Abstract: BACKGROUND AND OBJECTIVES: Chemosensitization using plerixafor combined with FLAG-IDA (PLERIFLAG regimen) showed promising results (48% CR/CRi) in a phase 2 trial for primary refractory and early relapsed (duration of first CR & lt;12 months) Adult AML patients. We aim to compare retrospectively results of the PLERIFLAG cohort versus historical cohorts of patients salvaged with FLAG-IDA (Fludarabine, Idarubicine, Cytarabine, G-CSF as priming agent), or FLAGO-IDA (Gemtuzumab plus FLAG-IDA) registered in the PETHEMA epidemiologic AML registry (NCT02006004). To match different cohorts, we used two risk-score classifications: EPI/HOVON (De Breems, JCO 2005) and SALFLAGE (Bergua, BJH 2016). The purpose is to analyse the complete remission (CR+CRi) rate, the rate of patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT). The disease-free survival (DFS) and overall survival (OS) were adjusted using established risk factors (time to relapse (TTR), karyotype, FLT3-ITD, previous stem cell transplant (SCT)) using propensity score analysis. Patients: Of the 540 patients in the data base we analysed 300 patients relapsed or resistant to induction therapy, which had all data available. 241 patients were treated with FLAG-IDA, 41 with FLAGO-Ida, and 42 with PLERIFLAG. Differences between treatment cohorts were tested using Fisher exact test. Treatment cohorts (PLERIFLAG vs FLAG-IDA vs FLAGO-IDA) were similar in Age (p=0.5), Sex (p=0.5), FLT3-ITD mutated (p=0.5), EPI/HOVON cytogenetics score (p=0.5) and previous myelodisplasia (p=0.2). The three cohorts differed in time to relapse (p=0.001), previous stem cell transplantation (0.001), HOVON score (p=0.03) and SALFLAGE score (0.001). RESULTS There were no differences in terms of CR+CRi between the three types of treatment adjusted by Hovon risk score (Pleriflag: 48%, FLAG-IDA: 50% or FLAGO-IDA: 58%; Chrochan Maentel-Haenszel test, p=0.466) or SALFLAGE score (Chrochan-Maentel-Haenszel test, p=0.23). More patients were allografted in the PLERIFLAG (61%) group even not achieving CR/Cri, as compared to FLAG-IDA (38%) or FLAGO-Ida (61% vs 38% vs. 18%, p=0.0001). To compare PLERIFLAG against the other two types of salvage treatment we performed a Propensity Score in a proportion 1:3. We adjust variables like age, previous allogeneic transplant, time to relapse (refractory, & lt;12 months and & gt;12 months), karyotype using MRC, and FLT3-ITD status. Karyotype risk was considered by HOVON criteria (inv16, t(8;21) vs others), and SALFLAGE (inv 16, intermediate risk, and unfavourable risk by MRC risk plus t(8;21)). The propensity score analyses showed that Compared to FLAG-IDA, PLERIFLAG was associated to increased survival (median OS 10.56 months vs. 5.6, p=0.03), but not improved EFS (2.83 months vs 1.41 months, p=0.8). The benefit in OS but not in EFS could be explained in part by frequent use of Allo SCT in patients who had not achieve CR/CRi in the PLERIFLAG cohort. In conclusion, our historical control study show that PLERIFLAG regimen is an acceptable therapeutic option for first relapsed/refractory adult AML patients. Disclosures Esteve: Jazz Pharmaceuticals: Consultancy; Amgen: Consultancy; Pfizer: Consultancy; Novartis: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Consultancy; Roche: Consultancy; Astellas: Consultancy, Speakers Bureau. Salamero:Novartis: Honoraria; Pfizer: Honoraria; Celgene: Honoraria; Daichii Sankyo: Honoraria. Perez Encinas:CELGENE: Consultancy; JANSSEN: Consultancy; GILEAD SCIENCES: Research Funding. Montesinos:Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research support, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research support, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Other: Research support; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Teva: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau.

Abstract: Introduction: Recent studies have shown that young to middle-aged adults who receive a pediatric-inspired chemotherapy regimen for treatment of Ph-neg ALL do not appear to require an alloHSCT if they achieve good response on MRD testing after induction and/or consolidation therapy. Patients (pts) who are not good MRD responders achieve better outcomes with alloHSCT than their counterparts who do not receive alloHSCT. However, it is not clear if this approach can specifically apply to adult ALL pts with HR features at baseline. The aim of the prospective ALL-HR-11 trial (NCT01540812) from the Spanish PETHEMA Group was to evaluate response of HR Ph-neg adult ALL patients to a different post-induction therapy (chemotherapy or alloHSCT) according to MRD levels (centrally assessed by 8-color flow cytometry [FCM] ) at the end of induction (week 5) and consolidation therapy (week 17).. Patients and methods: HR ALL included one or more of the following parameters at baseline: age 30-60y, WBC count & gt;30x109/L for B-cell precursor ALL or & gt;100x109/L for thymic T-ALL, pro-B, early or mature T-ALL, 11q23 or KMT2A rearrangements or complex karyotype. Induction therapy included vincristine, prednisone, daunorubicin and asparaginase (E coli native or PEG according to center availability) for 4 weeks (Induction-1). FLAG-Ida was administered as intensified induction (Induction-2) in pts not achieving CR or in those in CR with MRD≥0.1% at the end of induction. For pts in CR and MRD & lt;0.1% early consolidation therapy included 3 cycles with rotating cytotoxic drugs with high-dose methotrexate, high-dose ARA-C and high-dose asparaginase (E coli native or PEG). These pts continued with delayed consolidation (identical to that of early consolidation) followed by maintenance therapy up to 2y in CR if MRD levels after consolidation were & lt;0.01%; otherwise they were assigned to alloHSCT. Pts in CR after Induction-2 received one consolidation cycle and were assigned to alloHSCT. Main outcome measures were: complete response (CR), overall survival (OS) and cumulative incidence of relapse (CIR), assessed by competing risk analysis. Results: On April 2019, 307 HR ALL pts were evaluable. Median (range) age was 40 (15-60) y, 192 were males, 211 precursor B-ALL and 96 T-ALL, with a median WBC count of 12.9 (0.2-564) x109/L. Results of Induction-1 (n=304, 3 on induction): therapy-related death: 12(4%), resistance: 39(13%), CR: 253(83%). MRD & lt;0.1% at the end of induction was observed in 77% of CR patients. Induction-2 was administered to 88 patients (due to no CR: 37, or to CR and MRD≥0.1%: 51). Overall response rate: 277 (91%). The 5y CIR and OS probabilities for the whole series were of 44%±8% and 48%±7% (median follow-up: 2.06y [range: 0-7.55y]). By intention-to treat after Induction-1, 94 pts were assigned to alloHSCT and 190 to delayed consolidation and maintenance. The 5y CIR and OS probabilities were of 37%±13% and 38%±11%, respectively, for pts assigned to alloHSCT, and of 48%±10% and 55%±10%, respectively, for those assigned to chemotherapy (P & lt;0.001 for OS [Figure 1], and P=0.243 for CIR). Patients with MRD & lt;0.1% at the end of induction and MRD & lt;0.01% at the end of consolidation (n=137) showed a 5y CIR and OS of 42%±11% and 66%±11%, respectively (P & lt;0.001 for both, Figure 2). Patients with MRD levels & lt;0.01% on day14 of induction-1, end-induction-1 and end-consolidation (n=17) showed 5y CIR and OS probabilities of 17%±19% and 90%±19%, respectively. Conclusions: This trial, in which post-induction therapy was only based on MRD results assessed by FCM, suggests that avoiding alloHSCT does not hamper the outcome of HR Ph-neg adult ALL pts with adequate MRD response after induction and after consolidation. Better post-remission alternative therapies are specially needed for patients with poor MRD clearance. Supported by grants PI14/01971 FIS, Instituto Carlos III, and SGR225 (GRE), Spain. Disclosures Montesinos: Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Teva: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research support, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research support, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Other: Research support; Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau. Esteve:Novartis: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy; Pfizer: Consultancy; Astellas: Consultancy, Speakers Bureau; Amgen: Consultancy; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Consultancy; Jazz Pharmaceuticals: Consultancy.

Abstract: The need for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in adults with Philadelphia chromosome–negative (Ph−) acute lymphoblastic leukemia (ALL) with high-risk (HR) features and adequate measurable residual disease (MRD) clearance remains unclear. The aim of the ALL-HR-11 trial was to evaluate the outcomes of HR Ph− adult ALL patients following chemotherapy or allo-HSCT administered based on end-induction and consolidation MRD levels. Patients aged 15 to 60 years with HR-ALL in complete response (CR) and MRD levels (centrally assessed by 8-color flow cytometry) & lt;0.1% after induction and & lt;0.01% after early consolidation were assigned to receive delayed consolidation and maintenance therapy up to 2 years in CR. The remaining patients were allocated to allo-HSCT. CR was attained in 315/348 patients (91%), with MRD & lt;0.1% after induction in 220/289 patients (76%). By intention-to-treat, 218 patients were assigned to chemotherapy and 106 to allo-HSCT. The 5-year (±95% confidence interval) cumulative incidence of relapse (CIR), overall survival (OS), and event-free survival probabilities for the whole series were 43% ± 7%, 49% ± 7%, and 40% ± 6%, respectively, with CIR and OS rates of 45% ± 8% and 59% ± 9% for patients assigned to chemotherapy and of 40% ± 12% and 38% ± 11% for those assigned to allo-HSCT, respectively. Our results show that avoiding allo-HSCT does not hamper the outcomes of HR Ph− adult ALL patients up to 60 years with adequate MRD response after induction and consolidation. Better postremission alternative therapies are especially needed for patients with poor MRD clearance. This trial was registered at www.clinicaltrials.gov as # NCT01540812.

Abstract: Introduction In the last years genome wide profilings have identified recurrent Copy Number Alterations (CNA) in genes potentially involved in the pathogenesis of Acute Lymphoblastic Leukemia (ALL). These studies have identified deletions in B-cell development genes (IKZF1, EBF1, PAX5, TCF3, etc.), cell cycle regulation genes (CDKN2A/B, RB1, TP53, etc.), glucocorticoid resistance genes (BTG1, CREBBP) and growth factor receptors genes (CRLF2, CSF2RA, IL3RA) among others. Some of these CNA (i.e. IKZF1, CDKN2A, CRLF2) have been reported to have prognostic significance in several pediatric series but there are very few data regarding their impact in B-lineage adult ALL. Our aim was to analyze the frequency and prognostic significance of CNA in a series of 125 B-lineage adult ALL patients treated according to risk-adapted protocols from the Spanish PETHEMA Group. Methods Bone marrow or peripheral blood (with significant blast burden) samples from 125 B-lineage adult ALL patients enrolled in risk-adapted protocols from the PETHEMA Group were analyzed at diagnosis. MLPA assays (MRC-Holland) were performed for the following genes: IKZF1, IKZF2, IKZF3, EBF1, CDKN2A/B, PAX5, ETV6, BTG1, RB1, hsa-miR-31, X/Y PAR1 region genes (CRLF2, CSF2RA, IL3RA) and 14q32.33 region genes (IGH D, MTA1, KIAA0284). Fragment analysis was made by Genescan in an ABI-3130 sequencer (Applied Biosystems). Data normalization provided a value indicative of the presence or absence of CNA: 0-0.20 homozygous deletion, 0.21-0.70 heterozygous deletion, 0.71-1.30 normal, 1.31-1.70 heterozygous duplication and 1.71-2.20 homozygous duplication. Results The median age [range] was 40 [15-74] years, 71 (57%) males, median WBC count 12.11 x109/L [0.4-388]. Immunophenotype: pro-B 14 (11%), common 71 (58%), pre-B 26 (21%), mature-B 10 (8%), unavailable 2 (2%). Cytogenetics: normal 16 (13%), hyperdiploid 6 (5%), hypodiploid 2 (2%), t(9:22) 20 (16%), t(1;19) 8 (6%), 11q23/MLL 11 (9%), 8q24/C-MYC 7 (5%), complex 1 (1%), iAMP21 2 (2%), other translocations or deletions 31 (25%), no growth 20 (16%). CNA frequencies of the 125 patients are shown in the table. IKZF1 deletions were significantly associated with EBF1 deletions, high WBC count and Philadelphia (Ph) chromosome. In the IKZF1 deleted cohort whole gene deletions were as frequent as Ik6 isoforms (28% each). A high codeletion rate was detected in genes located in 9p (CDKN2A/B with PAX5, CDKN2A/B with hsa-miR-31 and PAX5 with hsa-miR-31). CDKN2A/B also showed concomitant deletions with ETV6 while PAX5 showed codeletions with BTG1. CDKN2A/B and PAX5 deleted patients had higher WBC counts than non-deleted individuals. Clinical follow-up data was available for 123 patients of the whole series and for the 105 patients of the Ph-negative cohort. Multivariate analysis showed that advanced age, BTG1 deletions and EBF1 deletions were negative prognostic factors for achieving Complete Remission (CR) and WBC count and IKZF1 deletions significantly reduced CR duration in both cohorts. Interestingly, there were significant differences in relapse rates between whole and partial gene IKZF1 deletions. IKZF1 haploinsufficient patients had a probability of CR duration at 3 years of 83% ± 30% vs. 6% ± 12% of partial gene deletion carriers. Advanced age and IKZF1 deletions were predictors for overall survival in the Ph-negative cohort and age 〉 30 years, IKZF1 deletions and hsa-miR-31 deletions were associated with poor prognosis in the whole series. Conclusions In B-lineage adult ALL, deletions of IKZF1, EBF1, BTG1 or hsa-miR-31 are markers with prognostic significance in addition to age and WBC count. Patients with partial IKZF1 gene deletions have a significantly higher probability of relapse than those with whole gene loss. These genetic abnormalities could help to better define prognostic subgroups in adult patients with B-lineage ALL. Supported by the grants PI10/01417 and RD12-0036-0029 from Instituto Carlos III and a grant from the Spanish Society of Hematology and Hemotherapy (2012). Disclosures: No relevant conflicts of interest to declare.

Abstract: Background and objective. The combination of HyperCVAD and ponatinib resulted in a high molecular response rate and survival in adults with Ph+ ALL, suggesting improved outcome compared with combinations of chemotherapy with first- or second-generation tyrosine kinase inhibitors (TKI) (Jabbour E, et al, Lancet Haematol. 2018;5:e618-e627). The Spanish PETHEMA group conducted the phase 2 PONALFIL trial, which incorporates ponatinib to the same chemotherapy as that of the ALL Ph08 trial that used imatinib as TKI (Ribera JM et al. Cancer 2019;125:2810-17). Final results of this trial are reported. Patients and method. PONALFIL trial (NCT02776605) combined ponatinib (30 mg/d) and induction chemotherapy (vincristine, daunorubicin, prednisone) followed by consolidation (high-dose methotrexate, high-dose ARA-C, mercaptopurine, etoposide) and allogeneic hematopoietic stem cell transplantation (alloHSCT). Ponatinib was scheduled after alloHSCT only for patients (pts) with persistence/reappearance of MRD. Response to therapy (complete morphological [CR], molecular [complete -CMR- or major -MMR-] after induction and before alloHSCT) (assessed by centralized BCR-ABL1/ABL1 ratio), disease-free survival (DFS), overall survival [OS]) and toxicity were analyzed. The following genetic studies were performed: 1. Additional gene abnormalities (Copy Number Alteration [CNA] analysis by SNP array Affymetrix 750K), 2. ABL1 mutation status at diagnosis (Sanger sequencing), 3. T315I mutation at diagnosis (allele-specific PCR). A propensity score comparison with the results of the ALL Ph08 trial was performed. Results. Median age was 49 (19-59) years (y), and 13/30 pts were female. One pt showed CNS involvement at diagnosis. ECOG score was & lt;2 in 90% of pts. Median WBC count was 6.4 x10 9/L (0.6-359.3), Hb 90 g/L (63-145), platelets 38 x10 9/L (11-206). Immunologic phenotype was common in 26 cases, with p190 isoform in 20 pts (67%), p210 in 9 (30%) and p230 in 1 (3%). CR was attained in 30/30 pts, CMR in 14/30 (47%), MMR in 5/30 (17%) and no molecular response in 11/30 (37%). Two pts withdrew the trial during induction (thrombosis of central retina artery and severe intestinal infection, one case each). Consolidation was given to 28 pts, 2 pts withdrew the trial (physician's decision and lack of molecular response, one case each) and 26 pts received alloHSCT (20 in CMR, 6 in MMR). No relapses before HSCT were detected. One pt died by severe GVHD and two withdrew the trial (grade IV hepatic toxicity:1, protocol deviation after molecular relapse:1). One pt relapsed in BM after HSCT. Ponatinib was given after HSCT in 4/26 pts and dasatinib in 1/26 due to MRD reappearance, and 1/26 received dasatinib in CMR because of refusal to receive CNS prophylaxis, whereas 20/26 pts did not receive any TKI therapy after HSCT. Twenty-nine pts are alive (median follow-up 2.3y, range 1.3-4). 2y DFS and OS probabilities were 97% (91%-100%) and 97% (91%-100%) (Figure 1). Among 7/16 pts without CMR after consolidation and genetic material available, 4 showed IKZF1 deletion (IKZF1 plus in 2), 1 showed CDKN2A/B and PAX5 deletion and 2 did not show any CNA. Among 5/19 pts with molecular relapse, 3 showed IKZF1 deletion (1 being IKZF1 plus), and 2 pts did not show any CNA. No ABL1 mutations or T315I mutation at diagnosis were found. Propensity score with 1:1 matching identified 30 pts in each cohort (variables: age, gender, ECOG, WBC, CNS involvement, cytogenetic risk and BCR/ABL isoform). 2y DFS rates for PONALFIL and ALL Ph08 trials were 97% and 62%, (p=0.005), and 2y OS rates were 97% and 66% (p=0.001) (Figure 2). 107 adverse events (AE) were registered in 20 pts (21 severe in 11 pts), prompting to withdrawn of the trial in 3 (thrombosis of central retina artery, severe bowel infection, grade IV hepatic toxicity). The most frequent AE were hematologic (28%), gastrointestinal (14%), hepatic (11%), infections (7%), and cutaneous (5%). Cardiovascular events occurred in 2 patients (angor pectoris and thrombosis of central artery of the retina). Conclusions. The results of the PONALFIL trial show a high antileukemic efficacy with acceptable toxicity profile and compare favorably with the same chemotherapy schedule and imatinib. Supported in part by grant 2017 SGR288 (GRC) Generalitat de Catalunya and "La Caixa" Foundation. Figure 1. OS (A) and DFS (B). PONALFIL. Figure 2. OS (A) and DFS (B). PONALFIL vs. ALL Ph08. Figure 1 Figure 1. Disclosures Ribera: AMGEN: Consultancy, Research Funding, Speakers Bureau; NOVARTIS: Consultancy, Speakers Bureau; TAKEDA: Consultancy, Research Funding, Speakers Bureau; ARIAD: Consultancy, Research Funding, Speakers Bureau; SHIRE: Consultancy, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau. Esteve: Novartis: Consultancy, Research Funding; Pfizer: Consultancy; Abbvie: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Novartis: Research Funding; Jazz: Consultancy; Astellas: Consultancy. Mercadal: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead Sciences, Inc.: Honoraria, Speakers Bureau. Martínez-López: Roche, Novartis, Incyte, Astellas, BMS: Research Funding; Janssen, BMS, Novartis, Incyte, Roche, GSK, Pfizer: Consultancy. OffLabel Disclosure: This trial includes Ponatinib in off-label indication.

Abstract: INTRODUCTION The hypomethylating agents (HMAs), decitabine (DEC) and azacitidine (AZA), have made it possible to treat more elderly patients with acute myeloid leukemia (AML). Both HMAs have demonstrated efficacy in monotherapy and in combination with targeted therapies. However, there is little direct comparative data on AZA and DEC in first-line treatment, and we do not know which group of patients might benefit from each drug. Results of the full analysis set (FAS) were presented previously (Labrador J, et al. ASH 2020). Here, we report long-term clinical efficacy from prespecified patient subgroup analyses. METHODS We conducted a retrospective study to compare real-life clinical outcomes between AZA and DEC in patients with AML ineligible for intensive chemotherapy included in the PETHEMA registry, and analyzed clinical variables associated with response and overall survival (OS) between AZA and DEC. RESULTS A total of 626 patients were included for the FAS between 2006 and 2019. 487 (78%) received AZA and 139 (22%) received DEC. Baseline characteristics were comparable in both groups, except for the percentage of bone marrow blasts (44% vs. 34% in the DEC group compared to AZA, p=0.010). In the FAS, there was no difference in the CR, CR/CRi or ORR (CR/RCi + PR) rate: 18%, 20.5% and 32% with AZA vs. 23%, 25% and 39.5% with DEC (p=0.20, p=0.27 and p=0.12). In the subgroup analysis, DEC was associated with higher CR/CRi rate than AZA in patients with ECOG ≥ 2 (95% CI: 0.088 - 0.801), bone marrow blast count & lt; 50% (95% CI: 0.293 - 0.965), secondary AML (95% CI: 0.223 - 0.918) and adverse cytogenetics (95% CI: 0.171 - 0.857) (Figure 1A). DEC was associated with higher ORR rate than AZA in patients with ECOG ≥ 2 (95% CI: 0.116 - 0.782), leukocytes & lt; 10 x10 9/L (95% CI: 0.321 - 0.920) and bone marrow blasts & lt; 50% (95% CI: 0.321 - 0.920) (Figure 1B) 120 days-mortality was 25.4% after AZA and 27.1% after DEC, p=0.70. Patients who did not achieve at least a PR had significantly higher 120-day mortality with both HMAs (OR 8.85 and 8.22 for AZA and DEC, respectively). In the subgroup analysis, patients with leukocytes ≥ 10 x10 9/L (95% CI: 1.069 - 4.157) and those with estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73m 2 (95% CI: 1.249 - 4.664) had higher 120-day mortality with DEC than with AZA (Figure 1C) With a median follow-up of 12 months, median OS was 10.4 months (95% CI: 9.2 - 11.7) for AZA vs. 8.8 months (95% CI: 6.7 - 11.0) for DEC (p = 0.455). The subgroup analysis revealed that patients ≥ 80 years (95%: CI 1.005 - 2.341), with leukocytes ≥ 10 x10 9/L (95% CI 1.039 - 2.062), platelet count & lt;20 x10 9/L (95% CI: 1.150 - 3.422) and those with eGFR ≥ 45 mL/min/1.73m 2 (95% CI: 1.040 - 2.059) did benefit for treatment with AZA compared to DEC (Figure 1D). CONCLUSIONS Our study provides real-life data on the outcomes of AML patients treated with AZA compared to DEC in a large retrospective cohort with long-term follow-up. In addition, we identify for the first time some baseline characteristics that could benefit from AZA or DEC in terms of responses, 120-day mortality and OS. These findings could help us to choose the most appropriate HMA in monotherapy or for the development of new combinations. Figure 1 Figure 1. Disclosures de la Fuente: Novartis: Research Funding; Abbie: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau. Tormo: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Pérez-Simón: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Montesinos: Forma Therapeutics: Consultancy; Tolero Pharmaceutical: Consultancy; Karyopharm: 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, Research Funding, Speakers Bureau; Pfizer: 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; 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; Glycomimetics: Consultancy; Agios: Consultancy; Stemline/Menarini: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; 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.

Abstract: Background: Phase I clinical trial for oncology drugs have the highest clinical failure rate. Drug candidates may be discarded if they don´t show activity. Yet these drugs may have valuable activity in patient subgroups. Biomarkers attempt to identify these sensitive subpopulations, but are normally evaluated and validated in Phase II when good drugs may have been discarded. OPB-111077 is a novel, oral, low-molecular-weight compound that inhibits STAT3 and mitochondrial electron transport. A prior Phase I trial on 145 patients from all tumor types gave only 1 partial response (PR). A strong anti-proliferative activity was identified in Acute Myeloid Leukemia (AML) samples ex vivo. This new biomarker was used for patient selection in this trial. We present a novel design of a Phase Ib trial directly selecting patients with a potential biomarker, that can benefit the patient without increasing toxicity risks, in Relapsed/Refractory (RR) AML patients. Method: This is an open-label, phase Ib dose-escalation clinical trial to evaluate the safety profile, maximum tolerated dose (MTD) and preliminary efficacy of oral OPB-111077 in AML relapsed or refractory to chemotherapy patients. Patients & gt; 18 years old with high risk AML, ECOG ≤2 and adequate organ functions were selected for biomarker screening. Biomarker consisted on a dose response curve for antiproliferative activity of agent in a bone marrow sample of patients incubated 72-96-120h (Figure), quantified as the Area Under the Curve (AUC). Patient samples whose ex vivo biomarker showed low sensitivity (70% worst) we excluded, since they were potentially predicted as resistant to the agent. The remaining 30% with higher sensitivity were included. OPB-111077 was administered orally on a once daily dose schedule in 28-day cycles until intolerable toxicity or disease progression. Two dose schemas were evaluated: 200 (DL1) and 250 mg/day (DL2). Dose limiting toxicities were any Grade ≥ 3 non-hematologic toxicity and any unexpected non-tolerable grade II that requires delay beyond 1 week until recovery and evaluated during the first 28 days of treatment. Adverse events were graded according to NCI-CTCAE vs 4.03 and response criteria was based on those given by Cheson et al. IC50 and area under the curve (AUC) determined by the Vivia ex vivo biomarker were correlated with clinical response. Results: We screened 47 RR AML patients, twelve patients were included and selected by personalized medicine test (5 in DL1 and 7 in DL2), median age 76 years, 92% men, 42% ECOG 0 were included in the study. AML patients were refractory in 41.7% and patients were in median of relapses 2 (range 1-6). No DLT was reported. Adverse events related to study treatment were reported in three patients, all G 1-2: in DL1 one patient had vomiting; in DL2 one patient had extrasystoles and other had anorexia, diarrhoea, epigastric discomfort, nausea and vomiting. Two patients died during study treatment due to disease progression and respiratory infection. Half of the patients discontinued study treatment due to disease progression and 25% due to adverse events (respiratory failure G5, respiratory infection G5 and extrasystoles G2). Over the 6 patients evaluable for efficacy, 3 of them achieved PR and 3 treatment failure as best response. Progression free survival and overall survival were 57 days (95% CI: 37 - 77) and 95 days (95% CI: 27 - 163) respectively. The biomarker AUC and IC50 values stratified patients consistent with their clinical response, although without enough sampling potency for statistical significance. Figure shows the relative position of patients included in the study in the context of the overall population of samples considered to build up the mixed effect population pharmacodynamic model used to analyze samples results and define inclusion criteria. In green those that correspond to patients who showed a positive response; in orange those who failed. Conclusions: OPB-111077 is generally well tolerated and has a manageable toxicity profile. The MTD was not reached. The 50% PR rate achieved by OPB-111077, albeit in a few patients, is substantially higher that the 0.7% (1/145) PR rate achieved in a prior phase I trial on all tumor types1. This innovative Phase Ib design selecting patients using a biomarker may enable to rescue drug failures in the future. References: 1. Tolcher A, Flaherty K, Shapiro GI et al. Oncologist. 2018, 23(6):658-e72 Figure Disclosures Martinez-Lopez: Hosea: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; BMS: Research Funding, Speakers Bureau; Amgen: Speakers Bureau; Roche: Speakers Bureau; Janssen: Speakers Bureau; Vivia Biotech: Honoraria; Altum: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Novartis: Research Funding; Takeda: Speakers Bureau; Incyte: Research Funding, Speakers Bureau. Gorrochategui:VIVIA BIOTECH: Current Employment. Rojas:VIVIA BIOTECH, S.L.: Current Employment. Primo:Vivia Biotech: Current Employment. Perez De Oteyza:MACROGENICS: Research Funding. Ballesteros:Vivia Biotech: Current Employment.