Supplemental Figure 1 and Figure 2 Supplemental Tables 1-5

Despite the substantial clinical activity of fms-related tyrosine kinase 3 (FLT3) inhibitors in relapsed or refractory (R/R) FLT3-ITD-positive acute myelogenous leukemia (AML), durable remissions and prolonged survival in this population require allogeneic hematopoietic stem cell transplantation (allo-HSCT). Quizartinib, a once-daily oral, highly potent, and selective FLT3 inhibitor, significantly prolonged overall survival (OS) and improved clinical benefit compared with salvage chemotherapy (median OS, 6.2 months versus 4.7 months; hazard ratio [HR], .76; 95% confidence interval [CI], .58 to .98; P = .018; composite complete remission [CRc] rate, 48% versus 27%; median duration of CRc, 2.8 months versus 1.2 months; mortality rate, .8% versus 14% by day 30, 7% versus 24% by day 60) in patients with R/R FLT3-ITD AML in the phase 3 QuANTUM-R trial. In this post hoc analysis, we described the characteristics of and clinical outcomes in patients who underwent on-study HSCT in QuANTUM-R at the investigator's discretion and institutional practices. Of 367 randomized patients, 78 (32%) in the quizartinib arm and 14 (11%) in the salvage chemotherapy arm underwent on-study allo-HSCT without any intervening therapy for AML after quizartinib or study-specified salvage chemotherapy. Pooled data of patients from both treatment arms showed a longer median overall survival (OS) in transplant recipients versus those treated without allo-HSCT (12.2 months versus 4.4 months; HR, .315; 95% CI, .233 to .427). Pooled data also showed a longer median OS in patients with a last recorded response of CRc before allo-HSCT versus patients without a CRc (20.1 months versus 8.8 months; HR, .506; 95% CI, .296 to .864). By treatment arm, the median OS was 25.1 months with quizartinib and 20.1 months with salvage chemotherapy in patients with a last recorded response of CRc before allo-HSCT. Forty-eight patients in the quizartinib arm continued quizartinib treatment after allo-HSCT. In the 31 patients with a last recorded response of CRc before allo-HSCT who continued quizartinib after allo-HSCT, the median OS was 27.1 months. Continuation of quizartinib after allo-HSCT was tolerable, and no new safety signals were identified. These results suggest that post-transplantation survival following salvage chemotherapy and quizartinib treatment are similar. However, quizartinib response occurs more frequently than with salvage chemotherapy, potentially allowing more patients to undergo transplantation and achieve durable clinical benefit. In addition, post-transplant quizartinib was found to be tolerable and may be associated with prolonged survival in some patients, highlighting its potential value in the management of patients with FLT3-ITD R/R AML. (C) 2020 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Quizartinib is an oral, highly potent, and selective type II FMS-like tyrosine kinase 3 inhibitor in development for acute myeloid leukemia. This parallel-group study evaluated potential food effects on quizartinib absorption in healthy subjects who received a single 30-mg dose after overnight fasting (n = 34) or a high-fat, high-calorie meal (n = 30). Blood samples were collected through 504 hours after dosing, and pharmacokinetic parameters calculated were maximum observed concentration (Cmax ) and area under plasma concentration-time curve from time 0 to last quantifiable concentration (AUClast ) and from time 0 to infinity (AUCinf ). Mean quizartinib pharmacokinetic profiles were similar under fasted and fed conditions. The geometric least squares means ratios (%) for fed/fasted and associated 90% confidence intervals (CIs) for Cmax , AUClast , and AUCinf were 91.58 (82.15-102.08), 105.39 (90.79-122.35), and 108.39 (91.54-128.34), respectively. The 90%CI for the ratio fell within the 80% to 125% limits for Cmax and AUClast , with 90%CI for AUCinf slightly outside the limits (ie, 128%). Food delayed quizartinib time to Cmax by 2 hours. All adverse events were either mild or moderate; no discontinuations due to adverse events occurred. Based on these results, quizartinib can be administered without regard to food.

Introduction: In the phase 3 QuANTUM-R trial, once-daily, oral, highly potent and selective FLT3 inhibitor Q improved clinical benefits vs SC (median overall survival [mOS], 6.2 vs 4.7 mo [HR, 0.76 (95% CI, 0.58-0.98); P = .02]; composite complete remission [CRc], 48% vs 27%; median duration of CRc, 12.1 vs 5.0 wk) in 367 pts with R/R FLT3-ITD AML (Cortes et al. Lancet Oncol, 2019; NCT02039726). Prior to randomization, 25% (Q) and 23% (SC) of pts had 1 prior HSCT. An OS sensitivity analysis, with censoring at the time of any subsequent HSCT during QuANTUM-R, was supportive (mOS, 5.7 vs 4.6 mo [HR, 0.79 (95% CI, 0.59-1.05)]; P = .05). Post hoc analyses of characteristics and clinical outcomes in pts who underwent subsequent HSCT in QuANTUM-R are reported. Methods: Pts aged ≥ 18 y with FLT3-ITD R/R AML receiving Q (60 mg [30-mg lead-in]) or 1 of 3 prespecified high- or low-intensity SC regimens and underwent subsequent HSCT as part of the open-label, randomized QuANTUM-R trial were analyzed. Pts receiving HSCT in the Q arm could resume maintenance Q 30-100 days after HSCT. Decisions to proceed to HSCT and resume Q after HSCT were made per investigator discretion/institutional policies. Results: Of 367 randomized pts, 85 in the Q arm underwent any subsequent HSCT (allogenic HSCT [allo-HSCT], 84 [6 with and 78 w/o additional AML therapy]; autologous HSCT, 1) and 19 in the SC arm underwent any HSCT (5 with and 14 w/o additional AML therapy]). Median age (range) was lower in pts with any HSCT (Q, 49 [19-71] y; SC, 44 [23-67] y) vs pts w/o (Q, 58 [19-81] y; SC, 59 [18-78] y). Q + SC pooled data showed a longer mOS (95% CI) in 104 pts with any HSCT vs 263 w/o (12.2 [10.0-24.1] vs 4.4 [4.1-4.9] mo; P < .0001; Fig 1); 1-year OS probabilities (95% CI) were 50% (40%-60%) vs 13% (9%-18%). Among pts preselected for high-intensity therapy (Q [n = 188] + SC [n = 93]), mOS in the pooled high-intensity group was 11.9 (10.0-24.0) mo with any HSCT vs 4.6 (4.1-5.4) mo w/o. Among pts preselected for low-intensity therapy, 13/57 in the Q arm and 0/29 in the SC arm underwent any HSCT; mOS in the pooled low-intensity group was 32.4 (6.2-NA) mo with any HSCT vs 4.1 (2.7-4.6) mo w/o. In pts with CRc (last recorded response prior to allo-HSCT), mean time (range) to allo-HSCT was 13.3 (5.9-26.9) wk with Q and 12.1 (6.3-28.6) wk with SC. Q + SC pooled data showed that mOS (95% CI) was longer in pts with a CRc prior to allo-HSCT vs pts w/o CRc (20.1 [11.7-NA] vs 8.8 [7.0-11.4] mo). Survival outcomes by treatment were similar regardless of study treatment, with longer mOS in pts with any HSCT vs pts w/o (Q, 11.9 [10.2-25.1] vs 4.5 [4.1-5.4] mo; SC, 12.7 [6.1-NA] vs 4.0 [2.7-5.0] mo); respective 1-year OS probabilities (95% CI) were 50% (39%-60%) vs 13% (8%-20%) and 51% (26%-70%) vs 12% (6%-21%). In the Q arm, mOS (95% CI) was longer in pts with a best response of CRc who resumed Q after allo-HSCT (27.1 [18.2-NA] mo) vs pts not resuming Q (5.4 [4.7-11.4] mo; Fig 2). In 48 pts (62%) in the Q arm resuming Q after allo-HSCT, median time (range) from allo-HSCT to Q resumption was 65 (30-106) d. Four pts (5%) in the Q arm died < 30 days after allo-HSCT. As of 2/22/2018, 46 of 78 pts in the Q arm (59%) and 9 of 14 pts in the SC arm (64%) with allo-HSCT w/o additional AML therapy died, primarily due to AML disease progression (Q, 31 [40%]; SC, 7 [50%]). The frequency of treatment-emergent adverse events (TEAEs) was mostly lower in pts resuming Q after allo-HSCT than in the overall Q population (Table 1); TEAEs of interest were similar. Long-term survivor data will be presented. Conclusions: Independent of HSCT, Q improved survival vs SC in pts with FLT3-ITD R/R AML in QuANTUM-R. Q + SC pooled analyses showed longer survival in pts with HSCT vs pts w/o and in pts with CRc prior to allo-HSCT. Importantly, survival post-HSCT was similar in the Q and SC arms, indicating that pts eligible for HSCT were appropriately transplanted, and the higher HSCT rate in the Q arm was beneficial to pts. More pts treated with Q underwent HSCT, likely due to a higher rate and duration of CRc with Q vs SC and better overall fitness. In pts preselected for low-intensity SC at study entry, 13 were able to undergo HSCT after Q treatment. Resumption of Q after HSCT was associated with better survival outcomes and was tolerable. These data illustrate the value of using Q to target the FLT3-ITD mutation as a part of the overall treatment sequence in pts with FLT3-ITD R/R AML. Disclosures Ganguly: Seattle Genetics: Speakers Bureau; Janssen: Honoraria, Other: Advisory Board; Kite Pharma: Honoraria, Other: Advisory Board; Daiichi Sankyo: Research Funding. Cortes:Bristol-Myers Squibb: Consultancy, Research Funding; BiolineRx: Consultancy; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Astellas Pharma: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Sun Pharma: Research Funding; Immunogen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Forma Therapeutics: Consultancy, Honoraria, Research Funding; Biopath Holdings: Consultancy, Honoraria; Merus: Consultancy, Honoraria, Research Funding. Krämer:Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Bayer: Research Funding. Levis:Amgen: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Daiichi Sankyo Inc: Consultancy, Honoraria; Astellas: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Menarini: Consultancy, Honoraria; FUJIFILM: Consultancy, Research Funding. Martinelli:Daiichi Sankyo: Consultancy, Honoraria; Pfizer: Consultancy, Other: trial grant; Celgene: Consultancy, Honoraria, Other: trial grant; Janssen: Consultancy, Other: trial grant; Incyte: Consultancy, Other: trial grant; Amgen: Consultancy, Other: trial grant; Abbvie: Consultancy, Honoraria, Other: trial grant; Novartis: Consultancy, Other: trial grant; Roche: Consultancy, Other: trial grant; Ariad: Consultancy, Other: trial grant. Perl:Novartis: Honoraria, Other: Advisory board, Non-financial support included travel costs for advisory board meetings as well as a medical writing company that assisted with manuscript preparation/submission and slide deck assembly for academic meeting presentations of the data., Research Funding; Bayer: Research Funding; BioMed Valley Discoveries: Research Funding; FujiFilm: Research Funding; Takeda: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Astellas: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings as well as a medical writing company that assisted with manuscript preparation/submission and slide deck assembly for academic meeting presentations of trial data., Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Other, Research Funding; Arog: Consultancy, Other: Non-financial support included travel costs for advisory board meetings.; AbbVie: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Actinium Pharmaceuticals: Consultancy, Honoraria, Other: Clinical Advisory Board member, Research Funding; Agios: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Non-financial support included travel costs for advisory board meetings.; Jazz: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; NewLink Genetics: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.. Russell:Astellas: Consultancy, Honoraria, Speakers Bureau; Pfizer Inc: Consultancy, Honoraria, Speakers Bureau; Jazz: Consultancy, Honoraria, Speakers Bureau; DSI: Consultancy, Honoraria, Speakers Bureau. Arunachalam:Daiichi Sankyo: Employment. Gammon:Daiichi Sankyo: Consultancy. Lesegretain:Daiichi-Sankyo Inc.: Employment, Equity Ownership. Mires:Daiichi Sankyo: Employment. Namuyinga:Daiichi Sankyo: Employment. Zhang:Daiichi Sankyo: Employment. Khaled:Omeros: Consultancy; Daiichi Sankyo: Other: Travel support; Alexion: Consultancy, Speakers Bureau.

AimsQuizartinib is an oral, highly potent and selective next‐generation FMS‐like tyrosine kinase 3 (FLT3) inhibitor under investigation in patients with FLT3‐internal tandem duplication‐mutated acute myeloid leukaemia. This drug–drug interaction study assessed the pharmacokinetics (PK) of quizartinib when coadministered with strong or moderate cytochrome P450 3A (CYP3A) inhibitors.MethodsIn this parallel‐group study, subjects were randomised to receive: (i) quizartinib + ketoconazole; (ii) quizartinib + fluconazole; or (iii) quizartinib alone. On Days 1–28, subjects received ketoconazole 200 mg or fluconazole 200 mg twice daily, and on Day 8, all subjects received a single 30‐mg quizartinib dose. Blood samples were collected for PK analyses, steady‐state PK parameters were simulated by superpositioning, and safety was assessed.ResultsNinety‐three healthy subjects were randomised; 86 completed the study. When administered with ketoconazole, geometric mean ratios (90% confidence interval) for quizartinib maximum observed plasma concentration (Cmax) and area under the plasma concentration–time curve (AUC) from time 0 extrapolated to infinity were 117% (105%, 130%) and 194% (169%, 223%), respectively, vs quizartinib alone. Steady‐state PK simulation demonstrated ~2‐fold increase of both steady–state Cmax and AUC from time 0 to the end of the dosing interval when quizartinib was administered with ketoconazole due to accumulation of quizartinib at steady state. When administered with fluconazole, geometric mean ratios (90% confidence interval) for quizartinib Cmax and AUC from time 0 extrapolated to infinity were 111% (100%, 124%) and 120% (104%, 138%), respectively, vs quizartinib alone. Overall, 5.4% of subjects experienced quizartinib‐related adverse events; no serious adverse events or deaths occurred.ConclusionsThese results suggest reducing the dose of quizartinib when coadministered with a strong CYP3A inhibitor, but not with a moderate or weak CYP3A inhibitor. This dose reduction was implemented in phase 3 evaluation of quizartinib.

Background Old age and FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations in patients with acute myeloid leukaemia are associated with early relapse and poor survival. Quizartinib is an oral, highly potent, and selective next-generation FLT3 inhibitor with clinical antileukaemic activity in relapsed or refractory acute myeloid leukaemia. We aimed to assess the efficacy and safety of single-agent quizartinib in patients with relapsed or refractory acute myeloid leukaemia. Methods We did an open-label, multicentre, single-arm, phase 2 trial at 76 hospitals and cancer centres in the USA, Europe, and Canada. We enrolled patients with morphologically documented primary acute myeloid leukaemia or acute myeloid leukaemia secondary to myelodysplastic syndromes and an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 into two predefined, independent cohorts: patients who were aged 60 years or older with relapsed or refractory acute myeloid leukaemia within 1 year after first-line therapy (cohort 1), and those who were 18 years or older with relapsed or refractory disease following salvage chemotherapy or haemopoietic stem cell transplantation (cohort 2). Patients with an FLT3-ITD allelic frequency of more than 10% were considered as FLT3-ITD positive, whereas all other patients were considered as FLT3-ITD negative. Patients received quizartinib once daily as an oral solution; the initial 17 patients received 200 mg per day but the QTcF interval was prolonged for more than 60 ms above baseline in some of these patients. Subsequently, doses were amended for all patients to 135 mg per day for men and 90 mg per day for women. The co-primary endpoints were the proportion of patients who achieved a composite complete remission (defined as complete remission+complete remission with incomplete platelet recovery+complete remission with incomplete haematological recovery) and the proportion of patients who achieved a complete remission. Efficacy and safety analyses included all patients who received at least one dose of quizartinib (ie, the intention-to-treat population). Patients with a locally assessed post-treatment bone marrow aspirate or biopsy were included in efficacy analyses by response; all other patients were considered to have an unknown response. This study is registered with ClinicalTrials.gov, number NCT00989261, and with the European Clinical Trials Database, EudraCT 2009-013093-41, and is completed. Findings Between Nov 19, 2009, and Oct 31, 2011, a total of 333 patients were enrolled (157 in cohort 1 and 176 in cohort 2). In cohort 1, 63 (56%) of 112 FLT3-ITD-positive patients and 16 (36%) of 44 FLT3-ITD-negative patients achieved composite complete remission, with three (3%) FLT3-ITD-positive patients and two (5%) FLT3-ITD-negative patients achieving complete remission. In cohort 2, 62 (46%) of 136 FLT3-ITD-positive patients achieved composite complete remission with five (4%) achieving complete remission, whereas 12 (30%) of 40 FLT3-ITD-negative patients achieved composite complete remission with one (3%) achieving complete remission. Across both cohorts (ie, the intention-to-treat population of 333 patients), grade 3 or worse treatment-related treatment-emergent adverse events in 5% or more of patients were febrile neutropenia (76 [23%] of 333), anaemia (75 [23%]), thrombocytopenia (39 [12%]), QT interval corrected using Fridericia's formula (QTcF) prolongation (33 [10%]), neutropenia (31 [9%]), leucopenia (22 [7%]), decreased platelet count (20 [6%]), and pneumonia (17 [5%]). Serious adverse events occurring in 5% or more of patients were febrile neutropenia (126 [38%] of 333; 76 treatment related), acute myeloid leukaemia progression (73 [22%]), pneumonia (40 [12%]; 14 treatment related), QTcF prolongation (33 [10%]; 32 treatment related), sepsis (25 [8%]; eight treatment related), and pyrexia (18 [5%]; nine treatment related). Notable serious adverse events occurring in less than 5% of patients were torsades de pointes (one [<1%]) and hepatic failure (two [1%]). In total, 125 (38%) of 333 patients died within the study treatment period, including the 30-day follow-up. 18 (5%) patients died because of an adverse event considered by the investigator to be treatment related (ten [6%] of 157 patients in cohort 1 and eight [5%] of 176 in cohort 2. Interpretation Single-agent quizartinib was shown to be highly active and generally well tolerated in patients with relapsed or refractory acute myeloid leukaemia, particularly those with FLT3-ITD mutations. These findings confirm that targeting the FLT3-ITD driver mutation with a highly potent and selective FLT3 inhibitor is a promising clinical strategy to help improve clinical outcomes in patients with very few options. Phase 3 studies (NCT02039726; NCT02668653) will examine quizartinib at lower starting doses. Copyright (c) 2018 Elsevier Ltd. All rights reserved.

This randomized, open-label, phase 2b study (NCT01565668) evaluated the efficacy and safety of 2 dosing regimens of quizartinib monotherapy in patients with relapsed/refractory (R/R) FLT3-internal tandem duplication (ITD)-mutated acute myeloid leukemia (AML) who previously underwent transplant or 1 second-line salvage therapy. Patients (N = 76) were randomly assigned to 30- or 60-mg/day doses (escalations to 60 or 90 mg/day, respectively, permitted for lack/loss of response) of single-agent oral quizartinib dihydrochloride. Allelic frequency of at least 10% was defined as FLT3-ITD-mutated disease. Coprimary endpoints were composite complete remission (CRc) rates and incidence of QT interval corrected by Fridericia's formula (QTcF) of more than 480 ms (grade 2 or greater). Secondary endpoints included overall survival (OS), duration of CRc, bridge to transplant, and safety. CRc rates were 47% in both groups, similar to earlier reports with higher quizartinib doses. Incidence of QTcF above 480 ms was 11% and 17%, and QTcF above 500 ms was 5% and 3% in the 30- and 60-mg groups, respectively, which is less than earlier reports with higher doses of quizartinib. Median OS (20.9 and 27.3 weeks), duration of CRc (4.2 and 9.1 weeks), and bridge to transplant rates (32% and 42%) were higher in the 60-mg groups than in the 30-mg group. Dose escalation occurred in 61% and 14% of patients in the 30- and 60-mg groups, respectively. This high clinical activity of quizartinib at the evaluated doses is consistent with previous reports with an improved safety profile. Need to dose-escalate more than half of patients who received quizartinib 30 mg also supports further investigation of treatment with quizartinib 60 mg/day.

8534 Background: In phase II trials, postoperative therapy with Canvaxin allogeneic melanoma cell vaccine plus Bacillus Calmette-Guerin (BCG) improved the survival of patients with stage IV melanoma. A multicenter, phase III placebo-controlled study was undertaken to investigate the vaccine’s efficacy. Methods: After complete resection of melanoma involving up to 5 distant sites, patients were randomized to treatment with BCG plus Canvaxin (BCG-Canvaxin) or BCG plus placebo (BCG-placebo). The primary endpoint was overall survival (OS); secondary endpoints were disease-free survival (DFS) and skin test responsiveness to the study agent. Results: Between May 1998 and April 2005, 496 patients were randomized. In April 2005, entry to the study was terminated due to low probability of demonstrating treatment differences. However, 256 patients from sites enrolled in a follow-up study were monitored until March 2010. Median OS and 5-year and 10-year rates of OS were 39.1 months, 43.3% and 33.3%, respectively, in the BCG-placebo group, versus 34.9 months, 42.5% and 36.4%, respectively, in the BCG-Canvaxin group (hazard ratio, 1.053; 95% confidence interval, 0.81 to 1.36; p=0.6964). Median DFS, 5-year DFS, and 10-year DFS were 7.6 months, 23.8% and 21.7%, respectively, for the BCG-placebo group, versus 8.5 months, 30.0%, and 30.0%, respectively, for the BCG-Canvaxin group (hazard ratio, 0.882; 95% confidence interval, 0.708 to 1.097; p=0.2595). Positive skin test results correlated with improved survival. Conclusions: BCG-Canvaxin was not superior to BCG-placebo, but the highly favorable long-term survival for combined groups indicates that complete metastasectomy should be considered as initial therapy for patients with resectable stage IV melanoma (ClinicalTrials.gov identifier: NCT00052156).

1. Quizartinib absorption, metabolism and excretion were characterized in six healthy men receiving a single oral dose of 60 mg (≈100 μCi) of [14C]-quizartinib. Blood, plasma, urine and faeces were collected ≤336 h postdose. 2. Four hours postdose, maximum mean ± SD blood radioactivity concentrations were 296 ± 67.4 ng equivalents/g. A mean ± SD of 1.64 ± 0.482% and 76.3 ± 6.23% of the dose was recovered in urine and faeces, respectively, within 336 h postdose. 3. Radio-detector high-performance liquid chromatography (radio-HPLC) and liquid chromatography-mass spectrometry (LC-MS) showed two main radioactive peaks in plasma, unchanged quizartinib and mono-oxidative metabolite, AC886. Five additional metabolites in plasma were identified by LC-MS, but low levels prevented radio-HPLC detection. Although unchanged quizartinib was the main radioactive component in faeces (mean, 4.0% of administered dose), 15 metabolites representing a mean of 1.0-3.5% of administered dose were found. Quizartinib was predominantly metabolized by phase I biotransformations (oxidation, reduction, dealkylation, deamination, hydrolysis and combinations thereof). 4. This study indicated that quizartinib was rapidly and orally bioavailable, extensively metabolized, with AC886 as the major circulating metabolite, and predominantly eliminated in faeces. Quizartinib was well tolerated in the subjects.

FLT3-ITD-mutated acute myeloid leukemia (AML) has very high risk of relapse and is associated with poor outcome following allogeneic hematopoietic-cell transplant (allo-HCT). This two-part, phase 1, multicenter, open-label, sequential-group, dose-escalation study aimed to determine dose-limiting toxicities (DLTs), maximum tolerated dose (MTD), and safety/tolerability of quizartinib, a selective and highly potent FLT3 inhibitor, when administered as maintenance therapy after allo-HCT. Thirteen subjects with documented FLT3-ITD-mutated AML in morphological remission following allo-HCT received one of two quizartinib dihydrochloride dose levels (DL): 40 mg/d (DL1; n = 7) and 60 mg/d (DL2; n = 6), administered orally in 28-day cycles for up to 24 cycles. Median age of participants was 43 years. All subjects received human leukocyte antigen (HLA)-matched allo-HCT. One subject treated at DL1 and 1 treated at DL2 had DLTs that required drug interruption (grade 3 gastric hemorrhage and grade 3 anemia, respectively). Ten subjects (77%) received quizartinib for >1 year; 5 (38%) completed 24 cycles. Four subjects (31%) discontinued quizartinib due to adverse events. One subject (8%) experienced relapse during cycle 1 and discontinued treatment. Most common grade 3/4 adverse events were neutropenia (23%), anemia (15%), leukopenia (15%), lymphopenia (15%), and thrombocytopenia (15%). This study demonstrated acceptable tolerability and early evidence of reduced relapse rate following allo-HCT with quizartinib maintenance compared to historical cohorts. No MTD was identified, but 60 mg daily was selected as highest dose for continuous daily administration based on randomized comparison of daily 30 and 60 mg doses in relapsed/refractory AML.

Abstract Purpose: To determine a safe and biologically active dose of quizartinib (AC220), a potent and selective class III receptor tyrosine kinase (RTK) FLT3 inhibitor, in combination with salvage chemotherapy in children with relapsed acute leukemia. Experimental Design: Quizartinib was administered orally to children with relapsed AML or MLL-rearranged ALL following 5 days of high-dose cytarabine and etoposide (AE). A 3+3 dose escalation design was used to identify a safe and biologically active dose. Plasma inhibitory assay (PIA) testing was performed weekly to determine biologic activity. Results: Toxicities were consistent with intensive relapsed leukemia regimens. One of 6 patients experienced a dose-limiting toxicity (DLT) at 40 mg/m2/day (elevated lipase) and 1 of 9 had a DLT (hyperbilirubinemia) at the highest tested dose of 60 mg/m2/day. Of 17 response evaluable patients, 2 had complete response (CR), 1 complete response without platelet recovery (CRp), 1 complete response with incomplete neutrophil and platelet recovery (CRi), 10 stable disease (SD), and 3 progressive disease (PD). Of 7 FLT3-ITD patients, 1 achieved CR, 1 CRp, 1 Cri, and 4 SD. FLT3-ITD patients, but not FLT3 wild-type (WT) patients, had significantly lower blast counts post-quizartinib. FLT3 phosphorylation was completely inhibited in all patients. Conclusions: Quizartinib plus intensive chemotherapy is well tolerated at 60 mg/m2/day with near complete inhibition of FLT3 phosphorylation in all patients. The favorable toxicity profile, pharmacodynamic activity, and encouraging response rates warrant further testing of quizartinib in children with FLT3-ITD AML. Clin Cancer Res; 22(16); 4014–22. ©2016 AACR.

Internal tandem duplications (ITD) are the most commonly observed FLT3 mutations in AML and are associated with decreased survival. In order to achieve meaningful clinical responses with FLT3 inhibitors, sustained inhibition of FLT3 must be achieved [Pratz, Blood 2009]. Quizartinib (Q) is an oral, potent and selective FLT3 inhibitor with an IC50 ≤ 1 nM. In a Phase (Ph) 1 study, the maximum tolerated dose was 200 mg/day (d) in patients (pt) with R/R AML. QTc prolongation was the dose limiting toxicity (Cortes, JCO 2013). In Ph 2 trials, QTc prolongation >500 msec was observed in 15%-17% of pt treated with Q doses of 90 mg/d and 135 mg/d (Cortes ASCO 2013, Martinelli, ASCO 2013). Composite complete response (CRc) rates and overall survival (OS) in FLT3-ITD(+) pt in these studies were similar, respectively. (Levis EHA 2013)] Therefore, we conducted a pre-clinical, pharmacokinetic (PK), and clinical study to find an optimal dosing strategy balancing efficacy with safety for use in future trials.

TPS7073 Background: Internal tandem duplications (ITDs) are commonly observed FLT3 mutations in AML and are a very poor prognostic factor for duration of response and overall survival (OS). While standard chemotherapy (SC) induces a high rate of complete remission (CR) in FLT3-ITD AML, the relapse rate is high with a median time to relapse of ≈6 months vs 9-11 months for other AML subtypes (Levis M. ASH Education Book 2013:220-226). Currently, no approved therapies target the FLT3-ITD mutation. Q is an oral, highly potent, and selective FLT3-ITD inhibitor. Q monotherapy results in composite CR (CRc) rates up to ≈46% in relapsed/refractory FLT3-ITD+ AML (Levis M, ASCO 2014 [abstr 7093]). Q has been safely administered with SC in pts with NDx AML (Burnett AK, ASH 2013 [abstr 622]). Here, we describe a P3, randomized, double-blind, P-controlled trial of Q in combination with IND and CON and as MN in pts with NDx FLT3-ITD+ AML. Methods: Pts 18-75 years old with NDx FLT3-ITD+ AML are eligible. During IND, cytarabine (CY) 100 mg/m2/d will be given for 7 days along with investigator’s choice of anthracycline (either daunorubicin 60 mg/m2/d or idarubicin 12 mg/m2/d) on D1-3. Q/P will be given QD for 14 days starting on C1 D8. If pts require a second cycle of IND, investigators may choose a standard 7+3 or 5+2 regimen with Q/P starting on D8 or 6, respectively. Pts achieving CR, CR with incomplete platelet recovery (CRp), or CR with incomplete neutrophil recovery (CRi) after IND will receive CON. Options include high-dose (HD) CY plus Q/P, allogeneic hematopoietic stem cell transplant (alloHSCT), or HD CY plus Q/P followed by alloHSCT. Pts with CR, CRp, or CRi after CON will receive Q/P MN therapy for a maximum of 12 cycles. The primary endpoint is centrally adjudicated event-free survival, and key secondary endpoints are OS, CR rate, CRc rate, and % of pts achieving CR with no evidence of minimal residual disease (MRD) following IND. MRD will be assessed by a PCR-based assay that detects residual FLT3-ITD mutation. The study will enroll ≈536 pts at 250 centers worldwide (NCT02668653). Results: NA Conclusions: NA Clinical trial information: NCT02668653.

Introduction: The prognosis of patients with a FLT3-ITD mutation in acute myeloid leukemia (AML) is worse than FLT3 wild type patients, with increased early relapse including after allogeneic stem cell transplantation (SCT) and with a poor response to salvage. FLT3-ITD mutant patients who relapse after SCT or fail salvage chemotherapy have a dismal prognosis with no approved treatment options. Quizartinib (AC220), an oral FLT3 receptor tyrosine kinase inhibitor, has shown a remission rate of 44%, and median overall survival of 23 weeks in FLT3-ITD mutant patients who were relapsed or refractory to 2nd line treatment, or relapsed following SCT in a non-randomised phase 2 study [1]. While these outcomes compare favourably to published data, which give a median survival of 1.5 months in all comers [2], and median survival in FLT3-ITD mutant patients of 13 weeks following first relapse [3], there is an overall paucity of data available for the FLT3-ITD+ subpopulation examined in the quizartinib studies . The UK NCRI database is the largest dataset for FLT3-ITD+ AML patients, containing 6872 patients with ITD status (1388 mutant) and systematic collection of data from diagnosis with follow-up for at least 5 years or to death. Methods: 97 FLT3-ITD+ patients from the AC220-002 study who had received intensive chemotherapy, and had either relapsed following SCT (n=39); or were relapsed (n=53) or refractory (n=5) following salvage therapy prior to enrolment were identified. The equivalent eligibility criteria were applied to the UK MRC/NCRI database of AML trial patients treated intensively from 1988-2013 who had confirmed FLT3-ITD mutation: 183 patients matching the same criteria were identified (post-SCT n= 65; relapsed n=99; refractory n=19). Patients in this group received only recognised intensive chemotherapy regimens prior to fulfilling the eligibility criteria. To reflect the screening period in AC220-002, patients in the MRC/NCRI cohort entered the analysis 14 days following being identified as relapsed/refractory. The primary endpoint was overall survival. Multivariable Cox/logistic regression was performed stratified for known prognostic factors, including route to eligibility (post SCT/relapsed/refractory). Sensitivity analyses were performed excluding deaths within 14 and 28 days from eligibility from the MRC/NCRI cohort only to allow for patients who might not have been considered for quizartinib treatment on grounds of fitness. Results: There was no significant difference in the ages of the two cohorts (median age AC220-002 47y vs. MRC 48y). Outcomes in the MRC/NCRI cohort did not improve over time from 1988-2013 (p=0.7). Analyses were performed adjusted for route to eligibility, ITD allelic ratio, duration of remission (in relapsed patients), and cytogenetics. Overall survival was improved in the Quizartinib patients (adjusted hazard ratio (HR) 0.40 (0.29-0.55) p Discussion: Quizartinib has previously shown activity in relapsed/refractory patients in a large Phase 2 single arm study, and is currently being studied in a randomized Phase 3 study vs. standard salvage chemotherapy. This analysis examines a patient population that has failed salvage therapy or SCT and for whom there is no standard therapy. It confirms the prolonged overall survival seen in the Phase 2 study when compared to an equivalent large historical cohort of previously intensively treated patients from the UK MRC/NCRI trials, with median survival in quizartinib patients was 159 days compared to 56 days in the historical cohort. Even if deaths within 28 days are excluded entirely from the MRC/NCRI group, there is a highly significant survival benefit for quizartinib. Overall, the activity seen in the AC220-002 Phase 2 study is greater than that seen in comparable patients in a large historical cohort. [1] Levis M et al. ASH meeting Abstr 615, 2014. [2] Giles F et al. Cancer 104 (3), p547, 2005. [3] Ravandi F et al. Leukemia Research 34, p752, 2010. Disclosures Off Label Use: Quizartinib for AML. Gammon:Ambit: Employment. Trone:Ambit: Employment.

7100 Background: The presence of FLT3-internal tandem duplication (ITD) in patients (pts) with acute myeloid leukemia (AML) is associated with early relapse and poor survival. Quizartinib (AC220) is an orally active inhibitor of the FLT3 receptor tyrosine kinase being developed for the treatment of pts with FLT3-ITD(+) AML. This randomized, open-label, study was conducted to assess the effect of two different dosages of quizartinib in FLT3-ITD+ pts, aged 18 years or older, with relapsed or refractory AML after either one-second line therapy or HSCT. Methods: Pts were randomized to quizartinib 30 mg/day (Group A) or 60 mg/day (Group B) given orally during 28-day continuous treatment cycles, until relapse, intolerance or proceeding to HSCT. Primary endpoint was the rate of CRc (CR+CRp+CRi). Results: Seventy six pts were randomized equally to the two arms. Demographics and baseline characteristics were balanced between the two arms except for age over 60 years (42% Group A, 26% Group B) and the percentage with secondary AML (8% Group A, 18% Group B). The analysis included a minimum of 8 weeks of follow-up. The median duration of treatment in Group A was 10.9 weeks (range 2.1 to 24.9+ weeks) and 11.0 weeks (range 2.6 to 26 weeks) in Group B. The CRc rate in both groups was 47% and the overall response rate (CRc + partial response (PR)) was 61% in Group A and 71% in Group B. 32% of pts in Group A and 42% in Group B were able to receive a HSCT, mostly after achieving CRc or PR. The median overall survival was 20.7 weeks in Group A; and 25.4 weeks in Group B with 35 of the 76 patients alive at last follow-up (range: 7.4 – 40.4+ weeks). Grade 2 or greater QTcF prolongation occurred in 11% Group A pts and in 17% Group B pts. The most common treatment related adverse events occurring in 15% or more pts were diarrhea (18%), febrile neutropenia (16%), and QT prolongation (15%). Conclusions: Quizartinib in second salvage or post HSCT FLT3-ITD+ AML demonstrated a high degree of efficacy (CRc 47%) with an acceptable safety profile, specifically decreased QTcF prolongation rates compared to higher doses used previously. Further analysis with additional follow-up will be available for presentation. Clinical trial information: NCT01565668.

7093^ Background: For FLT3-ITD(+) AML patients (pts) who are relapsed or refractory to chemotherapy, allogeneic HSCT offers the best prospect for long-term survival. Pts are unlikely to undergo HSCT unless their blast count can be reduced to an acceptable minimum, ideally below 5% blasts, which defines composite complete response (CRc: CR + CRp + CRi). Quizartinib is an orally active inhibitor of the FLT3 receptor tyrosine kinase being developed for the treatment of AML pts. We present a new analysis from FLT3-ITD(+) pts who were relapsed or refractory to salvage therapy or HSCT treated with quizartinib across two Phase 2 studies in a total of 212 subjects. Methods: In Study A, pts received 90-200 mg/day quizartinib; in Study B, pts were randomized to either 30 mg/day or 60 mg/day quizartinib given orally during continuous 28 day cycles. Results: Median baseline blast count in Study A was 81% and 67% in Study B. Median age in Study A was 50yrs and 55yrs in Study B. In Study A, 47 of 136 (35%) proceeded to HSCT; of these 26/47 (55%) had achieved a CRc and 18/47 (38%) a PR prior to HSCT. In Study B 28/76 (37%) pts proceeded to HSCT and of these 23/28 (82%) had achieved a CRc and 4/28 (14%) achieved a PR prior to HSCT. In Study A, pts proceeding to HSCT had a median overall survival (OS) of 34.1 weeks and a 1 yr survival rate of 36% compared to an OS of 18.4 weeks and 1 yr survival of 12% for pts not undergoing HSCT. In Study B, pts randomized to 30 mg/day quizartinib and who underwent HSCT had an OS of 31 weeks compared to 19 weeks for pts without HSCT; pts treated with 60 mg/day and who underwent HSCT had an OS of 28.1 weeks compared to 16.3 weeks for pts without HSCT. Conclusions: Pts able to receive a HSCT after response to quizartinib have an improved outcome compared to those who did not have a HSCT. The ability of quizartinib to lower the blast count in a high percentage of pts (46% achieved a CRc) and bridge these pts to a potentially curative HSCT, with an acceptable safety profile, represents an important clinical benefit from quizartinib. Clinical trial information: NCT00989261 and NCT01565668.

FMS-like tyrosine kinase 3 internal tandem duplications (FLT3-ITD) in acute myeloid leukemia (AML) are associated with early relapse after standard chemotherapy and poor survival. Hematopoietic cell transplantation (HCT) is a recommended treatment for patients with FLT3-ITD(+) AML. However, a high rate of relapse after a HCT is observed when compared to FLT3-ITD(-) patients with the 2 year relapse rate of 30% vs. 16% in FLT3-ITD(+) and FLT3-ITD(-) patients, respectively (Brunet, J. Clin. Oncol. 2012). Quizartinib (AC220) is an oral FLT3 receptor tyrosine kinase inhibitor that has shown a high level of single agent activity in nearly 500 patients with FLT3(+) relapsed or refractory AML and is currently in a Phase 3 study.

7021 Background: Advanced age and FMS-like tyrosine kinase 3 internal tandem duplications (FLT3-ITD) in acute myeloid leukemia (AML) are associated with early relapse after standard chemotherapy and poor survival. Quizartinib (AC220), an oral FLT3 inhibitor active against ITD mutant and wild type FLT3, has shown promising activity in Ph 1 and 2 studies. Methods: Patients (pts) in a Ph 2 open label study (N = 333) of quizartinib monotherapy included 154 aged ≥60 y with known FLT3-ITD status and AML relapsed in <1 y or refractory to 1st line chemotherapy. Median duration of treatment was 14.2 wks (range 0.1–70.6 wks) for FLT3-ITD(+) pts and 9.5 wks (range 1.1–77.0 wks) for FLT3-ITD(-) pts. The composite complete remission (CRc) rate included complete remission (CR), complete remission with incomplete platelet recovery (CRp), and complete remission with incomplete hematologic recovery (CRi). Results: Of 110 FLT3-ITD(+) pts, 63 (57%) had a CRc (3 CR, 4 CRp, 56 CRi). Of 44 FLT3-ITD(-) pts, 16 (36%) had a CRc (2 CR, 1 CRp, 13 CRi). Median overall survival (OS) in FLT3-ITD(+) pts was 25.3 wks and 16/110 (15%) survived >52 wks. The median age of these pts surviving >52 wks was 69.5 y (range 66–80 y) and median OS was 76.3 wks (range 56.9–96.0 wks). All of these pts responded to quizartinib (2 CR, 2 CRp, 8 CRi, 4 partial remission [PR]). 2 pts were still alive >1 ½ y (OS 93.0 and 96.0 wks). Median OS in FLT3-ITD(-) pts was 19.1 wks and 6/44 FLT3-ITD(-) pts (14%) survived >52 wks. The median age of these pts was 70.0 y (range 65–77 y) and their median survival was 76.6 wks (range 54.9–98.4 wks). 5 of these pts responded to quizartinib (1 CR, 3 CRi, 1 PR). Conclusions: These data for an FLT3-targeted agent show encouraging survival in a subset of elderly pts with relapsed/refractory FLT3-ITD(+) AML. Clinical trial information: NCT00989261. [Table: see text]

Abstract Abstract 3605 Background: AC220 is a novel class III receptor tyrosine kinase (RTK) inhibitor that is potent and highly selective for mutant and wild type (WT) FLT3 and other class III RTK's including KIT, CSF1R, RET and PDGFR. In childhood acute myeloid leukemia (AML), ∼18% of children have FLT3 internal tandem duplication mutations (FLT3-ITD), and ∼10% high WT FLT3 expression. FLT3-ITD is associated with poor prognosis. In childhood acute lymphoblastic leukemia (ALL), the highest levels of FLT3 mRNA expression occur in cases of infants (80%) and childhood ALL with MLL rearrangements (MLL-r) (5%), both conferring poor prognosis.1,2 Study Design: TACL 2009–004is a first-in-children study using AC220 in combination with cytarabine and etoposide. Children > 1 month and < 21 years of age with relapsed/refractory AML or MLL-rearranged ALL are eligible. A standard 3+3 dose escalation design is utilized. The three doses tested (25, 40 and 60 mg/m2/day) are significantly lower than those tested in adults. Dose escalation past 60 mg/m2 occurs only if adequate biologic activity as determined by a plasma inhibitory assay (PIA) is not achieved. Intravenous (IV) cytarabine (1 gm/m2/dose every 12 hours) and IV etoposide (150 mg/m2/dose daily) are given over 5 days. AC220 is administered once daily as an oral solution on days 7–28. Patients can receive up to 2 courses of therapy. PIA testing is performed at trough time points weekly during exposure to AC220 to determine biologic activity. Results: To date, 13 patients (pts) were enrolled and 12 are evaluable for toxicity and response. One pt died from infectious complications (not drug-related) after a single dose of AC220 and was replaced. Median age at study entry was 10.2 years (range 11 mo – 20 yrs), average number of prior regimens was 2.8 (range 1–5), and 5 pts had prior stem cell transplant. Nine pts had relapsed AML, 2 had relapsed MLL-r ALL, and 1 had secondary AML. Of patients with AML, 4 had FLT3-ITD mutations and one had a D835 mutation. Toxicities were consistent with intensive relapsed leukemia regimens. Across all dose levels, non-hematologic toxicities ≥ grade 3 attributed to AC220 included vomiting (n=1), elevated transaminases (n=1), anorexia (n=2), and infection (n=3). One pt experienced a dose-limiting toxicity (DLT) on dose level 2 (40 mg/m2/day) of recurrent grade 3 elevated lipase. Dose level 2 was expanded to 6 pts without additional DLTs. Of 3 pts treated at 60 mg/m2/day, there have been no DLTs. Near total (>99%) inhibition of FLT3 phosphorylation by PIA is seen in every patient across all dose levels. Of 12 pts evaluable for response to date, 1 patient achieved a complete response (CR), 3 achieved complete response with incomplete neutrophil and platelet recovery (CRi), 5 had stable disease (SD), and 3 had progressive disease (PD). Responses in the 4 FLT3-ITD pts include 1 CR, 2 CRi and 1 SD. The FLT3-ITD patient with SD had reduction in marrow blasts without peripheral blood count recovery. An additional 6 pts will be enrolled at 60 mg/m2/day to complete safety evaluation and confirm biologic activity. Conclusions: AC220 plus intensive chemotherapy is well tolerated at doses up to 60 mg/m2/day with near complete inhibition of FLT3 phosphorylation in all pts tested to date. Response rates to date in pre-treated children with relapsed FLT3-ITD AML are encouraging. Disclosures: Off Label Use: AC220 in relapsed/refractory pediatric acute leukemia. Gammon:Ambit Biosciences: Employment.