Dynamic assessment of measurable residual disease in favorable-risk acute myeloid leukemia in first remission, treatment, and outcomes

We aimed to investigate outcomes of different post-remission treatment (PRT) choices based on dynamic measurable residual disease (MRD) by multiparameter flow cytometry in favorable-risk AML (FR-AML). Four hundred and three younger patients with FR-AML in first complete remission (CR1) were enrolled in this registry-based cohort study, including 173 who received chemotherapy (CMT), 92 autologous stem cell transplantation (auto-SCT), and 138 allogeneic SCT (allo-SCT). The primary endpoint was the 5-year overall survival (OS). Subgroup analyses were performed based on dynamic MRD after the 1st, 2nd, and 3rd courses of chemotherapy. In subgroups of patients with negative MRD after 1 or 2 course of chemotherapy, comparable OS was observed among the CMT, auto-SCT, and allo-SCT groups (p = 0.340; p = 0.627, respectively). But CMT and auto-SCT had better graft-versus-host-disease-free, relapse-free survival (GRFS) than allo-SCT in both subgroups. For patients with negative MRD after three courses of chemotherapy, allo-SCT had better disease-free-survival than CMT (p = 0.009). However, OS was comparable among the three groups (p = 0.656). For patients with persistently positive MRD after 3 courses of chemotherapy or recurrent MRD, allo-SCT had better OS than CMT and auto-SCT (p = 0.011; p = 0.029, respectively). Dynamic MRD might improve therapy stratification and optimize PRT selection for FR-AML in CR1.

TP53 and KRAS Variants at Initial Diagnosis Identify an Ultra-High Risk Group of Pediatric T-Lymphoblastic Leukemia (T-ALL)

Introduction Patients who suffer a relapse of pediatric T-cell acute lymphoblastic leukemia (T-ALL) face a dismal prognosis. Prognostic molecular biomarkers that reliably predict the risk of relapse at the time of first diagnosis are not available. Inactivating mutations in TP53 were previously detected in approximately 10% of relapsed patients (Hof et al. J Clin Oncol. 2011) and are invariably associated with fatal outcome (Richter-Pechanska et al. Blood Cancer J. 2017). Mutations in other genes were identified to be either specific for relapse (NT5C2 and CCDC88A) or to be associated with a poor prognosis in relapse (IL7R, KRAS, NRAS, USP7, CNOT3 and MSH6) (Meyer et al. Nat Genet. 2013; Richter-Pechanska et al. Blood Cancer J. 2017). We hypothesized that subclones bearing such mutations can give rise to relapse and analyzed these 9 genes at initial diagnosis of T-ALL with targeted ultra-deep sequencing. Methods Leukemia samples collected at initial diagnosis of 81 children with T-ALL who later relapsed were analyzed. As a control group, we selected 79 children with T-ALL who remained in first remission for at least three years and were matched with regard to treatment response, treatment, age and sex. Targeted deep sequencing was performed by using the Agilent Haloplex High Sensitivity kit with unique molecular identifiers for reliable detection of mutations with very low allele frequencies (average read depth: 1,012x). Results Overall, we detected 75 mutations among 7 targeted genes in 33 / 81 relapsing and 21 / 79 non-relapsing patients. The average allele frequency (AF) of the identified mutations was 25% (0.8% - 83%; SD ± 18%). More than half of the variants (43/75) showed AFs below 30% and were thus classified as subclonal. Interestingly, 7 pathogenic TP53 mutations (subclonal: n=5, clonal: n=2) with AFs of 4.4% - 49.4% were exclusively discovered in 6 patients who experienced a relapse. While 2 of these patients received an allogeneic stem cell transplantation in first remission because of poor treatment response, the remaining 4 patients were treated by chemotherapy in the high-risk (n=1) or medium-risk (n=3) arm. None of the 79 non-relapsing control patients carried TP53 mutations. Consistent with the hypothesis of clonal evolution as a mechanism of relapse in T-ALL, Sanger Sequencing of the relapse sample of one TP53-positive patient confirmed that the subclone harboring the TP53 mutation A159D at initial diagnosis (AF 5.4%) expanded to a major clone (AF 42%) in relapse. The presence of TP53 mutations in two further TP53-positive patients in at least one available post-remission sample is also compatible with clonal selection. However, in a fourth patient the low allele frequency of the TP53 mutation at relapse indicates that the TP53 subclone persisted but did not expand during the development of relapse. In addition to TP53, we identified pathogenic KRAS mutations to be significantly enriched in relapsing patients (9 / 81) compared to non-relapsing patients (2 / 79) at the time of initial diagnosis (chi-squared test, p= 0.032; Table 1). Conclusion Subclonal and clonal mutations in TP53 and KRAS at initial diagnosis were enriched in T-ALL patients who later relapsed and identified approximately 17% of patients suffering a relapse. We thus propose that (subclonal) mutations of TP53 and KRAS may define a subgroup of high-risk T-ALL patients already at the time of first diagnosis. The identification of such mutations may complement the current risk stratification which depends on treatment response and may determine a new molecularly defined subgroup of T-ALLs that may benefit from intensified treatment strategies. Figure 1 Figure 1. Disclosures Schrappe: SigmaTau: Other: research support; Amgen: Other: research support; Servier: Honoraria; Novartis: Honoraria; JazzPharma: Honoraria; Servier: Honoraria, Other: research support; JazzPharma: Honoraria, Other: research support; SHIRE: Other: research support; Novartis: Honoraria, Other: research support. Cario: Novartis: Other: Lecture Fee. Muckenthaler: Silence Therapeutics: Research Funding. Kulozik: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BioMedX: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; bluebird bio, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria.

Replacing the Anthracycline By Gemtuzumab Ozogamicin in Older Patients with De Novo Standard-Risk Acute Myeloid Leukemia Treated Intensively - Results of the Randomized ALFA1401-Mylofrance 4 Study

Introduction Based on the results of the ALFA-0701 trial (Castaigne et al. Lancet 2012), the addition of fractionated doses of the anti-CD33 antibody drug conjugate gemtuzumab ozogamicin (GO, Mylotarg®) to conventional chemotherapy has been approved in 2017 for frontline treatment of adults with CD33-positive acute myeloid leukemia (AML). Prolonged event-free survival (EFS) was observed in patients with AML of favorable or intermediate risk, while not in those with adverse cytogenetics. Nevertheless, more frequent added toxicities could make the addition of GO a questionable option in patients over 60-65 years of age. In this ALFA-1401/Mylofrance 4 trial (NCT02473146), we investigated if the replacement of the anthracycline by GO might also improve EFS in older patients. Methods Between January 2016 and March 2019, 225 patients were randomized 2:1 to receive an experimental GO-cytarabine combination (154 patients) or a standard anthracycline-cytarabine treatment (71 patients). Patients aged 65 to 80 years old (later extended to patients aged 60-64 years old), with previously untreated de novo AML of favorable or intermediate cytogenetics were eligible for the trial. Standard treatment arm consisted in a 7+3 using idarubicin at 12 mg/m 2/d on day 1 to 3 and cytarabine 200 mg/m 2/d on day 1 to 7. Experimental arm (GO arm) consisted of two doses of GO 3 mg/m 2/d on day 1 and 4 and cytarabine 200 mg/m 2/d on day 1 to 7. Post-remission therapy comprised two courses of intermediate-dose cytarabine (IDAC) at 1.5 g/m 2/12h on day 1, 3 and 5. In the GO arm, a third dose of 3mg/m 2/d GO was administered on day 1 of the first IDAC course. The first IDAC course could serve as second induction in patients not responding to the first one. The decision to perform allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first remission was left to the discretion of the physician. The efficacy analysis was conducted in the modified intent-to-treat (mITT) population excluding patients who did not meet the cytogenetic eligibility criteria. The primary study endpoint was EFS. Secondary endpoints were response rate defined by complete remission (CR), CR with incomplete platelets recovery (CRp) and CR with incomplete hematological recovery (CRi), early mortality, relapse incidence, overall survival (OS) and safety. Results Among the 225 randomized patients, 214 (71 standard arm, 143 GO arm) were included in the mITT population. There were 126 men and 88 women. Median age was 70 years (61-80). Cytogenetics was of favorable and intermediate risk in 14 and 200 patients, respectively. One hundred and eighty-one patients reached CR/CRp/CRi, 64 (90%) in standard arm and 117 (82%) in GO arm (p=0.17). Median follow-up time was 38 months. At 2 years, estimated EFS was 38% [95% CI, 28-51] in the standard arm vs. 29% [22-37] in the GO arm (Hazard Ratio (HR), 1.37 [0.98-1.93]; p= 0.067) (Figure 1A). Overall, 118 patients relapsed, 36 (51%) in standard arm and 82 (57%) in GO arm. At 2 years, estimated cumulative incidence of relapse was 48% [36-61] in standard arm vs. 61% [52-70] in GO arm (csHR, 1.32 [0.90-1.93]; p= 0.078). Overall, 122 patients died, 38 (54%) in standard arm, 84 (59%) in GO arm. Sixty-day mortality was 4% in standard arm vs. 10% in GO arm (p=0.13). At 2 years, estimated OS was 65% [55-77] in standard arm vs. 52% [45-61] in GO arm (HR, 1.27 [0.86-1.87]; p= 0.23). In subgroup analysis for EFS (Figure 1B), we found a significant interaction with gender, GO having a detrimental effect in women which persisted after adjustment on known prognostic factors. A total of 33 patients received allo-HSCT in first remission, 19 (30%) in standard arm and 14 (12%) in GO arm (p=0.006). When censoring these patients at transplant time, HR of GO on EFS was 1.27 ([0.88-1.83]; p=0.19). Regarding safety, 76% and 80% of patients had at least one grade 3 to 5 adverse event (p=0.81), including infection in 30% vs. 21% and bleeding in 7% vs. 29% in standard arm and GO arm respectively. Serious adverse events were reported in 34% of patients in standard arm vs. 49% in GO arm (p=0.031). Sinusoidal obstruction syndrome occurred in 2 patients in the GO arm. Conclusion Frontline use of GO instead of idarubicin, when combined to cytarabine, does not benefit older patients with de novo standard-risk AML. At the reduced dose schedule used in this study, GO remains associated with significant toxicities while non-significant higher relapse incidence, shorter EFS and shorter OS were observed. Figure 1 Figure 1. Disclosures Lambert: ASTELLAS: Consultancy; CELGENE/BMS: Consultancy. Pautas: ABBVIE: Consultancy; PFIZER: Consultancy. Gastaud: PFIZER: Consultancy; CELGENE/BMS: Consultancy; ABBVIE: Consultancy; GSK: Consultancy. Barbieux: ASTRA-ZENECCA: Consultancy. Rousselot: Incyte, Pfizer: Consultancy, Research Funding. Castaigne: PFIZER: Consultancy. Dombret: Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Honoraria, Research Funding; Servier: Research Funding; Abbvie: Honoraria; Daiichi Sankyo: Honoraria; BMS-Celgene: Honoraria.

Dynamic Assessment of Measurable Residual Disease in Favorable-Risk Acute Myeloid Leukemia in First Remission, Treatment, and Outcomes

Purpose:We aimed to investigate outcomes of different post-remission treatment (PRT) choices based on dynamic measurable residual disease (MRD) in favorable-risk AML (FR-AML). Methods: Four hundred and three younger patients with FR-AML in first complete remission (CR1) were enrolled in this registry-based cohort study, including 173 who received chemotherapy (CMT), 92 autologous stem cell transplantation (auto-SCT), and 138 allogeneic SCT (allo-SCT). Subgroup analyses were performed based on dynamic MRD after the first, second, and third courses of chemotherapy. The primary endpoint was the 5-year overall survival (OS). Results: For patients with negative MRD after 1 course of chemotherapy, comparable OS was observed among the CMT, auto-SCT and allo-SCT groups (p=.284). But CMT had better graft-versus-host-disease-free, relapse-free survival (GRFS) than allo-SCT (p=.027). For patients with negative MRD after 2 courses of chemotherapy, comparable OS was also observed among the three groups (p=.967). However, CMT and auto-SCT had better GRFS than allo-SCT (p=.045; p=.020, respectively). For patients with negative MRD after 3 courses of chemotherapy, allo-SCT had better disease-free-survival than CMT (p=.011). However, OS was comparable among the three groups (p=.177). For patients with persistently positive MRD after 3 courses of chemotherapy or recurrent MRD, allo-SCT had better OS than CMT and auto-SCT (p=.012; p=.046, respectively). Conclusions: Dynamic MRD might improve therapy stratification and optimize PRT selection for FR-AML in CR1. CMT might be preferable for patients with negative MRD within 3 cycles of chemotherapy while allo-SCT for patients with persistently positive MRD after 3 cycles of chemotherapy and recurrent MRD. Disclosures No relevant conflicts of interest to declare.

Intensified Cytarabine Dose during Consolidation Therapy in AML Patients Under 65 Years Is Not Associated with Survival Benefit

Background: Acute myeloid leukemia (AML) is characterized by a high relapse rate, indicating insufficient clearance of leukemia-initiating cells. Depending on genetic risk stratification, consolidating chemotherapy proves to significantly reduce the risk of relapse. In particular, in younger AML patients higher dosage of cytarabine appears to improve long-term outcome, while there is no apparent benefit of multiagent combination, compared to cytarabine monotherapy. However, to this end the optimal dosage of single agent cytarabine in consolidation therapy after 7+3 remission induction remains elusive. Methods: Here, we retrospectively assessed the impact of different dosages of cytarabine consolidation on outcome in a large real-world data set from the German Study Alliance Leukemia-Acute Myeloid Leukemia (SAL-AML) registry. Patients below 65 years of age, registered between April 2005 and September 2020 with non-acute promyelocytic leukemia, who attained complete remission after intensive induction and received at least one consolidation cycle with intermediate (IDAC) or high dose cytarabine (HiDAC) were selected. To account for differences in patient and disease characteristics between both groups, the average treatment effect was estimated by propensity score weighting. Results: 642 patients received HiDAC consolidation with a median dosage of 5794.88 (IQR, 4745.48-5971.56) mg/m 2/d with a median number of 3 cycles (IQR, 2-3), whereas 178 patients received IDAC consolidation with 1946.16 (IQR, 1869.51-2469.15) mg/m 2/d with a median of 2 cycles (IQR, 1-3). IDAC-treated patients showed in average a higher age (median (IQR) 58.5 (49-62) years vs. 50 (41-56) years) and more comorbidities with 43.8% having an HCT-CI score of 2-4, compared to 22.3% among HiDAC-treated patients. Alongside, significantly more secondary (5.1% vs. 3.1%) and therapy-related (12.4% vs. 4.1%) AML as well as more adverse (14.5% vs. 6.5%) and less favorable (40.6% vs. 56%) genetic risk features according to ELN 2017 risk classification were found among IDAC-treated patients. After propensity score weighting for differences in patient and disease characteristics, overall survival after 5 years was comparable between HiDAC-treated (71.1 %) and IDAC-treated (67.7%) patients. Moreover, no significant differences in relapse-free survival were observed after 5 years (47.4 vs. 45.2%). Notably, more patients treated with IDAC received allogeneic stem cell transplantation in first remission (37.6 vs. 19.8%) while significantly more HiDAC-treated patients underwent allogeneic stem cell transplantation in relapse (30.8 vs. 20.2%). Censoring for allogeneic stem cell transplantation in first remission revealed no significant survival difference with regard to cytarabine dosage. Considering only ELN favorable risk AML patients, there was no difference in 5-years overall (80.5% vs. 83.9%) nor relapse-free (57.7% vs. 56.8%) survival. Of note, significantly more patients treated with HiDAC suffered from ≥3 CTCAE infectious complications (56.7 vs. 44.1%), which was more striking in patients above 50 years of age. The rate of other ≥3 CTCAE non-hematological toxicities and secondary malignancies was comparable in both treatment groups. Conclusion: This retrospective analysis suggests no significant benefit of high dose cytarabine compared to intermediate dosages in consolidation for AML patients under 65 years of age, independent of ELN risk group. Disclosures Krause: Siemens: Research Funding; Takeda: Honoraria; Pfizer: Honoraria; art-tempi: Honoraria; Kosmas: Honoraria; Gilead: Other: travel support; Abbvie: Other: travel support. Schliemann: Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; BMS: Consultancy, Other: travel grants; Jazz Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy. Haenel: Jazz: Consultancy, Honoraria; GSK: Consultancy; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Brummendorf: Takepart Media: Honoraria; Repeat Diagnostics: Research Funding; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Patents & Royalties, Research Funding; Janssen: Honoraria; Bristol Myers: Research Funding. Fransecky: Abbvie: Honoraria, Research Funding; Medac: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Takeda: Honoraria. Einsele: Janssen, Celgene/BMS, Amgen, GSK, Sanofi: Consultancy, Honoraria, Research Funding. Held: MSD: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Roche: Research Funding; Acortech Biopharma: Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Platzbecker: Janssen: Honoraria; Celgene/BMS: Honoraria; AbbVie: Honoraria; Geron: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Baldus: Amgen: Honoraria; Celgene/BMS: Honoraria; Novartis: Honoraria; Jazz: Honoraria. Mueller-Tidow: Janssen Cilag: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Bioline: Consultancy, Research Funding.

Outcomes Are Similar Following Allogeneic Hematopoietic Stem Cell Transplant for Newly Diagnosed Patients Who Received Venetoclax + Azacitidine Versus Intensive Chemotherapy

Background: Venetoclax-based therapy regimens are now FDA-approved for treatment of acute myeloid leukemia (AML) in older patients or those unfit to tolerate intensive chemotherapy (IC). Remission rates are high at 60-70% but relapses do frequently occur. Outcomes for newly-diagnosed patients who receive venetoclax-based therapies and proceed to a potentially curative allogeneic stem cell transplant (SCT) have largely been unreported. In the current study we compare outcomes of patients who received SCT following either IC or venetoclax + azacitidine (ven/aza) at the University of Colorado Hospital. Methods: Patients 18 years or older who received SCT in first remission of AML between 2010-2020 were included in the analysis. Patients were stratified into the IC arm if they initially received a backbone of cytarabine and an anthracycline; some patients in this cohort received IC in combination with other targeted agents. Patients who received ven/aza as first-line therapy followed by SCT were grouped in a separate cohort. Demographic and clinical information - including flow cytometry-based (MCF) MRD - was extracted from the electronic medical record. Comparisons of demographic and clinical variables between IC and ven/aza groups were made with t-test, Chi-squared, or Fisher's exact test depending on the nature of the variable. Relapse-free (RFS) and overall (OS) survival were calculated from the day of SCT to the respective endpoint or last documented follow-up using log-rank statistics. Finally, a Cox proportional hazards model was used to assess the interplay between variables pre- and post-SCT. P-values <0.05 were considered significant. Results: We identified 179 patients who received SCT for AML in first remission. Of these patients, 151 received IC and 28 received ven/aza prior to SCT. Patients in the ven/aza group had higher median age than those in the IC group, as well as a higher proportion with adverse ELN genetic risk scoring. Patients in the ven/aza group received less intensive conditioning regimens. Sex, rates of MCF MRD negativity pre-BMT, incidence of severe acute or chronic GVHD, and causes of death were not significantly different between the two groups. There was no difference between the two groups in post-transplant RFS or OS (Figure 1). In a multivariate Cox model of pre-transplant variables predicting OS, the only factor that achieved significance was pre-SCT MCF MRD; the induction regimen was not a multivariate factor. Negative MCF MRD going into SCT was associated with decreased likelihood of relapse, GVHD, and death, respectively. Conclusions: In our cohort of AML patients receiving SCT, we found that ven/aza as a pre-transplant therapy yielded equivalent post-transplant outcomes compared to IC, in a population of older age and with higher ELN genetic risk. MCF MRD pre-SCT was confirmed as a key prognostic factor for post-SCT outcome. These findings support ongoing use of ven/aza as a first line therapy for elderly patients with AML as well as its exploration as a candidate therapy for younger patients. Figure 1 Figure 1. Disclosures Pollyea: Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other; Aprea: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kiadis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Syndax: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Agios: Other, Research Funding; Karyopharm: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Teva: Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Curis, Servier: Other; Pfizer: Research Funding; Syros: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Other: advisory board; Foghorn: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Other: advisory board; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: advisory board.

Allogeneic Hematopoietic Cell Transplantation in Patients ≤ 60 Years with Intermediate-Risk Acute Myeloid Leukemia in First Remission - Results of the Randomized Etal-1 Trial-

Allogeneic hematopoietic cell transplantation (HCT) offers the highest chance for cure in patients with adverse-risk acute myeloid leukemia (AML) when performed in first remission (CR1). In contrast, patients in CR1 with favorable risk do not seem to benefit from allogeneic HCT due to the inherent risk of transplant-related mortality. Donor vs. no donor comparisons as well as prospective matched-pair analyses have suggested that allogeneic HCT performed in intermediate-risk AML may provide a higher probability of overall survival or relapse-free survival in patients ≤ 60 years of age with an acceptable risk for transplant-related mortality. On the other hand, many intermediate-risk patients relapsing after conventional chemotherapy may be successfully salvaged by allogeneic HCT. The role of allogeneic HCT in cytogenetically defined intermediate-risk AML patients in CR1 was addressed by a prospective randomized trial performed in 16 centers in Germany. Key inclusion criteria were: AML with intermediate-risk cytogenetics, first CR or CRi after conventional induction therapy, age of 18-60 years, and availability of an HLA-matched sibling or unrelated donor. For unrelated donors, a 9 out of 10 HLA allelic match was acceptable except for patients with an NPM1 mutation, for whom full 10/10 allele matching was required. Randomization was stratified according to age (< 40 vs. 40-60), NPM1/FLT3, and CEBP-alpha mutational status and unrelated vs. related donor availability. Endpoints included overall-survival as primary outcome and relapse-free survival (RFS), cumulative incidence of relapse, treatment-related mortality, and quality of life measured according to the short form (36) health status. From 2010 - 2018, 143 patients in CR1 were randomized into Arm A (n=76, allogeneic HCT) and Arm B (n=67, conventional consolidation and allo-HCT only in case of relapse). In July 2018, the trial was stopped prematurely due to slow accrual (143 out of 356 pts. randomized). Median age of the trial cohort was 51 years (range, 19-60), with 42% exhibiting an NPM1 and 25% a FLT3 mutation. A normal karyotype was reported in 84% of the included patients. All mentioned characteristics did not differ between both treatment arms. Sibling donors were available for 44 (31% of patients), matched unrelated donors for 99 (69%) patients. According to the intent-to-treat analysis, the probability of survival at 2 years was 71% (95% CI 60-81%) and 84% (95% CI 73-92%) in Arm A (Transplant) and Arm B (conventional consolidation), respectively (p=0.120, Figure 1A). RFS after allogeneic HCT was 69% (95% CI 57-80%) compared to 41% (95% CI 29-54%) after conventional consolidation (p=0.001, Figure 1B). Primary allogeneic HCT reduced the cumulative incidence of relapse at 2 years from 57% [95%-CI 46-71%] after conventional consolidation to 20% [95%-CI 13-31%] after HCT (p<0.001). Non-relapse mortality at 2 years after primary allogeneic HCT was 9% [95%-CI 5-19%] compared to 2% [95%-CI 0-11%] after consolidation (p=0.017).Most importantly, all 38 patients relapsing in arm B (33 hematologic, 4 molecular and 1 extramedullary) proceeded to allogeneic HCT as salvage therapy. Multivariable Cox regression analysis revealed a status of CRi compared to CR before randomization to be associated with a significantly higher risk of death (HR 3.3, p=0.009). SF (36) scoring suggested a trend towards a lower physical functioning throughout the first 3 months after randomization in the primary HCT arm. No significant differences in vitality, mental health, social and emotional functioning could be documented between both treatment arms. In summary, the results of this first prospective randomized trial did not show that allogeneic HCT performed immediately after achievement of CR1 in patients with cytogenetically defined intermediate-risk AML ≤ 60 years of age conveys an overall survival advantage. However, allogeneic HCT in CR1 significantly reduced the relapse risk and was not associated with relevant impairments in quality of life. Although the limited statistical power of the trial does not allow definitive conclusions, delayed allogeneic transplantation seems to be a potential treatment algorithm in CR1 intermediate-risk AML with an available donor. Figure 1 Figure 1. Disclosures Schliemann: Jazz Pharmaceuticals: Consultancy, Research Funding; Roche: Consultancy; Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; AstraZeneca: Consultancy; Boehringer-Ingelheim: Research Funding; Novartis: Consultancy; Abbvie: Consultancy, Other: travel grants; Astellas: Consultancy; BMS: Consultancy, Other: travel grants. Schetelig: Roche: Honoraria, Other: lecture fees; Novartis: Honoraria, Other: lecture fees; BMS: Honoraria, Other: lecture fees; Abbvie: Honoraria, Other: lecture fees; AstraZeneca: Honoraria, Other: lecture fees; Gilead: Honoraria, Other: lecture fees; Janssen: Honoraria, Other: lecture fees . Glass: Riemser: Research Funding; Roche: Consultancy, Research Funding, Speakers Bureau; Kite: Consultancy; BMS: Consultancy; Novartis: Consultancy; Helios Klinik Berlin-Buch: Current Employment. Platzbecker: Janssen: Honoraria; Celgene/BMS: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Geron: Honoraria; AbbVie: Honoraria. Burchert: Novartis: Honoraria, Research Funding; AOP Orphan: Honoraria, Research Funding; Pfizer: Honoraria; Incyte: Honoraria; Gilead: Honoraria; BMS: Honoraria. Haenel: Jazz: Consultancy, Honoraria; GSK: Consultancy; Bayer Vital: Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy; Celgene: Consultancy, Honoraria. Mueller: Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; CTI: Membership on an entity's Board of Directors or advisory committees; Gentium: Other: Travel Support; Gilead: Other: Travel Support; Janssen: Other: Travel Support; Novartis: Other: Travel Support; Pfizer: Other: Travel Support; Sanofi: Other: Travel Support. Berdel: Philogen S.p.A.: Consultancy, Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees. Stelljes: Novartis: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau; Celgene/BMS: Consultancy, Speakers Bureau; Medac: Speakers Bureau; Amgen: Consultancy, Speakers Bureau.

Matching Adjusted Indirect Comparison (MAIC) of Oral Azacitidine (Oral-AZA) Versus Injectable AZA in Patients (pts) with Acute Myeloid Leukemia (AML) in First Remission after Intensive Induction Chemotherapy

INTRODUCTION: Oral-AZA was approved in the United States in September 2020 for continued treatment (Tx) of adult patients (pts) with AML in first remission after intensive chemotherapy (IC). The phase 3 QUAZAR AML-001 trial showed that Oral-AZA significantly improved overall and relapse-free survival (OS/RFS) vs placebo (PBO) and was generally well-tolerated (Wei, NEJM 2020). In the phase 3 HOVON97 trial, subcutaneous (SC) AZA maintenance Tx significantly improved disease-free survival vs observation, but did not show an OS benefit (Huls, Blood 2019). Although Oral-AZA and SC AZA contain the same active drug, they are not bioequivalent. Oral administration allows extended exposure to lower drug concentrations, which could increase the number of diseased progenitor cells exposed to AZA and maximize therapeutic effects (eg, drug incorporation into RNA leading to apoptosis), and may improve tolerability by decreasing AZA-related exacerbations of existing cytopenias. In the absence of head-to-head trials, a matching adjusted indirect comparison (MAIC), which adjusts for potential Tx effect modifiers, was previously conducted to evaluate the relative OS benefit with Oral-AZA vs SC AZA (Chen, EHA 2021). This MAIC was performed to determine the relative safety profile and health care resource utilization (HCRU) with Oral-AZA vs SC AZA maintenance therapy in pts with AML in first remission after IC. METHODS: Anchored MAIC analyses of serious Tx-emergent adverse events (SAEs) and HCRU were performed using individual pt data (IPD) from QUAZAR AML-001 to match to baseline (BL) summary statistics from HOVON97. IPD from QUAZAR AML-001 were removed when a pt did not meet HOVON97 eligibility criteria. Remaining QUAZAR AML-001 pt data were weighted using a method-of-moments propensity score model. Matched and adjusted variables were BL age, platelet count, neutrophil count, ECOG performance score, cytogenetic risk, and response status. Analysis endpoints were times to first SAE, hospitalization, and platelet or red blood cell (RBC) transfusion. In HOVON97, pts could receive SC AZA for up to 12 cycles; therefore, QUAZAR AML-001 outcomes were limited to the first 12 cycles of Tx. Hospitalizations for SC AZA administration only in HOVON97 were excluded from analyses. Endpoints are adjusted for pt-years of drug exposure and compared between studies by calculating relative risks (RR). Exposure to SC AZA in HOVON97 was imputed based on the number of pts entering each Tx cycle, and relies on the assumption that events/censoring happened at the end of the cycle and led to Tx discontinuation. Sensitivity analyses of model robustness relaxed these assumptions, comparing only the difference in cumulative hazard vs PBO/observation using a cloglog link binomial model. RESULTS: IPD for 398/469 pts (85%) in the QUAZAR AML-001 safety population (Oral-AZA n=203, PBO n=195) met the eligibility criteria of the HOVON97 population and were adjusted to the comparator. For all endpoints, rate ratios for Oral-AZA vs PBO were less than those for SC AZA vs observation (Table). MAIC-weighted safety comparisons showed the risk of SAEs was reduced by 65% for patients treated with Oral-AZA vs SC AZA (RR 0.35 [95% CI: 0.18-0.68]). Similarly, the risks of hospitalization requirements, platelet transfusion, and RBC transfusion were reduced with Oral-AZA vs SC AZA by 59% (RR 0.41 [95% CI: 0.24-0.71), 54% (RR 0.46 [0.23-0.93]), and 47% (RR 0.53 [0.28-1.00]), respectively. All findings were robust to the sensitivity analyses relaxing assumptions of imputed Tx exposure in HOVON97, which showed pts treated with Oral-AZA are 70% less likely to experience SAEs than pts treated with SC AZA (hazard ratio: 0.30 [95% CI: 0.09-1.02]), and hazard reductions for hospitalization and transfusions ranged from -51% to -58% (Table). CONCLUSIONS : These data suggest that in controlled clinical trials with pts in first remission after IC, Oral-AZA maintenance therapy not only significantly improves OS, but also provides a better safety profile and requires less HCRU than SC AZA maintenance therapy. Interpretation of results should be limited to the differences in the rate to first SAE while on Tx, as stronger generalizations are limited by competing risks and informative censoring. Figure 1 Figure 1. Disclosures Chen: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Huls: Universaity Medical Center Groningen: Current Employment. Cameron: Bristol Myers Squibb: Consultancy. Suero: Bristol Myers Squibb: Consultancy. Vasconcelos: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Gaugler: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Beach: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company.