AZD4320

BCL-2 inhibition by venetoclax (VEN) is beneficial in many patients (pts) with acute myeloid leukemia (AML), but resistance is common due to upregulation of other pro-survival proteins such as BCL-extra-large (BCL-xL) and myeloid cell leukemia-1...Preclinically, AZD4320 showed greater inhibition of tumor growth than VEN and navitoclax in VEN-resistant xenograft models (Balachander et al... Given the observed DLTs of asymptomatic increase in troponin levels, and the lack of significant clinical benefit, the study was terminated.

Venetoclax is a selective BCL-2 inhibitor and is successfully used in CLL and AML, but heterogeneous sensitivity to venetoclax has been described in ALL and inhibitors of other BCL-2 family members including BCL-XL-selective A-1331852 and MCL-1 selective AZD5991 have been developed. Moreover, a dual inhibitor of the anti-apoptotic BCL-2 family members BCL-2 and BCL-XL (AZD4320) with its dendrimer conjugate (AZD0466) has recently shown anti-tumor activity in hematologic cancer models with manageable toxicity...Taken together, we found vulnerabilities of T-ALL to BCL-2 family inhibition, particularly to dual BCL-2/BCL-XL inhibition by AZD4320, and we demonstrated on-target activities. Using BH3-profiling, we identified BAD-priming as a marker of response for AZD4320 and MCL-1 dependence as a resistance mechanism that can be targeted by combination treatment, suggesting further clinical evaluation.

To evaluate if combination treatment of AZD0466 with BTK inhibitors would improve efficacy, we transplanted murine Eµ-TCL1 tumors into syngeneic recipient mice and randomized them for treatment with vehicle, ibrutinib (30mg/kg in drinking water), acalabrutinib (25mg/kg, p.o. QD), AZD0466 (70mg/kg, i.v., QW) and combination of AZD0466 with ibrutinib or acalabrutinib. Moreover, AZD4320 was highly efficacious in MAVER-1 and MINO cell line models where resistance to venetoclax mediated by BCL-XL upregulation was modelled by an in vitro dose escalation method. In summary, our pre-clinical study shows that the dual BCL2/BCL-XL inhibitor could represent an important treatment option for venetoclax resistance mediated by specific BCL2 mutations or BCL-XL upregulation and that its efficacy could be further improved upon combination treatment with BTKi.

Background: The BCL2 family of proteins induce apoptosis via caspase activation and are being increasingly targeted in hematologic malignancies by small molecules such as venetoclax (VEN)...Preclinically, AZD4320 showed activity in patient (pt)-derived AML xenografts and superior tumor growth inhibition to VEN and navitoclax in VEN-resistant xenograft models (Balachander et al...Module 2 investigates drug-drug interactions between AZD0466 and voriconazole... Treatment with AZD0466 is well tolerated in pts with R/R acute leukemia, with AEs matching expected toxicity from preclinical data. Preclinical efficacy modeling and clinical PK data suggest further dose escalation is warranted to explore clinical activity.

In a selection of 166 compounds we showed that inhibitors of ATR and WEE1 were cytotoxic against a panel of OCCC cell lines. These two drugs are already in other clinical trials, making them ideal candidates for treatment of OCCC.

The active moiety, AZD4320, is a potent dual inhibitor of BCL-2 and BCL-XL...AZD0466 outperformed the selective BCL-2 inhibitor venetoclax in 6/10 models. Notably, AZD0466 was active in models resistant to platinum/etoposide chemotherapy, the standard-of-care for SCLC...AZD0466 exhibits linear PK, consistent across solid tumor and leukemia patients. The doses tested are in line with preclinical studies in SCLC.

Specific Bcl-2 inhibition using venetoclax is beneficial in patients with acute myeloid leukemia (AML), but resistance often develops due to upregulation of anti-apoptotic proteins such as Bcl-xL and Mcl-1...Following IV infusion, released AZD4320 exhibited a dose-proportional increase in area under the concentration time curve (AUC) and maximum serum concentration (Cmax), moderate PK variability (≈50% coefficient of variation), and a half-life of ≈18 hours. AZD0466 has been well tolerated, with no DLTs to date and no discontinuations due to treatment-related AEs. The trial continues to enroll, further dose escalation is planned, and updated data will be presented.

Mantle cell lymphoma (MCL) is a rare chronically relapsing subtype of aggressive B-cell non-Hodgkin lymphoma characterized by the canonical chromosomal translocation t (11; 14) and other molecular cytogenetic aberrations including overexpression of BCL2 protein. We demonstrated that the thrombocytopenia associated with continued therapy with A1155463 could be managed by 4 days on / 3 days off treatment strategy, which cannot be applied in case of fixed dual BCL2/BCL-XL inhibitors like navitoclax, or AZD4320. In summary, the combined inhibition of BCL2 and BCL-XL with VEN and A1155463 is a highly effective experimental treatment strategy for R/R MCL with a potential translation to the clinical grounds.

To investigate the in vitro, ex vivo and in vivo effects of AZD5991 (AstraZeneca), a novel MCL1 inhibitor compound, alone or in combination with AZD4320 (BCL-2/BCL-XL inhibitor compound), venetoclax, cytarabine and doxorubicin. MCL1 overexpression in mononuclear cells from patients with acute leukemia and that present or not resistance to venetoclax treatment, is associated with poor prognosis and relapse disease. Our results demonstrated that co-targeting MCL-1, BCL-2 and BCL-xL, through the AZD5991 and AZD4320 compounds in the treatment of acute leukemias, may enhance therapeutic specificity, overcome chemoresistance and contribute with the cure of these aggressive malignant disorders.

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.

AZD4320 was developed as a dual inhibitor of BCL-2 and BCL-XL, and its dendrimer conjugate (AZD0466) was recently reported to demonstrate anti-tumor activity in hematological cancer models, while showing only a transient thrombocytopenia. Aims In this study, the anti-leukemia activities of the dual BCL-2 and BCL-XL inhibitor AZD4320 and of MCL-1-selective AZD5991 were evaluated and compared to the effects of other BH3-mimetics (BCL-2-selective venetoclax, BCL-XL-selective A-1331852 and MCL-1-selective S63845)...Importantly, the highest synergism was found at low concentrations of both inhibitors, suggesting efficacy at moderate concentrations, which could potentially be achieved in vivo . Conclusion In summary, our study demonstrates sensitivity, on-target activity and synergism of the dual BCL-2 and BCL-XL inhibitor AZD4320 with inhibition of MCL-1, thereby providing strong evidence for further clinical evaluation in ALL.

Several compounds targeting BCL-2 signaling, which are under clinical investigation, were tested (BCL-2: venetoclax, BCL-2/Xl: AZD4320, MCL-1: AZD5991 and CDK9: AZD4573)...Priming with a hypomethylating agent (HMA, decitabine) resulted in additive (CI close to 1) to synergistic (CI 0.25 – 0.7) proapoptotic effects in isobologram analysis and led to a release of drug resistance in primary resistant cell lines...attenuation thereof after forcely expressing the dominant-negative splicing variant). To summarize, we show that inhibition of BCL-2 signaling is a promising approach to target acute leukemia – as a monoagent as well as in combination with HMA: Further, we provide a path for exploration of ASPP2k as a predictive tool as well as a therapeutic sensitizer of pro-apoptotic drugs, which will be addressed in future studies.

Dual BCL2/xL inhibition with AZD4320 has potential for broader activity than BCL2-specific inhibition with venetoclax (Balachander et al, Clinical Cancer Research 2020)...Treatment with hydroxyurea during screening and cycle 1 is permitted to control white blood cell count...Module 2 is a drug-drug interaction (DDI) study that will investigate the safety and establish the sensitivity of AZD0466 to voriconazole, a strong inhibitor of CYP3A4...This study is actively enrolling patients at sites in the USA, and will be opening at multiple sites in Australia, Europe and South Korea. An update of preliminary safety and pharmacokinetics will be presented.

This is largely due to frequent relapses after therapies including paradigm shifting therapies BTK inhibitors (BTKi), such as ibrutinib and acalabrutinib, and Bcl-2 inhibitor (Bcl-2i) venetoclax after long-term treatment in the clinic. Conclusion Compared to AZD4320/AZD0466 and acalabrutinib, combination therapy demonstrated anti-MCL synergy both in vitro and in vivo . These findings suggest that targeting Bcl-2/X L and BTK is promising to overcome multiple acquired resistance phenotypes, including CD19 CAR T-cell therapy.

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.

Malignant pleural mesothelioma (MPM) is an aggressive cancer with treatment limited to Cisplatin and Pemetrexed chemotherapy...In this study we show another inhibitor, AZD4320 that targets BCL-XL (and BCL-2), can also potently kill MPM tumor cells in vitro (EC values in the 200 nM range) and this effect is enhanced by co-inhibition of MCL-1 using AZD5991...Critically, the degree of thrombocytopenia, an on-target toxicity associated with BCL-XL inhibition, was significantly reduced throughout the treatment period compared to other BCL-XL-targeting BH3-mimetics. These pre-clinical findings provide a rationale for the future clinical evaluation for novel BH3-mimetic formulations in MPM, and indeed, other solid tumor types dependent on BCL-XL.

Co-treatment of DLBCL cells with Bcl-2/xL inhibitors AZD4320, venetoclax and navitoclax overcame resistance to AZD5991. Mcl-1 inhibition leads to mitochondrial dysfunction and inhibition of cellular respiration. Resistance to Mcl-1 inhibition may be overcome by concurrent targeting of alternative anti-apoptotic proteins (Bcl-2/xL) in NHL.

The optimised candidate is shown to be efficacious and better tolerated in preclinical models compared with AZD4320 alone. The AZD4320-dendrimer conjugate (AZD0466) identified, through mathematical modelling, has resulted in an improved therapeutic index and thus enabled progression of this promising dual Bcl-2/Bcl-x inhibitor into clinical development.

AZD0466, the nanomedicine formulation of AZD4320 (30mg/kg, weekly, IV), dramatically inhibited tumor growth and prolonged mouse survival in an ibrutinib-CAR-T dual-resistant PDX mouse model. The novel BCL-2/XL dual inhibitor AZD4320 demonstrated excellent anti-MCL activity in both ibrutinib/venetoclax-sensitive and -resistant MCL cells in vitro. This was further validated in vivo in a ibrutinib-CAR-T dual-resistant PDX model. These findings provide evidence that dual targeting of BCL-2 and BCL-XL by AZD4320 is promising as it may overcome therapeutic resistance in relapsed/refractory MCL.

While targeting BTK (ibrutinib, acalabrutinib) and PI3K (idelalisib, duvelisib) has shown efficacy in CLL, clinical responses fall short in aggressive NHL, necessitating the development of novel approaches to suppress BCR signaling...Consistent with the above observations, synergy was observed between CG-806 and inhibitors of metabolic enzymes (teleglenastat, perhexiline maleate) and BH3-mimetics targeting BCL2/X proteins (venetoclax, AZD4320)...BCL2 family proteins may be implicated in resistance to CG-806. These results provide rationale for further investigation of CG-806 in aggressive NHL.

This concept has been successfully applied to hematological malignancies, with the recent approval of venetoclax, a BCL2 inhibitor, for the treatment of chronic lymphocytic leukemia and acute myeloid leukemia.Solid tumors have instead proven very refractory to these approaches, and the clinical activity of BH3 mimetics is extremely limited.To determine the effect of targeting key anti-apoptotic proteins that protect ATC cells from apoptosis, we have studied the response of a large panel of ATC cell lines to novel MCL1 (AZD5991) and BCL-2/BCL-XL (AZD4320) inhibitors.We found that every cell line tested was modestly sensitive to each inhibitor in monotherapy, and that the AZD5991 and AZD4320 showed identical or quite similar EC50s in the low micromolar range. This notion, however, cannot be readily translated into a therapeutic opportunity because concomitant treatment at doses that exhibit monotherapy activity results in rapid lethal toxicity.To begin exploring how to mitigate this toxicity, we hypothesized that inhibition of one critical anti-apoptotic protein (i.e. BCL-XL), in co-addicted cells, might shift the cells’ dependence on the other protein (i.e. MCL1). Thus, we have tested whether intermittent and sequential dosing in vitro could improve efficacy compared to monotherapy, providing an opportunity for a therapeutic margin.Strikingly, pre-treatment with a dose of the BCL-2/BCL-XL inhibitor that has no effect in monotherapy resulted in an approximately 50-fold decrease in EC50 for the MCL1 inhibitor, and in massive caspase 3-mediated apoptosis occurring within 6-8 hours from MCL1 inhibition.These results provide a compelling proof-of-principle suggesting that ATC cells can be effectively killed using a rationally designed drug administration strategy that targets critical components of the cells’ antiapoptotic machinery.

AZD0466 is a novel drug-dendrimer conjugate, where the active moiety, AZD4320, is chemically conjugated to Starpharma’s DEP® dendrimer platform, a 5-generation PEGylated poly-lysine dendrimer via a hydrolytically labile linker...AZD0466 demonstrated greater monotherapy activity than platinum/etoposide chemotherapy regimen or venetoclax monotherapy in 6 out of 11 SCLC PDX models...In the SUDHL-4 GCB DLBCL model, 103 mg/kg AZD0466 with 10 mg/kg Rituximab resulted in complete and durable regressions in 5/6 animals. Finally, combination of 103 mg/kg AZD0466 with 12.5 mg/kg BID Acalabrutinib, a Bruton’s Tyrosine kinase inhibitor, was investigated in OCI-LY10 DLBCL model...These data show that AZD0466 has monotherapy activity and a differentiated response from Venetoclax in SCLC models. AZD0466 also has therapeutic potential as monotherapy and a combinatorial agent to increase the depth and duration of response to standard of care and BTK inhibitors in hematological tumors.

In this study, we tested BCL-2 and BCL-XL dependencies among different subtypes of ALL and the potential to revert these using AZD0466, a novel drug-dendrimer conjugate, of a BCL-2/ BCL-XL inhibitor AZD4320 and an FDA-approved BCL-2 inhibitor, ABT-199 (Venetoclax). Our findings suggest that the novel dual BCL-2/BCL-XL inhibitor AZD0466 outperforms single BCL-2 inhibition by ABT-199 in T-ALL and Ph-like B-ALL. These findings will facilitate translation of AZD0466 dual BCL-2/BCL-XL inhibitor into ALL clinical trials, alone or in combination with standard chemotherapy and monoclonal antibodies.

AZD5153 was more effective than conventional monovalent BRD4 inhibitors, JQ1 and I-BET151, in inhibiting cell proliferation of a DHL-derived cell line and two DEL-derived cell lines, with at least 10-fold lower half growth inhibitory concentrations. To augment cell death induction, we added a novel BH3-mimicking BCL2 inhibitor AZD4320 to AZD5153, and found that these two agents had a mostly synergistic antitumor effect by increasing cells undergoing apoptosis in all three cell lines. These results provide a rationale for dual targeting of BRD4 and BCL2 using AZD5153 and AZD4320 as a therapeutic strategy against DHL and DEL.