SRA515

Our work demonstrates that CDK9 inhibition disrupts multiple oncogenic pathways and positions CDKI-73 as a promising therapeutic agent for prostate cancer, particularly aggressive, therapy-resistant subtypes.

This first-in-human, phase I study investigated AZD5153 alone or with olaparib in patients with relapsed/refractory solid tumors or lymphoma. These results show AZD5153 was tolerable as monotherapy and in combination at the RP2Ds; common toxicities were fatigue, hematologic AEs, and gastrointestinal AEs. Strong evidence of peripheral target engagement was observed.

Methods Single-cell RNA sequencing (scRNA-seq) was performed in Phase II clinical trial of pembrolizumab (anti-Programmed cell death 1(PD-1)) in hepatitis B virus-related HCC patients ( NCT03419481 ). Notably, a clinically-trialed BRD4 specific inhibitor AZD5153 synergized with PD-L1 antibody to suppress tumor growth and ameliorated immunosuppressive microenvironment, which was accompanied by significant reduction and increase in MaVEC and LEC densities, respectively. Conclusions Our data demonstrated that epigenetic reversion of LEC-to-MaVEC trans-differentiation by BRD4 inhibition may be a potential strategy for improving HCC immunotherapy.

Adding IFNß1 to cells treated with acalabrutinib partially rescued PAX5 activation. Our results demonstrate AZD5153 enhances the efficacy of acalabrutinib through PAX5 and BCR mechanisms that are critical for ABC-DLBCL.

Treatment with PROTAC ARV825 that degrades BET proteins, resulted in similar growth inhibitory effects...Combination treatments of BETi+topotecan/ifosfamide indicated that AZD5153 potentiated the anti-cancer effect of salvage therapy in TT2 OS PDX, was well tolerated, and increased the probability of survival in mice. Efficacy in an OS RS+ metastatic lesion model is in progress. These data collectively suggest that BET inhibition as a single agent and in combination with low-dose salvage therapy holds promise as novel treatment strategies for inducing RS-mediated cell death in aggressive OS.

To solve this problem, we found that BRD4 inhibitor AZD5153 and PARP inhibitor olaparib had a widespread synergistic effect in multiple models with different gene backgrounds. The similar results of these models further proved that the mechanism identified was consistent with the biological process occurring in ovarian cancer patients after drug treatment. This consistency between the results of different models suggests the possibility of translating these laboratory research findings into clinical studies towards developing treatments.

We evaluated the anti-lymphoma activity of the isoform-specific bivalent BET inhibitor AZD5153 (AZD) and the pan-BET inhibitor I-BET151 (I-BET) as single agents and in combination with SYK inhibitor Entospletinib (Ento) in vitro. Genes such as ADGRA2, MYB, TNFRSF11A, S100A10, PLEKHH3, DHRS2 and FOXP1-AS1 were identified as possible key regulators. Simultaneous inhibition of BET and SYK enhanced the anti-proliferative effects, and induced a combination-specific gene expression signature.

We tested two BRD4 inhibiter (BRD4i: AZD5153 and JQ-1) and genetic BRD4 depletion enhances radiation-induced DNA damage, making it a potential radiosensitizer in the treatment of DIPG. In vivo studies revealed increased survival of animals treated with combination therapy of RT and BRD4i in compared to either monotherapy. Together, these results highlight BRD4i as a potential radiosensitizer and provide a rationale for developing combination therapy with radiation in the treatment of DIPG.

Functional Assays : RNA interference and inhibitors that selectively target GLS (CB-839), DHODH (Teriflunomide, Leflunomide, Vidofludimus, Brequinar and BAY 2402234) or BRD4 (MZ-1; JQ1; AZD5153; Mivebresib and Birabresib) potently and specifically diminish the clonogenic potential of several SCCHN cell lines. However, none of these treatments induce comparable apoptosis in the ex vivo SCCHN tumour tissue. Conclusion The challenges presented by the tumour microenvironment in diminishing the potential of several promising therapies will have to be characterised further, which is the primary focus of our current studies.

In conclusion, these data suggested that MUS81 regulated ATR/CHK1 activation, a key signaling pathway in the G2M checkpoint, and targeting MUS81 enhanced the antitumor efficacy of talazoparib. Therefore, AZD5153 combined with talazoparib may represent a promising therapeutic strategy for patients with MUS81 proficient gastric cancer.

This may explain why AZD5153 acted in concert with FK866, a potent NAMPT inhibitor, in reducing HCC cell proliferation and clonogenic survival. In conclusion, our results identified novel targets of BRD4 in the HCCLM3 cell genome and demonstrated anti-HCC efficacy of AZD5153, which was potentiated in combination with an NAMPT inhibitor.

In summary, our results demonstrate AZD5153 enhances the efficacy of acalabrutinib, and our in vitro data suggest adding AZD5153 to acalabrutinib concentrations much lower than the clinical equivalent dose results in a similar biomarker response. We show that this drug combination attenuates interferon signaling, which supports the mechanism of AZD5153 and acalabrutinib inhibiting PAX5 signaling in ABC-DLBCL.

The effects of BET inhibitors (BETi), AZD5153 and OTX-015, as single agents and in combination with drugs used in salvage therapy such as topotecan were evaluated for effects on OS cell growth, PARP cleavage, and the DNA damage repair network. In vivo combination treatments of BETi+topotecan are in progress. These data collectively suggest that BET inhibition alongside salvage therapy holds promise as a novel treatment strategy for inducing RS-mediated cell death in aggressive OS.

Moreover, this study revealed that AZD5153 and palbociclib had a synergistic lethal effect on inducing the cell cycle arrest and increasing apoptosis, even in RB-deficient cell lines. Based on these results, it is anticipated that this class of drugs, including AZD5153, which inhibit the cell cycle-related protein and MAPK/PI3K-AKT pathway, will exhibit synergistic effects with palbociclib in OC.

We suggest that AZD5153, a novel dual-BRD4 inhibitor, can reduce MYCN levels in both anaplastic and nonanaplastic Wilms tumor cell lines, reduces tumor volume in Wilms tumor PDXs, and should be further explored for its therapeutic potential.

GSEA is a powerful approach to identify upregulated genes and potential therapeutic targets. Dinaciclib-AZD5153 combination therapy can be effective against MYCN-amplified and TERT-overexpressing neuroblastoma tumors.

P1, N=49, Completed, AstraZeneca | Active, not recruiting --> Completed

In this study, we investigated the preclinical activity of two BRD4i, AZD5153 and PLX51107, and their cooperative role with the BCL2 inhibitor venetoclax and BTK inhibitor ibrutinib in CLL. Modulation of BCL-2 family members following BRD4 inibition could play a role in the synergistic activity observed in our studies. A better understanding of the key signaling pathways involved in proliferation and survival of CLL cells impacted by BRD4i in combination with venetoclax and ibrutinib would provide a proof-of-concept rationale for studies validating BRD4i as epigenetic approach to target BCR signaling in CLL.

P1, N=49, Active, not recruiting, AstraZeneca | Recruiting --> Active, not recruiting | N=100 --> 49

P1, N=100, Recruiting, AstraZeneca | N=72 --> 100

Pan- and isoform-specific BET inhibitors applied as mono substances in low concentrations restrain cell proliferation and induce apoptosis/necrosis on CLBL-1. CLBL-1 is resistant to Entospletinib used as monotherapy. Combining Entospletinib with I-BET151 or AZD5153 does not significantly enhance antiproliferative effect and induction of apoptosis/necrosis toward CLBL-1.

Pan- and isoform-specific BET inhibitors applied as mono substances in low concentrations restrain cell proliferation and induce apoptosis/necrosis on CLBL-1. CLBL-1 is resistant to Entospletinib used as monotherapy. Combining Entospletinib with I-BET151 or AZD5153 does not significantly enhance antiproliferative effect and induction of apoptosis/necrosis toward CLBL-1.

Pan- and isoform-specific BET inhibitors applied as mono substances in low concentrations restrain cell proliferation and induce apoptosis/necrosis on CLBL-1. CLBL-1 is resistant to Entospletinib used as monotherapy. Combining Entospletinib with I-BET151 or AZD5153 does not significantly enhance antiproliferative effect and induction of apoptosis/necrosis toward CLBL-1.

Entospletinib did not enhance the inhibitory effects of the pan- or isoform-specific BET.

Collectively, we show that Mus81 is a regulator of ZEB1 and promotes metastasis in gastric cancer. Importantly, we demonstrate that the BRD4 inhibitor AZD5153 can potentially be used as an effective anti-metastasis drug because of its effect on Mus81.

While subtle changes in chemistry around CFT-743 had negligible impact on vitro potency, the effect on therapeutic index was significant.In vitro, CFT-743 is more potent than a BET inhibitor (AZD5153) and a CDK9 inhibitor (dinaciclib) in 100% and 97% of 38 leukemia lines tested...Pre-dosing mice with the CRBN binding molecule pomalidomide significantly attenuates CFT-743 activity (TGI 40%) rendering the observed efficacy on par with BET inhibitor CPI-203 (TGI 2%) and thus confirming superior efficacy is dependent on BET degradation...In normal tissues, CFT-743 promotes a similar rapid and near complete loss of BRD4, however; protein levels begin to recover ≤ 6hr post dose. This pharmacodynamic behavior provides a rationale as to why CFT-743 is efficacious and well tolerated.Collectively, these data highlight the in vivo features important for efficacy and tolerability with BET degraders and establish the relationships between degrader pharmacokinetics, target protein degradation and efficacy.

Two BET inhibitors, JQ1 and AZD5153, increased and prolonged AZD1775-induced DNA double-strand breaks (DSBs) and concomitantly repressed genes related to nonhomologous end joining (NHEJ), including XRCC4 and SHLD1. Furthermore, pharmaceutical inhibition of BET or knockdown of the BET protein BRD4 markedly diminished NHEJ activity, and the BET-inhibitor treatment also repressed myelin transcription factor 1 (MYT1) expression and promoted mitotic entry with subsequent mitotic catastrophe when combined with WEE1 inhibition. Our findings reveal that BET proteins, predominantly BRD4, play an essential role in DSB repair through the NHEJ pathway, and further suggest that combined inhibition of BET and WEE1 could serve as a novel therapeutic strategy for NSCLC.

Importantly, the 3-D microfluid model demonstrates that AZD5153 sensitizes ovarian cancer to anti-PD-L1 therapy. Our results clarify that besides eliminating tumor cells directly, AZD5153 works as a regulator of the TAM phenotype, providing a novel strategy combining AZD5153 and PD-1/PD-L1 antibody that could benefit HGSOC patients.

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.

P1, N=60, Recruiting, AstraZeneca | Trial completion date: Jun 2020 --> Dec 2020 | Trial primary completion date: Jun 2020 --> Dec 2020

The mechanism of action of the drugs combined with acalabrutinib are as follows: AZD9150 is a 16-nucleotide antisense oligonucleotide designed to target and down-regulate expression of human STAT3 mRNA; administered intravenously. AZD6738 is an inhibitor of ATR; administered orally. Hu5F9-G4 is an anti-CD47 antibody and rituximab is an anti-CD20 antibody; both administered intravenously. AZD5153 is a BRD4 inhibitor; administered orally. In summary, PRISM is a unique platform protocol designed to efficiently evaluate targeted agents in R/R aggressive B-cell lymphoma with an emphasis on comprehensive translational and molecular investigations.

Notably, 2/5 PDX models screened (DFAM-68555 and DFAM-10360) were insensitive to both venetoclax and the combination of venetoclax + 5-azacytidine (HMA) ex vivo...However, in DFAM-68555, AZD5153, AZD5991, and AZD2811 showed improved activity over venetoclax alone (67%, 54%, and 67% vs. 26% decrease in viability for venetoclax alone, respectively)...Using this platform and subsequent in vivo efficacy, we identified venetoclax combinations across multiple mechanisms (pro-apoptotic, cell cycle regulation, transcriptional regulation, DNA damage response) with activity in venetoclax-insensitive models. These results suggest potential therapeutic options to explore clinically for AML patients.