Against Acute Myeloid Leukemia Research Articles

Venetoclax acts as an immunometabolic modulator to potentiate adoptive NK cell immunotherapy against leukemia

Natural killer (NK) cell-based immunotherapy holds promise for cancer treatment; however, its efficacy remains limited, necessitating the development of alternative strategies. Here, we report that venetoclax, an FDA-approved BCL-2 inhibitor, directly activates NK cells, enhancing their cytotoxicity against acute myeloid leukemia (AML) both invitro and invivo, likely independent of BCL-2 inhibition. Through comprehensive approaches, including bulk and single-cell RNA sequencing, avidity measurement, and functional assays, we demonstrate that venetoclax increases the avidity of NK cells to AML cells and promotes lytic granule polarization during immunological synapse (IS) formation. Notably, we identify a distinct CD161lowCD218b+ NK cellsubpopulation that exhibits remarkable sensitivity to venetoclax treatment. Furthermore, venetoclax promotes mitochondrial respiration and ATP synthesis via the NF-κB pathway, thereby facilitating IS formation in NK cells. Collectively, our findings establish venetoclax as a multifaceted immunometabolic modulator of NK cell function and provide a promising strategy for augmenting NK cell-based cancer immunotherapy.

Antileukemia Activity of Human Natural Killer Cell-Derived Nanomagic Bullets against Acute Myeloid Leukemia (AML).

Background: Cancer is among the serious health problems of the medical world, for treatment of which severe treatments are used. However, the prognosis of cancer patients is still poor. The application of NK cell-derived exosomes (NK-Exo) is a new method for cancer immunotherapy. These nanoparticles with a size range of 30-120 nm are a small model of mother cells. In this study, the anti-tumor activity of NK-Exo and LAK-Exo (activated NK cell-derived exosome) against acute myeloid leukemia (AML) is investigated in vitro. Materials and Methods: The MACS method was performed for the separation of NK cells from the buffy coats of healthy donors, and an EXOCIBE kit was used for the isolation of NK-Exo. After treating the KG-1 cell line with different doses of NK-Exo, MTT assay, and annexin V-PE were done to evaluate cell proliferation and apoptosis, respectively, and for confirmation of involved proteins, Real-Time PCR and western blotting were performed. Results: Anti-tumor activity of NK-Exo and LAK-Exo was dose- and time-dependent. Their highest activities were observed following 48 hours of incubation with 50 µg/ml exosome (p<0.0001). However, this cytotoxic activity was also seen over a short period of time with low concentrations of NK-Exo (p<0.05) and LAK-Exo (p<0.001).The cytotoxic effect of LAK-Exo on target cells was significantly higher than NK-EXO. The induction of apoptosis by different pathways was time-point dependent. Total apoptosis was 34.56% and 51.6% after 48 hours of tumor cell coculture with 50µg/ml NK-Exo and LAK-Exo, respectively. Significant expression of CASPASE3, P38, and CYTOCHROME C genes was observed in the cells treated with 50 µg/ml NK-Exo and LAK-Exo. Conclusion: Our study confirmed the antileukemia activity of NK-Exo against AML tumor cells in vitro. Therefore, NK-Exo can be considered as a promising and effective treatment for leukemia therapy.

Abstract 5227: Gamma-delta (γδ) CAR-T cells lacking the CD3ζ signaling domain enhance targeted killing of AML cells and preserve healthy tissues

Abstract Chimeric antigen receptor T cell (CAR-T) therapy has shown remarkable efficacy against B cell malignancies, offering hope to patients with limited treatment options. However, extending this therapy to myeloid malignancies and solid tumors has proven challenging due to co-expression of targetable antigens on hematopoietic progenitors and healthy tissues. In this context, γδ T cells show promise, as they can directly identify and eliminate malignant cells via recognition of multiple tumor-associated stress antigens rarely expressed on normal tissues. We leveraged the tumor-sensing capabilities of γδ T cells with enhanced tumor localization by employing a non-signaling CAR (nsCAR) that excludes the CD3ζ domain, facilitating targeted tumor cell killing while sparing healthy tissues. We designed second-generation lentiviral constructs for anti-CD33-scfv for in vitro evaluation against acute myeloid leukemia (AML) lines HL-60, KG-1a, and MOLM-13 and the chronic myeloid leukemia (CML) line K-562 Additionally, we tested CD33/CD123 dual-targeting nsCAR constructs (ns-dCAR) to determine if the addition of CD123 targeting enhanced the therapeutic index. We also tested whether a secreted IL-15 (sIL-15) would enhance CAR-T cell fitness. We observed significant upregulation of CD69 in Jurkat cells transduced with signaling CARs in co-culture with KG-1a cells but not in those with nsCAR constructs. We also noticed a time-dependent reduction (43%) in the CD3ζ+ CD33CAR+ population over a 7-day extended coculture while the nsCAR+ Jurkat population remained stable, suggesting potential mitigation of activation-induced cell death (AICD). Expanded and activated γδ T cells from healthy donors were then transduced with nsCAR lentiviral vectors. The ns33CAR+ γδ T cells exhibited enhanced killing capability against HL-60 (up to 1.3x) and K-562 (up to 1.6x) compared to unmodified γδ T cells (UTD) in a 24-hour cytotoxicity assay. Incorporation of sIL-15 into the nsCD33 CAR construct also increased killing across all 4 cell lines (up to 1.8x for HL-60, up to 2.6x for KG-1a, up to 2.0x for MOLM-13 and up to 2.0x for K-562). Minimal cytotoxicity (&amp;lt;10%) was observed for nsCARs or UTDs against normal CD33+/CD123+ cells from healthy donor PBMC or CD34+ HPSCs. The ns-dCAR constructs did not improve in vitro AML killing compared to ns33CAR alone, although ns-dCARs generally exhibited lower transduction efficiency. In summary, our findings suggest that combining nsCAR constructs with γδ T cells may widen the therapeutic window to expand the reach of CAR-T therapy to cancers with limited target antigen expression on critical healthy tissues. Further optimization to improve integration and incorporation of membrane-bound IL-15 co-expression holds the potential to enhance both the efficacy and safety profiles of next-generation adoptive cell therapies against a broader spectrum of cancers. Citation Format: Lei Ding, Yanjie Li, Jiexue Li, Mariska Ter Haak, Lawrence Lamb. Gamma-delta (γδ) CAR-T cells lacking the CD3ζ signaling domain enhance targeted killing of AML cells and preserve healthy tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5227.

Combating Acute Myeloid Leukemia via Sphingosine Kinase 1 Inhibitor-Nanomedicine Combination Therapy with Cytarabine or Venetoclax.

MP-A08 is a novel sphingosine kinase 1 (SPHK1) inhibitor with activity against acute myeloid leukemia (AML). A rationally designed liposome-based encapsulation and delivery system has been shown to overcome the physicochemical challenges of MP-A08 and enable its effective delivery for improved efficacy and survival of mice engrafted with human AML in preclinical models. To establish therapies that overcome AML's heterogeneous nature, here we explored the combination of MP-A08-loaded liposomes with both the standard chemotherapy, cytarabine, and the targeted therapy, venetoclax, against human AML cell lines. Cytarabine (over the dose range of 0.1-0.5 µM) in combination with MP-A08 liposomes showed significant synergistic effects (as confirmed by the Chou-Talalay Combination Index) against the chemosensitised human AML cell lines MV4-11 and OCI-AML3. Venetoclax (over the dose range of 0.5-250 nM) in combination with MP-A08 liposomes showed significant synergistic effects against the chemosensitised human AML cell lines, particularly in venetoclax-resistant human AML cells. This strong synergistic effect is due to multiple mechanisms of action, i.e., inhibiting MCL-1 through SPHK1 inhibition, leading to ceramide accumulation, activation of protein kinase R, ATF4 upregulation, and NOXA activation, ultimately resulting in MCL-1 degradation. These combination therapies warrant further consideration and investigation in the search for a more comprehensive treatment strategy for AML.

Bone marrow-derived mesenchymal stromal cells obstruct AML-targeting CD8+ clonal effector and CAR T-cell function while promoting a senescence-associated phenotype

Bone marrow mesenchymal stromal cells (MSCs) have been described as potent regulators of T-cell function, though whether they could impede the effectiveness of immunotherapy against acute myeloid leukemia (AML) is still under investigation. We examine whether they could interfere with the activity of leukemia-specific clonal cytotoxic T-lymphocytes (CTLs) and chimeric antigen receptor (CAR) T cells, as well as whether the immunomodulatory properties of MSCs could be associated with the induction of T-cell senescence. Co-cultures of leukemia-associated Wilm’s tumor protein 1 (WT1) and tyrosine-protein kinase transmembrane receptor 1 (ROR1)-reactive CTLs and of CD123-redirected switchable CAR T cells were prepared in the presence of MSCs and assessed for cytotoxic potential, cytokine secretion, and expansion. T-cell senescence within functional memory sub-compartments was investigated for the senescence-associated phenotype CD28−CD57+ using unmodified peripheral blood mononuclear cells. We describe inhibition of expansion of AML-redirected switchable CAR T cells by MSCs via indoleamine 2,3-dioxygenase 1 (IDO-1) activity, as well as reduction of interferon gamma (IFNγ) and interleukin-2 (IL-2) release. In addition, MSCs interfered with the secretory potential of leukemia-associated WT1- and ROR1-targeting CTL clones, inhibiting the release of IFNγ, tumor necrosis factor alpha, and IL-2. Abrogated T cells were shown to retain their cytolytic activity. Moreover, we demonstrate induction of a CD28loCD27loCD57+KLRG1+ senescent T-cell phenotype by MSCs. In summary, we show that MSCs are potent modulators of anti-leukemic T cells, and targeting their modes of action would likely be beneficial in a combinatorial approach with AML-directed immunotherapy.

Unprecedented sesquiterpene-polycyclic polyprenylated acylphloroglucinol adduct against acute myeloid leukemia via inhibiting mitochondrial complex V

Monosescinol A (1), the first example of sesquiterpene–polycyclic polyprenylated acylphloroglucinol (PPAP) adduct, which represented a new subclass of PPAP-type natural products, along with two new congeners with normal spiro 6/6/5 tricyclic architecture, were isolated from Hypericum longistylum. Monosescinol A possessed an unprecedented 6/5/5/6/6 pentacyclic carbon skeleton that might be assembled from the 6/6/5 carbon skeleton, via the splitting decomposition of C-3/C-14, and the attack from the C-3 in the PPAP core to C-28 in sesquiterpene section. In addition, we have firstly confirmed that 24R configuration was existed in sec‑Bu containing PPAPs by single crystal diffraction data analysis of monosescinol B (2), that might provide an enlightenment in the configurational determination of sec‑Bu containing PPAPs. Significantly, further pharmacological research has found that compound 1 exhibited remarkable pharmacological effects against acute myeloid leukemia (AML) cell lines, with direct inhibition of mitochondrial complex V and an increase in mitochondrial membrane potential, and led to an induction of oxidative stress, endogenous inflammation, and apoptosis of AML cells.

Conditioning Impacts on Regulatory T-Cells (Tregs) in the Microenvironment of AML: Observations from the Phase 1 Cynk-001-AML-001 Trial

Introduction: Evidence shows that NK cells can exhibit potent anti-tumor activity against acute myeloid leukemia (AML). CYNK-001 is a CD56+CD3- enriched, off-the-shelf, allogeneic natural killer (NK) cell therapy expanded from placental CD34 cells. The use of recombinant IL-2 (rhIL-2) therapy has induced regression of tumors by stimulating the activation and proliferation of NK cells. Low dose RhIL-2 has been shown to selectively expand and enhance the expression of maturation markers on the surface of NK cells, making them more potent killers in vitro and in vivo. CYNK-001-AML-001 is a Phase I multi-dose study evaluating the safety, tolerability, and persistence of CYNK-001 with or without rhIL-2 in adults with primary or secondary acute myeloid leukemia (AML) in morphologic complete remission (CR) with minimal residual disease (MRD) or relapsed/refractory (R/R) AML Aim: To determine the safety and tolerability of rhIL-2 when added to CYNK-001 and assess the impact of rhIL-2 on CYNK-001 activity and persistence. Methods This Phase I, single-arm, dose escalation clinical trial (NCT04310592) enrolled patients 18-80 years with R/R AML or MRD-positive CR. Escalating doses of CYNK-001 cells were administered following a standard 3+3 design, with 2 separate arms (MRD+ and R/R AML). Cohort 4a enrolled MRD+ AML subjects, while cohorts 4b and 5b enrolled R/R AML subjects. Cohort 4a and 4b utilized a dose of 1.8 billion CYNK-001 x 3 doses of CYNK-001 without rhIL-2. Cohort 5b utilized same dose of CYNK-001 along with rhIL-2. The decision to administer rhIL-2 in cohorts 6a, 6b, 7a and 7b would be based on review of safety, efficacy, and translational data in Cohorts 5b. In cohort 5b rhIL-2 was administered at a dose of 6M IU on days 0,2,4,7,9,11 and 14. Cohort 4b was used as a comparator. Results Five patients in cohort 5b received rhIL-2. Treatment was well tolerated with no dose limiting toxicities (DLT's) being observed. Ten adverse events ≥ grade 3 were experienced. The commonest grade 3 AE's were raised AST (2/10) and ALT (2/10). Two grade 4 AE's were reported including febrile neutropenia and a pre-existing GVHD. In cohort 4b, 3 out of 6 patients achieved an objective response (3x MLFS) at day 28. No patient in cohort 5b achieved a response. While there was an apparent higher baseline blast count in cohort 5b which may have contributed to the differences, translational data demonstrated a surge in Tregs without enhancement of T helper or cytotoxic cells or NK cell reconstitution. In cohort 4a, one subject who received rhIL-2 (6MIU/dose) in error showed an increase in Tregs similar to cohort 5b. Conclusion Treatment with CYNK-001 in combination with rhIL-2 was well tolerated with no dose-limiting toxicities observed. However, this approach does not enhance CD4 helper T cells, CD8 cytotoxic cells or NK cell reconstitution, while stimulated proliferation of Tregs. CYNK-001 proliferation and persistence was not enhanced with rhIL-2 infusion. Based on these data, rIL-2 was excluded from subsequent cohorts in this study.

Impact of previous anthracycline therapy in patients with acute myeloid leukemia receiving venetoclax.

Venetoclax (VEN) combination regimens are now recognized as effective against acute myeloid leukemia (AML). However, the prognosis of patients who do not attain a composite complete response (cCR) is extremely poor, and clinical determinants of response remain unknown. Medical records of 57 patients with AML treated with VEN combination regimens from April 2021 to March 2022 at six institutions were retrospectively analyzed. The primary endpoint was cCR, complete remission, or complete remission with incomplete hematologic recovery after one cycle of VEN combination regimen. Five patients had previously relapsed after allogeneic hematopoietic stem cell transplantation (allo-SCT). The treatment regimen was azacitidine-VEN in 48 patients (84%) and low-dose cytarabine-VEN in 9 patients (16%). Thirty patients (53%) achieved cCR after one cycle of a VEN regimen. In univariate analysis, the number of prior chemotherapy regimens, post-allo-SCT relapse, and cytogenetic risk category were associated with a decreased likelihood of achieving cCR. In multivariate analysis, second-line chemotherapy remained a significant predictor of response. Patients who received anthracycline immediately before the VEN regimen had a higher cCR rate than patients who did not receive anthracycline. In this study, prior chemotherapy/allo-SCT and cytogenetic risk were associated with VEN treatment outcomes.

Repurposing Atovaquone as a Therapeutic against Acute Myeloid Leukemia (AML): Combination with Conventional Chemotherapy Is Feasible and Well Tolerated

Survival of pediatric AML remains poor despite maximized myelosuppressive therapy. The pneumocystis jiroveci pneumonia (PJP)-treating medication atovaquone (AQ) suppresses oxidative phosphorylation (OXPHOS) and reduces AML burden in patient-derived xenograft (PDX) mouse models, making it an ideal concomitant AML therapy. Poor palatability and limited product formulations have historically limited routine use of AQ in pediatric AML patients. Patients with de novo AML were enrolled at two hospitals. Daily AQ at established PJP dosing was combined with standard AML therapy, based on the Medical Research Council backbone. AQ compliance, adverse events (AEs), ease of administration score (scale: 1 (very difficult)-5 (very easy)) and blood/marrow pharmacokinetics (PK) were collected during Induction 1. Correlative studies assessed AQ-induced apoptosis and effects on OXPHOS. PDX models were treated with AQ. A total of 26 patients enrolled (ages 7.2 months-19.7 years, median 12 years); 24 were evaluable. A total of 14 (58%) and 19 (79%) evaluable patients achieved plasma concentrations above the known anti-leukemia concentration (>10 µM) by day 11 and at the end of Induction, respectively. Seven (29%) patients achieved adequate concentrations for PJP prophylaxis (>40 µM). Mean ease of administration score was 3.8. Correlative studies with AQ in patient samples demonstrated robust apoptosis, OXPHOS suppression, and prolonged survival in PDX models. Combining AQ with chemotherapy for AML appears feasible and safe in pediatric patients during Induction 1 and shows single-agent anti-leukemic effects in PDX models. AQ appears to be an ideal concomitant AML therapeutic but may require intra-patient dose adjustment to achieve concentrations sufficient for PJP prophylaxis.

Design and synthesis of selective FLT3 inhibitors via exploration of back pocket II.

Aim: The clinical benefits of FLT3 inhibitors against acute myeloid leukemia (AML) have been limited by selectivity and resistance mutations. Thus, to identify FLT3 inhibitors possessing high selectivity and potency is of necessity. Methods & results: The authors used computational methods to systematically compare pocket similarity with 269 kinases. Subsequently, based on these investigations and beginning with in-house compound 10, they synthesized a series of 6-methyl-isoxazol[3,4-b]pyridine-3-amino derivatives and identified that compound 45 (IC50: 103 nM) displayed gratifying potency in human AML cell lines with FLT3-internal tandem duplications mutation as well as FLT3-internal tandem duplications-tyrosine kinase domain-transformed BaF3 cells. Conclusion: The integrated biological activity results indicated that compound 45 deserves further development for therapeutic remedies for AML.

Identification of second generation benzylidene chromanone analogues as novel, potent DHODH inhibitors in acute myeloid leukemia cells

Dihydroorotate dehydrogenase (DHODH) remains as an active target at the preclinical level against acute myeloid leukemia (AML). Herein we report potent second generation benzylidene chromanone (SBL-105) analogues to inhibit DHODH in AML cells. Virtual docking and molecular dynamic simulations were performed. Human-recombinant (rh)DHODH, THP-1, TF-1 and HL-60 cell lines were used. MTT assay was used for cell viability. Flow cytometry was used for differentiation analysis. Computational modeling and simulations predict, SBL-105 analogs bind efficiently to DHODH with improved binding energies. While all tested analogues of SBL-105 inhibited rh DHODH enzyme, SBL-105-4 and SBL-105-6 more effectively inhibited rh DHODH with an IC50 value of 3.62 and 13.61 nM respectively. SBL-105-4 exhibited excellent anti proliferative effects against THP-1, TF-1 and HL-60 cells with GI50 values of 18.78, 38.11 and 63.83 nM respectively. A similar effect was also observed in SBL-105-6 treated AML cells with respective GI50 values of 34.56, 44.40 and 38.65 nM in THP-1, TF-1 and HL-60 cells. An increase in apoptotic populations were enumerated in all three AML cells. Both these compounds also increased the differentiation marker CD11b positive populations in all the three AML cells tested. In conclusion, SBL-105-4 and SBL-105-6 were identified as potent second generation DHODH inhibitors, which drives attention for further preclinical developments. Communicated by Ramaswamy H. Sarma

Special issue: CAR‐T cell therapy for hematological malignancies

Chimeric antigen receptor T (CAR-T) cell therapy has revolutionized the treatment of relapsed/refractory (R/R) B-cell derived hematological malignancies, including acute lymphoblastic leukemia (ALL), B-cell non-Hodgkin lymphoma (B-NHL), and multiple myeloma (MM). CD19-targeted CAR-T cells yield complete remission (CR) rates of about 90% in R/R ALL and about 50% in R/R NHL, respectively, while BCMA-targeted CAR-T cells yield CR rate of about 50%−80% in R/R MM. Notably, the US Food and Drug Administration have approved six CAR-T cell products (tisagenlecleucel, axicabtagene ciloleucel, brexucabtagene autoleucel, lisocabtagene maraleucel, idecabtagene vicleucel, and ciltacabtagene autoleucel) for the treatment of R/R B-NHL, R/R ALL, and R/R MM. However, some patients might not respond to such therapy or quickly relapse after CAR-T cell infusion, which is likely due to the dysfunction and poor persistence of CAR-T cells or the modulation of specific antigen. Thus, alternative treatment strategies must be investigated. In addition, accumulating research have been conducted to discover novel target of antigens with therapeutic efficacy and utility for generating CAR-T cells against acute myeloid leukemia (AML). Safety during CAR-T cell treatment is another important issue, concerning complications such as cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome (ICANS), pancytopenia, and infection. Despite the fact that the majority of those adverse effects are minimal, the risk of a life-threatening situation still exists. Cautious treatment for severe adverse events requires a multidisciplinary approach with involvement of not only oncologists but also other internal medicine doctors to guarantee diagnosis and treatment in time. Therefore, it is of vital importance to understand the novel advances of CAR-T cell therapy. This special issue of ImmunoMedicine focuses on novel developments of CAR-T cell therapy for hematological malignancies. The review from Xiangmin Wang (https://doi.org/10.1002/imed.1030) summarized the non-BCMA targeted CAR-T cell therapies for MM. Novel targets including CS1, CD38, CD138, NKG2D, CD70, TACI, and etc. might have the potential to prevent the recurrence and enhance treatment efficiency. The review from Elaine Tan Su Yin (https://doi.org/10.1002/imed.1039) summarized the current breakthrough and future perspectives of CD20-targeted CAR-T cell therapy for hematologic malignancies, especially for R/R B-NHL. The review from Yue Huang (https://doi.org/10.1002/imed.1031) summarized the current achievement and potential AML-associated cell markers of CAR-T cell therapy in AML preclinical studies and clinical trials, and discusses the future directions of CAR-T cell therapy in patients with AML. The review from Yuanyuan Hao (https://doi.org/10.1002/imed.1029) summarized the effects of tumor-derived exosomes (TEXs) on the survival and functions of T cell subsets, as well as their clinical applications. This special issue also contains three original research articles reporting clinical trials of CAR-T cell therapy. Linghui Zhou et al. (https://doi.org/10.1002/imed.1036) reported the data of infections post CAR-T cell therapy, and found that it was a common complication in patients with hematological malignancies treated by CD19 CAR-T cells, which means clinicians should pay more attention to such situations. Kaiting Tang et al. (https://doi.org/10.1002/imed.1037) presented three cases of compassionate CAR-T cell therapy in advanced B-ALL, and shared their experiences on treating patients with high disease burden. Yue Huang et al. (https://doi.org/10.1002/imed.1032) reported an R/R ALL patient with high leukemia burden and central nervous system involvement, who responded to donor-derived HLA-matched allogeneic CAR-T treatment and achieved quick CR. We thank all the authors for their insightful contributions. This special issue provides an overview of the current knowledge regarding the most recent advances of CAR-T cell therapy, including CAR-T cell function, diverse applications, and complications with coping strategies. We hope that this issue will appeal to researchers as they explore fundamental and clinical aspects of CAR-T cell therapy.

GC/MS characterization and computational kinome-wide screening of pomegranate fruit extract identifies key phytochemicals interacting to CDK kinases implicated in acute myeloid leukemia cells.

Punica granatum (Pomegranate fruit) and its constituents are proven effective against various cancer types. However, a kinome-wide screening for the active phytochemicals against kinases is not reported. This study aims in validating pomegranate fruit extract (PFE) against acute myeloid leukemia (AML) cells, and computationally identifying the phytochemicals interacting with active kinases. PFE was made with Soxhlet extractor using absolute ethanol. Gas-chromatography-mass spectroscopy (GC-MS) for phytochemical identification and MTT assay for cytotoxicity in AML (THP-1, TF-1 and HL-60) cells were performed. Apoptosis, CDK5 and CDK8 were assessed with flow cytometry. Kinase profiling was performed using In silico kinome screening. GC-MS analysis revealed 38 bioactive phytochemicals in PFE including pyrazoles, aldehydes, phenols, esters, pyranosides, and octadecadienoic acids. The extract inhibited the AML cell proliferations with GI50 values of 195.5μg/ml, 289.1μg/ml, and 353.5μg/ml in THP-1, THP-1, and HL-60 cells, respectively. PFE also exhibited a dose-responsive increase in apoptotic cell populations when treated to the AML cells. Computational screening and modeling predicted three critical constituents, viz., Deoxyartemisinin, 3-Methyl-3-phenyl-3H-indazole, and 8-fluoro-5,6-dimethoxy-3,4-dihydro-2H-naphthalen-1-one of pomegranate extract to interact mainly with cyclin-dependent kinases, including CDK5 and CDK8. Proteinand ligand docking predicted binding energies, and binding pose for top candidate lead molecules. In vitro assay exhibited the anticancer properties of PFE in AML cells. Computational kinome screening predicted top three PFE constituents targeting CDKs which may be responsible for the demonstrated anticancer efficacy of the extract against AML. This hypothesis further aligned with observed efficacy of PFE to inhibit CDK5 and CDK8 in all AML cells tested. PRACTICAL APPLICATIONS: Though Punica granatum (Pomegranate fruit) and its constituents are proven effective against various cancer types, a kinome-wide screening for the active phytochemicals against kinases is not reported. In this study, we have conducted GC/MS characterization of the active phytochemicals of PFE and have performed a kinome-wide screening for all the 38 identified compounds toward 310 active kinases commonly expressed in cancers. These observations warrant isolation and further evaluation of these phytochemicals or their analogues as effective CDK inhibitors against AML proliferation. Further, the computational methods used in this study will throw light on literature for new options of kinome panel screening of active phytochemicals or small molecules.

Structure-Based Discovery and Optimization of Furo[3,2-c]pyridin-4(5H)-one Derivatives as Potent and Second Bromodomain (BD2)-Selective Bromo and Extra Terminal Domain (BET) Inhibitors

Pan-bromodomain and extra terminal (Pan-BET) inhibitors show profound efficacy but exhibit pharmacology-driven toxicities in clinical trials. The development of domain-selective BET inhibitors to separate efficacy and toxicity is urgently needed. Herein, we report a series of furo[3,2-c]pyridin-4(5H)-one derivatives as novel BD2-selective BET inhibitors. The representative compound 8l (XY153) potently bound to BRD4 BD2 with an half-maximum inhibitory concentration (IC50) value of 0.79 nM and displayed 354-fold selectivity over BRD4 BD1. Besides, 8l exhibited 6-fold BRD4 BD2 domain selectivity over other BET BD2 domains. Compound 8l displayed potent antiproliferative activity against multiple tumor cell lines, especially MV4-11 (IC50 = 0.55 nM), while showing weak cytotoxicity against the normal lung fibroblast cell line. It highlights the safety profile of this series of BD2 inhibitors. 8l also demonstrated good metabolic stability in vitro. These data indicate that 8l may serve as a new and valuable lead compound for the development of potential therapeutics against acute myeloid leukemia (AML).

Vitamin C promotes anti-leukemia of DZNep in acute myeloid leukemia

The epigenetic treatment by 3-Deazaneplanocin A (DZNep), a histone methyltransferase inhibitor, shows great potential against acute myeloid leukemia (AML). However, the variant sensitivity and incomplete response to DZNep are commonly observed. Here, we reveal that vitamin C (Vc) dramatically promotes DZNep response against leukemic cells in different cell lines and primary AML samples. Vc enhances apoptosis and differentiation induced by DZNep in different AML cell lines in vitro and reduces leukemia progression in vivo. At the molecular level, Vc downregulates an enzyme of serine synthesis named D-3-phosphoglycerate dehydrogenase (PHGDH), as well as BCL2, an anti-apoptotic gene. Over-expression of PHGDH reverses the Vc-enhanced anti-leukemic effect of DZNep in AML cells. Therefore, our findings provide an effective approach to reduce the resistance against epigenetic treatment by Vc, which shows a potential improvement of their combination in AML patients.

Degrading FLT3-ITD protein by proteolysis targeting chimera (PROTAC)

Clinical FLT3 mutations caused poor therapeutic benefits toward the present FLT3 inhibitors, and degradation of the FLT3 mutant protein may be a promising alternative approach to protect against acute myeloid leukemia (AML). Herein, we report the discovery of small molecule FLT3 degraders based on the proteolysis targeting chimera (PROTAC). FLT3 degraders were designed, synthesized, and evaluated for FLT3 degradation. Promising PF15 significantly inhibited the proliferation of FLT3-ITD-positive cells, induced FLT3 degradation and downregulated the phosphorylation of FLT3 and STAT5. An in vivo xenograft model and survival period evaluation verified the efficacy of PROTAC. These findings laid a robust foundation for FLT3-PROTAC molecules as an effective strategy for treating AML.

Palbociclib and Ponatinib Suppress Acute Myeloid Leukemia in Patient-Derived Xenograft

Aims: Palbociclib, a breast cancer approved CDK4/6 inhibitor, and ponatinib, a BCR/ABL1 inhibitor with a multi-kinase activity approved for chronic myeloid and acute lymphoid leukemia, were previously shown to be effective in vitro against acute myeloid leukemia (AML). Here, we aimed to test this effect in a patient-derived xenograft model.Methods: Two newly diagnosed AMLs (AML #1: myelomonocytic AML, intermediate cytogenetic risk; AML #2: AML with myelodysplasia-related changes, poor cytogenetic risk) were xenotransplanted into NOD SCID gamma mice. Treatment was initiated at detection of approximately 5-20% hCD45+ cells in mouse peripheral blood (PB). Palbociclib, ponatinib, vehicle, and venetoclax as a comparative treatment, were administered orally for 3 weeks, 5 days per week. Chemotherapy (cytarabine+doxorubicine, AraC/Dox) 5+3 regimen served as a positive control. Azacitidine served as another comparative drug and was administered subcutaneously, five days per week in 3 cycles - 1 week on, 1 week off.Results: Significant reduction of disease burden and prolongation of overall survival (OS) were seen with palbociclib and the reference treatment venetoclax in both AMLs, and with chemotherapy in AML#1 (Fig. 1). Ponatinib prolonged OS in AML#1 but failed to provide reduction of disease burden in PB. Interestingly, azacitidine induced the longest remission (<1% hCD45+ cells in PB), for almost 10 weeks, but only in 2/4 mice for AML#2. Treatment toxicity manifested by weight decrease was only seen with chemotherapy (AML#1: 24% weight loss, p = 0.0001; AML#2: 19% loss, p = 0.04), and was also accompanied with early mouse mortality in 3/4 mice for AML#2. None of the tested treatments lead to complete AML eradication and a gradual relapse was seen in PB. The AML infiltration was higher in bone marrow than in spleen at final analysis at relapse (AML#1, 83 vs 73% of hCD45+ cells, mean, p = 0.02; AML#2, 95 vs 65%, p = 0.0001). No changes in AML phenotype were observed between treated and vehicle mice in case of AML#1, except for azacitidine which decreased monocyte (SSCdim, CD45high; 94 vs 96%, mean, p = 0.03), CD34+ (2 vs 5%, p = 0.01) and primitive CD34+CD38- cell (0.1 vs 0.3%, p = 0.005) percentages. For AML#2, blast (SSClow, CD45dim) percentage compared to vehicle (70%) was decreased by chemotherapy (24%, p = 0.01) and increased by venetoclax (80%, p = 0.03) and azacitidine (87%, p = 0.03); monocytes (6% for vehicle) were decreased by chemotherapy (1%, p = 0.004), venetoclax (3%, p = 0.01), and azacitidine (0%, p = 0.008); CD34+ cells were increased by venetoclax (59 vs 39%, p = 0.02).Summary: Palbociclib, and partially ponatinib, demonstrated AML suppression in vivo. This encourages further investigation of their efficacy in different AML subtypes and in combination with other drugs.Funding: Supported by MUNI/A/1595/2020. [Display omitted] DisclosuresMayer: AOP Orphan Pharmaceuticals: Research Funding.

A Phase I Trial of the Antibody-Cytokine Fusion Protein F16IL2 in Combination with Anti-CD33 Immunotherapy for Posttransplant AML Relapse

IntroductionNatural killer (NK) cells are key effectors in cancer immunosurveillance and posttransplant immunity, but shortage of environmental growth factors and deficient recognition of malignant cells may limit their anticancer efficacy. We hypothesized that the antibody-mediated anchoring of interleukin-2 (IL-2) to the leukemia-modified extracellular matrix (ECM) would increase NK cell abundance and activity to potentiate antibody-dependent cellular cytotoxicity (ADCC) against acute myeloid leukemia (AML) blasts. In this novel-novel combination dose-escalation phase 1 trial, we enrolled patients with AML relapse after allogeneic hematopoietic stem cell transplantation (HSCT) to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary activity of F16IL2, an antibody-cytokine fusion protein composed of the human antibody fragment scFv(F16) in diabody format and two molecules of human IL-2, in combination with the Fc-optimized, ADCC-mediating anti-CD33 monoclonal antibody BI 836858. F16 specifically targets the A1 domain of the ECM protein tenascin C (TnC), which is spliced into the TnC molecule during active angiogenesis and tissue remodeling while it is virtually absent in normal tissues.MethodsF16IL2 (10 - 20 Mio IU IV) was administered on days 1, 8, 15 and 22 of 28-day cycles, followed by administration of BI 836858 (10 - 40 mg IV) two days after each F16IL2 infusion. Dose escalation was performed over 4 dose levels (DL). Cohort 1 (10 Mio IU F16IL2 and 10 mg BI 836858, n = 5), cohort 2 (10 Mio IU F16IL2 and 20 mg BI 836858, n = 3), cohort 3 (20 Mio IU F16IL2 and 20 mg BI 836858, n = 4), cohort 4 (20 Mio IU F16IL2 and 40 mg BI 836858, n = 3). Safety and tolerability, pharmacodynamics and -kinetics, clinical efficacy and immune effector cell dynamics were investigated. This trial was registered at EudraCT as #2015-004763-37.ResultsBetween December 2016 and March 2020, 15 patients with a median age of 50 years (range, 20 - 68) were enrolled and treated across 4 dose levels. Six patients (40%) had received two or more prior HSCT. The most frequent drug-related AEs (F16IL2 or BI 836858 or combination) were pyrexia (n = 13, 87%), chills (n = 12, 80%) and infusion-related reactions (n = 9, 60%), consistent with the expected toxicity profile of cytokine-armed or naked mAbs. These events were generally manageable, transient and of grade ≤ 2. One dose-limiting toxicity occurred at each of DL 3 (pulmonary edema) and 4 (acute GVHD). No patient died within the first 30 days of treatment initiation. Whereas no formal maximum tolerated dose (MTD) was reached, the maximum tested dose of 20 Mio IU F16IL2 and 40 mg BI 836858 was considered the recommended dose (RD). Three objective responses (1 CR, 1 CRi, 1 PR in extramedullary AML) were observed among 7 patients treated at the two higher DL, whereas no responses occurred at the two starting DL. Median OS among all 15 patients was 4.8 months (1.5 - 12.9), with a 6- and 12-month OS of 40% and 27%, respectively. Among those 7 patients whose AML was at least temporarily controlled with study treatment (CR/CRi, PR, SD), 12-month OS was 67% vs. 0% in non-responders. Combination therapy stimulated the expansion and activation of NK cells in bone marrow and peripheral blood.ConclusionsTo the best of our knowledge, this is the first study demonstrating that the strategy of potentiating ADCC with tumor-targeted immunocytokines is feasible in humans. In the difficult-to-treat situation of posttransplant AML relapse, responses were observed at higher DL, even in patients with extramedullary disease. The antibody-mediated targeted delivery of IL-2 to the ECM combined with anti-CD33 immunotherapy represents an innovative experimental approach associated with acceptable safety and encouraging biologic and clinical activity in posttransplant AML relapse. DisclosuresWermke: Novartis, Roche, Pfizer, BMS: Consultancy, Honoraria, Research Funding. Hemmerle: Philogen S.p.A.: Current Employment. Schäfers: Philogen S.p.A.: Research Funding. Rossig: BMS and Celgene: Honoraria; Pfizer: Honoraria; Novartis: Honoraria; AdBoards by Amgen: Honoraria. Stelljes: Pfizer: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Celgene/BMS: Consultancy, Speakers Bureau; Medac: Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Rueter: Boehringer Ingelheim Pharma GmbH & Co. KG: Current Employment. Neri: Philogen S.p.A.: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: Multiple patents on vascular targeting; ETH Zurich: Patents & Royalties: CD117xCD3 TEA. Berdel: Philogen S.p.A.: Consultancy, Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees. Schliemann: Roche: Consultancy; Philogen S.p.A.: Consultancy, Honoraria, Research Funding; Astellas: Consultancy; Pfizer: Consultancy; BMS: Consultancy, Other: travel grants; Boehringer-Ingelheim: Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding; AstraZeneca: Consultancy; Abbvie: Consultancy, Other: travel grants.

Novel TCR-like CAR-T cells targeting an HLA∗0201-restricted SSX2 epitope display strong activity against acute myeloid leukemia

SummaryThe synovial sarcoma X breakpoint 2 (SSX2) belongs to a multigene family of cancer-testis antigens and can be found overexpressed in multiple malignancies. Its restricted expression in immune-privileged normal tissues suggest that SSX2 may be a relevant target antigen for chimeric antigen receptor (CAR) therapy. We have developed a T cell receptor (TCR)-like antibody (Fab/3) that binds SSX2 peptide 41-49 (KASEKIFYV) in the context of HLA-A∗-0201. The sequence of Fab/3 was utilized to engineer a CAR with the CD3 zeta intra-cellular domain along with either a CD28 or 4-1BB costimulatory endodomain. Human T cells from HLA-A2+ donors were transduced to mediate anti-tumor activity against acute myeloid leukemia (AML) tumor cells. Upon challenge with HLA-A2+/SSX2+ AML tumor cells, CAR-expressing T cells released interferon-γ and eliminated the tumor cells in a long-term co-culture assay. Using the HLA-A2+ T2 cell line, we demonstrated a strong specificity of the single-chain variable fragment (scFv) for SSX2 p41-49 and the closely related SSX3 p41-49, with no response against the others SSX-homologous peptides or unrelated homologous peptides. Since SSX3 has not been observed in tumor cells and expression cannot be induced by pharmacological intervention, SSX241-49 represents an attractive target for CAR-based cellular therapy to treat multiple types of cancer.

Development and characterization of a DNA aptamer for MLL-AF9 expressing acute myeloid leukemia cells using whole cell-SELEX

Current classes of cancer therapeutics have negative side effects stemming from off-target cytotoxicity. One way to avoid this would be to use a drug delivery system decorated with targeting moieties, such as an aptamer, if a targeted aptamer is available. In this study, aptamers were selected against acute myeloid leukemia (AML) cells expressing the MLL-AF9 oncogene through systematic evolution of ligands by exponential enrichment (SELEX). Twelve rounds of SELEX, including two counter selections against fibroblast cells, were completed. Aptamer pools were sequenced, and three candidate sequences were identified. These sequences consisted of two 23-base primer regions flanking a 30-base central domain. Binding studies were performed using flow cytometry, and the lead sequence had a binding constant of 37.5 + / − 2.5 nM to AML cells, while displaying no binding to fibroblast or umbilical cord blood cells at 200 nM. A truncation study of the lead sequence was done using nine shortened sequences, and showed the 5′ primer was not important for binding. The lead sequence was tested against seven AML patient cultures, and five cultures showed binding at 200 nM. In summary, a DNA aptamer specific to AML cells was developed and characterized for future drug-aptamer conjugates.