Final phase I substudy results of ivosidenib in patients with mutant IDH1 relapsed/refractory myelodysplastic syndrome.

Ivosidenib is a first-in-class mutant isocitrate dehydrogenase 1 (mIDH1) inhibitor and has shown efficacy and tolerability in patients with advanced mIDH1 hematologic malignancies, leading to approval in front-line and relapsed/refractory (R/R) mIDH1 AML populations. We report final data from a phase I single-arm substudy (NCT02074839) of patients with R/R mIDH1 MDS following failure of standard-of-care therapies. Oral ivosidenib was taken once daily on days 1-28 in 28-day cycles. Primary objectives were to determine safety, tolerability, and clinical activity. The primary efficacy endpoint was the complete remission + partial remission (CR+PR) rate. Nineteen patients were enrolled; 18 were included in the efficacy analysis. Treatment-related adverse events occurred in eight (42.1%) patients, including a grade 1 QT interval prolongation in one (5.3%) patient and grade 2 differentiation syndrome in two (10.5%) patients. Rates of CR+PR and objective response (CR +PR+marrow CR) were 38.9% (95% confidence interval [CI]: 17.3, 64.3) and 83.3% (95% CI: 58.6, 96.4), respectively. Kaplan-Meier estimates showed a 68.6% probability of patients in CR achieving a remission duration of >=5 years, and a median OS of 35.7 months. Of note, 71.4% and 75.0% baseline red blood cell (RBC) and platelet transfusion-dependent patients, respectively, became transfusion independent (TI; no transfusion >=56 days); 81.8% and 100% of baseline RBC and platelet TI patients, respectively, remained TI. One (5.3%) patient proceeded to a hematopoietic stem cell transplant by data cut-off. In conclusion, ivosidenib is clinically active, with durable remissions and a manageable safety profile observed in patients with mIDH1 R/R MDS.

Impact of prior therapies and subsequent transplantation on outcomes in adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia treated with brexucabtagene autoleucel in ZUMA-3.

BACKGROUND: Brexucabtagene autoleucel (brexu-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved in the USA for adults with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) and in the European Union for patients ≥26 years with R/R B-ALL. After 2 years of follow-up in ZUMA-3, the overall complete remission (CR) rate (CR+CR with incomplete hematological recovery (CRi)) was 73%, and the median overall survival (OS) was 25.4 months in 78 Phase 1 and 2 patients with R/R B-ALL who received the pivotal dose of brexu-cel. Outcomes by prior therapies and subsequent allogeneic stem cell transplantation (alloSCT) are reported. METHODS: Eligible adults had R/R B-ALL and received one infusion of brexu-cel (1×106 CAR T cells/kg) following conditioning chemotherapy. The primary endpoint was the CR/CRi rate per central review. Post hoc subgroup analyses were exploratory with descriptive statistics provided. RESULTS: Phase 1 and 2 patients (N=78) were included with median follow-up of 29.7 months (range, 20.7-58.3). High CR/CRi rates were observed across all prior therapy subgroups examined: 1 prior line of therapy (87%, n=15) and ≥2 prior lines (70%, n=63); prior blinatumomab (63%, n=38) and no prior blinatumomab (83%, n=40); prior inotuzumab (59%, n=17) and no prior inotuzumab (77%, n=61); and prior alloSCT (76%, n=29) and no prior alloSCT (71%, n=49). The frequency of Grade ≥3 cytokine release syndrome, neurological events, and treatment-related Grade 5 adverse events were largely similar among prior therapy subgroups.Median duration of remission (DOR) in responders with (n=14) and without (n=43) subsequent alloSCT was 44.2 (95% CI, 8.1 to not estimable (NE)) and 18.6 months (95% CI, 9.4 to NE); median OS was 47.0 months (95% CI, 10.2 to NE) and not reached (95% CI, 23.2 to NE), respectively. Median DOR and OS were not reached in responders without prior or subsequent alloSCT (n=22). CONCLUSIONS: In ZUMA-3, adults with R/R B-ALL benefited from brexu-cel, regardless of prior therapies and subsequent alloSCT status, though survival appeared better in patients without certain prior therapies and in earlier lines of therapy. Additional studies are needed to determine the impact prior therapies and subsequent alloSCT have on outcomes of patients who receive brexu-cel.

Entospletinib with decitabine in acute myeloid leukemia with mutant TP53 or complex karyotype: A phase 2 substudy of the Beat AML Master Trial.

BACKGROUND: Patients with acute myeloid leukemia (AML) who have tumor protein p53 (TP53) mutations or a complex karyotype have a poor prognosis, and hypomethylating agents are often used. The authors evaluated the efficacy of entospletinib, an oral inhibitor of spleen tyrosine kinase, combined with decitabine in this patient population. METHODS: This was a multicenter, open-label, phase 2 substudy of the Beat AML Master Trial (ClinicalTrials.gov identifier NCT03013998) using a Simon two-stage design. Eligible patients aged 60 years or older who had newly diagnosed AML with mutations in TP53 with or without a complex karyotype (cohort A; n = 45) or had a complex karyotype without TP53 mutation (cohort B; n = 13) received entospletinib 400 mg twice daily with decitabine 20 mg/m2 on days 1-10 every 28 days for up to three induction cycles, followed by up to 11 consolidation cycles, in which decitabine was reduced to days 1-5. Entospletinib maintenance was given for up to 2 years. The primary end point was complete remission (CR) and CR with hematologic improvement by up to six cycles of therapy. RESULTS: The composite CR rates for cohorts A and B were 13.3% (95% confidence interval, 5.1%-26.8%) and 30.8% (95% confidence interval, 9.1%-61.4%), respectively. The median duration of response was 7.6 and 8.2 months, respectively, and the median overall survival was 6.5 and 11.5 months, respectively. The study was stopped because the futility boundary was crossed in both cohorts. CONCLUSIONS: The combination of entospletinib and decitabine demonstrated activity and was acceptably tolerated in this patient population; however, the CR rates were low, and overall survival was short. Novel treatment strategies for older patients with TP53 mutations and complex karyotype remain an urgent need.

Two-year follow-up of KTE-X19 in patients with relapsed or refractory adult B-cell acute lymphoblastic leukemia in ZUMA-3 and its contextualization with SCHOLAR-3, an external historical control study.

BACKGROUND: Brexucabtagene autoleucel (KTE-X19) is an autologous anti-CD19 CAR T-cell therapy approved in the USA to treat adult patients with relapsed or refractory B-precursor acute lymphoblastic leukemia (R/R B-ALL) based on ZUMA-3 study results. We report updated ZUMA-3 outcomes with longer follow-up and an extended data set along with contextualization of outcomes to historical standard of care. METHODS: Adults with R/R B-ALL received a single infusion of KTE-X19 (1 × 106 CAR T cells/kg). Long-term post hoc subgroup assessments of ZUMA-3 were conducted. Outcomes from matched patients between historical clinical trials and ZUMA-3 patients were assessed in the retrospective historical control study SCHOLAR-3. RESULTS: After 26.8-months median follow-up, the overall complete remission (CR) rate (CR + CR with incomplete hematological recovery) among treated patients (N = 55) in phase 2 was 71% (56% CR rate); medians for duration of remission and overall survival (OS) were 14.6 and 25.4 months, respectively. Most patients responded to KTE-X19 regardless of age or baseline bone marrow blast percentage, but less so in patients with > 75% blasts. No new safety signals were observed. Similar outcomes were observed in a pooled analysis of phase 1 and 2 patients (N = 78). In SCHOLAR-3, the median OS for treated patients from ZUMA-3 (N = 49) and matched historical controls (N = 40) was 25.4 and 5.5 months, respectively. CONCLUSIONS: These data, representing the longest follow-up of CAR T-cell therapy in a multicenter study of adult R/R B-ALL, suggest that KTE-X19 provides a clinically meaningful survival benefit with manageable toxicity in this population. TRIAL REGISTRATION: NCT02614066.

Impact of Venetoclax and Azacitidine in Treatment-Naïve Patients with Acute Myeloid Leukemia and IDH1/2 Mutations.

PURPOSE: To evaluate efficacy and safety of venetoclax + azacitidine among treatment-naïve patients with IDH1/2-mutant (mut) acute myeloid leukemia (AML). PATIENTS AND METHODS: Data were pooled from patients enrolled in a phase III study (NCT02993523) that compared patients treated with venetoclax + azacitidine or placebo + azacitidine and a prior phase Ib study (NCT02203773) where patients were treated with venetoclax + azacitidine. Enrolled patients were ineligible for intensive therapy due to age ≥75 years and/or comorbidities. Patients on venetoclax + azacitidine received venetoclax 400 mg orally (days 1-28) and azacitidine (75 mg/m2; days 1-7/28-day cycle). RESULTS: In the biomarker-evaluable population, IDH1/2mut was detected in 81 (26%) and 28 (22%) patients in the venetoclax + azacitidine and azacitidine groups. Composite complete remission [CRc, complete remission (CR)+CR with incomplete hematologic recovery (CRi)] rates (venetoclax + azacitidine/azacitidine) among patients with IDH1/2mut were 79%/11%, median duration of remission (mDoR) was 29.5/9.5 months, and median overall survival (mOS) was 24.5/6.2 months. CRc rates among patients with IDH1/2 wild-type (WT) were 63%/31%, mDoR 17.5/10.3 months, and mOS 12.3/10.1 months. In patients with IDH1mut, CRc rates (venetoclax + azacitidine/azacitidine) were 66.7%/9.1% and mOS 15.2/2.2 months. In patients with IDH2mut, CRc rates were 86.0%/11.1% and mOS not reached (NR)/13.0 months. Patients with IDH1/2 WT AML treated with venetoclax + azacitidine with poor-risk cytogenetics had inferior outcomes compared with patients with IDH1/2mut, who had superior outcomes regardless of cytogenetic risk (mOS, IDH1/2mut: intermediate-risk, 24.5 months; poor-risk, NR; IDH1/2 WT: intermediate, 19.2 and poor, 7.4 months). There were no unexpected toxicities in the venetoclax + azacitidine group. CONCLUSIONS: Patients with IDH1/2mut who received venetoclax + azacitidine had high response rates, durable remissions, and significant OS; cytogenetic risk did not mitigate the favorable outcomes seen from this regimen for IDH1/2mut. See related commentary by Perl and Vyas, p. 2719.

Results of a randomized phase 3 study of oral sapacitabine in elderly patients with newly diagnosed acute myeloid leukemia (SEAMLESS).

BACKGROUND: Acute myeloid leukemia (AML) is fatal in elderly patients who are unfit for standard induction chemotherapy. The objective of this study was to evaluate the survival benefit of administering sapacitabine, an oral nucleoside analogue, in alternating cycles with decitabine, a low-intensity therapy, to elderly patients with newly diagnosed AML. METHODS: This randomized, open-label, phase 3 study (SEAMLESS) was conducted at 87 sites in 11 countries. Patients aged ≥70 years who were not candidates for or chose not to receive standard induction chemotherapy were randomized 1:1 to arm A (decitabine in alternating cycles with sapacitabine) received 1-hour intravenous infusions of decitabine 20 mg/m2 once daily for 5 consecutive days every 8 weeks (first cycle and subsequent odd cycles) and sapacitabine 300 mg twice daily on 3 consecutive days per week for 2 weeks every 8 weeks (second cycle and subsequent even cycles) or to control arm C who received 1-hour infusions of decitabine 20 mg/m2 once daily for 5 consecutive days every 4 weeks. Prior hypomethylating agent therapy for preexisting myelodysplastic syndromes or myeloproliferative neoplasms was an exclusion criterion. Randomization was stratified by antecedent myelodysplastic syndromes or myeloproliferative neoplasms, white blood cell count (<10 × 109 /L and ≥10 × 109 /L), and bone marrow blast percentage (≥50% vs <50%). The primary end point was overall survival (OS). Secondary end points were the rates of complete remission (CR), CR with incomplete platelet count recovery, partial remission, hematologic improvement, and stable disease along with the corresponding durations, transfusion requirements, number of hospitalized days, and 1-year survival. The trial is registered at ClinicalTrials.gov (NCT01303796). RESULTS: Between October 2011 and December 2014, 482 patients were enrolled and randomized to receive decitabine administered in alternating cycles with sapacitabine (study arm, n = 241) or decitabine monotherapy (control arm, n = 241). The median OS was 5.9 months on the study arm versus 5.7 months on the control arm (P = .8902). The CR rate was 16.6% on the study arm and 10.8% on the control arm (P = .1468). In patients with white blood cell counts <10 × 109 /L (n = 321), the median OS was higher on the study arm versus the control arm (8.0 vs 5.8 months; P = .145), as was the CR rate (21.5% vs 8.6%; P = .0017). CONCLUSIONS: The regimen of decitabine administered in alternating cycles with sapacitabine was active but did not significantly improve OS compared with decitabine monotherapy. Subgroup analyses suggest that patients with baseline white blood cell counts <10 × 109 /L might benefit from decitabine alternating with sapacitabine, with an improved CR rate and the convenience of an oral drug. These findings should be prospectively confirmed.

KTE-X19 for relapsed or refractory adult B-cell acute lymphoblastic leukaemia: phase 2 results of the single-arm, open-label, multicentre ZUMA-3 study.

BACKGROUND: Despite treatment with novel therapies and allogeneic stem-cell transplant (allo-SCT) consolidation, outcomes in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia remain poor, underlining the need for more effective therapies. METHODS: We report the pivotal phase 2 results of ZUMA-3, an international, multicentre, single-arm, open-label study evaluating the efficacy and safety of the autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy KTE-X19 in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia. Patients were enrolled at 25 sites in the USA, Canada, and Europe. Eligible patients were aged 18 years or older, with Eastern Cooperative Oncology Group performance status of 0-1, and morphological disease in the bone marrow (>5% blasts). After leukapheresis and conditioning chemotherapy, patients received a single KTE-X19 infusion (1 × 106 CAR T cells per kg bodyweight). The primary endpoint was the rate of overall complete remission or complete remission with incomplete haematological recovery by central assessment. Duration of remission and relapse-free survival, overall survival, minimal residual disease (MRD) negativity rate, and allo-SCT rate were assessed as secondary endpoints. Efficacy and safety analyses were done in the treated population (all patients who received a dose of KTE-X19). This study is registered with ClinicalTrials.gov, NCT02614066. FINDINGS: Between Oct 1, 2018, and Oct 9, 2019, 71 patients were enrolled and underwent leukapheresis. KTE-X19 was successfully manufactured for 65 (92%) patients and administered to 55 (77%). The median age of treated patients was 40 years (IQR 28-52). At the median follow-up of 16·4 months (13·8-19·6), 39 patients (71%; 95% CI 57-82, p<0·0001) had complete remission or complete remission with incomplete haematological recovery, with 31 (56%) patients reaching complete remission. Median duration of remission was 12·8 months (95% CI 8·7-not estimable), median relapse-free survival was 11·6 months (2·7-15·5), and median overall survival was 18·2 months (15·9-not estimable). Among responders, the median overall survival was not reached, and 38 (97%) patients had MRD negativity. Ten (18%) patients received allo-SCT consolidation after KTE-X19 infusion. The most common adverse events of grade 3 or higher were anaemia (27 [49%] patients) and pyrexia (20 [36%] patients). 14 (25%) patients had infections of grade 3 or higher. Two grade 5 KTE-X19-related events occurred (brain herniation and septic shock). Cytokine release syndrome of grade 3 or higher occurred in 13 (24%) patients and neurological events of grade 3 or higher occurred in 14 (25%) patients. INTERPRETATION: KTE-X19 showed a high rate of complete remission or complete remission with incomplete haematological recovery in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia, with the median overall survival not reached in responding patients, and a manageable safety profile. These findings indicate that KTE-X19 has the potential to confer long-term clinical benefit to these patients. FUNDING: Kite, a Gilead Company.

KTE-X19 anti-CD19 CAR T-cell therapy in adult relapsed/refractory acute lymphoblastic leukemia: ZUMA-3 phase 1 results.

ZUMA-3 is a phase 1/2 study evaluating KTE-X19, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in adult relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We report the phase 1 results. After fludarabine-cyclophosphamide lymphodepletion, patients received a single infusion of KTE-X19 at 2 × 106, 1 × 106, or 0.5 × 106 cells per kg. The rate of dose-limiting toxicities (DLTs) within 28 days after KTE-X19 infusion was the primary end point. KTE-X19 was manufactured for 54 enrolled patients and administered to 45 (median age, 46 years; range, 18-77 years). No DLTs occurred in the DLT-evaluable cohort. Grade ≥3 cytokine release syndrome (CRS) and neurologic events (NEs) occurred in 31% and 38% of patients, respectively. To optimize the risk-benefit ratio, revised adverse event (AE) management for CRS and NEs (earlier steroid use for NEs and tocilizumab only for CRS) was evaluated at 1 × 106 cells per kg KTE-X19. In the 9 patients treated under revised AE management, 33% had grade 3 CRS and 11% had grade 3 NEs, with no grade 4 or 5 NEs. The overall complete remission rate correlated with CAR T-cell expansion and was 83% in patients treated with 1 × 106 cells per kg and 69% in all patients. Minimal residual disease was undetectable in all responding patients. At a median follow-up of 22.1 months (range, 7.1-36.1 months), the median duration of remission was 17.6 months (95% confidence interval [CI], 5.8-17.6 months) in patients treated with 1 × 106 cells per kg and 14.5 months (95% CI, 5.8-18.1 months) in all patients. KTE-X19 treatment provided a high response rate and tolerable safety in adults with R/R B-ALL. Phase 2 is ongoing at 1 × 106 cells per kg with revised AE management. This trial is registered at www.clinicaltrials.gov as #NCT02614066.

Comanagement Strategy Between Academic Institutions and Community Practices to Reduce Induction Mortality in Acute Promyelocytic Leukemia.

PURPOSE: Acute promyelocytic leukemia (APL) is a curable leukemia with > 90% survival in clinical trials. Population-based studies from Sweden and US SEER data have shown long-term survival rates of 62% and 65.7%, with the lower rate being from a higher percentage of early deaths. METHODS: In this prospective, multicenter trial, we developed a simplified algorithm that focused on prevention and early treatment of the three main causes of death: bleeding, differentiation syndrome, and infection. All patients with a diagnosis of APL were included. The initial 6 months were spent educating oncologists about early deaths in APL. At the time of suspicion of an APL, an expert was contacted. The algorithm was made available followed by discussion of the treatment plan. Communication between expert and treating physician was frequent in the first 2 weeks, during which time most deaths take place. RESULTS: Between September 2013 and April 2016, 120 patients enrolled in the study from 32 hospitals. The median age was 52.5 years, with 39% > 60 years and 25% with an age-adjusted Charlson comorbidity index > 4. Sixty-three percent of patients were managed at community centers. Two patients did not meet the criteria for analysis, and of 118 evaluable patients, 10 died, with an early mortality rate of 8.5%. With a median follow-up of 27.3 months, the overall survival was 84.5%. CONCLUSION: Induction mortality can be decreased and population-wide survival improved in APL with the use of standardized treatment guidelines. Support from experts who have more experience with induction therapy is crucial and helps to improve the outcomes.

Flotetuzumab as salvage immunotherapy for refractory acute myeloid leukemia.

Approximately 50% of acute myeloid leukemia (AML) patients do not respond to induction therapy (primary induction failure [PIF]) or relapse after <6 months (early relapse [ER]). We have recently shown an association between an immune-infiltrated tumor microenvironment (TME) and resistance to cytarabine-based chemotherapy but responsiveness to flotetuzumab, a bispecific DART antibody-based molecule to CD3ε and CD123. This paper reports the results of a multicenter, open-label, phase 1/2 study of flotetuzumab in 88 adults with relapsed/refractory AML: 42 in a dose-finding segment and 46 at the recommended phase 2 dose (RP2D) of 500 ng/kg per day. The most frequent adverse events were infusion-related reactions (IRRs)/cytokine release syndrome (CRS), largely grade 1-2. Stepwise dosing during week 1, pretreatment dexamethasone, prompt use of tocilizumab, and temporary dose reductions/interruptions successfully prevented severe IRR/CRS. Clinical benefit accrued to PIF/ER patients showing an immune-infiltrated TME. Among 30 PIF/ER patients treated at the RP2D, the complete remission (CR)/CR with partial hematological recovery (CRh) rate was 26.7%, with an overall response rate (CR/CRh/CR with incomplete hematological recovery) of 30.0%. In PIF/ER patients who achieved CR/CRh, median overall survival was 10.2 months (range, 1.87-27.27), with 6- and 12-month survival rates of 75% (95% confidence interval [CI], 0.450-1.05) and 50% (95% CI, 0.154-0.846). Bone marrow transcriptomic analysis showed that a parsimonious 10-gene signature predicted CRs to flotetuzumab (area under the receiver operating characteristic curve = 0.904 vs 0.672 for the European LeukemiaNet classifier). Flotetuzumab represents an innovative experimental approach associated with acceptable safety and encouraging evidence of activity in PIF/ER patients. This trial was registered at www.clinicaltrials.gov as #NCT02152956.

Late effects after ablative allogeneic stem cell transplantation for adolescent and young adult acute myeloid leukemia.

There is marked paucity of data regarding late effects in adolescents and young adults (AYAs) who undergo myeloablative conditioning (MAC) allogeneic hematopoietic cell transplantation (HCT) for acute myeloid leukemia (AML). We evaluated late effects and survival in 826 1-year disease-free survivors of MAC HCT for AYA AML, with an additional focus on comparing late effects based upon MAC type (total body irradiation [TBI] vs high-dose chemotherapy only). The estimated 10-year cumulative incidence of subsequent neoplasms was 4% (95% confidence interval [CI], 2%-6%); 10-year cumulative incidence of nonmalignant late effects included gonadal dysfunction (10%; 95% CI, 8%-13%), cataracts (10%; 95% CI, 7%-13%), avascular necrosis (8%; 95% CI, 5%-10%), diabetes mellitus (5%; 95% CI, 3%-7%), and hypothyroidism (3%; 95% CI, 2%-5%). Receipt of TBI was independently associated with a higher risk of cataracts only (hazard ratio [HR], 4.98; P < .0001) whereas chronic graft-versus-host disease (cGVHD) was associated with an increased risk of cataracts (HR, 3.22; P = .0006), avascular necrosis (HR, 2.49; P = .006), and diabetes mellitus (HR, 3.36; P = .03). Estimated 10-year overall survival and leukemia-free survival were 73% and 70%, respectively, and did not differ on the basis of conditioning type. In conclusion, late effects among survivors of MAC HCT for AYA AML are frequent and are more closely linked to cGVHD than type of conditioning.

Ivosidenib induces deep durable remissions in patients with newly diagnosed IDH1-mutant acute myeloid leukemia.

Ivosidenib (AG-120) is an oral, targeted agent that suppresses production of the oncometabolite 2-hydroxyglutarate via inhibition of the mutant isocitrate dehydrogenase 1 (IDH1; mIDH1) enzyme. From a phase 1 study of 258 patients with IDH1-mutant hematologic malignancies, we report results for 34 patients with newly diagnosed acute myeloid leukemia (AML) ineligible for standard therapy who received 500 mg ivosidenib daily. Median age was 76.5 years, 26 patients (76%) had secondary AML, and 16 (47%) had received ≥1 hypomethylating agent for an antecedent hematologic disorder. The most common all-grade adverse events were diarrhea (n = 18; 53%), fatigue (n = 16; 47%), nausea (n = 13; 38%), and decreased appetite (n = 12; 35%). Differentiation syndrome was reported in 6 patients (18%) (grade ≥3 in 3 [9%]) and did not require treatment discontinuation. Complete remission (CR) plus CR with partial hematologic recovery (CRh) rate was 42.4% (95% confidence interval [CI], 25.5% to 60.8%); CR 30.3% (95% CI, 15.6% to 48.7%). Median durations of CR+CRh and CR were not reached, with 95% CI lower bounds of 4.6 and 4.2 months, respectively; 61.5% and 77.8% of patients remained in remission at 1 year. With median follow-up of 23.5 months (range, 0.6-40.9 months), median overall survival was 12.6 months (95% CI, 4.5-25.7). Of 21 transfusion-dependent patients (63.6%) at baseline, 9 (42.9%) became transfusion independent. IDH1 mutation clearance was seen in 9/14 patients achieving CR+CRh (5/10 CR; 4/4 CRh). Ivosidenib monotherapy was well-tolerated and induced durable remissions and transfusion independence in patients with newly diagnosed AML. This trial was registered at www.clinicaltrials.gov as #NCT02074839.

Durable Remissions with Ivosidenib in IDH1-Mutated Relapsed or Refractory AML.

BACKGROUND: Mutations in the gene encoding isocitrate dehydrogenase 1 ( IDH1) occur in 6 to 10% of patients with acute myeloid leukemia (AML). Ivosidenib (AG-120) is an oral, targeted, small-molecule inhibitor of mutant IDH1. METHODS: We conducted a phase 1 dose-escalation and dose-expansion study of ivosidenib monotherapy in IDH1-mutated AML. Safety and efficacy were assessed in all treated patients. The primary efficacy population included patients with relapsed or refractory AML receiving 500 mg of ivosidenib daily with at least 6 months of follow-up. RESULTS: Overall, 258 patients received ivosidenib and had safety outcomes assessed. Among patients with relapsed or refractory AML (179 patients), treatment-related adverse events of grade 3 or higher that occurred in at least 3 patients were prolongation of the QT interval (in 7.8% of the patients), the IDH differentiation syndrome (in 3.9%), anemia (in 2.2%), thrombocytopenia or a decrease in the platelet count (in 3.4%), and leukocytosis (in 1.7%). In the primary efficacy population (125 patients), the rate of complete remission or complete remission with partial hematologic recovery was 30.4% (95% confidence interval [CI], 22.5 to 39.3), the rate of complete remission was 21.6% (95% CI, 14.7 to 29.8), and the overall response rate was 41.6% (95% CI, 32.9 to 50.8). The median durations of these responses were 8.2 months (95% CI, 5.5 to 12.0), 9.3 months (95% CI, 5.6 to 18.3), and 6.5 months (95% CI, 4.6 to 9.3), respectively. Transfusion independence was attained in 29 of 84 patients (35%), and patients who had a response had fewer infections and febrile neutropenia episodes than those who did not have a response. Among 34 patients who had a complete remission or complete remission with partial hematologic recovery, 7 (21%) had no residual detectable IDH1 mutations on digital polymerase-chain-reaction assay. No preexisting co-occurring single gene mutation predicted clinical response or resistance to treatment. CONCLUSIONS: In patients with advanced IDH1-mutated relapsed or refractory AML, ivosidenib at a dose of 500 mg daily was associated with a low frequency of grade 3 or higher treatment-related adverse events and with transfusion independence, durable remissions, and molecular remissions in some patients with complete remission. (Funded by Agios Pharmaceuticals; ClinicalTrials.gov number, NCT02074839 .).

Tetrameric Acetyl-CoA Acetyltransferase 1 Is Important for Tumor Growth.

Mitochondrial acetyl-CoA acetyltransferase 1 (ACAT1) regulates pyruvate dehydrogenase complex (PDC) by acetylating pyruvate dehydrogenase (PDH) and PDH phosphatase. How ACAT1 is "hijacked" to contribute to the Warburg effect in human cancer remains unclear. We found that active, tetrameric ACAT1 is commonly upregulated in cells stimulated by EGF and in diverse human cancer cells, where ACAT1 tetramers, but not monomers, are phosphorylated and stabilized by enhanced Y407 phosphorylation. Moreover, we identified arecoline hydrobromide (AH) as a covalent ACAT1 inhibitor that binds to and disrupts only ACAT1 tetramers. The resultant AH-bound ACAT1 monomers cannot reform tetramers. Inhibition of tetrameric ACAT1 by abolishing Y407 phosphorylation or AH treatment results in decreased ACAT1 activity, leading to increased PDC flux and oxidative phosphorylation with attenuated cancer cell proliferation and tumor growth. These findings provide a mechanistic understanding of how oncogenic events signal through distinct acetyltransferases to regulate cancer metabolism and suggest ACAT1 as an anti-cancer target.

Does Post-Transplant Maintenance Therapy With Tyrosine Kinase Inhibitors Improve Outcomes of Patients With High-Risk Philadelphia Chromosome-Positive Leukemia?

INTRODUCTION: The effect of post-transplant maintenance tyrosine kinase inhibitors (TKIs) on the outcomes of allogeneic hematopoietic stem cell transplantation in high-risk Philadelphia chromosome-positive (Ph(+)) leukemia remains unknown. PATIENTS AND METHODS: A retrospective analysis that included allograft recipients with accelerated phase and blast phase chronic myeloid leukemia or Ph(+) acute lymphoblastic leukemia who had received post-transplant maintenance TKI therapy from 2004 to 2014. RESULTS: A total of 26 patients, 9 with accelerated phase/blast phase CML and 17 with Ph(+) acute lymphoblastic leukemia, received maintenance post-transplant therapy with imatinib, dasatinib, nilotinib, or ponatinib. The TKI was selected according to the pretransplantation TKI response, anticipated toxicities, and ABL1 domain mutations, when present. Newer generation TKIs were initiated at a ≥ 50% dose reduction from the standard pretransplantation dosing to limit the toxicities and avoid therapy interruptions. TKIs were started a median of 100 days (range, 28-238 days) after transplantation and were administered for a median of 16 months (range, 8 days to 105 months). Eight patients discontinued therapy because of adverse events. With a median follow-up of 3.6 years (range, 4 months to 8.7 years), the 5-year relapse-free survival rate was 61%. All 3 patients who developed a relapse underwent successful salvage treatment and remained disease-free. The 5-year overall survival rate was 78%. CONCLUSION: Maintenance TKI therapy after transplantation is feasible and might reduce the incidence of relapses and improve outcomes after allogeneic hematopoietic stem cell transplantation for patients with high-risk Ph(+) leukemia.

6-Phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumour growth by inhibiting LKB1-AMPK signalling.

The oxidative pentose phosphate pathway (PPP) contributes to tumour growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumour growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between the oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signalling. Moreover, we identified and developed 6PGD inhibitors, physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumour growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.

Secondary Adult Acute Myeloid Leukemia: a Review of Our Evolving Understanding of a Complex Disease Process.

OPINION STATEMENT: Secondary AML (s-AML) encompasses AML evolving from myelodysplasia (AML-MDS) and treatment-related AML (t-AML) after exposure to chemotherapy, radiation, or environmental toxins. S-AML has traditionally been considered a devastating disease, affecting a vulnerable population of heavily pretreated, older adults. A limited understanding of disease pathogenesis/heterogeneity and lack of effective treatments have hampered overall improvements in patient outcomes. With the recent understanding that the secondary nature of sAML does not by itself incur a poor prognosis and incorporation of cytogenetics and molecular genetics into patient care and the advancement of treatment, including improved supportive care, novel chemotherapeutics agents, and nonmyeloablative conditioning regimens as part of allogeneic hematopoietic cell transplantation (HCT), modest gains in survival and quality of life are beginning to be seen among patients with s-AML.