bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract P106: Reprogramming regulatory T cells (Treg) using a MALT1 inhibitor for cancer therapy
Authors: Keller Peter , Mazo Irina , Gao Yun , Reddy Vijayapal , Caballero Francisco , Kazer Sam , Miller Dannah , Gianani Roberto , Marvin James E. , Stephens Bret , Beatty Gregory L. , von Andrian Ulrich H. , Mempel Thorsten R.
Published: December 2021

Background Despite transforming effects of immune checkpoint blockade (ICB) therapy, objective response rates are low for most solid tumors. In the tumor microenvironment (TME), regulatory T cells are functionally unstable, likely due to changes in Treg metabolism seen in the tumor milieu. Destabilized Treg are susceptible to reprogramming wherein they can be induced to lose their immunosuppressive function and to secrete interferon-gamma (IFN-g). Thus, Treg reprogramming offers a novel strategy to sensitize unresponsive tumors to ICB. Notably, blockade of MALT1 protease induces Treg reprogramming in the TME but without affecting Treg in healthy tissue. MPT-0118, an orally dosed MALT1 inhibitor, was developed to reprogram Treg in the TME and is currently being assessed in patients with advanced tumors. Approach Treatments included MPT-0118 and anti-PD-1. In vivo studies in mice assessed anti-tumor effects using D4M.3A, B16F10, and MC38 syngeneic tumors. Human and mouse tumor tissues were evaluated for Treg reprogramming by in situ hybridization or flow cytometry. Studies in rats and dogs assessed pharmacokinetics and safety. Results MPT-0118 demonstrated dose-dependent in vivo anti-tumor activity. Consistent with the hypothesis that Treg reprogramming supports anti-tumor immunity by initiating IFN-g-driven tumor inflammation, the effect was strongest in combination with anti-PD-1 and in models that are not responsive to ICB alone. MPT-0118-treated tumors showed an increase in IFN-g-secreting Treg, associated with decelerated tumor growth. Ex vivo, MPT-0118 induced Treg reprogramming in tumors resected from patients with colorectal and endometrial cancers. While MPT-0118 caused Treg to produce IFN-g, no changes in the frequencies of Treg circulating in blood were detected in rats. Modeling of the human effective dose and toxicology studies demonstrate a >2x therapeutic window in patients. Conclusions MPT-0118 Treg reprogramming represents a novel strategy with the potential to improve responses to ICB therapy in solid tumors. A Phase 1/1b dose-escalation and cohort-expansion clinical trial evaluating MPT-0018 is underway.

Citation Format: Peter Keller, Irina Mazo, Yun Gao, Vijayapal Reddy, Francisco Caballero, Sam Kazer, Dannah Miller, Roberto Gianani, James E. Marvin, Bret Stephens, Gregory L. Beatty, Ulrich H. von Andrian, Thorsten R. Mempel. Reprogramming regulatory T cells (Treg) using a MALT1 inhibitor for cancer therapy [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P106.
Abstract P110: Neandertal introgressions contribute to upper aero-digestive tract tumor patient survival and identify patients who may benefit from STING agonist treatment
Authors: Gualberto Antonio , Chen Tenghui , Scholz Catherine , Luke Jason
Published: December 2021

Background: Admixture of archaic (Neandertal and Denisova) and ancestral genes enhanced natural immunity during out of Africa migrations and modulates modern susceptibility to autoimmunity and cancer. We investigated a series of functional interactions between archaic and ancestral STING1 and TLR genes to identify vulnerabilities that could be addressed by STING agonist therapy. Methods: Gene variants from 10,389 cancer patients (pts) were obtained from TCGA. Archaic sequences were accessed using UCSD genome browser 410. Linkage disequilibrium was investigated using LDlink v5.0. Patient 1 was treated within NCT04144140. Results: STING1 variants were overrepresented in gastroesophageal cancer pts. V48V (rs7447927-C>G) with GWAS of lower rate of Asian esophageal cancer was in linkage disequilibrium with the reference alleles of the partially active HAQ and REF variants, and with rs13153461, present in Neandertal sequences. STING1 rs7447927-G was also associated with HLA A*24:02 (p<0.001), A*02:06 (p=0.01), and A*31:01 (p=0.02), of Neandertal origin. We then investigated a potential epistasis between STING1 rs7447927-G and TLR variants associated with decreased H. pylori prevalence: Neandertal-like TLR10 I775V (rs4129009) and ancestral TLR6 S249P (rs5743810). No independent prognosis was identified in 32 TCGA legacy studies; however, in upper aerodigestive (oral cavity, oropharynx, esophageal, gastric, biliary tract) tumor pts who carried reference/heterozygous TLR6 S249P and/or reference TLR10 I775, Neandertal-associated STING1 rs7447927-G zygosity was a strong predictor of survival. Hazards ratio for rs7447927-GG vs GC (4.8 vs 2.7 yrs. median survival), and GG vs CC (4.8 vs 1.8 yrs.) were respectively 0.71 and 0.53, N=713, p=0.0003. Patient 1 was a 75 yr.-old male esophageal cancer pt with GERD, Barrett’s esophagus and TLR6 S249/STING1 rs7447927-GC, who was progressing from anti-PD1 and chemotherapy and received 75 microg intra-tumoral injections of the STING agonist E7766. Non treatment-related grade 2 events of anemia and hyponatremia, serum IFNbeta and IP10 levels induction, 20% tumor size reduction including abscopal effects, and 6.3 months PFS benefit were observed. Conclusion: Genotyping of STING1, TLR6-10 variants could contribute to identify pts who may benefit from E7766 treatment.

Citation Format: Antonio Gualberto, Tenghui Chen, Catherine Scholz, Jason Luke. Neandertal introgressions contribute to upper aero-digestive tract tumor patient survival and identify patients who may benefit from STING agonist treatment [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P110.
Abstract P111: Therapeutic KRASG12C inhibition alleviates KRAS-driven immunosuppression
Authors: Mugarza Edurne , Van Maldegem Febe , Boumelha Jesse , Moore Chris , Rana Sareena , Sopena Miriam Llorian , East Phil , Arcas Miriam Molina , Downward Julian
Published: December 2021

Therapeutic KRASG12C inhibitors may substantially improve KRAS-mutant cancer patient care, considering the encouraging clinical data emerging from ongoing clinical trials. Since oncogene-targeting therapies often lead to resistance, the development of combinatorial therapies will be of utmost importance to achieve long-lasting tumour control. Given the known immunosuppressive role of KRAS, clinical trials investigating the combination of KRASG12C inhibitors with immune checkpoint blockade are currently underway for NSCLC patients. Here, we show that KRASG12C inhibition using MRTX1257 alleviates KRAS-driven immune suppression, through a myriad of mechanisms including the augmentation of tumour cell-intrinsic interferon responses. Despite harbouring a large number of somatic mutations, orthotopic 3LL (KRASG12CDNRAS) tumours are able to evade anti-tumour immune responses. Combining multicolour flow cytometry, RNA sequencing and imaging mass cytometry, we observed significantly increased T cell activation and infiltration after MRTX1257 treatment in addition to enhanced antigen presentation cells and gene sets, and reduced myeloid cells, creating an immune permissive microenvironment in these lung tumours. Despite these profound changes, combination of KRASG12C inhibitors and anti-PD-(L)1 antibodies fail to show synergism in our model, in contrast with Amgen’s published data using an immunogenic model of colorectal cancer. This data suggests that a pre-existing anti-tumour immunity may be crucial for clinical responses to KRAS inhibitors and immune checkpoint blockade combinations. Henceforth, ongoing clinical trials investigating this approach will likely only benefit a subset of patients and further research will be needed to examine novel therapeutic approaches and combinations for refractory patients.

Citation Format: Edurne Mugarza, Febe Van Maldegem, Jesse Boumelha, Chris Moore, Sareena Rana, Miriam Llorian Sopena, Phil East, Miriam Molina Arcas, Julian Downward. Therapeutic KRASG12C inhibition alleviates KRAS-driven immunosuppression [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P111.
Abstract P137: SGLT2 inhibition improves BYL719-induced hyperglycemia and hyperinsulinemia in rat pre-clinical models
Authors: Schnell Christian R. , Wyss Daniel , Tinetto Walter , Ferrat Thomas , Gao Jiaping , Darrell Panza , Gold Josh , Beaulieu Valerie , Diener John , Fritsch Christine
Published: December 2021

Background In phase III SOLAR-1 trial (NCT02437318), the PI3K alpha selective inhibitor alpelisib (ALP) + fulvestrant significantly improved progression-free survival vs. fulvestrant alone in patients with HR+/HER2- advanced breast cancer with PIK3CA mutations. Hyperglycemia is an on-target adverse effect of ALP that led to 6% of patient discontinuation in the ALP arm. Recently, Sodium-glucose co-transporter 2 (SGLT2) inhibition was reported to reduce PI3K inhibition-induced glucose and insulin increase. For 6 SOLAR-1 patients, the addition of an SGLT2 inhibitor to metformin (MET) and ALP stabilized blood glucose levels, allowing them to continue ALP treatment. Methods Brown Norway (BN) rat and Rat1-myr-p110α tumor bearing nude rat in vivo models were used to further investigate the degree of glucose and insulin control achievable upon treatment with ALP and a SGLT2 inhibitor dapagliflozin (DAPA) +/- MET and effects on ALP tolerability and efficacy. Results In both rat models tested, the addition of DAPA to ALP nearly suppressed ALP-induced hyperglycemia, was associated with insulin level reduction and insulin sensitivity improvement and no signs for ketoacidosis upon single agent (S.A) nor combination were observed under fed conditions. ALP S.A efficacy in the Rat1-myr-p110α tumor bearing nude rats was maintained when used in combination with DAPA and there was no influence of DAPA on ALP-induced body weight loss (BWL). In BN rats, when combining MET with ALP, a delay in blood glucose reduction was observed vs. DAPA + ALP combination. The triple combination of MET + DAPA + ALP improved further blood glucose levels reduction with the same kinetic as DAPA + ALP. MET + DAPA + ALP triple combination was more effective in reducing plasma insulin levels when compared to MET + ALP or DAPA + ALP double combinations. All combinations tested with MET slightly increased BYL719-induced BWL in BN rats. Conclusions SGLT2 inhibitors such as DAPA significantly reduced hyperglycemia and improved hyperinsulinemia induced by ALP in rat models without further BWL induced by ALP. These results warrant further clinical investigation of adding SGLT2 inhibitors +/- metformin to treat ALP-induced hyperglycemia.

Citation Format: Christian R. Schnell, Daniel Wyss, Walter Tinetto, Thomas Ferrat, Jiaping Gao, Panza Darrell, Josh Gold, Valerie Beaulieu, John Diener, Christine Fritsch. SGLT2 inhibition improves BYL719-induced hyperglycemia and hyperinsulinemia in rat pre-clinical models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P137.
Abstract P157: Targeting Trop2 for treatment of prostate and breast cancer
Authors: Stoyanova Tanya
Published: December 2021

Background: Prostate cancer and breast cancer are the most commonly diagnosed non-skin cancers and the second leading cause of cancer related mortalities in men and women respectively in the United States. Fifteen percent of breast cancer is TNBC characterized with lack of receptors for estrogen, progesterone, and HER-2/neu making it resistant to hormone therapies and therapies targeting estrogen, progesterone, and HER-2/neu signaling. The first line of treatment for men with advanced prostate cancer is androgen depravation therapy. While initial responses are observed, unfortunately, the disease frequently recurs as a lethal metastatic form referred to as castration-resistant prostate cancer (CRPC). We recently identified that the cell surface receptor, Trop2, is a new regulator of TNBC and CRPC. We demonstrated that Trop2 is highly expressed in CRPC and TNBC. In this study, we set out to test the therapeutic potential of new fully humanized human anti-Trop2 antibody fragments in CRPC and NEPC. Methods: We have generated new human anti-Trop2 antibody fragments. Lentiviral infection was used to generate prostate and breast cancer cell lines with over-expression of Trop2 and knock-down of Trop2. In vivo functional assays were performed including subcutaneous xenograft growth and metastasis. Results: High protein levels of Trop2 are observed in metastatic CRPC and TNBC. Furthermore, loss of Trop2 significantly delays growth, migration and invasion of prostate and breast cancer cells in vitro and delays tumor growth and metastasis of prostate and breast cancer in vivo. Overexpression of Trop2 enhances tumor growth and metastasis of prostate cancer cells and drives CRPC. We generated new fully humanized human anti-Trop2 antibody fragments that have therapeutic efficacy in preclinical models of prostate and breast cancers. Conclusions: In a previous study, we identified cell surface receptor, Trop2, as a novel driver of metastatic CRPC. Herein, our new findings reveal that Trop2 represents a promising therapeutic target for prostate, breast, and potentially other epithelial cancers. We identified lead antibody candidates that bind to human Trop2 protein with high affinity and stability. Furthermore, our lead anti-Trop2 Abs significantly delay the tumors growth in CRPC and TNBC without measurable toxicity and provide new therapeutic strategy for metastatic CRPC and TNBC.

Citation Format: Tanya Stoyanova. Targeting Trop2 for treatment of prostate and breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P157.
Abstract P175: Investigating inositol polyphosphate-4-phosphatase, type II (INPP4B) signaling and role in acute myeloid leukemia
Authors: Chen Keyue , Genc Gizem E. , Woolley John F. , Lee Daniel K.C. , Botelho Roberto J. , Salmena Leonardo
Published: December 2021

Acute myeloid leukemia (AML) is an aggressive clonal stem cell disorder characterized by invasion of bone marrow, impaired hematopoiesis and accumulation of functionally immature myeloblasts. Our previous studies demonstrated that the expression level of the lipid phosphatase, INPP4B, is associated with poor outcomes in AML. To gain an understanding of the role of Inpp4b in AML progression, we performed RNA sequencing on Inpp4b+/+ and Inpp4b−/− MLL-AF9 leukemias. Analysis of RNA sequencing data revealed that a disproportionately large number of lysosomal gene transcripts are decreased in Inpp4b−/− leukemias; these include cathepsins and lysosomal specific proteases responsible for proteolysis. This discovery provided evidence supporting a potential role for INPP4B in the lysosomal pathway. To validate these findings, immunofluorescence staining of the lysosomal protein LAMP1 was performed, which revealed a greater number of lysosomes in U2OS cells overexpressing INPP4B, and a decrease in lysosome number upon siRNA knockdown of INPP4B. Subsequently the DQ-BSA staining was used to assess INPP4B’s effect on lysosomal function. In both U2OS and the leukemia cells, we observed that INPP4B expression is positively associated with the proteolytic activity of lysosomes. Currently we are testing the role of INPP4B expression on sensitivity to lysosomal inhibitors; Lys05, Chloroquine, and Mefloquine. Overall, we aim to uncover how INPP4B expression in AML controls lysosomal mechanisms and biology and to test putative therapeutic strategies to exploit this pathway.

Citation Format: Keyue Chen, Gizem E. Genc, John F. Woolley, Daniel K.C. Lee, Roberto J. Botelho, Leonardo Salmena. Investigating inositol polyphosphate-4-phosphatase, type II (INPP4B) signaling and role in acute myeloid leukemia [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P175.
Abstract P176: Discovery and development of novel covalent inhibitors of the YAP-TEAD transcription activity
Authors: Guo Shirley , Huang Cindy , Begley C. Glenn , Bishop Michael J. , Cao Ping
Published: December 2021

TEAD (TEA domain transcription factor) is a transcription factor. As a major effector of the Hippo signaling pathway, TEAD is reported to be responsible for cell proliferation, apoptosis, and stem cell self-renewal. Emerging evidence has shown that TEADs play a prominent role in the development, progression, and metastasis of cancers such as mesothelioma, liposarcoma, pancreatic, etc. Small-molecule inhibitors of TEADs could be a novel targeted therapy for multiple cancers. Using its proprietary chemoproteomic platform IMTACTM (Isobaric Mass Tagged Affinity Characterization), BridGene has screened its unique covalent library against live-cell proteomes. Three distinct series of hits, with MCS Tanimoto Coefficients at ~0.3 between any two series, were identified for TEAD proteins with nanomolar affinity and high proteomic selectivity. The covalent interactions between the hit and TEAD proteins were confirmed using orthogonal fluorescence-based experiments. Mass Spec analysis and mutagenesis experiments identified the site of modification within the central lipid (palmitate) binding pocket of TEAD1. Multiple novel and potent small molecule inhibitors were obtained with good druggability. Several functional assays were established to measure inhibition of TEAD-YAP transcription activity/disruption including Luciferase assay in MCF7-Luc, CTG (cell-titer Glo), and ELISA. When evaluated in vitro, BridGene’s TEAD inhibitors exhibited anti-proliferative properties against NF2-deficient mesothelioma cell lines (NCI-H226, NF2-/-) with low nM IC50, but had little effects on in NF2 wildtype cancer cell lines (NCI-H2452, NF2+/+) or HepG2 cell line. In an ELISA assay, BridGene’s small molecules can potently disrupt TEAD-YAP protein-protein interaction in cells. In MCF7-TEAD1 luciferase reporter cells, compounds showed single-digit nM potency in disrupting TEAD downstream gene expression. BridGene is developing covalent TEAD inhibitors to treat multiple cancers that are dependent on TEAD activity, including mesothelioma, cholangiocarcinoma, liposarcoma, pancreatic cancer, etc. With their high potency and proteomic selectivity, these TEAD inhibitors can potentially act as single-agent therapy, or work in combination with other care agents to treat multiple cancers.

Citation Format: Shirley Guo, Cindy Huang, C. Glenn Begley, Michael J. Bishop, Ping Cao. Discovery and development of novel covalent inhibitors of the YAP-TEAD transcription activity [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P176.
Abstract P178: RBM39 degradation leads to exceptional responses in high-risk neuroblastoma by targeting the spliceosome
Authors: Yang Jun
Published: December 2021

Genome-wide studies of thousands of human tumors have revealed dysregulated pre-mRNA splicing as a critical pathway in tumorigenesis, which may consequently create vulnerabilities for cancer cells. Indeed, C-MYC-dependent cancers are specifically susceptible to perturbation of spliceosome function. The MYC oncogenes (C-MYC, MYCN, and MYCL1), which are known transcriptional drivers of large numbers of genes, are among the most common genetic abnormalities in human cancer. We found that neuroblastoma, a MYC-driven cancer characterized by splicing dysregulation and spliceosomal dependency, requires splicing factor RBM39 for survival. Indisulam, a “molecular glue” that selectively recruits RBM39 to the CRL4-DCAF15 E3 ubiquitin ligase for proteasomal degradation, is highly efficacious against neuroblastoma, leading to exceptional responses in multiple high-risk disease models, without overt toxicity. Genetic depletion or indisulam-mediated degradation of RBM39 induces significant genome-wide splicing anomalies and cell death. Mechanistically, the dependency on RBM39 and high-level expression of DCAF15 determine the exquisite sensitivity of neuroblastoma to indisulam. Our data indicate that targeting the dysregulated spliceosome by precisely inhibiting RBM39, a vulnerability in neuroblastoma, is a valid therapeutic strategy. In summary, our study has validated the mechanism by which “molecular glues” targeting RNA binding proteins can be exploited for drug development in cancer, and has a broad impact on understanding of the splicing dependency of MYC-driven cancers and the identification of novel therapeutic approaches against them.

Citation Format: Jun Yang. RBM39 degradation leads to exceptional responses in high-risk neuroblastoma by targeting the spliceosome [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P178.
Abstract P182: VRK1 is a novel synthetic lethal target in VRK2-methylated glioblastoma
Authors: Shields Julie , Meier Samuel R. , Engel Justin , Bandi Madhavi , Dam Ferdinez Maria L. , Zhang Wenhai , Zhao Shan-chuan , Zhang Minjie , Choi Ashley , Yu Yi , Pan Xuewen , McMillan Brian , Williams Brett , Sjin Robert Tjin Tham , Whittington Douglas , Wilker Erik , Huang Alan , Li Fang , Emmanuel Natasha
Published: December 2021

Synthetic lethality — the genetic interaction that causes cell death when two genetic deficiencies co-occur but cell survival when each deficiency occurs alone — can be co-opted for cancer therapeutics. A pair of paralog genes is among the most straightforward synthetic lethal interactions by virtue of their redundant function in the cell. Here we demonstrate a paralog synthetic lethality by targeting VRK1 in VRK2-methylated glioblastoma multiforme (GBM). VRK2 is silenced by methylation in about two-thirds of GBM, an aggressive cancer with few available targeted therapies. Genetic knockdown of VRK1 in VRK2-null or VRK2-methylated cells leads to cell death via cell cycle arrest in G2M and subsequent DNA damage. The lethality is dependent on the kinase activity of VRK1 and is rescued by ectopic VRK2 expression. Knockdown of VRK1 leads to robust tumor growth inhibition in VRK2-methylated glioblastoma xenografts in vivo. These results suggest that inhibiting VRK1 kinase activity could be a viable cancer therapeutic in VRK2-methylated glioblastoma.

Citation Format: Julie Shields, Samuel R. Meier, Justin Engel, Madhavi Bandi, Maria L. Dam Ferdinez, Wenhai Zhang, Shan-chuan Zhao, Minjie Zhang, Ashley Choi, Yi Yu, Xuewen Pan, Brian McMillan, Brett Williams, Robert Tjin Tham Sjin, Douglas Whittington, Erik Wilker, Alan Huang, Fang Li, Natasha Emmanuel. VRK1 is a novel synthetic lethal target in VRK2-methylated glioblastoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P182.
Abstract P184: Anti-tumor efficacy of an MMAE conjugated antibody targeting cell surface TACE/ADAM17-cleaved Amphiregulin in breast cancer
Authors: Lofgren Kristopher A. , Sreekumar Sreeja , Jenkins Edmund C. , Ernzen Kyle J. , Kenny Paraic A.
Published: December 2021

The Epidermal Growth Factor Receptor ligand, Amphiregulin, is a key proliferative effector of estrogen receptor signaling in breast cancer and also plays a role in other malignancies. Amphiregulin is a single-pass transmembrane protein proteolytically processed by TACE/ADAM17 to release the soluble EGFR ligand, leaving a residual transmembrane stalk that is subsequently internalized. Here, we report the development of an antibody drug conjugate, GMF-1A3-MMAE, targeting an AREG neo-epitope revealed following ADAM17-mediated cleavage. The antibody does not interact with uncleaved Amphiregulin, providing a novel means of targeting cells with high rates of Amphiregulin shedding. Using fluorescent dye conjugation, we demonstrated that the antibody is internalized by cancer cells in a manner dependent on the presence of cell surface cleaved Amphiregulin. Antibodies conjugated with monomethyl auristatin E (MMAE) were cytotoxic in vitro and induced rapid regression of established breast tumor xenografts in immunocompromised mice. We further demonstrate that these antibodies recognize the Amphiregulin neo-epitope in formalin fixed paraffin embedded tumor tissue, suggesting their utility as a companion diagnostic for patient selection.

Citation Format: Kristopher A. Lofgren, Sreeja Sreekumar, Edmund C. Jenkins, Kyle J. Ernzen, Paraic A. Kenny. Anti-tumor efficacy of an MMAE conjugated antibody targeting cell surface TACE/ADAM17-cleaved Amphiregulin in breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P184.
Abstract P215: The MDM2 inhibitor milademetan induces synthetic lethality in GATA3 mutant, ER positive breast cancer
Authors: Tirunagaru Vijaya G. , Bianco Gaia , Ng Charlotte K. Y. , Marangoni Elisabetta , Piscuoglio Salvatore , Bidard François-Clément , Doebele Robert C.
Published: December 2021

GATA3 is mutated, predominantly via frameshift (fs) mutations, in 15-18% of estrogen receptor (ER)-positive breast cancers and GATA3 mutations define a subset of patients with poor response to hormonal therapy. Importantly, GATA3 mutations are not currently targetable. Computational analysis of the data from the large-scale, deep RNAi screen project DRIVE led to the identification of MDM2 as a synthetic lethal partner in a GATA3 mutant ER+ breast cancer cell line. The objective of this study was to evaluate the activity of milademetan (RAIN-32), an orally available, small molecule inhibitor of MDM2 in GATA3 mutant ER+ breast cancer. Here, we evaluated the effect of MDM2 silencing in ER+, GATA3 mutant breast cancer cell line MCF-7 harboring a loss-of-function mutation (p.D335Gfs) that has been recurrently observed in breast cancer patients and tested the antitumoral activity of milademetan in vitro (MCF-7 cell line) ex vivo (patient derived organoids; PDO) and in vivo (cell line-derived xenograft and patient-derived xenograft (PDX) models). Additionally, we hypothesized that the synthetic lethality is p53 dependent and to this aim we explored the p53 dependent effects of milademetan inhibition by determining the effect of MDM2 loss in the absence of p53 and analyzing the expression of p53-target genes. Finally, we evaluated the impact of GATA3 mutations on survival in breast cancer using TCGA and AACR Genie datasets.MDM2 silencing significantly reduced cell proliferation in MCF-7. This effect was shown to be p53 dependent as p53 knockdown reversed the effect of MDM2 loss. MCF-7 cell line was also sensitive to milademetan in vitro. Finally, we tested milademetan in ER+ breast cancer models (PDO and a fulvestrant-resistant PDX) harboring a GATA3fs mutation and wild type TP53. Treatment of these models displayed dose-dependent anti-tumor activity to milademetan ex vivo and in vivo. Sequencing data analyses of the publicly available datasets revealed lower survival in GATA3 mutant breast cancer and mutual exclusivity with TP53 mutations. In conclusion, MDM2 deficiency leads to synthetic lethality in GATA3 mutant breast cancers. Milademetan shows evidence of antitumor activity in genetically selected ER+ breast tumors with GATA3 mutations. These data provide evidence for clinical exploration of milademetan in ER+, GATA3 mutant breast cancer refractory to current therapies.

Citation Format: Vijaya G. Tirunagaru, Gaia Bianco, Charlotte K. Y. Ng, Elisabetta Marangoni, Salvatore Piscuoglio, François-Clément Bidard, Robert C. Doebele. The MDM2 inhibitor milademetan induces synthetic lethality in GATA3 mutant, ER positive breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P215.
Abstract P217: The next generation PARP inhibitor AZD5305 is active in a broad range of pre-clinical models of ovarian cancer
Authors: Dellavedova Giulia , Decio Alessandra , Staniszewska Anna , Leo Elisabetta , Giavazzi Raffaella , Bani Maria Rosa
Published: December 2021

Since the approval of poly (ADP-ribose) polymerase inhibitors (PARPi) for BRCA-mutated ovarian cancer patients, different PARPi have been developed and have shown efficacy in homologous recombination deficient (HRD) tumours. These first-generation drugs inhibit both PARP1 and PARP2 (as well as other PARP family members) and present undesirable adverse effects, such as haematological and intestinal toxicity, that restricted their use especially in combination with already poorly tolerated chemotherapeutic agents. Here, patient-derived ovarian cancer xenografts (OC-PDXs) were used i) to evaluate the dose response efficacy of AZD5305, a next generation, potent and selective PARP1 inhibitor and ii) to investigate the effect of the combination with carboplatin, a standard-of-care treatment for ovarian cancer patients. AZD5305 was administered orally (po) once daily (QD) for 8 weeks as monotherapy (0.1, 1 and 10 mg/kg) and in combination with carboplatin (CPT) dosed intravenously (35 mg/kg; Q7x4). Two BRCA1 mutated (HOC106 and HOC107) and a BRCA wild-type (HOC84) OC-PDXs (all TP53 mutated) were implanted subcutis and the effect of treatments on tumour growth evaluated. AZD5305 dosed at 0.1, 1 and 10 mg/kg to mice bearing HOC106 tumours, inhibited tumours growth in a dose dependent manner. Administered in combination at 0.1 and 1 mg/kg, AZD5305 potentiated the effect of carboplatin, causing a significant and sustained regression of HOC106 tumours. The anti-tumour efficacy was also evident against the PARPi-resistant OC-PDX HOC107, whereby the tumour growth was inhibited by AZD5305 at 1 and 10 mg/kg dose. Combined with carboplatin, AZD5305 stabilized the growth of HOC107 tumours at doses as low as 0.1 mg/kg that on its own was not effective. As expected, none of the treatments affected the growth of the BRCA wild-type HOC84 (PARPi and carboplatin resistant OC-PDX). Overall, AZD5305 a next generation PARP1-selective inhibitor and trapper, shows improved efficacy and tolerability in combination with chemotherapy compared to first generation, PARP1/2 inhibitors, making it a promising clinical candidate for the treatment of ovarian cancer.

Citation Format: Giulia Dellavedova, Alessandra Decio, Anna Staniszewska, Elisabetta Leo, Raffaella Giavazzi, Maria Rosa Bani. The next generation PARP inhibitor AZD5305 is active in a broad range of pre-clinical models of ovarian cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P217.
Abstract P231: Multigenomic characterization of context-dependent alternative splicing in normal and neoplastic cells
Authors: McMillan Elizabeth A. , Sriram Krishna , Creger Emily , Merkwirth Carsten , Pippa Raffaella , Pedraza Melinda , Do Long , Deshmukh Vishal , Bossard Carine , White Michael A.
Published: December 2021

Alternative pre-mRNA splicing (AS) supports the dynamic and regulated diversification of cells by allowing the production of multiple distinct proteins from individual genes. Dysregulated AS is commonly associated with human malignancies, producing pathological proteomes that underpin disease initiation, progression, and emergence of therapy resistance. The CDC2-like kinases (CLKs) and dual-specificity tyrosine-regulated kinases (DYRKs) are thought to govern the efficiency and specificity of AS by directly phosphorylating serine/arginine-rich splicing factors (SRSFs) and thereby influencing pre-mRNA splice junction selection. Cirtuvivint (SM08502) is a first-in-class small molecule ATP-competitive inhibitor of CLK/DYRK kinases. To directly evaluate the contribution of these kinases to AS profiles, changes in AS following treatment with cirtuvivint followed by high-depth RNAseq analysis across >25 cell lines representing 7 tumor lineages were evaluated. Both baseline and drug-induced changes in AS events (ASEs) were measured using a multivariate analysis of transcript splicing (rMATS). Pan-CLK/DYRK inhibition was found to affect a minority of baseline ASEs, leaving the majority of spliceosome activity intact in all samples. However, the magnitude and quantity of detected drug-induced alterations were larger in a sample of tumor cells from a patient compared with adjacent non-tumorigenic cells. Moreover, most ASEs sensitive to pan-CLK/DYRK inhibition were tumor type-specific irrespective of selective presence at the gene level. Multi-omics data integration revealed sensitivity to cirtuvivint was associated with alterations in splicing genes and that drug-induced ASEs were significantly associated with disease-promoting biology across lineage and oncogenic driver contexts. Perturbed splicing of the AR-V7 variant in treatment-resistant prostate cancer and MDM2 in p53 wild-type cancers were prominent examples. These observations indicate vulnerabilities to CLK-DYRK regulated splicing span a wide range of oncogenic contexts with potential to be therapeutically addressed with pan CLK/DYRK inhibitors.

Citation Format: Elizabeth A. McMillan, Krishna Sriram, Emily Creger, Carsten Merkwirth, Raffaella Pippa, Melinda Pedraza, Long Do, Vishal Deshmukh, Carine Bossard, Michael A. White. Multigenomic characterization of context-dependent alternative splicing in normal and neoplastic cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P231.
Abstract P242: Preclinical efficacy landscape of the pan-CLK/DYRK inhibitor Cirtuvivint (SM08502)
Authors: Bossard Carine , Creger Emily , McMillan Elizabeth A. , Merkwirth Carsten , Ibanez Maureen , Bhat Deepti , Stewart Josh , Eastman Brian , Mak Chi-Ching , Deshmukh Vishal , White Michael A.
Published: December 2021

A monumental challenge facing cancer therapy is the vast mechanistic diversity of tumors among and even within cancer patients. This severely limits the number of patients that respond to any given therapy and the durability of responses that do occur. Deep phenotypic profiling of almost 9000 patient samples indicates perturbation of alternative pre-mRNA splicing (AS) is often a root cause of cancer. This offers an extraordinary opportunity to restore health through normalization of AS in diseased tissue. The bottleneck to progress has been finding and drugging the right targets. The CLK/DYRK kinases modulate AS efficiency and specificity, and therefore, targeting them offers the potential to address this bottleneck. The isoquinoline cirtuvivint is a potent ATP-competitive inhibitor of the Cdc2-like kinases (CLK1-4) and the dual-specificity tyrosine phosphorylation-regulated kinases (DYRK1-4), with activity against only a minimal number of the remaining members of the CMGC-family kinases or the kinome as a whole. Cellular target engagement assays indicated biological IC50s below 0.06 μM across the CLK/DYRK target class. Thus, cirtuvivint has utility for robust chemical evaluation of the overarching contribution of CLK/DYRK family activity to tumor biology in general and context- dependent AS in particular. To help assess the breadth and depth of CLK/DYRK dependencies in human cancers, the consequences of pan-CLK/DYRK inhibition on growth and survival of 154 cancer cell line models, 46 PDX models, and 43 CDX models were tested. EC50s in cell viability assays ranged from 0.014 to 0.73 μM in culture with strong effects observed in subsets of cell lines across all lineages tested. Molecular profiles associated with high sensitivity to cirtuvivint included somatic mutations in the RBM10 splicing factor. Tumor growth inhibition assays with daily dosing at exposures about 2X below the MTD resulted in significant disease control (≥75% TGI) in 15/46 PDX and 18/43 CDX models. Together, these results indicate broad cancer relevance, at least in the preclinical setting, and are consistent with a common reliance on CLK/DYRK-dependent alternative splicing among otherwise highly mechanistically heterogeneous disease.

Citation Format: Carine Bossard, Emily Creger, Elizabeth A. McMillan, Carsten Merkwirth, Maureen Ibanez, Deepti Bhat, Josh Stewart, Brian Eastman, Chi-Ching Mak, Vishal Deshmukh, Michael A. White. Preclinical efficacy landscape of the pan-CLK/DYRK inhibitor Cirtuvivint (SM08502) [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P242.
Abstract P245: Synergistic effect of combination of pemigatinib with enfortumab vedotin (EV) in human bladder cancer models
Authors: Hess Rodrigo A. , Truong Lisa , Chadderton Antony , Frascella Michelle , Hall Leslie , Koblish Holly
Published: December 2021

Bladder cancer is among the most prevalent cancers worldwide, with urothelial carcinoma accounting for approximately 90% of cases. Until recently, poor overall survival after chemotherapy combined with immune checkpoint blockade therapies for patients with advanced urothelial carcinoma highlighted the need for new therapies. Although data supports the use of targeted therapies, such as FGFR inhibitors, recent advances in the treatment of bladder cancer are changing the landscape. Enfortumab vedotin (EV) is an antibody drug conjugate (ADC) consisting of an anti-Nectin-4 antibody conjugated to monomethyl auristatin E, which specifically delivers the auristatin payload to Nectin-4 high-expressing urothelial carcinomas. While activity and durability of response from both monotherapy trials as well as combination with pembrolizumab are favorable, additional treatment options might be required for either patients not responding to treatment or those who might develop resistance. Importantly, FGFR activation through rearrangement or mutation is frequently found in the luminal papillary subtype which also expresses high levels of Nectin-4. Thus, we sought to test the potential of combining pemigatinib and EV in models of human bladder cancer which express both activated FGFR3 and Nectin-4. Our initial analysis show that FGFR3 mutant tumors express high levels of Nectin-4. We further demonstrated that two bladder cancer cell lines RT112/84 (FGFR3-TACC3 fusion) and UM-UC-14 (FGFR3S249C) are sensitive to both pemigatinib and EV in vitro and in vivo. Notably, synergistic anti-tumor effects were observed when pemigatinib was combined with EV in vivo. In addition, combination of pemigatinib with EV significantly improved overall survival when compared to single treatments in these models. Altogether, our data strongly suggest a potential for combination of these therapies in the clinic.

Citation Format: Rodrigo A. Hess, Lisa Truong, Antony Chadderton, Michelle Frascella, Leslie Hall, Holly Koblish. Synergistic effect of combination of pemigatinib with enfortumab vedotin (EV) in human bladder cancer models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P245.
Abstract P262: Automated nerve identification in histopathology slides enables comprehensive analysis of innervation in cancer and tumor neurobiology
Authors: Miller Alison R. , Krasnonosenkikh Daniel , Thanawala Monica , Huang Kai Chih , Thomas George V. , Lantermann Alexandra B. , Dai Hongyue , Sadaghiani Masoud , Wagner John A. , Huang Pearl
Published: December 2021

Linking features of the tumor microenvironment (TME) to patient outcome is ambitious yet crucial to understand cancer progression and prognosis in order to develop new therapies. The current method to assess histopathological images is visual inspection by a professional, generally a pathologist. While this is an effective approach for diagnosis, it does not scale well for discovery biology and population-based studies for drug discovery purposes. An automated approach would allow for a more rapid, systematic, and comprehensive analysis of several morphological features of the TME by taking advantage of thousands of already existing slides within databases and biobanks. Recent studies have shown intriguing relationships between innervation in tumors (tumor exoneural biology) and patient outcomes. Here we present an automated tool that can detect and quantify nerve presence in tumors. We manually annotated a set of digital slides from The Cancer Genome Atlas (TCGA) in order to develop a deep learning model to quantify the presence of nerves in head and neck tumors stained with H&E. This tool is generalizable and was applied to identify patterns in the appearance of tumor-infiltrating lymphocytes (TILs) in and around tumors. It may be further applied to other structural features such as blood vessels in order to characterize and correlate these features within the TME in hundreds of images across cancer types. This enables integration of imaging features with multi-omics data to uncover potential biological pathways that are upregulated in groups with dense innervation compared to sparse innervation in cancer. The main advantage of this approach is the ability to utilize many public databases in which the features of interest can be correlated with reported patient comorbidities, treatments, and phenotypes. This platform-based methodology can be expanded to other disease areas and could ultimately provide valuable insight about exoneural biology and its role in disease physiology to identify new avenues for therapies.

Citation Format: Alison R. Miller, Daniel Krasnonosenkikh, Monica Thanawala, Kai Chih Huang, George V. Thomas, Alexandra B. Lantermann, Hongyue Dai, Masoud Sadaghiani, John A. Wagner, Pearl Huang. Automated nerve identification in histopathology slides enables comprehensive analysis of innervation in cancer and tumor neurobiology [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P262.
Abstract P263: Interaction between CD36 and FABP4 regulates the import and metabolism of fatty acid in breast cancer cells
Authors: Gyamfi Jones , Choi Junjeong , Kwon Doru , Koo JaSeung
Published: December 2021

The breast cancer microenvironment is unique since the breast tissue within which the tumour originates comprises predominantly adipocytes. Adipocytes secrete various growth factors and cytokines that are reported to influence tumour progression by induction of epithelial-mesenchymal transition (EMT) which enhances cancer cell migration, invasion, and metastasis. Immunohistochemical analysis reveals that the invading breast cancer invades surrounding adipose tissues resulting in the delipidation of adipose tissues. To determine the molecular mechanism underlying these events, we co-cultured human adipocytes and breast cancer cells. Co-cultured cells had increased CD36 expression, with fatty acid import. Genetic ablation of CD36 attenuates adipocyte-induced EMT and stemness. Molecular screening for pathways potentially involved in adipocyte-induced CD36 expression reveals activation of the STAT3 signaling axis. Our study identifies a feedforward loop between CD36 and STAT3; where STAT3 binds to the CD36 promoter, activating its expression and CD36 upregulates STAT3 signaling. Breast cancer cells co-cultured with adipocytes actively accumulate fatty acids and undergo metabolic reprogramming, with a shift towards fatty acid oxidation. Seahorse metabolic analysis reveals that co-cultured CD36-expressing cells assumed an energetic phenotype, indicating enhanced mitochondrial respiration. Thus, breast cancer cells alter their metabolic programs, with increased mitochondrial respiration, to meet their energy needs, with the availability of fatty acids. Analysis of breast cancer patient data reveals that increased CD36 expression occurs with increased FABP4 expression. Mechanistic experiments reveal that CD36 directly interacts with FABP4 to regulate fatty acid import, transport, and metabolism in co-cultured breast cancer cells. In vivo studies in mouse models reveal that combined chemical inhibition of CD36 and FABP4 resulted in a significant reduction in tumour growth rate. The study presents an alternative approach by which adipocytes may enhance cancer progression via the transfer of free fatty acids from tumour-associated adipocytes to breast cancer cells. The uptake of free fatty acid subsequently serves as a secondary source of energy to drive breast cancer cell progression. Targeting CD36 in combination with FABP4 may have a potential for therapies targeting the breast cancer microenvironment.

Citation Format: Jones Gyamfi, Junjeong Choi, Doru Kwon, JaSeung Koo. Interaction between CD36 and FABP4 regulates the import and metabolism of fatty acid in breast cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P263.
Genomic Landscape and Clinical Utility in Korean Advanced Pan-Cancer Patients from Prospective Clinical Sequencing: K-MASTER Program
Authors: Park Kyong Hwa , Choi Jung Yoon , Lim Ah-Reum , Kim Ju Won , Choi Yoon Ji , Lee Soohyeon , Sung Jae Sook , Chung Hee-Joon , Jang Byunghyun , Yoon Dayoung , Kim Sukwon , Sa Jason K. , Kim Yeul Hong
Published: December 2021

The fundamental principle of precision oncology is centralized on the identification of therapeutically exploitable targets that provides individual patients with cancer an opportunity to make informed decisions on a personalized level. To facilitate and adopt such concepts within clinical practice, we have initiated a nationwide, multi-institutional precision oncology screening program to examine and enroll patients into the most appropriate clinical trial based on their tumor's unique molecular properties. To determine the prevalence of essential major driver mutations and to explore their dynamic associations at both molecular and pathway levels, we present a comprehensive overview on the genomic properties of East Asian patients with cancer. We further delineate the extent of genomic diversity as well as clinical actionability in patients from Western and Eastern cultures at the pan-cancer and single-tumor entity levels. To support fellow oncology communities in future investigations involving large-scale analysis, all data have been made accessible to the public (https://kmportal.or.kr).

Significance:

We present a comprehensive overview of molecular properties of East Asian pan-cancer patients and demonstrate significant diversity in terms of genomic characteristics as well as clinical utility compared with patients with European ancestry. The results of this study will lay the groundwork for designing personalized treatments in the clinical setting.

See related commentary by Moyers and Subbiah, p. 886.

This article is highlighted in the In This Issue feature, p. 873