tapotoclax (AMG 176)

BH3 mimetics, including the BCL2/BCLXL/BCLw inhibitor navitoclax and MCL1 inhibitors S64315 and tapotoclax, have undergone clinical testing for a variety of neoplasms...Building on the observation that BH3 mimetic monotherapy induces AMP kinase (AMPK) activation in multiple acute leukemia cell lines, we report that the AMPK inhibitors (AMPKis) dorsomorphin and BAY-3827 sensitize these cells to navitoclax or MCL1 inhibitors...Conversely, dorsomorphin synergizes with navitoclax or the MCL1 inhibitor S63845 to induce cell death in primary acute leukemia samples ex vivo and increases the antitumor effects of navitoclax or S63845 in several xenograft models in vivo with little or no increase in toxicity in normal tissues. These results suggest that AMPK inhibition can sensitize acute leukemia to multiple BH3 mimetics, potentially allowing administration of lower doses while inducing similar antineoplastic effects.

P1, N=142, Active, not recruiting, Amgen | Trial primary completion date: Jan 2024 --> Sep 2024

P1, N=9, Completed, Amgen | Recruiting --> Completed | N=120 --> 9 | Trial completion date: Dec 2026 --> Dec 2023 | Trial primary completion date: Dec 2025 --> Dec 2023

P1, N=142, Active, not recruiting, Amgen | Recruiting --> Active, not recruiting

P1, N=175, Recruiting, Amgen | Trial completion date: Mar 2025 --> Aug 2024

We devised a novel augmentation on the conventional CRISPR/Cas9 KO/DO screen utilizing two MCL cell lines (Jeko1, Z138) which were both resistant to apoptosis induced by VEN +/- ibrutinib (IBR)(Fig 1)...The screen method was repeated in Jeko1 cells using the MCL1 inhibitor AMG176 and BCL-XL inhibitor A1331853, and again yielded BCL2 as well as novel hits, including MARCH5 KO as a sensitizing hit to BCL-XL inhibition...Degron dTAG-mediated depletion of MARCH5 demonstrated synergy with venetoclax in MOLM13 (AML) and Z138 (MCL) cell lines, and enhanced in vitro killing of MOLM13 by VEN + azacytidine, and killing of Jeko1 and Z138 by VEN + IBR...MARCH5 depletion also sensitizes blood cancer cell lines to BCL-XL inhibition. Addition of MARCH5 depletion to VEN-combination treatment improved MCL and AML killing in vitro, and this target should be prioritized for accelerated drug development.

P1, N=120, Recruiting, Amgen | Trial completion date: Mar 2026 --> Dec 2026 | Trial primary completion date: Mar 2025 --> Dec 2025

P1, N=175, Recruiting, Amgen | Trial completion date: Oct 2025 --> Mar 2025 | Trial primary completion date: Sep 2024 --> Dec 2023

One phytoconstituent, Isopongaflavone, was identified that exhibiting higher docking and drug-likeness than the already reported MCL1 inhibitor, Tapotoclax...This investigation proposes Isopongaflavone as a promising candidate for the development of innovative anticancer therapeutics, pending the necessary validation procedures. Also, the findings provide valuable information for designing MCL1 inhibitors based on the protein's structure.Communicated by Ramaswamy H. Sarma.

P1, N=175, Recruiting, Amgen | Trial completion date: Jan 2025 --> Oct 2025 | Trial primary completion date: Feb 2024 --> Sep 2024

No abstract available

AMG176 exhibited impressive synergy with venetoclax and chemotherapeutic agents, less so with proteasomal inhibitors, and antagonism with anti-CD20 monoclonal antibodies. The activity of AMG176 could not be confirmed in murine models of BCL. Combination therapy targeting MCL-1 and BCL-2 may provide an alternative therapeutic approach in BCL, however optimal patient selection will remain the key to obtaining high response rates and tolerability.

1, 2 Treatment of CLL cells with entospletinib, but not other BCR-signaling inhibitors, led to a disruption of BAFF-BCR cross-talk and downmodulation of MCL1 mRNA and protein, thus implicating SYK in transduction of multiple pro-survival signals emanating from the tumor microenvironment.1 Entospletinib has shown promising clinical activity in CLL, alone or in combination with obinutuzumab, including in patients with high-risk disease such as TP53 aberrant.3, 4 The drug is very well tolerated, however its development in CLL has been halted. Meanwhile, we have shown that luxeptinib, a dual SYK/BTK kinase inhibitor, has activity in BTK inhibitor-resistant lymphoid models in vitro.5 Luxeptinib is now being investigated in lcinical trials in hematologic malignancies...The early results of MS-553, a selective PKC-β inhibitor, indicates that this agent is tolerable and effective both as single agent and in combination with venetoclax.8 Proteolysis-targeting chimeras (PROTACs) are a new class of small molecules with two covalently-linked ligands recruiting target protein and E3 ubiquitin ligase together to trigger and enable proteasomal degradation of the target protein.9 “BTK degraders”, such as NRX- 2127 (Nurix Therapeutics) and BGB-16673 (Beigene), have entered clinical trials in patients with lymphoid malignancies...Additionally, NX-2127 has shown preclinical activity similar to immunomodulatory drugs (IMiDs) by catalyzing the ubiquitination of Ikaros (IKZF1) and Aiolos (IKZF3), resulting in increased T-cell activation.10 Early results of an ongoing clinical trial of NX-2127 demonstrate an ORR of 33% in heavily pre-treated patients with CLL, and overall good tolerability 11...The preclinical activity of AZD5991 has shown that selective targeting of MCL1 induced metabolic dysfunction and abrogated survival of diffuse large B cell lymphoma and ibrutinib-resistant mantle cell lymphoma cell lines in vivo and in vitro.13 Other BH3-mimetics targeting MCL1 include AMG176 and S63845.14-16 In an experimental design testing the effects of AMG-176 on CLL and normal hematopoietic cell death it was demonstrated that AMG-176 is an active agent in inducing CLL cell death while sparing normal blood cells...Anti-CD20 monoclonal antibodies – rituximab, obinutuzumab and ofatumumab – have significantly improved the survival outcomes. The B cell activating factor receptor (BAFF-R) is one of the main pro-survival receptors in B cells.18 In a preclinical study, ianalumab (VAY-736), a humanized defucosylated engineered antibody directed against BAFF-R, antagonized pro-survival effects of BAFF in CLL cells and showed promising activity both as a single agent and in combination with ibrutinib.19 A phase 1 study of dose escalation and dose expansion investigated the combination of ianalumab with ibrutinib in 32 patients with CLL with median one prior line of therapy (range, 0-4)...This study showed promising results not expected with ibrutinib alone.20 Tafasitamab – a Fc-enhanced, humanized, monoclonal antibody to CD19 – in combination with idelalisib or venetoclax in 24 patients has been associated with an ORR of 77% and 91%, respectively...In a phase 1 study involving 26 patients with R/R CLL, cirmtuzumab administered at four biweekly infusions was shown to have a long plasma half-life and did not have dose-limiting toxicity, potentially providing another treatment opportunity for patients with CLL.22 Immune Cell Enabling Therapies...A recent report of a phase 1/2 study of lisocabtagene maraleucel, an autologous CD19-directed CAR T-cell therapy (TRANSCEND CLL 004), confirmed efficacy in patients with R/R CLL.23 In this study, 23 patients with median 4 prior lines of therapy (range 2-11) were enrolled, 10 of whom were considered double exposed/refractory...In total, 65% of patients required administration of tocilizumab and/or corticosteroids.23 In addition to the ongoing phase 2 portion of this study, efforts now focus on innovative CAR T-cell designs as well as combination strategies...A phase 1b/2 ongoing trial is currently examining the safety and tolerability of the product in patients with R/R CLL. The early results suggest that epcoritamab administered subcutaneously is well tolerated in a heavily pretreated patient population with multiple high-risk features and shows clinical activity.25 Furthermore, an ongoing study is demonstrating preliminary efficacy of epcoritamab in patients with Richters transformation, a notoriously difficult-to-treat complication of CLL.26

Despite being previously considered undruggable, seven small-molecule Mcl-1 inhibitors have recently entered clinical trials. Here, we report the crystal structure of the clinical-stage inhibitor AMG-176 bound to Mcl-1 and analyze its interaction along with clinical inhibitors AZD5991 and S64315...Nuclear Magnetic Resonance (NMR)-based free ligand conformer analysis demonstrates that such unprecedented induced fit is uniquely achieved by designing highly rigid inhibitors, preorganized in their bioactive conformation. By elucidating key chemistry design principles, this work provides a roadmap for targeting the largely untapped PPI class more successfully.

The response to either BCL-2 (venetoclax) or MCL-1 (AMG176) inhibition was BAX-dependent and much reduced in TP53-mutant compared to TP53-WT cells, while the combination of two BH3 mimetics effectively activated BAX, circumventing survival mechanisms in cells treated with either BH3 mimetic, and synergistically induced cell death in TP53-mutant AML and stem/progenitor cells. Our results demonstrate that co-targeting BCL-2 and MCL-1 overcomes BAX deficiency-mediated resistance to individual BH3 mimetics in TP53-mutant cells, thus shifting cell fate from survival to death in TP53-deficient and -mutant AML. This concept warrants clinical evaluation.

Furthermore, increases in human T cell viability, proliferation, and function as facilitated by AMG-176 could offer insight into the advancement of effector cell-based therapies, such as chimeric antigen receptor (CAR) therapy. We may employ AMG-176 alongside CAR T therapy in order to achieve more effective clinical outcomes.

PK data suggest that AMG 176 systemic exposures in NSG mice may not be sufficient to elicit meaningful and prolonged regressions in pediatric ALL PDXs. (Supported by NCI Grants CA199000 and CA199222)

We conclude that MCL-1i blocked Mcl-1 ubiquitination via enhanced deubiquitination and dissociation of Mcl-1 from Noxa, Bak and Bax, and Mule de-stabilization. These are critical events associated with increased Mcl-1 protein stability with AMG-176 and AZD5991.

The subsequent key areas hold promise: Alternative Inhibitors of BTK Here, non-covalent BTK inhibitors, such as pirtobrutinib (LOXO- 305) and nemtabrutinib (ARQ-531), have shown effi cacy in CLL resistant to covalent BTK inhibitors...AZD5991 is a highly selective BH3-mimetic that demonstrates high potency in MCL1-dependent cell lines.9 Our group has shown that selective targeting Mcl-1 induced metabolic dysfunction and abrogated survival of lymphoid cells in vitro and in vivo.10 Other BH3- mimetics targeting Mcl-1 include AMG-176 and S63845.11,12 However, Mcl-1 targeting agents may be associated with toxicities, including against the hematopoietic stem and progenitor cells, potentially leading to cytopenias in the clinic.13 The therapeutic window for these agents needs to be defi ned. BH3-mimetics which target Bcl-xL, such as navitoclax, are not being developed in CLL due to concerns of thrombocytopenia.14 However, AZD4320, an alternative Bcl-2/xL inhibitor, is being studied in lymphoid malignancies as an intravenous formulation, with hope to mitigate its effect on platelets.15 Therapeutic Antibodies Targeting surface receptors and inducing both direct and immunemediated apoptosis has been a success story in CLL with use of anti-CD20 agents...Lanalumab (VAY-736), a humanized defucosylated engineered antibody directed against BAFF-R, antagonized pro-survival effects of BAFF in CLL cells.16 In a phase 1 study in combination with ibrutinib in 32 patients with CLL, CR was achieved in 38% of patients, and 42% demonstrated undetectable minimal residual disease (uMRD) in the blood/bone marrow, a promising result not expected with ibrutinib alone.17 Alternative targets for therapeutic antibodies include ROR1 (cirmtuzumab) and CD19 (tafasitamab)...A recent report of a phase 1/2 study of lisocabtagene maraleucel, an autologous CD19-directed CAR T-cell therapy (TRANSCEND CLL 004), confi rmed effi cacy in patients with relapsed/refractory CLL.18 In this study, patients had a median of 4 prior therapies, including ibrutinib and venetoclax...In a Phase 1/2 trial, HLA-mismatched CD19-targeting CAR NK cells induced CRs in patients with CLL after a single infusion and without CRS or neurotoxicity attributable to the cellular product.19 Finally, bi-specifi c antibodies have demonstrated impressive effi cacy in non-Hodgkin lymphoma and are also an off-the-shelf product which boasts high tolerability. Development of bi-specifi c antibodies in CLL is still in early stages, however epcoritamab (a subcutaneously administered CD3xCD20 Duobody) demonstrated responses in an ongoing Phase 1 study.20 In sum, targeted therapy replaced chemo-immunotherapy in treatment of CLL, and emerging small molecule and cell therapy approaches auger an expansion of the therapeutic armamentarium for CLL in the next decade.

P1, N=175, Recruiting, Amgen | Suspended --> Recruiting | Trial completion date: Jun 2024 --> Nov 2024

Synthetic inhibitors targeting these proteins have been developed, and some hematological malignancies are now widely treated with a BCL-2 inhibitor (venetoclax)...Six MCL-1 inhibitors (S64315, AZD-5991, AMG-176, AMG-397, ABBV-467 and PRT1419) have been evaluated in clinical trials since 2016, but some were affected by safety issues and none are currently used clinically...Importantly, a similar treatment with NA1-115-7 was not toxic to erythrocytes, peripheral blood mononuclear cells, platelets, or cardiomyocytes. These results highlight the potential of natural products for use as specific BH3 mimetics non-toxic to normal cells, and they suggest that NA1-115-7 may be a promising tool for use in cancer treatment.

Especially, hydnocarpin (-8.9 kcal/mol) and yadanzioside P (-9.4 kcal/mol) exhibited lower binding energy than approved drugs AMG176 (-8.6 kcal/mol) and gilteritinib (-9.1 kcal/mol) to receptors MCL1 and FLT3 respectively, indicating their potential to be lead molecules. Therefore, this study concludes that combination of empirical knowledge, in silico molecular docking and ADMET profiling is useful to find natural product-based drug candidates. This technique can be applied to other natural products with known empirical efficacy.

P1, N=175, Suspended, Amgen | Recruiting --> Suspended

Interferon (IFN)-γ induces IDO1 expression through the Jak/STAT1 pathway and mediates Kyn production concomitantly with Trp consumption in CLL-conditioned media, while INCB018424 (ruxolitinib), a JAK1/2 inhibitor, impaired both effects...Moreover, Kyn-treated CLL cells are less affected by the pro-apoptotic effect of ABT-199 (venetoclax), while CH-223191 showed synergistic/additive cytotoxicity with this drug. Lastly, targeting directly MCL1 in CLL cells with AMG-176, we abrogate the pro-survival effect of Kyn. In conclusion, our data identify IDO1/Kyn/AHR signaling as a new therapeutic target for CLL, describing for the first time its role in CLL pathobiology.

Proapoptotic proteins decreased during therapy. Collectively, these data provide a rationale to test Mcl-1 antagonists alone or in combination in CLL during treatment with ibrutinib and venetoclax.

Selectively inhibiting PRMT5 has shown significant anti-tumor activity in preclinical MCL models, and a Phase 1 clinical trial with PRT543 (Prelude), a novel PRMT5 inhibitor, is underway...BH3 mimetics navitoclax (BCL2, BCLXL, and BCLw inhibitor), A852 (BCLXL inhibitor), and AMG176 (MCL1 inhibitor) were found to have IC50s below 1uM in five, two, and four of the nine cell lines respectively...iBH3 flow-based analysis revealed increased sensitivity of ex vivo PDX cells to pan BCL2, BCLXL, and MCL1 inhibition. These results provide rationale for combining BH3 mimetics and PRMT5 inhibition in clinical trials as a novel treatment strategy for MCL.

We screened a panel of KRAS-mutant NSCLC cell lines as well as patient-derived xenograft (PDX) mouse models and observed that loss of the tumor suppressor STK11/LKB1 is associated with increased sensitivity to combined MAPK (either the KRAS G12C inhibitor sotorasib or MEK inhibitor trametinib) and MCL-1 inhibition (AMG 176). Consistent with this mechanism, ex vivo treatment of tumor tissue from a KRAS-LKB1 mutant NSCLC patient with sotorasib or trametinib increased MCL-1 dependent priming. These results reveal a novel link between LKB1 and the regulation of BCL-2 family proteins and provide preclinical rationale for evaluation of combined KRAS G12C + MCL-1 inhibitors for KRAS-LKB1 mutant NSCLC.

We tested venetoclax in trisomy 12 CLL cells either silenced or not for Notch2 expression or in combination with an inhibitor of Mcl-1, AMG-176. The expression of Notch2 identifies a subset of CLL patients, mainly harboring trisomy 12, characterized by high levels of Mcl-1. This biological mechanism may compromise an effective response to venetoclax.

P1, N=175, Recruiting, Amgen | N=127 --> 175

In AML, venetoclax is combined with the epigenetic modifier 5-azacytidine...The BH3 profiling was correlated to the response of the cell lines to a series of BH3 mimetics : venetoclax (selective BCL-2 inhibitor), ABT-263 (BCL-2, BCL-XL and BCL-W inhibitor), WEHI-539 (BCL-XL inhibitor) and AMG-176 (MCL-1 inhibitor)...BH3 profiling is a powerful tool to identify the anti-apoptotic dependence in MM cell lines and MM patient samples, which we can exploit pharmacologically to kill MM cells in a personalised medicine approach. Combining epigenetic modifiers with venetoclax induces BCL-2 dependence in MM and enhances response to treatment.

This is due primarily to limited responses to available therapies including the highly promising FDA-approved combination of Bcl-2 inhibition by venetoclax (VEN) with hypomethylating agents (DiNardo CD et al., Blood 2020), which resulted in CR/CRi rates of 70-95% and good tolerability in elderly patients (DiNardo CD et al., Lancet Oncol 2018 and Blood 2019)...The Bax KD cells were resistant to VEN and AMG 176, while the combination of the two agents synergistically induced cell death...Thus, targeting Bcl-2 or Mcl-1 individually is insufficient and inhibition of both proteins is needed to shift cell fate from survival to death and circumvents resistance of TP53 deficient/mutant AML and AML stem/progenitor cells to BH3 mimetics. The concept warrants further clinical evaluation.

P1, N=127, Recruiting, Amgen | Trial completion date: Dec 2023 --> Jun 2024 | Trial primary completion date: Dec 2023 --> Jun 2023

AZD5991 is a highly selective BH3-mimetic that demonstrates high in vitro potency in MCL1-dependent cell lines with an IC50 <1 nM.7 We have demonstrated that direct MCL1 inhibition with AZD5991 disrupts survival of neoplastic B-cells in lymph-node mimicking conditions, induces mitochondrial dysfunction and cooperates with BCL2/X inhibitors in vitro and in vivo.8 A phase 1 clinical trial of AZD5991 alone or in combination with venetoclax in hematologic malignancies is ongoing (NCT03218683)...AMG-176 demonstrated synergy with venetoclax in AML models; however, it also caused cytopenias.9 AMG-176 was shown to induce apoptosis of CLL cells independent of prognostic markers and overcame the protective effect of stromal microenvironment.10 However, suppressive effects on hematopoiesis will likely become the dose- limiting factor in clinical trials of MCL1-targeting agents. The effect of MCL1 inhibition on cord blood-derived CD34+ cells was studied using a small-molecule inhibitor, S63845,11 resulting in almost complete depletion of human hematopoietic stem and progenitor cells, while mature blood cells survived normally...We have shown that SYK inhibition with entospletinib leads to downmodulation of MCL1 protein in CLL both in vitro and in the clinic.12,13 Treatment of CLL cells with entospletinib, but not other BCR-signaling inhibitors, led to a disruption of BAFF-BCR cross-talk and downmodulation of MCL1 mRNA and protein, thus implicating SYK in transduction of multiple pro-survival signals emanating from the tumor microenvironment.13 Entospletinib has shown promising clinical activity in CLL.12,14 It is currently being developed in myeloid malignancies.15 A novel dual SYK/BTK inhibitor luxeptinib also was shown to downregulate MCL1 and other pro-survival BCL2 proteins in CLL.16 Transcriptional cyclin-dependent kinases (CDK7/9) regulate activity of RNA polymerase, thereby controlling production of mRNA. Downmodulation of MCL1 has been considered a key mechanistic event accounting for the pro-apoptotic activity of CDK inhibitors in neoplastic B-cells.17,18 Pan-CDK inhibitors (flavopiridol, dinaciclib) demonstrate clinical efficacy in lymphoid malignancies. We and others reported that preclinical efficacy of AZ5576, a selective inhibitor of CDK9, and its clinical congener AZD4573 in lymphoid tumors depended on rapid downmodulation of MCL1, BFL1, and MYC.19–21 CDK9 inhibition can increase efficacy of BH3-mimetics, but safety of this combination will need to be explored.22,23 CDK9 inhibitors in development, in addition to AZD4573, include VIP152, CYC065, and voruciclib...Navitoclax is a small-molecule inhibitor of BCL2, BCLX, and BCL2L2; however, its use in CLL has been plagued by thrombocytopenia.24 AZD4320 is an alternative agent that co-targets BCL2/X...ABBV-155, an antibody-drug conjugate targeting BCLX, where BCLX is being used as a payload to avoid “off-tumor” effects, demonstrated promise in solid tumor models.26 Finally, as many microenvironment-driven pro-survival pathways converge on NFB, leading to induction of chemokines, cell cycle regulators, and BCL2 family proteins themselves, this transcription factor continues to be an attractive target in CLL...When combined with ibrutinib in murine CLL models, VAY-736 produced prolonged survival compared with either therapy alone.28 Alternative targets for therapeutic antibodies include ROR1 (cirmtuzumab), CD19 (tafasitamab), and others.29 As resistance to novel agents is becoming an unmet need in CLL, exploration of novel targets is of paramount importance...Multiple CDK inhibitors are currently being explored and have anti-tumor effects not restricted to MCL1 inhibition. CAR T cells and bi-specific antibodies have exceptional efficacy in lymphoid malignancies and thus are of high relevance in CLL.

However, 10–50% of newly diagnosed patients with AML may not respond to venetoclax and HMA or LDAC, and 3–15% patients may not respond to venetoclax with intensive or non-intensive chemotherapy.1–6 In addition, up to 40% of responding patients may relapse with low rates of response of 20% to salvage therapy and poor overall survival of 2 months after relapse.7 Clinical and biological factors associated with primary and acquired resistance to venetoclax include secondary AML, monocytic differentiation, complex cytogenetics, mutations in TP53, BAX, dependence on other anti- apoptotic proteins, altered metabolism of nicotinamide, fatty acids, and oxidative phosphortylation.3,8–14 Several novel inhibitors of BCL-2 are currently being tested in clinic, including BGB 11417, APG-2575, LP-108 and others...There is strong pre-clinical rationale for targeting MCL-1 alone as well as in conjunction with BCL-2 inhibition in AML.15 Recently several selective and highly potent MCL-1 inhibitors have entered pre-clinical and clinical development including S63845, AZD5991, AMG397, and others. Questions remain regarding the therapeutic window of these inhibitors given the important physiologic role of MCL-1 in vital organs and early reports of cardiac adverse events from the AMG176 phase 1 trial.15,16 Multiple pre-clinical studies have expectedly shown synergism between BCL- 2 and MCL-1 inhibition making it a promising path for clinical development of these agents.17,18 Multifactorial challenges in design of specific MCL-1 inhibitors also led to interest in compounds which downregulate MCL-1 expression. Cyclin dependent kinase (CDK) inhibitors including alvocidib, dinaciclib, voruciclib are in various stages of evaluation. Although addition of alvocidib to intensive chemotherapy improved response rates but failed to improve event-free or overall survival.19 Novel CDK inhibitors are currently in early phase trials including AZD4573, CYC065, TG02-101, and others. Inhibition of Nedd8 activating enzyme has complex repercussions for the intrinsic apoptotic pathway with eventual increase in Noxa leading to MCL-1 neutralization.20 Pevonedistat has shown promising early results in AML and myelodysplastic syndrome and is being investigated multiple clinical trials for solid tumors as well. BCL-xL Inhibition Another anti-apoptotic protein BCL-xL had been long recognized as a potential therapeutic target in AML, in particular AML from preceding MPN and AML recurrent post venetoclax failure, but toxicity of earlier inhibitors precluded clinical development.21–23 Recently, AZD0466, a dual BCL-2/xL inhibitor with a favorable therapeutic index and robust activity has been developed and is undergoing pre-clinical development and planned for phase iin hematological malignancies.24 Targeting the Extrinsic Apoptosis Pathway Inhibitor of apoptosis protein (IAP) inhibition: X-linked IAP (XIAP), cellular IAP (cIAP) and survivin have been of long- standing interest in AML. Prior clinical trials with XIAP inhibitor AEG35156, cIAP targeting agent birinapant, and survivin targeting agent LY2181308 have not succeeded in clinc.16,25 ASTX660 is a dual antagonist of XIAP and cIAP which is currently being investigated in phase 1/2 trials in solid tumors and in combination with HMA in relapsed or refractory AML.26,27 TRAIL Agonism Agonists of the TNF-related apoptosis-inducing ligand (TRAIL) receptors have been tested in AML with low response rates.28,29 Previous agents have had limited success in part due to suboptimal clustering of TRAIL receptors.30 Novel antibodies against TRAILR1 and TRAILR2 including an IgM molecule IGM-8444, a tetravalent compound INBRX-109, and HLX56 are currently in phase 1 trials and preclinical data suggests potential synergy with venetoclax.31 FLIP Inhibition FLICE-like inhibitor protein (FLIP or CFLAR) is a key regulator of the death-inducing signaling complex (DISC) involved in the extrinsic apoptotic pathway...This can be augmented by inhibiting p53 degradation via MDM2, which is often upregulated in AML.34 Idasanutlin in combination with venetoclax showed anti- Figure 1 leukemic activity in the dose finding stage in R/R AML.35 Several other inhibitors of MDM2 and dual MDM2/X inhibitors are currently in various stages of pre-clinical and clinical development including HDM-201, KRT-232, BI-9078282, and others.34 Conclusions Opportunities to target the apoptosis machinery in AML has considerably evolved in the last decade. While venetoclax heralded a paradigm shift for patients, we are now faced with challenges in patients who relapse or remain refractory. We have novel clinical stage compounds to methodologically target different facets of the apoptotic pathway and optimize novel combinations with the goal to improve the cure rates in AML patients.

We screened a panel of BH3 mimetics in MM cells and patient bone marrow samples; ABT-199 (selective BCL-2 inhibitor), ABT-263 (BCL-2, BCL-xL and BCL-W inhibitor), WEHI-539 (BCL-XL inhibitor) and AMG-176 (selective MCL-1 inhibitor). Furthermore, we confirmed enhanced cell death by Annexin V/PI staining following both ABT-199 and the two classes of epigenetic drugs in two patient MM samples ex-vivo. Future work will focus on determining the mechanism of enhanced cell death induced by the epigenetic drugs to improve the response to ABT-199 treatment.

P1, N=127, Recruiting, Amgen | Trial primary completion date: Aug 2022 --> Nov 2023

No significant difference in body weight was found between groups. Our results show that AMG 176 plus gilteritinib treatment was effective and well tolerated in mouse models of AML, which supports further evaluation in a clinical setting.

In chronic lymphocytic leukaemia, the pro-survival protein BCL2 is highly expressed and inhibiting BCL2 with a selective small molecule inhibitor venetoclax has proven to be highly effective...Unlike S63845 and its chemical analogs, the action of AMG-176, a distinct MCL1i, was not affected by overexpressing MDR1. Amongst the other BH3-mimetics we tested, the action of the BCL2 inhibitor S55746 was also compromised by MDR1 overexpression.Taken together, our findings suggest that MDR1 overactivity could potentially pose a barrier to the clinical efficacy of distinct classes of BH3-mimetics that target MCL1 (S63845 and its relatives) and BCL2 (S55746 and compounds of the same class). We conclude that other inhibitors of MCL1 or BCL2 should be considered in cancers with MDR1 overexpression.

We investigated combined inhibition of BCL-2 and MCL-1 in AML cells resistant to apoptotic stimuli through various mechanisms and demonstrate that co-inhibition of BCL-2 with VEN and MCL-1 with AMG176 synergistically targets AML cells that exhibit intrinsic or acquired resistance to BH3 mimetics in vitro and in vivo. In conclusion, we demonstrate the alteration of multiple BCL-2 family proteins contributes to BH3 mimetic resistance that can be overcome by combined inhibition of MCL-1 and BCL-2. The striking effectiveness of co-targeting BCL-2 and MCL-1 in AML resistance to a BH3 mimetic via various mechanisms or to VEN/HMA suggests broad clinical applications of this strategy, and warrants clinical evaluations.

In this review, we summarize the recent literature on small molecule and peptide inhibitors of Mcl-1, which are divided into different types including: peptide inhibitors, gossypol derivatives, marinopyrrole derivatives, S1 derivatives, indole derivatives, quinoline derivatives, S63845, AZD5991, AMG176, etc. Their biological activities are also summarized. Mcl-1 is a valid drug target and inhibition of Mcl-1 with a small molecule inhibitor is a promising strategy for cancer therapy.

P1, N=119, Recruiting, Amgen | Active, not recruiting --> Recruiting | N=65 --> 119 | Trial completion date: Jan 2022 --> Oct 2023 | Trial primary completion date: Jan 2022 --> Sep 2022