Dorsal Column Myelopathy Following Intrathecal Chemotherapy for Leukemia

PURPOSE/OBJECTIVE(S)

Intrathecal (IT) methotrexate (Mtx) and/or cytarabine (AraC) improve CNS disease control in patients (pts) with hematologic malignancies. There are increasing number of case reports of irreversible, primarily dorsal column myelopathy in pts treated with IT chemotherapy. By describing the largest case series of myelopathy following IT chemotherapy, we aim to raise awareness about this devastating albeit rare complication.

MATERIALS/METHODS

We retrospectively reviewed 25 pts with leukemia who developed paraplegia following IT chemotherapy between 2/2006 and 9/2021. Clinical/treatment characteristics, response, and toxicity were extracted from the medical records.

RESULTS

Seventeen pts (68%) were male, 16 had B-cell ALL (64%), 4 had AML (16%), 2 had CML (8%), 2 had T-ALL (8%), and 1 had BPDCN (4%). The median age at diagnosis was 38 years (IQR 30-59). All pts required systemic salvage treatment after induction chemotherapy with a median number of 3 regimens received (IQR 2-5.5). In total, the median number of IT treatments was 19 per pt (IQR 14-27). Most pts (84%, n = 21) received single agent IT Mtx alternating with single agent AraC. Fifteen pts (60%) received triple IT therapy with a median of 3 treatments (IQR 0-8). Prior to the onset of myelopathy, 10 pts (40%) received allogeneic SCT and 9 pts (36%) were treated with radiation therapy. Median follow-up from diagnosis was 1.9 yrs (IQR 1.3-4.1). Myelopathy was progressive and irreversible in all pts (n = 25); 84% (n = 21) experienced sensory loss, and all pts had extremity weakness. Symptoms were ascending in 11 pts (44%) and descending in 4 pts (16%). Irreversible bowel/bladder incontinence developed in 12 pts (48%). CSF analysis at the time of symptom onset was negative for leukemia cells in most pts (n = 21, 84%) and showed malignant cells in 4 pts (16%). CSF studies showed elevated protein in 21 pts (84%). Myelin basic protein was elevated in all 13 assessed pts. On T2 weighted spinal MRI, all pts had enhancement of the dorsal columns, including 80% of pts with this dorsal column abnormality reported at the time of the study and 20% of pts (n = 5) with the dorsal enhancement noted retrospectively. Due to concern for occult disease, 20 pts (80%) received additional CNS-directed therapy after symptom onset. Twenty-two pts (88%) died at last follow-up. The time between neurological symptom onset and death was a median 3.5 months (IQR 2.6 and 5). Three pts (12%) are alive with paraplegia at a median of 4.4 years from symptom onset.

CONCLUSION

Dorsal column myelopathy is a rare but devastating condition that can occur after IT chemotherapy in heavily pre-treated leukemia pts. T2 weighted spinal MRI can be helpful in the evaluation of pts that present with unexplained weakness and sensory changes. We recommend delaying additional CNS-directed therapy until work-up to rule out alternative etiologies is complete. Future strategies are desperately needed to address this irreversible treatment complication.

Impact of induction approach on post-stem cell transplant (SCT) outcomes in older adults with newly diagnosed acute myeloid leukemia (AML)

7038

Background: The optimal induction regimen for older patients (pts) with AML who are eligible for SCT is not well-established. Methods: This is a retrospective analysis of 127 pts age ≥60 years with newly diagnosed AML who underwent allogeneic SCT in first remission between 9/2012 and 7/2021 at our institution. Pts with previously treated secondary AML were excluded. Pts were divided according to induction therapy received: intensive chemotherapy (IC) (n = 44), lower-intensity therapy (LIT) without venetoclax (VEN) (n = 36), and LIT with VEN (n = 47). We compared overall survival (OS), relapse-free survival (RFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) according to the induction regimen received. Results: Pts who received IC were younger than those who received LIT with or without VEN (median age: 63 vs. 68 years; P < 0.0001) and were more likely to have an ECOG performance status of 0 at time of AML diagnosis (34% vs. 14%; P = 0.02). Cytomolecular risk was well-balanced between the 3 arms; the rates of adverse cytomolecular features in the IC, LIT without VEN and LIT with VEN groups were 43%, 50%, and 55%, respectively. Donor sources and degree of HLA matching were similar in the 3 groups. Most pts (92%) in the LIT with VEN group received reduced-intensity conditioning prior to SCT, compared with 54% and 58% in the IC and LIT without VEN groups, respectively. The majority of pts achieved CR/CRi prior to SCT (IC cohort:100%, LIT without VEN: 94%, LIT with VEN: 92%); the rest had MLFS as best response. The rate of measurable residual disease (MRD) negativity by flow cytometry prior to SCT was higher in the LIT with VEN group (69%), compared with IC (58%) and LIT without VEN (49%) (P = 0.14). The median number of cycles of chemotherapy prior to SCT was 3 in all groups. The median post-SCT follow-up was 37 months. The 2-year CIR was similar in pts who received IC or LIT with VEN (18% and 19%, respectively) and was highest in pts who received LIT without VEN (36%). The 2-year NRM was lowest in pts with LIT with VEN (11%), as compared with IC or LIT without VEN (27% and 22%, respectively) (P = 0.02 for IC vs. LIT with VEN). The 1-year post-SCT RFS for pts who received IC, LIT without VEN and LIT with VEN was 58%, 50%, and 75%, respectively, and the 2-year RFS was 54%, 42% and 62%. The 1-year post-SCT OS was 63%, 58%, and 84%, respectively, and the 2-year OS was 58%, 44% and 73%. OS was statistically superior for LIT with VEN compared with LIT without VEN (P = 0.02) and there was a trend towards superior OS with LIT with VEN compared to IC (P = 0.17). Conclusions: LIT with VEN was associated with similar rates of CIR and lower NRM compared with IC. Despite the older age of pts in the LIT with VEN cohort, their post-SCT survival outcomes were noninferior, and possibly superior, to those who received IC. These results suggest that LIT with VEN is a valid induction strategy for older SCT-eligible pts with newly diagnosed AML.

A phase Ib/II study of ivosidenib with venetoclax +/- azacitidine in IDH1-mutated hematologic malignancies

7018

Background: Isocitrate dehydrogenase-1 mutations ( IDH1+) result in production of the oncometabolite 2-hydroxyglutarate, arrested differentiation, and increased dependence on the anti-apoptotic protein BCL-2, enhancing susceptibility to the BCL-2 inhibitor venetoclax (VEN). Herein, we report the completed P1b portion of the P1b/II study combining the IDH1 inhibitor ivosidenib (IVO; 500 mg PO daily D15-continous) with VEN (D1-14), with or without azacitidine (AZA; 75mg/m2 D1-7 every 28 days). Methods: Eligible patients age 18 with IDH1+ MDS, newly diagnosed (ND: de novo and secondary/treated secondary AML) or relapsed/refractory (R/R) AML were enrolled into 4 dose levels (DL): DL1 (IVO+VEN 400 mg), DL2 (IVO+VEN 800 mg), DL3 (IVO+VEN 400 mg+AZA), DL4 (IVO+VEN 800 mg+AZA). Primary objectives included safety and tolerability, and IWG defined overall response (ORR: CR+CRi+CRh+PR+ MLFS). Results: 31 patients (DL1: 6, DL2: 6, DL3: 13, DL4: 6) enrolled with a median follow-up of 26 months. Median age was 67 years (range: 44-84). 71% had AML (ND: N = 14, R/R: N = 8), 29% (N = 9) had MDS. ELN risk was intermediate and adverse in 19% (N = 6) and 55% (N = 17). Median baseline IDH1+ VAF was 23% (5%-48%). Median time on study was 6.4 (range: 4 -not reached [NR]) months. The ORR was 94% (DL1: 67%, DL2-DL4: 100%); Composite CR (CRc: CR+CRi+CRh) was 87% (DL1: 67%, DL2: 100%, DL3: 85%, DL4: 100%). 63% of AML patients attained measurable residual disease negative CRc by multiparameter flow cytometry (ND-AML: 64%, R/R-AML: 60%). Addition of AZA increased MRD clearance in ND-AML compared to the doublet regimen (86% vs. 25%, p: 0.09). IDH1+ mutation clearance by digital droplet PCR (sensitivity: 0.1-0.25%) was attained in 67% of patients (ND-AML: 83%, R/R-AML: 50%, MDS: 50%) following cycle 5. 35% of patients required dose reductions for cytopenias (DL2: 2 [33%], DL3: 6 [46%], DL4: 3 [50%]). Grade 3-5 adverse events (AEs) occurring in 10% of patients included febrile neutropenia (29%; one episode resulted in death in a R/R-AML patient relapsing on study) and pneumonia (23%). AEs of special interest (AESI) included grade 3 tumor lysis syndrome in two patients (dose-limiting toxicity in one), and differentiation syndrome in 4 (G2: N = 2, G3: N = 2) patients. All AESIs were transient and reversible. Median EFS and OS were 36 and 42 months. 24-month OS was 71% (95% CI: 55-91; [ND-AML: 67%, R/R-AML: 50%, MDS: 100%]). MRD-negative CRc improved OS (median NR vs. 8 months, p: 0.002) in ND and R/R-AML. 100% of patients (N = 4) relapsing after IDH1+ clearance demonstrated no IDH1+ at relapse. Based on efficacy and toxicity, DL3 (IVO+VEN400+AZA) was the recommended phase 2 dose. Conclusions: IVO+VEN +/- AZA is an effective treatment for IDH1+ myeloid malignancies with an expected toxicity profile and notable efficacy across disease groups. Single-cell sequencing and CyTOF correlatives will also be presented. Phase 2 enrollment is ongoing. Clinical trial information: NCT03471260.

Phase II study of cladribine, idarubicin, cytarabine (CLIA) plus gilteritinib in patients (pts) with FLT3 mutated acute myeloid leukemia (AML)

e19036

Background: The addition of multi-kinase inhibitors of FLT3 such as midostaurin and sorafenib to chemotherapy have demonstrated improved outcomes in patients with newly diagnosed FLT3 mutated AML Gilteritinib (gilt) is a second generation FLT3 inhibitor approved for pts with relapsed/refractory (R/R) FLT3-mutated AML. We studied to the combination of gilt with the CLIA regimen in FLT3 mutated AML. Methods: Eligible pts were between 18-65 years (yrs) with FLT3-mutated AML. Induction was: Cladribine 5 mg/m2 IV on D1-5, Cytarabine 1.5-2.0 g/m2 IV on D1-5, Idarubicin 10 mg/m2 IV on D1-3 and gilt 120 mg on D1-14. Consolidation was cladribine 5 mg/m2 IV for 3d, Cytarabine 750 mg/m2 IV for 3 d, and idarubicin 8 mg/m2 IV for 2 d, with gilt 120 mg continuously during cycle two onward. A historical cohort combining sorafenib (400 mg PO BID) with idarubicin + cytarabine (1.5 g/m2) backbone was used as comparison. Results: Twenty-four pts were enrolled with a median age of 53 yrs (range, 28-63). 21 pts (88%) had FLT3-ITD, 6 pts (25%) had FLT3-D835, and 3 pts (13%) had both. Nineteen pts (79%) had diploid cytogenetics, and 4 pts (18%) had trisomy 8. The most commonly co-occurring mutations were: NPM1 (46%), ASXL1 (29%), DNMT3A (29%), TET2 (25%), and KDM6A (20%). 16 pts (67%) achieved complete remission (CR), 2 (8%) had CR with incomplete recovery (CRi), for a CR/CRi rate of 75%. 13 responding pts (54%) underwent to allogeneic SCT. The median overall survival for the entire cohort was not reached. We compared these outcomes to our historical cohort of 107 pts treated with sorafenib combined with high-dose cytarabine-based chemotherapy. Other than older age and greater anemia for the gilt, there was not significant difference in baseline characteristics between the two groups. The CR/CRi rate was similar (75% gilt vs. 71% sorafenib; P = > 0.999) between the 2 cohorts; while there was a trend, there was no significant difference in OS with CLIA + Gilt (median NR vs. 17.3 months for sorafenib; P = 0.533). Conclusions: The combination of the FLT3 inhibitor gilteritinib to CLIA produced high rates of complete remission in pts diagnosed with FLT3-mutated AML. These results were similar for Sorafenib when combined with intensive chemotherapy with OS rates favoring gilteritinib. Further study of intensive chemotherapy with different FLT3 inhibitors is warranted. Clinical trial information: NCT02115295.

Treatment-free remission (TFR) in patients with chronic myeloid leukemia (CML) following the discontinuation of tyrosine kinase inhibitors

7050

Background: Tyrosine kinase inhibitors (TKIs) discontinuation in patients (pts) with CML is increasingly considered. We evaluated the outcome of pts with CML who discontinued TKIs and determined the factors associated with differences in the success rates of TFR. Methods: We reviewed data from 284 pts with CML treated with TKIs at our institution between October 1999 and February 2017 and who subsequently discontinued therapy. Major molecular response (MMR) was defined as a BCR-ABL1/ABL1 transcripts ratio ≤0.1% as determined by real time (RT)-PCR, MR4 as a ratio ≤0.01% IS, and MR4.5 as a ratio ≤0.0032%. TFR failure was defined as the loss of MMR on any single test. We analyzed TFR rates according to duration and depth of response and conducted a multivariate analysis for factors associated with loss of MMR. Results: Median age was 63 years (range, 25-93). 199 pts (70%) had electively discontinued their TKI while 70 pts (24%) stopped therapy because of adverse events. 92 pts (32%) had switched ≥1 TKI prior to discontinuation due to drug intolerance or resistance. The median time from the initiation of frontline TKI to discontinuation was 117 months (range, 16-242). The median duration of MR4 and MR4.5 before TKI discontinuation was 74 months (range, 2-207) and 64 months (range, 0-207), respectively. At a median follow-up of 36 months (95% CI, 32-40) after TKI discontinuation, 53 pts (19%) lost MMR, translating into a 5-year TFR rate of 79%. 50 pts (94%) resumed TKI therapy and, among 47 evaluable pts, all but one pt regained MMR, with 41 pts (88%) achieving MR4.5. The estimated 5-year TFR rates were 91%, 76% and 70% in pts achieving MR4.5 for ≥6 years, between 5 and 6 years, and < 5 years, respectively (P < 0.0001). The estimated 5-year TFR rates were higher with MR4 and MR4.5 ≥5 years, compared with MR4 < 5 years (87% vs 92% vs 64%; P < 0.0001). Pts who remained on their frontline TKI at the time of discontinuation had a 5-year TFR rate of 82%, compared with 75% and 72% among pts who switched to a second line TKI or beyond because of intolerance or resistance, respectively (P = 0.417). TFR rates did not vary according to the type of frontline TKI used (P = 0.761). By multivariate analysis, only durations in MR4 or MR4.5 ≥5 years before stopping treatment were associated with a lower risk of loss of MMR, with hazard ratios of 0.37 (95% CI, 0.18-0.76; P = 0.007) and 0.20 (95% CI, 0.09-0.45; P < 0.0001), respectively. We evaluated the impact of the frequency of molecular monitoring on the success rate of TFR. The estimated 5-year TFR rate was 79% for pts monitored monthly compared with 85% for pts monitored every 6-8 weeks following discontinuation (P = 0.263). Conclusions: Our findings suggest that achieving MR4 for ≥5 years was associated with a very high probability of maintaining TFR, and that less frequent molecular monitoring could be more cost-effective without any negative impact on outcomes.

Phase 2 study of ASTX727 (cedazuridine/decitabine) plus venetoclax (ven) in patients with relapsed/refractory acute myeloid leukemia (AML) or previously untreated, elderly patients (pts) unfit for chemotherapy

7037

Background: ASTX727, is an oral formulation of the fixed dose combination of decitabine and cytidine deaminase inhibitor cedazuridine (100 mg/35 mg). We investigated whether a total oral therapy regimen of ASTX727+ven is feasible and safe. Methods: Pts aged ≥18 years (yrs) with relapsed/refractory AML (R/R) or pts with AML aged ≥ 75 or 18 -74 with comorbid conditions prohibiting intensive chemotherapy were eligible to participate (frontline-FL). Other eligibility criteria included adequate renal and hepatic function, and an ECOG performance status (PS) of≤2. ASTX727 is administered daily on days 1‐5 of each cycle and ven on days 1‐28 of the first cycle after a dose ramp up of 100-200-400 mg over 3 days (with tumor lysis prophylaxis precautions and with ven dose adjustments as needed). A bone marrow exam is performed on day 21±3 days and ven is held if blasts < 5% to allow count recovery. Cycles are repeated every 4-8 weeks and ven is administered for 21 days in subsequent cycles. Results: Between March 2021 and January 2022, 28 pts (15 FL and 13 R/R) have been treated on the study. The median age is 75 yrs (range, 47-90) with FL cohort 81 and R/R cohort 72. 9 FL pts (60%) were ≥80 and 5 (30%) 70-80 yrs. In R/R cohort 9 pts (69%) were 70-80 yrs. The median PS is 2 (range 0-3) and in the R/R cohort, the median number of prior treatments is 2 (range, 1-4). In the FL cohort 5 (33%) had normal and 6 (40%) a complex karyotype; 3 had other. In the R/R cohort, 15% had normal karyotype, 46% complex and 31% others. Mutations of note in the frontline cohort were RUNX1 (33%), ASXL1 (33%), DNMT3A (7%), TET2 (40%) and TP53 (20%). The overall response rate (ORR) including complete response (CR), CR with incomplete count recovery (CRi) and morphological leukemia free state (MLFS) in the FL cohort is 61% (4 CR, 4 CRi, 1 MLFS and 3 non-responders). 3 pts received only one day of therapy for severe adverse events unrelated to therapy (1 due to ischemic stroke, 1 septic shock and 1 debilitation) and were not evaluable for response. In the R/R cohort, the ORR was 45% (2 CR, 2 CRi, 2 MLFS with 5 non-responders and 2 not evaluable). The median number of cycles received is 2 (range, 1-5) for both cohorts. With a median follow-up of 5 months, the median survival for the FL cohort has not been reached (range, 0.6 – 7.3) and is 7.2 (range, 0.8-7.3) months for the R/R cohort. Grade 3 or higher adverse events directly attributable to therapy were mainly myelosuppression-related and included neutropenic infections in 3 (11%) and elevation of liver enzymes in 1 (4%) pt. Conclusions: Total oral therapy of ASTX727+ven is safe and feasible, particularly in the advanced elderly population, and demonstrates significant efficacy in pts unfit for chemotherapy both in the FL and R/R settings. Clinical trial information: NCT04746235.

Phase 1 study of LP-108 as monotherapy and in combination with azacitidine in patients with relapsed or refractory myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), or acute myeloid leukemia (AML)

TPS7071

Background: BCL2 inhibition as a means of targeting intrinsic apoptotic pathways that confer a survival advantage to leukemic blasts has become a key therapeutic strategy for patients with myeloid malignancies. LP-108 is an oral highly potent and selective inhibitor of BCL-2 with comparable or more potent in vitro inhibitory activity as compared to the FDA approved oral BCL-2 inhibitor venetoclax. We propose to investigate LP-108 as monotherapy and in combination with azacitidine in patients with relapsed or refractory (r/r) MDS, CMML or AML. Methods: The primary objectives of the trial are 1.) To determine the safety, tolerability and determine the maximum tolerated dose (MTD) and the recommended phase 2 dose / optimal biological dose (OBD) of LP-108 as a single agent (Arm 1) and in combination with azacitidine (Arm 2) in patients with relapsed/refractory MDS/CMML/AML; 2.) To characterize the pharmacokinetic profile of LP-108 as monotherapy and in combination with a fixed dose of azacitidine. The secondary objectives of the trial are 1.) To evaluate the objective response rate of LP-108 (monotherapy or combination therapy) in r/r MDS/CMML/AML as well as progression free survival, duration of response and overall survival. In Arm 1 patients will be enrolled according to a 3+3 design with escalating doses of LP-108 for a 28 day cycle (firs table). DLTs will be determined in the first 28 days. In Arm 2 patients will be enrolled according to a 3+3 design with escalating doses of LP-108 in combination with a fixed dose of azacitidine (second table). DLTs will be determined in the first 28 days. DLT for both arms is defined as some ≥ Grade 3 non-hematological toxicities or prolonged myelosuppression. Patients may continue treatment until disease progression, unacceptable toxicity, or per investigator discretion. Patients age ≥ 18 years with r/r MDS with excess or blasts or with high or very-high risk disease per the R-IPSS, or r/r MDS for Arm 2, r/r AML, or frontline older and/or unfit AML for Arm 2, or r/r CMML may enroll. Patients with prior hypomethylating agents or venetoclax exposure may enroll. The blast count at the time of starting therapy must be ≤ 30 x 109 cells/L. Hydroxyurea is allowed prior to and during treatment. Ejection fraction ≥ 50% is required. Calculated creatinine clearance shall be ≥ 30 mL/min. Strong CYP3A4 inducers and inhibitors are prohibited. Patients on weak/moderate azole antifungals were allowed to enroll. Enrollment to Arm 1 is complete and there have been no DLTs to date. Enrollment to Arm 2 is pending. Arm 1 Dose Escalation Scheme (LP-108 monotherapy). Clinical trial information: NCT04139434. [Table: see text][Table: see text]

Quizartinib (QUIZ) with decitabine (DAC) and venetoclax (VEN) is active in patients (pts) with FLT3-ITD mutated acute myeloid leukemia (AML): A phase I/II clinical trial

7036

Background: QUIZ, a potent 2nd generation FLT3 inhibitor (FLT3i) demonstrated synergy with VEN in AML cell lines and PDX models (Mali Haematologica 2020). We evaluated the safety and efficacy of DAC + VEN + QUIZ triplet in patients with newly diagnosed (ineligible for intensive induction chemotherapy) or relapsed/refractory (R/R; up to 5 prior chemotherapies) FLT3 ITD mutated AML. Methods: All pts received 10 days of DAC (20 mg/m2) in Cycle 1. Pts underwent day 14 bone marrow (BM) biopsy, and VEN (400 mg/day starting from day1) was put on hold in pts with BM blasts ≤ 5% or aplasia. Those with day14 BM blast >5% continued VEN for 21 days during cycle 1. In subsequent cycles, DAC was reduced to 5 days. QUIZ (30 or 40 mg/day) was administered daily continuously. Results: Overall, 28 pts were enrolled and evaluable at the time of this report. Of the 23 pts with R/R AML (median 3 [range 1-5] prior therapies, 78% with ≥1 prior FLT3i including prior gilteritinib (GILT) in 70%, and 39% had a prior ASCT), 78% achieved CRc (3 CR, 15 CRi) with 6/16 and 5/18 responders FLT3-PCR and multicolor flow cytometry (MFC) negative, respectively. Pts with RAS/MAPK mutations had the lowest response rates (Table). Interestingly, no emergent TKD mutations were noted at relapse after the triplet but 3/8 evaluable pts had emergent RAS/MAPK mutations. 60-day mortality rate was 5%. Of 5 patients with newly diagnosed AML (median age 69), all achieved CRc (2 CR, 3 CRi) with 4/5 and 2/4 responders FLT3-PCR and MFC negative, respectively. 60-day mortality was 0. 2 pts developed hematologic DLT with 40 mg/day QUIZ dose (grade 4 neutropenia with a <5% cellular BM lasting ≥42 days). Hence, QUIZ 30 mg/day dose was determined as RP2D for the triplet. Grade 3/4 non-hematologic toxicities included lung infections (42%) and neutropenic fever (30%). No QTcF prolongations >480 msec were noted. With a median follow-up (f/u) of 13 months, the median OS was 7.6 months in R/R cohort (1-year OS of 30%). 8/18 responding R/R pts (including 5/8 prior GILT exposed pts) underwent ASCT with a median OS of 19 vs 8 months in those who underwent ASCT versus not (p=0.26). Of the 5 frontline responding pts median OS was 14.5 months, 2 were alive in CR, 1 died in CR1 post-ASCT, 2 died due to relapsed disease at the last f/u. Conclusions: DAC + VEN + QUIZ is active in R/R FLT3-ITD mutated AML pts, with CRc rates of 78% and the median OS of 7.6 months. Interestingly, RAS/MAPK mutations but not emergent TKD mutations were associated with primary and secondary resistance to the triplet. Accrual continues, and updated clinical, NGS, and mass cytometry (CyTOF) data will be presented. Clinical trial information: NCT03661307. [Table: see text]

Magrolimab in combination with azacitidine for untreated higher-risk myelodysplastic syndromes (HR-MDS): 5F9005 phase 1b study results

7017

Background: Magrolimab is a monoclonal antibody that blocks CD47, a “don’t eat me” signal overexpressed on cancer cells. CD47 blockade by magrolimab induces macrophage-mediated phagocytosis of tumor cells and is synergistic with azacitidine (AZA) via upregulation of “eat me” signals. Here we report final Phase 1b data in patients (pts) with untreated HR-MDS (NCT03248479). Methods: Pts with previously untreated intermediate-/high-/very high-risk MDS per IPSS-R received magrolimab IV as a priming dose (1 mg/kg) followed by ramp-up to a 30 mg/kg weekly or Q2W maintenance dose. AZA 75 mg/m2 was administered IV or SC on Days 1–7 of each 28-day cycle. Primary endpoints were safety/tolerability and complete remission (CR) rate. Results: 95 pts (median age 69 years [range 28, 91]) were treated. IPSS-R risk was intermediate, high, or very high in 27%, 52%, and 21%, respectively. MDS was therapy-related in 22%; 26% (n=25) had a TP53 mutation and 62% had poor-risk cytogenetics (27% complex). Median (range) number of cycles was 6 (1, 27). The most common TEAEs included constipation (68%), thrombocytopenia (55%), anemia (52%), neutropenia (47%), nausea (46%), and diarrhea (44%). The most common Grade 3/4 TEAEs included anemia (47%), neutropenia (46%), thrombocytopenia (46%), and WBC count decreased (30%). 6 pts discontinued treatment due to AEs. 60-day mortality was 2%. Median Hb change from baseline (BL) at first post-dose sample was –0.7 g/dL (range –3.1, +2.4). CR and objective response (OR) rates were 33% and 75% with 31% of evaluable OR pts with abnormal cytogenetics at BL having cytogenetic CR. Median time to first OR, duration of CR (DCR), duration of OR, and PFS were 1.9, 11.1, 9.8, and 11.6 mos. OS rates at 12 and 24 mos were 75% and 52%, respectively (median NR with 17.1 mos follow-up for OS). For patients evaluated with sequential WES with a VAF cutoff of 5%, 3 of 3 pts with TP53 mutation who achieved CR had TP53 VAF <5% by C5D1. Favorable outcomes were observed in both TP53 mutant (40% CR, median OS 16.3 months) and wildtype pts (31% CR, median OS NR; Table). Conclusions: Magrolimab+AZA was well tolerated with promising efficacy in pts with untreated HR-MDS including those with TP53-mut and TP53-wt disease. A Phase 3 trial of magrolimab/placebo+AZA (ENHANCE: NCT04313881) is ongoing. Clinical trial information: NCT03248479. [Table: see text]

Phase II study of lower-intensity frontline therapy for newly diagnosed patients with AML who are unfit or otherwise not eligible for frontline clinical trials

e19028

Background: Pts with newly diagnosed(ND) AML often present with abnormal organ function, poor performance status (PS), concurrent active malignancies, and active infections precluding them from enrolling on frontline clinical trials, since standard eligibility routinely exclude them. We designed a lower-intensity regimen of cladribine plus low-dose cytarabine (LDAC) alternating with decitabine with less stringent inclusion criteria in ND pts unfit or ineligible for existing clinical trials. Methods: Pts >18 years with untreated AML and ineligible for other frontline AML clinical trials were enrolled (NCT01515527). Eligibility criteria included either creatinine ≥2mg/dL; or total bilirubin ≥2 mg/dL; active concurrent cancer, infection, or ECOG PS of 3 or 4; or ineligible for participation in a higher priority protocol. Induction was cladribine 5 mg/m2 IV on D1-5, Cytarabine 20 mg SQ twice daily on D 1-10, followed by consolidation with cladribine 5 mg/m2 IV on D1-3, Cytarabine 20 mg SQ twice daily on D 1-10 alternating with decitabine 20 mg/m2 IV, daily on D 1-5. Primary objective was 60-d survival rate. Results: 25 pts have been enrolled. The median age was 73 yrs (range, 52-82) with 76% aged ≥70 yo. 6 pts (24%) had concurrent active malignancy, 4 (16%) had baseline creatinine >2mg/dL, and 9 (36%) had PS ≥3. 76% were adverse risk per ELN 2017 (Table). Among 25 evaluable pts, 17 (68%) achieved a composite complete response (CRc) including 10 (40%) CR and 7 (28%) CR with incomplete count recovery (CRi). Among responders, 6 pts (35%) achieved MRD neg by flow. Of 7 pts with no response, all were ELN adverse risk. Median cycles to response was 1 (range: 1 - 4). 30- and 60 d mortality was 8% and 16%, respectively, including 2 pts (8%) who died due to pseudomonal sepsis on D8, and the other due to pneumonia on D11. At a median follow up of 9.4 months (range, 0.4- 19.9 m),median OS (6-mo OS% - 61 %), and EFS was 8.3 mo each (6-mo RFS% - 56 %) with a 60-d OS and EFS rate of 83% each, with a median RFS of 5.8 mo (2-mo RFS%-66%; 6-mo RFS% - 49 %). In this challenging patient population, this lower-intensity regimen was well tolerated, with an acceptable toxicity profile. Conclusions: In an unfit patient population of ND AML with high comorbidity burden, that were ineligible for other clinical trials, induction therapy with Cladribine plus LDAC was feasible and effective and can allow pts to achieve remission and move on to effective post-remission therapy. Clinical trial information: NCT01515527. [Table: see text]

Tolerability and efficacy of the first-in-class anti-CD47 antibody magrolimab combined with azacitidine in frontline TP53m AML patients: Phase 1b results

7020

Background: Magrolimab is a monoclonal antibody blocking CD47, a “don’t eat me” signal overexpressed on cancer cells such as acute myeloid leukemia (AML). This blockade induces phagocytosis of tumor cells and is synergistic with azacitidine (AZA) via upregulation of “eat me” signals. We report data from a Phase 1b trial of magrolimab+AZA in frontline TP53-mutant ( TP53m) AML. Methods: Patients (pts) with frontline AML not suitable for intensive chemotherapy received IV magrolimab starting with a priming dose (1 mg/kg) followed by ramp-up to 30 mg/kg QW or Q2W as maintenance dose. AZA 75 mg/m2 was given IV or SC on Days 1–7 of each 28-day cycle. Primary endpoints were safety/tolerability and complete remission (CR) rate by ELN 2017 criteria. Results: 72 TP53m AML pts were treated (Table). Common all-grade TEAEs were constipation (52.8%), diarrhea (47.2%), febrile neutropenia (45.8%), nausea (43.1%), fatigue (37.5%), decreased appetite (37.5%), thrombocytopenia (31.9%), peripheral edema (30.6%), and cough (30.6%). Most common Grade 3+ TEAEs were febrile neutropenia (37.5%), anemia (29.2%; Grade 3, 26.4%; Grade 4, 2.8%), thrombocytopenia (29.2%), pneumonia (26.4%), and neutropenia (20.8%). Objective response rate (ORR) by intent-to-treat was 48.6% (33.3% CR, 8.3% CR with incomplete hematologic recovery [CRi] / CR with partial hematologic recovery [CRh], 1.4% morphologic leukemia-free state [MLFS], 5.6% partial response). Stable disease was reported in 16.7%, progressive disease (PD) in 5.6%. 30- and 60-day mortalities were 8.3% and 18.1%, respectively. Response assessment was unavailable in 4.2% who discontinued due to AEs and 6.9% due to other, prior to the C3D1 assessment. Median time to CR/CRi was 2.2 months (mos; range 1.7–7.2) and to CR was 3.0 mos (range 1.8–9.6). 45.2% (14/31) of evaluable CR/CRi/CRh/MLFS pts achieved negative MRD by flow cytometry (investigator reported). Of 24 CR patients, 8 had a longitudinal TP53 VAF assessment, and 5/8 (63%) had VAF decreased to ≤5%. Treatment was stopped due to SCT in 9 pts (12.5%), PD 26 (36.1%), death 8 (11.1%), AE 13 (18.1%), and other 14 (19.4%). Median durations of CR and CR/CRi were 7.7 mos (95% CI: 4.7, 10.9) and 8.7 mos (95% CI: 5.3, 10.9), respectively. Median overall survival (OS) for the 72 pts was 10.8 mos (95% CI: 6.8, 12.8) with median follow up 8.3 mos. Conclusions: In high-risk frontline TP53m AML pts unsuitable for intensive chemotherapy, magrolimab+AZA showed durable responses and encouraging OS in a single-arm study. A Phase 3 trial in TP53m AML (ENHANCE-2; NCT04778397) of this combination vs standard of care is ongoing. Clinical trial information: NCT03248479. [Table: see text]

Clinical outcomes associated with azacitidine (AZA) monotherapy for treatment-naïve, higher-risk myelodysplastic syndrome (HR-MDS): A systematic literature review and meta-analysis

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Background: AZA is a standard of care for patients who have HR-MDS. Given the limited availability of large datasets describing outcomes in the current treatment paradigm of HR-MDS, this analysis aimed to aggregate clinical outcomes associated with AZA monotherapy for treatment-naïve HR-MDS. Methods: CENTRAL, EMBASE, and MEDLINE were searched to identify interventional, prospective, and retrospective observational studies in treatment-naïve HR-MDS (defined as intermediate-2 or high risk by IPSS or intermediate to very high risk by IPSS-R) using AZA monotherapy. Inclusion of observational studies was limited to those with n >20 in the AZA arm. Responses according to IWG 2000 or IWG 2006 including complete remission (CR) rate, overall response rate (ORR; defined as CR, marrow CR [mCR], partial response, and hematologic improvement), overall survival (OS), duration of response (DOR), and time to response (TTR) were extracted. Response rates were synthesized using random-effects models; median of medians was used for OS, DOR, and TTR. Results: Of 3250 abstracts identified, 34 publications describing 16 studies met inclusion criteria: 5 randomized controlled trials (RCTs), 3 prospective studies, and 8 retrospective studies. None of the response endpoints were reported in all studies (see Table). The pooled ORR ranged from 44% to 55% across RCTs, prospective, and retrospective studies. The pooled CR rates, reported in 2 RCTs (n=55), 1 prospective study (n=27), and 3 retrospective studies (n=509), were 14%, 11%, and 16%, respectively. The pooled CR rate across all studies (n=591) was 16% (95% CI: 13%, 19%). Pooled median OS (mOS) was 16.7 months (mo) in the 3 RCTs (n=161), 16.5 mo in a single prospective study (n=34), and 14.4 mo in the 5 retrospective studies (n=1472). Pooled mOS across all studies (n=1667) was 16.4 mo (95% CI: 12.0, 17.3). The pooled median DOR was 10.1 mo (95% CI: 9.1, 11.0), and the median TTR was 4.6 mo (95% CI: 3.0, 9.0). Conclusions: These findings provide evidence that benefit from AZA monotherapy in treatment-naïve HR-MDS patients is limited. Opportunity exists for novel therapies to increase response rates, improve the duration of responses, and prolong survival. [Table: see text]

Phase 1/2, open-label, dose-escalation, dose-expansion study of menin inhibitor DSP-5336 in adult patients with acute leukemia with and without mixed-lineage leukemia (MLL)-rearrangement (r) or nucleophosmin 1 (NPM1) mutation (m)

TPS7066

Background: DSP-5336, a menin MLL interaction inhibitor, elicited antitumor activity in MLL–r or NPM1m acute leukemia models in vitro and in vivo. An open-label, single-arm, phase 1/2 study (NCT04988555) will evaluate the safety and efficacy of DSP-5336 and determine the recommended phase 2 dose (RP2D) in patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) or acute lymphocytic leukemia (ALL). Methods: Patients aged ≥18 y with R/R AML, ALL, or acute leukemia of ambiguous lineage after ≥1 line of standard therapy, ECOG PS 0–2, and adequate organ function are eligible. Patients will receive DSP-5336 twice daily for 28 d/cycle. In phase 1, there will be two parallel escalation cohorts: patients who do not receive concomitant azole antifungal medication and patients who receive antifungal azoles (ie, posaconazole, voriconazole, or fluconazole); 21–30 patients will be enrolled during phase 1 into multiple ascending dose levels. Dose escalation will use a Bayesian logistic regression model. Phase 2 will enroll two arms: R/R AML with MLL –r and R/R AML with NPM1m (10 –20 patients/arm). Patients will be treated at the RP2D to evaluate clinical activity and safety. Clinical trial information: NCT04988555. [Table: see text]

Lemzoparlimab (lemzo) with venetoclax (ven) and/or azacitidine (aza) in patients (pts) with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS): A phase 1b dose escalation study

TPS7067

Background: Despite treatment advances, pts with AML or higher-risk MDS who are ineligible for standard intensive treatments still have poor survival, highlighting the need for novel therapies. Overexpression of CD47 is common in leukemic stem cells and AML blasts and correlates with poor clinical outcomes. Lemzo is an anti-CD47 antibody with red blood cell–sparing properties. Treatment with ven plus aza has shown favorable safety and efficacy in older/unfit pts with AML and higher-risk MDS. Blocking CD47 is hypothesized to hypersensitize AML cells to the antitumor activity of ven and aza. This study will evaluate the safety and dose-limiting toxicities (DLTs) of lemzo with ven + aza for pts with treatment-naïve AML, as well as lemzo with aza ± ven for treatment-naïve higher-risk MDS. Methods: This phase 1b, open-label, dose-escalation study (NCT04912063) is enrolling adults with: (1) treatment-naïve AML with adverse cytogenetic/molecular risk not suitable for induction therapy, with an Eastern Cooperative Oncology Group Performance Status (ECOG-PS) 0–2 (aged ≥75 years) or 0–3 (aged ≥18–74 years) excluding acute promyelocytic leukemia; or (2) treatment-naïve higher-risk MDS (Revised International Prognostic Scoring Score > 3) with < 20% bone marrow blasts, ECOG-PS 0–2, and no immediately planned stem cell transplant. For each 28-day cycle, aza is administered subcutaneously or intravenously (IV) daily for 7 days within the first 9 days (7-0-0 or 5-2-2 schedule); ven is administered orally daily on days 1–28 (AML, following dose ramp-up) or days 1–14 (ven-containing MDS cohorts). Lemzo is administered IV at a schedule that is to be determined in this study. Dose escalation has Bayesian optimal interval design and may be expanded to investigate alternate dosing for lemzo. Dose expansion will initiate at recommended phase 2 dose. Treatment discontinuation criteria are unacceptable toxicity, progressive disease, lack of partial/complete remission or clinical benefit within 6 cycles, or at physician’s discretion. Pts who discontinue study treatment without progression will continue with posttreatment follow-up; pts who progress will enter survival follow-up. The primary endpoints are DLTs of lemzo. Secondary endpoints for both cohorts include best overall responses of complete remission, duration of response, event-free survival, and overall survival. Exploratory biomarker endpoints are included. Safety assessments include adverse event (AE, graded per National Cancer Institute Common Terminology Criteria for AEs v5.0) monitoring, physical examinations, vital signs, electrocardiograms, and laboratory tests. Response rates will be analyzed with estimates and 95% confidence intervals based on exact binomial distribution. Time-to-event endpoints will be analyzed using Kaplan–Meier methodology. Clinical trial information: NCT04912063.

Results of a phase 1 trial of azacitidine with venetoclax in relapsed/refractory higher-risk myelodysplastic syndrome (MDS)

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Background: The prognosis of patients with higher-risk (HR) MDS after hypomethylating agent (HMA) failure is poor with a survival of 4-6 months (Garcia-Manero et al, Lancet Oncology 2016). The combination of azacitidine (Aza) with venetoclax (Ven) in frontline HR MDS is very active (Garcia JS et al, ASH 2021). Methods: This is a phase 1 study evaluating patients ≥ 18 years old after HMA failure with adequate organ function and performance status were enrolled. HMA failure was defined as relapse or progression after ≥ 4 cycles of HMA. Patients with prior Ven exposure were excluded. All patients received Aza 75mg/m2 IV/SC on D1-5. A 3+3 Ven dose escalation was utilized; patients at dose level 0 (DL0), 1 (DL1), and 2 (DL2) received 100 mg, 200 mg, and 400 mg respectively on D1-14. The IWG2006 criteria was utilized to assess response. Results: To date, 12 patients have been enrolled (3 in DL0, 3 in DL1, and 6 in DL2) with a median age of 78 years (range: 67-82). The median bone marrow blasts at enrollment was 9% (range: 6 – 17%) with a median ANC, Hgb, and PLT of 1.15 K/µL, 7.5 mg/dL, and 33 K/µL respectively. When stratified based on cytogenetics, 6 (50%) patients had intermediate risk, 2 (17%) had poor risk, and 4 (33%) had very poor risk cytogenetic alterations. When stratified based on IPSS-R criteria, 2 (16%) had intermediate, 5 (42%) had high, and 5 (42%) had very high risk disease. ASXL1 (50%) and TP53 (42%) mutations were most the common mutations on next generation sequencing. The most frequently observed grade 3-4 adverse events(AE) were cytopenias, occurring in all patients. Four (33%) patients had grade 3-4 cytopenias, either thrombocytopenia or neutropenia, that were attributed to the drug combination, with 3 patients consequently requiring dose reductions. At the time of data cut-off, response was seen in 8 patients with an overall response rate of 75%. The median number of cycles to response was 1 (range: 1-4). One patient achieved a CR. Seven patients achieved a marrow response with 2 having neutrophil recovery and 2 with platelet recovery. Three patients achieved transfusion independence. One patient underwent allogeneic stem cell transplantation after receiving 7 cycles. Four patients had no response with 3 of those having TP53 mutations. With a median follow-up of 13.6 months, the mOS is 8.5 months with a 30-day and 60-day mortality of 8% and 17% respectively. Early mortality was related to infection in 1 patient and disease progression in the other. Conclusions: This phase 1 study in patients with relapsed/refractory HR MDS suggests potential benefit with the addition of Ven to HMA with a 75% overall response and a mOS of 8.5 months. TP53 mutations and complex karyotypes still confer poor prognosis despite the addition of Venetoclax. Overall, this combination was well-tolerated with treatment-related AEs primarily consisting of thrombocytopenia and neutropenia. The study continues to accrue. Clinical trial information: NCT04550442.

Treatment outcomes for newly diagnosed, untreated TP53-mutated acute myeloid leukemia: A systematic review and meta-analysis

e19020

Background: TP53 mutations are present in 10%–15% of patients with acute myeloid leukemia (AML) and are associated with resistance to therapy and poor outcomes. Currently available frontline therapies for TP53-mutated ( TP53m) AML include intensive chemotherapy (IC), hypomethylating agents (HMA), and venetoclax combined with HMA (VEN+HMA). This systematic review and meta-analysis evaluated outcomes associated with IC, HMA, and VEN+HMA in newly diagnosed, untreated TP53m AML. Methods: EMBASE and MEDLINE were searched May 20, 2021 to identify studies of interest. Single-arm data on complete remission (CR), CR with incomplete hematologic recovery (CRi), median overall survival (mOS), event-free survival (EFS), and duration of response (DoR) were extracted and pooled for each treatment. Response rates were pooled using random-effects models; the median of medians method was used for time-related outcomes. Results: Of 3006 abstracts identified, 17 publications describing 12 studies met the inclusion criteria: 6 were randomized clinical trials (RCTs), 2 were single-arm trials, and 4 were retrospective studies. Outcomes are displayed in the Table. CR rate was highest with IC at 43% (95% CI, 30%, 56%), followed by VEN+HMA, 33% (22%, 47%), and HMA alone 21% (7%, 49%). Rates of CR/CRi were 49% (37%, 60%) for VEN+HMA, 46% (39%, 53%) for IC, and 13% (2%, 48%) for HMA alone. mOS was similarly low across the 3 treatments: IC, 6.5 months (N=155; 5.1, 8.5); VEN+HMA, 6.2 (N=73; 5.2, 7.2); HMA, 6.1 (N=34; 4.9, 7.2). Conclusions: CR, CR/CRi, and mOS were low across all treatments for patients with newly diagnosed, untreated TP53m AML. Addition of venetoclax to HMA showed a trend toward improved response vs HMA alone but not for mOS. There is a significant unmet need for more effective treatment for this very difficult-to-treat population. [Table: see text]

A phase II trial of a chemotherapy-free combination of ponatinib and blinatumomab in adults with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL)

7009

Background: Ponatinib and blinatumomab are highly active in Ph+ ALL. A chemotherapy-free combination of these agents may lead to durable remissions and reduce the need for stem cell transplant (SCT) in first remission. Methods: In this phase II study, adults with newly diagnosed (ND) Ph+ ALL, relapsed/refractory (R/R) Ph+ ALL, or CML in lymphoid blast phase (CML-LBP) received up to 5 cycles of blinatumomab. Ponatinib 30mg daily was given during cycle 1 and decreased to 15mg daily once a complete molecular response (CMR) was achieved. After completion of blinatumomab, ponatinib was continued for at least 5 years. All patients (pts) received 12 doses of prophylactic IT chemotherapy. Results: Between 2/2018 and 1/2022, 55 pts were treated (35 ND, 14 R/R and 6 CML-LBP). Baseline characteristics and responses are shown in Table. Among 23 pts with ND Ph+ ALL evaluable for response, 22 (96%) achieved CR/CRi; 1 pt had early death due to myelosuppression from prior chemotherapy. Among 13 evaluable pts with R/R Ph+ ALL, 12 (92%) achieved CR/CRi. The CMR rates for the ND, R/R and CML-LBP cohorts were 64%, 71%, and 17% after cycle 1 and were 85%, 79%, and 33% overall, respectively. In the ND cohort, 4/17 evaluable pts (24%) achieved CMR in the peripheral blood within 1 week, and 9/15 (60%) within 2 weeks. The median follow-up is 11 months (range, 1-46+ months). Among the 35 pts in the ND cohort, 33 pts (94%) are alive and in continuous remission. Only 1 pt in the ND underwent SCT in first remission (due to persistent MRD positivity), and no relapses have been observed. The 2-year EFS and OS rates in the ND cohort are 93%. Among the 13 responding pts in the R/R cohort, 6 (46%) underwent SCT. The 2-year EFS and OS rates for the R/R cohort are 42% and 61%, and for the CML-LBP cohort are 33% and 60%, respectively. Most side effects were grade 1-2 and were consistent with the known toxicity profile of the two agents individually. Two pts discontinued ponatinib due to toxicity (1 due to stroke and 1 due to DVT). One pt discontinued blinatumomab due to recurrent neurotoxicity. Conclusions: The chemotherapy-free combination of ponatinib and blinatumomab was safe and effective in Ph+ ALL and CML-LBP. Longer follow-up continues to demonstrate durable remissions, particularly in ND Ph+ ALL, even without SCT in first remission. Clinical trial information: NCT03263572. [Table: see text]

Updated results from a phase II study of mini-hyper-CVD (mini-HCVD) plus inotuzumab ozogamicin (INO), with or without blinatumomab (Blina), in older adults with newly diagnosed Philadelphia chromosome (Ph)-negative B-cell acute lymphoblastic leukemia (ALL)

7011

Background: INO and Blina improve overall survival (OS) in patients (pts) with relapsed/refractory B-ALL. The use of these agents in older adults in the frontline setting may allow for use of less chemotherapy and improve remission duration and OS compared to standard therapies. Methods: Pts ≥60 years with newly diagnosed Ph-negative B-cell ALL received mini-HCVD for up to 8 cycles. Initially, INO was given at 1.3-1.8mg/m2 on day 3 of cycle 1 and 0.8-1.3mg/m2 on day 3 of cycles 2-4. Rituximab (if CD20+) and prophylactic IT chemotherapy were given for the first 4 cycles. Responding pts received POMP maintenance for up to 3 years. Beginning with pt #50, INO was given in fractionated doses each cycle (0.6 mg/m2 on day 2 and 0.3 mg/m2 on day 8 of cycle 1; 0.3 mg/m2 on day 2 and 8 of cycles 2-4) and 4 cycles of Blina were given following 4 cycles of mini-HCVD plus INO. Maintenance was with 12 cycles of POMP and 4 cycles of Blina (1 cycle of Blina after 3 cycles of POMP). Results: Characteristics of the 80 pts are shown in Table. 6 pts were in complete remission (CR) at enrollment. Among 74 evaluable pts, 73 (99%) responded (CR in 89%). MRD negativity by flow was achieved in 80% of pts after 1 cycle and in 94% overall. The 30-day mortality rate was 0%. Among 79 responders, 11 (14%) relapsed, 4 (5%) underwent SCT, 33 (42%) remain in ongoing continuous remission, and 31 (39%) died in remission. Notably, 6 pts (8%) developed veno-occlusive disease, 1 after subsequent SCT. With a median follow-up of 55 months, the 5-year continuous remission and OS rates were 76% and 47%, respectively. Age ≥70 and poor-risk cytogenetics were associated with worse outcomes. The inferior outcomes in pts ≥70 years was primarily due to higher rates of death in CR. The 5-year OS for pts age 60-69 years without poor-risk cytogenetics (n=37), age 60-69 with poor-risk cytogenetics (n=13), age ≥70 without poor-risk cytogenetics (n=24) and age ≥70 with poor-risk cytogenetics (n=6) were 69%, 39%, 36% and 0%, respectively. Conclusions: The combination of mini-HCVD plus INO, with or without Blina, in older adults with newly diagnosed Ph-negative ALL resulted in an overall response rate of 99% and a 5-year OS rate of 47%. Particularly favorable outcomes were seen in pts age 60-69 years without poor-risk cytogenetics (5-year OS: 69%). Chemotherapy-free regimens may improve outcomes in pts age ≥70 years, and novel agents/regimens are still needed for those with poor-risk cytogenetics. Clinical trial information: NCT01371630. [Table: see text]

Phase 2 study of azacitidine (AZA) and venetoclax (VEN) as maintenance therapy for acute myeloid leukemia (AML) patients in remission

e19018

Background: Most patients (pts) with AML achieve remission with current therapies but rates of relapse are high. Maintenance with oral AZA (CC-486) has been shown to prolong overall survival (OS) and relapse-free survival (RFS) in SCT-ineligible patients with AML in remission. The addition of VEN to maintenance regimens should be explored. Methods: We designed a phase 2, single-center, single-arm study to evaluate the efficacy and tolerability of AZA + VEN maintenance in AML. Pts ≥ 18 years in first remission (CR1) after induction and 1+ consolidations not immediately eligible for SCT were treated with AZA 50 mg/m2 IV/SQ on D1-5 and VEN 400 mg on D1-14 (or D1-7 at physician discretion) every 28 days, up to 24 cycles. Pts in CR2 and beyond were eligible if positive for minimal residual disease (MRD). Both intensive (INT; int/high dose cytarabine-based) and low-intensity (LOW; HMA/LDAC-based) induction regimens were permitted, including prior VEN. The primary outcome was modified RFS (mRFS; enrollment to relapse or death). Key secondary objectives were OS (enrollment to death), safety, and MRD clearance. Results: As of Feb 10 2022, 33 pts have been enrolled (characteristics in Table). The median number of cycles given is 6 (range 1-23). 20 pts (61%) received 7 days and 13 (39%) received 14 days of VEN. To date, 8 relapses and 6 deaths (all after relapse or SCT) have occurred. 5 pts (15%) have gone off protocol for SCT (censored at time of SCT). Median mRFS is not reached (NR) in both the INT and LOW cohorts (1-yr mRFS 73.9% and 58.3%, respectively). When stratified by ELN 2017, mRFS was NR, NR, and 4 mo for favorable, intermediate, and adverse risk, respectively (6-mo mRFS 92.3%, 90%, and 44.4%). Median OS is NR in both the INT and LOW cohorts (1-yr OS 93.8% and 53.3%, respectively). mRFS was numerically higher in pts with VEN exposure as part of their induction regimen (1-yr mRFS 79.1% vs 55.6% in non-VEN-exposed pts, p=0.067). Of the 7 MRD(+) pts at enrollment, 2 (29%) cleared their MRD on AZA/VEN maintenance. MRD(+) pts had a median mRFS of only 4 mo compared to NR in the MRD(-) pts (p=0.001). The MRD(+) pts in our study were very high risk (5/7 ELN adverse, 3/7 complex karyotype). The most common grade 3/4 AEs were infections (18%), thrombocytopenia (15%), neutropenia (12%), and neutropenic fever (6%). 4/33 pts (12%) required C2 VEN dose reduction for cytopenias. Conclusions: AZA/VEN maintenance is effective and tolerable in AML pts not immediately eligible for SCT after intensive or low-intensity induction. The regimen yields encouraging mRFS and OS durations. Longer follow-up and comparative studies are needed to confirm these initial results. Clinical trial information: NCT04062266. [Table: see text]

Acute myeloid leukemia with KMT2Ar and association with risk of bleeding and early mortality

7026

Background: Acute myeloid leukemia (AML) with rearrangement of KMT2A is characterized by chemotherapy resistance and high rates of relapse. However, additional causes of treatment failure or early mortality have not been well-defined in this entity. Methods: In a retrospective analysis, we compared causes and rates of early mortality following induction treatment between a cohort of adults with KMT2Ar AML (N=172) and an age-matched cohort of patients (pts) with normal karyotype (NK) AML (N=522). Results: The 30 and 60-day (60d) mortality in pts with KMT2Ar AML were significantly higher compared to those with NK AML, with rates of 10% (17/172 pts) and 15% (26/172 pts) in KMT2Ar AML vs 4% (20/522 pts) and 7% (38/522 pts) in NK AML, respectively ( P=0.004). Among those who died within 60d, the most common contributing cause in KMT2Ar was respiratory failure without a clear infectious etiology in 38% (10/26 pts) vs 11% (4/38 pts) in NK AML ( P=0.01). We found 42% (11/26 pts) with KMT2Ar AML who died within 60d were either diagnosed with or had high clinical suspicion for diffuse alveolar hemorrhage (DAH) that warranted empiric therapy vs 18% (7/38 pts) with NK AML ( P=0.05). Given the high occurrence of DAH in KMT2Ar AML, we set out to quantify bleeding events and recorded major and minor bleeds as defined by the International Society of Thrombosis and Haemostasis. We found 65% (17/26 pts) with KMT2Ar AML had at least one bleeding event vs 32% (12/38 pts) with NK AML ( P=0.01). There was a significantly higher frequent occurrence of major bleeds (rate ratio=6.22; P=0.005) and total bleeding events (rate ratio=4.5; P=0.001) in KMT2Ar AML vs NK AML. KMT2Ar was associated with disseminated intravascular coagulopathy (DIC), as 93% of evaluable pts (14/15 pts) vs 54% (7/13 pts) in NK AML had overt DIC before death. Longitudinal trajectories of DIC parameters of pts who died within 60d showed significantly higher prothrombin time levels ( P=0.008) in KMT2Ar. In a multivariate analysis, KMT2Ar and a monocytic phenotypic were the only independent predictors of any bleeding event in pts who died within 60d (OR 3.5, 95% CI 1.4-10.4, P=0.03; OR 3.2, 95% CI 1.1-9.4, P=0.04). Conclusions: KMT2Ar AML is associated with higher early mortality and an increased risk of bleeding and coagulopathy compared with NK AML. Early recognition and aggressive management of DIC and coagulopathy are important considerations that could mitigate the risk of death during induction treatment.[Table: see text]

Outcomes of patients with newly diagnosed acute myeloid leukemia (AML) and hyperleukocytosis

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Background: Hyperleukocytosis in AML is associated with inferior outcomes. Analyzing the factors associated with mortality in AML patients (pts) with a white blood cell count (WBC) ≥100 x 109/L can guide management and improve early mortality. Methods: We reviewed data from 129 pts with newly diagnosed AML presenting at our institution with WBC ≥100. Logistic regression models estimated odds ratios (OR) for 4-week mortality and Cox proportional hazard models estimated hazard ratios (HR) for overall survival (OS). Results: Median age was 65 years (range 23-86). 66% of pts had ECOG performance status (PS) <2. Median WBC was 146 (range 100-687) and 78 pts had clinical leukostasis (CL) including renal failure in 31 pts (24%), new onset hypoxia in 29 pts (23%), headache in 19 pts (15%), chest pain in 9 pts (7%) and neurological symptoms in 3 pts (2%). 29 pts (22%) had poor cytogenetics. FLT3 and RAS pathway mutations were found in 63% and 27% of pts, respectively. Compared with pts without evidence of CL, pts with CL were less likely to have good PS (ECOG PS <2, 58% vs 82%; P = 0.006), had higher 4-week (16% vs 2%; P = 0.015) and 8-week mortality (19% vs 6%; P = 0.038). Cytoreduction consisted of hydroxyurea in 124 pts (96%), cytarabine in 69 pts (54%) and leukapheresis in 31 pts (24%). Pts who underwent leukapheresis were less likely to receive cytarabine compared with pts who did not (35% vs 59%; P = 0.02); and tended to have more CL compared with pts who did not (74% vs 56%; P = 0.09). 30 pts had tumor lysis syndrome (TLS). TLS risk did not increase with WBC and was not associated with the cytoreductive modality used. 11 pts had intracranial hemorrhage (ICH): 9 pts (82%) with WBC ≥150 and 18% with WBC <150 (P = 0.048). No association was observed between the incidence of ICH and the cytoreductive therapy. 4-week and 8-week mortality rates were 10% and 14%, respectively. After a median follow-up of 49.4 months [mos] (95% CI 26.2-72.6), median OS was 14.3 mos (95% CI 7-21.6), with 2-year OS of 40%. Median OS was 12.3 mos (95% CI 7.4-17.2) compared with 29 mos (95% CI 2.1-55.6) in pts with or without CL, respectively (P = 0.007). Median OS was 9.9 mos (95% CI 7.5-12.2) and 21.3 mos (95% CI 10.7-31.8) among those who did or did not undergo leukapheresis, respectively (P=0.003). Median OS was 42 mos (95% CI 14.2-69.8) compared with 8 ms (95% CI 6-10) in pts < or ≥ 65 years. Conclusions: Older age, poor cytogenetics, TLS and DIC were associated with early mortality and inferior OS in pts with hyperleukocytosis. Careful monitoring of those pts with prompt cytoreduction and management of complications may help improve outcomes. [Table: see text]

The utility of the novel optimized HLH inflammatory (OHI) index for predicting the risk for mortality and causes of death in lymphoma

7570

Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may complicate hematologic malignancies (HM). We recently developed a simplified diagnostic and prognostic index termed the ‘optimized HLH inflammatory’ (OHI) index comprising the combined elevation of sCD25 ( > 3,900 U/mL) and serum ferritin ( > 1,000 ng/mL), which in HM patients both identifies HLH and predicts mortality more accurately than conventional criteria for HLH. In this study, we examined whether mortality in our cohort is directly related to progressive malignancy vs. HLH-associated causes in OHI+ and OHI- patients. Methods: We performed a multicenter, retrospective study of patients with newly diagnosed lymphoma from Israel, the USA, and Japan for whom sCD25 and ferritin levels were measured either as routine surveillance or during investigation for HLH and classified patients by their OHI status. The International Prognostic Index, International Prognostic Score, and Follicular Lymphoma International Prognostic Index were used to estimate the predicted prognosis of T/B cell non-Hodgkin’s lymphoma (NHL), Hodgkin’s lymphoma, and follicular lymphoma, respectively. Predicted five-year overall survival was calculated based on the relevant prognostic index and was compared between OHI+ and OHI- patients using the unpaired t-test. The actual survival at five years/last follow-up was recorded, as was the cause of death. The odds ratios (ORs) for observed vs. predicted mortality, and for HLH- vs. malignancy-related death were calculated using the Chi-square test. Results: 100 lymphoma patients were studied: 65% with B cell NHL, 18% with natural killer/ T cell lymphoma, 17% with Hodgkin’s lymphoma; 37 were OHI+, and 63 were OHI-. The disease-relevant international prognostic index-predicted five-year survival did not differ between OHI + and OHI- patients (a mean of 58% n OHI+ and 57% in OHI- p = 0.62). However, the observed five-year survival in OHI+ patients was lower (12%) than predicted, reflecting a mortality incidence that was four times higher than predicted by the relevant prognostic score (OR 3.9; CI 1.3-12.1). By contrast, OHI- patients had better survival (79%) than predicted by their prognostic scores (OR 0.15; CI 0.07-0.34). More than half of the OHI+ patients died from non-malignant causes (39% multi-organ dysfunction or HLH, 18% infection), while most OHI- patients (92%) died from progressive malignancy. The likelihood of dying from multi-organ dysfunction or HLH was 26 times higher in OHI+ vs. OHI- patients (OR 26.2; CI 4.1-286.7). Conclusions: OHI index status strongly correlated with mortality in patients with lymphoma within our cohort, and death in OHI+ patients was largely due to causes other than progressive malignancy. The OHI index appears to identify a harmful inflammatory state and deserves further prospective study.

Characteristics and outcomes of patients diagnosed with DNMT3A mutated acute myeloblastic leukemia

e19018

Background: Advances in molecular profiling have identified recurring gene mutations in acute myeloid leukemia (AML) that have independent prognostic significance with several being targets for the development of new small molecule inhibitors. DNMT3A mutations have been reported in up to 34% of patients with AML. Mutations of this gene are associated with silencing of tumor suppressor genes, thereby leading to leukemogenesis. Several prior reports have suggested an association with worse outcomes. Methods: We retrospectively reviewed records of 258 patients with ND AML with DNMT3A mutations who presented to our institution from 2002 to 2020. We analyzed their clinical and laboratory characteristics. We estimated their overall survival (OS) and disease-free survival (DFS) through the Kaplan-Meier method. P-value was 2-tailed, ≤ 0.05 was considered statistically significant with a confidence interval of 95%. Univariate and multivariate analyses were also applied. Results: Our cohort had a median age of 66 years, 56% were female. The majority of the patients (77%) had de novo AML and the M0 FAB subtype was predominantly observed in 70%. Diploid karyotype was detected in 60% while complex karyotype in 14% of patients. DNMT3A was most frequently mutated at codon 882 (64%). NPM1 was the most frequent concomitant mutation followed by FLT3-ITD and IDH2. Age > 65 years (p = 0.001) and presence of concomitant TP53 mutation (p < 0.001) were associated with worse survival and concomitant NPM1 was associated with a 40% reduction of death, p = 0.003. Secondary AML and concurrent TP53 mutation were associated with a higher risk of relapse, (p < 0.001 for both). Intensive chemotherapy (ICT) was administered to 82 patients of which 68 achieved a complete response or CR with incomplete count recovery (CRi). Nineteen patients were treated with Cladribine plus low dose Ara-C (Clad-LDAC) and CR or CRi was achieved in 16 patients. Eleven treated with Clad-LDAC-Ven and all achieved CR/CRi. Hypomethylating agents (HMA) were given to 22 patients of which 10 achieved CR/CRi. Twenty-five received HMA-Ven, of these, CR/CRi was achieved in 20 patients (p = 0.02). There was an 80% and 90% reduction of death with ICT, p < 0.001 and Clad-LDAC-Ven, p = 0.04 respectively. Moreover, the risk for relapse was reduced by 70% and 90% with ICT and Clad-LDAC-Ven respectively. Ninety-seven patients were treated with immunotherapy, FLT3 inhibitors, and IDH inhibitors, which were not included in this analysis. Conclusions: DNMT3A mutations have an independent prognostic impact in patients diagnosed with AML. Among these patients, older age, secondary AML, a concomitant mutation in TP53 showed a significant negative impact in terms of OS and DFS. Concomitant mutations in NPM1 and IDH2 were associated with better outcomes. Treatment with intensive chemotherapy or clad-LDAC-Ven was associated with the highest response rates.

A phase Ib/II study of ivosidenib with venetoclax +/- azacitidine in IDH1-mutated myeloid malignancies

7012

Background: Isocitrate dehydrogenase-1 ( IDH1+) mutations are present in 5-15% of myeloid malignancies, promoting leukemogenesis through production of the oncometabolite 2-hydroxyglutarate resulting in arrested myeloid differentiation. IDH1+ malignancies demonstrate increased reliance on the anti-apoptotic protein BCL-2, enhancing susceptibility to the BCL-2 inhibitor venetoclax (VEN). We report an interim safety and efficacy analysis of the IDH1 inhibitor ivosidenib (IVO; 500 mg PO daily D15-continuous) combined with VEN (D1-14) +/- azacitidine (AZA; 75mg/m2 D1-7 every 28 days). Methods: Eligible patients age ≥18 with IDH1+ MDS, newly diagnosed AML (ND: treatment naïve [TN] or secondary/treated secondary AML [sAML]), or relapsed/refractory (R/R) AML enrolled into three dose levels (DL): DL1 (IVO+VEN 400 mg), DL2 (IVO+VEN 800 mg), DL3 (IVO+VEN 400 mg+AZA). Primary objectives included safety and tolerability, and IWG defined overall response (ORR: CR+CRi+CRh+PR+MLFS). Prior receipt of IVO or VEN was exclusionary. Results: 25 evaluable patients (DL1: 6, DL2: 6, DL3: 13) enrolled with a median follow-up of 16.1 months. Median age was 67 (range: 44-84). 84% (N=21) of patients had AML (ND: N=13 [TN: 8, sAML: 5], R/R: N=8), while 16% (N=4) had MDS. ELN risk was intermediate and adverse in 16% (N=4) and 56% (N=14). Median IDH1 VAF at enrollment was 22.7% (range: 5.1%-47.8%). Two patients had received a prior IDH1 inhibitor. The ORR was 92% (DL1: 67%, DL2: 100%, DL3: 100%). Composite CR (CRc: CR+CRi+CRh) was 84% (DL1: 67%, DL2: 100%, DL3: 85%) including 92% (TN: 100%, sAML: 80%), 63%, and 100% of patients with ND-AML, R/R-AML, or MDS. Median number of cycles received was 4 (DL1: 8.5, DL2: 6, DL3: 4) with ongoing responses in 62% (DL1: 33%, DL2: 50%, DL3: 82%) at 1-year. 8 patients transitioned to SCT (DL1: 0, DL2: 2, DL3: 6), and 8 patients remain on study (DL1: 2, DL2: 1, DL3: 5). 1-year OS was 68% for the entire study population (DL1: 50%, DL2: 67%, DL3: 78%), 71% in ND-AML (TN: 86%, sAML: 60%), 50% in R/R-AML, and 100% in MDS. Measurable residual disease negative CRc by multiparameter flow cytometry was attained in 60% (ND-AML: 67%, R/R-AML: 60%, MDS: 33%) correlating with improved OS (median OS: NR vs. 8.5 months, p-value: 0.038). Common grade 3/4 adverse events included febrile neutropenia (28%) and pneumonia (24%). Tumor lysis and differentiation syndrome occurred in two and four patients; all cases resolved with medical management. Conclusions: IVO+VEN +/- AZA is an effective treatment regimen in patients with IDH1+myeloid malignancies. The combination therapy is associated with an acceptable and expected toxicity profile with notable efficacy and high rates of MRD-negative CRc in AML. Enrollment into the study continues. Clinical trial information: NCT03471260. [Table: see text]

Magrolimab + azacitidine versus azacitidine + placebo in untreated higher risk (HR) myelodysplastic syndrome (MDS): The phase 3, randomized, ENHANCE study

TPS7055

Background: MDS is a clonal myeloid disorder characterized by cytopenia and ineffective hematopoiesis. The median age of diagnosis is approximately 70 yrs of age and prognosis and treatment are guided by the Revised International Prognostic Scoring System (IPSS-R) criteria. Patients with intermediate, high and very high risk MDS (HR-MDS) have a median overall survival (OS) of 0.8 to 3.7 years. Despite the high unmet need in this patient population, azacitidine (AZA) is the only approved therapy for HR-MDS which has improved overall survival in clinical trials to date. However, these agents lead to low complete response (CR) rates (10-17%) with limited OS ( = 2 years), indicating a need for alternative therapy. Magrolimab is a first-in-class monoclonal antibody that blocks the macrophage inhibitory immune checkpoint CD47, a “do not eat me” signal overexpressed on tumor cells. Binding of magrolimab to CD47 leads to phagocytosis of tumor cells. AZA increases expression of prophagocytic “eat me” signals, facilitating synergy with magrolimab. In an ongoing phase 1b study, the combination of magrolimab + AZA led to high response rates (ORR 91%, with a CR of 42%) and an acceptable safety profile without significant immune-related adverse events. ENHANCE (NCT04313881) is a phase 3 trial comparing the efficacy and safety of magrolimab + AZA with that of AZA + placebo (PBO) in previously untreated patients with HR-MDS. Methods: Patients ≥18 years old with previously untreated intermediate to very high risk MDS by IPSS-R are eligible for ENHANCE. Randomization is 1:1 to magrolimab + AZA or AZA + PBO with no crossover allowed. Magrolimab or placebo is administered intravenously (IV) with an initial 1 mg/kg priming dose to mitigate on target anemia. An intrapatient dose escalation regimen up to 30 mg/kg is then administered through Cycle 1, 30 mg/kg weekly dosing in Cycle 2, with 30 mg/kg Q2W dosing occurring in Cycle 3 and beyond. AZA is administered per regional prescribing information. Patients may remain on treatment until disease progression, relapse, loss of clinical benefit, or until unacceptable toxicities occur. Two primary efficacy endpoints are CR rate and OS. For patients undergoing allogeneic stem cell transplantation (ASCT), data for the CR rate will be censored at the time of ASCT and OS will be censored at the last known alive date. Secondary efficacy endpoints include RBC transfusion independence rate, event-free survival, minimal residual disease-negative rate, time to AML transformation, and patient-reported Functional Assessment of Cancer Therapy (FACT)-Anemia response rate. Biomarkers of immune cell recruitment, immune cell signaling, and bone marrow penetration of magrolimab will also be explored. Planned enrollment is approximately 520 patients globally, which began in September 2020. Accrual is ongoing. Clinical trial information: NCT04313881.

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]