Blast Reduction Research Articles

Dose Escalation of HLA-A2-WT1 CD3 T-Cell Bispecific Antibody in a Phase I Study in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML)

Background: RO7283420 (RG6007) is a 2+1 TCR-like (TCR-L) T-cell bispecific (TCB) antibody targeting CD3 and the RMFPNAPYL peptide of Wilms Tumor 1 (WT1) protein presented by the major histocompatibility complex-I HLA-A*02 on acute myeloid leukemia (AML) blasts and other antigen presenting cells. The pre-clinical evaluation of RO7283420 in our in vivo humanized AML xenografts and ex vivo AML co-culture models showed strong T-cell mediated AML cell killing (Augsberger C, et al. Blood 2021). A Phase 1 dose-escalation (DE) study (NCT04580121) evaluated the safety, tolerability, pharmacokinetics, anti-drug antibodies (ADAs), and anti-leukemic activity of RO7283420 in patients with relapsed/refractory (R/R) AML. Methods: In this open-label, multi-center study, DE was performed using a 3+3 design. Patients received RO7283420 every 3 weeks (Q3W, n=46), or every week (QW, n=4) as intravenous (IV) infusions. Preliminary anti-leukemic activity included response assessment according to European Leukemia Net (ELN) response categories (adapted from Döhner H, et al. Blood 2017). Results: As of 13 April 2023, 50 HLA-A2+ R/R AML patients received at least one dose of RO7283420. Patients had a median age of 65.5 years (range 35-84), presented with ECOG of 0 (56%) or 1 (38%) or 2 (6%), and 58% were male. Median prior line of therapy was 2 (range 1-5). Overall, 58% of patients had relapsed and 42% had primary refractory disease. According to the ELN 2017 risk stratification, patients were of adverse (48%), intermediate (38%) or favorable (8%) risk category, for 6% of patients the risk category missing. The most common genetic abnormalities reported were RUNX1 (21%), ASXL1 (17%), TP53 (10.6%), FLT3-ITD (6.4%) and NPM1 (6.4%) of the 47 patients tested. Median bone marrow blast percentage at baseline was 35% (range 3-90%), while the median of circulating blast was 17% (range 0-88%). Study patients received RO7283420 IV at 13 different dose levels, ranging from a Minimum Anticipated Biological Effect Level (MABEL) of 0.15 mg (flat) to 18 mg Q3W (with a preceding weekly 1/3 mg ‘double step-up’ during Cycle 1) and one QW dose level with 9 mg preceded by a 1/3 mg step-up. Maximum tolerated dose was reached at 1/3/12 mg double step-up Q3W. Explored alternative QW schedule was not tolerable at 1/3/9 mg. The most common (≥20%) adverse events (AEs) were cytokine release syndrome (CRS) occurring in 34 (68%), pneumonia 14 (28%), pyrexia 13 (26%), febrile neutropenia 13 (26%), hyperglycemia 12 (24%), hypokalemia 11 (22%), and nausea 10 (20%) of patients. Eight dose limiting toxicities (DLTs) were reported: five G3 CRS (at 1/3, 2/12, 1/6/12 mg dose levels), G3 stomatitis (at 1/3/12 mg), G3 myositis (at 1/3/18 mg), and G4 thrombocytopenia (at 1/3/18 mg). Eleven patients (22%) experienced Grade 5 AEs with pneumonia, sepsis, and hemophagocytic lymphohistiocytosis (HLH) reported in >1 patient; all Grade 5 events were considered unrelated to RO728342 except 1 (at 1/3/9 mg) of 2 HLH events. IV PK has been overall dose-linear and characterized by a terminal half-life of 29 to 84 hours and a clearance of 58 to 92 mL/h. Preliminary ADA incidence within the study population was 19%. In the dose ranges tested, a trend for study drug exposure-dependent blast reduction was observed in blood, while a clear exposure-response relationship could not be established with BM blast reduction. Furthermore, our preliminary pharmacodynamic analysis identified expansion of naive and memory CD8 T cells in blood and activated CD8+ T cells in bone marrow, in line with the expected mode of action (MoA) of RO7283420. Preliminary efficacy signals were observed with 3 complete responses (CR), including 1 CR with incomplete blood count recovery. Conclusions: RO7283420 is the first TCR-L TCB antibody evaluated in AML. We observed pharmacodynamic evidence of T-cell activation and expansion in the clinic, in line with the expected MoA of TCBs, however, at the explored doses, no clear exposure-response relationship and only a modest clinical activity were observed. The safety profile was shown to be consistent with the other TCBs and R/R AML population. Based on the totality of data, the study was discontinued.

Preclinical and Clinical Evidence for Erythroid-Stimulating Activity of RVU120 CDK8/19 Inhibitor in AML and MDS

Introduction: RVU120 is an orally bioavailable small molecule inhibitor targeting mediator complex kinases CDK8 and its paralog CDK19. Preclinical results indicated that treatment with RVU120 could reduce the viability of AML cells, in particular those positive for NPM1 and DNMT3A mutations. Further studies also indicated that RVU120 induces erythroid differentiation of malignant stem cells isolated from AML and MDS patients, likely by the induction of STAT5-GATA1-dependent transcription. The first signs of clinical efficacy have been observed in the ongoing Phase 1 dose escalation study of RVU120 in AML and HR-MDS patients. The presented work provides the preclinical rationale and growing clinical evidence that in addition to previously reported blast reduction, RVU120 has also strong erythropoiesis stimulating activity that may be useful as a potential therapeutic strategy for MDS. Methods: RVU120-induced erythroid differentiation was studied in primary malignant stem cells from MDS patients and in a stem cell model derived from cord blood cells transformed by TLS-ERG fusion. Erythroid differentiation was tracked by flow cytometry, chromatin status, and transcriptomic changes using RNAseq, ATACseq and ChIPseq. CLI120-001 study (NCT04021368) is a phase 1 dose escalation study of RVU120 in patients with relapsed/refractory AML and HR-MDS which is currently ongoing. Flow cytometry for erythroid differentiation markers, NGS myeloid panel and bulk RNAseq were performed in all patients enrolled after September 2021. Results: At the time of the abstract submission, within 24 evaluable patients' erythroid improvement was reported in 1 patient with HR-MDS, 3 patients with AML MRC, and 1 patient with AML secondary to MF. Interestingly, in these cases, erythroid improvement was observed independently of significant blast reduction, at doses from 25 mg to 135 mg every other day in 3 weeks cycles. Transient induction of erythroid differentiation markers CD71 and/or CD235a was confirmed in 3 additional transfusion-dependent patients treated with RVU120. Bulk RNA-seq confirmed broad transcriptomic changes in BM of selected patients after treatment compared to the pre-dose baseline levels. Robust induction of genes involved in erythroblast differentiation and hemoglobin metabolism genes was confirmed in 2 AML-MRC and 2 AML patients. These changes correlated with the repression of major pro-inflammatory pathways, including hallmark interferon gamma and TNF/NFKB response genes and repression of TGFβ pathway genes. Molecular and flow cytometry changes observed in patients were consistent with the erythroid commitment and sequential induction of erythroid differentiation markers in cultured CD34+ malignant stem cells isolated from MDS and AML-MRC patients treated with RVU120 and other chemically non-related CDK8 inhibitors. Conclusions: The presented results provide clinical and preclinical evidence for RVU120 as a candidate for a novel erythroid stimulating agent. Treatment with RVU120 could be a promising addition to the current treatment options for patients with lower-risk MDS who are transfusion-dependent and failing first-line therapies.

Preliminary Results from a Phase 1 Dose Escalation Study of FHD-286, a Novel BRG1/BRM (SMARCA4/SMARCA2) Inhibitor, Administered As an Oral Monotherapy in Patients with Advanced Hematologic Malignancies

The BRG/Brahma-associated factors (BAF) family of chromatin remodeling complexes (also referred to as the mSWI/SNF complex) regulates the chromatin landscape of the genome. Through its adenosine triphosphate (ATP)-dependent chromatin remodeling activity, BAF complexes regulate the accessibility of gene-control elements, allowing for the binding of transcription factors. Thus, BAF is a major regulator of lineage- and disease-specific transcriptional programs. FHD-286 is a first-in-class, orally administered compound that potently and selectively inhibits the ATPase components of the BAF complexes, SMARCA4 and SMARCA2 (also called BRG1 and BRM, respectively). In preclinical models, acute myeloid leukemia (AML) cell lines were highly sensitive to BAF inhibition. FHD-286-C-002 (NCT04891757) is a multicenter, open-label, Phase 1 dose escalation study designed to determine the safety, tolerability, dose-limiting toxicities (DLTs), and maximum tolerated dose and/or the recommended phase 2 dose(s), as well as to evaluate the preliminary clinical activity of FHD-286, in patients with advanced hematologic malignancies. Patients with relapsed or refractory (R/R) AML or myelodysplastic syndrome (MDS) failing all available standard therapies were eligible to receive FHD-286 doses ranging from 2.5 mg once daily (QD) to 10 mg QD on a continuous dosing regimen. Patients had regularly scheduled assessments to evaluate safety, pharmacokinetics (PK), pharmacodynamics, preliminary clinical activity, and exploratory biomarkers. As of 02 Aug 2022, 40 patients with a median age of 65.5 years (range 25 to 84) with R/R AML (36 patients) or MDS (4 patients) had received at least 1 dose of FHD-286. 67.5% of patients had received ≥3 prior lines of therapy for AML/MDS/other antecedent hematologic disorder, with 22.5% having received ≥5 prior lines. 32.5% of patients had prior hematopoietic stem cell transplant. 65% of patients had adverse risk genetics by 2017 ELN recommendations. 85% of patients experienced a treatment-related adverse event (TRAE) of any grade; the most common (≥20% of patients) were dry mouth (27.5%), increased blood bilirubin (22.5%), and alanine aminotransferase (ALT) increased and rash (20% each). 50% of patients experienced a Grade ≥3 TRAE, the most common of which was increased blood bilirubin (12.5%); stomatitis, ALT increased, differentiation syndrome (DS), and hypocalcemia occurred in 7.5% (each). 2 DLTs were reported: Grade 3 hyperbilirubinemia in 1 patient receiving 5 mg QD and Grade 3 muscular weakness in 1 patient receiving 10 mg QD. Treatment-related DS of any grade was investigator-reported in 4 patients (10%). An independent adjudication committee determined that the rate of suspected DS was 15% (6 patients). 16 patients (15 AML; 1 MDS) had a best overall response of stable disease. Markers of myeloid differentiation with neutrophil recovery and reductions in bone marrow and/or peripheral blasts have been observed in a subset of patients in the study who had a broad range of cytogenetic backgrounds, including patients with enhancer-driven leukemias such as MECOM and KMT2A. Preliminary PK analysis indicates that FHD-286 appears to have a long half-life, at a minimum of >24 hours, and that plasma concentrations of FHD-286 increase with increasing dose. Exploratory flow cytometry assessment of markers of differentiation, hematopoietic stem cell identity, and apoptosis suggested dose-dependent target engagement. Additionally, exploratory sequencing analysis on bone marrow blasts revealed comprehensive impacts on AML-specific expression pathways and stemness genes in response to FHD-286. An exposure-response analysis using the percentage of peripheral blasts showed a trend toward lower blast count with higher FHD-286 area-under-the-curve. Enrollment into the single-agent dose escalation phase of the study is complete. Based on nonclinical, translational, and single-agent clinical data, FHD-286 in combination with decitabine or low-dose cytarabine is being evaluated in the combination dose escalation phase of the study.

Uproleselan Added to Cladribine Plus Low Dose Cytarabine (LDAC) in Patients with Treated Secondary Acute Myeloid Leukemia (TS-AML)

AML arising from HMA-treated myeloid disorders, also known as “treated-secondary AML” (ts-AML) is associated with an adverse prognosis (Complete Remission [CR] rates 15-30% and median Overall Survival [OS] 6-10 months). E-selectin, a marker of cell survival and resistance to chemotherapy, is highly expressed in the leukemic microenvironment. Exposure of leukemic blasts to HMAs has been shown to increase its expression. Uproleselan is an e-selectin antagonist that has demonstrated antileukemic activity in AML. We sought to study the combination of low-intensity chemotherapy with Cladribine + LDAC (CLAD/LDAC) with uproleselan to overcome local and microenvironmental resistance. This Phase Ib/II clinical trial (NCT04848974) evaluate the safety, tolerability, and efficacy of Uproleselan added to Cladribine and LDAC. A 3+3 dose-escalation approach was implemented to evaluate 2 different dose levels for Cladribine (CLAD)+ LDAC; each 4-week cycle consists of Uproleselan (at fixed dose of 800mg intravenously [IV]). Induction and reinduction if required, included IV uproleselan twice a day from day 1-12; consolidation was given same days but once a day if patients(pts) achieved response (complete response[CR] with incomplete hematological recovery [CRi] or morphologic leukemia-free state [MLFS]). CLAD was IV for 5 days (3.75mg/m2 and 5mg/m2; level -1 and 1 respectively) and subcutaneous LDAC twice daily 10 days (15mg, and 20mg; level -1 and 1 respectively) during induction; consolidation was similar except it was with 3-days of CLAD, for up to 6 cycles, pts aged ≥18 years with a diagnosis of ts-AML with adequate organ function, who have not received therapy for their AML were enrolled. ts-AML is defined as AML arising from previously treated myeloid neoplasm. Presence of the e-selectin was assessed as exploratory analysis. 20 pts have been treated, 18 pts evaluable: 14 (70%) male, median age was 72 yrs (range, 58-86); at the start of therapy, the median bone marrow blasts were 26.5% (20-82%), median WBC was 2.1x10 9/L (0.6-26.4), and median platelets were 26x10 9/L (4-667). Pts had received a median of 1 (1-6) treatments prior to AML transformation. Prior diagnoses were: Chronic Myelomonocytic Leukemia (CMML), MDS, and MDS/MPN in 3 (25%), 14 (70%), and 1 (5%) respectively; all had received HMA, 11 (55%) additionally had received Ven, and 5 (25%) had stem cell transplantation (SCT) prior to enrolling. All pts had unfavorable cytogenetics by ELN 2022. The most frequent mutations were: TET2, TP53, RUNX1 and SRSF2 in 9 (45%), 7 (35%), 6 (30%) and 6 (30%) pts respectively. 18 pts were evaluable for e-selectin; median plasmatic concentration was 26.2ng/mL (15.3-131 ng/mL). Most common AEs were grade(gr) ≥3 neutropenic fever (13 pts, 65%; including 2 gr 5 events), gr 3 bleeding (10%) and gr 2 thrombosis (5%). There were no dose-limiting toxicities observed on dose levels -1 or 1. The chosen dose level was 1 as described above. 2/3 pts who received dose level -1 died during the study follow-up due to sepsis in the first 4-week after induction. Median time to 0.5x10 9/L neutrophil and 50x10 9/L platelets recovery was 30 (17-52) and 38 (20-69) days, respectively. The response rates were 2 (11%) CRi, 1 (6%) CRp, and 4 (22%) MLFS. There was a reduction in BM blasts in 13 pts (72%) (Figure 1). The ORR was 50%(5/10) ( p=0.60) and 20% (1/5) ( p=0.06) among pts who had prior Ven exposure or prior SCT, respectively. The median cycles received was 1.5 (1-4), median cycles at which the best response was achieved was 1 (1-2). 12 pts were taken off protocol due to progression, 3 for death, 3 for allogeneic SCT and 1 continued in remission. The pt who achieved negative MRD-negative by flow cytometry underwent SCT and is still alive. The median follow-up is 8.1 months. Median OS and EFS were 5.3 and 1.4 months respectively; 4-month RFS (CRi, CRp and MLFS) was 30% (Fig 2). In the univariate analysis by Cox regression for plasmatic E-selectin concentration the HR for OS was 1.016 (95% CI 1.002-1.031). Ts-AML, progressing from previously treated antecedent myeloid disorders, is associated with low rates of remission and poor OS. Uproleselan combined with Cladribine + LDAC was well-tolerated with minimal therapy-related AEs - allowing a safe approach to marrow blast reduction and disease control in preparation for a potential allogeneic SCT. We are currently determining the relationship of plasmatic e-selectin concentration and response to treatment.

Trial in Progress: A Phase 1b Single-Arm, Open-Label Study of Emavusertib (CA-4948) in Combination with Azacitidine and Venetoclax in Acute Myeloid Leukemia Patients in Complete Response with Measurable Residual Disease

Background Emavusertib is a novel potent oral inhibitor of interleukin-1 receptor-associated kinase 4 (IRAK4) with additional inhibitory activity against FMS-like tyrosine kinase 3 (FLT3) and CDC-like kinases (CLK1/2/4). Inhibition of these onco-proteins may induce remission thereby addressing a critical unmet need for novel therapies in acute myeloid leukemia (AML). Clinical studies with emavusertib monotherapy have demonstrated a significant reduction in AML blasts with clinical and molecular responses, including patients with relapsed or refractory AML, previously treated with an HMA and/or FLT3 inhibitors (Metzeler 2022). Azacitidine + venetoclax (aza+ven) has been approved in newly diagnosed, unfit patients with AML. In the VIALE-A study, composite complete response (CRc) (CR, CRh, or CRi) in the absence of measurable residual disease (MRD) of <1 residual blast/1000 leukocytes (MRD negative [MRD−]) resulted in longer duration of response (DOR), event-free survival, and overall survival (OS), and better HSCT outcome compared with patients who achieved CRc but were MRD+ (Pratz, 2022). In pre-clinical studies, emavusertib in combination with aza+ven demonstrated synergistic antileukemic effects in AML cell lines, including azacitidine- or venetoclax-resistant cell lines. Adding emavusertib to aza+ven in MRD+ patients at the time of CR may convert MRD status without adding significant toxicity and confirm that emavusertib can be safely added to aza+ven as a potential new regimen in front-line therapy. Study Design: This is a single-arm, open-label Phase 1b trial evaluating safety and tolerability, PK, and conversion of MRD status with emavusertib as an add-on agent to aza+ven in AML patients who achieved CR or CRh with MRD+ based on local testing (EU CT Number 2023-505828-58-00). The primary objective of the study is to determine a safe and tolerable dosing schedule for the triple combination. Secondary objectives include MRD conversion rate, DOR, OS, and pharmacokinetics. The study will enroll approximately 24 patients at 5 to 10 sites globally. Patients will have received azacitidine and venetoclax as first line therapy and achieved CR or CRh after 1-6 cycles of aza/ven. If MRD status remains positive, emavusertib will be added to the existing well tolerated aza+ven regimen. The starting emavusertib dose is 200 mg BID for 7 days per cycle of 28 days. If well tolerated, duration of emavusertib treatment will be extended to 14 and 21, respectively; no intra-patient change of emavusertib dosing duration is planned. The patients will continue triple treatment (emavusertib+aza+ven) until consent withdrawal, disease progression, intolerable toxicity, or not achieving MRD- within 6 cycles of triple treatment. In this Phase 1b trial, MRD can be evaluated by local testing of bone marrow. Key exclusion criteria include residual toxicities and significant comorbidities.

Evidence of antagonism in vitro and in vivo of extracts from Banisteriopsis laevifolia (A. Juss) B. Gates against the rice blast fungus

Rice blast is a common disease caused by Magnaporthe oryzae which affects rice production worldwide, including Brazil. To reduce the use of harmful pesticides, sustainable control options are necessary for managing rice blast. One possible option is to use plant extracts because they produce secondary metabolites capable of inhibiting the pathogen and controlling the disease. This study aimed to evaluate the potential of ethanolic extracts of leaves and flowers from Banisteriopsis laevifollia, a native Brazilian plant, to antagonise M. oryzae. In vitro antifungal activity assays were carried out, in which mycelium growth reduction, conidia germination, and appressorium formation of M. oryzae were evaluated. In addition, in vivo assay for suppression of leaf blast severity by extracts was done. We also explored the identification of secondary metabolites from ethanolic extracts of leaves and flowers by HPLC–HRMS. Results showed that both leaf and flower extracts inhibited mycelial growth in 21.72% and 30.49%, respectively, due to the inhibition of ergosterol production. Additionally, both extracts inhibited melanin production in the mycelium of M. oryzae by inhibiting tyrosine production. Both leaf and flower extracts significantly inhibited conidia germination and appressorium formation. Furthermore, rice leaves treated with the extracts suppressed by 18.17% and 18.97% leaf blast severity, with the 1.00 mg/mL concentration of flower extract and 0.75 mg/mL concentration of leaf extract, respectively, showing the most significant reduction of leaf blast. The extracts contain phenolic compounds, including 2,3,7,8-tetrahydroxy-chromeno-(5,4,3)-chromene-5,10-dione, 3-(4-hydroxyphenyl)-2-propenoic acid, 2-(3,4-dihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol, 3,4′,5,7-tetrahydroxyflavone, 3′,4′,5,7-tetrahydroxyflavone, 4′,5,7-trihydroxyflavanone, 3,3′,4′,5,7-pentahydroxyflavone, 3,3′,4′,5,7-pentahydroxyflavone -3-O-glucoside, and 3,3′,4′,5,7-pentahydroxyflavone-3-O-rutinoside, which are likely responsible for the antifungal activity of the extracts. Overall, this study demonstrates the potential of plant extracts as a sustainable alternative for the management of rice blast.

Venetoclax in Combination with Pediatric-Inspired Chemotherapy in Adults with Newly Diagnosed Acute Lymphoblastic Leukemia: Results of a Phase I Trial

Introduction: Young adults with acute lymphoblastic leukemia (ALL) have favorable outcomes compared with historical standards when treated with an asparaginase-containing pediatric regimen (Stock et al., Blood 2019). We have demonstrated the safety and efficacy of pediatric inspired chemotherapy (PIC) for adults up to age 60 (MSK protocol 12-266, Geyer et al., Haematologica 2021). However, cure rates for adults with ALL remain below 60%, prompting the need for novel agents. Venetoclax (ven) is a BCL2 inhibitor being tested in several clinical trials for ALL. Here, we present the first report of ven used in combination with a multiagent, asparaginase-containing chemotherapy regimen for the upfront treatment of ALL. Methods: We conducted a Phase I, single-center, single-arm clinical trial (NCT05386576) to evaluate the safety and efficacy of ven in combination with PIC in adults with newly diagnosed ALL. Adults aged ≤60 years diagnosed with Philadelphia chromosome negative ALL were eligible for the study. The primary objective was to evaluate the safety of ven in combination with asparaginase-based PIC and identify the maximum tolerated dose and recommended phase II dose. The secondary objectives were to assess the rate of complete remission (CR) and measurable residual disease (MRD) negative CR at day 15 and 28 of Induction I, and end of Induction II. The regimen consisted of 6 treatment phases as previously published (12-266). Ven was administered at a final dose of 400mg (with a rapid dose escalation from 100mg over 3 days) during Induction I (days 5-7 dose escalation, days 7-28 full dose), Induction II (days 1-14 and 29-42), Intensification I & II (days 1-22), and Re-Induction I & II (days 1-14 and 29-42). Measurable residual disease (MRD) was assessed by multiparameter flow cytometry with 10 -4 sensitivity. We used historical data from 22 patients (pts) treated on our previous study, who received the same chemotherapy backbone without ven, as a comparator. Median follow up was calculated using the reverse Kaplan Meier indicator. Duration of treatment was compared using the Wilcoxon rank-sum test. Proportions of pts who achieved MRD-CR were compared with the chi squared test. Results: At the time of analysis, 8 pts had enrolled in the study; all 8 pts completed induction I and 6 (75%) pts had completed induction II (Table 1). Median follow up was 171 days. The median age was 38.5 years (min 25, max 60). 50% of pts had B-cell ALL, and 50% T-cell (including 1 patient with early T-cell progenitor). One patient (12.5%) had CNS disease (CNS 3) at diagnosis. Four (50%) pts had intermediate risk cytogenetics by CALGB 19802 classification (Stock et al., Cancer 2013), 2 (25%) had unfavorable, and 1 (12.5%) favorable. Two (40% of B-ALL) had a Philadelphia-like phenotype. During Induction I & II, 4 (50%) pts experienced febrile neutropenia, 6 (75%) grade 4 thrombocytopenia, and all 8 (100%) grade 4 neutropenia. No dose limiting toxicities, as defined per protocol, were observed. The average duration of Induction I on study was 46.6 days compared to 43.6 on 12-266 (p = 0.11). The average duration of Induction II on study for pts who had completed it at the time of analysis was 102 days compared to 74 days on 12-266 (p = 0.02), primarily due to cytopenias. Three (37.5%) of pts achieved an MRD negative CR by the end of Induction I. Of the 6 pts who had completed Induction II by time of analysis, 5 (83%) had achieved an MRD- CR, compared to 81% on 12-266 (p = 0.90) and 1 patient had refractory extramedullary disease. We assessed kinetics and depth of response by plotting the average blast percentage in the bone marrow by flow cytometry across three different timepoints. Pts on the study had numerically lower blast percentages at day 15, end of Induction I and end of Induction II compared to 12-266 (Figure 1). At the time of this analysis, no patient who entered CR had experienced disease relapse. Conclusions: Ven addition to a PIC backbone was overall safe with high MRD negative remission rates in this preliminary report. Compared to historical controls, pts treated with ven had a longer duration of Induction II primarily due to cytopenias, and we are amending the study to shorten ven duration during induction II. Pts treated with ven had a numerically faster reduction in bone marrow blasts compared to historical controls. Longer follow up in a larger patient population in this ongoing study will be required to assess long term toxicity and efficacy of this regimen.

Preliminary Safety and Efficacy of Emavusertib (CA-4948) in Acute Myeloid Leukemia Patients with FLT3 Mutation

Background Acute myeloid leukemia (AML) is a heterogenous disease and exhibits a dynamic mutational landscape as the disease progresses. Internal tandem duplication (ITD) of FLT3 is considered an acquired late-event mutation and is associated with a poor prognosis in AML. Emavusertib is a potent oral inhibitor of IRAK4 and FLT3, conferring potential efficacy advantages compared to other IRAK4 and FLT3 inhibitors. IRAK4 is upregulated during anti-FLT3- or other cytotoxic therapies, which could drive a resistance pathway of early relapse and progression (Melgar 2019; Li 2019). Presence of spliceosome mutations U2AF1 or SF3B1 results in excessive IRAK4-L and further enhance toll-like receptor pathway activation (Smith 2019). Methods The safety, clinical activity, and potential biomarkers of emavusertib in relapsed/refractory (R/R) AML and higher-risk myelodysplastic syndrome are being investigated in the ongoing open-label, Phase 1/2a TakeAim Leukemia trial (NCT04278768). Here we present preliminary safety and efficacy data in the subset of enrolled AML patients who carried FLT3 mutation (FLT3m) at baseline and were treated with emavusertib monotherapy. Patients' mutational profiles were documented based on local testing results. Results As of 12 June 2023, 10 R/R AML patients with FLT3m have been treated at initial doses of 200, 300, or 400 mg BID. There was 1 patient with FLT3-TKD and 9 patients with FLT3-ITD, of which 2 carry both FLT3-ITD and U2AF1 mutations, and 1 with both FLT3-TKD and SF3B1 mutations. The median number of prior anti-cancer therapies was 3 (range 1-6) and 7 out of 10 patients had prior exposure to gilteritinib. Two patients with prior gilteritinib exposure also received midostaurin therapy. Treatment-emergent adverse events (TEAEs) Grade ≥ 3 were reported in 7/10 (70%) patients, and the majority of Grade ≥ 3 TEAEs were reversible and manageable. No dose-limiting toxicity was reported in these 10 patients. Five of 9 response evaluable patients demonstrated more than 90% bone marrow blast reduction compared to baseline. Enrollment is being expanded in this trial at the Recommended Phase 2 Dose (RP2D) of 300 mg BID for patients with ≤ 2 prior lines of therapy. Preliminary data for the 3 response evaluable patients in this population (for whom baseline and post-treatment marrow assessments were available) include blast count reductions of 99%, 100%, and 100% and include 2 CRs and 1 morphologic leukemia-free state (MLFS), with on-treatment duration of 213 days, 225 days, and 134 days, respectively. FLT3-ITD became undetectable in both patients achieving CR. Conclusion Emavusertib has a favorable safety profile in heavily pretreated AML patients with FLT3m and demonstrated anti-cancer activity in patients with FLT3m, including patients who have progressed on prior FLT3 inhibitor. No dose-limiting myelosuppression was reported. In addition, mutational profiles are suggestive of disease-modifying activity of emavusertib. Enrollment in this trial is continuing at a dose of 300mg BID (phase 2 expansion cohort) for patients with ≤ 2 prior lines of therapy.

Non-isothermal kinetics of coke and iron ore melting reduction with variable activation energy model

Due to the significant consumption of coke in blast furnace ironmaking, a large amount of carbon emissions is generated. Thus, addressing the issues of energy conservation and carbon emission reduction in blast furnace ironmaking is imperative. The melting reduction reaction constitutes the predominant portion of carbon consumption during the ironmaking process. However, its kinetic behavior remains unclear to date, impeding energy-saving and carbon reduction efforts in blast furnaces. Consequently, this study conducted melting reduction experiments on two types of sinters and coke under simulated blast furnace conditions. A variable activation energy model (VAEM) was established for kinetic analysis of melting reduction. The conclusion is as follows: the variable activation energies of two types of sinters were determined to vary between 110 and 50 kJ/mol and 115–60 kJ/mol, the pre-exponential factors were 1.36 and 2.57. The deviation analysis showed that the predicted values using VAEM deviated from the experimental values by 1.17 % and 0.95 %. The reliability of VAEM was demonstrated. In turn, the kinetic behavior of coke and iron ore melting reduction was declared. It offers a theoretical basis for promoting the rational use of coke resources in blast furnace ironmaking and reducing carbon emissions.

Spliceosome mutations are associated with clinical response in a phase 1b/2 study of the PLK1 inhibitor onvansertib in combination with decitabine in relapsed or refractory acute myeloid leukemia

PLK1 is overexpressed in acute myeloid leukemia (AML). A phase 1b trial of the PLK1 inhibitor onvansertib (ONV) combined with decitabine (DAC) demonstrated initial safety and efficacy in patients with relapsed/refractory (R/R) AML. The current study aimed to identify molecular predictors of response to ONV + DAC in R/R AML patients. A total of 44 R/R AML patients were treated with ONV + DAC and considered evaluable for efficacy. Bone marrow (BM) samples were collected at baseline for genomic and transcriptomic analysis (n = 32). A 10-gene expression signature, predictive of response to ONV + DAC, was derived from the leading-edge genes of gene set enrichment analyses (GSEA). The gene signature was evaluated in independent datasets and used to identify associated mutated genes. Twenty percent of the patients achieved complete remission, with or without hematologic count recovery (CR/CRi), and 32% exhibited a ≥50% reduction in bone marrow blasts. Patients who responded to treatment had elevated mitochondrial function and OXPHOS. The gene signature was not associated with response to DAC alone in an independent dataset. By applying the signature to the BeatAML cohort (n = 399), we identified a positive association between predicted ONV + DAC response and mutations in splicing factors (SF). In the phase 1b/2 trial, patients with SF mutations (SRSF2, SF3B1) had a higher CR/CRi rate (50%) compared to those without SF mutations (9%). PLK1 inhibition with ONV in combination with DAC could be a potential therapy in R/R AML patients, particularly those with high OXPHOS gene expression and SF mutations.

Developmental patterns and individual differences in responding to social feedback: A longitudinal fMRI study from childhood to adolescence

Learning to control behavior when receiving feedback underlies social adaptation in childhood and adolescence, and is potentially strengthened by environmental support factors, such as parents. This study examined the neural development of responding to social feedback from childhood to adolescence, and effects of parental sensitivity on this development. We studied these questions in a 3-wave longitudinal fMRI sample (ages 7–13 years, n = 512). We measured responses to feedback using the fMRI Social Network Aggression Task through noise blasts following peer feedback and associated neural activity, and parental sensitivity using observations of parent-child interactions during Etch-a-Sketch. Results revealed largest reductions in noise blasts following positive feedback between middle and late childhood and following negative feedback between late childhood and early adolescence. Additionally, brain-behavior associations between dorsolateral prefrontal cortex activation and noise blast durations became more differentiated across development. Parental sensitivity was only associated with noise blast duration following positive feedback in childhood, but not in adolescence. There was no relation between parental sensitivity and neural activity. Our findings contribute to our understanding of neural development and individual differences in responding to social feedback, and the role of parenting in supporting children’s adaption to social feedback.

Blast and Bacterial Diseases of Some Seed-dressed Rice Varieties in Yogyakarta.

Pyricularia grisea (blast disease) and bacterial diseases resulted rice yield loss. Tolerant varieties and seed-dressing are expected reduces the disease. This research was aimed to define the effect of tolerant varieties and seed - dressing to the incidence of blast and bacterial diseases. Research was conducted at endemic area in Yogyakarta Indonesia from November 2021 to March 2022. The experiment was designed in randomized block with 2 factors and 4 replications. Factor 1 was variety: Inpari 32 HDB, Inpari 45 Dirgahayu and Inpari 48 Blas as tolerant variety and Sunggal as common variety. Factor 2 was seed treatment: Pseudomonas fluorencens solutions, consortia of antagonist fungi and bacterium, and fungicide Trisiklazol 225 g l−1 and Azoksistrobin 75 g l−1. Results showed that tolerant varieties was significantly reduced blast and BLB. The highest incidence of blast and bacterial diseases were found at Sunggal, while not found at Inpari 45 Dirgahayu and Inpari 48 Blas. Meanwhile, bacterial diseases was found at low level at the 3 tolerant varieties. Bacterial disease found in this research was BLB (Bacterial Leaf Blight), BRS (Bacterial Red Stripe) and BLS (Bacterial Leaf Streak). Result also showed that seed treatment did not affect the reduction of blast and bacterial disease. At other site, highest yield (10.18 ton ha−1) was obtained from Inpari 32 HDB which was treated with consortia of antagonist fungi and bacterium. Hence, the 3 tested tolerant varieties was promising to be established at the endemic area in the agro ecosystem of irrigated rice in Yogyakarta Indonesia.

Palbociclib in Acute Leukemias With KMT2A-rearrangement: Results of AMLSG 23-14 Trial.

Palbociclib in Acute Leukemias With KMT2A-rearrangement: Results of AMLSG 23-14 Trial.

Abstract CT101: Phase I study of the T-cell receptor-like antibody Hu8F4 in patients with advanced hematologic malignancies

Abstract Background: Despite recent advances in the treatment of AML, most approaches are rarely curative and most patients (pts) succumb to relapsed disease. The effectiveness of stem cell transplant and associated graft vs. leukemia effect implies an important role for immune-based therapy in producing long lasting remissions. Traditional approaches using immunotherapy have failed to establish a suitable surface target or treatment paradigm that is effective in myeloid malignancies. Hu8F4 is a humanized T-cell receptor-like monoclonal antibody that binds to the conformational epitope of PR1 bound to HLA-A2, which is highly, differentially expressed on the surface of AML compared to normal progenitors. Methods: We conducted a first in human, phase I dose escalation trial of Hu8F4 in pts with myeloid malignances. Pts with R/R AML, MDS, CMML, and myeloid blast phase of CML with adequate organ function and PS ≤ 2 were eligible. Pts were treated on 7 escalating dose levels, ranging from 0.01 mg/kg to 10 mg/kg IV on D1 & 15. Initial dose levels required 1 pt per dose (0.01, 0.03, 0.1, 0.3, 1), followed by 3 pts per dose (3, 10). Results: 10 pts with R/R AML have been enrolled, with a median age of 65 years (range, 23-77), including 6 females (60%). Pts had received a median of 4 (1-4) prior therapies; 5 pts (50%) had a PS of 2. At enrollment, the median WBC was 1.9 (0.1 - 18.4), median BM blasts were 32% (8 - 76); 9 (90%) pts had complex karyotype and 3 (30%) had a TP53 mutation. All pts had > 98% surface expression of PR1 on the myeloid blasts. Hu8F4 Cmax ranged up to 160,000 ng/mL with t1/2 of 48 hours and clearance of 2.61 hr*ng/mL at the highest dose. Weak anti-drug antibodies were observed after week 4 in 2 of 3 pts treated at 3 mg/kg. With a median follow up of 3.5 months (1.1 - 9.9), pts have received a median of 1 (1-4) cycle of therapy. Two pts had decline in BM blasts and 4 had stable disease. Routine peripheral blood testing revealed sharp decline in peripheral blasts immediately after infusion of Hu8F4 on D1 and 15 with associated elevation in serum LDH in some pts and a rise in normal granulocytes, consistent with on-tumor effects. The pharmacokinetic parameters and transient blast reduction indicated a possible sink effect mediated by high levels of circulating blasts. SAEs documented on study were mostly disease-related and included infections, cytopenias, hemoptysis, pneumonia, and GI bleeding. Treatment related AEs were temporally related to the infusion included hypotension (Grade 2: N=2), rigors (Grade 2: N=2; Grade 1: N=1). All infusion reactions were observed at dose levels of 3 and 10 mg/kg, but were transient, and managed with steroids and antihistamines. All pts proceeded with their next dose without further issues. No cytokine release syndrome or neurologic toxicity was observed. Correlative studies support antibody dependent cellular cytotoxicity and phagocytosis as important mechanisms of anit-AML activity. Conclusion: Hu8F4 was well tolerated with no dose-limiting toxicities observed at the maximum planned dose. On-target peripheral blast reduction temporally related to infusion suggests biological activity. Real-time pharmacokinetic data on study indicate a possible sink effect that may be overcome by a more frequent dosing strategy. Citation Format: Tapan M. Kadia, Hagop Kantarjian, Gheath Alatrash, Anna Sergeeva, Hong He, Lisa St. John, Priya Koppikar, Celine Kerros, Abhishek Maiti, Courtney Dinardo, Elias Jabbour, Serge Vesrstovsek, Naveen Pemmaraju, Nitin Jain, Ghayas Issa, Guillermo Montalban-Bravo, Aditi Shastri, Daniel Couriel, Rhona Pinsoy, Sapna Parshottam, Richard Champlin, Jorge Cortes, Jeffrey Molldrem. Phase I study of the T-cell receptor-like antibody Hu8F4 in patients with advanced hematologic malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT101.

Abstract 6150: AZD0466, a dual BCL-2/XL targeting nanomedicine, is active in small cell lung cancer models

Abstract Small cell lung cancer (SCLC) is an aggressive malignancy with critical need for new therapies. While currently treated as a single disease, SCLC is heterogenous, comprised of several transcriptional subtypes. Each of these subtypes has distinct drivers and may warrant unique therapeutic targets. Two potential therapeutic targets for SCLC are the pro-survival proteins BCL-2 and BCL-XL. BCL-2 is overexpressed in ASCL1 (A) and POUF3 (P) subtypes of SCLC. We therefore sought to evaluate efficacy of the dual BCL-2/XL inhibitor AZD0466 in SCLC models and to determine whether transcriptional subtype would predict response. AZD0466 is a novel drug-dendrimer conjugate. The active moiety, AZD4320, is a potent dual inhibitor of BCL-2 and BCL-XL. AZD4320 is covalently conjugated to a 5th-generation PEGylated poly-lysine dendrimer through a hydrolytically labile linker to make AZD0466. AZD0466 has been optimized to deliver efficacy while mitigating potential Cmax-driven on-target toxicities of AZD4320. AZD4320 was active (IC50 ≤0.1 µM) in 9/27 SCLC cell lines. AZD4320 in vitro sensitivity was enriched in cell lines that represented A and P subtypes of SCLC compared to NEUROD1 and YAP1 subtypes. We next profiled AZD0466 in a panel of SCLC patient-derived models: 14 patient-derived xenografts and 10 circulating tumor cell-derived xenografts. AZD0466 monotherapy dosed weekly IV was active in 12/24 SCLC xenografts, driving regressions in 8 models. AZD0466 drove efficacy and cleaved caspase-3 induction in a dose-dependent manner. Similar to in vitro, AZD0466 in vivo efficacy was enriched in subtype-A, driving responses in 10/14 ASCL1 models (7 regression, 3 stable disease). AZD0466 response also correlated strongly with BCL-2 mRNA expression (P<0.0001). AZD0466 outperformed the selective BCL-2 inhibitor venetoclax in 6/10 models. Notably, AZD0466 was active in models resistant to platinum/etoposide chemotherapy, the standard-of-care for SCLC. Together, these data suggest BCL-2/XL inhibition has therapeutic potential in SCLC. AZD0466 is in clinical development. The first-in-human study treated 9 patients with advanced solid tumors (NCT04214093) at doses from 50-200mg, all of which were well-tolerated. The BOR was SD observed in 3 patients (100mg) with 1 patient receiving treatment for 5.5 months. AZD0466 is now under evaluation in patients with hematologic malignancies (NCT04865419 and NCT05205161). AZD0466 has been dosed in 33 patients up to 2400mg. No DLTs have been reported to date. Initial clinical activity has been observed through reduction of bone marrow blasts following AZD0466 treatment. AZD0466 exhibits linear PK, consistent across solid tumor and leukemia patients. The doses tested are in line with preclinical studies in SCLC. Citation Format: Courtney L. Andersen, Giulia Fabbri, David Jenkins, Zumla Cader, Shringi Sharma, Areya Tabatabai, Srividya Balachander, Jordan Roebuck, Melanie Galvin, Kathryn Simpson, Caroline Dive, Jordi Rodon Ahnert, Jamal Saeh. AZD0466, a dual BCL-2/XL targeting nanomedicine, is active in small cell lung cancer models. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6150.

Phase 1 Results of the First-in-Class CXCR1/2 Inhibitor SX-682 in Patients with Hypomethylating Agent Failure Myelodysplastic Syndromes

Background: SX-682 is an oral dual allosteric inhibitor of the CXCR1 and CXCR2 (CXCR1/2) chemokine receptors, a signaling pathway involved in the recruitment of immunosuppressive MDSCs and autocrine growth of disease-initiating leukemic stem cells (LSCs) in AML and myelodysplastic syndromes (MDS). CXCR2 overexpression is predictive of transfusion dependence in MDS. CXCR2 inhibition reduces proliferation of leukemic cell lines and primary MDS/AML patient (pt) samples in vitro and impairs leukemic growth in an in vivo AML animal model. CXCR2 is also involved in normal neutrophil egress from the bone marrow and thus absolute neutrophil count (ANC) serves as a pharmacodynamic (PD) marker for CXCR1/2 inhibition by SX-682. In pts with normal bone marrow, 25-400 mg SX-682 twice-daily (BID) dose-dependently reduces ANC, with maximum ANC reduction (-66% of baseline) obtained at >150 mg BID, consistent with maximum CXCR1/2 inhibition above this dose. ANC rapidly (24 hrs) normalizes with dose-holding. This NHLBI funded trial (HL142389, NCT04245397) explored the safety and efficacy of SX-682 monotherapy in pts with hypomethylating agent (HMA) failure MDS. Methods: This Phase 1 dose-escalation with expansion study treated five cohorts of HMA failure MDS pts with escalating 25-400 mg BID doses of SX-682 in six continuous 28-day cycles with responding pts continuing treatment. Steady-state pharmacokinetics (PK) were obtained. Response assessment was at the end of cycles 1, 3 and 6 and every third cycle thereafter using IWG criteria (Cheson 2006). This interim analysis after dose-escalation to select the expansion dose was pre-specified. Results:17 MDS pts received SX-682 (median 1 prior therapies; range 1-4) with 6 pts in the 200 mg cohort, 3 pts in each of the 25, 50 and 100 cohorts and 2 pts in the 400 mg cohort (Table). Median age was 76, and pts were low (n=1), intermediate-1 (n=10), intermediate-2 (n=5) and high (n=1) risk by the International Prognostic Scoring System (IPSS). All pts were transfusion-dependent and all had failed prior HMA and 24% lenalidomide. Steady-state PK exhibits increasing drug plasma concentration with dose comparable to pts with solid tumors. The ANC PD marker exhibited a dose-dependent decrease from baseline (ΔANC) that plateaued in the 200 and 400 mg dose cohorts consistent with maximum receptor inhibition (Table). Marrow MDSCs and LSCs were reduced after initiation of SX-682. SX-682 was well-tolerated with no maximally tolerated dose and no pt discontinued treatment for adverse events. Treatment-emergent adverse events > grade 3 were most common in the 200 and 400 mg dose cohorts, and those related to neutrophils are consistent with being related to SX-682. Effects on neutrophils reversed on cessation of drug dosing. There was a dose-dependent increase in overall response rate (ORR) from 0% at 25 mg BID to 50% at 200 mg BID consistent with the observed clinical benefit being related to CXCR1/2 inhibition by SX-682 (Table). Four of the five responders had mutant genes (MGs) involving splicing factors (60% of responders; SF3B1, SRSF2) and/or epigenetic regulation (60% of responders; TET2, ASXL1, IDH2). Across all dose cohorts, 8 of 17 (47%) pts had a reduction in marrow blasts after initiating SX-682 (Figure). The 200 mg dose yielded the most rapid and deep reduction in blasts with 2 of 6 pts (33%) achieving a marrow complete remission (mCR) in keeping with this dose providing maximum receptor inhibition. There was hematologic improvement (HI) in 3 pts with one having a durable near-CR response (on SX-682 >500 days) consisting of trilineage HI (hemoglobin > 10 g/dL) and transfusion independence for over 4 months (pt required 16 transfusions in the 7 weeks before starting SX-682 therapy). Based on ANC PD, ORR and marrow blast responses, the 200 mg BID dose was selected for the expansion phase of the trial. Conclusions: SX-682 is a novel therapy in HMA failure MDS with dual activity against LSCs and MDSCs. SX-682 was well tolerated with encouraging efficacy with a biologically effective oral dose selected at 200 mg BID. An expansion cohort in both lower and higher risk MDS pts is ongoing and will additionally include HMA naïve patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pediatric Acute Myeloid Leukemia with Co-Occurring BCR::ABL and CBFA2T3::GLIS2 Dual Fusion with Deep Response to FOLR1-Targeting Antibody Drug Conjugate Stro-002 and Tyrosine Kinase Inhibitor

Introduction: Pediatric acute myeloid leukemia (AML) is characterized by significant cytogenetic and molecular heterogeneity. AML with CBFA2T3::GLIS2 fusion (CBF::GLIS) involving infants and very young children is a rare but uniformly refractory disease with high mortality. Laboratory data demonstrates that this fusion is sufficient for leukemic transformation without recurrent secondary variants. These studies have also linked CBF::GLIS fusion to induction of folate receptor alpha (FOLR1) expression in transformed cells (Meshinchi et al, 2020). Incidence of Ph+ de novo (BCR::ABL minor breakpoint, p190 hybrid) disease ranges from 0.5-3% of all AML cases across the age spectrum (Soupir et al, 2017). We, for the first-time, report dual existence of both fusions in a child with AML and discuss novel interventions including combination of a BCR::ABL tyrosine kinase inhibitor (TKI) and antifolate therapy consisting of methotrexate (MTX) and FLOR1-specific antibody-drug conjugate (ADC) STRO-002 (Sutro Biopharma) based on available data regarding its in-vitro preclinical activity in CBF::GLIS disease (Meshinchi et al, ASH abstract, 2021). Case: A 2-year-old girl of Vietnamese descent received a bone marrow examination for bicytopenia and macrocytosis. Flow cytometry confirmed the poor prognostic RAM immunophenotype AML (CD45 dim, HLA-DR negative, CD38 dim, CD56 bright) and FOLR1 expression. Marrow aspirate smears showed numerous hypercellular spicules and blasts with scant cytoplasm and some blebbing but no granules or Auer rods. Marrow exhibited 100% cellularity. CNS was not involved. Review of diagnostic genomic profile mid induction showed a BCR::ABL minor breakpoint fusion as well as CBF::GLIS fusion. The child began AML induction on COG AAML1831 trial randomized to the experimental arm with CPX-351 and gemtuzumab ozogamicin (GO). Due to lack of response to AML therapy at end of Induction (EOI) I, she was taken off protocol and started on modified ALL regimen for Induction II consisting of cytarabine, low dose weekly methotrexate and bimonthly peg-asparaginase with addition of an oral TKI, dasatinib. EOI II marrow examination showed improvement with reduction in blasts (11%) and detectable BCR::ABL but undetectable CBF::GLIS by Q-RT-PCR. Induction III included low dose weekly methotrexate, cytarabine, GO, and dasatinib. EOI III marrow examination showed complete morphologic remission (CR) with no evidence of minimal residual disease (MRD) or fusion transcripts of either clone. Due to availability of a matched sibling donor, the child underwent hematopoietic stem cell transplantation (HSCT); however, was noted to have 3% blasts on day +83 marrow examination despite previously commencing dasatinib post-transplant prophylaxis. BCR::ABL and CBF::GLIS transcripts were again detectable at low levels. Dasatinib dosage was maximized and weekly MTX and bimonthly peg-asparaginase were reintroduced, but the marrow disease burden increased significantly to 78% blasts positive only for CBF::GLIS fusion. Given availability of FOLR1 directed ADC on single-patient compassionate use basis, patient received single agent STRO-001 on a bi-monthly basis. With rising ANC, evaluation of marrow after 2nd STRO-002 dose remarkably showed CR with MRD negative remission by flow and molecular studies. This time remission was consolidated with monthly STRO-002 and donor lymphocyte infusions (DLI). Currently, patient remains in MRD-negative remission after the 3 of 4 planned STRO-002/DLI maintenance. Patient has maintained a 100% Lansky play score and tolerated the regimen with only prolonged initial cytopenia requiring supportive care as a toxicity. Plan is to continue TKI and monthly STRO-002 as maintenance therapy. Conclusion: Complete genomic sequencing has revolutionized pediatric AML categorization. It is quite conceivable that (BCR::ABL, CBF::GLIS) dual fusion disease will become a more common finding in future. Although CBF::GLIS AML is uniformly refractory to conventional therapy, targeted therapy with FOLR1-directed STRO-002 was highly effective in eliminating CBF::GLIS clone in this patient, and combination with DLI appears to be feasible. Long-term follow-up is required to assess durability of remission. Additional testing of this approach in a larger patient population is needed to determine the role of STRO-002 in this high-risk pediatric AML population. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Multiomics Analysis Confirms Effective Target Engagement for RVU120 - a First-in-Class CDK8/19 Kinase Inhibitor in AML and MR-MDS Patients and Reveals the Mechanism of Action

RVU120 is a first-in-class CDK8/19 kinase inhibitor. The primary objective of an ongoing Phase Ib study of RVU120 in AML and HR-MDS patients is to determine the preliminary safety profile and the recommended phase 2 dose of RVU120 as a single agent. Characterization of pharmacodynamic (PD) effects is a secondary objective of the trial. PD analysis supports the determination of the recommended phase 2 dose, further clinical development and ultimately positioning of this novel class of targeted agents in the treatment strategies for AML and MDS patients. A battery of tests has been used to establish the relationship between pharmacokinetics (PK) and PD activity, confirm the on-target activity of RVU120, and reveal a mechanism of action of CDK8/19 inhibitors in preclinical models. Specific protein binding of RVU120 in leukemic and normal blood cells has been verified by capturing CDK8/19 kinases after a competition with ATP acyl-phosphate biotin-labeled probes. Changes in CDK8- dependent phosphorylation of STAT5 were used as proximal biomarkers and were measured by flow cytometry. Transcriptome changes were used as downstream biomarkers and were determined by the integrated analysis of bulk RNAseq, ChIPseq and ATACseq. The molecular activity of RVU120 was correlated with anti-leukemic activity and surface marker changes. In patients, PD activity of RVU120 was established by measuring changes in pSTAT5 levels, directly in blast cells and ex vivo in established AML cell lines, exposed to plasma collected from patients treated with RVU120. Downstream transcriptomic effects in patients were assessed by RNAseq and phenotypic changes were tracked by flow cytometry surface marker panels. Preclinical profiling indicated effective CDK8/19 target engagement and inhibition of pSTAT5 levels at low nanomolar concentrations of RVU120, in both established cell lines and primary leukemic cells. The antileukemic activity was tightly correlated with levels of biomarker inhibition, however, in a group of super-responders enriched for NPM1 mutants and leukemic stem cells, efficacy was achieved at partial biomarker inhibition levels. Downstream profiling revealed inhibition of homeobox genes and induction of STAT5-dependent genes as two major transcriptomic programs regulated by RVU120. Homeobox genes inhibited by RVU120 are essential for the viability and self-renewal of leukemic cells, whereas many STAT5 -dependent genes are known as master regulators of erythropoiesis. Consistently, treatment of healthy and transformed CD34+ cells with RVU120 results in the commitment to erythropoiesis. Profiling of patient samples largely confirmed preclinical findings. Inhibition of pSTAT5 in CD34+ blasts from AML and MDS patients tightly correlated with achieved exposures after the first dose and at a steady state. At the time of submission pSTAT5 inhibition has already reached >50%, a threshold that based on preclinical predictions is sufficient for robust efficacy in selected groups of super-responder patients. Further increase at higher doses, is expected to result in deeper, more durable responses in broader populations of patients. Broad transcriptomic changes were observed in patients after treatment with RVU120. Notably, potent inhibition of homeobox genes was observed in NPM1 mutant blasts and induction of erythroid master regulator genes was observed in SF3B1 mutant cells with erythroid arrest. Clear hallmarks of erythroid differentiation were further identified in several patients by specific changes in surface markers. These patients achieved meaningful clinical responses such as reduction of blasts and transfusion independence, respectively.

Molecular Characterization of Clinical Response in Relapsed/Refractory Acute Myeloid Leukemia and High-Risk Myelodysplastic Syndrome Patients Treated with Single Agent Emavusertib

Introduction Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) are myeloid malignancies that exhibit a dynamic mutational landscape as the disease progresses. Genetic mutations in the splicing factors SF3B1 and U2AF1 drive overexpression of a highly active long isoform of interleukin-1 receptor-associated kinase 4 (IRAK4), which is critical in triggering inflammation, oncogenesis, and survival of cancer cells. Splicing factor mutations are frequently reported in AML and MDS and have been associated with disease progression and poor prognosis in relapsed/refractory (R/R) diseases. Emavusertib is a potent oral inhibitor of IRAK4 as well as Fms-like tyrosine kinase 3 (FLT3). The safety, clinical activity, and potential biomarkers of emavusertib in AML or high-risk MDS (HR-MDS) are investigated in the ongoing open-label, phase 1/2a TakeAim Leukemia trial (NCT04278768). Methods Eligible patients with R/R AML or HR-MDS were enrolled and treated with emavusertib. The exploratory objectives of the study are to assess the association between clinical activity and target-related biomarkers, gene expression signatures, and molecular subtypes. Bone marrow or peripheral blood were collected at the baseline and on treatment. To characterize the mutational profiles of enrolled patients and further define the targeted population, targeted next generation sequencing (NGS) of 68 genes was performed on genomic DNA from bone marrow or peripheral blood mononuclear cells. A minimum coverage of 100x, variant allele frequency (VAF) of >1%, and a VARSCAN-assigned variant p<0.001 were used as thresholds for single nucleotide variants (SNV) calling and presumed somatic driver mutations were identified as previously reported (Metzeler et al. Blood 2016). Mutations from patients’ molecular pathology reports were also documented. Results As of December 16, 2021, 49 patients have been treated with emavusertib monotherapy at one of dose levels of 200, 300, 400, or 500 mg BID, including 30 R/R AML and 19 R/R HR-MDS. The median number of prior anti-cancer therapies was 2 (range 1-5). This abstract is intended to add additional molecular findings to the patient subset presented in 2022 ASCO, of which 6 AML and 7 HR-MDS had splicing factor SF3B1 or U2AF1 mutations and 3 AML had FLT3 mutations, including 2 AML with both splicing factor and FLT3 mutations (hereafter referred to as "targeted mutations"). In the patients with targeted mutations, with available mutational profile data or molecular reports from sites, there were 6 responders: 1 CR, 1 CRh, and 4 mCR. In this responder population, the most common co-mutation was ASXL1. During emavusertib treatment, FLT3-mutated clones became undetectable in 2 of 3 (67%) FLT3-mutated AML patients. One of the 3 patients (33%) with a FLT3 mutation achieved CR and the remaining 2 patients achieved SD (1 with > 90% blast reduction). Additional gene mutations, such as ASXL1, RUNX1, CEBPA, ETNK1, ETV6, and SRSF2, became undetectable during emavusertib treatment. New mutations that emerged after ≥ 1 cycle of emavusertib treatment include NRAS, SETBP1, RUNX1, WT1, STAG2, KRAS, CCND2, DNMT3A, ASXL1, and NOTCH1. Analysis of genomic and transcriptomic profiles will be updated. Conclusion Emavusertib demonstrated anti-cancer activity in heavily pretreated AML and HR-MDS patients, especially in those with U2AF1, SF3B1, or FLT3 mutations. Our preliminary NGS data is suggestive of molecular responses and disease-modifying activity of emavusertib. Patients with targeted mutations responded to emavusertib, even in the presence of co-mutations of ASXL1 that are typically associated with poor prognosis. We will continue to explore potential genomic biomarkers of emavusertib sensitivity and resistance

First in Human Clinical Responses and Persistence Data on TEG001: A Next Generation of Engineered Αβ T Cells Targeting AML and MM with a High Affinity γ9δ2TCR

Introduction: γδT cells target malignant cells by sensing cancer mediated metabolic changes via their γδTCR[1]. We have developed the TEG001 cell product as an 'academic in house product', which are αβ T cells expressing the high affinity Vγ9Vδ2 TCR clone 5 [2]. TEG001 showed tumor reactivity towards a range of malignant cell lines, primary material from patients with various hematological malignancies as well as efficacy in murine models[3]. Here we present the results of dose level 1 and 2, addressing the safety and tolerability of TEG001 in patients with acute myeloid leukemia (AML) or multiple myeloma (MM) (NL6357). Methods: The TEG001 study (NL6357), is a single center, investigator-initiated study, with a standard 3+3 dose escalation design. Cohorts receive a single infusion of 1x106 TEG001 cells/kg (dose level 1), 3x106 TEG001 cells/kg (dose level 2) and 1x107 TEG001 cells/kg (dose level 3). Relapsed and/or refractory AML/high risk MDS and MM patients were eligible. AML patients with > 30% blasts or circulating blasts required bridging therapy. TEG001 cells were produced as previously described[2]. The conditioning regimen consisted of fludarabine i.v. 25 mg/m2 (day -4 to -2) and cyclophosphamide i.v. 900 mg/m2 (day -2). Pamidronate (PAM) (30 mg I.V.) was administered on day 0 and on day 28 to propagate TEG001 activity. TEG001 is detected in peripheral blood samples by flow cytometry as part of immune monitoring (details in Fig. 2). The primary endpoint was the development of dose-limiting toxicities (DLTs) in order to determine the maximum tolerated dose. Main criteria for reaching DLTs were TEG001 related adverse events (AEs) requiring ventilator support and grade 4 AEs not related to the underlying disease. AEs contributable to cytokine release syndrome (CRS) and/or immune effector cell-associated neurotoxicity syndrome (iCANS) grade 3 responding to tocilizumab and/or steroids were not defined as a DLT. Results: Fourteen patients were included. Of the six patients that were not infused, three patients did not respond to bridging chemotherapy, for two patients TEG001 product could not be manufactured for the intended target dose level and one patients went off study due to COVID-19 induced hospital restrictions. Eight patients were dosed: three patients in dose level 1 and three patients in dose level 2. Two patients received an 'out of specification' dose (77% of dose level 1; and 36% of dose level 2, respectively). Of the six patients infused in dose level 1 and 2, five patients had AML and one patient had MM (Fig. 1). No DLTs were observed. No AEs > grade 3 related to TEG001 were observed. Patient 16 (dose level 2), who received PAM according to the protocol on day 0 and 28, developed 2 seizures at day 29 and 30. The seizure responded well to levetiracetam and no other neurological signs associated with iCANS were observed. No infections or abnormalities in the spinal fluid or brain imaging were identified and connection of the seizure to TEG001 remained inconclusive. In all patients TEG001 cells were detectable in peripheral blood by flowcytometry (dose level 2 depicted in Fig. 2). In dose level 1, patient 7 had stable disease (SD, duration 3M). In dose level 2, patient 9 had a blast reduction (not meeting criteria for partial remission (PR); duration 12M) and patient 16, who had 28% bone marrow blasts prior to TEG001 infusion showed full hematological recovery (Fig. 2) and achieved a complete remission (CR, duration 6M). Conclusion: TEG001 cells are well-tolerated at the first 2 dose levels tested. TEG001 cells show persistence up to day 56. One out of three AML patients in dose level 2 achieved a CR one month after TEG001 infusion and SD was observed in both dose levels. The TEG001 study is currently recruiting patients for dose level 3 (1x107 cells/kg). This study was financially supported by Gadeta b.v. [1] Sebestyen, Z., et al., Translating gammadelta (gammadelta) T cells and their receptors into cancer cell therapies. Nat Rev Drug Discov, 2019. [2] Straetemans, T., et al., GMP-Grade Manufacturing of T Cells Engineered to Express a Defined gammadeltaTCR. Front Immunol, 2018. 9: p. 1062 [3] Johanna, I., et al., Evaluating in vivo efficacy - toxicity profile of TEG001 in humanized mice xenografts against primary human AML disease and healthy hematopoietic cells. J Immunother Cancer, 2019. 7(1): p. 69. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal