Decitabine In Acute Myeloid Leukemia Research Articles

Preferential HDAC6 inhibitors derived from HPOB exhibit synergistic antileukemia activity in combination with decitabine

Histone deacetylase 6 (HDAC6) is an emerging drug target to treat oncological and non-oncological conditions. Since highly selective HDAC6 inhibitors display limited anticancer activity when used as single agent, they usually require combination therapies with other chemotherapeutics. In this work, we synthesized a mini library of analogues of the preferential HDAC6 inhibitor HPOB in only two steps via an Ugi four-component reaction as the key step. Biochemical HDAC inhibition and cell viability assays led to the identification of 1g (highest antileukemic activity) and 2b (highest HDAC6 inhibition) as hit compounds. In subsequent combination screens, both 1g and especially 2b showed synergy with DNA methyltransferase inhibitor decitabine in acute myeloid leukemia (AML). Our findings highlight the potential of combining HDAC6 inhibitors with DNA methyltransferase inhibitors as a strategy to improve AML treatment outcomes.

Preclinical Evaluation of Bisantrene As Single Agent and in Combination with Decitabine for Acute Myeloid Leukemia

Anthracyclines, particularly doxorubicin and idarubicin, together with cytarabine, have comprised standard of care induction chemotherapy in acute myeloid leukemia (AML) for almost 4 decades. Although 60% of patients achieve remission, the majority relapse within 1-2 years. As such, outcomes in AML remain poor, with overall 5-year survival around 27%. In elderly AML patients the situation is worse, with 80% dying within one year of diagnosis. Toxicity of induction therapy is a major barrier to treatment success, precluding many unfit and elderly patients. Hypomethylating agents (HMA; azacytidine, decitabine) provide a less toxic alternative and have improved treatment options for the unfit. However, only 50% of patients respond to HMA therapy and most eventually acquire resistance, resulting in relapse. Approaches that reduce the toxicity of induction therapy and improve the efficacy of HMA treatment are emerging, e.g. combinations with Venetoclax. Nevertheless, novel combination strategies that improve outcomes in certain mutation subtypes need to be explored. Bisantrene, an anthracene derivative developed over 4 decades ago as a less cardiotoxic chemotherapy alternative to anthracyclines, shows broad activity across multiple solid and haematological malignancies. Several clinical studies in the 1980s showed bisantrene is an effective AML salvage therapy, producing response rates up to 50% without accompanying cardiotoxicity (Rothman J., 2017 Int J Cancer Res Ther;2(2):1-10) In a recent investigator-led Phase II trial of heavily pre-treated relapsed/refractory AML patients, 1/10 achieved a complete remission and 3/10 patients achieved partial remission. Interestingly, all responders were characterised by extramedullary disease (Cannani et al., 2020 Eur J Haematol 2021;106:260-266). We postulate that bisantrene may represent a suitable candidate for combination with HMA in patients unfit for standard induction chemotherapy. To explore this idea, we evaluated the in vitro and in vivo effects of bisantrene both alone and in combination with decitabine. The in vitro activity of bisantrene was initially assessed in a range of human and mouse AML cell lines covering the major molecular and clinical subtypes. All cells were sensitive to bisantrene, showing IC 50 values in the range 16-563 nM. FLT3-ITD + cells in particular were sensitive, while NRAS, KRAS and KIT mutant lines were also responsive. When tested against primary patient AML samples, 15/49 (30.6%) responded strongly to bisantrene treatment ex vivo over the dose range 0.1-1 µM. Bisantrene was shown to induce G1 accumulation and dose-dependent apoptosis in the FLT3-ITD + cell line, MOLM13. When tested in combination with decitabine, pre-treatment with decitabine for 24 h followed by decitabine plus bisantrene for 3 days produced synergistic cytotoxicity in MOLM13, MV4-11 and OCI-AML3 cells. Bisantrene and decitabine together resulted in S phase accumulation in MOLM13 cells and synergistic induction of apoptosis. The in vivo efficacy of bisantrene alone and in combination with decitabine were examined using the MOLM13- luc cell line and a patient derived xenograft (PDX; AML16) (FLT3-ITD +, NPM1, IDH2 and WT1 mutant) in NSG mice. Bisantrene (10 mg/kg i.v. twice/week) significantly reduced leukemic burden and increased median survival compared to vehicle control in MOLM-13- luc engrafted mice, and significantly reduced leukemic burden and increased median survival in a dose and schedule-dependent manner (2.5mg/kg and 5mg/kg, twice or three times weekly) in the PDX model. The combination of bisantrene (5 or 10 mg/kg twice weekly) and decitabine (0.2 mg/kg i.p. 5 days/week) significantly improved survival in MOLM13- luc (Figure 1) and PDX AML16 (Figure 2) engrafted mice, respectively, relative to vehicle control and each single agent. The combination also reduced leukemic infiltration to extramedullary sites (spleen, liver, uterus, brain). These data support that addition of bisantrene to HMA backbone therapy may provide an important new treatment strategy in AML. A prospective Phase Ib/II trial is being planned to evaluate this new therapeutic approach.

Preclinical Development of Hosu-53, a Novel Potent Dihydroorotate Dehydrogenase Inhibitor with Impressive Single Agent Efficacy and Combination Approaches in Hematological Malignancy

Common FDA approved strategies for hematological malignancies include chemotherapy, targeted therapies, immune therapies, hypomethylating agents, and cell-based therapeutics. However, recurrence often occurs resulting in poor prognosis particularly in acute myeloid leukemia (AML) with first relapse and multiple myeloma (MM) following several relapses based upon more therapies being available. The emergence of dihydroorotate dehydrogenase as an appealing mechanistic target in AML has propelled the development of several clinical candidate DHODH inhibitors (DHODHi) such as brequinar. Here we describe HOSU-53, a novel DHODHi with favorable oral bioavailability (>50% in mouse, rat, and dog) and a pharmacodynamic (PD) biomarker for target engagement, enabling clinical in vivo monitoring of potency and on-target anti-tumor activity. Here we describe the development of a series of DHODHi through a collaboration between Hendrix College and The Ohio State University (OSU). Our initial screen of 18 novel compounds synthesized at Hendrix College identified HOSU-3 as a potent DHODHi with efficacy equivalent to brequinar, however in vivo efficacy in a MOLM-13 AML xenograft model revealed further optimization would be required to compete with leading clinical candidates. Further structure activity relationship studies and lead optimization performed in collaboration with the Drug Development Institute at OSU led to screening over 200 additional analogs and the development of three additional compounds (HOSU-28, -49 and -53). HOSU-53 has subnanomolar biochemical activity against human DHODH in a cell-free enzyme assay, with a cellular IC50 ranging from 2 - 45 nM across a panel of AML cell lines, and 12-42 nM in MM cell lines. While HOSU-53 is highly plasma protein bound, it exhibits a moderate serum shift in assays using human plasma proteins with an IC50 of 457 nM, well below the in vivo Cmax and AUC achieved in rodent and canine pharmacokinetic (PK) studies (Cmax = 79.4-210 μM and AUC = 997-7961 μM-h). Additional absorption, distribution, metabolic and excretion (ADME) and safety studies revealed that HOSU-53 displays very favorable drug-like properties sufficient for development as a pre-clinical candidate. A MOLM-13 xenograft study verified that HOSU-53 was a potential new best in class DHODHi, with efficacy superior to the Bayer clinical candidate. We performed a follow-up study to determine the efficacy of dosing daily at 4, 10, and 20 mg/kg versus 30 mg/kg twice a week. Correlative PK/PD studies were also conducted to measure plasma HOSU-53 and DHO levels at day 1 and 14. We observed a dose linear relationship between HOSU-53 plasma concentration and DHO accumulation. Collectively, our efficacy and PK/PD studies indicate that 10 mg/kg is a highly efficacious and tolerable daily regimen, while higher doses can be safely administered intermittently, and DHO accumulation serves as an important plasma biomarker to identify in vivo therapeutic responses and toxicity. Confirmatory studies in rat subcutaneous MOLM-13 and MV4-11 xenograft models further demonstrated the efficacy of HOSU-53. Our group has previously described synergy between HOSU-53 and decitabine in AML, as well as monoclonal antibodies directed to CD38 in AML and MM. Furthermore, a novel combination between HOSU-53 and CD47 antibody is described in a separate abstract at this current meeting. We expanded our combination studies by testing HOSU-53 with another standard of care, the FLT3 inhibitor gilteritinib, using the MOLM-13 FLT3-ITD mutant xenograft model. NCG mice were enrolled ten days post engraftment to receive daily 4 mg/kg HOSU-53, 30 mg/kg gilteritinib or the combination. Single agent HOSU-53 and gilteritinib prolonged survival (median survival of 37 and 47 days, respectively) while the combination significantly improved survival with 9/10 mice in the combination group remaining on study at day 80. Collectively, we provide a thorough preclinical assessment for HOSU-53 for treatment in hematological malignancy both as a monotherapy and combined with other effective approved therapies including decitabine, monoclonal antibodies and gilteritinib. We have initiated IND enabling studies including GLP toxicity studies planned for late 2022 and have initiated human dose projection models based on our multi-species PK/PD analysis. We anticipate filing an IND application in 2023 for a phase 1 clinical trial in AML and MM.

Prediction of Clinical Response to Venetoclax Plus Decitabine in AML Using a 7-Day Ex Vivo Assay

Prediction of Clinical Response to Venetoclax Plus Decitabine in AML Using a 7-Day Ex Vivo Assay

Abstract 1049: Optimizing the treatment schedule of selinexor in combination with decitabine in AML

Abstract Background: Decitabine (DEC) is a hypomethylating agent approved to treat acute myeloid leukemia (AML) that can reactivate tumor suppressor genes that are epigenetically silenced by DNA methylation. Selinexor (SEL) is a selective inhibitor of nuclear export that inhibits exportin 1 (XPO1/CRM1) from shuttling cargoes, including tumor suppressor proteins and oncogene mRNAs bound to eIF4e, from the nucleus to the cytoplasm. DEC priming has been previously found to increase the antileukemic effects of SEL in AML in vitro and in vivo, through DEC-mediated upregulation of tumor suppressor proteins such as CDKN1A (p21) and FOXO3A, which are XPO1 cargos localized in the nucleus after SEL treatment. The goal of this study was to determine the optimal dosing schedule for combination treatment of SEL and DEC in AML. Methods: The efficacy of concomitant and sequential drug treatment using DEC and SEL was evaluated in the subcutaneous implanted MV4-11 xenograft models of AML in NOD-SCID mice. Tumor bearing mice were treated with vehicle, SEL once weekly at 15 mg/kg, DEC at 0.4 mg/kg (M-F, week 1 only) and combinations of DEC with SEL 15 mg/kg on Mondays only (DEC + SEL M, concomitant) or Fridays only (DEC + SEL F, sequential) starting from week 1. In the follow up experiment mice were treated similarly except for revised combination group schedules, SEL was administered once weekly starting either from Friday of week 1 (sequential A) or Monday of week 2 (sequential B). Tumor volume and body weight of mice were monitored for five weeks of treatment, and tumors were collected at the end of the study for immunohistochemistry (IHC) analysis. Results: DEC and SEL effectively inhibited tumor growth as single agents. Concomitant administration of SEL and DEC did not enhance the anti-tumor effect, with no significant difference among the tumor growth inhibition (TGI) rate for mice treated with SEL alone (62.7%), DEC alone (60.0%) and the concomitant combination (DEC + SEL M, 62.6%) (p>0.05). Whereas sequential administration of SEL after DEC priming (DEC + SEL F) enhanced the anti-tumor effects, as TGI (81.7%) was significantly higher than each single agent alone (p<0.05). In the follow up experiment, TGI for the two sequential DEC and SEL combination groups was similar (86.19% for sequential schedule A and 86.17% for sequential schedule B, p>0.05). Conclusions: The introduction of SEL post priming with DEC showed greater TGI than when SEL and DEC were dosed concomitantly. A delay of 4-7 days between the first dose of SEL after DEC priming demonstrated better antileukemic effect than concomitant dosing. This is relevant to potential future clinical trials because separation of dosing DEC and SEL has the potential to increase tolerability of the combination without affecting antileukemic activity. Citation Format: Leah F. Henegar, Hua Chang, Christopher J. Walker, Trinayan Kashyap, Nicholas Fredette, Kathleen Martyn, Sharon Shacham, Yosef Landesman. Optimizing the treatment schedule of selinexor in combination with decitabine in AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1049.

Comparative Analysis for Effectiveness of Azacitidine Versus Decitabine in Acute Myeloid Leukemia and Myelodysplastic Syndromes in New Mexico: A Single Institution Experience

IntroductionPrognosis of acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS) is still very poor due to limited treatment options. Both azacitidine (AZA) and decitabine (DEC) have to been shown to have a significant overall survival benefit in MDS patients. In recent years, both drugs are increasingly used for relapsed refractory AML as well as de novo AML in elderly patients with multiple comorbidities. However, we do not have the results of prospective clinical trials comparing AZA directly to DEC in AML or MDS patients. The goal of this study is to evaluate the overall survival and response duration of the AML and MDS patients who received at least one cycle of AZA or DEC in University of New Mexico Comprehensive Cancer Center (UNMCC).MethodsA retrospective chart review was performed to identify clinical characteristics, treatment duration and overall survival in AML and MDS patients. AML patients were risk stratified into favorable, intermediate and poor risk categories based on cytogenetics and molecular abnormalities. MDS patients were also risk stratified into low, intermediate and high-risk categories based on International Prognostic Scoring System. A majority of MDS patients in the study were in intermediate to high-risk categories. The primary patient outcome was overall survival (OS), calculated from the date of diagnosis until the date of death or lost to follow-up. Kaplan-Meier method was applied to compare OS between two groups, azacitidine-treated and decitabine-treated patients.ResultsIn this study, 60 patients (82%) received AZA and 13 patients (18%) received DEC as a treatment for either AML or MDS. Median age at diagnosis for AZA group was 69 years old and DEC group was 62 years old. There were 34 females (57%) in AZA group, compared to 6 females (46%) in DEC group. There were 22 patients with therapy related AML in both groups. DEC group had a higher proportion of patients (8 out of 13, 62%) with relapsed refractory AML, compared to only 25 out of 60 (42%) patients in AZA group with the p value of 0.229. There were 35 De novo AML and MDS patients in AZA group and 5 in DEC group.Median duration of treatment was 3.2 months and median number of treatment cycles was 4 for both groups. There was no significant difference in median overall survival between two groups (AZA 18 months vs DEC 17 months, p=0.082). The median overall survival for relapsed refractory AML in both groups was also similar (AZA 16.6 months versus DEC 18.2 months, p=0.932). However, median overall survival was significantly longer for AZA group with MDS or de novo AML patients (AZA 25 months versus DEC 3 months, p=0.001).ConclusionA significant number of patients with MDS and AML received AZA than DEC in UNMCC and it is similar to the previously reported Surveillance, Epidemiology, and End Results-Medicare database analysis which showed a majority of patients (78%) received AZA. Although we have a limited number of patients in both groups, the median overall survival for de novo AML and MDS patients is significantly higher in AZA group than DEC group. We are awaiting results from the ongoing prospective randomized clinical trials comparing azacitidine versus decitabine in AML and MDS patients to confirm these findings. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Phase I/Ib Trial of the MUC1 Inhibitor GO-203-2C Alone and in Combination with Decitabine for Acute Myeloid Leukemia

MUC1, an oncogenic protein aberrantly expressed on AML and leukemic stem cells, supports critical aspects of the malignant phenotype including resistance to apoptosis, cell proliferation and autonomous self renewal. GO-203-2C is a novel cell-penetrating peptide that blocks homodimerization of the MUC1-C subunit required for nuclear translocation and downstream signaling. In murine AML models, treatment with GO-203-2C resulted in specific eradication of myeloid leukemia. GO-203-2C is synergistic with hypomethylating agents in pre-clinical models of AML. Based on these findings, we are conducting a phase I/Ib study of GO-203-2C alone and in combination with decitabine in patients with AML.Patients with relapsed or refractory (R/R) AML or those with untreated AML who were not candidates for cytotoxic therapy were eligible. Study design consisted of a dose escalation phase with 3 patients each treated with 6.25mg/m2, 12.5mg/m2 and 18mg/m2 intravenous GO-203-2C alone on days 1-5, 8-12 and 15-19 of a 28 day treatment cycle. A subsequent dose escalation with a total of 7 patients was conducted with G0-203-2C at 12.5mg/m2 and 18mg/m2 GO-203-2C administered on day 1-5 and 8-12 in conjunction with decitabine at the standard dose of 20mg/m2 on days 8-12 of each cycle. The study is currently enrolling an expansion cohort; outcomes for 20 patients will be available once the accrual goal is met.Median age was 66 (45 - 81) years with equal gender representation. ECOG performance status was 1 or 2 in all patients. 3 patients were treated upfront and 13 had R/R disease after one to five prior therapies including 4 post-allogeneic transplant. AML prognostic risk was determined according to ELN strata with 12% favorable, 44% intermediate and 44% high risk. Adverse events were primarily CTCAE grade 1 or 2. There was an episode of grade 3 hypertriglyceridemia in one patient and grade 2 pancreatitis in another for which study drug was held and grade 3 hypertension for which dose was reduced. 5 episodes of treatment delay occurred amongst 3 patients due to grade 3-4 neutropenia or thrombocytopenia. Median time to absolute neutrophil >1.0 x 10^9/uL or platelet >100 x 10^9/uL was 8 days with cessation of therapy required in one case that failed to recover by day 50. Another patient experienced atrial fibrillation leading to 4 missed doses of GO-203-2C in cycle 1 and was not evaluable for dose-limiting toxicity but continued on study receiving 9 of 10 doses in cycle 2 and was included in response assessment.Response was defined by IWG criteria as complete remission (CR), complete remission with incomplete count recovery (CRi), or partial remission (PR). Patients in the cohort with GO-203-2c alone received up to 2 cycles of therapy. All 9 patients treated with GO-203-2c alone had resistant disease on marrow assessment but 1 patient had sustained clearance of peripheral blasts. In the combination cohort, response was achieved in 57% (4 of 7). One patient achieved CR and remains on therapy cycle 11. Two patients achieved CRi, although one was taken off study for hematologic toxicity, the other relapsed prior to cycle 3. One patient had partial remission after cycle 2 but later progressed. 1 patient had resistant disease after 3 cycles and two had progressive disease (PD) defined as doubling of peripheral blood blast count or marrow blast percentage, after 1 or 2 cycles. Amongst patients who had response, 2 were upfront and 2 R/R; 2 patients had favorable risk, 1 intermediate and 1 high risk disease.We have previously reported that suppression of the immune response by MUC1 in AML is associated with expansion of myeloid-derived suppressor cells (Pyzer AR. Blood 2017) and up-regulation of PD-L1 expression (Pyzer AR, Leukemia 2017). Of note, response to GO-203-2C treatment was associated with decreased MUC1 expression on CD34+CD38-lineage- leukemia stem cells from 3 evaluable patients. MUC1 inhibition also resulted in decreased PD-L1 expression in leukemia cells and reduction in myeloid derived suppressor cells as demonstrated by multichannel flow cytometric analysis of CD11B+HLA-DR-CD33+ cells.In summary, the results demonstrate that the combination of GO-203-2C and decitabine is safe, and importantly, demonstrates both anti-leukemia and immunomodulatory effects. DisclosuresStone:Ono: Consultancy; Roche: Consultancy; Juno Therapeutics: Consultancy; Jazz,: Consultancy; Novartis: Consultancy; DSMN: Consultancy; Pfizer: Consultancy; Janssen: Consultancy; Cornerstone: Consultancy; Astellas: Consultancy; Amgen: Consultancy; Agios: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sumitomo Dainippon: Consultancy. DeAngelo:Immunogen: Honoraria, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Research Funding; Pfizer Inc.: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Research Funding; BMS: Consultancy; ARIAD: Consultancy, Research Funding; Incyte: Consultancy, Honoraria; Blueprint Medicines: Honoraria, Research Funding; Shire: Honoraria; Glycomimetics: Research Funding; Takeda Pharmaceuticals U.S.A., Inc.: Honoraria; Celgene: Research Funding. Neuberg:Synta Pharmaceuticals: Other: Stock shares. Avigan:Genus Oncology: Research Funding.

Prognostic value of measurable residual disease after venetoclax and decitabine in acute myeloid leukemia

Assessment of measurable residual disease (MRD) provides prognostic information in acute myeloid leukemia (AML). However, the utility of MRD with venetoclax-based lower intensity regimens is unknown. We analyzed the prognostic value of achieving a negative MRD in older/“unfit” patients with AML receiving first-line therapy with 10-day decitabine and venetoclax. MRD was evaluated in bone marrow specimens using multicolor flow cytometry (sensitivity 0.1%). Ninety-seven patients achieving either a complete remission (CR) or CR with incomplete hematologic recovery (CRi) or morphologic leukemia-free state were included. Median age was 72 years (interquartile range, 68-78 years), and 64% had adverse-risk AML. Eighty-three patients achieved CR/CRi, and 52 (54%) became MRD negative. Median time to becoming MRD negative was 2.0 months (interquartile range, 0.9-3.1 months). Patients becoming MRD negative by 2 months had longer relapse-free survival (RFS) compared with those remaining MRD positive (median RFS, not reached vs 5.2 months; hazard ratio [HR], 0.31; 95% confidence interval [CI], 0.12-0.78; P = .004), longer event-free survival (EFS) (median EFS, not reached vs 5.8 months; HR, 0.25; 95% CI, 0.12-0.55; P < .001), as well as longer overall survival (OS) (median OS, 25.1 vs 7.1 months; HR, 0.23; 95% CI, 0.11-0.51; P < .001). Patients achieving an MRD-negative CR had longer OS compared with those with an inferior response (median OS, 25.1 vs 11.6 months; HR, 0.33; 95% CI, 0.19-0.58; P < .0005). Patients becoming MRD negative within 1 month had an improved OS compared with MRD-positive patients (median OS, 25.1 vs 3.4 months; HR, 0.15; 95% CI, 0.03-0.64; P < .0001). Differential impact of MRD status on survival outcomes persisted at a later 4-month time point of evaluation. In conclusion, MRD-negative status at 1, 2, and 4 months after starting therapy confers significantly better survival in older/unfit patients with AML receiving first-line therapy with 10-day decitabine and venetoclax. This trial was registered at www.clinicaltrials.gov as #NCT03404193.

Efficacy of 10-day decitabine in acute myeloid leukemia

The azanucleotide decitabine is used in the treatment of acute myeloid leukemia (AML). Studies have shown conflicting results with 10-day regimens used in previously untreated AML patients. Additionally, there is little data on 10-day decitabine regimens in the relapsed setting. This study investigated outcomes of 108 adult patients with AML in the upfront and relapsed setting treated with a 10-day decitabine regimen. In the upfront group, the overall response rate (ORR, CR + CRi) was 36.1% and the median overall survival (OS) was 6.6 months, while the relapsed/refractory group had an ORR of 25% with an OS of 4.8 months. When analyzed with respect to cytogenetics, the upfront group featured an ORR of 28.1% with an OS of 9.4 months in the intermediate cytogenetic cohort compared to a 40.5% ORR and an OS of 5.4 months in the unfavorable cytogenetic cohort. An analysis of the relapsed/refractory group demonstrated an ORR of 26.3% with an OS of 7.9 months for intermediate cytogenetics versus 25.0% with an OS of 1.8 months in the unfavorable cohort. While these response rates are similar to previously published data, the median OS appears shorter.

Decitabine shows anti-acute myeloid leukemia potential via regulating the miR-212-5p/CCNT2 axis.

Previous research has revealed the involvement of microRNA-212-5p (miR-212-5p) and cyclin T2 (CCNT2) in acute myeloid leukemia (AML). However, whether the miR-212-5p/CCNT2 axis is required for the function of decitabine in AML has not been well elucidated. Quantitative reverse transcription-polymerase chain reaction was used to examine enrichment of miR-212-5p. The relationship between CCNT2 and miR-212-5p was verified by the luciferase reporter assay. Cell apoptosis was evaluated by flow cytometry and western blot. CCK-8 assay was performed to determine cell viability. Decitabine significantly repressed cell viability, while promoted cell apoptosis. Meanwhile, the expression levels of cyclinD1, CDK4, and Bcl-2 were suppressed in cells with decitabine exposure, but Bax and caspase-3 expression levels were upregulated. Besides, miR-212-5p upregulation had the similar function with decitabine in AML cell proliferation and apoptosis. Subsequently, restoration of CCNT2 attenuated miR-212-5p overexpression-induced effects in Kasumi-1 and SKNO-1 cells. In addition, miR-212-5p depletion reversed decitabine-induced CCNT2 downregulation. The miR-212-5p/CCNT2 axis had an implication in the anti-leukemic effect of decitabine in AML.

Prognostic Value of Measurable Residual Disease after Venetoclax and Decitabine in Acute Myeloid Leukemia

Assessment of measurable residual disease (MRD) provides prognostic information in acute myeloid leukemia (AML). However, the utility of MRD with venetoclax-based lower intensity regimens is unknown. We analyzed the prognostic value of achieving a negative MRD in older/"unfit" patients with AML receiving first-line therapy with 10-day decitabine and venetoclax. MRD was evaluated in bone marrow specimens using multicolor flow cytometry (sensitivity 0.1%). Ninety-seven patients achieving either a complete remission (CR) or CR with incomplete hematologic recovery (CRi) or morphologic leukemia-free state were included. Median age was 72 years (interquartile range, 68-78 years), and 64% had adverse-risk AML. Eighty-three patients achieved CR/CRi, and 52 (54%) became MRD negative. Median time to becoming MRD negative was 2.0 months (interquartile range, 0.9-3.1 months). Patients becoming MRD negative by 2 months had longer relapse-free survival (RFS) compared with those remaining MRD positive (median RFS, not reached vs 5.2 months; hazard ratio [HR], 0.31; 95% confidence interval [CI], 0.12-0.78; P = .004), longer event-free survival (EFS) (median EFS, not reached vs 5.8 months; HR, 0.25; 95% CI, 0.12-0.55; P < .001), as well as longer overall survival (OS) (median OS, 25.1 vs 7.1 months; HR, 0.23; 95% CI, 0.11-0.51; P < .001). Patients achieving an MRD-negative CR had longer OS compared with those with an inferior response (median OS, 25.1 vs 11.6 months; HR, 0.33; 95% CI, 0.19-0.58; P < .0005). Patients becoming MRD negative within 1 month had an improved OS compared with MRD-positive patients (median OS, 25.1 vs 3.4 months; HR, 0.15; 95% CI, 0.03-0.64; P < .0001). Differential impact of MRD status on survival outcomes persisted at a later 4-month time point of evaluation. In conclusion, MRD-negative status at 1, 2, and 4 months after starting therapy confers significantly better survival in older/unfit patients with AML receiving first-line therapy with 10-day decitabine and venetoclax. This trial was registered at www.clinicaltrials.gov as #NCT03404193.

Abstract A43: Plasma-derived circulating tumor DNA (ctDNA) as a surrogate biomarker for treatment response with the polo-like kinase 1 (PLK1) inhibitor, onvansertib, in combination with LDAC or decitabine in acute myeloid leukemia (AML)

Abstract Background: Cancer cells from solid tumors release ctDNA into the bloodstream, clinically enabling assessment, monitoring tumor mutational heterogeneity, treatment response, minimal residual disease (MRD), and disease progression. However, the clinical utility of ctDNA in AML has yet to be established. In AML, blast cells carrying a driver mutation originate in the bone marrow (BM) and migrate into circulation in peripheral blood (PB). Here, we aimed to determine the potential of ctDNA as a surrogate for response to treatment in the phase 1b/2 study (NCT03303339) testing the efficacy and safety of the PLK1 inhibitor, onvansertib, in combination with either decitabine or LDAC in relapsed or refractory AML (R/R AML). Methods: R/R AML patients were dosed for 5 days with onvansertib in combination with either decitabine (5 days) or LDAC (10 days) within 21 to 28-day cycle. BM aspirates and blood samples were collected pre-dose, at the end of cycles 1, 2 and every other cycle after. Genomic DNA (gDNA) was extracted from BM and PB mononuclear cells (BMMCs and PBMCs, respectively), while ctDNA was extracted from plasma. Clinically significant mutations were detected in gDNA from PBMCs and BMMCs using a next-generation sequencing panel targeting variants in 75 genes associated with AML. For each patient, a droplet digital PCR (ddPCR) assay was developed to assess mutant allele frequencies (MAF) of a single variant of interest across timepoints and three sample sources (BMMC, PBMC, and Plasma). MAF changes across all 3 sample sources were compared to the clinical response assessed by immunohistochemistry in bone marrow aspirate (BM-IHC). Results: As of October 16th, 16 patients were evaluated, totaling 33 timepoints with MAF measured in all 3 sources. MAF in plasma highly correlated with BMMCs MAF (R2 = 0.85), more so than PBMCs with BMMCs (R2 = 0.78) and over plasma with PBMCs (R2 = 0.68). Clinically, 4 patients had a complete response (with or without count recovery, CR+CRi) and showed a corresponding drop in ctDNA MAF at or before clinical diagnosis. Similarly, 3 of 4 evaluable patients with progressive disease showed an increase in ctDNA MAF before or at the timepoint when blast percentages rose in BM, with the fourth patient maintaining a stable MAF across timepoints. In 5 patients with stable disease, 2 showed a divergence between ctDNA MAF and BM-IHC, while 3 maintained congruency. Conclusions: Serial testing of plasma-derived ctDNA was representative of treatment response and relapse in R/R AML patients. The correlation between ctDNA MAF and BMMCs MAF supports the utility of ctDNA as a surrogate biomarker for disease status, and in some cases provides a more immediate diagnostic of response or nonresponse. More patients need to be evaluated to build an objective classification of clinical significance around ctDNA MAF, and, importantly, the biology of R/R AML subclonal heterogeneity and MRD likely necessitate interrogation and monitoring of multiple variants of interest. Citation Format: Errin Samuelsz, Maya Ridinger, Mark Erlander, Latifa Hassaine, Marion Luebbermann, Brittany Ross. Plasma-derived circulating tumor DNA (ctDNA) as a surrogate biomarker for treatment response with the polo-like kinase 1 (PLK1) inhibitor, onvansertib, in combination with LDAC or decitabine in acute myeloid leukemia (AML) [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A43.

Phase I study of AR-42 and decitabine in acute myeloid leukemia

This phase I trial sought to determine a biologically safe and effective dose of AR-42, a novel histone deacetylase inhibitor, which would lead to a doubling of miR-29b prior to decitabine administration. Thirteen patients with previously untreated or relapsed/refractory AML were treated at 3 dose levels (DL): AR-42 20 mg qd on d1,3,5 in DL1, 40 mg qd on d1,3,5 in DL2 and 40 mg qd on d1,3,4,5 in DL3. Patients received decitabine 20 mg/m2 on d6–15 of each induction cycle and 20 mg/m2 on d6–10 of each maintenance cycle. One DLT of polymicrobial sepsis and multi-organ failure occurred at DL3. Two patients achieved a CRi and one patient achieved a CR for an ORR of 23.1%. The higher risk features of this patient population and the dosing schedule of AR-42 may have led to the observed clinical response and failure to meet the biologic endpoint.

Comparative Analysis for Effectiveness of Azacitidine Versus Decitabine in Acute Myeloid Leukemia and Myelodysplastic Syndromes with Marrow Fibrosis: A Single Institution Experience

Comparative Analysis for Effectiveness of Azacitidine versus Decitabine in Acute Myeloid Leukemia and Myelodysplastic Syndromes with Marrow Fibrosis: A Single Institution Experience Ala Ebaid, MD1, Shashank Cingam, MD1, Quiying Liu, MD2, Khine Z Win3, MD, Daniel Babu, MD4, Tawny Boyce, MS, MPH4, Cecilia Arana-Yi, MD1 Department of Internal Medicine, Hematology/Oncology, University of New Mexico, Albuquerque, NM. Department of Internal Medicine, University of New Mexico, Albuquerque, NM. University of California San Francisco. University of New Mexico and Tricore Reference Laboratories Department of Internal Medicine, Division of Epidemiology, Biostatistics and Preventive Medicine, University of New Mexico, Albuquerque, NM. Introduction The hypomethylating agents (HMA) azacitidine (AZA) and decitabine (DEC) are used clinically for the management of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML); however, treatment responses and survival outcomes are very limited. Bone marrow fibrosis (MF) is present in 10-20% of MDS/AML and is predictor of poor responses to azacitidine and dismal survival outcomes. Genetic abnormalities including TP53 accumulation, WT1 gene expression, increased CXCL9 and CXCL10 among others contribute to the etiology of MF. The impact of MF in therapeutic responses and survival to AZA versus DEC has not been previously assessed. Methods Retrospective chart review of cases from 2000-2019 at UNM Cancer Center to identify clinical characteristics, cytogenetic, molecular status, treatment and overall survival. AML patients were risk stratified according to ELN risk category, and MDS patients based on their IPSS-R scoring system. 142 bone marrow samples were analyzed for marrow fibrosis with hematoxylin and eosin-stained slides and confirmed with trichrome staining at Tricore Reference lab. 92 AML patients had a complete cytogenetics analysis. The goal of this study is to evaluate the clinical, pathologic characteristics and survival outcomes of AML and MDS patients with and without MF treated with AZA compared to DEC at the University of New Mexico Comprehensive Cancer Center. Results 142 patients with MDS (n=45, 31.7%) and AML (n=97, 68.3%) treated with AZA (n=85) 59.9%, and DEC (n=57) 40.1%. 45 patients have MF (31.7%) vs. 97 patients without MF (68.3%). 39.4% (n=56) were females, 31.7% had MDS (n=45), 68.3% had AML (n=97) and 31.7% (n=45) had MF. The median age at diagnosis was 69.5 years for the AZA group and 68 years for the DEC group. In AML group there was 20 (20.8%) patients with high-risk cytogenetics and 38 (39.6%) with diploid cytogenetics. There was no statistical difference between the MF degree and the cytogenetics of the patients. In the MDS group 9 patients (20%) with very low risk IPSS, 16 (35.6%) low risk, 13 (28.9%) intermediate and 13 (15.5%) patients with high and very high risk IPSS. In the fibrosis group 21 patients (46.7%) had low grade and 24 patients (53.3%) had high grade (MF2 and MF3). There were no significant differences in MF degree and IPSS or ELN categories. Median duration of treatment was 3.2 months and median number of treatment cycles was 4 for AZA and 3 for DEC. There was no significant difference in median overall survival between two groups (AZA 18 months vs DEC 17 months, p=0.3355). Median overall survival was not significant in AZA group with de novo AML patients (AZA 19 months versus DEC 15 months, p=0.3013). There were no OS differences in AML and MDS patients with MF. (Figure 1) Patients with MF on AZA had a trend toward better OS compared to DEC. (Figure 2) In MDS and AML, younger than 65 years old had better OS compared to older than 65 years. (p=0.011) In AML, TP53 mutation was associated with worsening survival outcomes. (median OS 2m vs 18m, p=0.0238) Conclusions The frequency of MF was 46.7% in MDS and 24.7 % of AML cases, higher than reported in other studies. However, MF did not affect survival outcomes of MDS/AML treated with AZA or DEC. Although non-statistically significant, MF cases had a trend towards better survival on AZA compared to DEC. The presence of TP53 was associated with decreased survival in AML patients with fibrosis. Our study confirms that MF is a common feature in MDS/AML in New Mexico, but does not influence survival outcomes in patients treated with AZA or DEC. Disclosures Arana Yi: Jazz Pharmaceuticals: Other: Advisory Board.

Maintenance Decitabine (DAC) Improves Disease-Free (DFS) and Overall Survival (OS) after Intensive Therapy for Acute Myeloid Leukemia (AML) in Older Adults, Particularly in FLT3-ITD-Negative Patients: ECOG-ACRIN (E-A) E2906 Randomized Study

Maintenance Decitabine (DAC) Improves Disease-Free (DFS) and Overall Survival (OS) after Intensive Therapy for Acute Myeloid Leukemia (AML) in Older Adults, Particularly in FLT3-ITD-Negative Patients: ECOG-ACRIN (E-A) E2906 Randomized Study

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

TP53 and Decitabine in Acute Myeloid Leukemia and Myelodysplastic Syndromes

BackgroundThe molecular determinants of clinical responses to decitabine therapy in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) are unclear.MethodsWe enrolled 84 adult patients with AML or MDS in a single-institution trial of decitabine to identify somatic mutations and their relationships to clinical responses. Decitabine was administered at a dose of 20 mg per square meter of body-surface area per day for 10 consecutive days in monthly cycles. We performed enhanced exome or gene-panel sequencing in 67 of these patients and serial sequencing at multiple time points to evaluate patterns of mutation clearance in 54 patients. An extension cohort included 32 additional patients who received decitabine in different protocols.ResultsOf the 116 patients, 53 (46%) had bone marrow blast clearance (<5% blasts). Response rates were higher among patients with an unfavorable-risk cytogenetic profile than among patients with an intermediate-risk or favorable-risk cytogenetic profile (29 of 43 patients [67%] vs. 24 of 71 patients [34%], P<0.001) and among patients with TP53 mutations than among patients with wild-type TP53 (21 of 21 [100%] vs. 32 of 78 [41%], P<0.001). Previous studies have consistently shown that patients with an unfavorable-risk cytogenetic profile and TP53 mutations who receive conventional chemotherapy have poor outcomes. However, in this study of 10-day courses of decitabine, neither of these risk factors was associated with a lower rate of overall survival than the rate of survival among study patients with intermediate-risk cytogenetic profiles.ConclusionsPatients with AML and MDS who had cytogenetic abnormalities associated with unfavorable risk, TP53 mutations, or both had favorable clinical responses and robust (but incomplete) mutation clearance after receiving serial 10-day courses of decitabine. Although these responses were not durable, they resulted in rates of overall survival that were similar to those among patients with AML who had an intermediate-risk cytogenetic profile and who also received serial 10-day courses of decitabine. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT01687400.)

Diverticulitis in the Neutropenic Patient: Case Report and Literature Review

Diverticulitis is a common gastrointestinal disease, however, it is rarely described in patients with immunosuppression. Neutropenic patients with fever and abdominal symptoms such as pain, diarrhea and rectal bleeding are considered to have C difficile colitis or typhlitis. However a third possibility is diverticulitis which can lead to perforation and sepsis. Acute diverticulitis in the setting of neutropenia is rarely reported in literature. An 82 year old male presented with a 1 month history of abdominal pain accompanied by fevers, anorexia, emesis, and constipation. He was previously treated with decitabine for acute myeloid leukemia leading to a 4 month history of neutropenia with an absolute neutrophil count less than 100x103/μL. He reported a prior history of diverticulosis and a single episode of prior diverticulitis managed conservatively with oral antibiotics one year ago. He denied use of nonsteroidal anti-inflammatory drugs, tobacco or alcohol. On admission, blood cultures were negative and a CT of the abdomen and pelvis revealed severe sigmoid diverticulitis. The patient was started on piperacillin/tazobactam which was transitioned to ciprofloxacin and metronidazole after 8 days of therapy. He developed worsening abdominal pain and repeat imaging revealed progression of sigmoid diverticulitis without evidence of abscess; therapy was escalated to piperacillin/tazobactam. Fluconazole prophylaxis was begun and clostridium difficile testing was negative. A repeat CT scan 19 days after admission revealed perforation of the sigmoid with several fluid collections concerning for abscess formation. Surgery recommended against operative intervention or CT guided drainage due to pancytopenia. Antibiotics were transitioned to meropenem and metronidazole. His condition continued to deteriorate and he was discharged home with hospice and no antibiotics.Figure 1Figure 2Figure 3Typically, patients improve when their neutropenia resolves. This case exemplifies a rare occurrence of diverticulitis in a patient with prolonged neutropenia. It illustrates the complications associated with this disease including abscess formation and perforation. Unfortunately, this patient's severe disease precluded him from any aggressive surgical intervention and conservative therapy failed. This disease pattern necessitates provider familiarity for optimal therapy, the role of surgical drainage, and patient outcomes in the setting of prolonged neutropenia and thrombocytopenia.

North American Leukemia, Intergroup Phase III Randomized Trial of Single Agent Clofarabine As Induction and Post-Remission Therapy, and Decitabine As Maintenance Therapy in Newly-Diagnosed Acute Myeloid Leukemia in Older Adults (Age ≥60 Years): A Trial of the ECOG-ACRIN Cancer Research Group (E2906)

▪Background: Induction therapy with daunorubicin (Dauno) & cytarabine (Ara-C) [DA] has been the standard of care for eligible older adults (age ≥ 60 years) with newly diagnosed acute myeloid leukemia (AML) for over 2 decades. Single agent Clofarabine (CLO) induction & consolidation (Consol.) therapy has demonstrated important clinical activity in this age group in large phase II studies. Lower induction mortality (IM) & similar reported complete remission rate (CR) & overall survival (OS), as well as notable activity in those with higher risk disease features [including unfavorable cytogenetics, therapy-related AML (t-AML) & prior antecedent hematologic disorder (AHD)] raises the possibility that a non-Ara-C-based regimen could achieve similar or superior OS with lower toxicity.Methods: We performed a randomized United States Intergroup Phase III trial of single agent CLO [30mg/m2 x 5 days induction; 20 mg/m2 re-induction (if indicated) & 2 cycles Consol.] vs. standard DA therapy [Dauno 60mg/m2 D1-3 & Ara-C 100mg/m2 D1-7 induction x 1-2 cycles; 2 cycles Consol. with Ara-C (1.5g/m2 Q12hrs D1-6 age 60-69; once daily if age 70+)] in patients (pts) age ≥ 60 yrs with newly diagnosed AML. Patients with serum creatinine >1.0 (or GFR <60 mL/min) and those with AML-M3 and ECOG performance status >3 (PS>2 if age 70+ yrs) were excluded. Randomization was stratified by age (60-69 vs. 70+), t-AML, & AHD. Pts with HLA-matched donor were eligible for allogeneic transplantation (AlloHCT) after induction, and those completing Consol. were eligible for randomization #2 (R#2) to maintenance decitabine [20mg/m2 x 3D, monthly x 1 year] versus observation. With a target accrual of 747, E2906 was powered to determine non-inferiority [and possible superiority] of CLO vs. standard DA, and primary endpoint was OS. A weighted statistical analysis was performed to account for confounding impact of R#2. AlloHCT patients were censored at transplant in this analysis. Responses & cytogenetics were confirmed centrally and OS & CR rates were monitored by an independent Data Safety Monitoring Committee (DSMC) at pre-specified time points.Results: As of Feb 23, 2015, 727 pts were randomized. Median age was 68 years (range 60-86); 57% were male, and 38% were age ≥70 yrs. Treatment arms are well balanced for all baselineclinical & AML characteristics, & 30% had unfavorable cytogenetics. Of 659 with complete treatment information reported, 30.4% on DA vs. 40.1% on CLO received 2 cycles of induction (p=0.006).Median follow-up of surviving patients is 7.6 months.Table 1shows early treatment results (CR, toxicity) for the 686 pts randomized as of Dec 23, 2014 (2 months prior to study end, & excluding 90 with ongoing response evaluation).DACLOp-valueCR/CRi43.8%42.8%p=0.8730-day mortality8.5%7.9%p=0.8960-day mortality14.9%13.1%p=0.58Gr 4-5 Non-Heme Tox.Induction27%19%p=0.02Gr 4-5 Non-Heme Tox.Consol.20%7%p=0.001374 pts have died (174, DA; 200, CLO) & significantly inferior OS was observed for CLO vs. DA [Hazard Ratio (HR) 1.41 (95% CI 1.12-1.78)] (Fig. 1). Planned subgroup analyses were performed (Table 2) demonstrating significant differences in OS after CLO for patients age 60-69 yrs, without AHD, & with intermediate risk cytogenetics; but not for those with Unfav. Cytogen. (Fig. 2) or t-AML. Based on the primary weighted analysis, DSMC recommended suspension of new accrual to E2906 on Feb 23, 2015 & all active patients on CLO were transitioned to DA Arm. Table 2NHR CLO/Standard (95% CI)*Weighted OS7271.41 (1.12-1.78)Unweighted OS7271.23 (1.00-1.50)Age 60-694491.48 (1.10-1.99)Age 70+2781.34 (0.93-1.93)Intermed. Risk Cytogen.3781.77 (1.27-2.47)Unfav. Risk Cytogen.2160.96 (0.65-1.43)No AHD6041.46 (1.13-1.89)AHD1231.22 (0.74-2.00)De novo AML6271.52 (1.18-1.96)Therapy-related AML1000.94 (0.54-1.61)Conclusions: Despite similar CR & IM, OS after single agent CLO is inferior to standard DA therapy for pts age ≥60 years with newly diagnosed AML who are fit for intensive therapy, and DA remains the standard of care. However no difference in OS was observed after CLO in some pre-specified high risk AML subgroups. R#2 & AlloHCT arms continue in E2906 for pts already enrolled. Embedded prospective minimal residual disease study at CR is being performed to identify pts at higher risk after CLO & DA. [Display omitted] [Display omitted] DisclosuresOff Label Use: Use of clofarabine in AML, and maintenance therapy with decitabine in AML. Claxton:Medimmune: Research Funding; BMS: Consultancy; Astellas: Research Funding; Cyclacel: Research Funding; Merck: Research Funding; Ambit: Research Funding. Levine:Loxo Oncology: Membership on an entity's Board of Directors or advisory committees; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees; Foundation Medicine: Consultancy. Altman:Seattle Genetics: Consultancy; BMS: Consultancy; Spectrum: Consultancy; Astellas: Consultancy; Ariad: Consultancy; Novartis: Consultancy. Al-Kali:Novartis: Research Funding.

Endpoints of Clinical Trials for Marketing Authorization of Drugs for Hematologic Malignancy in Japan, the US and the EU

Background: Pharmaceuticals and Medical Devices Agency (PMDA) in Japan, the US Food and Drug Administration (FDA) in the US and the European Medicines Agency (EMA) in the EU review drug applications for market approval. It was shown that most new molecular entity (NME) agents were first approved in the US because the FDA has reviewed applications more quickly (N Engl J Med. 2012; 366: 2284-93). However, differences in regulatory actions among Japan, the US and the EU in terms of relationship between the approval date and primary endpoints of pivotal trials in marketing applications including supplemental applications for additional indications have never been analyzed comprehensively. Methods: 93 indications of 55 hematologic anticancer drugs approved in Japan, the US or the EU (only central marketing authorization by the European Commission) between August 2000 and June 2014 were examined in this research. Information concerning regulatory decisions made by PMDA, the FDA and the EMA was obtained from publicly accessible data only such as PMDA’s review reports, the PMDA website, the FDA’s review reports, the Drugs@FDA website, the European public assessment reports published by the EMA’s Committee for Medicinal Products for Human Use (CHMP) and the EMA website. Results: 24, 60, and 9 indications were first approved in Japan, the US, and the EU, respectively. 2 NME agents were first approved in Japan and the EU each; mogamulizumab for relapsed CCR4-positive adult T-cell leukemia/lymphoma as well as relapsed CCR4-positive peripheral T-cell lymphoma/cutaneous T-cell lymphoma and tamibarotene for relapsed acute promyelocytic leukemia in Japan and pixantrone dimaleate for relapsed aggressive non-Hodgkin B-cell lymphoma and histamine dihydrochloride for acute myeloid leukemia in the EU. 17 indications were approved only in the US and 13 of these were approved based on response rate in single-arm trials. The other 4 indications were approved based on results of comparative trials. Of the 13 indications approved based on single-arm trials, 8 indications were approved through the accelerated approval scheme in the US. 5 indications (pixantrone dimaleate, histamine dihydrochloride, temsirolimus for relapsed mantle cell lymphoma, rituximab as maintenance therapy for relapsed follicular lymphoma and decitabine for acute myeloid leukemia) were approved only in the EU and 4 other indications (ibritumomab tiuxetan as consolidation therapy for follicular lymphoma and rituximab for diffuse large B-cell lymphoma, newly diagnosed chronic lymphocytic leukemia, and relapsed chronic lymphocytic leukemia) were approved the earliest in the EU. All these 9 indications were approved based on results of comparative trials. Of these 9 indications, only pixantrone dimaleate was approved through the conditional approval scheme and only histamine dihydrochloride was approved through the approval under exceptional circumstances scheme. Although 23 indications were approved only in Japan, most of them were additional indications of old drugs and not based on results of comparative trials. Primary endpoints were different between the US and the EU in 3 of 41 indications approved in both the US and the EU. All these 3 indications were approved earlier in the US and response rate or time to progression (TTP) in the US instead of progression-free survival (PFS) or overall survival (OS) in the EU was adopted as the primary endpoints as follows; thalidomide for newly diagnosed multiple myeloma (TTP in the US and OS in the EU), pomalidomide for relapsed multiple myeloma (overall response rate in the US and PFS in the EU), and azacitidine for myelodysplastic syndrome (complete remission rate in the US and OS in the EU). Conclusions: The conditional approval scheme or the approval under exceptional circumstances scheme in the EU and the accelerated approval scheme in the US are available, while there are no similar schemes for oncologic drugs in Japan. However, this analysis suggests that the FDA has taken a more active attitude to acceptance of surrogate endpoints. Therefore, not only shorter review time but also this attitude may lead to earlier marketing authorization of drugs for hematologic malignancy in the US. Disclosures Off Label Use: I will discuss off-label drug use in the US which has been approved in the EU or Japan..