Abstract 985: BI 905711 selectively induces apoptosis and anti-tumor response in TRAILR2/CDH17- expressing pancreatic cancer models

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal adult cancers with an average 5-year survival rate of less than 10% due in part to the limited number of effective therapies. Activation of TRAILR2 (Tumor necrosis factor (TNF)-Related Apoptosis-Inducing Ligand Receptor 2) has emerged as an important therapeutic concept in cancer treatment. Traditional TRAILR2 agonists have had limited clinical success due to lack of efficacy or, importantly, severe hepatotoxicity. Here we present anti-tumor activity in preclinical PDAC models for BI 905711, a first-in-class tetravalent bispecific antibody specifically designed to overcome the disadvantages of previous strategies targeting TRAILR2.

BI 905711 serves as a uniquely specific, and liver-sparing therapeutic by targeting tumors that co-express TRAILR2 and another cell surface protein CDH17, which has ~40% prevalence in PDAC and is not expressed in normal liver. Working from a large cohort of molecularly characterized PDAC PDX models, we provide the first preclinical evidence of BI 905711 exhibiting robust anti-tumor activity in difficult to treat PDAC PDX models. Anti-tumor efficacy in responding models correlated with strong induction of Caspases 3/7 and 8 activation in tumors 24 hours after a single dose of BI 905711, and was associated with the presence and expression levels of TRAILR2 and CDH17 proteins. Evaluation of models with differential TRAILR2 and CDH17 expression profiles helped define the expression threshold for each target that is associated with response, upon which clinical assay development is in process for future patient stratification. Additionally, response was also associated with PDAC molecular subtypes utilizing a novel proprietary gene co-expression network developed from a curated cohort of PDAC PDX tumors. Responders to BI 905711 were identified primarily within the classical and quasi-basal/hybrid subtypes when TRAILR2 was adequately co-expressed. This correlates with an enrichment pattern of CDH17 gene expression that is mostly within the classical gene cluster and strongly anti-correlated with basal-like cluster enrichment.

Robust preclinical anti-tumor activity of BI 905711 in TRAILR2 and CDH17-expressing PDAC PDX models, along with this antibody's potential for a favorable safety profile, has justified the enrollment of pancreatic cancer patients in the ongoing BI 905711 FIH Phase I clinical trial (NCT04137289).

Citation Format: Jing Han, Annette A. Machado, Mikhila Mahendra, Joseph R. Daniele, Christopher A. Bristow, Justin Kwang-Lay Huang, Alessandro Carugo, Robert A. Mullinax, Benjamin J. Bivona, Ningping Feng, Poojabahen Gandhi, Norbert Schweifer, Paolo Maria Chetta, Juan Manuel Garcia-Martinez, Frank Hilberg, Christopher P. Vellano, Timothy P. Heffernan, Joseph R. Marszalek. BI 905711 selectively induces apoptosis and anti-tumor response in TRAILR2/CDH17- expressing pancreatic cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 985.

Sequential Administration of XPO1 and ATR Inhibitors Enhances Therapeutic Response in TP53-mutated Colorectal Cancer

BACKGROUND & AIMS

Understanding the mechanisms by which tumors adapt to therapy is critical for developing effective combination therapeutic approaches to improve clinical outcomes for patients with cancer.

METHODS

To identify promising and clinically actionable targets for managing colorectal cancer (CRC), we conducted a patient-centered functional genomics platform that includes approximately 200 genes and paired this with a high-throughput drug screen that includes 262 compounds in four patient-derived xenografts (PDXs) from patients with CRC.

RESULTS

Both screening methods identified exportin 1 (XPO1) inhibitors as drivers of DNA damage-induced lethality in CRC. Molecular characterization of the cellular response to XPO1 inhibition uncovered an adaptive mechanism that limited the duration of response in TP53-mutated, but not in TP53-wild-type CRC models. Comprehensive proteomic and transcriptomic characterization revealed that the ATM/ATR-CHK1/2 axes were selectively engaged in TP53-mutant CRC cells upon XPO1 inhibitor treatment and that this response was required for adapting to therapy and escaping cell death. Administration of KPT-8602, an XPO1 inhibitor, followed by AZD-6738, an ATR inhibitor, resulted in dramatic antitumor effects and prolonged survival in TP53-mutant models of CRC.

CONCLUSIONS

Our findings anticipate tremendous therapeutic benefit and support the further evaluation of XPO1 inhibitors, especially in combination with DNA damage checkpoint inhibitors, to elicit an enduring clinical response in patients with CRC harboring TP53 mutations.

Allosteric SHP2 Inhibitor, IACS-13909, Overcomes EGFR-Dependent and EGFR-Independent Resistance Mechanisms toward Osimertinib

Src homology 2 domain-containing phosphatase (SHP2) is a phosphatase that mediates signaling downstream of multiple receptor tyrosine kinases (RTK) and is required for full activation of the MAPK pathway. SHP2 inhibition has demonstrated tumor growth inhibition in RTK-activated cancers in preclinical studies. The long-term effectiveness of tyrosine kinase inhibitors such as the EGFR inhibitor (EGFRi), osimertinib, in non-small cell lung cancer (NSCLC) is limited by acquired resistance. Multiple clinically identified mechanisms underlie resistance to osimertinib, including mutations in EGFR that preclude drug binding as well as EGFR-independent activation of the MAPK pathway through alternate RTK (RTK-bypass). It has also been noted that frequently a tumor from a single patient harbors more than one resistance mechanism, and the plasticity between multiple resistance mechanisms could restrict the effectiveness of therapies targeting a single node of the oncogenic signaling network. Here, we report the discovery of IACS-13909, a specific and potent allosteric inhibitor of SHP2, that suppresses signaling through the MAPK pathway. IACS-13909 potently impeded proliferation of tumors harboring a broad spectrum of activated RTKs as the oncogenic driver. In EGFR-mutant osimertinib-resistant NSCLC models with EGFR-dependent and EGFR-independent resistance mechanisms, IACS-13909, administered as a single agent or in combination with osimertinib, potently suppressed tumor cell proliferation in vitro and caused tumor regression in vivo. Together, our findings provide preclinical evidence for using a SHP2 inhibitor as a therapeutic strategy in acquired EGFRi-resistant NSCLC. SIGNIFICANCE: These findings highlight the discovery of IACS-13909 as a potent, selective inhibitor of SHP2 with drug-like properties, and targeting SHP2 may serve as a therapeutic strategy to overcome tumor resistance to osimertinib.

Discovery of IPN60090, a Clinical Stage Selective Glutaminase-1 (GLS-1) Inhibitor with Excellent Pharmacokinetic and Physicochemical Properties

Inhibition of glutaminase-1 (GLS-1) hampers the proliferation of tumor cells reliant on glutamine. Known glutaminase inhibitors have potential limitations, and in vivo exposures are potentially limited due to poor physicochemical properties. We initiated a GLS-1 inhibitor discovery program focused on optimizing physicochemical and pharmacokinetic properties, and have developed a new selective inhibitor, compound 27 (IPN60090), which is currently in phase 1 clinical trials. Compound 27 attains high oral exposures in preclinical species, with strong in vivo target engagement, and should robustly inhibit glutaminase in humans.

Discovery of IACS-9439, a Potent, Exquisitely Selective, and Orally Bioavailable Inhibitor of CSF1R

Tumor-associated macrophages (TAMs) have a significant presence in the tumor stroma across multiple human malignancies and are believed to be beneficial to tumor growth. Targeting CSF1R has been proposed as a potential therapy to reduce TAMs, especially the protumor, immune-suppressive M2 TAMs. Additionally, the high expression of CSF1R on tumor cells has been associated with poor survival in certain cancers, suggesting tumor dependency and therefore a potential therapeutic target. The CSF1-CSF1R signaling pathway modulates the production, differentiation, and function of TAMs; however, the discovery of selective CSF1R inhibitors devoid of type III kinase activity has proven to be challenging. We discovered a potent, highly selective, and orally bioavailable CSF1R inhibitor, IACS-9439 (1). Treatment with 1 led to a dose-dependent reduction in macrophages, promoted macrophage polarization toward the M1 phenotype, and led to tumor growth inhibition in MC38 and PANC02 syngeneic tumor models.

Abstract C036: Discovery of IACS-13909, an allosteric SHP2 inhibitor that overcomes multiple mechanisms underlying osimertinib resistance

Osimertinib, a third generation EGFR inhibitor, is a front-line therapy for EGFR mutated non-small lung cancer (NSCLC). The long-term effectiveness of osimertinib is limited by acquired resistance. Clinically identified resistance mechanisms include EGFR-dependent mechanisms such as mutations on EGFR that preclude drug binding, and EGFR-independent activation of the MAPK pathway, for instance via activation of alternate RTKs. It has also been noted that frequently a tumor from a single patient harbors more than one resistance mechanism, and the plasticity between the multiple resistance mechanisms will restrict the effectiveness of therapies targeting a single node of the oncogenic signaling network. SHP2 (Src homology 2 domain-containing phosphatase) is a phosphatase that mediates the signaling of multiple RTKs and is required for full activation of the MAPK pathway. Here we report IACS-13909 - a specific and potent allosteric inhibitor of SHP2 - suppresses the signaling of RTK/MAPK pathway. IACS-13909 potently impedes the proliferation of tumors with a broad spectrum of RTKs as the oncogenic driver. Importantly, in NSCLC models with acquired resistance to osimertinib, IACS-13909 administered as a single agent or in combination with osimertinib potently reduces tumor cell proliferation in vitro and in vivo. Together, our findings provide preclinical evidence for using a SHP2 inhibitor as a therapeutic strategy in acquired EGFR inhibitor-resistant NSCLC. Currently, a compound that potently inhibits SHP2 has been selected as the clinical development candidate and is undergoing IND-enabling studies with a projected first-in-human target of early 2020.

Citation Format: Yuting Sun, Brooke A Meyers, Sarah B Johnson, Angela L Harris, Barbara Czako, Jason B Cross, Paul G Leonard, Faika Mseeh, Maria E Di Francesco, Connor A Parker, Qi Wu, Christopher A Bristow, Jason P Burke, Caroline C Carrillo, Christopher L Carroll, Qing Chang, Ningping Feng, Sonal Gera, Gao Guang, Justin Kwang-Lay Huang, Yongying Jiang, Zhijun Kang, Jeffrey J Kovacs, Xiaoyan Ma, Pijus K Mandal, Timothy McAfoos, Robert A Mullinax, Michael D Peoples, Vandhana Ramamoorthy, Sahil Seth, Erika Suzuki, Christopher Conrad Williams, Simon S Yu, Andy M Zuniga, Giulio F Draetta, Joseph R Marszalek, Timothy P Heffernan, Nancy E Kohl, Philip Jones. Discovery of IACS-13909, an allosteric SHP2 inhibitor that overcomes multiple mechanisms underlying osimertinib resistance [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C036. doi:10.1158/1535-7163.TARG-19-C036

Author Correction: Mutations in the SWI/SNF complex induce a targetable dependence on oxidative phosphorylation in lung cancer

In the version of this article originally published, information regarding several funding sources was omitted from the Acknowledgements section. The following sentences should have been included: "This work was supported by the generous philanthropic contributions to The University of Texas MD Anderson Lung Cancer Moon Shots Program, the UT Lung SPORE 5 P50 CA07090, and the MD Anderson Cancer Center Support Grant P30CA01667. V.P is supported by R01CA155196-01A1 from the National Cancer Institute." Also, reference 18 was incorrect. The original reference was: Kim, E. S. et al. The BATTLE trial: personalizing therapy for lung cancer. Cancer Discov. 1, 44-53 (2011). It should have been: Papadimitrakopoulou, V. et al. The BATTLE-2 study: a biomarker-integrated targeted therapy study in previously treated patients with advanced non-small-cell lung cancer. J Clin. Oncol. 34, 3638-3647 (2016). The errors have been corrected in the HTML and PDF versions of this article.

Abstract LB-124: Promoting an anti-tumor immune environment with a novel, exquisitely selective CSF1R inhibitor

Tumor-associated macrophages (TAMs) are critical drivers of tumor progression and immunosuppression within the tumor microenvironment. The dominant TAM phenotype is broadly characterized as harboring M2-like macrophage properties, which are anti-inflammatory and pro-tumor, as opposed to M1-like macrophages, which possess tumoricidal and pro-inflammatory characteristics. The dependence of M2 TAMs on CSF1 receptor (CSF1R) kinase signaling has made CSF1R a desirable therapeutic target, and the need for highly selective therapies for use in combinations. Through an extensive medicinal chemistry campaign, we identified a series of orally bioavailable, highly potent, exquisitely selective inhibitors of CSF1R (IC50 < 10 nM) with excellent pharmacologic properties that are appropriate for evaluation as a cancer therapy. The aim of our study was to assess the biological impact of our lead CSF1R inhibitor (CSF1Ri) on macrophage populations and the consequent effect on T effector cells. In vitro biochemical activity was evaluated in various kinase assays comparing our CSF1Ri to BLZ945. The compound was evaluated using syngeneic murine models of colorectal cancer (MC38) and pancreatic adenocarcinoma (PANC02). Tumors were immune profiled using NanoString, immunohistochemistry and flow cytometric analysis establishing that there was a depletion of macrophages and a reduction in the relative amount of M2+ (CD206+MHCII-) cells, with a concomitant increase in M1+ (MHCII+CD206-) cells. Myeloid-derived suppressor cells (MDSCs), CD4, and CD8 cell infiltration were also altered with an elevation of cytotoxic immune cells. In conclusion, we have identified and characterized a novel potent and selective inhibitor of CSF1R with highly favorable PK/PD properties, that compares favorably to BLZ945. We also have clear evidence that our novel CSF1R inhibitors modulates TAM infiltration and phenotype altering the immune cell milieu toward a more favorable anti-tumor environment.

Citation Format: Erika Suzuki, Jeffrey J. Kovacs, Nakia D. Spencer, Sonal Sonal, Ningping Feng, Angela L. Harris, Robert A. Mullinax, Andy M. Zuniga, Sarah B. Johnson, Mikhila Mahendra, Tin Oo Khor, Faika Mseeh, Zhen Liu, Jason P. Burke, Keith Mikule, Martin Tremblay, Timothy P. Heffernan, Philip Jones, Barbara Czako, Joseph R. Marszalek. Promoting an anti-tumor immune environment with a novel, exquisitely selective CSF1R inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-124.

Mutations in the SWI/SNF complex induce a targetable dependence on oxidative phosphorylation in lung cancer

Lung cancer is a devastating disease that remains a top cause of cancer mortality. Despite improvements with targeted and immunotherapies, the majority of patients with lung cancer lack effective therapies, underscoring the need for additional treatment approaches. Genomic studies have identified frequent alterations in components of the SWI/SNF chromatin remodeling complex including SMARCA4 and ARID1A. To understand the mechanisms of tumorigenesis driven by mutations in this complex, we developed a genetically engineered mouse model of lung adenocarcinoma by ablating Smarca4 in the lung epithelium. We demonstrate that Smarca4 acts as a bona fide tumor suppressor and cooperates with p53 loss and Kras activation. Gene expression analyses revealed the signature of enhanced oxidative phosphorylation (OXPHOS) in SMARCA4 mutant tumors. We further show that SMARCA4 mutant cells have enhanced oxygen consumption and increased respiratory capacity. Importantly, SMARCA4 mutant lung cancer cell lines and xenograft tumors have marked sensitivity to inhibition of OXPHOS by a novel small molecule, IACS-010759, that is under clinical development. Mechanistically, we show that SMARCA4-deficient cells have a blunted transcriptional response to energy stress creating a therapeutically exploitable synthetic lethal interaction. These findings provide the mechanistic basis for further development of OXPHOS inhibitors as therapeutics against SWI/SNF mutant tumors.

Subgroup of reproductive functions of progesterone mediated by progesterone receptor-B isoform

Progesterone regulates reproductive function through two intracellular receptors, progesterone receptor-A (PR-A) and progesterone receptor-B (PR-B), that arise from a single gene and function as transcriptional regulators of progesterone-responsive genes. Although in vitro studies show that PR isoforms can display different transcriptional regulatory activities, their physiological significance is unknown. By selective ablation of PR-A in mice, we show that the PR-B isoform modulates a subset of reproductive functions of progesterone by regulation of a subset of progesterone-responsive target genes. Thus, PR-A and PR-B are functionally distinct mediators of progesterone action in vivo and should provide suitable targets for generation of tissue-selective progestins.