Untreated Acute Myeloid Leukemia Research Articles

Remission rate, toxicity and pharmacokinetics of venetoclax-based induction regimens in untreated pediatric acute myeloid leukemia

The efficacy and safety of venetoclax in newly diagnosed pediatric acute myeloid leukemia (AML) are not well-established as they are in adults. Children newly diagnosed with AML were recommended for induction therapy with venetoclax and chemotherapy or hypomethylating agents (HMAs) as per for the ChiCTR1900027146 trial. Venetoclax was administered at a consistent dose of 200 mg/m2/day for 28 days, with adjustments when used concurrently with azoles. The study measured both the remission rates and the safety assessments of venetoclax. We enrolled 45 newly diagnosed pediatric patients with AML. The complete remission rates were 94.7% in the low/middle-risk group and 80.8% in the high-risk group; MRD-negative rates were 52.6% and 38.5% in the low/middle-risk group and high-risk group, respectively. Venetoclax based combination therapy was well tolerated by the majority of patients. The median duration of venetoclax dosing was 18 days (range 9–28), with hematological toxicity and infection being the most common adverse events. Venetoclax-based induction regimens demonstrated a high response rate and safety profile in newly diagnosed pediatric AML cases. This underscores the significance of venetoclax as a viable treatment option for untreated AML, extending beyond its role as salvage therapy for refractory/relapsed AML.

Ex vivo venetoclax sensitivity predicts clinical response in acute myeloid leukemia in the prospective VenEx trial

AbstractThe BCL2 inhibitor venetoclax has shown promise for treating acute myeloid leukemia (AML). However, identifying patients likely to respond remains a challenge, especially for those with relapsed/refractory (R/R) disease. We evaluated the utility of ex vivo venetoclax sensitivity testing to predict treatment responses to venetoclax-azacitidine in a prospective, multicenter, phase 2 trial conducted by the Finnish AML Group (VenEx, NCT04267081). The trial recruited 104 participants with previously untreated (n = 48), R/R (n = 39), or previously treated secondary AML (sAML) (n = 17). The primary end point was complete remission or complete remission with incomplete hematologic recovery (CR/CRi) rate in ex vivo sensitive trial participants during the first 3 therapy cycles. The key secondary end points included the correlations between ex vivo drug sensitivity, responses, and survival. Venetoclax sensitivity was successfully assessed in 102 of 104 participants, with results available within a median of 3 days from sampling. In previously untreated AML, ex vivo sensitivity corresponded to an 85% (34/40) CR/CRi rate, with a median overall survival (OS) of 28.7 months, compared with 5.5 months for ex vivo resistant patients (P = .002). For R/R/sAML, ex vivo sensitivity resulted in a 62% CR/CRi rate (21/34) and median OS of 9.7 versus 3.3 months for ex vivo resistant patients (P < .001). In univariate and multivariate analysis, ex vivo venetoclax sensitivity was the strongest predictor for a favorable treatment response and survival. The VenEx trial demonstrates the feasibility of integrating ex vivo drug testing into clinical practice to identify patients with AML, particularly in the R/R setting, who benefit from venetoclax.

Feasibility of Azacitidine and Venetoclax Followed by High/Intermediate Dose Cytarabine (HIDAC/IDAC) Consolidation in Previously Untreated Acute Myeloid Leukemia Patients Unfit for Intensive Chemotherapy in a Resource Constraint Low-Middle Income Country: A Pilot Study

Feasibility of Azacitidine and Venetoclax Followed by High/Intermediate Dose Cytarabine (HIDAC/IDAC) Consolidation in Previously Untreated Acute Myeloid Leukemia Patients Unfit for Intensive Chemotherapy in a Resource Constraint Low-Middle Income Country: A Pilot Study

AML-703 Feasibility of Azacitidine and Venetoclax Followed by High/Intermediate Dose Cytarabine (HIDAC/IDAC) Consolidation in Previously Untreated Acute Myeloid Leukemia Patients Unfit for Intensive Chemotherapy in a Resource Constraint Low-Middle Income Country: A Pilot Study

AML-703 Feasibility of Azacitidine and Venetoclax Followed by High/Intermediate Dose Cytarabine (HIDAC/IDAC) Consolidation in Previously Untreated Acute Myeloid Leukemia Patients Unfit for Intensive Chemotherapy in a Resource Constraint Low-Middle Income Country: A Pilot Study

Clinical Study of Venetoclax Combined with Azacitidine in the Treatment of Patients with Adult Acute Myeloid Leukemia

To evaluate the efficacy and side effects of venetoclax combined with azacitidine chemotherapy in the treatment of previously untreated adult patients with acute myeloid leukemia(AML). A retrospective analysis was performed on 48 untreated adult AML patients admitted to the Department of Hematology, Affiliated Hospital of Jinggangshan University from January 2020 to December 2022. Among them, 26 patients received venetoclax combined with azacitidine chemotherapy (observation group), and 22 patients received daunorubicin plus cytarabine chemotherapy (control group). The differences in complete response (CR) rate, objective response rate (ORR), progressionfree survival (PFS), overall survival(OS) and adverse reactions (AR) were compared between the two groups. There was no significant difference in age, sex ratio, absolute value of trilineage cell and proportion of bone marrow primordial cells between the two groups before treatment (all P >0.05). The CR rate and the ORR rate of the observation group was significantly higher than that of the control group (P < 0.05). After treatment, there were no significant difference in the adverse reactions such as myelosuppression, granulocytosis, secondary infection, mucosal damage, liver and kidney damage, cardiotoxicity and gastrointestinal toxicity between the two groups (P >0.05). The median PFS and the median OS of the observation group were significantly better than those of the control group (P < 0.05). The remission rate of venetoclax combined with azacitidine was higher than that of conventional chemotherapy in previously untreated adult acute myeloid leukemia. Venetoclax combined with azacitidine chemotherapy could reduce hematologic related side reactions and prolong the remission period and survival of AML patients.

Intensive induction chemotherapy vs hypomethylating agents in combination with venetoclax in NPM1-mutant AML

AbstractAlthough intensive induction chemotherapy (IC) remains the standard of care for younger patients with acute myeloid leukemia (AML), hypomethylating agents + venetoclax (HMA/VEN) can lead to durable remission among older patients with nucleophosmin 1 (NPM1) mutations. Whether IC or HMA/VEN is superior in patients aged ≥60 years with NPM1-mutant AML is unknown. We performed an international, multicenter retrospective cohort study of 221 patients (147 IC and 74 HMA/VEN) with previously untreated NPM1-mutant AML. Composite complete remission (cCR) (defined as CR + CR with incomplete count recovery) rate was similar for IC and HMA/VEN (cCR, 85% vs 74%; P = .067). Although overall survival (OS) was favorable with IC in unselected patients compared with HMA/VEN (24-month OS, 59% [95% confidence interval (CI), 52-69%] vs 38% [95% CI, 27-55%]; P = .013), it was not statistically different among patients aged 60-75 years (60% [95% CI, 52-70%] vs 44% [95% CI, 29-66%]; P = .069) and patients who received an allogeneic stem cell transplant (70% [95% CI, 58-85%] vs 66% [95% CI, 44-100%]; P = .56). Subgroup analyses suggested that patients with normal cytogenetics (24-month OS, 65% [95% CI, 56-74%] with IC vs 40% [95% CI, 26-60%] with HMA/VEN; P = .009) and without FLT3 internal tandem duplication mutations might benefit from IC compared with HMA/VEN (24-month OS, 68% [95% CI, 59-79%] vs 43% [95% CI, 29-63%]; P = .008). In multivariable analysis, OS was not statistically different between patients treated with IC and HMA/VEN (hazard ratio for death with HMA/VEN vs IC, 0.71; 95% CI, 0.40-1.27; P = .25).

EE523 Costs Per Responder With Venetoclax in Combination With Azacitidine in Unfit Patients With Previously Untreated Acute Myeloid Leukemia in China

EE523 Costs Per Responder With Venetoclax in Combination With Azacitidine in Unfit Patients With Previously Untreated Acute Myeloid Leukemia in China

EE411 Cost-Effectiveness of Venetoclax in Combination with Azacitidine in Unfit Patients With Previously Untreated Acute Myeloid Leukemia in China

EE411 Cost-Effectiveness of Venetoclax in Combination with Azacitidine in Unfit Patients With Previously Untreated Acute Myeloid Leukemia in China

Association between class III obesity and overall survival in previously untreated younger patients with acute myeloid leukemia enrolled on SWOG S1203.

There has been ongoing debate on the association between obesity and outcomes in acute myeloid leukemia (AML). Currently few studies have stratified outcomes by class I obesity, class II obesity, and class III obesity, and a more nuanced understanding is becoming increasingly important with the rising prevalence of obesity. We examined the association between body mass index (BMI) and outcomes in previously untreated AML in younger patients (age ≤60) enrolled in SWOG S1203 (n = 729). Class III obesity was associated with an increased rate of early death (p = 0.004) and worse overall survival (OS) in multivariate analysis (hazard ratio (HR) 2.48, 95% confidence interval (CI) 1.62-3.80 versus normal weight). Class III obesity was also associated with worse OS after allogeneic hematopoietic cell transplant (HR 2.37, 95% CI 1.24-4.54 versus normal weight). These findings highlight the unique risk of class III obesity in AML, and the importance of further investigation to better characterize this patient population.

Correlation between number of molecular mutations and outcomes in de novo acute myeloid leukemia.

e18513 Background: Genomic sequencing of cancer has led to a deeper genetic understanding of the pathogenesis of acute myeloid leukemia (AML). Studies in myelodysplastic syndrome have shown that as the number of oncogenic mutations increases, patient outcomes progressively worsen. We hypothesized that patients with AML may also have a worse prognosis if they have a higher number of somatic mutations. To test this hypothesis, we examined the somatic mutational profile of 225 patients with previously untreated AML. Methods: A single-center retrospective analysis was done utilizing the cancer registry and evaluated patients with de novo AML diagnosed between January 2015 to January 2021. Patient characteristics, cytogenetics, and molecular data were collected by chart review. Patients with available cytogenetic and somatic mutations profile from next-generation sequencing (NGS) were included. Clinically significant (CS) mutations for AML were detected by NGS performed on the diagnostic bone marrow specimen. Statistical analysis was done using the Mann-Whitney U test for continuous variables and proportions were compared using Chi-square test. Results: A total of 225 De Novo AML patients met inclusion criteria. The median age at diagnosis was 61 (range, 21-86). The population was fairly distributed among males (52%) and females (48%). Approximately 51% (n=115) of patients had 0-2 mutations, 43% (n=97) had 3-5 mutations, and 6 % (n=13) had &gt;5 CS mutations. The median number of CS mutations for the entire cohort was 2 (range: 0-9). Survival was worse in the group with &gt;5 mutations when compared to those with 5 or less mutations (23 vs 7 months, p= 0.012). Patients with intermediate risk cytogenetics had a higher median number of CS mutations compared to the favorable and adverse risk group combined (3 versus 1, p &lt; 0.001). To determine whether overall survival was impacted by the presence of an adverse mutation, a subgroup analysis was done using 43 patients with a normal karyotype and at least 1 adverse mutation. The cohort with &gt;5 CS mutations had a significantly shorter OS compared to patients with ≤5 CS mutations (43 vs 9 months, p= 0.001). Conclusions: We found that patients with intermediate-risk cytogenetics have a high number of CS mutations. We found that a higher number of mutations (&gt;5) led to statistically significant difference in survival. To determine whether this difference in survival was a result of the presence of adverse risk mutations vs. number of mutations alone, we analyzed our patients who had normal karyotype with at least one adverse genetic mutation and stratified them based on number of mutations. The presence of more than 5 CS mutations was associated with a worse OS. The number of clinically significant mutations may be an independent predictor of overall survival in AML. This can serve as another tool in stratifying AML risk with normal karyotype. A large prospective clinical trial is necessary to validate.

Efficacy and safety of venetoclax-based combination therapy for previously untreated acute myeloid leukemia: a meta-analysis

ABSTRACT Purpose: To explore the efficacy and safety of venetoclax-based combination therapy for older patients with newly diagnosed acute myeloid leukemia (AML). Methods: We performed a systematic review and meta-analysis of clinical trials comparing venetoclax plus hypomethylating agents (HMAs) or low-dose cytarabine (LDAC) with mono-HMAs or LDAC. The random or fixed effects model was applied to the studies based on heterogeneity. Dichotomous data were summarized using the risk ratio (RR) and 95% confidence interval (CI). Continuous variable data were reported as weighted mean differences (WMDs). Results: Nine studies, including a total of 1232 patients, were included in this meta-analysis. Thec complete remission (CR)/complete remission with incomplete hematological recovery (CRi) rate of the venetoclax (Ven) + azacytidine (Aza) group was significantly greater than that of the Aza monotherapy group (RR: 2.42; 95% CI: 1.85–3.15; P < 0.001). Similarly, the CR/CRi rate of the Ven + LDAC group was also significantly greater than that of the LDAC monotherapy group (RR: 2.57; 95% CI: 1.58–4.17; P = 0.00). The same results were observed for OS among these groups. However, the incidence of febrile neutropenia was greater in the Ven + Aza group than in the Ven + Decitabine (Dec) or monotherapy Aza group (RR: 0.69; 95% CI: 0.53–0.90; P = 0.006 and RR: 2.19; 95% CI: 1.58–3.03; P < 0.001, respectively). In addition, the Ven + LDAC group had significantly greater rates of constipation, diarrhea, nausea, and vomiting than the LDAC monotherapy group, with RRs and CIs of 0.61 (95% CI 0.44–0.83, P = 0.002), 1.81 (95% CI 1.22–2.67, P = 0.003), 1.39 (95% CI 1.06–1.82, P = 0.016), and 1.80 (95% CI 1.19–2.72, P = 0.005), respectively. Conclusion: Venetoclax combined with azacitidine, decitabine, or LDAC significantly improved the CR/CRi and OS of patients with previously untreated AML. However, venetoclax plus azacitidine or LDAC was more likely to lead to increased febrile neutropenia and gastrointestinal toxicity.

Efficacy of Venetoclax and Azacitidine in Acute Myeloid Leukemia Compared to Azacitidine Monotherapy: Real-World Experience.

The combination of venetoclax (VEN) and azacitidine (AZA) (VEN+AZA) leads to higher complete remission rates and longer overall survival (OS) in patients with untreated acute myeloid leukemia (AML) who are ineligible for intensive combination chemotherapy. In practice, the doses of VEN and AZA are reduced at the attending physician's discretion to avoid adverse events; however, the impact of dose and duration reductions has not been fully clarified. We analyzed whether the efficacy was maintained with reduced VEN+AZA compared to AZA monotherapy in the real world. A total of 33 patients were included; 17 (10 newly diagnosed, 7 primary refractory or relapsed) received VEN+AZA, and 16 (7 newly diagnosed, 9 primary refractory or relapsed) received AZA. We analyzed complete remission (CR) and CR with incomplete hematologic recovery (CRi) rates, OS, and the incidence of adverse events. CR/CRi were achieved in 7/17 (41.2%) and 11/17 (64.7%) patients in the VEN+AZA group and 0/15 (0%) and 2/15 (6.7%) patients in the AZA group, respectively. The CR/CRi rate was higher in the VEN+AZA group than in the AZA group (p=0.001). OS was longer in the VEN+AZA group than in the AZA group (p=0.03), with a median of 506 days [95% confidence interval (CI)=234-585 days] and 208 days (95% CI=52-343 days), respectively. The doses of the VEN+AZA combination were reduced at the attending physician's discretion, resulting in a higher CR/CRi rate and longer OS than AZA monotherapy and is considered useful for AML in the real world.

Differential co-expression network analysis elucidated genes associated with sensitivity to farnesyltransferase inhibitor and prognosis of acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous disease and the most common form of acute leukemia with a poor prognosis. Due to its complexity, the disease requires the identification of biomarkers for reliable prognosis. To identify potential disease genes that regulate patient prognosis, we used differential co-expression network analysis and transcriptomics data from relapsed, refractory, and previously untreated AML patients based on their response to treatment in the present study. In addition, we combined functional genomics and transcriptomics data to identify novel and therapeutically potential systems biomarkers for patients who do or do not respond to treatment. As a result, we constructed co-expression networks for response and non-response cases and identified a highly interconnected group of genes consisting of SECISBP2L, MAN1A2, PRPF31, VASP, and SNAPC1 in the response network and a group consisting of PHTF2, SLC11A2, PDLIM5, OTUB1, and KLRD1 in the non-response network, both of which showed high prognostic performance with hazard ratios of 4.12 and 3.66, respectively. Remarkably, ETS1, GATA2, AR, YBX1, and FOXP3 were found to be important transcription factors in both networks. The prognostic indicators reported here could be considered as a resource for identifying tumorigenesis and chemoresistance to farnesyltransferase inhibitor. They could help identify important research directions for the development of new prognostic and therapeutic techniques for AML.

Safety, Pharmacodynamic, and Anti-Tumor Activity of SL-172154 As Monotherapy and in Combination with Azacitidine (AZA) in Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML) and Higher-Risk Myelodysplastic Syndromes/Neoplasms (HR-MDS) Patients (pts)

Background: CD47 blocking antibodies and SIRPα-Fc fusion proteins have demonstrated activity in combination with azacitidine (AZA) in previously untreated (UnTx) HR-MDS and AML pts. SL-172154 (SIRPα-Fc-CD40L), a hexameric, bi-functional fusion protein consisting of SIRPα domains linked to CD40L domains through an inert Fc linker demonstrated improved anti-tumor activity in comparison to naked CD47 blocking antibodies in pre-clinical studies [de Silva et al. Cancer Immunol Res 2020]. SL-172154, as a CD47 inhibitor, requires combination with AZA to enhance pro-phagocytic signals on leukemic stem cells/blasts thereby potentiating macrophage phagocytosis in AML/HR-MDS. Here we report the results from the Phase 1 Dose Escalation. cohorts for SL-172154 monotherapy [SL-mono] and for SL-172154 + AZA combination [SL-AZA] in pts with HR-MDS or AML. Methods: The objectives of the dose escalation cohorts include evaluation of safety, dose-limiting toxicity (DLT), recommended phase 2 dose, pharmacokinetic and pharmacodynamic effects and efficacy per IWG 2006 for MDS and ELN 2017 for AML. SL-172154 was administered IV weekly of a 28-day cycle as monotherapy or with AZA 75 mg/m 2 for 7 days per cycle. mTPI-2 was used for dose escalation with a DLT threshold of 20%. Pts ≥ 18 years old with R/R HR-MDS or R/R AML were eligible for dose escalation cohorts. In addition, UnTx pts with TP53 mutant (TP53m)-MDS were eligible for SL-AZA cohorts. Results: As of May 25, 2023, 37 pts were enrolled (19 in SL-mono; 18 in SL-AZA cohorts): 14 women; median age 70 years [range 44-81]. 27 pts had R/R AML (16 de novo; 11 secondary), 5 had R/R MDS, and 5 were UnTx TP53m-MDS. 23 (85%) of 27 R/R AML pts had adverse genetic abnormalities per 2017 ELN classification, including 9 (33%) with TP53m or del 17. The median number of prior lines of AML therapy was 2 [range 1-4]; 25 (93%) had received venetoclax (VEN) and 23 (85%) had received a hypomethylating agent (HMA). All 5 pts with R/R MDS had previously received HMA and 2 pts were previously treated with VEN. SL-172154 was dose escalated as monotherapy or with AZA as shown in Table 1. Infusion-related reactions (IRRs) were the most common SL-172154-related treatment-emergent AEs (TEAEs) reported in 13 (68%) and 8 (44%) pts in SL-mono and SL-AZA cohorts, respectively. IRRs (51 events) were Grade (G) 1 or 2 except for 3 G3 events (1 each at 6 mg/kg SL-mono and SL-AZA; 1 at 3 mg/kg SL-mono). Other SL-172154-related TEAEs observed in ≥ 3 pts were AST increased (4; 21%), ALT increased (3; 16%) and nausea (3; 17%) in SL-mono cohorts, and nausea (3; 17%) in SL-AZA cohorts. All events of AST/ALT increased were transient. Only one DLT (G3 IRR in the 6 mg/kg SL-AZA cohort) was reported, which required a dose reduction to 3 mg/kg. As of July 10, 2023, in SL-mono cohorts, 1 pt with R/R AML post 7+3, FLAG and VEN/AZA achieved Morphologic Leukemia-Free State (blast reduction from 19% to &amp;lt;5%) after 1 cycle of 6 mg/kg SL-172154 and proceeded to allogeneic hematopoietic cell transplant (allo-HCT) after cycle 2. In 12 evaluable pts with R/R AML receiving SL-AZA, although no objective responses (OR) were observed, relative reduction in bone marrow (BM) blasts from baseline was reported in 2/5 pts at 1 mg SL-AZA (-50%, -75%) and 5/7 pts at 3 mg SL-AZA (ranging from -35% to -90%). One pt underwent an allo-HCT. In 4 evaluable pts with UnTx TP53m-MDS, the ORs were 1 complete remission (CR), 1 marrow CR, and 2 stable disease. 2 of them proceeded to allo-HCT. SL-172154 induced elevations in serum IL-12p40, IP-10, IL-8, IL-10, MIP3α and MCP1: greater response at 3 mg/kg compared to 1 mg/kg while similar between 3 and 6 mg/kg. In the BM, SL-172154 induced a dose-dependent increase in phagocytic cells (CD11b, HLA-DR, CD16, CD36 and CD64) within mature myeloid immune cell compartments (CD45highCD34-). Reduction in leukemic blasts (CD45lowCD34+) was associated with an increase in mature myeloid and phagocytic cell phenotypes (3 mg/kg SL-AZA &amp;gt; 1 mg/kg SL-AZA). Conclusions: SL-172154 was well tolerated up to 3 mg/kg as monotherapy and in combination with AZA. Preliminary efficacy signals were detected in UnTx TP53m-MDS and R/R AML. A response to SL-172154 monotherapy, dose-dependent increases in serum cytokines and accumulation of mature myeloid cells in BM suggest a potential role for CD40 stimulation. Based on the safety, preliminary efficacy and pharmacodynamic activity, 3 mg/kg SL-172154+ AZA is being evaluated in treatment naïve pts with TP53m AML and HR-MDS.

Correlation between Number of Molecular Mutations and Outcomes in De Novo Acute Myeloid Leukemia

Introduction Genomic sequencing of cancer has led to a deeper genetic understanding of the pathogenesis of acute myeloid leukemia (AML). Studies in myelodysplastic syndrome have shown that as the number of oncogenic mutations increases, patient outcomes progressively worsen. We hypothesized that patients with AML may also have a worse prognosis if they have a higher number of somatic mutations. To test this hypothesis, we examined the somatic mutational profile of 225 patients with previously untreated AML. Methods A single-center retrospective analysis was done utilizing the Kentucky Cancer Registry (KCR) and evaluated patients with de novo AML diagnosed between January 2015 to January 2021. Patient characteristics, cytogenetics, and molecular data were collected by chart review. Patients with available cytogenetic and somatic mutations profile from next-generation sequencing (NGS) were included. Clinically significant (CS) mutations for AML were detected by NGS performed on the diagnostic bone marrow specimen. The list of clinically significant mutations was obtained from My Cancer Genome and was compared to the mutations present in our patients. Statistical analysis was done using the Mann-Whitney U test for continuous variables and proportions were compared using Chi-square test. Overall survival (OS) was calculated by the Kaplan-Meier method and compared using a log-rank test. P value was considered significant if &amp;lt; 0.05. Results A total of 225 De Novo AML patients met inclusion criteria. The median age at diagnosis was 61 (range, 21-86). The population was fairly distributed among males (52%) and females (48%). Approximately 51% (n=115) of patients had 0-2 CS mutations, 43% (n=97) had 3-5 mutations, and 6 % (n=13) had &amp;gt; 5 CS mutations. The median number of CS mutations for the entire cohort was 2 (range: 0-9). Survival was worse in the group with &amp;gt;5 mutations when compared to those with 5 or less mutations (23 vs 7 months, p= 0.012, Figure 1). When analyzing the number of CS mutations per cytogenetic group, those with intermediate risk cytogenetics had a higher median number of CS mutations compared to the favorable and adverse risk group combined (3 versus 1, p &amp;lt; 0.001). In patients with &amp;gt; 5 CS mutations, 11/13 had a mutation associated with an adverse prognosis. To determine whether overall survival was impacted by the presence of an adverse mutation, a subgroup analysis was done using 43 patients with a normal karyotype and at least 1 adverse mutation. The cohort with &amp;gt; 5 CS mutations had a significantly shorter OS compared to patients with ≤ 5 CS mutations (43 vs 9 months, p= 0.001, Figure 2). Conclusion In summary, we found that patients with intermediate-risk cytogenetics have a high number of CS mutations. When patients were stratified by number of mutations, we found that a higher number of mutations (&amp;gt;5) led to statistically significant difference in survival compared to those with ≤5 mutations. To determine whether this difference in survival was a result of the presence of adverse risk mutations vs. number of mutations alone, we analyzed our patients who had normal karyotype with at least one adverse genetic mutation and stratified them based on number of mutations. The presence of more than 5 CS mutations was associated with a worse OS compared to ≤ 5 mutations. It appears that the number of clinically significant mutations may be an independent predictor of overall survival in AML. This can serve as another tool in stratifying AML risk with normal karyotype. This finding will need to be validated in a large prospective clinical trial.

Acute Myeloid Leukemia Driven IL-3 Dependent Upregulation of BCL-2 in Non-Malignant Hematopoietic Progenitor Cells Increases Venetoclax Induced Cytopenias

The BH3 mimetic venetoclax, in combination with low dose cytarabine, decitabine or azacitidine has shown clinical efficacy in newly diagnosed acute myeloid leukemia (AML) (1, 2). This has been a significant advance, particularly in the treatment of older AML patients, and those who are ineligible for intensive chemotherapy, who historically have been difficult to treat. Venetoclax selectively inhibits the BCL-2 protein which is overexpressed in AML in order to activate intrinsic apoptosis. However, this treatment regime is associated with cytopenias including neutropenia, febrile neutropenia, and thrombocytopenia which leaves patients immunocompromised (3). The underlying cause of cytopenias in the context of venetoclax-treated AML remains unexplained. Here we describe a mechanism for venetoclax-induced cytopenias in AML. Two established AML models were used to assess BCL-2 expression profile in HPCs. Isolated LSK cells were co-cultured with mouse AML (HOXA9/Meis1 or MN1 overexpressing cells). RT-qPCR analysis identified BCL-2 upregulation in LSKs co-cultured with both AML cell types. To understand the significance of this in vivo, MN1 cells were engrafted into C57BL/6 mice and LSKs were FACS purified. Analysis confirmed increased BCL-2 gene and protein expression by RT-qPCR and flow cytometry when compared to control LSKs. Next, to recapitulate the clinical cytopenias, MN1 engrafted mice or control mice were treated with venetoclax for 7 days by oral gavage. Flow cytometry analysis of bloods and bone marrow in venetoclax-treated AML mice determined neutrophil depletion and reduced numbers of HPCs, namely LSK, MPP, HSC and GMP, compared to untreated AML mice . Todetermine the mechanism of BCL-2 upregulation in LSKs we explored various signalling pathways using targeted inhibitors on LSKs cultured with MN1 conditioned media. Using this method, we established that interleukin 3 (IL-3) activates BCL-2 transcription in LSKs leading to a dependency on pro-survival BCL-2 protein. Furthermore, treatment of LSKs, cultured in MN1 conditioned media with IL-3 neutralising antibody MP2-8F8 reduced BCL-2 gene and protein expression in LSKs. Finally, MN1 engrafted mice were treated with venetoclax and IL-3 neutralising antibody in combination which restored neutrophil levels to numbers observed in untreated AML mice. Here, we demonstrate that BCL-2 is overexpressed in non-malignant HPCs during AML progression using two AML models. In addition, using our syngeneic mouse model we show that venetoclax induces HPC depletion. In vitro studies confirm that IL-3 mediates BCL-2 upregulation in HPCs - this sensitises HPCs to venetoclax and causes cytopenias. We also demonstrate that neutrophils can be recovered using IL-3 neutralisation in combination with venetoclax in AML engrafted mice. Taken together, these findings provide biologic insight for IL-3 inhibition alongside venetoclax to reduce the incidence of cytopenias observed in elderly AML patients.

Serum Amyloid A1 (SAA1) Secreted By the Stromal Microenvironment Drives Malignant Clonal Proliferation in Myelodysplastic Syndromes (MDS) and Acute Myeloid Leukemia (AML)

Drivers of malignant hematopoietic stem cell clonal proliferation from age-related clonal hematopoiesis (ARCH) to Myelodysplastic Syndromes (MDS) and Acute Myeloid Leukemia (AML) are not well understood. However, a pro-inflammatory and immune tolerant aging bone marrow (BM) microenvironment is thought to contribute to disease development. Serum Amyloid A1 (SAA1) has been identified as a novel pro-inflammatory oncoprotein the levels of which progressively increase with MDS and AML progression. SAA1 also selectively promotes growth of patient-derived MDS and AML cells independent of cytogenetic or mutational profile. We aimed to characterize the mechanism by which SAA1 drives oncogenesis within the microenvironment. Herein we further stratified the disease marking properties of SAA1 by clarifying the association of its BM levels with disease progression in MDS and AML. SAA1 levels were significantly elevated in BM aspirates from MDS and AML patients as compared to those from healthy age-matched subjects (p=0.0002 and p=0.0052, respectively). The effects of SAA1 on mutated hematopoietic cells were assessed in a model of age-related clonal hematopoiesis (ARCH). Utilizing a CRISPR-Cas9 system, ASXL1-mutant CD34+ hematopoietic stem cells (HSCs) were generated; the replating capacity of both mutated and healthy CD34+ cells were assessed in the presence or absence of SAA1. Notably, SAA1 increased the replating capability assessed by an increase in the number of colonies formed on serial replating of ASXL1-mutant CD34+ cells, but not those of SAA1-treated healthy CD34+ or vehicle treated ASXL1-mutated CD34+ cells, suggesting that the presence of SAA1 favors stemness of mutated HSCs, and implicating SAA1 as a driver of malignant clonality. To investigate the mechanism of action of SAA1 BM mononuclear cells from AML patients or healthy age-matched subjects were treated with SAA1 or vehicle overnight and single-cell RNA sequencing analysis was performed. Seurat and cell cluster annotation analysis showed that AML samples treated with SAA1 had increased numbers of hematopoietic stem and progenitor cells (HSPCs) and plasmacytoid dendritic cells as compared to matched untreated AML samples. Further, Enrichr analysis showed that pathways upregulated by SAA1 in AML samples included pro-inflammatory molecules, anti-apoptotic, and antiviral defense mechanisms (p&amp;lt;0.0001). Shared genes upregulated in these pathways in HSPCs include interferon-induced signals including JAK2, STAT1, and OAS3, and genes implicated in resistance to chemotherapy, including CD44 and CD36, as well as the anti-phagocytosis signal CD47. Lastly, we initiated the development of a blocking monoclonal antibody against SAA1 as a means of inhibiting its potent oncogenic effects on malignant HSCs and examining its potential therapeutic activity. Utilizing a RAW 264.7 NFκB-luciferase reporter cell line, we screened 51 clones for their ability to selectively block SAA1-mediated NFκB activation. 7 optimal candidates were identified which demonstrated dose-dependent reduction in NFκB activity upon SAA1 challenge. Importantly, these candidate clones were specific for SAA1 and did not affect NFκB activation mediated by lipopolysaccharide (LPS)-mediated activation. We observed up to an 85% reduction of SAA1-mediated activity using supernatants from further subcloning of previously selected candidates. Moreover, cell proliferation of a human AML cell line (OCI-AML3) stimulated by SAA1 was markedly reduced in the presence of candidate antibodies, suggesting anti-proliferative activity. Our findings show that SAA1 levels correlates with disease severity in MDS and AML progression, selectively promotes stemness and proliferative potential of ASXL1-mutant cells, and demonstrates unique immune-related mechanisms selecting for malignant clonality. Further development and purification of a novel inhibitory antibody against SAA1 for future in vivo and ex vivo testing is underway as a promising novel target to reduce SAA1-mediated, niche-driven effects with broad implications in the treatment of hematological malignancies.

Type 3 Innate Lymphoid Cells Promote Acute Myeloid Leukemia Immune Evasion and Expansion

Acute Myeloid Leukemia (AML) is an aggressive myeloid malignancy originated in the bone marrow with poor overall survival rates of less than 30%. The immune system has been shown to play an important role in detecting and eliminating leukemic cells. Recent studies have described a population of immune cells termed Innate lymphoid cells (ILCs). ILCs are known to regulate both innate and adaptive immunity in an antigen-independent manner and are believed to be among the first immune cells to interact with malignantly transformed cells. Natural killer (NK) cells are a subset of ILCs and are known to inhibit AML progression, however the impact of other ILCs is not yet fully understood. Type 3 ILCs (ILC3s) have key roles in maintaining homeostasis in mucosal immunity through their ability to secrete cytokines including IL-17, IL-22, TNFα and GM-CSF (pro-myeloid). An expansion of ILC3s has recently been observed in solid tumors, however the overall functional impact of ILC3s in the setting of AML remains poorly understood and warrants further investigation. We first utilized an MLL-partial tandem duplication and FLT3-internal tandem duplication Flt3-ITD double knock-in mutation murine model of AML that recapitulates two clinically relevant mutations in human AML. Using this AML model, we discovered an expansion of ILC3s in the bone marrow of leukemic mice compared to wild-type control mice (2.364% +/- 0.40% AML vs 0.045% +/- 0.40% WT, n=5, p&amp;lt;0.0001). We also observed an increase in ILC3s in the bone marrow of untreated AML patients relative to age matched donor controls (7.013% +/- 2.6% vs. 2.328% +/- 2.6%). Our published data have previously shown AML blasts secrete aryl hydrocarbon receptor (AHR) ligands, which can bind and activate the transcription factor AHR in ILC precursors and mature ILCs. AHR is an important transcription factor in ILC3 development. Therefore, we hypothesized that the ILC3 increase was due at least in part to AHR-mediated increased ILC3 differentiation. To address this hypothesis, we isolated the ILC precursor (ILCP) from normal human donors and co-cultured with AML cells. By regulating AHR activity in this system, we showed that ILC3s are expanded in AML in part due to AML-mediated AHR activation (28.02% +/- 3.89% without AML, 60% +/- 5.5% with AML and 27% +/- 5% AML+AHR inhibitor, n=15, p&amp;lt;0.001). Next, we sought to determine the direct impact of ILC3s on AML proliferation and differentiation that could contribute to AML relapse. We utilized a colony forming assay (CFU) assay in the presence or absence of ILC3s. Bone marrow from primary untreated AML patients was cultured alone or with ILC3s (Lin-CD94-NKp44+). AML samples co-cultured with ILC3s had significantly increased colony formation relative to AML alone (69.4 CFU AML+ILC3 vs 42.7 CFU AML alone, n=8, p&amp;lt;0.05). Post-culture, we observed significant increases in the transcript of GM-CSF and TNFα in ILC3s co-cultured with AML marrow as compared to ILC3s alone. Furthermore, in our immunocompetent murine AML model, we observed significantly higher production of GM-CSF and TNFα by ILC3s in the bone marrow of leukemic mice relative to nonleukemic controls (GM-CSF: 11.08% +/- 1.6 AML vs 1.128% +/- 1.6 WT, n=10, p&amp;lt;0.0001; TNFα: 5.456% +/- 1.3 AML vs 1.307% +/- 1.3 WT, n=10, p&amp;lt;0.05), suggesting a potential mechanism of ILC3-mediated increased colony formation. Lastly, to determine if ILC3 expansion impacted NK cell immune surveillance, we co-cultured normal donor human ILC3s with AML cells, separated by transwell, for 48 hours before subjecting the AML cells to an NK cell cytotoxicity assay. We observed significantly reduced NK cell killing of AML cells when co-cultured with ILC3s compared to controls, suggesting ILC3s protect AML cells from NK cell-mediated killing (24.3% killing +/- 3.81% AML alone vs 14.57% +/- 1.35% AML with ILC3, n=18, p&amp;lt;0.01). Collectively, these data support a model in which AML-mediated AHR activation promotes ILC3 expansion to both support AML proliferation and protect AML blasts from immune surveillance. Future studies will focus in exploring how to target these interactions to design effective therapeutic approaches and improve patient clinical outcomes.

Trial in Progress: An Open Label Phase I/II, Multicenter Study Evaluating Safety, Pharmacokinetics and Efficacy of S65487, a BCL-2 Inhibitor Combined with Azacitidine in Adults with Previously Untreated Acute Myeloid Leukemia Ineligible for Intensive Treatment

Preclinical and clinical data support combining Bcl-2 inhibitors (Bcl-2i) with hypomethylating agents (HMAs) in the treatment of acute myeloid leukemia (AML). S65487, a potent intravenous Bcl-2i, has shown promising synergistic activity when combined with azacitidine against in vitro AML models. Based on those data, we initiated a Phase I/II multicenter study of S65487 combined with azacitidine for newly diagnosed patients aged 18 years or older with de novo or secondary AML ineligible for intensive chemotherapy in 6 countries in Europe and Asia (NCT04742101). Secondary AML was defined as those related to previous leukemogenic therapies or transformed from a myelodysplastic syndrome. Patients with AML originating from myeloproliferative disorders were excluded. Ineligibility to intensive chemotherapy was defined as age of at least 75 years or the presence of significant co-morbidities. Previous use of HMA was allowed in the first six dose levels tested in the Phase I portion of the study, but was excluded afterwards, including during the Phase II part. Other eligibility criteria were standard for this patient population. Each cycle of therapy lasts for 28 days. Subcutaneous or intravenous azacitidine is administered at a dose of 75mg/m 2 in 7 consecutive administrations per cycle starting on day (D) 1 with a 2-day interval during weekends. Three schedules of S65487 are planned to be tested during the Phase I part to increase its concurrent administration with azacitidine and their synergism. Schedule 1 consists of weekly administrations (doses on D1, 8, 15, and 22). Two more intensified schedules consist of S65487 administration on D1, D3, D5, D8 (schedule 2) or D1 through D5, D8, and D9 (schedule 3) on the same days of azacitidine dosing. S65487 is administered over 30 minutes. When administered on the same day, S65487 is given first followed by azacitidine within 30 to 60 minutes. Treatment should be discontinued due to disease progression, or if other standard withdrawal criteria are met. The Phase I portion of the study follows a standard design guided by an adaptive Bayesian Logistic Regression Model with overdose control to estimate the maximum tolerated dose (MTD) based on the occurrence of dose-limiting toxicities during cycle 1. Patient accrual for the Phase I portion of this study is ongoing. The planned testing of schedule 1 is limited due to the expected low synergism with azacitidine. Once the recommended Phase II dose (RP2D) or MTD are established for schedules 2 and 3, the Phase II part will start and will be comprised of a maximum of two cohorts, each containing up to 27 patients. A Bayesian optimal design based on complete remission rate will guide the Phase II. Interim futility analyses are planned after enrollment of 10 and 20 evaluable patients. Randomization will not be used to allocate patients to one of the two cohorts planned during the Phase II portion of the study. The primary objective during the Phase I is to determine the safety, tolerability, and the RP2D or MTD of S65487 in combination with azacitidine. The primary objective of the Phase II is to assess the efficacy of this therapy. Pharmacokinetic analyses are included as secondary objectives in both parts of the study. Measurable residual disease will be assessed as a secondary objective in the Phase II part using a well validated, standard flow-cytometry panel. Pharmacodynamic analyses are conducted as exploratory objectives in both parts of the study. In particular, the disruption of the BCL2/BIM complex is followed in peripheral-blood mononuclear cells to guide the estimation of the RP2D.

Tumor Lysis Syndrome in Patients with AML Initiated on Venetoclax-Based Treatment without a Dose Ramp-up

Introduction Treatment with the combination of a hypomethylating agent (HMA) and venetoclax (VEN) is the standard of care for older patients (pts) with acute myeloid leukemia (AML). Venetoclax, an oral BCL-2 inhibitor, was initially approved for the treatment of chronic lymphocytic leukemia (CLL). In the early, pivotal studies assessing VEN safety, tumor lysis syndrome (TLS) was found to be a dose-limiting, potentially fatal toxicity. Dosing modifications were made to allow for safer initiation of the drug and, ultimately, a dose ramp-up was included in the dosing recommendation for CLL. Given the risk for TLS with VEN initiation for CLL, it was hypothesized that the risk would be the same, or potentially greater, when treating pts with AML. Therefore, studies of VEN in AML have included a dose ramp-up. Although reported rates of tumor lysis syndrome in these studies have been much lower than expected, a dose ramp-up for pts with AML is included in the package insert for VEN and continues to be utilized in clinical trials. Methods We conducted a retrospective analysis of pts ≥18 years of age with newly diagnosed or relapsed/refractory AML treated with a standard dose hypomethylating agent (HMA), either azacitidine or decitabine, and VEN without a dose ramp-up (initiated at 400mg daily or 100mg daily if on concomitant voriconazole or posaconazole) at Thomas Jefferson University Hospital from January 1, 2018- August 1, 2021. The primary objective of this study was to determine the rate of laboratory and clinical TLS within 72 hours after chemotherapy initiation, as defined by the Cairo-Bishop criteria (Table 1). The secondary objectives were (1) to identify clinical and laboratory risk factors for the development of TLS in pts with AML who were treated with HMA-VEN without a VEN dose ramp-up and (2) to compare rates of TLS in pts with AML who were treated with HMA-VEN without a VEN dose ramp-up to historical rates of TLS in pts who underwent a VEN dose ramp-up. In the Phase 3 study of azacitidine and venetoclax the rate of TLS during the VEN dose ramp-up period (days 1-3 of treatment) was 1% (DiNardo CD, Jonas BA, Pullarkat V, et al. Azacitidine and venetoclax in previously untreated acute myeloid leukemia. N Engl J Med. 2020;383(7):617-629.). Results Ninety pts were included in the analysis. Seventy-one pts had newly diagnosed AML and 19 had relapsed/refractory disease. The majority of pts (58/90, 64%) had adverse risk disease by 2017 European LeukemiaNet Criteria. Median baseline white blood cell count at the time of therapy initiation was 3.25 (range 0.5-161.4). Sixty-one pts (68%) were receiving allopurinol prophylaxis at the time of HMA-VEN administration. Eighteen pts (20%) had a history of underlying renal disease. Fifteen pts (17%) were on medications, such as thiazide diuretics, aspirin, or levodopa, that can increase the risk of TLS at the time of treatment. Zero pts met the defined criteria for laboratory or clinical TLS. One pt developed acute kidney injury and one pt developed a cardiac arrhythmia (atrial fibrillation) but neither had concomitant evidence of laboratory TLS. Discussion In this retrospective study of 90 pts with newly diagnosed or relapsed/refractory AML who were treated with HMA-VEN without a VEN dose ramp-up no pts developed clinical or laboratory tumor lysis syndrome. This is comparable to the rate of TLS (1%) seen in the registration trial of HMA-VEN where pts were treated with VEN 100 mg on day 1, 200 mg on day 2, and 400 mg on day 3 and thereafter. Starting pts with AML on full dose VEN on day 1, regardless of white blood cell count, renal function, or concomitant medications, appears safe and could be implemented in clinical practice and clinical trials moving forward. This would simplify dosing for pts, pharmacists, and providers and allow for easier initiation of therapy.