Kurzfassung: Background: Measurable residual disease (MRD), as determined by quantitation of Nucleophosmin 1-mutated (NPM1mut) transcript levels (TL), provides significant prognostic information independent of other risk factors in patients (pts) with acute myeloid leukemia (AML). This is also addressed by the 2017 European LeukemiaNet (ELN) risk stratification system, which recommends taking into account results from MRD monitoring when selecting the appropriate post-remission therapy. Furthermore, MRD monitoring provides a powerful tool to evaluate treatment effects within clinical trials investigating novel therapies. Aims: To determine the impact of the anti-CD33 immunotoxin Gemtuzumab-Ozogamicin (GO) on kinetics of NPM1mut TL in pts with newly diagnosed NPM1mut AML [18 to 82 years (yrs), median age 58 yrs] enrolled in our randomized Phase III AMLSG 09-09 study (NCT00893399). In this study GO was randomized (1:1) to standard chemotherapy plus ATRA. Patients and Methods: In total, 588 evaluable pts were enrolled in the clinical AMLSG 09-09 study. Standard treatment comprised two cycles of induction therapy with A-ICE (ATRA, idarubicin, cytarabine, etoposide; arm A) followed by three consolidation cycles of high-dose cytarabine (n=371, 63%) or allogeneic hematopoietic cell transplantation (n=42, 8%). In the investigational arm (arm B), GO (3 mg/m²) was given at d1 of each induction and in the first consolidation cycle. 296 pts were randomized to arm A and 292 pts to arm B. For this correlative study, outcome analysis was restricted to the clinical endpoint cumulative incidence of relapse (CIR) due to study protocol requirements allowing overall survival analysis to be performed only two years after the last pt had been enrolled. MRD monitoring was performed in a total 503 pts for whom at least one bone marrow (BM) sample was available using RQ-PCR technique; the median follow-up (FU) of the 503 pts was 2.8 yrs. NPM1mut TL (ratio of NPM1mut/ABL1 transcripts x 104) were determined by RQ-PCR (sensitivity 10-5 to 10-6). Results: In total, 3711 BM samples were analyzed (at diagnosis, n=415; during treatment, n=1765; during FU, n=1531). Both study arms were well balanced with regard to pts characteristics and pretreatment NPM1mut TL. First, we evaluated the impact of GO on kinetics of NPM1mut TL during treatment. After the first induction cycle, median NPM1mut TL were significantly lower in the investigational arm (p=.001) and this was true for all subsequent treatment cycles [after induction II (p=.008), consolidation I (p 〈 .001), consolidation II (p=.006), consolidation III (p=.009)]. Next, we evaluated treatment effects on NPM1mut TL after two cycles of induction therapy in pts in complete remission (CR, n=378). At this time point, there was no difference in the proportion of pts achieving RQ-PCR negativity (RQ-PCRneg) [arm A 15% (28/192), vs arm B 17% (32/186); p=.57] between the two treatment arms. However, treatment according to investigational arm B with GO was associated with a significantly lower CIR rate (CIR at 4 yrs: arm B 29% vs arm A 45%, p=.02). In multivariate analysis randomization to arm B revealed as an independent prognostic factor for remission duration (HR 0.63, p=.018). At the end of treatment (EOT, n=288 pts in CR) the proportion of pts achieving RQ-PCRneg was significantly higher (55% vs 41%; p=.02) in the investigational arm; pts treated in arm B had a significantly lower CIR rate compared to arm A (CIR at 4 yrs: arm B 29% vs arm A 45%, p=.04). Conclusion: In our randomized Phase III AMLSG 09-09 study, the addition of GO to intensive chemotherapy plus ATRA was associated with a significantly better reduction of NPM1mut TL after each treatment cycle. This better clearance translated into a significantly lower CIR in the investigational arm with GO. Disclosures Paschka: Otsuka: Membership on an entity's Board of Directors or advisory committees; Bristol-Meyers Squibb: Other: Travel support, Speakers Bureau; Jazz: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Amgen: Other: Travel support; Janssen: Other: Travel support; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Astex: Membership on an entity's Board of Directors or advisory committees; Agios: 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; Takeda: Other: Travel support. Krönke:Celgene: Honoraria. Fiedler:Amgen: Other: support for meetíng attendance; GSO: Other: support for meeting attendance; Teva: Other: support for meeting attendance; Gilead: Other: support for meeting attendance; JAZZ Pharmaceuticals: Other: support for meeting attendance; 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; Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Pfizer: Research Funding; Amgen: Patents & Royalties; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Other: support for meeting attendance. Schroeder:Celgene: Consultancy, Honoraria, Research Funding. Lübbert:Janssen: Honoraria, Research Funding; TEVA: Other: Study drug; Cheplapharm: Other: Study drug; Celgene: Other: Travel Support. Götze:JAZZ Pharmaceuticals: Honoraria; Novartis: Honoraria; Takeda: Honoraria, Other: Travel aid ASH 2017; 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. Schlenk:Pfizer: Research Funding, Speakers Bureau. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Döhner:Amgen: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding; Agios: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Celator: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Seattle Genetics: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Bristol Myers Squibb: Research Funding; Bristol Myers Squibb: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Pfizer: Research Funding; Seattle Genetics: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Sunesis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding.

Kurzfassung: 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.

Kurzfassung: Introduction: With the introduction of reduced-intensity conditioning (RIC), the age limit for allogeneic transplantation of AML patients has risen to 65 and above. In order to balance a low transplant-related mortality (TRM) with high anti-leukemic efficacy, Marks et al.1 introduced FBM conditioning consisting of 150mg/m2 Fludarabine, 300mg/m2 BCNU and 110mg/m2 Melphalan as RIC for elderly patients with encouraging results. However, no detailed analysis of factors predicting outcome in this subpopulation has been presented so far. Methods: In this two-center retrospective study, 51 patients (pts) with a median age of 64 y (range, 44-75y) diagnosed with AML were uniformly treated according to the FBM protocol. GvHD prophylaxis consisted of Ciclosporin A (CYA) and mycophenolate mofetil (MMF) in all patients. MMF was tapered after d50 and CYA after d90 in the absence of GvHD. Pts with matched unrelated donors (MUD) (n=33) or mismatched unrelated donors (MMUD) (n=9) received additional ATG or low dose alemtuzumab as GvHD and rejection prophylaxis. 9 pts with matched related donor (MRD) only received CYA and MMF as GvHD prophylaxis. Stem cell source was peripheral blood in 90% (n=46) and marrow in 10% (n=5) of the patients. The median number of transfused CD34+ cell was 7.1 million per kg body weight. The median follow-up at the time of analysis was 27 months. At the time of transplant 38 pts were in complete remission; the rest of the pts had active disease (partial remission or refractory disease). Molecular (NPM1, FLT3-ITD and CEBPA a) and cytogenetic characteristics (evaluable in 50 patients) were available for all patients. Results: Acute regimen-related toxicity was low, with a d30 mortality of 0 % in both centers. After 2 years, treatment failure was mainly due to relapse (CIR) with 36% (SE: 8%) in comparison to TRM (20%, SE: 7%). The resulting progression-free survival (PFS) and overall survival (OS) at 2 years was 50 % (SE: 5%) and 61% (SE: 7%), respectively. The median EBMT score was 4 (range 2-6). The EBMT score had no impact on different outcome variables (CIR (p=0.465), PFS (p=0.352) and OS (p=0.171)). Based on cytogenetic and molecular data patients were categorized according to the European LeukemiaNet (ELN) classification. 10% (n=5) of the patients belonged to the ELN favorable, 39% (n=20) to the ELN intermediate I, 29% (n=15) to the ELN intermediate II and 22% (n=11) to the ELN adverse risk group. Neither the ELN score itself nor stratification according to FLT3 -ITD or NPM1 mutation status or cytogenetic risk group impacted on outcome in our cohort. A trend for an improved OS in patients with NPM1 mutation (not stratified for FLT3-ITD or FLT3-TKD) was detected (p=0.255). By analyzing further risk factors such as remission status, donor type, age, CMV status, CD34+ cell number and acute or chronic GvHD we found the disease status at the time of transplant being the dominant predictor for OS. After 2 years patients transplanted not in remission had only an OS of 20% (SE: 8%) as compared to 75% (SE: 12%) in patients transplanted in CR (p 〈 0.001) (Figure 1). Conclusion: In this cohort of elderly patients with AML receiving allogeneic transplantation after FBM conditioning, disease status at the time of transplant was the dominant prognostic factor for outcome. At the present follow-up neither molecular status nor cytogenetics impacted OS, PFS or CIR, significantly. We conclude that alternative strategies have to be applied using FBM conditioning in refractory patients, i.e. the early tapering of immunosuppression and the use of donor lymphocytes or cytoreduction immediately before the start of conditioning. An additional focus should be on novel compounds, which might help to increase CR rates at time of transplant. References 1. Marks R, Potthoff K, et al. Reduced-toxicity conditioning with fludarabine, BCNU, and melphalan in allogeneic hematopoietic cell transplantation: particular activity against advanced hematologic malignancies. Blood. 2008;112(2):415-425. Figure 1. Overall survival dependent on disease status at transplant. Figure 1. Overall survival dependent on disease status at transplant. Disclosures No relevant conflicts of interest to declare.

Kurzfassung: Background High-dose chemotherapy followed by autologous stem cell transplant (ASCT) has been the mainstay of first-line treatment in multiple myeloma for nearly two decades. As the majority of patients (pts.) will experience relapse, we continuously are in need of effective salvage strategies such as the era of the “novel agents” is offering. The “next generation” compounds such as pomalidomide or carfilzomib significantly improve prognosis. However, virtually all drug combinations need to be delivered continuously through (subsequent) disease progression, thereby contributing to exhaustion of bone marrow function. This in turn leads to compromised full-dose treatment, which would be necessary to conquer refractory disease. Given these challenges and considering a long interval since the initial exposure to melphalan (Mel) a further autotransplant seems reasonable. Whether a third autotransplant still is effective in patients who have initially received tandem ASCT and may overcome therapy-induced exhausted bone marrow function is unclear. Therefore, we assessed the outcomes of pts. receiving a third melphalan-based salvage ASCT (ASCT3). Methods We queried the databases of six German myeloma centres for cases that were offered a third autotransplant after uniform melphalan-based tandem ASCT as part of their first-line therapies. Results 55 pts. with a median age of 58 years at diagnosis (range, 36 – 72) and of 63 (range, 38 – 77) at ASCT3 were identified. ASCT3 was performed at a median of 63 (range, 14 – 355) months (mos.) from myeloma primary diagnosis and a median interval from initial tandem autotransplant of 51 (range, 5 – 131) mos. Median progression-free survival (PFS) from primary tandem transplant had been 23 mos. (range, 4 – 94). 45 pts. (82%) had either received bortezomib and/or lenalidomide, and 37 pts. both. Eleven pts. had been double refractory and 23 pts. at least had been refractory to one of the novel agents prior to their 3rd transplant. In 45 cases cytogenetic analysis had been available, of which 9.1% could be classified as ”high-risk” (17p13 del, t(4;14), t(14;16), amp1q21, del1p). At ASCT3, median administered Mel-dose had been 100mg/m2 (range, 30-200). 50 pts. received autografts, which had been harvested at first-line treatment while 5 pts. had successfully undergone additional stem cell mobilisation. Median number of re-infused CD34+ cells was 3.0 (range, 0.4 – 15.7) x 10exp6/kg body weight with all patients achieving stable engraftment. A remarkable improvement of platelet count (PLT) and haemoglobin (Hb) within 3 mos. of ASCT3 could be achieved. PLT improvement occurred in 53% and Hb improvement (when compared to pre-ASCT3 values) in 64% of pts. Beyond that, overall response rate (partial response (PR) or better) was 59% with 8 pts. (15%) achieving CR, 6 pts. (11%) VGPR and an additional 18 pts. (33%) PR, respectively. 23 pts. (42%) suffered from grade 3 non-hematologic toxicities and in one case a grade 4 toxicity was documented. Non-relapse mortality (NRM) within 3 mos. after ASCT3 was 5%. Median PFS after ASCT3 was 6 mos. for the whole group and 2 mos. for the group with “high risk” cytogenetics (p=0,06), respectively, whereas median OS (30 mos.) was identical. In case of double-refractory myeloma, PFS did not differ significantly (3 mos. vs. 7 mos., p=0.35) whereas there was a significant difference in median OS (12 mos. vs. 35 mos., p=0.002) in comparison with non-refractory pts., respectively. Conclusions Our analysis indicates that salvage ASCT at late relapse is feasible and associated with a 6 mos.’ additional PFS interval but also contributes to improved hematopoietic function. Pts. may thus tolerate further conventional lines of treatment what is suggested by an OS of 30 mos. In addition, ASCT offers a substantial treatment-free interval when compared to either “next generation” novel drug. In this series, unfavourable cytogenetics were associated with a trend for worse PFS but not OS outcomes, meanwhile being double refractory was linked with clearly inferior OS. Interestingly, median duration of storage of their autografts of 52 mos. (range, 1 – 154) did not impair engraftment after salvage transplant. Disclosures No relevant conflicts of interest to declare.

Kurzfassung: Background: CBF-AML is defined by recurrent genetic abnormalities which encompass t(8;21)(q22;q22), inv(16)(p13.1q22) or less frequently t(16;16)(p13.1;q22). Most frequent secondary chromosome aberrations in t(8;21) AML are del(9q) or loss of a sex chromosome, and in inv(16)/t(16;16) AML trisomy 22 or trisomy 8. At the molecular level mutations involving KIT, FLT3, or NRAS were identified as recurrent lesions in CBF-AML. However, the underlying genetic alterations which might trigger relapse in CBF-AML are not well delineated. Thus, the aim of our study was to characterize the clonal architecture of relapsed CBF-AML. Methods: We performed mutational profiling (KIT, FLT3-ITD, FLT3-TKD, NRAS, ASXL1) in paired samples obtained at diagnosis and at relapse from 66 adults with CBF-AML [inv(16), n=43; t(8;21), n=23] who all were treated within the AMLSG studies. Results: In inv(16) AML, the following mutation pattern was identified at diagnosis: KIT 13/40 (33%; exon 8, n=6; exon 17, n=5; exon 8+17, n=1; exon 11, n=1; missing data, n=3), NRAS 18/43 (42%), FLT3-TKD 4/43 (9%); none of the pts harboured FLT3-ITD or ASXL1 mutations. At the time of relapse, there was a shift in the mutation pattern in 26 pts (60%): KIT mutations (exon 8, n=5; exon 17, n=2; exon 8+17, n=1) were lost in 8 pts and 1 pt acquired an exon 17 KIT mutation; similarly, 15 pts lost and 1 pt gained NRAS mutation, respectively. Of note, all FLT3-TKD mutations were lost at the time of relapse, and only one pt gained a FLT3-ITD mutation. Based on these findings we calculated the stability in inv(16) AML for KIT, NRAS and FLT3-TKD mutations as 38%, 17%, and 0%, respectively. AML with t(8;21) presented a different diagnostic mutation profile: KIT 9/23 (39%; exon 17, n=8; exon 11, n=1), FLT3 -ITD 3/23 (13%), NRAS 2/23 (9%), and ASXL1 1/23 (4%); there were no FLT3-TKD mutations. At the time of relapse, the mutation pattern changed in 9 pts (39%); KIT mutations were lost in 4 pts (exon 17, n=3; exon 11, n=1), but acquired in 2 pts with both of them located in exon 17; only 1 pt lost the NRAS mutation. FLT3-ITD was lost in 2 and gained in 3 pts. There was no change in the ASXL1 mutation status. Thus, the stability for KIT, NRAS, FLT3-ITD and ASXL1 mutations in t(8;21) AML was calculated as 56%, 50%, 33% and 100%, respectively. Of note, mutations affecting the KIT and NRAS gene were almost mutually exclusive; there were only 3 pts with concurrent KIT and NRAS mutations at diagnosis [inv(16), n=2; t(8;21), n=1] . Conclusion: CBF-AML cases display a high degree of molecular heterogeneity with shift of the mutation pattern at relapse in both CBF-AML subtypes. The frequent loss of KIT and NRAS mutations at relapse suggests that there might be other important secondary lesions driving relapse. Ongoing high-resolution genome-wide profiling will further unravel the clonal hierarchy and genomic landscape in CBF-AML. Disclosures Götze: Novartis: Honoraria; Celgene Corp.: Honoraria. Greil:Celgene: Consultancy; Ratiopharm: Research Funding; Sanofi Aventis: Honoraria; Pfizer: Honoraria, Research Funding; Boehringer-Ingelheim: Honoraria; Astra-Zeneca: Honoraria; GSK: Research Funding; Novartis: Honoraria; Genentech: Honoraria, Research Funding; Janssen-Cilag: Honoraria; Merck: Honoraria; Mundipharma: Honoraria, Research Funding; Eisai: Honoraria; Amgen: Honoraria, Research Funding; Cephalon: Consultancy, Honoraria, Research Funding; Bristol-Myers-Squibb: Consultancy, Honoraria; AOP Orphan: Research Funding; Roche, Celgene: Honoraria, Research Funding. Schlenk:Boehringer-Ingelheim: Honoraria; Teva: Honoraria, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Research Funding; Arog: Honoraria, Research Funding.

Kurzfassung: Background: Nucleophosmin (NPM1mut) mutations represent one of the most common gene mutations in acute myeloid leukaemia (AML) and can be used for monitoring minimal residual disease (MRD). In a former study, we could define clinical relevant check-points and a cut-off value to identify patients (pts) at high risk of relapse. Aims: To confirm our previous results on the clinical relevance of NPM1mut transcript levels (TL) in an extended cohort of younger AML pts (18 to 60 years) harbouring NPM1mut type A, B, C, D, JT, 4, QM, NM or KM, and to assess the impact of concurrent FLT3 internal tandem duplications (ITD) and DNMT3A (DNMT3Amut) mutations on NPM1mut TL kinetics. Methods: All pts were enrolled in one of four AMLSG [AMLHD98A (n=46; NCT00146120); AMLSG 07-04 (n=199; NCT00151242); AMLSG 09-09 (n=179; NCT00893399); AMLSG 16-10 (n=75; NCT01477606)] treatment trials. Treatment comprised double induction therapy (DI) with ICE (idarubicin, cytarabine, etoposide) with or without ATRA or gemtuzumab ozogamicin, or 1 cycle of daunorubicin and cytarabine followed by 1 to 4 cycles of high-dose cytarabine (n=292), autologous (n=19) or allogeneic stem cell transplantation (n=141). NPM1mut TL (ratio of NPM1mut/ABL1 transcripts x 104) were determined by RQ-PCR using TaqMan technology; the sensitivity of the assays was 10-5 to 10-6. DNMT3A and FLT3 -ITD (FLT3 -ITDmut) mutation status was assessed by standard PCR-based methods. Results: A total of 2835 samples from 499 NPM1mut pts were analysed at diagnosis (n=439), after each treatment cycle (n=1394) and during follow-up (FU) (n=1002). Peripheral blood (PB) samples were only included in the advanced FU period (defined as at least 12 months after completion of therapy). NPM1mut TL at diagnosis varied between 7.03 x103 and 2.38 x 107 (median 5.37 x 105). Pretreatment NPM1mut TL were not associated with clinical characteristics (e.g., age, WBC, BM blasts, FLT3 -ITDmut, DNMT3Amut) with the exception of LDH level (p=0.006) and did not impact event-free survival (EFS), relapse-free (RFS) and overall survival (OS). NPM1mut TL as log 10 transformed continuous variable at different time points during therapy were significantly associated with shorter remission duration (RD) and shorter OS. After DI therapy, the cumulative incidence of relapse (CIR) at 4 years was 10% for RQ-PCR-negative pts (n=41) versus 45% for RQ-PCR-positive pts (n=226) (p 〈 0.0001); the lower CIR translated into a significant better OS (92% versus 60%, respectively; p=0.001). After completion of therapy, CIR at 4 years was 13% for RQ-PCR-negative pts (n=126) and thus significantly lower compared with 56% in RQ-PCR-positive pts (n=139; p 〈 0.00001). Again, the lower CIR translated into a significantly better OS (81% versus 55%, respectively; p 〈 0.00001). Multivariable analysis performed at both time points showed that NPM1mut TL were significantly associated with a shorter RD (HR, 1.86; 2.30, respectively) and shorter OS (HR, 1.58; 1.72, respectively). During FU, 1002 bone marrow (BM) and PB samples from 280 pts were analysed. The relapse rate at 2 years for pts exceeding the previously defined cut-off value of 〉 200 NPM1mut copies was 90% with a median time to relapse of 1.38 months. In contrast, only 6/104 pts with sustaining RQ-PCR negativity relapsed. Finally, we evaluated the impact of concurrent FLT3 -ITDmut and DNMT3Amut on kinetics of NPM1mut TL. Following the first induction cycle, the median NPM1mut TL was significantly lower in pts with the NPM1mut/FLT3 -ITDwildtype/DNMT3Awildtype genotype compared to pts with the genotype NPM1mut/FLT3 -ITDmut/DNMT3Amut. This effect could be observed throughout subsequent treatment cycles. Conclusions: The results of our analysis on an extended cohort of younger AML pts with NPM1mut highly confirmed the two clinically relevant MRD check-points, after DI and after completion of therapy; during the FU period, exceeding a cut-off value of 〉 200 TL was highly predictive for relapse. Finally, we found a significant impact of concurrent FLT3 -ITDmut/DNMT3Amut on the kinetics of NPM1mut TL. Disclosures Fielder: Amgen: Other: Congress Participation; Teva: Other: Congress Participation; Kolltan: Research Funding; Amgen: Research Funding; Pfizer: Research Funding; Astellas: Other: Congress Participation. Horst:Boehringer Ingleheim: Research Funding; MSD: Research Funding; Pfizer: Research Funding; Gilead: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Götze:Celgene Corp.: Honoraria; Novartis: Honoraria. Schlenk:Pfizer: Honoraria, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Teva: Honoraria, Research Funding; Boehringer-Ingelheim: Honoraria; Arog: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees.

Kurzfassung: 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), implicating FLT3 as a potential target for kinase inhibitor therapy. The multi-targeted kinase inhibitor midostaurin shows potent activity against FLT3 as a single agent but also in combination with intensive chemotherapy. Aims: To evaluate the feasibility and efficacy of midostaurin in combination with intensive induction therapy and as single agent maintenance therapy after allogeneic hematopoietic stem cell transplantation (alloHSCT) or high-dose cytarabine (HIDAC). Methods: The study includes 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 (NCT: NCT01477606). Pts with acute promyelocytic leukemia are not eligible. The presence of FLT3-ITD is analyzed within our diagnostic study AMLSG-BiO (NCT01252485) by Genescan-based fragment-length analysis (allelic ratio & gt;0.05 required to be FLT3-ITD positive). Induction therapy consists of daunorubicin (60 mg/m², d1-3) and cytarabine (200 mg/m², continuously, d1-7); midostaurin 50 mg bid is applied from day 8 onwards until 48h before start of the next treatment cycle. A second cycle is optional. For consolidation therapy, pts proceed to alloHSCT as first priority; if alloHSCT is not feasible, pts receive three cycles of age-adapted HIDAC in combination with midostaurin from day 6 onwards. In all pts maintenance therapy for one year is intended. This report focuses on the first cohort of the study (n=149) recruited between June 2012 and April 2014 prior to the amendment increasing the sample size; the amendment to the study is active since October 2014. Results: At study entry patient characteristics were median age 54 years (range, 20-70, 34% ≥ 60 yrs); median white cell count (WBC) 48.4G/l (range 1.1-178G/l); karyotype, n=103 normal, n=3 t(6;9), n=2 t(9;11), n=20 intermediate-2 and n=7 high-risk according to ELN recommendations, n=14 missing; mutated NPM1 n=92 (62%). Data on response to first induction therapy were available in 147 pts; complete remission (CR) 58.5%, partial remission (PR) 20.4%, refractory disease (RD) 15% and death 6.1%. A second induction cycle was given in 34 pts. Overall response after induction therapy was CR 75% and death 7.5%. Adverse events 3°/4° reported during the first induction cycle were most frequently gastrointestinal (n=34) and infections (n=81). During induction therapy midostaurin was interrupted, dose-reduced or stopped in 55% of the pts. Overall 94 pts received an alloHSCT, 85 in first CR (n=65 age & lt;60 yrs, n=20 age ≥60 yrs) and 9 pts after salvage outside the protocol or after relapse (n=70 from a matched unrelated and n=24 from a matched related donor). In pts receiving an alloHSCT within the protocol in median 2 chemotherapy cycles were applied before transplant (range 1-4) and the cumulative incidence of relapse and death at 12 months were 9.2% (SE 3.3%) and 19.5% (SE 4.8%). Maintenance therapy was started in 52 pts, 40 pts after alloHSCT and 12 pts after HIDAC. Only 4 adverse events 3°/4° were attributed to midostaurin. First analyses revealed a low cumulative incidence of relapse irrespective of the FLT3-ITD mutant to wildtype ratio ( & lt;0.5 versus ≥0.5) in patients proceeding to alloHSCT with 12% and 5% as well as for those after HIDAC consolidation with 28% and 29%, respectively. Conclusions: The addition of midostaurin to intensive induction therapy and as maintenance after alloHSCT or HIDAC is feasible and compared to historical data may be most effective in those patients with a high FLT3-ITD mutant to wildtype ratio. Disclosures Schlenk: Novartis: Honoraria, Research Funding. Salwender:Celgene: Honoraria; Janssen Cilag: Honoraria; Bristol Meyer Sqibb: Honoraria; Amgen: Honoraria; Novartis: Honoraria. Götze:Celgene Corp.: Honoraria; Novartis: Honoraria.