A novel index using inflammatory markers improves the diagnosis of hemophagocytic lymphohistiocytosis in patients with hematologic malignancies

7563

Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may accompany hematologic malignancies (HM). The diagnosis of HLH in patients with HM (HM-HLH) is confounded by a number of factors: the most commonly used HLH-2004 diagnostic criteria are derived from studies in infants while the Hscore used in adults is not specific for HMs; moreover, most parameters in these scoring systems may reflect features of the underlying HM rather than HLH associated inflammation; and finally specific diagnostic cutoff values for laboratory abnormalities in HM-HLH have not been defined. We therefore conducted a study to optimize the HLH-2004 laboratory thresholds for the diagnosis of HM-HLH. Methods: A multi-center retrospective study in adult patients with HM in whom testing for HLH was performed. HM-HLH was defined as fulfillment of 5/8 HLH-2004 diagnostic criteria. We established the optimal diagnostic cutoff levels for HLH-2004 laboratory parameters using receiver operating curves (ROC) and combined the best performing parameters into a combined index, using binary logistic regression. We then created a clinical decision tree using a Classification and Regression Tree (CART) analysis with all available parameters, using cross validation. We also determined the prognostic value of our combined diagnostic tool. Results: 225 adults were analyzed (112 with HM-HLH per HLH-2004 and 113 with HM only). 35% of patients were evaluated for HLH routinely upon HM diagnosis. Soluble CD25 (sCD25) and ferritin best discriminated HM-HLH from HM, with an area under the curve (AUC) of 0.83 for each. ROC analysis demonstrated an optimal cutoff of > 4190 U/mL for sCD25 (sensitivity/specificity 91%/69%) and an optimal cutoff of > 2636 ng/ml for ferritin (sensitivity/specificity 64%/86%) for HM-HLH. We term the combination of elevated sCD25 and ferritin using optimized cutoff levels the ‘optimized HLH inflammatory’ (OHI) index. This OHI index was highly specific for the diagnosis of HM-HLH (specificity of 92%, sensitivity 79%). CART analysis demonstrated that OHI index positivity was sufficient to diagnose HM-HLH. In patients without a positive OHI index an Hscore > 168 and either splenomegaly or triglycerides > 279 ng/dL can still diagnose HM-HLH. By following this decision pathway, approximately 92% of patients were accurately classified based on HLH-2004. Furthermore, the OHI was better (odds ratio (OR) 7.9; 95% confidence interval (CI) 4.2-14.6) than Hscore >169 (OR 5.5; CI 3.9-9.6) and > 5/8 HLH-2004 (OR 5.3; CI 3-9.3) at predicting mortality at 1 year. Conclusions: The OHI index derived here is a simple tool that can accurately diagnose HLH and predict mortality in patients with hematologic malignancies. Some patients may not need full HLH workup before intervening with therapy that is HLH directed and not only malignancy directed.

Quizartinib with decitabine and venetoclax (triplet) is highly active in patients with FLT3-ITD mutated acute myeloid leukemia (AML)

e19019

Background: The outcomes in patients (pts) with newly diagnosed FLT3 mutated AML who are ineligible for intensive induction chemotherapy are poor. Added to a low intensity chemotherapy backbone, FLT3 inhibitors, such as midostaurin, sorafenib, and quizartinib, result in median OS of 8-17 months in the frontline (Gallogly ASH 2017, Ohanian AJH 2018, Swaminathan ASH 2017), and 4-8 months in relapsed/refractory (R/R) settings (Yilmaz JHO 2020, Ravandi Blood 2013). Quizartinib, a potent second generation FLT3 inhibitor demonstrated synergy with venetoclax (VEN) (a BCL-2 inhibitor) in AML cell lines and PDX models (Mali Haematologica 2020). We designed this study to evaluate the safety and efficacy of quizartinib, venetoclax, and decitabine combination in pts with R/R or newly diagnosed FLT3 mutated AML. Methods: Frontline cohort included pts who are ineligible for intensive induction chemotherapy, and R/R cohort included pts who received 5 or less prior treatments. All patients had a performance status of ECOG ≤2, adequate organ functions, and QTcF <450 msec prior to therapy. All pts underwent day 14 bone marrow, and venetoclax (400 mg/day) was put on hold in patients with bone marrow blasts ≤ 5% (or marrow aplasia). Those with day14 bone marrow blast >5% continued venetoclax for 21 days during cycle 1. All pts induced with 10 days of decitabine (20 mg/m2). In subsequent cycles, decitabine administered for 5 days. Quizartinib (30 or 40 mg/day) was administered daily continuously. Results: 21 pts were enrolled and 17 pts evaluable at the time of this report (4 are still within cycle 1). Of 13 pts with R/R AML (median 3 [range 1-5] prior therapies, 85% with ≥1 prior FLT3 inhibitor), 9 (69%) achieved CRc (2 CR, 7 CRi) with 4/9 and 5/9 responders FLT3-PCR and multicolor flow cytometry (MFC) negative, respectively. Thirty and 60-day mortality rates were 0% and 8%. Of 4 patients with newly diagnosed AML (median age 72), all achieved CRc (2 CR, 2 CRi) with 4/4 and 2/3 responders FLT3-PCR and MFC negative, respectively. 60-day mortality was 0% in the frontline cohort. No pts developed a dose limiting toxicity (DLT) with 30 mg/day quizartinib, however with the 40mg/day quizartinib 2 pts developed hematologic DLT (grade ≥3 neutropenia with a <5% cellular bone marrow lasting ≥42 days). Hence, quizartinib 30 mg/day dose was determined as recommended phase 2 dose for the triplet. Grade 3/5 non-hematologic toxicities in >2 pts included lung infections (N=9) and neutropenic fever (N=6). No QTcF prolongations >450 msec were noted. With a median follow-up of 7.2 months, the median OS was not reached in frontline cohort and was 7.1 months in R/R cohort. 2/4 and 5/9 responders underwent ASCT in frontline and R/R cohorts, respectively. All frontline pts were alive at the last follow-up; 3 were in CR and 1 relapsed disease. Of 9 responders in R/R cohort, 4 were alive (3 CR, 1 relapse) and 5 died (4 relapse, 1 CR). Conclusions: Decitabine + venetoclax + quizartinib is highly active in R/R FLT3-ITD mutated AML pts, with CRc rates of 69% and the median OS of 7.1 months. Accrual to the triplet continues and updated clinical and correlative data will be presented. Clinical trial information: NCT03661307.

Phase II study of the IDH2-inhibitor enasidenib in patients with high-risk IDH2-mutated myelodysplastic syndromes (MDS)

7010

Background: Isocitrate dehydrogenase 2 ( IDH2) mutations occur in 5% of patients (pts) with MDS. Enasidenib (ENA) is a selective oral inhibitor of the mutant IDH2 enzyme with single-agent activity in relapsed/refractory acute myeloid leukemia (AML). We report the results of the open label phase II study designed to evaluate the efficacy and tolerability of ENA, as monotherapy or in combination with azacitidine (AZA) in pts with higher-risk IDH2-mutated MDS (NCT03383575). Methods: Pts with higher-risk [Revised International Prognostic Scoring System risk > 3 or high molecular risk (HMR)] MDS/CMML or LB AML naïve to hypomethylating agents (HMA) received ENA100 mg orally daily for 28 d of each 28-d cycle + AZA 75 mg/m2 IV or SC on d 1-7 of each cycle (ENA+AZA), and pts with refractory or progressive MDS to prior HMA therapy received ENA alone (ENA), in 28-d cycles until unacceptable toxicity, relapse, transformation to AML, or progression. The primary endpoint was overall response rate (ORR) [complete remission (CR), marrow CR (mCR), partial remission (PR) and hematologic improvement (HI)]. Other endpoints include safety, and survival outcomes. Results: 48 pts received ENA+AZA (n = 26) or ENA (n = 22). The median age was 73 yrs (range, 46-83). Most pts (72%) had HMR: ASXL1 (39%), and RUNX1 (17%). Median number Tx cycles was 4 (2–32) in the ENA+AZA, and 7 (1–23) in the ENA arm. Common Tx-related grade 3–4 AEs in the ENA+AZA arm were neutropenia (64%), thrombocytopenia (28%), and anemia (8%); these occurred in 10%, 0%, and 5%, in the ENA arm. Grade 3–4 infections occurred in 32% (ENA+AZA) and 14% (ENA). IDH differentiation syndrome occurred in 3 pts (12%) in the ENA+AZA and 5 pts (24%) in the ENA arm. Two deaths occurred during the initial 60 d, both unrelated to study and due to COVID. In response-evaluable pts (n=46), ORR was 84% (n = 21/25; 24% CR + 8% PR+44% mCR+ 8% HI] in the treatment naïve ENA+AZA and 43% (n = 9/21; 24% CR+5%PR+5% mCR+10% HI) in the HMA failure ENA arm (Table). Most common reason for Tx discontinuation was disease progression (ENA+AZA 20%, ENA 33%).5 pts (20%) received HCT in the ENA+AZA and 1 (5%) in the ENA arm. 7 pts in the ENA+AZA and 5 in the ENA arm were ongoing at data cutoff (Dec 31, 2020). After a median follow up of 12.6 mo, median OS was 32.2 mo in the ENA+AZA and 21.3 mo in the ENA arm. Conclusions: ENA is well tolerated and shows promising efficacy in IDH2-mutated higher risk MDS. Follow up and accrual is ongoing to better define duration and biomarkers of response. Clinical trial information: NCT03383575. [Table: see text]

Activity of decitabine as maintenance therapy in core binding factor acute myeloid leukemia

7522

Background: Real-time quantitative (RTPCR) based minimal residual disease (MRD) monitoring provides prognostic information in core binding factor acute myeloid leukemia (CBF-AML). Earlier we reported on the activity of decitabine (DAC) as maintenance therapy in a smaller cohort of patients with CBF AML. Methods: We have summarized the results in patients (pts) with CBF who received DAC maintenance for persistent RTPCR positivity or because of inability to complete all planned consolidation in a fludarabine, GCSF, cytarabine (FLAG) based regimen. The planned number of DAC cycles was 12 but could be adjusted at the discretion of the treating physician based on RTPCR response. Serial RTPCR was obtained approximately every 2-3 months. Results: Thirty-four pts with CBF-AML [t(8;21)=14 and inv(16)=20] received DAC as maintenance. Eighteen pts (53%) completed a full course (7 cycles) of FLAG based regimen before DAC for persistent PCR positivity (group 1). Sixteen pts (47%) were switched to DAC as they did not complete planned consolidation (group 2). In group 2, 9 pts (56%) had negative PCR (group 2A) and 7 pts (46%) had positive PCR (group 2B) prior to starting DAC. Patient characteristics are summarized in table. The median follow up was 59.2 [15.4-107.2] and 32.47 [8.5-86.3] months for group 1 and 2, respectively. In Group 1 and group 2A only 1 patient each had relapse, while 5 pts (72%) from group 2B had relapse. All the patients in group 2B with relapse were at suboptimal RTPCR response (>0.1%). Conclusions: Our study shows DAC is an effective maintenance for CBF-AML pts who have persistent PCR positively after FLAG based induction consolidation and those unable to tolerate a full course, but have negative PCR. However patients with high levels of MRD persistence should be considered for stem cell transplant. [Table: see text]

Tolerability and efficacy of the first-in-class anti-CD47 antibody magrolimab combined with azacitidine in MDS and AML patients: Phase Ib results

7507

Background: Magrolimab (Hu5F9-G4) is an antibody blocking CD47, a macrophage immune checkpoint and don’t eat me signal on cancers. It induces tumor phagocytosis and eliminates leukemia stem cells. Azacitidine (AZA) synergizes with magrolimab by inducing eat me signals on leukemic cells, enhancing phagocytosis. We report Ph1b data including a potential MDS registration cohort. Methods: Magrolimab+AZA was given to untreated intermediate to very high risk IPSS-R MDS and intensive chemo unfit AML patients. A magrolimab priming/intrapatient dose escalation regimen (1-30 mg/kg QW, Q2W Cycle 3+) was used. AZA was dosed 75mg/m2 days 1-7. Efficacy was assessed by IWG 2006 (MDS) and ELN 2017 (AML) criteria. Results: 68 patients (39 MDS, 29 AML) with a median age of 72 were treated with magrolimab+AZA. 19% were intermediate cytogenetic risk with 68% poor risk (13% unknown). 27% were TP53 mutant. The combo was well-tolerated with safety similar to AZA alone. Common treatment-related AEs were anemia (38%), fatigue (21%), neutropenia (19%), thrombocytopenia (18%) and infusion reaction (16%). Treatment-related febrile neutropenia was 1.5%. Only 1 patient (1.5%) discontinued due to an AE. In RBC transfusion dependent patients, 58% of MDS and 64% of AML patients became transfusion independent. 30/33 (91%) efficacy evaluable MDS patients had an objective response (42% CR, 24% marrow CR (4/8 also with HI), 3% PR, 21% HI alone, 9% SD). MDS patient responses deepened on study, with a 56% CR rate in patients with ≥ 6 mo follow-up. In AML, 16/25 (64%) responded (40% CR, 16% CRi, 4% PR, 4% MFLS, 32% SD, 4% PD). In 12 TP53 mutant AML patients, 75% had a CR+CRi (42% CR, 33% CRi, 17% SD, 8% PD). Cytogenetic CR was seen in 35% and 50% of responding MDS and AML patients. 22% of MDS and 50% of AML patients with CR/CRi/marrow CR were MRD negative by flow cytometry. Median duration of response is not reached in either MDS or AML, including TP53 mutant AML, with a median follow-up of 5.8, 8.8 and 9.4 mos, respectively (range: 1.9 – 16.8 mos). 91% of MDS and 100% of AML responding patients are in response at 6 mos. The 6 mo overall survival estimate is 100% in MDS and 91% in TP53 mutant AML patients. Conclusions: Magrolimab is a macrophage targeting immunotherapy that with AZA is well tolerated with durable efficacy in MDS, AML, particularly TP53 mutant, a poor prognostic group. A potential registration single arm MDS cohort is ongoing (NCT03248479). ENHANCE, a randomized Ph3 MDS trial is planned. Additional patients/analyses will be reported. Funded by Forty Seven and CIRM. Clinical trial information: NCT03248479 .

Inotuzumab ozogamicin (INO) plus bosutinib (BOS) in R/R PH+ ALL or CML in lymphoid blast phase (CML LBP)

7512

Background: Pts with R/R Ph+ ALL and CML LBP have poor outcomes. INO is an anti-CD22 antibody drug conjugate approved for R/R ALL. BOS is a 2nd generation BCR-ABL TKI approved for CML. Methods: This was a phase I/II study of INO + BOS for R/R Ph+ ALL and CML LBP. Primary objective was to determine safety and the maximum tolerated dose (MTD) of the combination. Secondary objective was to assess efficacy. Pts with T315I mutation were excluded. Pts needed to have adequate organ function (Cr ≤2 gm/dL, total bilirubin ≤2 mg/dL, ALT & AST ≤3xULN). BOS was dosed once daily starting on cycle 1 day 1, and 3 dose levels were evaluated (300, 400, 500 mg) in a standard 3+3 design. INO was given IV weekly during cycle 1 (0.8 mg/m2 day 1; 0.5 mg/m2 day 8; 0.5 mg/m2 day 15). In responding pts, INO was subsequently administered at 1 mg/m2 once every 4 weeks for a total of 6 cycles. Results: Between June 2015 and December 2019 we enrolled 18 R/R pts (16 Ph+ ALL, 2 CML LBP). The median age was 62 yrs (range 19-74), median no. of prior therapies was 1 (range 1-5) and 9 pts had ABL kinase domain mutations at screening. There were no early deaths (<30 days). 3 pts were treated at BOS dose level 1; 6 pts at dose level 2; 9 pts at dose level 3. 1 pt had a DLT at dose level 2 - G3 skin rash, and 2 pts had a DLT at dose level 3 - both G3 skin rash. First 3 pts at dose level 3 did not receive ≥80% BOS doses during cycle 1 due to issues unrelated to adverse events (AE). As 2/6 DLT evaluable pts at dose level 3 had DLTs thus exceeding the MTD, the dose level 2 was identified as the MTD. Most frequent AE were diarrhea in 50%, rash in 50%, and nausea in 39%. Grade 3 AEs were rash (3), reversible ALT elevation (1) and hyponatremia (1). No pts had veno-occlusive disease. Pts have received a median of 3 cycles (range 1-8) with a median of 1 cycle to response (range 1-2). Responses are shown in Table. Median time to response was 1 months (mo, range 0.8-2.1), median time to negative MRD by flow cytometry (FCM) was 6.9 mo (range 3.4-18) and median time to complete molecular response (CMR) was 9.1 mo (range 3.4-18). After a median follow-up of 32 mo, the median overall survival was 15.4 mo and median event-free survival censored at stem-cell transplantation (SCT) was 6.1 mo. 6 pts underwent SCT, 8 pts relapsed, 10 pts are alive and 2 pts continue therapy. Conclusions: INO + BOS was well tolerated and showed promising activity in R/R Ph+ ALL and CML LBP. Clinical trial information: NCT02311998 . [Table: see text]

Geographic disparity of outcome in patients with cancer over decades: The surveillance, epidemiology, and end results

1574

Background: Improvements in prevention, early detection and therapy of cancer have decreased cancer related mortality yet health disparities continue to exist. We investigated the impact of such disparities in cancer survival. Methods: In the Surveillance, Epidemiology, and End Results, we identified 784,341 patients with cancer from 1990 to 2016 in Georgia; 68,493 in 1990-1999, 371,353 in 2000-2009, and 322,932 in 2010-2016. We assessed overall survival (OS) of patients with all cancers, chronic myeloid leukemia (CML), and lung cancer given the dramatic improvement in patient outcomes in CML since 2000 compared to the consistently poor outcome in lung cancer. We assessed distance from each county to the one National Cancer Institute-designated cancer center (NCI-CC) in Georgia. Results: The 5-year OS of patients with any cancer was 55% with median OS 80 months; the 5-y OS of each county ranged from 33% to 82% (interquartile range[IQR], 51%-65%)(P < 0.001). The improvement of OS was minimal over decades: 5-year OS was 52%, 55%, and 55% in 1990-1999, 2000-2009, and 2010-2016, respectively; the median was 69 months, 80 months, not reached, respectively (P < 0.001). In patients with lung cancer and CML, the 5-year OS was 15% and 52% with the median of 9 months and 67 months, respectively. The geographic difference between counties was relatively small and constant over time in patients with lung cancer, represented by the width in the range and IQR: range 5%-17%, IQR 9%-13%, median 13% in 1990-1999; range 2%-24%, IQR 10%-14%, median 14% in 2000-2009; and range 4%-24%, IQR 12%-17%, median 17% in 2010-2016. However, the geographic difference was more prominent in patients with CML and widened after introduction of modern therapy: range 20%-42%, IQR 26%-34%, median 32% in 1990-1999; range 14%-83%, IQR 38%-64%, median 53% in 2000-2009; and range 14%-80%, IQR 40%-57%, median 57% in 2010-2016. Multivariate Cox regression showed age (hazard ratio[HR],1.040;95% confidence interval[CI],1.039-1.040;P < 0.001), median county income (HR,0.919;95% CI,0.916-0.921;P < 0.001), African American (HR,1.021;95% CI,1.210-1.227;P < 0.001), and distance to NCI-CC (each 100 kilometers) (HR,1.021;95% CI,1.017-1.025;P < 0.001) as predictive factors. Conclusions: The disparity of cancer care exists between geographic locations. The geographic difference of survival seems more prominent when highly effective therapies are available.

A phase Ib/II study of the CD123-targeting antibody-drug conjugate IMGN632 as monotherapy or in combination with venetoclax and/or azacitidine for patients with CD123-positive acute myeloid leukemia

TPS7564

Background: Overexpression of CD123 is characteristic of a number of hematological malignancies, including acute myeloid leukemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN). IMGN632 is a CD123-targeting antibody-drug conjugate (ADC) with a novel anti-CD123 antibody coupled to a unique DNA-alkylating payload of the recently developed IGN (indolinobenzodiazepine pseudodimer) class of payloads. In preclinical models of AML, IMGN632 exhibited potent anti-leukemia activity, with a wide therapeutic index. Confirming preclinical expectations, encouraging single-agent activity and favorable tolerability have emerged for IMGN632 in the ongoing Phase I trial in patients with CD123-positive AML (ASH 2019, NCT03386513). Preclinical data from AML xenograft models have demonstrated synergy in IMGN632 combinations with azacitidine and venetoclax (EHA 2019), supporting the exploration of these combinations in AML patients. Methods: This Phase Ib/II study is designed to determine the safety, tolerability, and preliminary anti-leukemia activity of IMGN632 when administered in combination with azacitidine and/or venetoclax to patients with relapsed and frontline CD123-positive AML, and the single-agent activity of IMGN632 in patients with minimal residual disease (MRD)-positive AML after frontline treatment. Study Design: Adult patients with CD123-positive relapsed or refractory AML, who are deemed appropriate for experimental therapy, are eligible to enroll as part of the dose escalation phase. Key exclusion criteria for all regimens include active central nervous system disease, and history of sinusoidal obstruction syndrome/venous occlusive disease of the liver. Three combination regimens are being evaluated: Regimen A, IMGN632 plus azacitidine (632+AZA); Regimen B, IMGN632 plus venetoclax (632+VEN); and Regimen C, IMGN632 plus azacitidine and venetoclax (632+AZA+VEN). For each regimen, a Phase Ib dose escalation cohort will determine the recommended Phase II dose (RP2D) of IMGN632 for the specific combination. This will be followed by a Phase II dose expansion stage to further characterize the safety profile and assess antileukemia activity in frontline or relapsed AML patients, depending on combination regimen. In addition, IMGN632 monotherapy is being explored in expansion cohorts of MRD-positive patients to assess conversion rate from MRD+ to MRD-, in fit and unfit AML subpopulations. Clinical trial information: NCT04086264 .

A phase I/II study of IMGN632, a novel CD123-targeting antibody-drug conjugate, in patients with relapsed/refractory acute myeloid leukemia, blastic plasmacytoid dendritic cell neoplasm, and other CD123-positive hematologic malignancies

TPS7563

Background: Overexpression of CD123 occurs in multiple hematological malignancies, including acute myeloid leukemia (AML), blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute lymphoblastic leukemia (ALL) and others, thus making this antigen an attractive target for the development of new therapeutics. IMGN632 is a CD123-targeting antibody-drug conjugate (ADC) comprising a novel anti-CD123 antibody coupled, via a peptide linker, to a unique DNA-alkylating cytotoxic payload of the recently developed IGN (indolinobenzodiazepine pseudodimer) class. Preclinically, IMGN632 has demonstrated potent activity against AML, BPDCN and ALL models, with a wide therapeutic index in animal models, as well as a 150-fold differential cytotoxicity in AML patient samples compared to normal hematopoietic progenitors (PMIDs: 29661755, 30361418). Remarkable sensitivity of BPDCN patient derived xenografts to IMGN632 has been demonstrated (Blood 2018 132:3956). Methods: This Phase I/II study comprises a dose escalation phase designed to establish the recommended phase II dose (RP2D) for IMGN632, as well as dose expansion cohorts to further explore the safety and preliminary anti-leukemia activity of IMGN632. Expansion cohorts were designed to evaluate the following patient populations: adult patients with relapsed or refractory BPDCN or patients with untreated BPDCN who are inappropriate for available therapies, patients with relapsed or refractory AML, or with other CD123+ relapsed or refractory hematologic malignancies including ALL. Inclusion criteria include up to four prior lines of therapy which may include transplant. Patients with active central nervous system disease, history of veno-occlusive disease of the liver, or history of grade IV capillary leak syndrome or non-cardiac grade IV edema are ineligible. Expansion cohorts for unfit frontline and relapsed/refractory BPDCN, and relapsed/refractory ALL continue to enroll at the RP2D (0.045 mg/kg Q3W). Clinical trial information: NCT03386513 .

Ten-day decitabine with venetoclax (DEC10-VEN) in AML and high-risk (HR) MDS

7519

Background: VEN-based low intensity regimens have shown promise in older pts with newly diagnosed (ND) AML. We hypothesized that adding VEN to 10-day (d) DEC may improve outcomes in AML and HR MDS. Methods: Pts received VEN 400 mg daily or equivalent with DEC 20 mg/m2 for 10d every 4-8 weeks for induction and DEC 5d with VEN for consolidation after CR/CRi. If cycle 1 day 21 bone marrow showed ≤5% blasts, VEN was held to enable count recovery. VEN duration could be further reduced for myelosuppression. FLT3 and IDH inhibitors were allowed for applicable pts. All pts received tumor lysis syndrome (TLS) prophylaxis. Primary objective was overall response rate (ORR). Secondary objectives were safety and overall survival (OS). Data cut-off date was February 6, 2020. Results: Between January 2018 and December 2019 we enrolled 184 pts with ND AML (>60 yrs), untreated secondary AML (sAML), treated sAML, relapsed/refractory (R/R) AML and HR MDS (Table). 58% pts were ≥70 yrs, 30% pts had ECOG PS ≥2, 67% pts had ELN adverse risk AML. Previously treated pts (n=96) had received a median of 1 prior therapy (range 1-8) including HMA (62), intensive chemotherapy (49) and stem cell transplantation (SCT, 27). 30d mortality was 3.3% and 60d mortality was 7.6%. 30d mortality in ND AML was 1.4%. Most common G3/4 adverse events were infections with G3/4 neutropenia (46%), febrile neutropenia (28%), infections with ANC ≥1x109/L (6%) and TLS (3%). Outcomes are shown in Table. 25 pts (14%) proceeded to SCT including treatment naive AML (ND+ untreated sAML, 12), previously treated AML (treated sAML + R/R, 11) and HR MDS (2). 100d post-SCT mortality was 4%. Median OS in treatment naïve AML pts undergoing SCT was not reached (1yr OS 100%) and for previously treated AML pts was 22.1 months (mo). After a median follow up of 15 mos, 25% PTS continue therapy. Additional analyses by molecular subgroups will be presented. Conclusions: DEC10-VEN is safe and highly effective in ND AML and can serve as an effective bridge to SCT in previously treated pts. Trial continues to accrue (NCT03404193). Clinical trial information: NCT03404193 . [Table: see text]

Venetoclax (Ven) added to intensive chemo with cladribine, idarubicin, and AraC (CLIA) achieves high rates of durable complete remission with low rates of measurable residual disease (MRD) in pts with newly diagnosed acute myeloid leukemia (AML)

7539

Background: Ven is a BCL2 inhibitor that is approved in combination with lower intensity therapy for pts with newly diagnosed AML who are ineligible for intensive chemo. We previously reported the safety and efficacy of cladribine and araC with idarubicin in young and fit pts with AML. Here, we studied the combination of ven with the intensive CLIA regimen in newly diagnosed AML. Methods: Pts < 65 yrs with newly diagnosed FLT3-wildtype AML were enrolled. Induction was cladribine 5 mg/m2 IV on D 1-5, followed by ara-C 1.5 g/m2 IV on D 1-5, idarubicin 10 mg/m2 IV D 1-3, and ven at an effective dose of 400mg PO on D2-8. There was no ramp up for ven and dose modifications for CYP3A4 inhibitors were made. Consolidation consisted of up to 5 more cycles of CLIA+Ven. All pts underwent baseline next generation sequencing and MRD testing by multiparameter flow cytometry at the time of response. Results: 18 pts are enrolled, with a median age of 50 yrs (range, 18-64). Baseline pt characteristics are in Table. 16 pts were evaluable for response and 2 are too early. 14 of 16 pts (88%) achieved a remission, including 10 (63%) complete remission (CR) and 4 (25%) CR with incomplete count recovery (CRi). The median time to response was 1 cycle and the median number of cycles given was 2 (1-5). 10 of the 14 responders (71%) had undetectable MRD at the time of remission. Both nonresponding pts had a complex karyotype and 1 had a TP53 mutation. With a median follow up of 4.5 months (0.2 – 11.2), none of the responding pts have relapsed. 8 of the 14 responders (57%) have received allogeneic stem cell transplant. The median survival has not been reached; the 6-month OS and RFS are 90% and 100%, respectively. Treatment was well tolerated, with 0% 4-week mortality. The median days to ANC ≥ 1 and Platelets ≥ 100 were 30 (19-49) and 26 (18-39), respectively. Tumor lysis syndrome was not seen. The most common adverse events were neutropenic fever, pneumonia, nausea, and liver transaminitis. Conclusions: The addition of ven to CLIA was safe and effective in newly diagnosed pts with AML. The combination was not associated with early mortality or prolonged myelosuppression, but did result in high rates of durable MRD negative remissions. Clinical trial information: NCT02115295 . [Table: see text]

Phase Ib/II study of the IDH1-mutant inhibitor ivosidenib with the BCL2 inhibitor venetoclax +/- azacitidine in IDH1-mutated hematologic malignancies

7500

Background: Mutations in the isocitrate dehydrogenase-1 gene ( IDH1) result in myeloid differentiation arrest and accumulation of the oncometabolite 2-hydroxyglutarate (2-HG), promoting leukemogenesis. We report a primary safety and efficacy analysis of the IDH1 inhibitor ivosidenib (IVO; 500 mg PO daily D15-continous) combined with venetoclax (VEN; D1-14 per 28-day cycle), with and without azacitidine (AZA; 75mg/m2 D1-7). Methods: Eligible patients age ≥18 with IDH1 mutated myeloid malignancies (high-risk MDS and AML) enrolled into one of three successive cohorts (Cohort 1: IVO+VEN 400 mg, Cohort 2: IVO+VEN 800 mg, Cohort 3: IVO+VEN 400 mg+AZA). Primary endpoints include safety and tolerability and overall response rate (ORR) by revised IWG criteria. Key secondary endpoints include survival endpoints and PK correlates. Results: 19 patients (median age 68) enrolled, 17 with AML: 9 relapsed/refractory AML (R/R; median 1 prior line of therapy), 5 treatment naïve AML, and 3 HMA-failure MDS with secondary AML. Two patients had high-risk MDS. ELN risk was favorable, intermediate, and adverse risk in 37%, 15%, and 47%. Co-mutations included NPM1 (37%), chromatin-spliceosome (32%), methylation (16%), and RAS pathway (21%). Adverse events of special interest included IDH differentiation syndrome (n=4, grade > 3 in 1) and tumor lysis syndrome (TLS; n=2), including one grade 3 TLS event in a NPM1+ patient (successfully managed without hemodialysis). In evaluable patients (n=18), composite complete remission (CRc: CR+CRi+CRh) rates were 78% overall (treatment naive: 100%, R/R: 75%), and 67%, 100%, and 67% by cohort (median time to best response: 2 months). 7 (50%) patients achieving CRc were also MRD negative by flow cytometry. 1 patient had HI without CR/CRi and 1 had a MLFS. 9 (50%) patients remain on study, 3 (17%) proceeded to SCT in CR, 2 were non-responders, and 5 (22%) experienced progressive disease following CRc occurring after a median of 3 months. After a median follow up of 3.5 months, median OS was not reached in treatment naïve patients, and 9.7 months in R/R patients. Conclusions: IVO+VEN +AZA therapy is well tolerated and highly effective for patients with IDH1 mutated AML. Follow up and accrual is ongoing to better define duration and biomarkers of response. Clinical trial information: NCT03471260 . [Table: see text]

Activity of venetoclax-based therapy in TP53-mutated acute myeloid leukemia

7034

Background: Mutations in TP53 are associated with low response rates to standard therapy and poor outcomes in patients (pts) with acute myeloid leukemia (AML). Combination therapy with the BCL2 inhibitor venetoclax (VEN) has emerged as an effective treatment option for pts with AML. Methods: We reviewed pts with TP53-mutated AML treated with VEN-based therapy between 2014-2018. Mutation testing was performed using a whole-exome next-generation sequencing panel. We analyzed the characteristics of these pts, responses to therapy, and outcomes. Results: Sixty nine pts with TP53-mutated AML treated with VEN were identified, 36 (52%) in frontline & 33 (48%) in the salvage (R/R) setting (Table). The median follow up was 4.5 [0.5 - 48.5] and 8 [1 - 46.5] months for frontline & R/R pts, respectively. Karyotype was complex in 32 (88%) and 29 (88%) pts in the frontline & R/R cohorts, respectively. In the R/R cohort, the number of median prior treatments was 2 [0 – 8]. VEN was given in combination with: 1) Hypomethylating agents (HMA) (87%), 2) FLAG-Ida (3%), 3) Low dose Ara-C (4%), or 4) CPX-351 (6%). The overall response rate (ORR) was 47% & 24% in frontline and R/R pts, respectively. All 6 pts with negative minimal residual disease (MRD) achieved complete cytogenetic response after taking VEN % remain in complete remission (CR) with a median of 3.4 [1.7-4.7] months. Two pts (both R/R) underwent allogeneic stem cell transplantation. Conclusions: VEN based therapy was associated with similar ORR, but higher CR rates in TP53 mutated AML compared with HMAs alone. Larger studies with longer follow up are needed to determine the role of VEN-based therapy in this difficult subset. Patient characteristics and outcome. [Table: see text]

A phase I study of milademetan in combination with quizartinib in patients (pts) with newly diagnosed (ND) or relapsed/refractory (R/R) FLT3-ITD acute myeloid leukemia (AML)

TPS7067

Background: Fms -like tyrosine kinase 3 internal tandem duplication ( FLT3-ITD) mutations occur in ≈ 25% of pts with AML and are associated with poor prognosis. Quizartinib is a highly potent, selective, next-generation type II FLT3 inhibitor. In the phase 3 QuANTUM-R trial, quizartinib prolonged overall survival vs salvage chemotherapy in pts with R/R FLT3-ITD AML. MDM2 downregulates the p53 tumor suppressor and is upregulated in pts with AML. Targeting MDM2 may restore p53 activity in pts with wild-type p53 AML. Milademetan, a novel and specific MDM2 inhibitor, showed activity in an ongoing phase 1 trial in pts with AML or myelodysplastic syndromes (MDS). Preclinical studies have shown that quizartinib plus milademetan may act synergistically to target FLT3-ITD and restore p53 activity in FLT3-ITD/ TP53 wild-type AML [Andreeff et al. ASH 2018, abstract 2720]. Methods: This open-label phase 1 study (NCT03552029) has 2 parts: dose escalation (part 1) followed by dose expansion (part 2), with 2 planned cohorts. Key inclusion criteria include FLT3-ITD AML (primary or secondary to MDS) and adequate renal, hepatic, and clotting functions. Key exclusion criteria include acute promyelocytic leukemia, prior treatment with a MDM2 inhibitor, QTcF interval > 450 ms, significant cardiovascular disease, and unresolved toxicities from prior therapies. Dose escalation and expansion cohort 1 includes R/R pts. Expansion cohort 2 includes ND pts unfit for intensive chemotherapy. During dose escalation, quizartinib will be administered once daily in 28-day cycles, with 3 proposed levels (30, 40, and 60 mg). Milademetan will be administered on days 1-14 of each 28-day cycle, with 3 proposed levels (90, 120, and 160 mg). The quizartinib dose will be escalated first, followed by the milademetan dose with no simultaneous escalation, guided by modified continual reassessment with overdose control. Primary objectives are safety and tolerability, optimum dosing schedule, maximum tolerated dose, recommended dosing for the expansion cohort, and phase 2 dosing. Secondary objectives are pharmacokinetics and preliminary efficacy. This study is recruiting. Clinical trial information: NCT03552029.

Granulocyte transfusions in patients with skin and soft tissues infections and leukemia: Are they useful?

7022

Background: Granulocyte transfusions (GTX) have been proposed to improve clinical outcome of neutropenic patients (pts) with serious infections. We evaluated the impact of unirradiated GTX in pts with skin and soft tissue infections (SSTI) and leukemia. Methods: We did a retrospective analysis of pts with leukemia and SSTI that received GTX from 2014 to 2018. We analyzed infection outcome and changes in ANC after GTX. Donors were mobilized using G-CSF plus oral dexamethasone 12 hours prior to apheresis. Results: Twenty-seven pts received 141 GTX for 33 SSTI. Transfusions were unirradiated, except for 10 (7%) radiated units administered due to availability. Twenty pts were male (74%); median age was 59 yrs (20–83 yrs). Hematologic diagnoses included AML (23, 70%), MDS (3, 9%), ALL (3, 9%), CLL (2, 6%), CML (1, 3%), and MF (1, 3%). In 24 (73%) SSTI, pts had a baseline ANC<0.5 x109/L, 3 (9%) had ANC between 0.51x109L to 0.99 x 109L, and 6 (18%) with ANC >1 x109/L. After GTX, ANC increased in 99 (70%) cases by a median of 0.7 x 109/L (0.02 to 10.03) with a median peak time of 9 hrs (4 to114 hrs), with a median time from GTX to first drop of 34 hrs (10 to 136 hrs). ANC decreased in 27 (19%) (by a median -0.5 x 109/L,-0.02 to -2.41). There was no change of ANC in 15 (11%). Improvement was determined by reduction in fever and inflammation, or resolution of SSTI 7 days after first GTX. Twenty-seven (82%) episodes improved. In those improved, ANC remained <1.5x109/L in 15 (56%) episodes after last GTX and after improvement. Main adverse reactions were fever in 21% (29), and respiratory complications in 6% (9) (pulmonary effusion, respiratory distress and acute hypoxemia). One pt (3%) required intubation. There was no transfusion-related GVHD. Cumulative survival from first GTX on each SSTI by Kaplan-Meier Survival was 82% (8) at 30 days, 49% (17) at 90 days, 41% (17) at 180 days, and 24% (12) at 360 days. Eight of this pts died of infections, 4 of which were SSTI described on this paper. Conclusions: GTX have a beneficial effect on clinical improvement in patients with SSTI and underlying hematological malignancies and severe neutropenia. It can be safely administered without GVHD. Further prospective studies are warranted.

Association of smoking with poor risk ELN 2017, cytogenetics/molecular profile, and survival outcomes in acute myeloid leukemia

7002

Background: Smoking increases the relative risk of AML by 40% and 25% in active and former smokers, respectively, compared with non-smokers (Fircanis et al., 2014). While the relationship of smoking with AML development is recognized, whether smoking impacts underling AML biology and clinical outcome remains ill-defined. Methods: Newly diagnosed, treatment naïve AML pts seen at MDACC between 2012 and 2017 with available smoking history were evaluated, along with baseline parameters, co-occurring mutations, cytogenetics and clinical outcome. Results: We identified 858 pts [486 (57%) male; median age 67 yrs (14-97)], representing 535 (62%) treatment naïve and 323 (38%) salvage pts. Smoking status was recorded as smokers (active = 39 pt, former = 380 pt), versus never smoker (439 pt). In tx naïve group, smoking is associated with lower remission rates (OR 0.63, 95% CI 0.43-0.94, p = 0.02) and inferior OS (HR = 1.6, 95% CI 1.27-2.02, p < 0.001). Smoking status was not significant in multivariate analysis including AML biologic characteristics and ELN 2017 risk stratification. Therefore we postulated that worse OS may be driven by smoking associated AML biology rather than smoking associated comorbidities. Indeed, in univariate analysis smoking was associated with poor ELN risk (p = 0.015), complex karyotype (p = 0.0002), and TP53 mutation (p = 0.0235) while negatively associated with NPM1 (p = 0.018), FLT3-ITD (p = 0.032) and GATA2 (p = 0.0497). Age was a significant cofounder between smokers vs non-smoker ( < 0.0001). After controlling for age, significance was retained for ELN risk, complex karyotype and GATA2 at p = 0.0454, p = 0.0006, p = 0.048 respectively, while significance was lost for NPM1 (p = 0.079), FLT3-ITD (p = 0.1) and TP53 (p = 0.084). In analysis of young pts ( < 60 yr), smoking is positively associated with complex karyotype (p = 0.0042) and TP53 (p = 0.0289), and negatively associated with RUNX1 (p = 0.0143) and IDH2 (p = 0.0357). Conclusions: We report the largest analysis of smoking status and impact on molecular, cytogenetics, and AML clinical outcomes. Smoking history is associated with poorer risk molecular and cytogenetics, lower response rate and shorter survival in treatment naïve patients.

Venetoclax (VEN) and tyrosine kinase inhibitor (TKI) combinations in Philadelphia chromosome-positive (Ph+) acute myeloid leukemia (AML) and chronic myeloid leukemia myeloid blast phase (CML MBP)

e18515

Background: Ph+ AML and CML MBP have poor outcomes. VEN synergizes with BCR-ABL TKIs in vitro and may eradicate Ph+ leukemic stem cells. However, the clinical activity of VEN+TKI regimens is unknown. Methods: We conducted a retrospective study on patients (pts) with Ph+ AML and CML MBP who received regimens with VEN+TKI at our institution. Results: We identified 6 pts with relapsed/refractory (R/R) Ph+ AML and 7 with CML MBP (2 transformed from chronic phase, 5 R/R). 10 pts (77%) were refractory to prior therapy and 3 (23%) had relapsed disease. Pt characteristics are shown in the Table. 5 AML pts (83%) had complex cytogenetics. Pts with CML MBP had received a median of 2 prior TKIs (range 1-3). 7 pts received decitabine-based combinations and 6 pts received intensive chemotherapy in combination with VEN+TKI. TKIs included ponatinib (n=7), dasatinib (n=4), bosutinib (n=1) and nilotinib (n=1). Among 12 evaluable pts, the overall response rate (CR + CRi + MLFS) was 50% (Table). In addition, 1 pt with AML developed aplastic marrow, underwent stem cell transplantation, and is still alive. Pts with CR/CRi vs. those without CR/CRi had higher median number of Ph+ metaphases (100% vs. 32%, p<0.01) and higher baseline BCR-ABL1 PCR (100% vs. 0.5% p=0.01). The only AML pt who achieved CR/CRi had 100% Ph+ metaphases. After a median follow-up of 10.9 months (mo), 5 pts are alive (1 AML, 4 CML MBP). The median overall survival for pts with AML and CML MBP were 2 mo and not reached, respectively. The median relapse-free survival was 8.2 mo. Conclusions: VEN+TKI combinations show encouraging activity in pre-treated, advanced Ph+ leukemias, particularly CML MBP. Clonal burden of Ph+ cells correlated with response. Prospective trials are needed to evaluate VEN+TKI combinations in Ph+ leukemias. Pt characteristics and outcomes (n/N [%] / median [range]). [Table: see text]

IL2-STAT5 immune signatures to predict responses to PD-1 inhibition and azacitidine treatment in acute myeloid leukemia (AML): A subset analysis of a phase 2 study

7041

Background: Combining PD-1/PD-L1 blockade with hypomethylating agents (HMA) shows encouraging preliminary efficacy in AML, but immune features predictive of response are lacking. Methods: We treated 11 relapsed/refractory (R/R) AML patients with azacitidine (AZA) and nivolumab (Nivo) in a phase 2 clinical trial ( Daver N et al Cancer Discovery 2018). Patient characteristics: median (med) age 65 years (47-73), 63% adverse cytogenetics, 27% TP53 mutated. Pretreatment bone marrow aspirates had immune-phenotypic 17-color flow analysis and NanoString RNA quantification of 1469 immune-relevant genes. Results were correlated with clinical, pathological and molecular data. Results: The median courses of AZA+Nivo administered was 3 (range 1-17). The CR/CRi rate was 45% (including 2 CR, 1 CRi, 1 CRN and 1 CRP), with a median time to response of 1.8 months (range 0.8-4.9 months). The median overall survival was 13 months with 27% patients alive at 1 year. We found significant positive correlations between proportions of T-effector cells at baseline, and CD3+, CD8+, and T-regulatory cells at end of cycle (EOC) 1 (r > 0.75, p < 0.01 for all). At EOC2, these correlations were no longer significant. However, there was a significant positive correlation between T-effector cells at baseline and T-regulatory cells (r = 1, p < 0.001) at EOC4. Using NanoString analysis, we found 105 differentially expressed genes (fold change = 1.5, p < 0.05) between responders (5/11) and non-responders (6/11) at pretreatment. IL2-STAT5, TP53 and TNF Hallmark pathways and immune response from GO gene sets were highly enriched (q < 5x10-4) in responders. We then utilized z-score distribution analysis to quantify the degree of activation of known immunologic pathways. We found that signatures highly specific to neutrophils, NK cells, T-cells and eosinophils were significantly (p < 0.05) upregulated in patients with CR compared to non-responders at pretreatment. Conclusions: Our data demonstrates that a signature suggestive of lymphocyte activation in the pretreatment BM may be associated with augmented clinical response to PD-1 based therapies. Similar underlying pathways that have consistently predicted for responses to PD-1 inhibition in solid cancers, primarily IL2-STAT5 genes, may have predictive relevance in AML. Such pretreatment flow and NanoString signatures may help select AML patients most likely to benefit from PD-1 blockade plus HMA, further enhancing the benefit-risk ratio with such therapies.

Allogeneic stem cell transplantation (AlloSCT) for patients (pts) with acute leukemia following venetoclax-based therapy

7047

Background: BCL-2 inhibitor Ven has shown a promising benefit in pts with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). There is paucity of information about the safety and efficacy of alloSCT post Ven. Methods: We conducted a retrospective analysis of 35 AML/ALL pts who received alloSCT following Ven-based therapies between 2013-2018 at MDA. Results: Median age at alloSCT was 60 years and 15 (43%) pts had an age-adjusted HCT-CI score ≥ 4. Disease diagnosis – AML (n = 31; 89%), ALL (n = 4; 11%). Disease status at transplant was CR1 (n = 17; 49%), CR2/CR3 (n = 9; 26%) or refractory (n = 9; 26%). 20/26 (77%) CR pts were MRD-negative. Median # of prior therapies was 2 (range 1-7) and 4 (11%) pts had failed a prior alloSCT. AML pts were classified by ELN 2017 criteria to have favorable, intermediate and adverse risks in 16%, 23% and 61% respectively. Ven was provided in combination of hypomethylating agents (HMA) or other chemotherapies in 26 (74%) and 9 (26%) pts, respectively. Among pts treated with Ven + HMA, some also received IDH1/2 inhibitors (n = 7, 20%), FLT3 inhibitors (n = 4; 11%) or anti-PD1 (n = 3, 9%). Median duration of Ven-based treatment was 2 months (range 0.5- 4.6). Ven was discontinued in 6 (17%) pts due to adverse events (n = 4) or progression (n = 2); the remaining pts (83%) continued their Ven-therapy as a bridge to alloSCT. The median time from last Ven dose and transplant was 26 days. Conditioning regimens were melphalan-based reduced intensity (n = 26, 74%), or busulfan-based myeloablative regimens (n = 9; 26%). Donor source was matched -unrelated (n = 14, 40%), -related (n = 9; 26%) or haplo- (n = 12; 34%). GVHD prophylaxis consisted of tacrolimus with either PT-Cy in 25 (71%) pts or methotrexate in 10 (29%) pts. All pts engrafted (median day 30 donor cells = 100%). Median days to ANC > 500 and platelets > 20K was 15.5 and 22.5, respectively. With a median follow up of 5.7 months (range 0.7-15.4), the 1-year rates of OS, PFS, and NRM were 71%, 63% and 3% respectively. CI of acute grade 2-4 and 3-4 GVHD were 26% and 3% respectively. Four pts died: 3 because of disease relapse and 1 of infection. Conclusions: AlloSCT is a safe and feasible consolidation treatment option in acute leukemia pts who were pre- treated with Ven, without excessive risk of NRM or acute GVHD. Larger prospective studies are required to validate our observations.

Clinical value of event-free survival (EFS) in acute myeloid leukemia (AML)

e18513

Background: EFS is not considered a robust end-point for AML trials. We hypothesized that rather than a surrogate for overall survival (OS), improvement in EFS may be valuable due to patients (pts) staying in remission and thus decreasing health care utilization (HCU). Methods: In this retrospective study we identified AML pts treated on frontline therapy trials at our institute from 2003-2013 with EFS ≥2 months (mo) and OS of 12-36 mo. We captured the amount of HCU from diagnosis till death, including number of clinic and emergency room (ER) visits, hospitalizations, consultations, blood product transfusions, invasive procedures, laboratory and imaging studies. Linear regression and product-moment correlation were used to determine the relation between these parameters and EFS. Results: Among 337 pts meeting inclusion criteria, the median age was 65 years, 30% had adverse risk AML, 47% received intensive chemotherapy (IC) and 27% received hypomethylating agents (HMA). The median EFS was 10.8 mo. Increasing EFS led to statistically significant decline in HCU for all patients regardless of OS and the correlations were stronger for pts achieving a complete remission (CR, Table). These observations held true across European LeukemiaNet risk groups, younger and older pts, and those receiving IC, HMA, and non-IC, with or without other agents. Conclusions: In newly diagnosed AML, improvement in EFS is correlated with decrease in all HCU irrespective of OS duration. [Table: see text]