Selective AXL Research Articles

P2.06-09 MiST3: A Phase II Study of Oral Selective AXL Inhibitor Bemcentinib (BGB324) in Combination with Pembrolizumab in pts with Malignant Mesothelioma

P2.06-09 MiST3: A Phase II Study of Oral Selective AXL Inhibitor Bemcentinib (BGB324) in Combination with Pembrolizumab in pts with Malignant Mesothelioma

1009PD - The identification of the AXL/Gas6 signalling axis as a key player of myelodysplastic syndrome (MDS) and the potential of the oral selective AXL inhibitor bemcentinib in the treatment of MDS

1009PD - The identification of the AXL/Gas6 signalling axis as a key player of myelodysplastic syndrome (MDS) and the potential of the oral selective AXL inhibitor bemcentinib in the treatment of MDS

Targeted inhibition of Axl receptor tyrosine kinase ameliorates anti-GBM-induced lupus-like nephritis

Glomerulonephritis (GN) is a typical lesion in autoantibody and immune complex disorders, including SLE. Because the Gas6/Axl pathway has been implicated in the pathogenesis of many types of GN, targeting this pathway might ameliorate GN. Consequently, we have studied the efficacy and mechanism of R428, a potent selective Axl inhibitor, in the prevention of experimental anti-GBM nephritis. Axl upregulation was investigated with Sp1/3 siRNA in the SV40-transformed mesangial cells. For Axl inhibition, a daily dose of R428 (125 mg/kg) or vehicle was administered orally. GN was induced with anti-GBM sera. Renal disease development was followed by serial blood urine nitrogen (BUN) determinations and by evaluation of kidney histology at the time of sacrifice. Axl-associated signaling proteins were analyzed by Western blotting and inflammatory cytokine secretion was analyzed by Proteome array. SiRNA data revealed the transcription factor Sp1 to be an important regulator of mesangial Axl expression. Anti-GBM serum induced severe nephritis with azotemia, protein casts and necrotic cell death. R428 treatment diminished renal Axl expression and improved kidney function, with significantly decreased BUN and glomerular proliferation. R428 treatment inhibited Axl and significantly decreased Akt phosphorylation and renal inflammatory cytokine and chemokine expression; similar effects were observed in anti-GBM antiserum-treated Axl-KO mice. These studies support a role for Axl inhibition in glomerulonephritis.

Identification of predictive and pharmacodynamic biomarkers associated with the first-in-class selective axl inhibitor bemcentinib across multiple phase II clinical trials.

2559Background: AXL expression is strongly associated with immunosuppression and therapy resistance in a wide range of cancers. Bemcentinib is a first-in-class, orally bioavailable, selective AXL T...

A randomized phase Ib/II study of the selective small molecule axl inhibitor bemcentinib (BGB324) in combination with either dabrafenib/trametinib or pembrolizumab in patients with metastatic melanoma.

9548Background: Upregulation of the receptor tyrosine kinase Axl has been linked with both a reduced response to PD-1 blockade and the development of therapy resistance to BRAF directed therapies i...

Phase II open-label, multi-centre study of bemcentinib (BGB324), a first-in-class selective AXL inhibitor, in combination with pembrolizumab in patients with advanced NSCLC.

3078Background: Bemcentinib (BGB324) is a first-in-class, oral, potent and highly selective inhibitor of the AXL tyrosine kinase currently in phase II clinical development across several cancer typ...

Analysis of anti-leukemic activity, predictive biomarker candidates, immune activation and pharmakodynamics in R/R AML and MDS in response to treatment with bemcentinib (BGB324), a first-in class selective AXL inhibitor, in a phase II open-label, multi-centre study.

7020Background: Bemcentinib (BGB324) is a first-in-class, oral selective inhibitor of the RTK AXL currently in ph II clinical development across several cancer types. AXL overexpression has been es...

A phase 1/2 dose escalation and expansion study of bemcentinib (BGB324), a first-in-class, selective AXL inhibitor, with docetaxel in patients with previously treated non-squamous NSCLC.

e21043Background: AXL is a receptor tyrosine kinase expressed on a variety of tumours as well as innate immune cells. AXL functions to regulate multiple cellular processes including tumour cell sur...

Development of Potent Inhibitors of Receptor Tyrosine Kinases by Ligand-Based Drug Design and Target-Biased Phenotypic Screening.

Pyrazolopyrimidines with potent antiproliferative properties were developed by an adaptive strategy that applies ligand-based design and phenotypic screening iteratively and is informed by biochemical assays. To drive development toward specific oncopathways, compounds were tested against cancer cells that overexpress, or not, AXL kinase. Identified phenotypic hits were found to inhibit oncotargets AXL, RET, and FLT3. Subsequent optimization generated antiproliferative lead compounds with unique selectivity profiles, including selective AXL inhibitors and a highly potent inhibitor of FLT3.

Abstract OT1-01-03: A phase II multi-center study of BGB324 in combination with pembrolizumab in patients with previously treated, locally advanced and unresectable or metastatic triple negative breast cancer (TNBC) or triple negative inflammatory breast cancer (TN-IBC)

Abstract Background. The AXL receptor tyrosine kinase is associated with poor overall survival in breast cancer. AXL signaling is an important regulator of tumor plasticity related to epithelial-to-mesenchymal transition (EMT) and stem cell traits that drive metastasis and drug resistance. Upregulation of AXL has been associated with reduced response to anti-PD-1 therapy. Signaling via AXL is also a key suppressor of the anti-tumor innate immune response, and AXL is expressed on several cells associated with the tumor immune microenvironment. Hence AXL signaling contributes uniquely to both tumor cell intrinsic and microenvironmental anti-tumor immune suppression mechanisms. We show that AXL is required for tumor immune evasion in the 4T1/Balb/C mammary adenocarcinoma model and that blocking AXL signaling with BGB324, a selective clinical-stage small molecule AXL kinase inhibitor, enhanced the effect of immune checkpoint blockade. BGB324 + anti-CTLA-4/anti-PD-1 treated tumors displayed enhanced infiltration of cytotoxic T lymphocytes and Natural Killer cells. Importantly, responding animals rejected orthotopic 4T1 tumor cell re-challenge, demonstrating sustained tumor immunity. These data provided a translational rationale for combining AXL targeted therapy with immune checkpoint inhibitors to enhance anti-cancer immune response. Study Design. BGBC007 (NCT03184558) is an open-label, single arm, multi-center phase II study designed to assess the anti-tumor activity of BGB324 in combination with pembrolizumab in patients with previously treated, locally advanced and unresectable, or metastatic TNBC or TN-IBC. Secondary objectives include safety and pharmacokinetic profile of BGB324 and pembrolizumab in combination. A single arm, extension of Simon's 2-stage design is employed with an interim and final analysis. Up to 56 evaluable patients will be enrolled. Recruitment will be halted once 28 evaluable patients have been entered to determine the Objective Response Rate (ORR, complete response and partial response). If 5 or fewer responses are observed in up to 28 patients, the trial will be terminated in favor of the null for futility. If 11 or more responses are observed, then the trial will be stopped in favor of the alternative for demonstration of activity. If 6 to 10 patients have an observed response then a further 28 patients may be evaluated. This design provides an overall power of 80.6% to test the stated null and alternative hypothesis. BGB324 will be administered orally, once daily, in a fasted state. Days 1, 2 and 3 of BGB324 administration consists of a 'loading' dose of 400 mg followed by a dose of 200 mg daily. A fixed dose of 200 mg pembrolizumab will be given by intravenous infusion over 30 minutes every 3 weeks. BGB324 and pembrolizumab will be given until disease progression, unacceptable dose toxicity, or until 106 weeks (35 cycles). Efficacy endpoints including ORR, Duration of Response, Progression Free Survival are based on tumor imaging evaluation by RECIST 1.1. Tumor specimens will be taken to assess AXL and PD-L1 expression. Citation Format: Yule M, Wnuk-Lipinska K, Davidsen K, Blø M, Hodneland L, Engelsen A, Kang J, Lie M, Bougnaud S, Aguilera K, Ahmed L, Rybicka A, Milde Nævdal E, Deyna P, Boniecka A, Straume O, Thiery J-P, Chouaib S, Brekken RA, Gausdal G, Lorens JB. A phase II multi-center study of BGB324 in combination with pembrolizumab in patients with previously treated, locally advanced and unresectable or metastatic triple negative breast cancer (TNBC) or triple negative inflammatory breast cancer (TN-IBC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-01-03.

Combination of bemcentinib (BGB324): A first-in-class selective oral AXL inhibitor, with pembrolizumab in patients with triple negative breast cancer and adenocarcinoma of the lung.

TPS43 Background: Activation of the receptor tyrosine kinase AXL has a profound suppressive effect on the innate immune system. AXL is overexpressed on multiple cell types in the tumour immune microenvironment including dendritic cells, NK cells and tumour-associated macrophages. AXL signalling in immune cells supports tumour immune escape by downregulating dendritic cell activity, modulating efferocytosis as well as favouring an immunosuppressive chemokine profile and M-MDSC expansion. AXL is prevalent in tumours resistant to anti-PD-1 therapy (Hugo, 2016). Axl expression in tumour cells confers resistance to effector T cell cytotoxicity. Bemcentinib (BGB324) is a first-in-class, highly selective and orally bioavailable small molecule AXL inhibitor in phase II clinical development. In pre-clinical models of pancreas, breast and lung cancer, inhibition of AXL signalling with bemcentinib reversed multiple tumour immune suppressive mechanisms as evidenced by increased infiltration of cytotoxic T lymphocytes, NK and NKT cells and decreased infiltration of M-MDSCs (Wnuk-Lipinska, 2017). Bemcentinib enhanced the effect of immune checkpoint blockade via PD-1 or CTLA-4 in lung and mammary adenocarcinoma mouse models and achieved sustained tumour immunity. Methods: BGBC007 (NCT03184558) and BGBC008 (NCT03184571) are open-label, phase II studies designed to assess the anti-tumour activity of bemcentinib in combination with pembrolizumab in patients with previously treated TNBC and adenocarcinoma of the lung respectively. All patients will be treated with bemcentinib in combination with pembrolizumab continuously for up to two years. The primary endpoint is objective response rate, secondary endpoints include duration of response, progression free survival according to RECIST 1.1, pharmacokinetics, safety and tolerability. Pretreatment tumour specimens are scheduled to assess AXL expression/signalling and PD-L1 expression; the levels of circulating immune-related cytokines and soluble AXL receptor will also be measured in longitudinal patient plasma samples. Both studies are open to recruitment. Clinical trial information: NCT03184558.

The immunomodulatory activity of bemcentinib (BGB324): A first-in-class selective oral AXL inhibitor in patients with relapsed/refractory acute myeloid leukemia or myelodysplastic syndrome.

70 Background: The tyrosine kinase AXL acts as suppressive immune checkpoint of the innate immune system. AXL signalling leads to immunosuppression and tumour immune escape by downregulating dendritic cell activity, modulating efferocytosis as well as favouring an immunosuppressive chemokine profile and M-MDSC expansion. Therefore it represents an interesting novel immune oncology target. Bemcentinib (BGB324) is a first-in-class, highly selective and orally bioavailable small molecule AXL inhibitor in phase II clinical development. In pre-clinical models, inhibition of AXL signalling with bemcentinib reversed multiple established immune suppressive mechanisms leading to increased infiltration of CTLs, NK and NKT cells and decreased infiltration of M-MDSCs (Wnuk-Lipinska, 2017). We explored safety, PK, efficacy and the effects of treatment with bemcentinib on the T- and B cell repertoire in patients with relapsed AML or MDS. Methods: BGBC003 (NCT02488408) is an open-label, dose finding study of bemcentinib in patients with R/R AML or MDS. Three dose levels have been explored and a loading dose of 400 mg on days one to three followed by 200 mg daily thereafter has been established as safe and recommended phase 2 dose. The TCRß repertoire was quantified by NGS of DNA isolated from PBMNCs using an Illumina MiSeq sequencer. TCRß genes and the IGH repertoire were analysed with BIOMED2-TCRß-A and –B and BIOMED2-FR1/-FR3 primer pools, respectively. Using genomic DNA as template, the amplicons were tagged with Illumina adapters and indices in two consecutive PCR reactions. Demultiplexing and FastQ formated data output was generated by the MiSeq reporter. Analysis of TCRß and IGH data was performed on a Microsoft Cloud using our in-house analysis pipeline Pippa. Results: Early evidence of antileukemic activity was seen. Diversification of the TCR and IGH repertoire could be detected in peripheral blood at day 21 of therapy compared to pre-treatment in three and two out of five matched samples, respectively. Conclusions: Bemcentinib shows preliminary evidence of immune modulation in AML. Clinical trial information: NCT02488408.

Abstract A205: Q701, a selective Axl and Mer inhibitor as an immune checkpoint inhibitor

Abstract Axl and Mer receptors are reported to have many functions, including promotion of epithelial-mesenchymal transition (EMT), resistance to antitumor therap,y and negative regulation of the innate immune response. Particular attention has been given to Axl and Mer receptor tyrosine kinase's (RTK) roles in regulating macrophage and NK cell activation as tumor cells exploit Axl and Mer signaling pathway to downregulate antitumor immunity, constituting an immune checkpoint. Q701 is a highly potent, selective, orally available Axl and Mer RTK inhibitor that can relieve immune suppression through innate immunity activation leading to T-cell activation. In various syngeneic mouse models, Q701 shows tumor regression activities by treatment of compound alone or in combination with other treatments, while Q701 has no direct cytotoxic activity against tested cell lines. Q701 treatment also show immune activation profile in tumor leading to T-cell activation. Q701 is under IND-enabling studies and a back-up program with Axl, Mer, and CSF1R inhibitors is in candidate nomination stage. Citation Format: Yeong-In Yang, Hwankyu Kang, Dongsik Park, Jiye Ahn, Jinho Choi, Seohyun Ahn, Jaeseung Kim, Kiyean Nam. Q701, a selective Axl and Mer inhibitor as an immune checkpoint inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A205.

Small-Molecule Inhibition of Axl Targets Tumor Immune Suppression and Enhances Chemotherapy in Pancreatic Cancer.

Activation of the receptor tyrosine kinase Axl is associated with poor outcomes in pancreatic cancer (PDAC), where it coordinately mediates immune evasion and drug resistance. Here, we demonstrate that the selective Axl kinase inhibitor BGB324 targets the tumor-immune interface to blunt the aggressive traits of PDAC cells in vitro and enhance gemcitibine efficacy in vivo Axl signaling stimulates the TBK1-NFκB pathway and innate immune suppression in the tumor microenvironment. In tumor cells, BGB324 treatment drove epithelial differentiation, expression of nucleoside transporters affecting gemcitabine response, and an immune stimulatory microenvironment. Our results establish a preclinical mechanistic rationale for the clinical development of Axl inhibitors to improve the treatment of PDAC patients.Significance: These results establish a preclinical mechanistic rationale for the clinical development of AXL inhibitors to improve the treatment of PDAC patients. Cancer Res; 78(1); 246-55. ©2017 AACR.

Abstract IA22: Emerging signaling pathways in prostate cancer therapy

Abstract One major prerequisite to develop targeted therapies is the identification of relevant cellular targets and the identification of the relevant patient population in which to test these therapies. Although androgen ablation therapy, surgery and radiation therapy are effective for the treatment of local prostate cancer (PCa), there is no effective treatment available for patients with metastatic disease. The receptor tyrosine kinase Axl has been implicated in the pathology of many cancers. Increased Axl expression correlates with metastasis, aggressive behavior, and poor survival and have been linked with resistance to chemotherapeutic regimens in tumors. Interestingly, in these reports inhibition of Axl leads to restoration of sensitivity to drug therapy, indicating that Axl may represent a promising therapeutic target whose inhibition could prevent or overcome acquired resistance to some drugs. We have shown that Axl is overexpressed in PCa and is an essential regulator of PCa proliferation and tumor growth. Axl expression is elevated in hormone-refractory PCa cell lines and Axl knockdown reduces migration and invasion and tumor formation in vivo. The Axl ligand, GAS6, acts as a growth and/or survival factor and its binding to Axl activates PI3K and its downstream targets S6K and Akt. Activation of these pathways has been reported to induce nuclear translocation of the transcription factor nuclear factor kappa B (NF-κB), IL-6 production and STAT3 activation. The molecule named R428 (now renamed BGB324) inhibits in a dose-dependent manner Gas6 stimulated Axl autophosphorylation and activity with high specificity, selectivity, and affinity and blocks Axl-dependent signaling events, such as Akt phosphorylation, cell invasion, and pro-inflammatory cytokine production. R428/BGB324 effectively prevents or reverses acquired resistance to several cancer therapies in preclinical models. Most importantly, as a result of these and other encouraging preclinical findings of therapeutic value this first-in-class, highly selective Axl inhibitor has entered the clinical trial phase. Docetaxel, the main chemotherapeutic drug used in aggressive prostate cancer treatment, has shown limited efficacy against metastatic PCa, primarily due to invariable development of drug resistance, necessitating a thorough investigation of the mechanisms underlying this drug resistance and the development of novel, more efficacious therapies to prevent or overcome resistance. Preliminary data from our laboratory provide strong evidence for the notion that Axl plays a pivotal role in resistance to docetaxel and possibly cabazitaxel treatment. Importantly, Axl inhibitor R428 enhances docetaxel efficacy. Citation Format: Luiz F. Zerbini. Emerging signaling pathways in prostate cancer therapy [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr IA22.

MA 02.09 A Ph I/II Study of BGB324, a Selective AXL Inhibitor as Monotherapy and in Combination with Erlotinib in Advanced NSCLC

MA 02.09 A Ph I/II Study of BGB324, a Selective AXL Inhibitor as Monotherapy and in Combination with Erlotinib in Advanced NSCLC

Abstract CT056: A Phase Ib/II randomised open label study of BGB324 in combination with pembrolizumab or dabrafenib/trametinib compared to pembrolizumab or dabrafenib/trametinib alone, in patients with advanced non-resectable (Stage IIIc) or metastatic (Stage IV) melanoma

Abstract Background. MAPK inhibitors and immune checkpoint inhibitors are major breakthroughs in metastatic melanoma showing high response rates and durable responses. To further improve patient outcome, and to overcome treatment resistance, combination strategies have been suggested. We have initiated a phase Ib/II randomized clinical trial with the selective AXL inhibitor BGB324 (IC50=14 nM R428 Bergen Bio AS) with or without immune check point inhibition (pembrolizumab) or MAPK inhibitors (dabrafenib+trametinib) (NCT02872259). Upregulation of the AXL kinase has been associated with reduced response to anti-PD-1 therapy. The drug resistant low MITF/ high AXL melanoma signature has been associated with an immune suppressive micro-environment. AXL is a key negative feedback regulator of the innate immune response and attenuates macrophage, dendritic and natural killer (NK) cell activity. Hence, AXL signaling contributes to both tumor intrinsic and microenvironmental immune suppression mechanisms. Further we have recently shown that BGB324 sensitizes the highly metastatic K1736 murine melanoma tumors to anti-PD-1 treatment. This provides a rationale for targeting AXL to enhance the anti-cancer immune response. AXL dependent cell plasticity signaling pathways confer resistance to inhibitors of BRAF/MEK. Melanomas display either a high E-cadherin/high MITF-M expression on the one hand, or high N-cadherin/high AXL expression on the other. The low MITF/high AXL phenotype is linked to drug-resistance in mutant BRAF and NRAS melanoma cell lines. Interestingly, AXL-mediated resistance to BRAF and MEK targeting agents could be predicted by levels of soluble AXL receptor in patient blood samples and prevented by coadministration of BGB324, Methods. This is a Phase Ib/II, multicentre, open label, parallel group study in patients with metastatic melanoma. Part 1 is a dose selection phase in up to 12 patients to evaluate the safety of BGB324 when administered in combination with dabrafenib+trametinib and to determine the BGB324 dose to be administered in the combination in Part 2 and Part 3. Part 2 is an open label, multiple arm, randomised treatment phase evaluating efficacy and safety of pembrolizumab and dabrafenib+trametinib in combination with BGB324 as first line treatment in 80 patients with advanced melanoma compared to pembrolizumab or dabrafenib/trametinib alone. Patients will be stratified according to BRAF status and tumor load to receive pembrolizumab or dabrafenib+trametinib with or without BGB324, randomised in a 2:1 ratio. Part 3 is an open label, multiple arm, non-randomised treatment phase evaluating efficacy and safety of pembrolizumab and dabrafenib/trametinib in combination with BGB324 or alone, as second line treatment in patients continuing from Part 1 or Part 2. Co-primary endpoints are safety and response rates according to RECIST 1.1. Enrollment began in January 2017. Citation Format: Oddbjorn Straume, Cornelia Schuster, James Lorens, Bjørn Tore Gjertsen. A Phase Ib/II randomised open label study of BGB324 in combination with pembrolizumab or dabrafenib/trametinib compared to pembrolizumab or dabrafenib/trametinib alone, in patients with advanced non-resectable (Stage IIIc) or metastatic (Stage IV) melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT056. doi:10.1158/1538-7445.AM2017-CT056

Abstract P2-04-08: BGB324, a selective small molecule inhibitor of the receptor tyrosine kinase AXL, enhances immune checkpoint inhibitor efficacy in mammary adenocarcinoma

Abstract The AXL receptor tyrosine kinase is associated with poor overall survival in breast cancer. Axl signaling is an important regulator of tumor plasticity related to epithelial-to-mesenchymal transition (EMT) and stem cell traits that drive metastasis and drug resistance. Signaling via AXL is also a key suppressor of the anti-tumor innate immune response. AXL is expressed on several cells associated with the tumor immune microenvironment including natural killer cells, dendritic cells and tumor-associated macrophages. AXL is required for tumor immune evasion in mammary adenocarcinoma models and EMT-mediated resistance to cytotoxic T cell and natural killer (NK)-cell mediated cell killing. Hence AXL signaling contributes uniquely to both tumor cell intrinsic and microenvironmental anti-tumor immune suppression mechanisms in breast cancer. We evaluated whether blocking AXL signaling with BGB324, a selective clinical-stage small molecule Axl kinase inhibitor, enhances the effect of immune checkpoint blockade in the aggressive mammary adenocarcinoma (4T1) syngeneic (Balb/C) mouse modelthat display limited immunogenicity. Immune therapy with anti-CTLA-4/anti-PD-1 increased AXL and EMT-marker expression in 4T1 tumors, and correlated with lack of response to immune therapy. Combination treatment with BGB324 (50 mg/kg bid) significantly enhanced responsiveness to anti-CTLA-4/anti-PD-1 treatment (10 mg/kg of each, 4 doses) in Balb/C mice bearing established 4T1 tumors. The combination of BGB324 + anti-CTLA-4/anti-PD-1 resulted in durable primary tumor clearance in 23 % of treated mice versus 5.6% obtained with anti-CTLA-4/anti-PD-1 alone (p=0.0157). In a separate study, BGB324 + anti-CTLA-4 treated resulted in 22% long-term primary tumor clearance while no response was observed with anti-CTLA4 treatment alone. The extensive metastasis to the lung, liver and spleen characteristic of this model were concomitantly abrogated in the animals responding to the combination treatment. In addition, BGB324 + anti-CTLA-4/anti-PD-1 treated tumors displayed enhanced infiltration of cytotoxic T lymphocytes (CTLs). Enhanced presence of CTLs was also detected in spleens from animals responding to treatment. BGB324 + anti-CTLA-4/anti-PD-1 treatment increased the number of NK cells, macrophages and polymorphonuclear neutrophils, but decreased the number of mMDSC. Importantly, responding animals rejected orthotopic 4T1 tumor cell re-challenge, demonstrating sustained tumor immunity. Together with recent results in other tumor types that support a prominent role for AXL in resistance to immune therapy and encouraging results from ongoing clinical trials with BGB324, support combining BGB324 with immune checkpoint inhibitors to improve treatment of breast cancer. Citation Format: Lorens JB, Lipinska KW, Davidsen K, Blø M, Hodneland L, Engelsen A, Kang J, Lie MK, Bougnaud S, Aguilera K, Ahmed L, Rybicka A, Nævdal EM, Deyna P, Boniecka A, Straume O, Chouaib S, Brekken RA, Gausdal G. BGB324, a selective small molecule inhibitor of the receptor tyrosine kinase AXL, enhances immune checkpoint inhibitor efficacy in mammary adenocarcinoma [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-08.

Implication of the Receptor Tyrosine Kinase AXL in Head and Neck Cancer Progression.

Head and neck squamous cell carcinoma (HNSCC) remains a clinical challenge and identification of novel therapeutic targets is necessary. The receptor tyrosine kinase AXL has been implicated in several tumor entities and a selective AXL small molecule inhibitor (BGB324) is currently being tested in clinical trials for patients suffering from non-small cell lung cancer or acute myeloid leukemia. Our study investigates AXL expression during HNSCC progression and its use as a potential therapeutic target in HNSCC. AXL protein expression was determined in a HNSCC cohort (n = 364) using immunohistochemical staining. For functional validation, AXL was either overexpressed or inhibited with BGB324 in HNSCC cell lines to assess proliferation, migration and invasion. We found AXL protein expression increasing during tumor progression with highest expression levels in recurrent tumors. In HNSCC cell lines in vitro, AXL overexpression increased migration as well as invasion. Both properties could be reduced through treatment with BGB324. In contrast, proliferation was neither affected by AXL overexpression nor by inhibition with BGB324. Our patient-derived data and in vitro results show that, in HNSCC, AXL is important for the progression to more advanced tumor stages. Moreover, they suggest that AXL could be a target for precision medicine approaches in this dismal tumor entity.

BGB324, an Orally Available Selective Axl Inhibitor Exerts Anti-Leukemic Activity in the First-in-Patient Trial BGBC003 and Induces Unique Changes in Biomarker Profiles

Introduction: The RTK Axl represents a therapeutic target promoting AML cell proliferation and survival by pleiotropic mechanisms. Signalling through Axl is also known to suppress immune reactions mainly by inhibiting pro-inflammatory responses of antigen presenting cells. BGB324 is an orally available selective potent inhibitor of Axl, which is currently being investigated in a Phase 1 a/b trial in AML and MDS. We report here the clinical data and the impact of BGB324 on the Axl signalling pathway. Furthermore, we evaluated the T cell receptor (TCR) repertoire in order to assess potential effects of BGB324 on the immune response in AML patients.Methods: Twenty-five patients (twenty-one with relapsed/refractory AML and four with MDS) were treated in a classical 3+3 dose escalation design. Three dose levels were explored 400/100 mg (loading dose d1-2/maintenance dose), 600/200 mg and 900/300 mg. Serial bone marrow samples (BM) were available from n=5 patients. By means of immunoblotting and ELISA we analyzed phosphorylation of Axl and its downstream targets Erk/MapK and Akt as well as the levels of soluble Axl (sAxl) and osteopontin in plasma. The TCRß repertoire was quantified by Next Generation Sequencing of DNA isolated from peripheral blood MNCs using an Illumina MiSeq sequencer. TCRß gene containing the entire Vß, Dß and Jß segments were amplified with BIOMED2-TCRß-A and -B primer pools. Using genomic DNA as template, the amplicons were tagged with Illumina adapters and indices in two consecutive PCR reactions. Demultiplexing and FastQ formated data output was generated by the MiSeq reporter. Analysis of TCRß data was performed on a Microsoft Cloud using our in-house analysis pipeline Pippa, which relies on MiXCR analysis tools.Results: Treatment was generally well-tolerated. Diarrhea and fatigue represented the most frequent adverse events, which were mostly CTC Grade 1 or 2. One DLT (QTc prolongation) occurred and the MTD has not yet been reached. Steady-state levels of BGB324 were reached between three and six days after initiation of treatment. One AML patient achieved a CRi of 5 months, a second achieved a PR and another achieved clearance of circulating blasts accompanied by peripheral blood count recovery > 3 months (ORR 10%). Four additional AML patients (25%) experienced disease stabilisation for more than four months. Two MDS patients experienced a PR.From the five patients in whom BM samples were available three experienced either an objective response or disease stabilization for more than four months and two had progressive disease. We could detect phosphorylated Axl (pAxl) before treatment and decreased pAxl level after 21 days of treatment in 3 out of 3 responders/patients with SD while could not detect pAxl before treatment in the patients with PD (n=5; p=0.025). The patients with response or SD showed inhibition of pErk and pAxl (2 out of 3) or no change of the activity of these Axl downstream pathways (1 out of 3). The patients with PD showed increased pErk and pAkt level after treatment (n=5; p=0.082).Treatment with BGB324 led to an increase in the levels of sAxl after 21 days of treatment in the plasma of 67% of analyzed patients (n=12). SAxl levels were positively correlated to compound exposure (n=12; r=0.829), indicating that sAxl might be used as a biomarker of target engagement. The highest level of sAxl was seen in the patient who achieved a PR. Osteopontin levels decreased in 67% of analyzed patients after three weeks of treatment with BGB324 indicating modulation of this protein by BGB324. However, there was no correlation between increases of sAxl and decreases of osteopontin in this patient cohort.Interestingly, we could demonstrate diversification of the TCR repertoire by higher abundance of small T cell clones after three weeks of therapy with BGB324 compared to pre-treatment levels in two out of four analysed patients.Conclusion: BGB324 is well tolerated in AML patients and exhibits anti-leukemic activity. BGB324 has on-target activity in AML patients and blocks the phosphorylation of Axl and its downstream pathways. Furthermore, BGB324 can induce a diversification of the TCR repertoire in AML patients and might hold potential as an immune-activating drug. DisclosuresSonja:BergenBio: Honoraria, Other: Travel Support, Research Funding. Gjertsen:BerGenBio AS: Equity Ownership, Membership on an entity’s Board of Directors or advisory committees; Boehringer Ingelheim: Membership on an entity’s Board of Directors or advisory committees; Kinn Therapeutics AS: Equity Ownership. Micklem:BerGenBio AS: Employment, Equity Ownership. Janning:Teva: Honoraria. Fiedler:Pfizer: Research Funding; GSO: Other: Travel; Amgen: Consultancy, Other: Travel, Patents & Royalties, Research Funding; Kolltan: Research Funding; Ariad/Incyte: Consultancy; Novartis: Consultancy; Gilead: Other: Travel; Teva: Other: Travel. Cortes:ARIAD: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding.