Advanced Acute Myeloid Leukemia Research Articles

Comparison of low dose cytosine arabinoside, azacitidine and azacitidine venetoclax combination treatment as remission induction in elderly acute myeloid leukemia patients

Aims: Low-intensity therapies are widely preferred in the treatment of advanced age, fragile acute myeloid leukemia (AML) patients. In this study, we aimed to compare hematological recovery rates after first cycle chemotherapy and overall survival for advanced aged AML patients treated with azacitidine (AZA) or low dose cytosine arabinoside (LDCA) or venetoclax (Ven) with AZA combination.
 Methods: Ninety-one patients were retrospectively analyzed. 
 Results: Forty-one patients treated with LDCA, 30 patients treated with AZA and 20 patients treated with AZA+Ven were included in the study. Patients who received these three treatments and who achieved response and did not receive any other treatment during the follow-up period were included in the study. Median age at diagnosis was 70. The percentage of patients who achieved neutrophil recovery after the first cycle was 27%, 73% and 50% of the patients treated with LDCA, AZA and AZA+Ven respectively. The rate of patients who achieved platelet recovery was 60%, 80%, 70% respectively. Erythrocyte transfusion independency was 54% for LDCA patients, 73% for AZA patients and 60% for combination therapy. Overall survival was longer in patients receiving AZA+Ven than other treatment groups while grade 3-4 infections were more common in the first cycle of the treatment.
 Conclusion: According to our study, patients treated with AZA had better platelet and neutrophil recovery rates with also longer overall survival than patients treated with LDCA, but total overall survival was superior in AZA+Ven combination. Hypomethylating agents with venetoclax is a preferable treatment option in elderly AML patients.

Abstract 4950: Discovery of potent and selective CK1α molecular degrader with a favorable safety profile for acute myeloid leukemia and solid tumors

Abstract CK1α, an isoform of casein kinase 1 (CK1), promotes tumor growth by enhancing negative effects of MDM2 and MDMX on p53. Unlike other cancer types, the frequency of TP53 mutations is relatively low (< 20%) in acute myeloid leukemia (AML). Therefore, promoting apoptosis by activation of p53 pathway has been a promising strategy for treatment of AML with wild-type (WT) TP53. However, preclinical activities of p53 activators have not been fully translated into clinic, partly due to their on-target hematological toxicities. We hypothesized that inhibition of CK1α can be an alternative strategy. To develop a small molecule targeting CK1α, we identified a novel CK1α-selective molecular glue degrader (MGD), PIN-A1 through screening of compounds hijacking cereblon (CRBN) E3 ligase. Here, we report its robust pharmacological activities in various preclinical AML models as a single agent or in combination with other targeted therapies along with its superior safety profile to MDM2 inhibitors. First, we demonstrated PIN-A1 can form a ternary complex with CK1α and CRBN using TR-FRET assay. Selective degradation of CK1α by PIN-A1 was also confirmed by global proteomics analysis. PIN-A1 induced rapid degradation of CK1α in human AML MV-4-11 cells harboring WT TP53, followed by increasing the level of p53 protein and its downstream target genes, ultimately leading to apoptotic cell death. Consistent with these results, preferential sensitivity of AML cells with WT TP53 to the CK1α degrader was demonstrated in screening assay of broad panel of liquid cancer cell lines. When combined with other targeted therapies agents used for AML, PIN-A1 displayed strong synergistic effects in cell killing. To evaluate its pharmacological activity in vivo, PIN-A1 was tested in a xenograft model engrafted with MV-4-11 and a dissemination model of MOLM-14, respectively. Systemic administration of PIN-A1 alone resulted in robust antitumor activity consistent with > 90% CK1α degradation in tumor tissues, comparably achieved at a much lower dose in combo treatments. Importantly, animals remained tumor-free (5/8) in the MV-4-11 model or prolonged survival in the disseminated model even after they were no longer on the combination treatment of PIN-A1 with a targeted agent X. Lastly, while PIN-A1 had negligible effects on the viability of human PBMC with minimal activation of the p53 pathway at an efficacious dose range for MV-4-11 (Therapeutic index= 8,333), agent X induced p53 pathway and enhanced anti-leukemic activity to a similar extent in two cell types (Therapeutic index=4). Also, we found that the combination treatment of PIN-A1 with agent X had a substantial effect on several solid tumors driven by enhancing the stability and activity of p53. In summary, these results suggest that a CK1α MGD with its favorable safety profile has a potential to become an effective treatment option for advanced AML and solid tumors. Citation Format: Jinuk Kong, Jisu Park, Heekyu Lee, Hyunseok Kang, Deokjae Lee, Hyunsun Jo. Discovery of potent and selective CK1α molecular degrader with a favorable safety profile for acute myeloid leukemia and solid tumors. [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 4950.

Don't forget cord blood in non-remission acute myeloid leukaemia!

Transplantation from haploidentical donors is widely used, with progressive reduction of cord blood (CB) as alternative donor. The paper by Matsuda and colleagues, the largest analysing the outcome in non-remission acute myeloid leukaemia (AML) transplanted with haploidentical donor or CB, suggests that CB is still a viable option when considering allogeneic transplantation for advanced AML. Commentary on: Matsuda et al. Comparison of transplant outcomes between haploidentical transplantation and single cord blood transplantation in non-remission acute myeloid leukaemia: A nationwide retrospective study. Br J Haematol. 2023;201:106-113.

Predictors of Disease Progression and Survival in Patients with Myelodysplastic Syndrome Secondary to Inherited Bone Marrow Failure Syndromes

Introduction Inherited bone marrow failure syndromes (IBMFSs) are rare genetic disorders characterized by abnormal hematopoiesis resulting in cytopenias, risk of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Once patients develop MDS, the only cure is hematopoietic stem cell transplant (HSCT). Proceeding to HSCT before transformation to advanced MDS or AML leads to better outcomes (Smith et al., PBC 2013). The rate of disease progression from early MDS to advanced MDS or AML is variable and risk factors for progression in IBMFS patients are unknown. We hypothesized that certain variables could predict the likelihood of progression, and that the type of disease progression may impact overall survival (OS). Methods Data were collected from patients prospectively enrolled in the Canadian Inherited Marrow Failure Registry (CIMFR), a Canadian collaboration including >95% of pediatric IBMFS patients. Patients were diagnosed with a specific syndrome or unclassified IBMFS (ucIBMFS) based on published criteria. Diagnostic criteria for pediatric MDS defined by Cada et al. (Haematologica 2015) were used, patients with refractory cytopenia (RC) with or without dysplasia or ringed sideroblasts were included. Patients with refractory cytopenia with excess blasts (RCEB) were excluded. MDS progression was defined as 1 or more of: a new cytogenetic abnormality, more advanced cytopathology, worse cytopenias requiring HSCT. Variables evaluated included: involvement of specific organ systems, hematologic parameters within 3 months of cytogenetic clones/MDS diagnosis, type of mutation (as per Waespe et al., Genomic Medicine 2017). Univariate Cox Proportional Hazard modelling was used to estimate association with specific variables and disease progression, Kaplan-Meier analysis was used for survival evaluation. Results Between January 1, 2001 and November 30, 2018, 601 patients were enrolled in the CIMFR, and during this time 59 (9.8%) developed cytogenetic clones/MDS. Four did not meet the pre-defined criteria for IBMFS, 9 had RCEB at diagnosis with MDS and 1 did not have data available; these were excluded from our cohort of 45 patients. Twelve (26%) patients with clones/MDS had Fanconi Anemia (FA), 13 (28.3%) had Shwachman-Diamond Syndrome (SDS), 5 (10.8%) had ucIBMFS, 15 (33.3%) had other IBMFSs. The most common cytogenetic finding at diagnosis was -7/-7q (n=10, 22%). Patients who developed clones/MDS had significantly worse OS compared to those without clones/MDS (HR 3, 95% CI 2-6, p<0.0001). Among patients who developed clones/MDS, 22 (48.9%) underwent HSCT. Twenty one clones/MDS patients (46.7%) had disease progression, with a median time to progression of 7.9 months (1.2-131.4). The majority (68.4%) developed progression within one year of clones/MDS diagnosis. Nine (42.8%) developed more advanced cytopathology, 9 (42.8%) a new cytogenetic abnormality and 5 (23.8%) worsening cytopenias. Most patients with FA (67%) had disease progression, compared to 38.5% of patients with SDS. Mutation types (classified as more vs less deleterious) were similar between the groups with and without progression. The evaluated hematologic parameters (MCV, hemoglobin, platelets and neutrophils within 3 months of diagnosis) were not predictive of disease progression. Patients with disease progression, when compared to those without, were more likely to have congenital malformations of the skin (14.3% vs 0%), cardiovascular system (28.6% vs 4.2%) and kidneys (14.3% vs 4.2%). No specific system involvement predicted disease progression, although congenital malformations of the cardiovascular system had a HR of 2.63 (95% CI 0.93-7.42). Conclusion Development of MDS has a significant adverse impact on the OS of IBMFS patients, with disease progression typically occurring within the first year after MDS diagnosis. Patients with FA have a high risk of disease progression. Hematologic parameters were not predictive of the risk of disease progression, however, the presence of congenital cardiovascular anomalies is suggestive of increased risk of disease progression and warrants further investigation. Our study is limited by the rare nature of IBMFSs and MDS and the collection of additional data will help to guide treatment decisions for this high-risk patient population. Acknowledgment The authors thank Mr. Bryan Maguire for his statistical analysis of data related to this work.

Efficacy and Safety of IDH Inhibitors in AML: A Systematic Review of Clinical Trials

Background: Isocitrate dehydrogenase (IDH) gene mutation leads to the accumulation of oncometabolite. IDH 1 and 2 gene mutations are associated with multiple malignancies including gliomas, leukemias, etc. Despite improving treatment for hematological malignancies, advanced acute myeloid leukemia is associated with a poor prognosis. In this systematic review, we assessed the efficacy and safety of IDH 1 and 2 inhibitors used alone or in combination with other drugs in IDH 1 and 2 mutated AML. Methods: We followed PRISMA guidelines to conduct this systematic review. A literature search was performed on PubMed, Web of Science, and Embase (Ovid) with mesh terms, "Acute Myeloid Leukemia" and "Isocitrate dehydrogenase" from the inception of data till 6/15/2022. We screened 3,263 articles and included 3 randomized clinical trials (RCTs, N=398) and 4 non-randomized clinical trials (nRCTs, N=609) measuring the efficacy and safety of IDH inhibitors in AML. Results: In 7 clinical trials, 1,007 adult patients with IDH mutated AML were included. 472 patients had IDH-2 mutation (mIDH-2) while 535 patients had IDH-1 mutation (mIDH-1). 582 patients had relapsed/refractory (R/R) disease while 425 patients had newly diagnosed (ND) disease. In a clinical trial on R/R mIDH-2 AML patients treated with enasidenib (N=280), overall response rate (ORR), complete response (CR), morphologic free state (MLFS), and median overall survival (mOS) were 39.6%, 18.9%, 5.7%, and 8.8 months, respectively. In two clinical trials (N=192) on ND mIDH-2 AML patients, ORR was 74%-89%, CR was 54%-55%, and MLFS was 4%-11% with enasidenib + chemotherapy/azacytidine as compared to ORR of 36%, CR of 12%, and MLFS of 0% with azacytidine alone. However, the mOS was not significantly different among the two groups. Table 1. In two clinical trials (N=206) on ND mIDH-1 AML patients, ORR was 63%-87%, CR was 47%-68%, and MLFS was 7%-8% with ivosedanib + chemotherapy/azacytidine as compared to ORR of 19%, CR of 15%, and MLFS of 0% with azacytidine alone. The hazard ratio (HR) of OS was significantly in favor of ivosedanib + azacytidine as compared to azacytidine alone. In a clinical trial on R/R mIDH-1 AML patients treated with ivosedanib (N=179), ORR, CR, MLFS, and mOS were 39.1%, 21.8%, 5.6%, and 9.3 months, respectively. In two clinical trials, ORR with BAY1436032 (N=27) and olutasidenib (N=123) were 15% and 46% respectively. Table 1. ≥Grade 3 hyperbilirubinemia, thrombocytopenia, IDH differentiation syndrome, anemia, thrombocytopenia, neutropenia, diarrhea, and long QT syndrome were the common side effects reported in AML patients treated with IDH inhibitors. Table 1. Conclusion: IDH inhibitors were well tolerated by most of the patients with AML. Enasidenib significantly improved the response rates in patients with mIDH-2 AML. However, the OS was not improved with the addition of enasidenib in ND mIDH-2 AML patients in phase 2 RCT. Ivosedanib significantly improved the response rates and survival rates in patients with mIDH-1 AML. Olutasidenib was also effective in patients with R/R mIDH-1 AML. More randomized double-blind multicenter clinical trials are needed to confirm these results. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Novel Dual-Antigen Targeting Approach Enables Off-the-Shelf CAR NK Cells to Effectively Recognize and Eliminate the Heterogenous Population Associated with AML

While acute myeloid leukemia (AML) treatment has improved, relapse is still common, even after reduced intensity conditioning allogeneic transplantation. Natural killer (NK) cells are a promising allogeneic cell immunotherapy without the risk of graft-versus-host disease or cytokine release syndrome. We and others have reported that haploidentical NK cells can safely result in 30-50% complete remissions in advanced AML patients when given with high-dose lymphodepleting chemotherapy and exogenous cytokine support. However, while NK cell natural cytotoxicity has a clinical signal in AML, increased specificity and multi-dosing are likely to enhance the efficacy and durability of this treatment strategy. A number of stress ligands, including the MHC-I polypeptide-related sequence A and B (MICA/B), bind to the NK cell activating receptor NKG2D and initiate NK cell killing of transformed and infected cells, and several groups have shown promising results in clinical trials by developing NK cells that carry a NKG2D chimeric antigen receptor (CAR). However, the distal α1 and α2 domains of MICA/B that are recognized by NKG2D can be proteolytically cleaved from the surface of the tumor by metalloproteases, allowing for escape from NK cell-mediated detection and elimination. Wucherpfennig and colleagues have described that the membrane proximal α3 domain remains on the cell surface and may be a potential target for immunotherapy across many cancers, including AML. However, since AML is heterogenous, we hypothesized that clinical success would require dual-targeting and selected CD33 as the ideal complementary targeting approach since CD33 is a validated marker expressed on greater than 80% of AML blasts. To this end, our lab has developed a Tri-specific Killer Engager (TriKE) capable of agonistically ligating the CD16 Fc receptor to CD33 found on AML along with IL-15 co-stimulation to further activate the NK cell response. Here, we demonstrate the efficacy of a multiplexed-gene edited induced pluripotent stem-cell (iPSC) derived NK cell (iNK) product that expresses a high-affinity, non-cleavable version of CD16 (hnCD16), a membrane-bound IL-15 fusion receptor, CD38 knockout to enhance metabolic fitness, and a CAR against the α3 domain of MICA/B (α3 MICA/B) to drive a potent response against AML alone and when combined with anti-CD33 TriKE. In the initial study, the iNK cell backbone (iNK cells without the α3 MICA/B CAR) induced potent activity against the AML cell line HL60, and displayed further enhancement of activity with the addition of anti-CD33 TriKE (GTB-3650), representing combined effects of natural cytotoxicity and antibody-dependent cellular cytotoxicity. To show specificity for α3 MICA/B targeting, the AML cell line THP-1 was stained for the presence of MICA/B by flow cytometry using the 6D4 clone that recognizes the α1/2 domains of MICA/B or the 7C6 clone that uniquely recognizes the α3 domain +/- proteolytic cleavage with trypsin (Fig. 1A-B). Significant expression of the α3 domain was observed on THP-1 cells using the 7C6 antibody, which was highly expressed even after protease treatment. On the other hand, the α1/2 domains of MICA/B were detectable at lower levels using the 6D4 antibody and were undetectable after protease treatment (Fig. 1A-B). To assess a dual targeting approach, THP-1 cells were used as targets in live imaging functional assays under standard conditions (Effector:Target [E:T] 2:1). The iNK cell backbone had modest natural cytotoxicity at 3 hours that was significantly enhanced by the addition of α3 MICA/B CAR. The effect was further improved with more rapid killing kinetics when combined with the anti-CD33 TriKE (Fig. 1C). To evaluate the efficacy of dual-targeting in a more stringent physiologic manner, we mimicked "stress” conditions by minimizing the E:T ratio to 0.25:1. While all effector conditions induced immediate killing in 4 hours at the low E:T ratio, sustained tumor control was only observed with dual-antigen targeting (Fig. 1D). Studies with primary AML targets, +/- preincubation of decitabine and all-trans retinoic acid, known to upregulate NKG2D ligands in AML, are in progress and will be discussed. In summary, dual-targeting strategies using off-the-shelf CAR NK cells targeting α3 MICA/B in combination with antigen-specific TriKE targeting CD33 represent an ideal clinical strategy to enhance efficacy and durability of treatment in advanced AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Differential Impact on Survival in Myeloid Neoplasm Patients with U2AF1 Mutations

Introduction:U2AF1 mutations (m) are associated with abnormal splicing of genes involved in functionally important pathways, such as cell cycle progression and RNA processing. The U2AF1 gene has specific hotspots for mutations primarily involving the S34F and Q157P residues within the ZnF1 and ZnF2 causing mis-splicing of genes critical for hematopoiesis. Most recently in European Leukemia Net 2022 guidelines, U2AF1m is categorized as high-risk disease with inferior survival. We analyze outcome of U2AF1m in myeloid neoplasms and co-mutation patterns in large cohort of patients treated at Mayo Clinic. Methods: We reviewed our myeloid neoplasms patients (pts) database who underwent NGS (MC OncoHeme 42 genes panel) testing between October 2015 and August 2021. We identified 121 myeloid neoplasm pts with U2AF1m, and these were analyzed for clinical characteristics, co-mutational patterns, and outcomes using SPSS statistical software. An appropriate IRB approved was obtained. Results: The median age at diagnosis was 71 years (range [R], 19-92) (Table 1). Sixty-one (51%) pts were diagnosed with MDS, 29 (24%) pts with myeloproliferative neoplasms (MPN), 23 (19%) pts with acute myeloid leukemia (AML), 12 (10%) pts with MDS/MPN overlap and 3 (2.5%) pts with clonal cytopenia of unknown significance (CCUS). Out of 61 pts diagnosed with MDS, 59 pts had risk stratification information based on the revised international prognostic scoring system (IPSS-R): 20 (33.9%), 18 (30.5%), 17 (28.8%) and 4 (6.8%) patients were stratified into low, intermediate, high, and very high risk, respectively. Thirty-one out of 102 (30%) pts with MDS/MPN/MDS-MPN overlap progressed to AML with median time to AML progression 14.6 months (R, 1-118). Forty-four percent and 32% of pts had mutations involving the S34F and Q157P hotspots respectively, while the remaining had Q157R (12%), S34Y (6%), R156H (5%) and R35L (1%). The median variable allele frequency (VAF) was 38% (R, 2-49). Isolated U2AF1m was seen in 15 (12.4%) patients, 9 of these patients were diagnosed as MDS. The rest of the patients (87.6%) had at least 1 co-mutation, the most common ones being ASLX1 (46%), JAK2 (19%), TET2 (17.5%), RUNX1 (14%), DNMT3A (14%) and BCOR (14%). We did sub-group analysis for overall survival (OS) in advanced MDS and AML patients harboring most frequent U2AF1 mutations (S34F, Q157P and Q157R). The mOS was 31.3, 20.5 and 8.8 months (mo) in MDS/AML pts with S34F, Q157P and Q157R mutations, respectively (p= 0.005, Figure 1A). While VAF <40% (OS 21.5 mo) vs VAF >40% (OS 24.5 mo) had no differential impact on OS (p= 0.98, Figure 1B). Conclusion: In this study, we have demonstrated that U2AF1 gene with S34F hotspot have better OS, while Q157R had significantly inferior OS in pts with MDS/AML. Contrary to earlier reports we did not observe significant survival difference in MDS/AML patients with VAF cutoff of 40%. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

59 (PB049) - PIN-A1, a novel Casein Kinase 1α-selective molecular glue degrader, demonstrates strong antitumor activity via activation of the p53 pathway in preclinical models of AML with a favorable safety profile

Casein kinase 1α (CK1α) reportedly promotes tumor growth by increasing the negative effects of MDM2 and MDMX on p53. Unlike in many other cancer types, the frequency of TP53 mutations is relatively low (<20%) in acute myeloid leukemia (AML). Therefore, activating the p53 pathway has been considered an attractive strategy to treat the disease with wild-type (WT) TP53. However, promising preclinical activities of p53 activators represented by MDM2 inhibitors have not been fully translated into clinical efficacy, partly due to their on-target hematological toxicities. To develop a drug targeting CK1α, we screened a series of compounds hijacking cereblon (CRBN) E3 ligase and identified a novel CK1α-selective molecular glue degrader (MGD), PIN-A1. Here, we report its robust pharmacological activities in various preclinical models of AML and its superior safety profile to MDM2 inhibitors. First, PIN-A1’s activity against CK1α as a MGD was demonstrated by the formation of ternary complex of PIN-A1-CK1α-CRBN using TR-FRET assay and with the inhibitors of proteasome/neddylation, respectively. Selective degradation of CK1α by PIN-A1 was also confirmed by global proteomics analysis. As predicted, PIN-A1 induced rapid degradation of CK1α protein in human AML MV-4–11 cells with WT TP53, which was followed by increases in the levels of p53 protein and its downstream target genes, ultimately leading to apoptotic cell death. Consistent with these results, screening in a broad panel of liquid cancer cell lines demonstrated preferential sensitivity of AML cells with WT TP53 to the CK1α degrader. When combined with cytarabine or other targeted therapies in AML such as venetoclax (Bcl2i), AMG232 (MDM2i), or gilteritinib (FLT3i), PIN-A1 displayed strong synergistic effects in cell killing. To evaluate its pharmacological activity in vivo, PIN-A1 was tested in a s.c xenograft model of MV-4-11 and a dissemination model of MOLM-14, respectively. Systemic administration of PIN-A1 alone via i.p resulted in robust antitumor activity with >90% CK1α degradation in tumors, which was comparably achieved at a much lower dose in combo treatments. Importantly, animals remained tumor-free (5/8) in the MV-4-11 model or survived longer in the MOLM-14 model even after they were off the combination treatment of PIN-A1 with AMG232. Lastly, while PIN-A1 had minimal effects on the viability and the p53 pathway in human PBMC at efficacious doses for MV-4-11 (Therapeutic index [TI] = >8000) despite >90% CK1α degradation, AMG232 induced the p53 pathway and reduced viability to a similar extent in both cell types (TI = 4). Taken together, these results suggest that a CK1α MGD with its favorable safety profile has a potential to become an effective treatment option for advanced AML. Current activities are focused on more advanced MGD analogs with superior oral systemic exposure. No conflict of interest.

BTX-1188, a first-in-class dual degrader of GSPT1 and IKZF1/3, for treatment of acute myeloid leukemia (AML) and solid tumors.

7025 Background: BTX-1188 is a first-in-class oral molecular glue that degrades GSPT1 and IKZF1/3 and is currently in phase 1 clinical trials for treatment of hematologic and solid malignancies. Targeted protein degradation of cereblon neosubstrates is clinically validated in the treatment (tx) of hematologic malignancies (Lu 2014, Zou 2020). Methods: Cell viability in BTX-1188-treated cells and patient samples was measured by CellTiter-Glo 2.0 assay (Promega). Substrate degradation and apoptosis profiles were analyzed by immunoblots of protein lysates from cells treated with DMSO or BTX-1188. Vehicle, or 30 or 40 mg/kg IP BTX-1188, was used in athymic nude mice AML xenograft models. Results: BTX-1188 is a rapid, deep, and potent degrader of GSPT1 and IKZF1/3 and inhibitor of Myc in several cancer cell lines (Table). Proteomics and immunoblot analysis of AML cell line, MV-4-11, shows significant degradation of GSPT1 and IKZF1 after 2 h tx with 100 nM BTX-1188 ( P&lt;1x10-5) and 6 h tx with 3 nM BTX-1188 (&gt;90% of GSPT1), respectively, indicating rapid and potent neosubstrate degradation. BTX-1188 also durably degrades GSPT1 where tx with 30 nM for 6 h followed by washout maintains significantly lower levels of GSPT1 and sustained apoptosis for up to 24 h. Owing to IKZF1/3 degradation, BTX-1188 has immunomodulatory properties as seen by inhibition of proinflammatory cytokines (IL-1β, IL-6, TNFα) and induction of IL-2 by LPS and αCD3-stimulated PBMCs, respectively. This approach is expected to improve clinical outcomes and reduce toxicities associated with pure GSPT1 degradation (CC-90009), thus expanding the therapeutic window of BTX-1188. Functionally, BTX-1188 is cytotoxic in various cancer cell lines such as Myc-driven lines (IC50 range: 0.5-10 nM) and primary human AML patient samples (IC50 range: 0.4-1.5 nM), including relapsed/refractory-, cytarabine- and venetoclax-resistant samples. The durability of GSPT1 degradation and sustained apoptosis in response to BTX-1188 tx is further reflected in in vivo efficacy models where daily or intermittent dosing of BTX-1188 results in potent and sustained antitumor activity. Conclusions: These preclinical data show that BTX-1188 is a promising drug candidate for AML and other tumor types. Its immunomodulatory properties owing to IKZF1/3 degradation may prevent systemic inflammatory dose-limiting toxicities associated with pure GSPT1 degradation (Uy 2019). BTX-1188 has entered phase 1 clinical studies for advanced solid tumors and AML. DC50 (nM) or inhibitory concentration (nM) of BTX-1188 at 6 h of Tx. [Table: see text]

A multicenter, open-label, phase I/II study of FN-1501 in patients with advanced solid tumors and acute myeloid leukemia.

e15083 Background: FN-1501, a potent inhibitor of receptor FMS-like tyrosine kinase 3 (FLT3) and CDK4/6, KIT, PDGFR, VEGFR2, ALK and RET tyrosine kinase proteins, has demonstrated significant in vivo anti-tumor activity in a broad range of solid tumor and leukemia xenograft models. FLT3 mutations have an established role as a therapeutic target in Acute Myeloid Leukemia (AML), where the gene plays a critical role in the growth, differentiation, and survival of hematopoietic cells. An open-label, Phase I/II study ( NCT03690154 ) is evaluating the safety and PK profile of FN-1501 as monotherapy in patients (pts) with advanced solid tumors and relapsed, refractory (R/R) AML. Methods: Pts received FN-1501 IV thrice weekly for 2 weeks followed by 1 week off treatment in 21-day cycles. Dose escalation follows a 3+3 design. Primary objectives include determination of maximum tolerated dose (MTD), safety, and recommended phase 2 dose (RP2D). Secondary objectives include pharmacokinetics (PK) and preliminary anti-tumor activity. Exploratory objectives include the relationship between pharmacogenetic mutations (e.g., FLT3, TP53, KRAS, NRAS), safety, efficacy and pharmacodynamic effects of FN-1501. Dose expansion at RP2D was designed to further explore safety and efficacy. Results: As of Dec 3, 2021 data cut-off (DCO), 47 pts with advanced solid tumors (N = 46) or AML (N = 1) were enrolled at doses ranging from 2.5 to 226 mg. The median age was 65 (range 30-92) with 57% female and 43% male. The median prior lines of treatment were 5 (range 1-12). Forty pts with median exposure of 9.5 cycles (range 1-18 cycles) were evaluable for dose limiting toxicity (DLT). Treatment-related adverse events (TRAEs) were reported in 64% of pts. The most common treatment-emergent adverse events (TEAEs) defined as those occurring in ≥ 20% of patients primarily consisted of reversible grade 1-2 fatigue (34%), nausea (32%) and diarrhea (26%). The most common grade ≥ 3 events occurring in ≥ 5% of pts consisted of diarrhea and hyponatremia. Dose escalation was discontinued due to DLTs of grade 3 thrombocytopenia (N = 1) and grade 3 infusion related reaction (N = 1) in 2 pts in the 226 mg dose group (2nd DLT reported after DCO). At the time of DCO, 33 pts were evaluable for disease response showing 1 with partial response (PR) (47% target lesion shrinkage), 15 with stable disease (SD) and 17 with progression of disease (PD). The PR lasted &gt; 4 months (mts) in a patient with endometrial carcinoma (ca) at the 40 mg dose level. The longest treatment exposures were recorded in 6 pts with SD of 2.6 to &gt; 12 mts (thymoma [1]; ovarian ca [2]; renal cell ca [1]; laryngeal ca [1] and intestinal adeno ca [1]) at doses ranging from 15 mg to 170 mg. Conclusions: FN-1501 IV has shown reasonable safety, tolerability, and preliminary activity against solid tumors up to 170 mg. Dose escalation was terminated based on 2 DLTs occurring at the 226 mg dose level. Clinical trial information: NCT03690154.

Eradication of leukemia stem cells by inhibitors of DNA methyltransferase, EZH2 and G9a histone methyltransferases

Complete eradication of leukemic stem cells (LSCs) in patients with acute myeloid leukemia (AML) is required for curative therapy. Epigenetic alterations that involve gene-silencing by DNA methylation by DNMT1, methylation of H3K27 by EZH2 histone methyltransferase (HMT) and methylation of H3K9 by G9a HMT may play a major role in the development of AML. The major action of these epigenetic alterations is the silencing of the genes that program differentiation of AML cells. Inhibitors of DNA and histone methylation have the potential to reverse this block in differentiation. If tumor suppressor genes (TSGs) contain two gene-silencing markers, such as DNA methylation and H3K27me3, they may not be fully reactivated with only an inhibitor of DNA methylation, such as 5-aza-2’-deoxycytidine (5-AZA-CdR), but may also require an inhibitor of EZH2. In support of this model is the synergistic antileukemic action as shown by a colony assay on AML cells using 5-AZA-CdR in combination with 3-deazaneplanocin A (DZNep), a potent inhibitor of EZH2. A similar type of interaction can occur when TSGs are silenced by DNA methylation and the G9a methylation of H3K9me2, a second gene-silencing marker. Treatment of these AML cells with 5-AZA-CdR and BIX01294, an inhibitor of G9a, also results in a synergistic antileukemic action. Leukemic cells that contain 3 different gene-silencing markers: DNA methylation, H3K27me3 and H3K9me2 may require 3 different inhibitors for maximal antineoplastic activity. This result was observed when the AML cells were treated in with 5-AZA-CdR, DZNep and BIX01294. The aim of this study was to demonstrate that epigenetic agents that target DNA and histone methylation have remarkable antineoplastic activity against myeloid leukemia cells. The second aim was to propose a dose-schedule for these epigenetic agents that can be evaluated in a clinical trial in patients with advanced AML for its potential to eradicate LSCs. One of the most sensitive targets for chemotherapeutic intervention in LSCs is the block in differentiation due to gene-silencing by DNA and histone methylation. Epigenetic agents that have the potential to reverse this block merit clinical investigation with high priority.

Implementation of Inpatient Palliative Care Consultation Triggers and Its Impact on Healthcare Use in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Background: Patients with relapsed/refractory acute myeloid leukemia (AML) have poor outcomes and high levels of healthcare utilization at end of life. Palliative care remains underused in this population despite the high symptom burden. Questions remain regarding how best to integrate palliative care for high risk hematology patients. Prior implementation of standardized palliative care consultation triggers on an inpatient solid tumor service led to increased palliative care consultations and decreased healthcare utilization (Adelson et al, JOP 2017). We conducted a prospective cohort study evaluating standardized palliative care consultation triggers for patients admitted to a tertiary academic center with advanced AML.Method: Trigger criteria were developed for hospitalized patients with hematologic malignancies on the inpatient hematology floors at Smilow Cancer Hospital and included: 1) persistent disease after ≥ 2 lines of therapy, 2) length of stay (LOS) >7 days for symptom management, 3) Eastern Cooperative Oncology Group (ECOG) performance status > 2, and 4) refractory graft versus host disease (GVHD) after ≥ 3 lines of therapy. Patients with relapsed/refractory AML were included if they met criteria #1. A palliative care nurse coordinator performed chart review of admitted patients 1-2 times per week from June to December 2020 and contacted the primary team when a patient met eligibility. Patient characteristics and healthcare outcomes were compared with patients with AML meeting criteria #1 admitted pre-intervention (June to December 2019) using Fisher t-tests.Results: A total of 110 admitted patients with advanced AML met eligibility criteria #1 (64 pre-intervention and 46 post-intervention). Baseline patient and disease characteristics were similar, including mean age at admission (60.4 vs 60.9 years, p=0.848), gender (64% vs 59% male, p=0.691), prior transplant (56% vs 52%, p=0.702), and AML risk stratification (67% vs 78% adverse risk, p=0.283). In the post-intervention group, 61% of eligible patients were screened. Of the screened patients, 54% received a palliative care consult, 18% were declined by the primary team, 14% were marked as not eligible, and 14% did not have a palliative care consult with reason unspecified. Within the same admission, there was a significant increase in advance care planning and/or advanced directive documentation post-intervention (13% vs 28%, p=0.049). There was no differences in pre- and post-intervention groups in time to palliative care consult from admission (7.2 vs 4.9 days, p=0.245), LOS (12.13 vs 12.33 days, p=0.941), 30-day readmissions (52% vs 39%, p=0.246), critical/intermediate care escalation (22% vs 13%, p=0.318) during the same admission.By July 2021, 92% of the pre-intervention patients and 57% of the post-intervention patients were deceased. Of the deceased patients, there was no differences in pre- and post-intervention groups in blood transfusions (100% vs 96%, p=0.306) or hospice enrollment (46% vs 62%, p=0.157) within 14 days of death. There was also no significant differences in pre- and post-intervention groups in non-palliative anti-neoplastic therapy use (37% vs 38%, p=0.999), hospital admissions (95% vs 88% p=0.364), or critical/intermediate care escalation (51% vs 38%, p=0.350) within 30 days of death.Conclusion: A trigger-based palliative care referral intervention is feasible and doubled palliative care use in patients with relapsed/refractory AML. Our intervention was associated with increased advance care planning documentation during the admission. There were directional changes in other healthcare measures, including decreased time to palliative care consult and escalation of care, as well as increased hospice enrollment. These differences, however, were not statistically significant due to the small sample size. The significant healthcare use likely reflected high symptom burden at end of life, associated with transfusions and admissions for infection and symptom management. More research is needed to determine how best to support these patients at end of life. Of note, our intervention period occurred during the COVID-19 pandemic, which may have impacted threshold for inpatient admissions and the inpatient census. DisclosuresAdelson: Carrum Health: Other: Stock; Abbvie: Consultancy; Roche/Genentech: Consultancy, Honoraria, Patents & Royalties, Research Funding; Heron: Consultancy; Celgene: Consultancy. Prebet: BMS: Research Funding; BMS, Curios, Daichi: Consultancy.

WT1 and DNMT3A Play an Essential Function and Represent Therapeutic Vulnerabilities in Certain AML Samples, As Shown By CRISPR/Cas9 Mediated Knockout in PDX Models In Vivo

Background:The prognosis of patients with acute myeloid leukemia (AML) remains poor and novel therapeutic options are intensively needed. Targeted therapies specifically address molecules with essential function for AML and deciphering novel essential target genes is of utmost importance. Functional genomics via CRISPR\\Cas9 technology paves the way for the systematic discovery of novel essential genes, but was so far mostly restricted to studying cell lines in vitro, lacking features of, e.g., primary tumor cells and the in vivo tumor microenvironment. To move closer to the clinical situation in patients, we used the CRISPR\\Cas9 technology in patient-derived xenograft (PDX) models of AML in vivo.Methods:Primary tumor cells from seven patients with AML were transplanted into immunocompromised NSG mice and serially transplantable PDX models derived thereof. PDX models were selected which carry the AML specific mutations of interest at variant allele frequencies close to 0.5. PDX cells were lentivirally transduced to express the Cas9 protein and a sgRNA; successfully transduced PDX cells were enriched by flow cytometry gating on a recombinant fluorochrome or by puromycin. The customized sgRNA library was designed using the CLUE (www.crispr-clue.de) platform and cloned into a lentiviral vector with five different sgRNAs per target gene, plus positive and negative controls (Becker et al., Nucleic Acids Res. 2020). PDX cells were lentivirally transduced with the CRISPR/Cas9 sgRNA library, transplanted into NSG mice, grown in vivo and cells re-isolated at advanced AML disease. sgRNA distribution was measured by next generation sequencing and compared to input control using the MAGeCK pipeline.Interesting dropout hits from PDX in vivo screens were validated by fluorochrome-guided competitive in vivo experiments in the PDX models, comparing growth of PDX AML cells with knockout of the gene of interest versus control knockout in the same mouse. PDX cells were transduced with lentiviral vectors expressing a single sgRNA, using in parallel three different sgRNAs per target gene. Targeting and control sgRNAs were marked by different fluorochromes; PDX cells expressing targeting or control sgRNA were mixed at a 1:1 ratio, injected into NSG mice and PDX models competitively grown until advanced disease stage, when cell distributions was determined by flow cytometry.Human AML cell lines were studied in vitro for comparison.Results:In search for genes with essential function in AML, we cloned a small customized sgRNA library targeting 34 genes recurrently mutated in AML and tested the library in two PDX AML models in vivo. From the dropouts, we validated most interesting target genes using fluorochrome-guided competitive in vivo assays.Knockout of NPM1 abrogated in vivo growth in all PDX AML models tested, reproducing the known common essential function of NPM1. KRAS proved an essential function in PDX AML models both with and without an oncogenic mutation in KRAS, although with a stronger effect upon KRAS mutation, suggesting that patients with tumors both with and without KRAS mutation might benefit from treatment inhibiting KRAS.Surprising results were obtained for WT1 and DNMT3A. Both genes are frequently mutated in AML, but most AML cell lines tested in vitro do not show an essential function of any of the two genes, in published knockdown or knockout data, including from the Cancer Dependency Map database. On the contrary, knockout of either WT1 or DNMT3A was shown to enhance growth of AML cell lines and increase leukemogenesis in certain models.In PDX models in vivo, we found a clearly essential function for DNMT3A in all AML samples and WT1 in most samples tested and PDX in vivo results were discordant to cell line in vitro data, suggesting that cell line inherent features and/or the in vivo environment influence the function of WT1 and DNMT3A.Conclusion:We conclude that functional genomics in PDX models in vivo allows discovering essentialities hidden for cell line in vitro approaches. WT1 and DNMT3A harbor the potential to represent attractive therapeutic targets in AML under in vivo conditions, warranting further evaluation. DisclosuresNo relevant conflicts of interest to declare.

Impact of CMV reactivation on relapse of acute myeloid leukemia after HCT is dependent on disease stage and ATG

AbstractCytomegalovirus (CMV) reactivation is a frequent complication after allogeneic hematopoietic cell transplantation (HCT), whose impact on clinical outcome, in particular on leukemic relapse, is controversial. We retrospectively analyzed 687 HCT recipients with acute myeloid leukemia (AML) and ciclosporin-based immunosuppression to better understand the differential impact of CMV on transplant outcomes depending on AML disease stage and in vivo T cell depletion with antithymocyte globulin (ATG). Without ATG, CMV reactivation associated with significantly reduced relapse, yet its effect was more pronounced for advanced disease AML (P = .0002) than for patients in first complete remission (CR1, P = .0169). Depending on the disease stage, ATG exposure abrogated relapse protection following CMV reactivation in advanced stages (P = .796), while it inverted its effect into increased relapse for CR1 patients (P = .0428). CMV reactivation was associated with significantly increased nonrelapse mortality in CR1 patients without ATG (P = .0187) but not in those with advanced disease and ATG. Following CMV reactivation, only patients with advanced disease had significantly higher event-free survival rates as compared with patients without CMV. Overall, our data suggest that both ATG and disease stage modulate the impact of post-HCT CMV reactivation in opposite directions, revealing a level of complexity that warrants future studies regarding the interplay between antivirus and antitumor immunity.

Impact of an automatic palliative care consultation trigger on healthcare use in patients with relapsed/refractory acute myeloid leukemia.

224 Background: Patients with relapsed/refractory acute myeloid leukemia (AML) have poor outcomes and high levels of healthcare use at end of life. Palliative care remains underused in hematology and questions remain on how best to integrate palliative care for high-risk patients. We conducted a prospective cohort study evaluating palliative care consultation triggers for patients admitted to a tertiary academic center with advanced AML. Methods: Criteria were developed for all hospitalized patients with hematologic malignancy on the inpatient hematology floors and included: 1) persistent disease after ≥ 2 lines of therapy, 2) length of stay (LOS) &gt; 7 days for symptom management, 3) ECOG performance status &gt; 2, and 4) refractory GVHD ≥ 3 lines of therapy. Patients with relapsed/refractory AML were included if they met criteria 1. A nurse coordinator performed chart review of admitted patients 1-2 times/week from June to December 2020 on the inpatient hematology floor at Smilow Cancer Hospital and contacted the primary team when patients met eligibility. Patient characteristics and healthcare outcomes were compared with patients with AML meeting criteria 1 admitted pre-intervention (June to December 2019) using Fisher t-tests. Results: A total 110 admitted patients were eligible (64 pre-intervention and 46 post-intervention). Baseline patient and disease characteristics were similar, including mean age at admission (60.4 vs 60.9 years, p = 0.848), gender (64% vs 59% male, p = 0.691), prior transplant (56% vs 52%, p = 0.702), and AML risk stratification (67% vs 78% adverse risk, p = 0.283). In the post-intervention group, 61% of eligible patients were screened. Of the screened patients, 54% received a palliative care consult, 18% were declined by the primary team, 14% were marked as not eligible, and 14% did not have consult with reason unspecified. Overall, palliative care consults increased in the post-intervention group (22% vs 43%, p = 0.021). There was a significant increase in advance care planning and/or advanced directive documentation post-intervention (13% vs 28%, p = 0.049). There was no differences in pre- and post-intervention groups in LOS (12.13 vs 12.33 days, p = 0.941), 30-day readmissions (52% vs 39%, p = 0.557), critical/intermediate care escalation (22% vs 13%, p = 0.318) and non-palliative chemotherapy post-discharge (48% vs 39%, p = 0.246). Conclusions: A triggered palliative care referral intervention is feasible and doubled palliative care use in patients with relapsed/refractory AML, a group with high mortality and high healthcare utilization. Our intervention improved documentation of advance care planning. Although there were directional reductions in other healthcare use measures, the differences were not statistically significant, likely from the small sample sizes leading to the study being underpowered.

Abstract CT131: A Phase I safety and tolerance study of FN-1501, a novel FLT3 inhibitor, in patients with advanced solid tumors and acute myeloid leukemia

Abstract Background: FLT3 mutations are found in approximately 30% of adult patients with Acute Myeloid Leukemia (AML) and to a lesser degree, in certain solid tumors. FN-1501 is a potent inhibitor of FLT3 and other tyrosine kinases such as CDK4/6, KIT, PDGFR, ALK and RET proteins, with demonstrated anti-tumor activity in several leukemia and colon cancer xenograft models. An ongoing, open-label, Phase I study (NCT03690154) is evaluating FN-1501 as monotherapy in patients with various advanced solid tumors and relapsed, refractory (R/R) AML. The objectives of the trial are to assess safety and tolerability, establish a Recommended Phase 2 Dose (RP2D), and evaluate preliminary anti-tumor activity. Methods: Pts received FN-1501 by IV thrice weekly for 2 weeks followed by 1 week off treatment in 21-day cycles. The dose escalation phase follows a standard 3+3 design. Primary objectives include determinations of dose-limiting toxicity (DLT), maximum tolerated dose (MTD), safety, and RP2D. Secondary objectives include pharmacokinetics (PK) and anti-tumor activity. Exploratory objectives include the relationship between pharmacogenetic mutations (e.g. FLT3, TP53, KRAS, NRAS, etc) and safety/efficacy. Expansion cohorts have been added to the ongoing protocol amendment to confirm safety and evaluate preliminary efficacy at RP2D. Results: At the time of data cut-off (Nov 17, 2020), 40 pts (n=1 AML; n=39 solid tumors) were enrolled at doses ranging from 2.5 to 128 mg. Median number of prior lines of treatment was 5 (range 1-12). Thirty-four patients met the minimum exposure criterion for DLT assessment. No DLTs were reported and MTD was not reached. Treatment-related adverse events (TRAEs) were reported in 58% of pts. The most common TRAEs in ≥10% of patients included fatigue (20%), nausea (15%), infusion related reaction (10%), mostly reversible grade 1 or 2. Grade ≥3 TRAEs consisting of anemia, fatigue and serum creatinine increase were observed in 3 pts. TRAEs resulted in dose delay/interruption in 4 pts (10%) but no treatment discontinuations. No serious TRAEs were observed. The exposure of FN-1501 (AUC and Cmax) increased in a dose proportional manner. Mean t1/2 was estimated to be 12-19 hours. Among 25 response-reportable pts, 1 had a best overall response of PR (47% target lesion shrinkage), 10 had stable disease and 14 had progressive disease. The confirmed PR (duration &amp;gt; 4 months) occurred at the 40 mg dose level in a pt with endometrial carcinoma. Conclusion: FN-1501 has demonstrated reasonable safety/tolerability across all doses tested, with promising anti-tumor activity in pts with certain advanced, heavily pre-treated solid tumors. Enrollment of pts into the dose escalation part of the study is continuing and updated safety, PK and molecular biomarker results will be presented at the meeting. Citation Format: Gary Edward Richardson, Stephen K. Williamson, Misako Nagasaka, Viviana Bozon, Maria Margarita Corvez, Chao Li, Wei Li, Jiao Wei, Ai-Min Hui. A Phase I safety and tolerance study of FN-1501, a novel FLT3 inhibitor, in patients with advanced solid tumors and acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT131.

Pre-Transplant Minimal Residual Disease Evaluation Performed By Molecular WT1-Based or Multicolor Flow Cytometry Assessment Overcomes the Prognostic Value of Cytogenetic and Molecular Risk Factors at Diagnosis in Advanced Acute Myeloid Leukemia Patients

BACKGROUND AND AIMSAllogeneic stem cell transplantation (HSCT) offers the only chance of cure for patients with advanced acute myeloid leukemia (AML). High levels of pre-HSCT minimal residual disease (MRD) have been reported to predict relapse risk after HSCT even in patient transplanted in first complete remission (CR). WT1 expression levels and multicolor flow cytometry (MFC) are the most common tools to evaluate MRD. The aim of this study was to analyze the role of pre-HSCT combined MRD assessment as predictor for the post-transplant relapse risk in patient transplanted beyond first CR.MATERIALS AND METHODSWe retrospectively analyzed the outcome of 92 consecutive AML patients receiving HSCT in 2nd or 3rd CR. Pre-HSCT marrow samples were analyzed for WT1 expression and MFC as MRD evaluation. Median age at transplant was 45 years. Disease phase was CR2 in 63 (68%) and CR3 in 29 patients (32%). ELN risk category at diagnosis was low in 28 (30%), intermediate in 44 (48%) and high in 20 (22%) patients. Sixty-six (71%) patients received myeloablative conditioning, whereas 26 patients (29%) received reduced intensity conditioning. Stem cell source was bone marrow in most cases and donor was an HLA-identical sibling in 18 (20%), haploidentical sibling (HAPLO) in 24 (26%) and unrelated donor in 50 (54%). Median follow-up was 64 months (95% CI 39.8 - 88.2 months).A positive MFC MRD was defined by the presence of at least 1x10-3 residual leukemic cells by 4 or 8 (since 2011) color flow-cytometry. WT1 copy number/Abl copy number 250x104 was used as cut-off value for abnormal WT1 expression.RESULTSRelapse occurred in 30 patients (33%) and two years non-relapse mortality was 29%. Three-year estimate of OS was 47.9% (median 19 months). The survival probability was significantly affected by donor source (better for HAPLO, p<0.05), ELN risk at diagnosis (better for ELN low risk, p<0.01), MRD status before HSCT measured with any method (p <0.01 for WT1-based MRD, p<0.03 for MFC based MRD) and CR status at HSCT (better for CR2, p<0.05).Specifically, among MRD negative patient a relatively low rate of relapse was observed regardless of risk at diagnosis (2-years OS of 62.2% and 52.7% among MFC MRD negative patient with ELN risk low or intermediate/high, respectively, Fig.1).The predictive value of MRD resulted independent from all other analyzed variables. However, patients with positive MRD did slightly better when undergoing HAPLO HSCT. Multivariate OS analysis revealed that the MRD evaluation by any method was the only independent predictor of OS (p <0.05 for both methods of analysis).MRD evaluation was also a strong predictor of cumulative incidence (CI) of relapse in competitive risk analysis (p<0.01 and p<0.03, respectively, for WT1 and MFC MRD). Multivariate CI of relapse analysis showed that donor source and MRD evaluation significantly influenced relapse risk (p <0.05 and <0.01, respectively).CONCLUSIONSPre transplant MRD evaluation by both WT1 and MFCon bone marrow samples is a reliable predictor of relapse risk which may overcome the prediction based on ELN risk at diagnosis. Both methods were able to efficiently predict post-transplant disease reoccurrence risk: patients with negative pre-HSCT MRD markers have a significantly better OS, while patients with positive MRD markers show an higher risk of relapse, irrespective of lower or higher ELN risk at diagnosis.Furthermore, our results seem to suggest that HAPLO donor may have a positive impact in reducing relapse rate in advanced AML patients, in particular in patients with positive MRD.Refining the baseline risk assessment based on ELN risk in patient undergoing HSCT beyond CR1 who have an higher risk of relapse is very important when evaluating optimal stem cell source and conditioning intensity and could allow to apply pre-emptive therapeutic strategies to prevent AML relapse, from donor lymphocyte infusion to other innovative approaches. [Display omitted] DisclosuresAngelucci:Roche: Other: Advisory board: biosimilars; Novartis Oncology: Other: Protocol Telesto: sterring committee Chair; Bluebird Bio: Other: Advisory board: Gene therapy in Thalassemia; Jazz: Other: Advisory board: AML; Celgene: Other: protocoll ACE 536 B-Thal 001: DMC Chair; Novartis Oncology: Other: Advisory board: iron toxicity; Novartis Oncology Swiss: Other: Invited speakers sponsored satellite meeting during ; Celgene: Honoraria, Other: Advisory: research project .

Anti-CD45 Radioimmunotherapy Followed By Haploidentical Allogeneic Hematopoietic Cell Transplantation for Advanced Acute Leukemia or High-Risk MDS

Background: Although hematopoietic cell transplantation (HCT) may offer the best chance for cure for patients with relapsed/refractory hematologic malignancies, many of these patients will relapse after HCT. Escalating doses of total body irradiation (TBI) or chemotherapy prior to HCT can decrease relapse, but incurs higher toxicity, resulting in no survival benefit. Therefore, there is a need to reduce relapse without increasing the toxicity of the conditioning regimen prior to HCT. In addition, many potentially curable candidates for HCT do not have a fully human leukocyte antigen (HLA) matched donor. This is an especially challenging hurdle for many ethnic minority patients, yet nearly all patients have a related donor identical for one HLA haplotype (i.e., haploidentical). Radioiodinated anti-CD45 radioimmunotherapy (RIT) has been shown to deliver high-doses of radiation specifically to hematolymphoid organs, while sparing normal tissues. We report a phase I/II study using iodine-131 (131I)-anti-CD45 antibody (BC8) combined with pre- and post-transplant cyclophosphamide, and reduced intensity conditioning prior to haploidentical HCT.Methods and Patients: Eligible patients over the age of 18 had relapsed or refractory acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), or high-risk (>5% active marrow blasts) myelodysplastic syndrome (MDS). Patients received a 131I-anti-CD45 dosimetry dose, followed by serial gamma-camera imaging for organ dosimetry estimates. One to two weeks later a therapeutic dose delivering escalating doses (12 to 26 Gy) to the liver (the normal organ that received the highest dose) was administered, followed by fludarabine (FLU; 30 mg/m2 on day -6 to -2), cyclophosphamide (CY; 14.5 mg/m2 on day -6 and -5), 200 cGy TBI on day -1, and subsequent haploidentical marrow HCT on day 0. For GVHD prophylaxis, patients received CY (50 mg/kg) on day+3 plus standard tacrolimus and mycophenolate mofetil.Results: A total of 25 patients have been treated (21 with advanced AML, 3 with ALL and 1 with high-risk MDS). Ten patients were in florid refractory relapse with 6-20% abnormal marrow blasts while 9 were in remission with minimal residual disease (MRD) 0.03-5.4% by flow cytometry, and only 6 were in remission and MRD negative by flow cytometry. All 24 patients who had marrow aspiration on day 28 after HCT achieved a morphologic remission, with only two patients showing MRD by flow cytometry (0.002 -1.8% abnormal blasts). There were no graft failures, and all patients with chimerism studies (n=15) had 100% donor CD3+ and CD33+ cell engraftment at day 28 after haploidentical HCT. Median time to neutrophil engraftment (ANC>500/ml for 3 consecutive days) was 15 (range, 12-19) days. Median time to platelet engraftment (platelets >20,000/ml for 7 consecutive days without transfusion support) was 23 (19-44) days. The maximum tolerated dose was not determined and there were no unexpected adverse events, as the most frequent grade ≥3 adverse events were infections/neutropenic fevers (32), gastrointestinal (22), and laboratory abnormalities (cytopenias 18; metabolic 16). Five patients had grades 3-4 acute GVHD. Twelve patients relapsed with median time to relapse of 2.4 months. Most deaths have been from relapse (11), and infections (2). Eight (32%) patients were alive at a median follow up of 4 years after HCT (range 1 to 9 years). Overall survival at one and three year was 42% and 26%, and progression-free survival was 40% and 25%, respectively (Figure).Conclusions: Although patients with active disease are not traditionally referred for HCT, the use of 131I-anti-CD45 RIT prior to a haploidentical HCT may facilitate improved survival for these patients. Given these results, anti-CD45 RIT prior to HCT using haploidentical donors warrants further investigation for patients with advanced leukemia and high-risk MDS. [Display omitted] DisclosuresOrozco:Actinium Pharmaceuticals: Other: Research Funding to Institution for sponsored Clinical Trials. Shadman:PLEXXIKON: Research Funding; AbbVie: Other: advisory board; Genentech: Consultancy, Research Funding; Emergent: Research Funding; TG Therapeutics: Research Funding; Gilead: Research Funding; Acerta Pharma: Research Funding; Celgene: Research Funding; Pharmacyclics: Other: advisory board, Research Funding; Merck: Research Funding. Gopal:Seattle Genetics: Consultancy, Research Funding. Pagel:Actinium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

A Phase Ib Study to Assess the Safety and Tolerability of Ruxolitinib in Combination with Azacitidine in Patients with Advanced Phase Myeloproliferative Neoplasms (MPN), Including Myelodysplastic Syndromes (MDS) or Acute Myeloid Leukaemia (AML) Arising from MPN (The Bloodwise / TAP PHAZAR Study on Behalf of the UK MPN CSG)

A Phase Ib Study to Assess the Safety and Tolerability of Ruxolitinib in Combination with Azacitidine in Patients with Advanced Phase Myeloproliferative Neoplasms (MPN), Including Myelodysplastic Syndromes (MDS) or Acute Myeloid Leukaemia (AML) Arising from MPN (The Bloodwise / TAP PHAZAR Study on Behalf of the UK MPN CSG)

MDS and AML in Shwachman-Diamond Syndrome: Clinical Features and Outcomes

Genetic predisposition to MDS and AML is recognized in a growing subset of patients, but data to inform medical management and outcomes are sparse. Shwachman-Diamond syndrome (SDS) is an inherited marrow failure syndrome associated with increased risk of myelodysplasia (MDS) and acute myeloid leukemia (AML). The aim of this multi-institutional retrospective study was to investigate clinical features, treatment, and outcomes of 37 patients with SDS who developed MDS or AML. Diagnosis of SDS was established by SBDS genetic testing (n=30), exocrine pancreatic dysfunction (n=5), or data were unavailable (n=2). Nine individuals presented with AML (4 male, 5 female), 26 with MDS (13 male and 13 female), one male with refractory cytopenia (RC), and one male with isolated persistent somatic TP53 mutation. Eight of 26 MDS patients, had MDS-EB1 or EB2 at diagnosis, of whom two progressed to AML. Three patients initially presenting with early MDS progressed to MDS-EB1, MDS-EB2, or AML. Median age (years) at diagnosis of early MDS was 13.8 (range 0.5-28.8), for MDS-EB1/2 was 16 (range 9-30) and for AML was 33 (range 5.5-47). Nine patients with MDS and 1 patient with AML were receiving G-CSF chronically prior to diagnosis of MDS/AML.Complex cytogenetics, (>3 cytogenetic abnormalities per clone), were noted in 8/9 AML cases. One AML patient presented with normal cytogenetics. Complex clonal cytogenetic abnormalities were noted in 5 of 6 patients with MDS-EB1/EB2 for whom reports were available. Cytogenetic data were available for 16 MDS cases and clonal abnormalities were noted in 10. Aberrations involving chromosome 7 were most common. The patient with the somatic TP53 mutation had normal cytogenetics. Centralized bone marrow pathology review is currently ongoing.Follow up data were available for 8 patients with AML; 6 are deceased. Six received chemotherapy with intent to proceed to hematopoietic stem cell transplant (HSCT), of whom 5 failed to achieve remission and died with disease without proceeding to transplant. One AML patient proceeded to HSCT with progressive disease post-chemotherapy, but died with relapsed disease. One patient proceeded to HSCT without prior chemotherapy and was in remission at day 30 post-HSCT. The sole long-term surviving AML patient achieved remission with chemotherapy and underwent HSCTs with 3 separate stem cell infusions due to primary graft failure after the initial two infusions. He remains alive in remission more than 4 years after diagnosis. Notably this surviving AML patient was the only AML patient with normal cytogenetics at diagnosis.Follow up data are available for 6 of 8 patients presenting with MDS-EB1/EB2, 4 of whom are deceased. One patient who presented with MDS-EB1 is alive with relapsed disease after HSCT and one patient is in remission 100 days after HSCT.Follow up data are available for 17 of 18 early MDS patients, 7 of whom are deceased including three who had progressed to MDS-EB1, MDS-EB2, or AML. Four of the 7 deceased patients had received a HSCT. One individual with MDS died of hepatic failure unrelated to MDS. Seven MDS patients are alive in remission after HSCT without prior chemotherapy. Treatment was not reported for an additional 2 surviving patients. One patient receiving a hypomethylating agent is alive with stable disease 4.8 years from diagnosis. The patients with RC and with a TP53 clonal abnormality are alive at 6.5 years and 1.7 years from diagnosis respectively.In summary,prognosis is poor for patients with SDS who develop AML or MDS-EB1/2, with few long-term survivors due to resistant disease and treatment-related complications. Outcomes are better if transplanted for MDS prior to acquisition of increased blasts, with 10 of 17 (59%) subjects surviving (median follow up 6 years, range 1.5-11.2). AML often presents in adulthood highlighting the need for continued surveillance of SDS patients with bone marrow examinations including cytogenetics and FISH. These data demonstrate the importance of early detection of clonal evolution in this leukemia predisposition syndrome. Better markers for risk stratification are needed to identify patients who would benefit from early transplant prior to advanced clonal disease. Novel therapeutic strategies, such as targeted therapies, are urgently needed to improve outcomes of SDS patients with advanced MDS or AML. DisclosuresDiNardo:Daiichi-Sankyo: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Norkin:Celgene: Honoraria, Research Funding. Shimamura:TransCellular Therapeutics: Other: Spouse is majority shareholder .