Baseline Bone Marrow Research Articles

The Profiling of Circulating Tumor DNA Liquid Biopsy in Children and Adolescent Lymphoblastic Lymphoma

Backgrounds: Next-generation sequencing (NGS) based on liquid biopsy has been an emerging technology to identify tumor-specific genetic aberrations in adult lymphoma. However, there were few studies on the genomic profiling of plasma circulating tumor-derived DNA (ctDNA) in pediatric and adolescent lymphoblastic lymphoma (LBL). Methods: Paraffin-embedded tissue (FFPE), plasma and bone marrow samples from the newly diagnosed patients were collected and sequenced by 475 genes panel before, during and post of treatment. Clinical stage system, risk stratification and treatment of lymphoblastic lymphoma according to modified BFM-95 protocol. Results: A total of 68 patients (50 T-LBL, 18 B-LBL) from 13 centers in China were included in this study, including 49 male and 19 female, 3 patients in the low-risk group, 30 in the intermediate-risk group, and 19 in the high-risk group, and 16 patients were not stratified. The baseline detection rate of tissue, plasma and bone marrow of the T-ALL/LBL patients were 96% (24/25), 97.14% (34/35), and 75% (12/16), respectively. The mean mutation abundance in baseline tissue (34.12%) was significantly higher than in plasma (15.16%) and bone marrow (13.93%). Regarding sample consistency compared with tissue, the sensitivity of baseline plasma and bone marrow were 73.83% (79/107, N=18) and 70.77% (46/65, N=10), respectively. Compared with plasma, the sensitivity of mutation detection in bone marrow samples was 67.29% (72/107%, N=14). There were no significant correlation between ctDNA mutation abundance, concentration and risk stratification, stage, and SUV of PET/CT. The most common molecular abnormality detected in tissue and plasma was NOTCH1 mutation (52.2% in tissue, 66.7% in plasma), and the mutation types were mainly missense mutation, deletion, and frameshift mutation, and also found rare NOTCH1 gene fusions (IKZF2: exon5~NOTCH1: exon28, NOTCH1: exon 30~IKZF2: exon6). Other high-frequency gene variants were CDKN2A (tissue 30.4%, plasma 18.2%), CDKN2B (tissue 30.4%, plasma 21.2%), JAK1 (tissue 34.8%, plasma 15.2%), BCL11B (tissue 4.3%, plasma 18.2%) FBXW7 (tissue 13%, plasma 21.2%), PTEN (tissue 13%, plasma 12.1%) and so on (Figure 1). A total of 24 patients underwent dynamic monitoring of two or more liquid biopsies (Figure 2), and all patients were positive in baseline plasma ctDNA. At the last follow-up time, 11 of 24 patients were at least 2 times positive for ctDNA examination, of whom 5 patients with tumor recurrence, progression or poor prognosis (3 cases poor response to induction IA chemotherapy with tumor shrunk less than 70%, 2 cases with tumor progression and 1 case with tumor relapsed) and 1 patient died of infection during consolidation treatment and 4 cases lost to follow-up. Twelve of 13 patients whose plasma ctDNA cleared at the second examination time achieved PR with tumors shrunk more than 70% after induction IA treatment and none of the 13 patients relapsed or disease progression. In B-LBL, the baseline detection rate of tissue, plasma and bone marrow were 75% (9/12), 100% (12/12), and 66.67% (4/6), respectively. The top five gene variants were CDKN2A (26.7%), FLT3 (26.7%), NRAS (26.7%), KRAS (20%), NTRK3 (20%). Conclusion: Plasma ctDNA testing by NGS was practicable in pediatric and adolescent lymphoblastic lymphoma and could well reflect the clinical efficacy and detect tumor recurrence. Nevertheless, it is necessary to expand the sample size and extend the follow-up time to explore the value of liquid biopsy in pediatric and adolescent lymphoblastic lymphoma. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

SC-gtCAR19, a Non-Viral Genome Targeting Anti-CD19 CAR-T Candidate in Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia: Updated Results from Long-Term Follow-up

Introduction It has been made great commercial success in hematological malignancies by chimeric antigen receptor (CAR) T cell therapy. However, high rate of adverse events (AEs) still remains an issue. Non-viral Genome Targeting CAR (gtCAR) delivery technology, which uses CRISPR-Cas9 to insert CAR DNA to TRAC locus specifically in human T cells, produces moderate CAR-T cells compared with conventional ones. Earlier results of SC-gtCAR19, an anti-CD19 gtCAR-T candidate from an investigator initiated Phase I clinical trial (ChiCTR2000031942) demonstrated a favorable benefit-risk profile in relapsed/refractory B-Cell Acute Lymphoblastic Leukemia (r/r B-ALL) patients. Reported here are updated long-term follow-up results. Objective The primary objective is to assess safety. Secondary objective is to evaluate efficacy. Level of CAR-T cell in blood was explored. Method This is a single center, open-label and single-arm trial. Patients or allogeneic donors underwent leukapheresis and their CD3+ T cells were selected and modified by non-viral vector to produce SC-gtCAR19. A standard lymphodepletion chemotherapy was performed. The median dose was 3.89×106CAR+ cells/kg (0.58-8.31×106/kg). AEs were graded according to CTCAE v5.0. Cytokine Release Syndrome (CRS) and neurological events (NEs) were graded by ASTCT consensus grading. Relapse defined as bone marrow (BM) blast or B-ALL related mutation gene positive from nonexistence regardless of specific value, and extramedullary disease (EMD) occurrence. Result As of May 1st 2022, twenty-two r/r B-ALL patients received SC-gtCAR19 (Table 1). The median age was 29 (13-61), and the median number of previous regimen was 5 (2-16). The median baseline BM blast after preconditioning was 44.1% (0.3-99%), particularly 73% of patents with high disease burden (>25% leukemic blast). Five patients (23%) once had stem cell transplantation (SCT), and 14 (64%) have B-ALL related chromosomal and molecular abnormalities. One patient has EMD. No patient has been treated by any other CD19 related therapy before enrollment. The most common AEs of any grade were anaemia (100%), pyrexia (91%), neutrophil count decreased (91%), and white blood cell count decreased (86%) (Table 2). CRS occurred in 20 patients (91%), and 4 of them (18%) with grade 3 CRS. The median time to CRS onset was 7 days (IQR 7-14), and the median duration of any grade CRS was 3 days (IQR 2-5). Three patents developed NEs, one was grade 2 and 2 were grade 3 (temporary seizure, related to infection and patient's cerebral infarction before enrollment). No fatal or life-threatening events happened. No Tocilizumab administered, four patients used vasopressors and 2 steroids for treatment of CRS. All patients were eligible for efficacy analysis. At Day 28, the overall response rate was 100%, with 9 (41%) patients achieving complete remission (CR), ten (45%) achieving complete remission with incomplete haematological recovery (CRi), and 3 (14%) with blast-free hypoplastic. Among them, twenty patients (91%) achieved minimum residual disease (MRD) negative CR, and those 2 patients with MRD positive CR were assessed undetectable BM MRD in Day 90. Patient with EMD, the nodal lesions in her breast disappeared at Day 60. At a median follow-up of 19.9 months (4.5-26.6), nineteen patients relapsed, within which 7 (36.8%) antigen escape relapse. The median duration of remission for 19 patients achieving CR/CRi was 8 months (2.5-NE). All patients received a consolidation treatment by Lenalidomide 3 months after infusion on condition of CR status until disease progression/death, and all of them did not receive SCT afterwards before relapse. As of the data cutoff, two patients (9%) had ongoing CR with median follow-up of 22.4 months. The median relapse-free survival for 19 patients was 8.9 months (2.9-NE) (Figure 1). The median OS was 24.2 months (3.7-NE) (Figure 2). CAR T cell level measured by cell copies percentage per peripheral blood mononuclear cells peaked at median 12 days (IQR 10-13) (Figure 3). The median peak percentage of copies was 53% (IQR 26.5-72.1%). Conclusion This study is the first clinical trial applied a gtCAR-T candidate for r/r B-ALL treatment. SC-gtCAR19 has a better risk-tolerance. Despite TCR gene knocked-out, gtCAR-T cell proliferation and its function both short and long term may not be influenced. We illustrate that this novel approach is feasible in terms of manufacture and clinical application. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Short Telomere Syndromes and Inherited Predisposition to Bone Marrow Diseases: The MDACC Experience

Introduction: Telomeres are noncoding nucleotide repeats at chromosomal ends, which provide genomic stability and are maintained and regulated by specific protein complexes. Their length physiologically decreases with age, although it is known that germline mutations in telomeric regulators can accelerate this process, which is related to a wide variety of clinical situations. Herein we report on the experience of patients diagnosed with Short Telomere Syndromes (STS) evaluated in the Hereditary Hematologic Malignancy Clinic (HHMC) of the MD Anderson Cancer Center. Methods: We retrospectively analyzed clinical characteristics and outcomes of patients with a diagnosis of STS referred or diagnosed in the HHMC. Germline mutation origin was confirmed by genetic analysis of cultured skin fibroblasts or blood/saliva in patients without hematologic disease. Telomere length was assessed by Flow-FISH techniques in a clinically validated external laboratory (John Hopkins Medical Laboratories, Baltimore, MD). Individuals with confirmed STS were recommended to follow a specialized cancer surveillance program to achieve early-diagnosis or prevention of potential complications related to STS. A baseline bone marrow evaluation was recommended to evaluate underlying morphology and assess for somatic comutations. Results: A total of 24 patients with STS were identified (13 males, 54%), with a median age of presentation to the clinic of 53 years old (5-78). Although the reasons of referral for STS testing for each individual patient were diverse, they can be summarized in these categories: unexplained cytopenia (n=9), myeloid malignancy with relevant PMH or FH (n=8), affected sibling (n=5), skin lesions (n=1) and multiple cancer diagnosis (n=1). Pathogenic or likely pathogenic germline variants were confirmed in the TERT gene (n=13, 54%), TERC gene (n=7, 29%), RTEL1 (n=2, 8%), while 2 patients had no telomere-related detectable mutations (Figure 1). Telomere flow-FISH confirmed age-predicted telomere length <1st percentile for age in 67(%). All patients underwent a bone marrow biopsy, being described as hypocellullar in 17 patients (71%). With the bone marrow evaluation, eleven patients were diagnosed with myelodysplastic syndrome (MDS, 46%), two patients with acute leukemia (myeloid and mixed phenotype, 8%), two patients with clonal cytopenia of unknown significance (CCUS, 8%), one aplastic anemia (4%) and eight patients (33%) did not have hematologic malignancy. During the follow-up, three patients underwent an allogeneic stem cell transplantation due to their hematologic disease. Solid neoplasms are frequent in patients with STS, and 11 patients (46%) had a PMH of at least one solid tumor with a median age of 54 (33-78 yrs). Squamous cell carcinoma was the most frequent histology (6/11 patients). Sixteen patients (67%) had a positive FH of cancer in one or more first or second-degree sibling. Pulmonary fibrosis (PF) was diagnosed in 4 patients (17%), two with TERT mutations and two with TERC mutations. Moreover, 7 patients (4 diagnosed with PF,30%) had a positive FH of PF in first degree siblings. Liver diseases were also frequent: 3 patients had non-alcoholic hepatic cirrhosis, one patient had chronic hepatitis with periportal fibrosis and one with idiopathic portal hypertension. One patient had received a liver transplantation and one required a lung transplantation prior to presentation to the HHMC. Finally, twelve patients (50%) were reported to have premature grey hair and eight patients were reported to have nail dysplasia and/or skin abnormalities related to STS (such as unexplained reticular rash). A summary of the described patients is depicted in Figure 2. Conclusion: STS are genetic diseases that can go unnoticed until adulthood. Patients with myeloid malignancies (especially MDS) with hypocellular bone marrow and suspicious findings (i.e. FH or PMH of PF, premature grey hair, long standing cytopenias) should be considered for underlying STS. An early diagnosis is essential to start cancer surveillance programs and provide timely genetic counseling to the patient and relatives. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Adct-602, a CD22 Targeting Antibody Drug Conjugate Bound to PBD Toxin in Adult Patients with Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia: A Phase 1 Trial

Introduction: Outcomes of patients (pts) with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) remain dismal. CD22 is expressed on lymphoblasts in >90% of pts with B-ALL and is an established therapeutic target. Inotuzumab ozogamicin is an approved CD22 targeting antibody for pts with R/R B-ALL; however, the toxin calicheamicin can lead to veno-occlusive disease (VOD) of the liver, especially after allogeneic SCT (allo-SCT). ADCT-602 is an antibody drug conjugate composed of a humanized monoclonal antibody directed against CD22 and conjugated to SG3199, a pyrrolobenzodiazepine (PBD) dimer cytotoxin. In preclinical studies, ADCT-602 demonstrated potent anti-tumor activity in mouse models of B-cell malignancies. We present here results from an ongoing phase 1/2 trial evaluating ADCT-602 in pts with R/R B-ALL (NCT03698552). Methods: This is an investigator-initiated phase 1/2 trial of ADCT-602 monotherapy in pts with R/R B-ALL. The primary objective of the phase 1 part is to assess the safety and determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of ADCT-602. The primary objective of phase 2 is to evaluate efficacy (CR/CRi rate). Eligible pts must be ≥18 years of age with R/R B-ALL with bone marrow blasts ≥5%. CD22 must be expressed in ≥20% blasts. Pts must have adequate organ function (creatinine ≤1.5 mg/dL; ALT and AST ≤2 times upper limit of normal (ULN), ≤5 times ULN if there is liver or bone involvement; total bilirubin ≤1.5 times ULN; LVEF ≥45%). A 3+3 dose-escalation design was used for phase 1. ADCT-602 was initially given IV once every 3 weeks; based on the PK data, the administration schedule was later amended to weekly infusions. Results: From November 2018 to July 2022, 21 pts (11 women, 10 men) with R/R B-ALL were enrolled and received treatment with ADCT-602. The median age was 39 years (range, 21-82) and pts had received a median of 5 (range, 2-9) prior therapies [inotuzumab ozogamicin 12/21 (57%); blinatumomab 18/21 (86%); venetoclax 12/21 (57%)]. A total of 8/21 (38%) had a prior CD19 CAR-T, including 1 pt who had both CD19 and CD22 CAR-T. Ten (10/21, 48%) pts had a prior allo-SCT, including 3 pts with 2 prior allo-SCT. The median pretreatment bone marrow blasts were 70% (range, 16-96). The median CD22 expression on blasts was 97% (range, 33.6-100). A total of 11 pts were treated in the Q3week schedule [30µg/kg, n=3; 60µg/kg, n=4; 90µg/kg, n=4]. As the PK data indicated rapid clearance of the antibody, the trial was amended to allow for weekly dosing. A total of 10 pts were treated at the weekly dose level [30µg/kg, n=3; 40µg/kg, n=4; 50µg/kg, n=3]. One pt (30µg/kg weekly dose level) had grade 4 thrombocytopenia possibly related to ADCT-602. One pt (50µg/kg weekly dose level) had a DLT of prolonged myelosuppression (marrow blast clearance without blood count recovery). No pt had VOD. Notably, all 3 pts treated at the 50µg/kg weekly dose level (a dose level expected to be close to RP2D) had evidence of anti-tumor activity (2 pts achieved MRD negative CR; one pt had bone marrow blast clearance). First pt at this dose level was a 26-yr-old with R/R B-ALL with PAX5-JAK2 fusion with 5 prior therapies including 2 CD19 CAR-T and an allo-SCT who achieved MRD negative CR and is receiving ongoing therapy in Cycle 5. Second pt at this dose level was a 66-yr-old with TP53- and KRAS-mutated B-ALL with 2 prior therapies including modified BFM regimen and blinatumomab who achieved MRD negative CR and is receiving ongoing therapy in Cycle 4. Third pt at this dose level was a 21-yr-old with TP53- and KRAS-mutated B-ALL with 4 prior therapies including inotuzumab and a CD19 CAR-T who had morphologic blast clearance without blood count recovery. Two additional pts treated at lower doses levels (1 each at 30µg/kg Q3week and 30µg/kg weekly schedule) achieved MRD negative CR. All responding pts had CD22 expression noted in >97% of the blasts by flow cytometry. Conclusions: In this phase 1 study in pts with very heavily pretreated R/R B-ALL with a median of 5 prior lines of therapy and high baseline bone marrow tumor burden, single-agent ADCT-602 was well tolerated with one pt with DLT noted at the 50µg/kg weekly dose level. Notably, all 3 pts treated at this dose level had evidence of clinical activity with 2/3 pts achieving MRD negative CR. Due to 1 pt with DLT at this dose level, this cohort is being expanded to treat 3 additional pts. This trial continues to accrue pts and updated data will be presented at the ASH meeting.

1506P Role of 18F-FDG PET/CT in the initial staging of very high risk Ewing sarcoma in a prospective multicentric phase II study: Is there still a place for bone marrow sampling?

Ewing Sarcoma Family of Tumours (ESFT) are rare tumours, with metastatic spread at diagnosis in one out of three patients. Bone and/or bone marrow involvement strike markedly prognosis. Accurate initial staging is therefore fundamental for treatment adaptation. 18F-FDG PET/CT is the current modality for the evaluation of disease extension. The aim of this study is to assess the prospective value of FDG PET/CT compared to bone marrow cytology/biopsy (BMCB) staging in very high risk ESFT patients. Pediatric and adult patients from 15 French sarcomas referral centers with a diagnosis of extrapulmonary disseminated ESFT were prospectively included from 2017 to 2021, in the COMBINAIR3 phase II trial. This study aimed to evaluate a strategy combining dose dense induction chemotherapy, high dose consolidation and prolonged maintenance for these very high risk patients. All patients underwent baseline full body 18F-FDG PET/CT with centralized real-time imaging review and BMCB sampling at diagnosis consisting in both bone marrow cytology and biopsy (at least 2 different sites per patient). Patients management was similar wether bone spread was presenting as lytic or intra-medullarry lesion. We report here the baseline bone and bone marrow (BM) analysis. Out of 43 patients included (aged 6 to 47 years-old), 11 were positive on BMCB staging (cytology n=6, biopsy n=1, both n=4), all consistant with bone/BM extension defined on baseline 18F-FDG PET/CT: 6 had BM involvement on PET (5 of whom also had bone lesions), and 5 had bone involvement only. PET/CT identified metastatic spread to bone and/or BM in 35 patients (81%), including 24 with negative BMCB. Twenty-three had bone lesions, 11 had both bone and BM involvement and one had BM extension alone. Bone/BM involvement was confirmed either by lytic bone destruction on the CT-component or on MRI imaging. FDG PET/CT detects 3 times more bone/bone marrow lesions than bone marrow cytology/biopsy in the initial staging of very high risk Ewing Sarcoma. Our data suggest that BMCB sampling can be avoided in favor of non-invasive PET/CT staging.

P1187: END OF TREATMENT 18F FDG-PET/CT RESPONSE IS PROGNOSTIC FOR OVERALL AND PROGRESSION-FREE SURVIVAL IN PERIPHERAL T-CELL LYMPHOMA: RESULTS OF THE UK NCRI PHASE 2 RANDOMISED CHEMO-T TRIAL PET/CT SUBSTUDY

Background: The role of 18F FDG PET (PET) in peripheral T-cell lymphoma (PTCL) remains under evaluation. The UK NCRI phase 2 randomised CHEMO-T trial compared cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP) with gemcitabine, cisplatin and methylprednisolone (GEM-P) in previously untreated PTCL patients. The primary endpoint, to demonstrate a superior complete response (CR) rate for GEM-P by contrast-enhanced CT (CECT) at end of treatment (EOT) was not met. Aims: To investigate the role of PET in determining baseline bone marrow (BM) involvement in PTCL and as a prognostic tool at EOT. Methods: Patients required a baseline PET (acquired as per protocol) within 28 days of randomisation and a PET at EOT at least 28 days post chemotherapy. Site accreditation, data collation, and quality control for PET imaging was performed by the UK PET Core Lab. BM biopsy was required within 6 weeks of randomisation. PET scans were centrally reviewed at The Royal Marsden by 2 expert nuclear medicine physicians (YD and NH). Baseline BM involvement by PTCL on PET was evaluated. PET response was assessed according to the revised response criteria for malignant lymphoma and by the Deauville score (DS) 5-point scale. Where discordance existed between reviewers, a third reviewer (SC) adjudicated. EOT PET response and PET status (DS 1-3=PET-negative, DS 4-5=PET-positive) were correlated with PFS and OS. Results: Baseline PET data was available for 82/84 patients, 80/82 (98%) had FDG-avid disease (n=2 with non-avid disease (n=1 AITL, n=1 EATL) were excluded). Clinical characteristics were similar to the main trial cohort: median age=63 yrs, male=73% and high-risk IPI=23%. PTCL subtypes were AITL n=33 (41%), PTCL-NOS n=32 (40%), ALK- ALCL n=14 (18%) and EATL n=1 (1%). For 20/79 (25%) patients with biopsy-proven BM infiltration 9/19 (47%) had BM uptake on baseline PET. Of 20/80 patients (25%) with BM uptake on baseline PET, 9/20 (45%) had biopsy-confirmed infiltration. PET had a sensitivity of 47% and a specificity 81% for determination of BM involvement. EOT PET was available for 69/80, n=4 were excluded as data was acquired following a later line (n=3) or complete imaging was not retrievable (n=1); therefore 65/80 had evaluable EOT PET data. The median number of days from EOT to PET was 41. At EOT, PET response was CR n=41 (63%), partial response (PR) n=15 (23%), stable disease n=0 and progressive disease (PD) n=9 (14%); 41 (63%) were PET-negative and 24 (37%) were PET-positive. At a median follow-up of 27 months, PET-negative vs. PET-positive patients at EOT had a 2-yr OS of 72% vs. 52% [HR 0.58; 95% CI 0.24–1.41), p=0.231] and 2-yr PFS of 55% and 29% [HR 0.45 (95% CI 0.23–0.88), p=0.021] respectively. EOT PET response correlation with 2-yr OS was CR=72%, PR=67%, PD=29%; and with 2-yr PFS was CR=55%, PR=32%, PD=25%. A CR by PET (vs. PD) was associated with improved OS [HR 0.245 (95% CI 0.083–0.730), p=0.012] (Figure 1) and PFS [HR 0.265 (95% CI 0.102–0.687), p=0.006]. Adjusting for stratification parameters at randomisation (IPI risk group, PTCL subtype) PET response remained prognostic for both OS and PFS while EOT PET status (positive vs. negative) did not. CECT response remained prognostic for PFS only. Image:Summary/Conclusion: Our findings indicate that PET has insufficient sensitivity for detection of BM involvement for baseline staging. Furthermore, while both EOT CECT and PET response were prognostic for PFS and OS, only PET response remained prognostic for OS following adjustment for stratification factors suggesting it is a superior prognostic tool in PTCL.

S173: T-CELL ACTIVATION AND MYELOMA CELL KILLING CONFIRM THE MODE OF ACTION OF RG6234, A NOVEL GPRC5D T-CELL ENGAGING BISPECIFIC ANTIBODY, IN PATIENTS WITH RELAPSED/REFRACTORY MULTIPLE MYELOMA

Background: RG6234 is a novel T-cell engaging bispecific antibody targeting G protein-coupled receptor 5D (GPRC5D) with a unique 2:1 format. GPRC5D is highly expressed on multiple myeloma (MM) cells and concurrent binding of RG6234 to GPRC5D and CD3 on T cells results in immunological synapse formation and potent T-cell directed tumor cell killing. An ongoing Phase 1 dose-escalation study (NCT04557150) is investigating the safety, clinical activity, pharmacodynamics (PD), and pharmacokinetics of RG6234 monotherapy in patients (pts) with relapsed/refractory MM (RRMM). Clinical activity was observed during dose escalation, and the safety profile was manageable (Riley et al. EHA 2022). Aims: Here, we present preliminary clinical biomarker data highlighting PD effects after intravenous (IV) administration that confirm the mechanism of action and high potency of RG6234. Methods: Exploratory biomarker analyses included data from pts treated with RG6234 doses ranging from 0.006mg to 4.8mg in dose escalation. RG6234 was administered as an IV infusion under a step-up dosing regimen, reaching the target dose not later than 2 weeks after the priming dose. Peripheral biomarkers were evaluated using whole blood flow cytometry (n=28), plasma cytokine Protein Simple ELLA (n=33), and plasma sBCMA Protein Simple ELLA (n=26). MM cells were assessed at baseline and on-treatment by bone marrow (BM) aspirate flow cytometry and by BM biopsy CD138/CD8 immunohistochemistry. Informed consent was obtained from participating pts. The clinical cut-off date for the current analysis was January 31, 2022. Results: PD changes were observed in peripheral blood at all tested doses. Cytokines (IFNg, TNFa, CXCL10, IL6, IL10, IL2, IL8) and sCD25 peaked at 4 to 24 hours (h) following the first administration, while cytokine peak magnitudes decreased at subsequent administrations. Cytokine release was followed by transient reduction of circulating T cells at 4 h after infusion, with partial recovery of peripheral T-cell counts by Day 8 after first administration. Elevation of sCD25 and IFNg in plasma (~3.2 and 33 median fold change from baseline, respectively) together with increase in T-cell proliferation (~4 median fold increase of Ki67+CD8+ T-cells) within 72 h post first infusion indicated T-cell activation. Analysis of a limited number of paired baseline and on-treatment BM biopsies (n=13) revealed that the density of CD8+ tumor-infiltrating T cells increased upon treatment in responders, indicating T-cell recruitment towards the tumor. RG6234 induced rapid depletion of MM cells, as demonstrated by a decrease of sBCMA in the plasma of responding pts already 8 days after the first administration (median 33.5% reduction from baseline in responding pts; n=15). Moreover, at the end of Cycle 1, the majority of pts (14/15) had <1% of MM cells in BM based on flow cytometry readout. GPRC5D expression was detected at baseline in all pts with evaluable bone marrow aspirate and >20 detectable MM cells (n=16). Updated exploratory biomarker data will be presented. Summary/Conclusion: Cytokine release, T-cell activation, BM infiltration, and MM cell depletion are early PD changes seen after treatment with RG6234 and precede clinical responses. These PD changes indicate that RG6234 leads to T-cell engagement in the BM of pts with RRMM and clearly demonstrate rapid and effective T-cell mediated anti-MM activity.

Autologous bone marrow mononuclear cells in the treatment of chronic limb-threatening ischaemia: a proof-of-concept trial

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): 1. Iniciativa Andaluza en Terapias Avanzadas 2. Fundación Progreso y Salud Background Chronic limb threatening ischaemia (CLTI) is a debilitating condition often leading to gangrene which necessitates amputation. Endovascular or surgical interventions remain the standard treatment, however, not all patients are suitable for such procedures. The aim of cell-based therapies is to harvest progenitor cells either from the patient (i.e., autologous) or other sources and re-administer them at a higher concentration near/at the ischemic site(s) to potentiate vasculogenesis. Aim The objective of this trial was to assess the efficacy, safety, and feasibility of treating CLTI with autologous bone marrow mononuclear cells (BM-MNC). Methods This multicentre, phase II, open-label, randomized clinical trial conducted between 2009 and 2011 consisted of adult diabetic patients with CLTI Rutherford grade II or III of at least one lower limb who were not suitable for surgical revascularization. Sixty eligible patients were randomly assigned to one of three treatment groups (1x108, or 5x108, or 1x109 BM-MNCs) or to the control group (standard of care treatment). The cell-product was prepared from the baseline bone marrow aspirate of the treated patients and injected intra-arterially proximal to the vessel occlusion under general anaesthesia &amp;lt;72 hours after bone marrow aspiration. The control patients did not undergo bone marrow aspiration. Ulcer healing and amputation variables were evaluated in all patients at baseline and months 1, 3, 6, 9 and 12. Results The sample demographics were similar in each arm. A total of 50 males and 10 females were enrolled into the trial, with mean age of 63.9 (SD=9.4) years, and mean body mass index of 27.8 Kg/m2 (SD=4.1). The average years living with diabetes was 18.6 years, and time since diagnosis of CLTI was 0.78 years (SD: 1.12 years). A clinically meaningful treatment effect was observable at 6 months, and at 12 months baseline ulcers in 75% of treated patients were completely healed, compared to 14% of control patients (P=0.0142). Furthermore, the ulcers of the treated patients were on average 19.66 mm smaller than those of the control patients (P&amp;lt;0.0001). These results corresponded to angiographical outcomes where vasculogenesis was observed in approximately half of the treated patients who improved in Rutherford Grade. There were no differences in amputation rates across arms. No pertinent covariates which might have impacted the outcomes were identified. No treatment-associated adverse events occurred in the trial. Conclusion Autologous BM-MNC is an effective therapeutic alternative in patients unsuitable for surgical or endovascular revascularization.

Impact of bone marrow involvement in patients with peripheral T-cell lymphoma undergoing autologous stem cell transplant.

7550 Background: Nodal-based T-cell lymphomas (PTCL) are treated with induction therapy and consideration for autotransplant (autoSCT) in first remission. The impact of bone marrow (BM) involvement at diagnosis and at autoSCT is unclear. Methods: We performed a retrospective review of consecutive patients with PTCL-NOS, AITL, and ALCL who received autoSCT in first remission at Memorial Sloan Kettering Cancer Center from 1997-2021. For BM involvement at baseline, patients were classified as positive (≥5% by histology), any involvement (by histology and/or at least 1 high-sensitivity [HS] assay, referring to flow or clonal TCR gene rearrangement), or negative (no involvement by histology and at least 1 negative HS assay). Patients with no baseline BM biopsy were excluded. At end of therapy (EOT, after induction but prior to autoSCT), BM involvement was considered positive (≥5% by histology), minimal residual disease positive (MRD+, no histological involvement but at least 1 positive HS assay), and MRD- (no histological involvement and at least 1 negative HS assay). Patients with no EOT BM but negative baseline BM were included as a separate cohort. Patients with no baseline BM and no EOT BM were excluded, as were those with baseline BM involvement and no EOT BM. The Kaplan-Meier method was used to estimate survival and compared using log-rank tests. Results: A total of 135 patients were included. Median follow-up after autoSCT for survivors was 56 months. The 5-year PFS/OS for the entire cohort was 45% and 65%, respectively. By histology, 5-year PFS/OS for PTCL-NOS (N = 27), AITL (N = 78), ALK+ (N = 8) and ALK- (N = 21) ALCL was 36%, 37%, 75%, 74% (p = 0.005), and 51%, 59%, 100%, 85% (p = 0.01). Among those with adequate baseline BM evaluation (N = 98), 31 were positive, 52 had any involvement, and 44 were negative. Five-year PFS and OS in the positive, any involvement, and negative groups was 46%, 42%, 44% (p = 0.82), and 63%, 61%, 74% (p = 0.27). Of those with adequate EOT BM evaluation (N = 72), 1 was positive, 17 were MRD+, and 43 were MRD-; 32 patients had no EOT BM but negative baseline BM. Five-year PFS and OS by the EOT positive, MRD+, MRD-, and no EOT BM but negative baseline groups was 0%, 37%, 45%, 45% (p = 0.86), and 0%, 92%, 59%, 71% (p = 0.39). Of the 17 patients with MRD+ EOT BM, 14 (82%) had AITL. Two-year PFS/OS in the AITL only cohort by EOT BM was 0%, 54%, 48%, 33%, and 0%, 90%, 75%, 72%, for the positive, MRD+, MRD-, and no EOT BM but negative baseline groups (PFS: p = 0.4; OS: p = 0.3). Conclusions: In patients treated with upfront induction and autoSCT in first remission, neither BM involvement at diagnosis nor the presence of MRD at the time of autoSCT resulted in worse survival outcomes compared to those with no BM involvement. For patients with PTCL-NOS, AITL, or ALCL in first remission, baseline BM involvement or pre-autoSCT BM MRD+ should not dissuade use of autoSCT consolidation.

Inhibition of MDM2 Improves the Therapeutic Effect of Hypomethylating Agents in Myelodysplastic Syndromes (MDS) and Chronic Myelomonocytic Leukemia (CMML)

Hypomethylating agents (HMA) are the current standard care for MDS and CMML. However, a large proportion of patients experience HMA treatment failure that is associated with poor prognosis. Novel treatments are urgently needed for these diseases. We performed next generation sequencing (NGS) based mutation profiling that targeted the 81 most frequently mutated genes in baseline bone marrow (BM) mononuclear cells (MNCs) from patients with MDS and CMML (N=83) prior to HMA treatment. Analysis of impact of the mutations on outcomes of HMA treatment indicated that patients with TP53 mutations (N=22) had significantly worse overall survival (HR = 3.29; P < 0.05; q < 0.05). This result is consistent with previous reports and suggests that strengthening the activity of wild type (WT) TP53, through strategies such as inhibition of TP53 negative regulator MDM2, may improve therapeutic efficacy of HMAs in patients with MDS and CMML.To test this hypothesis, we evaluated in vitro the effects of the combination of the MDM2 inhibitor DS-3032b and azacytidine (AZA). Due to the dearth of MDS or CMML cell lines, initial analysis was performed in the TP53 WT AML cell line MOLM13. Results indicated that DS-3032b and AZA combination induced a synergistic decrease in cell survival (coefficient of drug interaction=0.65), accompanied with increased apoptosis and CDKN1A1 (P21) RNA expression. No combination survival effect was observed in the TP53 mutant AML cell lines SKM1 or TF1.We next evaluated in vivo combination therapeutic effects of the MDM2 inhibitor DS-5272 and AZA in a Tet2-knockout (KO) (Tet2flox/flox/Vav-Cre) mouse model. Prior work indicated that Tet2-KO mice had an MDS/CMML-like phenotype and a persistent long-term (LT) BM repopulating activity that was resistant to AZA. DS-5272 and AZA were administered to mice sequentially: DS-5272 (50 mg/kg) was administered orally for 5 days, followed by daily AZA (2.5 mg/kg, i.p.) for a 7 days. DS-5272 was also administered on the 1st and 3rd days during AZA treatment. After a 2-week gap, the treatment cycle was repeated once. Following the combination treatment, Tet2-KO mice showed significantly reduced monocytosis (P<0.05) and increased platelet counts (P<0.001) in peripheral blood (PB), and significant reductions in Gr1+/CD11b1+ myeloid cells (P<0.001), common myeloid progenitors (CMPs) (P<0.005), and Lin-/Sca1+/c-Kit1+ cells (LSKs) (P<0.01) in BM. Next, we evaluated the impact of treatment on LT BM repopulation activity. CD45.2+ BM cells isolated from drug-treated Tet2-KO mice were mixed with BM cells from CD45.1 WT mice and then transplanted into lethally irradiated CD45.1 WT recipient mice. Significantly lower (P<0.05) CD45.2 chimerism was observed in PB of the recipients transplanted by BM cells from DS-5272 and AZA combination treated Tet2-KO mice compared to recipients that received cells from vehicle control and mono-agent treated Tet2-KO mice, starting from 4 months post-transplantation (Fig.1A). Lower CD45.2 chimerism was also observed in the BM LSK population (P<0.001) of the same recipients at the endpoint of 6 months post-transplantation.To study the molecular mechanisms underlying the combinational therapeutic effects of the MDM2 inhibitor and AZA observed in the Tet2-KO mice, we performed RNA-seq on BM LSK cells isolated from drug-treated mice. Compared to LSKs from vehicle control mice, over 800 genes with significantly altered RNA expression (>1.5 fold; FDR<0.05) were identified in the LSKs from DS-5272 and AZA combination treated Tet2-KO mice, whereas 110 and 476 genes with altered RNA expression were identified in the LSKs of DS-5272 or AZA treated Tet2-KO mice respectively. REACTOME pathway analysis identified 263 pathways that were significantly (FDR<0.25) and uniquely activated in the BM LSKs from mice treated with DS-5272 and AZA combination. Many of these pathways were associated with TP53 stability, TP53 activity, and TP53 regulated apoptosis and cell cycle (Fig.1B), suggesting a coordination between MDM2 inhibition and HMA treatment to activate TP53 in BM HSPCs.In conclusion, our work provides proof-of-concept evidence that combining an MDM2 inhibitor with AZA can improve the therapeutic efficacy of AZA in MDS and CMML, through mechanisms including synergistic activation of TP53 in BM HSPCs and inhibition of LT BM repopulating activity. This concept should be further evaluated through pre-clinical studies and clinical trials. [Display omitted] DisclosuresWei: Daiichi Sanko: Research Funding. Daver: Amgen: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Hanmi: Research Funding; Trillium: Consultancy, Research Funding; Glycomimetics: Research Funding; Genentech: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; Novimmune: Research Funding; FATE Therapeutics: Research Funding; Trovagene: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding.

Transcriptomic Signitures of Azacitidine (AZA) and Decitabine (DAC) Resistance in MDS and CMML

INTRODUCTION: Myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML) are heterogeneous myeloid neoplastic disorders characterized by ineffective hematopoiesis leading to cytopenias and increased risk of transformation to acute myeloid leukemia (AML) . The hypomethylating agents (HMA) azacitidine (AZA) and decitabine (DAC) improve the natural history of MDS and CMML patients (Fenaux et al 2009). However, over half of the cases experience primary failure defined by a lack of response to HMA treatment which is associated with poor prognosis and a median survival of 4-6 months (Garcia-Manero et al. 2016, Jabbour et al. 2010). The highly heterogeneous pathophysiology of myeloid neoplasms and poorly understood mechanisms underlying therapeutic action of HMAs pose substantial challenges in understanding the biology of HMA failure in MDS and CMML.METHODS: We established a cohort of baseline bone marrow (BM) cells that were collected from 17 CMML and 34 MDS patients with excessive blasts (MDS-EB) prior to their HMA based therapies (Figure 1). RNA-Seq based transcriptomic analysis was performed in CD34+ BM hematopoietic stem and progenitor cells (HSPCs) of patients, known to be the cellular origin of these diseases, to identify biological signatures of primary HMA resistance.RESULTS: Similar to the recent reports regarding the lack of common gene expression signatures in HMA resistant AML cell lines (Leung et al. 2019) , RNA-Seq in patient cohort detected fewer than 0.5% of the total number of differentially expressed genes in non-responders in common for both AZA and DAC. Of note, all the AZA and a large portion of DAC associated genes with down-regulations in non-responders encode immunoglobulins, which is consistent with several recent findings indicating impaired differentiation B cells in association with unfavorable outcomes in MDS and CMML (Ribeiro et al. 2006 and Kahn et al. 2015). We performed flow cytometry analysis in BM cells available for 13 patients prior to start of HMA treatments (5 non-responders and 8 responders), and detected that HMA non-responders had a strong tendency (P=0.07) of decreased baseline frequencies of B cells in their BM than HMA responders.GSEA analysis based on leading edge genes identified over 200 and 300 biological signaling pathways to be associated with AZA and DAC failure respectively, with 78 pathways commonly correlated with treatment failure of both drugs (28 up-regulated and 60 down-regulated, Table 1). Clustering of these commonly altered pathways based on biological functions revealed that most of them are known to have a role in MDS and CMML pathogenesis and/ or drug resistance. For instance, neurotransmitter, olfactory pathways, and associated G-protein coupled receptor signals was recently reported to play a role in regulating the maintenance and differentiation of BM HSPCs (Shao et al. 2021 and Shim et al. 2013), whereas cell junction signaling that involves integrins and increased MAP2K-MAPK signaling were also reported to be associated with AZA resistance in MDS and CMML (Unnikrishnan et al. 2017).Among commonly down-regulated biological pathways in non-responders of AZA and DAC, there were clusters of immunoglobulin-associated signals, protein translation regulatory pathways that involve ribosomal proteins, cell cycle signaling, respiratory chain, and Golgi transport signals. Decreased expression of ribosomal proteins and related impairment of ribosomal functions were known mechanism in MDS and CMML development (Ebert et al. 2008 and Schneider et al. 2016). Furthermore, decreased respiratory chain and Golgi transport signals were also identified by transcriptomic investigation in the DAC resistant TF1-RES cell lines.In addition to the commonly altered signals for both AZA and DAC resistance, innate immune signaling pathways including interferon and toll-like receptor signals were significantly up-regulated in DAC non-responders but down-regulated in AZA non-responders.CONCLUSIONS: In this study, the transcriptomic data between responders and non-responders to AZA and DAC were investigated separately, thereby drug-specific as well as the common biomarkers associated with treatment failures of both drugs could be identified. The relatively low proportion of genes and pathways shared by AZA and DAC non-responders suggest the difference underlying biological mechanisms of AZA and DAC failure. [Display omitted] DisclosuresSasaki: Novartis: Consultancy, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees. Wei: Daiichi Sanko: Research Funding.

Assessment of Next Generation Sequencing Approaches for the Cytogenetic and Molecular Evaluation of Acute Myeloid Leukemia

Background:Genomic evaluation of structural and molecular alterations is essential for the classification and risk stratification of patients with acute myeloid leukemia (AML). Cytogenetics (CG) has traditionally been used for the identification of large structural or copy number changes and molecular studies for small sequence changes. Rapid technical advances and decreased sequencing (seq) costs have made whole-genome sequencing (WGS) more feasible and recent efforts have suggested it can match the analytic performance of traditional CG while providing additional prognostic information. However, the use of WGS in the clinic is still in its infancy and questions remain regarding the utility of many factors including seq depth, structural events not identifiable by traditional CG, normal samples, AML enrichment, paired RNA-seq, and single-cell DNA-seq.Methods:Baseline bone marrow (BM) samples from 10 AML patients underwent evaluation using standard clinical CG and targeted next generation seq tests. Additionally, samples were extensively characterized using: 200X WGS (bulk and enriched BM), 50X germline WGS (buccal swab and remission blood), 50X RNA-seq, targeted error-corrected (EC) DNA-seq, and single-cell DNA-seq with oligonucleotide-conjugated antibodies (scDNA-seq+ab).Results:The AML patients analyzed had a mean age of 71 (30-81) and a range of BM blast percentage by clinical flow cytometry (0.4-33%). Standard clinical assessment revealed 14 CG abnormalities and 20 mutations across all patients. 50X WGS of the bulk BM utilizing previously published conditions (PMID:33704937) successfully identified 89% of the alterations. Increasing the WGS depth to 100X recovered 2 additional abnormalities, increasing the capture rate to 94%.Enrichment of AML using the primary cell surface marker prior to WGS achieved a 94% capture rate at only 50X depth, with a depth of only 10X required for the CG abnormalities. Integration of 50X WGS on buccal swab samples reduced the large number of structural variant calls and private mutations without the need for aggressive filtering conditions required for tumor-only samples. However, this also resulted in the removal of a few true mutations due to buccal contamination with immune cells. 50X WGS on remission blood samples from 2 patients mitigated this problem.Next, we sought to determine what additional information WGS could provide that was missed by standard CG (>5Mb) and seq (>5% variant allele fraction, VAF) analyses. Firstly, 3 of the deletions reported by CG were found to be complex translocation events, resulting in different losses and gains than anticipated. Most importantly, decreasing the CNV size threshold (<5Mb) and utilizing SNP data to identify copy neutral loss of heterozygosity (LOH) identified 7 new events in bulk BM and 2 new events in enriched BM. This information provided important prognostic information, including 3 newly identified structural alternations in a patient with a CG-reported normal karyotype, multiple small deletions in critical regions (e.g. within 5q, 7q), and LOH which in combination with molecular data revealed a biallelic loss of important genes (including TP53, EZH2).Targeted EC DNA-seq was used to detect of variants <5% VAF and identified an additional 23 variants beyond clinical capture sequencing. 50X RNA-seq with integrated WGS DNA/RNA calling was able to validate the mutations and translocation fusion genes reported by 50X WGS, while also capturing an additional 4 variants found by EC DNA-seq.Finally, personalized scDNA-seq+ab provided further resolution of each patient's AML through confirmation of new structural and mutational findings, identification of mutations associated with clonal hematopoiesis versus AML, and definition of AML clonal structure (Figure 1).Conclusions:We confirmed that 50X WGS can recapitulate standard clinical CG and mutational profiling in AML patients while providing improved resolution. Deeper seq, AML pre-enrichment, and integrated RNA-seq further aided in identifying low level events. We also demonstrated that WGS can identify additional important structural events missed by CG. Finally, personalized scDNA-seq+ab was able to define clonal architecture important for prognostic and residual disease tracking. Together, these results provide a framework for future integration of WGS into the clinic and personalized patient care. [Display omitted] DisclosuresSciambi: Mission Bio Inc.: Current Employment. Durruthy-Durruthy: Mission Bio Inc.: Current Employment. Hourigan: Sellas: Research Funding.

A Phase 1 Trial of Adct-602, a CD22 Targeting Antibody Drug Conjugate Bound to PBD Toxin in Adult Patients with Relapsed or Refractory CD22+ B-Cell Acute Lymphoblastic Leukemia

A Phase 1 Trial of Adct-602, a CD22 Targeting Antibody Drug Conjugate Bound to PBD Toxin in Adult Patients with Relapsed or Refractory CD22+ B-Cell Acute Lymphoblastic Leukemia

Molecular Responses Are Observed across Mutational Spectrum in Treatment-Naïve Higher-Risk Myelodysplastic Syndrome Patients Treated with Venetoclax Plus Azacitidine

Molecular Responses Are Observed across Mutational Spectrum in Treatment-Naïve Higher-Risk Myelodysplastic Syndrome Patients Treated with Venetoclax Plus Azacitidine

Disease-Modifying Potential of BET Inhibitor Pelabresib (CPI-0610) As Demonstrated By Improvements in Bone Marrow Function and Clinical Activity in Patients with Myelofibrosis - Preliminary Data

Disease-Modifying Potential of BET Inhibitor Pelabresib (CPI-0610) As Demonstrated By Improvements in Bone Marrow Function and Clinical Activity in Patients with Myelofibrosis - Preliminary Data

A Pilot Study of the Anti-SLAMF7 Monoclonal Antibody, Elotuzumab, in Myelofibrosis

A Pilot Study of the Anti-SLAMF7 Monoclonal Antibody, Elotuzumab, in Myelofibrosis

Predictive Biomarkers of Response to the Polo-like Kinase 1 (PLK1) Inhibitor, Onvansertib, in Combination with Decitabine in Relapsed or Refractory Acute Myeloid Leukemia (R/R AML)

Predictive Biomarkers of Response to the Polo-like Kinase 1 (PLK1) Inhibitor, Onvansertib, in Combination with Decitabine in Relapsed or Refractory Acute Myeloid Leukemia (R/R AML)

Efficacy and Safety of Ciltacabtagene Autoleucel in Patients With Relapsed/Refractory Multiple Myeloma: CARTITUDE-1 Subgroup Analysis

Efficacy and Safety of Ciltacabtagene Autoleucel in Patients With Relapsed/Refractory Multiple Myeloma: CARTITUDE-1 Subgroup Analysis

Clinical Characteristics Associated with Venous Thromboembolism in Patients with Non-APL Acute Myeloid Leukemia

INTRODUCTIONVenous thromboembolism (VTE) is an important complication of many cancers. Although more widely recognized in solid tumors, VTE is still an appreciable cause of morbidity and mortality among patients with hematologic malignancies. For example, acute promyelocytic leukemia (APL) is a well-recognized risk factor for disseminated intravascular coagulation (DIC), which can lead to thrombosis. Patients with non-APL AML are also at increased risk for VTE, though the exact mechanisms are currently unclear. Thus, we sought to explore how patient demographics, comorbidities, hematologic factors, coagulation parameters, and cytogenetic and molecular profiles impact the incidence of VTE in patients with non-APL AML. METHODSThis was a retrospective observational case-control study of 120 non-APL AML patients treated at the University of Wisconsin-Madison. The electronic health record was manually reviewed for extraction of the relevant clinical information. Coagulation parameters assessed included INR, PTT, fibrinogen, D-dimer, and fibrin monomer. Coagulation data were collected both at diagnosis and during the first 7 days of induction, if applicable. Cytogenetics was categorized based on the presence of a normal karyotype or not. Genomic data were subdivided into eight different functional categories of genes that are commonly mutated in AML. Other factors that could potentially increase the risk of thrombosis were also analyzed, including age, sex, BMI, baseline blood counts, baseline bone marrow blast percentage, previous history of VTE, use of antifibrinolytic agents, and whether blood products were transfused during the early treatment period. The variables of interest between VTE cases and non-VTE cases were compared using the nonparametric Wilcoxon rank sum test. RESULTSAcross the entire cohort (n=120), VTE developed in 25 patients (20.8%) and did not develop in 95 patients (79.2%). Table 1 and Table 2 show comparisons between VTE cases and patients without VTE for both quantitative and categorical variables. Median INR values at diagnosis and across the first 7 days of induction tended to be lower in patients with VTE and reached significance on days 3-5 (p=0.032 for INR-Day 3, p=0.046 for INR-Day 4, p=0.014 for INR-Day 5). Patients with VTE had a median BMI of 30, while patients without VTE had a median BMI of 28, which approached statistical significance (p=0.055). 8% of patients with VTE (2/25) had a history of VTE prior to the diagnosis of AML, while 3% without VTE (3/95) had a history of previous VTE (OR 2.7, p=0.281). Mutation in genes involved in DNA methylation also conferred an increased risk of VTE, with the association approaching statistical significance (p=0.083). There were no other variables that were significantly different between the two groups. CONCLUSIONSIn this cohort of patients with non-APL AML, there was a trend towards lower INR correlating with an increased incidence of VTE. Additionally, higher BMI, previous history of VTE, and mutation in DNA methylation genes were associated with increased incidence of VTE, though these trends did not reach statistical significance. The pathophysiology of VTE in this setting is likely complex and multifactorial. The shorter INR in those who developed VTE suggests a mechanism independent of the development of DIC, which is distinct from APL. The finding that obesity and personal history of VTE, both known risk factors for thrombosis, were associated with an increased incidence of VTE is also consistent with a non-DIC mechanism. Mutations in DNA methylation genes may have contributed to increased risk of VTE in this cohort; while this association is compelling, further studies with larger sample sizes are needed to confirm this finding. This study was limited by small sample size and missing data, especially regarding available data on coagulation tests. However, this analysis uncovers interesting associations that shed light on the pathophysiology of VTE in AML. More research is needed to further elucidate risk factors for VTE in order to provide optimal supportive care for this patient population. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

An Australasian Leukemia Lymphoma Group (ALLG) Phase 2 Study to Investigate Novel Triplets to Extend Remission with Venetoclax in Elderly (INTERVENE) Acute Myeloid Leukemia

An Australasian Leukemia Lymphoma Group (ALLG) Phase 2 Study to Investigate Novel Triplets to Extend Remission with Venetoclax in Elderly (INTERVENE) Acute Myeloid Leukemia