM1mut TLs after 2 treatment cycles in MRD positive patients by the addition of GO led to a significantly lower CIR rate (4-year CIR, 29.3% vs 45.7%, P = .009). In conclusion, the addition of GO to intensive chemotherapy in NPM1mut AML resulted in a significantly better reduction in NPM1mut TLs across all treatment cycles, leading to a significantly lower relapse rate.

Abstract: Background: In a previous randomized trial (AML HD98B) of the AMLSG in elderly ( 〉 60 yrs) patients with AML (excluding APL), we could demonstrate that all-trans retinoic acid (ATRA) given as adjunct to intensive chemotherapy significantly improved complete remission (CR) rate and overall survival (OS). Our hypothesis for this study was that this beneficial effect of ATRA may be confined to a specific genotypic subset of AML. Aims: To evaluate the impact of ATRA on clinical outcome in cytogenetic and molecular genetic subsets of AML. Methods: Between 1998 and 2004, a total of 372 patients were enrolled. 242 patients were randomized for ATRA as adjunct to intensive induction (idarubicin, cytarabine, etoposide) and first consolidation therapy (intermediate-dose cytarabine) (Schlenk et al., Leukemia 2004), followed by a second randomization between further intensive consolidation versus a one-year oral maintenance therapy (Schlenk et al., Leukemia 2006). After an interim analysis in 2003, first randomization was stopped; the following 130 patients received chemotherapy without ATRA. Data from conventional cytogenetics and from fluorescence in-situ hybridization were previously reported (Fröhling et al., Blood 2006). All available leukemia specimens were analyzed for mutations in the genes encoding NPM1, CEBPA, and FLT3. Results: Median age of the 372 patients was 67 years (range: 61 to 83 yrs); median follow-up time was 68 months. 67% of the patients had de novo AML, 33% had secondary AML. Incidences of mutations were as follows (no. of specimens analyzed): NPM1 mutation, 25% (n=242); FLT3 internal tandem duplication (ITD), 18% (n=263); FLT3 tyrosine kinase domain mutation, 5% (n=244); CEBPA mutation, 8% (CEBPA analyzed only in normal karyotype samples; n=109). Logistic regression analysis performed on all patients identified three significant variables for achievement of CR: the genotype NPM1mut (OR 2.6; 95%-CI, 1.2–5.5), non-adverse karyotype subsuming core-binding factor and cytogenetically normal AML (OR 2.7; 95%-CI, 1.4–4.9); and age (diff. of 10 years, OR 0.58; 95%-CI, 0.3–1.0). Cox proportional hazard model for OS was performed on patients who were up-front randomized for ATRA. This model revealed a significant interaction between ATRA and the NPM1mut/FLT3-ITDneg genotype, confining the beneficial effect of ATRA to patients in that subgroup (HR, 0.29; 95%-CI, 0.10–0.87). Additional variables were log(LDH) (HR, 2.6; 95%-CI, 1.4 – 4.6), age (HR, 1.6; 95%-CI, 1.2– 2.2) and non-adverse karyotype (HR, 0.7; 95%-CI, 0.5–1.0). Univariable analysis revealed a survival after 5 years in patients with the genotype NPM1mut/FLT3-ITDneg of 57% (95%-CI, 28%–78%) in the ATRA-arm (n=16) compared to only 6% (95%-CI, 0%–25%) in the standard-arm (n=14) (p=0.002). In contrast, there was no difference in survival in all other patients with a survival of 2% (95%-CI, 0%–7%) in both arms (p=0.23). Conclusions: The genotype NPM1mut/FLT3-ITDneg emerges as highly significant predictive factor for response to ATRA in elderly patients with AML. This finding is validated prospectively in the ongoing AMLSG 07–04 study randomizing for ATRA in younger adults (ClinicalTrials.gov Identifier: NCT00151242).