bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A060: Discovery of potent and selective EP300 degraders with anti-cancer activity
Authors: Zimmerman Mark , Sappal Darshan , Adam Ammar , Adams Benjamin , Adhikari Ketaki , Austin Wesley , Bullock Breanna , DiBernardo Julie , Dixon Thomas , Elliot GiNell , Ethell Brian , Gervais Anais , Hossain Md Imran , Huang David , Lahr Dave , Lin Mei Yun , Mayhew David , Mizeracka Karolina , Negretti Solymar , Nguyen Tyler , Prifti Olga , Schiller Shawn , Sherbanee Brenna , Terry David , Ucisik Nihan , Wittenborn Elizabeth , LaBonte Laura , Daniels Danette
Published: December 2023

E1A binding protein (EP300) and CREB binding protein (CBP) are paralog histone acetyltransferases involved in many cellular processes via their activity as transcriptional co-activators. Dysregulation of one or both proteins has been implicated in various cancers, and functional genomic screens have demonstrated a bidirectional synthetic lethal relationship between the two genes in tumor cells. Due to the high homology between EP300 and CBP, identifying chemical matter that selectively targets EP300 or CBP has proven challenging. Here, we describe a potent, highly selective heterobifunctional degrader of EP300 with biological activity in CBP-deficient and EP300-dependent tumor cells. This compound achieves robust degradation of EP300 in vivo at doses that sustain EP300 degradation with minimal effects on CBP protein level. Targeted degradation of EP300 protein resulted in a stronger suppression of cell growth and survival than targeting the bromodomain or HAT activity of EP300/CBP with small molecule inhibitors. Strong anti-proliferative effects have been demonstrated in multiple cancer types, including lymphomas and prostate tumors, highlighting the essential role of EP300 in the malignant phenotype of these tumors.

Citation Format: Mark Zimmerman, Darshan Sappal, Ammar Adam, Benjamin Adams, Ketaki Adhikari, Wesley Austin, Breanna Bullock, Julie DiBernardo, Thomas Dixon, GiNell Elliot, Brian Ethell, Anais Gervais, Md Imran Hossain, David Huang, Dave Lahr, Mei Yun Lin, David Mayhew, Karolina Mizeracka, Solymar Negretti, Tyler Nguyen, Olga Prifti, Shawn Schiller, Brenna Sherbanee, David Terry, Nihan Ucisik, Elizabeth Wittenborn, Laura LaBonte, Danette Daniels. Discovery of potent and selective EP300 degraders with anti-cancer activity [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A060.
Abstract A106: Pharmacological activation of CLIP3 reduces radioresistance by suppressing stemness and glycolysis in glioblastoma
Authors: Kang Hyunkoo , Shin Eunguk , Lee Haksoo , Youn BuHyun
Published: December 2023

Glioblastoma (GBM) is a malignant primary brain tumor in which the standard treatment, ionizing radiation (IR), achieves a median survival of less than 15 months. GBM harbors glioblastoma stem cells (GSCs), which are crucial in therapeutic resistance and recurrence. Here, we report that GSCs that survive standard treatment radiation upregulate Speedy/RINGO cell cycle regulator family member A (Spy1) and downregulate CAP-Gly domain-containing linker protein 3 (CLIP3). We discovered that Spy1 activation and CLIP3 inhibition coordinately shift GBM cell glucose metabolism to favor glycolysis via two cellular processes: transcriptional regulation of CLIP3 and facilitating Glucose transporter 3 (GLUT3) trafficking to cellular membranes in GBM cells. Importantly, in combination with IR, glimepiride, an FDA-approved medication used to treat type 2 diabetes mellitus, disrupts GSCs maintenance and suppresses glycolytic activity by restoring CLIP3 function. In addition, combining radiotherapy and glimepiride significantly reduced GBM growth and improved survival in a GBM orthotopic xenograft mouse model. Collectively, our data suggest that repurposing glimepiride for GBM therapy could be an attractive strategy for overcoming tumor recurrence. [This research was supported by National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2020M2D9A2094156) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2023-00207904).]

Citation Format: Hyunkoo Kang, Eunguk Shin, Haksoo Lee, BuHyun Youn. Pharmacological activation of CLIP3 reduces radioresistance by suppressing stemness and glycolysis in glioblastoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A106.
Abstract A107: Diacylglycerol kinase B mediates radioresistance by regulating mitochondrial lipotoxicity in glioblastoma
Authors: Lee Haksoo , Kang Hyunkoo , Shin Eunguk , Youn BuHyun
Published: December 2023

Glioblastoma (GBM) is a malignant primary brain tumor in which the standard treatment, ionizing radiation (IR), achieves a median survival of about 15 months. GBM cells that survive radiotherapy contribute to tumor progression and recurrence with metabolic rewiring. We established radioresistant GBM cells and identified that diacylglycerol kinase B (DGKB), a regulator of the intracellular concentration of diacylglycerol (DAG), is significantly downregulated in these cells. The downregulation of DGKB increases DAG accumulation and reduces fatty acid oxidation, conferring radioresistance by reducing mitochondrial ROS. Diacylglycerol acyltransferase 1 (DGAT1), which catalyzes the formation of triglycerides from DAG, is also increased in radioresistant GBM cells. Genetic inhibition of DGAT1 using miR-3918 mimic suppresses radioresistance. We discover that cladribine, an FDA-approved drug, activates DGKB and inhibits DGAT1 and sensitizes GBM cells to radiotherapy. Taken together, our study demonstrates that DGKB downregulation and DGAT1 upregulation contribute to radioresistance by reducing mitochondrial ROS and suggests DGKB and DGAT1 as therapeutic targets to overcome GBM radioresistance.  [This research was supported by National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2020M2D9A2094156) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2023-00207904).]

Citation Format: Haksoo Lee, Hyunkoo Kang, Eunguk Shin, BuHyun Youn. Diacylglycerol kinase B mediates radioresistance by regulating mitochondrial lipotoxicity in glioblastoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A107.
Abstract A120: Differentilal roles of PI3K catalytic kinases in glioblastoma's chemoresistance
Authors: Sheng Zhi
Published: December 2023

Resistance to chemotherapies such as temozolomide presents a major hurdle to effectively treat glioblastoma. This challenge arises possibly from the activation of phosphatidylinositol 3-kinase (PI3K) signaling, which makes PI3K an appealing therapeutic target. However, non-selectively blocking the four highly homologous PI3K catalytic kinases p110α, β, δ, and γ has yielded undesired clinical outcomes. It is therefore imperative to investigate individual PI3K kinases in glioblastoma’s chemosensitivity. Here we report that PI3K kinases differentially regulate chemosensitivity. We found that the four kinases were unequally expressed in grade II/III glioma and glioblastoma with levels of p110β being the highest. Concomitantly, glioblastoma patients deficient of O6-methylguanine-DNA-mehtyltransferase and expressing high levels of p110β and low levels of other kinases (p110β-high) were more likely resistant to temozolomide, thereby experiencing poor prognosis. Perturbation of p110β, but not other kinases, sensitized p110β-high glioblastoma cells or mouse xenograft tumors to temozolomide. Moreover, p110β-selective inhibitors and temozolomide synergistically mitigated the growth of resilient glioblastoma stem cells. Our results have demonstrated the essential role of p110β in regulating chemosensitivity, suggesting that selectively blocking p110β is an effective chemosensitizer for therapy-resistant glioblastoma.

Citation Format: Zhi Sheng. Differentilal roles of PI3K catalytic kinases in glioblastoma's chemoresistance [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A120.
Abstract A141: Preclinical pharmacokinetic (PK) and tumor growth inhibition (TGI) modeling for mANK-101, an anchored murine interleukin-12 (IL-12) complex for intratumoral administration for solid cancer
Authors: Mistry Hitesh , Hodson David , Orrell David , Battula Sailaja , Emens Leisha A , Kaufman Howard L , Schmidt Michael M , Chassagnole Christophe
Published: December 2023

Introduction – Murine ANK-101 (mANK-101) is a stable complex composed of a modified murine IL-12 cytokine with aluminum hydroxide at a 1:10 ratio designed for intratumoral delivery to established solid cancers. The objective of this work was to build a preclinical PK/PD/TGI model to gain a better mechanistic understanding of the pharmacology of mANK-101 and potential impact on therapeutic efficacy.

Methods - Data were collected from in vivo studies measuring PK, intratumoral immune cells and tumor growth inhibition (TGI) in a CT26 syngeneic mouse model treated with mANK-101. A PK model was derived from Momin et al. [1], the surrogacy potential of immune cells was assessed via a statistical model and subsequently a mathematical model linking immune cell activation to TGI was developed.

Results – A two-compartment PK model was established to take into account both the intratumoral depot effect of mANK-101 and the release into the peripheral circulation for mIL12 from the mANK-101 complex. CD8+ T-cell infiltration was found to be a surrogate biomarker for anti-tumor activity and was subsequently used to link PD-TGI. The model was able to capture various doses and schedules of mANK-101 at different starting tumor volumes on therapeutic responses.

Conclusions – A PK-PD-TGI model was developed that links the release of mIL12 from mANK-101 to immune cell-activation through to tumor growth inhibition thus providing a causal understanding of the mechanism of action. The model could potentially form the basis of a translational model to assist in designing first-in-man dose and schedule.

References:[1] Momin, N., Palmeri, J.R., Lutz, E.A. et al. Maximizing response to intratumoral immunotherapy in mice by tuning local retention. Nat Commun 13, 109 (2022). https://doi.org/10.1038/s41467-021-27390-6

Citation Format: Hitesh Mistry, David Hodson, David Orrell, Sailaja Battula, Leisha A Emens, Howard L Kaufman, Michael M Schmidt, Christophe Chassagnole. Preclinical pharmacokinetic (PK) and tumor growth inhibition (TGI) modeling for mANK-101, an anchored murine interleukin-12 (IL-12) complex for intratumoral administration for solid cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A141.
Abstract A144: HM99462, a Novel & potent SOS1 inhibitor, induces tumor regressions in combination with KRAS G12C inhibitor, MEK inhibitor, or EGFR mutant inhibitor
Authors: Choi Jaeyul , Jung Seung Hyun , Park Wongi , Byun Jooyun , Lim Semi , Lee Youngjoo , Jeon Soye , Kim Yu-Yon , Ahn Young Gil , Kim Young Hoon , Suh Kwee Hyun
Published: December 2023

Son of sevenless homolog 1 (SOS1) is one of guanine nucleotide exchange factor (GEF) responsible for a binary molecular switch to activate KRAS as well as a node in the negative feedback loop in the RTK-KRAS-MAPK signaling pathway. Therefore, combination strategies with a SOS1 inhibitor are being explored as a promising therapeutic options to target the MAPK-mediated bypass, which may improve antitumor activity or delay the induction of resistance after treatment. Herein, we presented a novel and potent SOS1 inhibitor, HM99462, which abrogates GTP-binding to KRAS and the profile of drug potency and mechanism of action was examined with in vitro and in vivo models. Biochemical activity on SOS1 was evaluated by a GTP-exchange assay on diverse KRAS G12X mutant types, NRAS Q61H, and HRAS G12V, and HM99462 showed excellent inhibitory activity, while SOS2 action was not affected. Moreover, HM99462 decreased ERK phosphorylation in various cancer cell lines harboring different major KRAS mutation statuses such as KRAS G12C, G12D, G12V, or G13D. Growth inhibition assay was performed using a three-dimensional (3D) conformation culture that mimics the complexity and heterogeneity of tumors and has elevated p-ERK. In this 3D spheroid growth inhibition assay, HM99462 demonstrated significantly effective GI50 against various KRAS mutant cancer cell lines. Additionally, HM99462 was evaluated in cancer cell xenograft mouse models harboring KRAS or EGFR mutation. The combination of HM99462 with KRAS G12C, MEK, or EGFR mutant inhibitor led to significantly synergistic anti-tumor activity in both in vitro and in vivo models with several KRAS or EGFR mutations. Based on our exploratory study, a novel and potent SOS1 inhibitor, HM99462 could be suggested as an appropriate therapeutic agent for diverse inhibitory activity against cancers causing by the hyperactivation of oncogenic KRAS or RTK signaling. And it has the potential to overcome the limitations of KRAS G12C, MEK or EGFR inhibitor through combination. IND enabling GLP-toxicity studies with HM99462 are currently underway, and we planned to initiate clinical study in early 2024.

Citation Format: Jaeyul Choi, Seung Hyun Jung, Wongi Park, Jooyun Byun, Semi Lim, Youngjoo Lee, Soye Jeon, Yu-Yon Kim, Young Gil Ahn, Young Hoon Kim, Kwee Hyun Suh. HM99462, a Novel & potent SOS1 inhibitor, induces tumor regressions in combination with KRAS G12C inhibitor, MEK inhibitor, or EGFR mutant inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A144.
Abstract B018: MTA-cooperative PRMT5 inhibitors selectively modulate RNA splicing in MTAP-deleted cancer cells across histologies
Authors: Tonini Matthew R , Meier Samuel R , Liu Shangtao , Cottrell Kevin M , Maxwell John P , Andersen Jannik N , Huang Alan , Cimmino Luisa , Briggs Kimberly J
Published: December 2023

PRMT5 is a type II arginine methyltransferase that forms an active complex with methylosome protein 50 (MEP50) to catalyze the symmetric dimethylation (SDMA) of arginine residues in proteins that regulate biological roles including modulation of apoptosis, DNA damage response and RNA processing.  Some of the best characterized PRMT5 substrates are SNRPB, SNRPD1 and SNRPD3, which are necessary for the formation of the spliceosome and therefore RNA splicing fidelity.  The development of MTA-cooperative PRMT5 inhibitors, including the clinical stage inhibitors TNG908 and TNG462, have been shown in preclinical studies to selectively inhibit PRMT5 in MTAP-deleted cancer cells while sparing normal, MTAP-intact cells.  Consistent with this selective, on-target mechanism, treatment with TNG908 in preclinical studies results in increased aberrant RNA splicing in MTAP-deleted cells relative to MTAP-intact cells.  As MTAP loss occurs in 10-15% of all human cancer, the identification of a signature of alternative splicing events may report pharmacodynamic activity of PRMT5 inhibitors and potentially predict patient response.  Similar splicing alterations caused by PRMT5 inhibition were identified in preclinical MTAP-deleted cancer models representing glioblastoma, non-small cell lung cancer, among others, suggesting the events are histology-agnostic.  Additionally, titration of exogenous MTA, an endogenous inhibitor of PRMT5, recapitulated the observed splicing events in preclinical MTAP-proficient cells.  Similar findings were observed utilizing a pharmacological inhibitor of MTAP suggesting that the identified alternative splicing events are dependent on accumulation of MTA.  Collectively, these data suggest that a PRMT5-dependent RNA splicing signature can be developed to identify solid tumors that may best respond to MTA-cooperative PRMT5 inhibitors as well as monitor their pharmacodynamic activity.

Citation Format: Matthew R Tonini, Samuel R Meier, Shangtao Liu, Kevin M Cottrell, John P Maxwell, Jannik N Andersen, Alan Huang, Luisa Cimmino, Kimberly J Briggs. MTA-cooperative PRMT5 inhibitors selectively modulate RNA splicing in MTAP-deleted cancer cells across histologies [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B018.
Abstract B029: Targeting phosphodiesterase: A potential strategy to treat LKB1-mutant cancers
Authors: Rono Catherine , Tang Xiaohu (Mark)
Published: December 2023

Cancer heterogeneity poses numerous challenges to treatment, underscoring the need for personalized/targeted therapies that align with each patient's specific genetic and molecular disease profile. Metabolic deregulation, often correlating with oncogenic alterations, is commonly observed in cancers. Such deregulation frequently presents metabolic vulnerabilities within the cancer, which could potentially be exploited for targeted therapy. Liver Kinase B1 (LKB1), a protein known for its diverse roles in cellular metabolism and its critical function as a tumor suppressor, ranks as the third most frequently mutated gene in non-small cell lung cancer (NSCLC). LKB1 mutations are linked to accelerated tumor progression and invasion, resulting in adverse clinical outcomes. Our research uncovers a novel role for LKB1 in cyclic nucleotide metabolism, wherein it suppresses a set of phosphodiesterase (PDE) expressions. Specifically, LKB1 represses PDE3 via the activation of the downstream salt-inducible kinase. Our data demonstrate that PDE3 modulators can selectively eliminate LKB1-deficient tumor cells while leaving LKB1-wildtype cells unharmed. However, some LKB1-deficient cells develop resistance due to the loss of SLFN12, whose expression is required for PDE3 modulator-induced cell death. Interestingly, this resistance can be overcome by inducing SLFN12 expression, through either epigenetic inhibitors or cAMP inducers. These findings not only broaden our understanding of the role of LKB1 in metabolic regulation but also suggest a promising strategy for targeted therapy against LKB1-mutant cancers.

Citation Format: Catherine Rono, Xiaohu (Mark) Tang. Targeting phosphodiesterase: A potential strategy to treat LKB1-mutant cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B029.
Abstract B061: Sensitivity and resistance mechanisms of human cancer cell lines treated with PARP, POLθ, and ATR inhibitor combinations in 2D and 3D spheroid cell viability assays
Authors: Melis Janneke J.T.M. , Kooijman Jeffrey , Wetemans Sabine , Geerdink-Datema Suzan , Dylus Jelle , de Roos Jeroen A.D.M. , van Riel Wilhelmina E. , Zaman Guido J.R.
Published: December 2023

Poly ADP Ribose Polymerase (PARP) inhibitors have changed the landscape of treatment of homologous recombination (HR) -deficient cancers. The combination of PARP targeting agents and genetic alterations in the HR pathway is known to be synthetically lethal. Currently, four PARP inhibitors are approved for treatment of HR-deficient cancers. In combination with DNA damaging agents, PARP inhibitors synergistically kill tumor cells. Occurrence of resistance to PARP inhibitors is a major problem in the clinic. Targeting alternative DNA repair pathways or the use of new drug combinations may overcome PARP inhibitor resistance. We have determined and compared the effect of inhibitors of PARP, POLθ and ATR on cell viability in a large panel of human cancer cell lines (the Oncolines® panel) in 2D cell viability assays, using intracellular ATP content as an indirect read-out of cell number. The relationship between the mutation and expression status of genes involved in the DNA damage response pathway, or known to be involved in PARP inhibitor resistance, was determined. The effect of co-treatment of PARP inhibitors with inhibitors of POLθ, ATR and DNA damaging, cytotoxic agents was determined in BLISS combination matrix experiments in the colorectal adenocarcinoma cell line DLD1 and an isogenic BRCA2-deficient knock-out derivative. Drug combinations were studied in 2D and in 3D spheroid viability assays. To identify novel, potential mechanisms of resistance to PARP inhibitors, BRCA1-deficient ovarian UWB1.289 and BRCA2-deficient DLD1 cells were treated with sequentially increasing concentrations of PARP inhibitors talazoparib or olaparib. Resistant clones were selected and characterized. Our study reveals insight into the genetic determinants of cancer cell line sensitivity to inhibitors of PARP, POLθ and ATR. We also present the first side-by-side comparative study of the effect of drug combinations targeting the DNA damage response pathway in HR-deficient tumors in 2D and 3D spheroid cell viability assays.

Citation Format: Janneke J.T.M. Melis, Jeffrey Kooijman, Sabine Wetemans, Suzan Geerdink-Datema, Jelle Dylus, Jeroen A.D.M. de Roos, Wilhelmina E. van Riel, Guido J.R. Zaman. Sensitivity and resistance mechanisms of human cancer cell lines treated with PARP, POLθ, and ATR inhibitor combinations in 2D and 3D spheroid cell viability assays [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B061.
Abstract B062: Loss of MED12 activates the TGFβ pathway to promote chemoresistance and replication fork stability in BRCA-deficient cells
Authors: Pale Lindsey M , Dhoonmoon Ashna , Hale Anastasia , Dennis Kady A , Schleicher Emily M , Nicolae Claudia M , Moldovan George-Lucian
Published: December 2023

Understanding chemoresistance mechanisms in BRCA-deficient cells will allow for identification of biomarkers for predicting tumor response to therapy, as well as the design of novel therapeutic approaches targeting this chemoresistance. Here, we show that the protein MED12, a component of the Mediator transcription regulation complex, plays an unexpected role in regulating chemosensitivity in BRCA-deficient cells. We found that loss of MED12 confers resistance to cisplatin and PARP inhibitors in both BRCA1- and BRCA2-deficient cells, which is associated with restoration of both homologous recombination and replication fork stability. Surprisingly, MED12-controlled chemosensitivity does not involve a function of the Mediator complex, but instead reflects a distinct role of MED12 in suppression of the TGFβ pathway. Importantly, we show that ectopic activation of the TGFβ pathway is enough to overcome the fork protection and DNA repair defects of BRCA-mutant cells, resulting in chemoresistance. Our work identifies the MED12-TGFβ module as an important regulator of genomic stability and chemosensitivity in BRCA-deficient cells.

Citation Format: Lindsey M Pale, Ashna Dhoonmoon, Anastasia Hale, Kady A Dennis, Emily M Schleicher, Claudia M Nicolae, George-Lucian Moldovan. Loss of MED12 activates the TGFβ pathway to promote chemoresistance and replication fork stability in BRCA-deficient cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B062.
Abstract B068: Modulation of the DNA damage response by novel Ku-DNA binding inhibitors enhances cellular effects of DNA-double strand break inducing agents
Authors: Mendoza-Munoz Pamela L , Chauhan Dineshsinha , Gavande Navnath S , Turchi John J
Published: December 2023

The DNA-dependent protein kinase (DNA-PK) plays a critical role in the non-homologous end joining (NHEJ) double-strand break (DSB) repair pathway and the DNA damage response (DDR). Consequently, blocking DNA-PK kinase activity is being pursued as a therapeutic strategy for the treatment of cancer in combination with DNA-double strand break inducing agents. We have previously reported the development of Ku-DNA binding inhibitors (Ku-DBi’s) that act via a novel mechanism of action to inhibit DNA-PK catalytic kinase activity by targeting the Ku 70/80 heterodimer interaction with DNA. Ku-DBi’s display nanomolar activity in vitro, possess cellular DNA-PK and NHEJ inhibitory activity, and sensitize non-small cell lung cancer (NSCLC) cells to DSB generating therapies bleomycin, etoposide and ionizing radiation. In this study, we have expanded our structure activity relationship analyses to focus on optimizing cellular uptake and reducing protein binding. We present the synthesis and analysis of a new series of Ku-DBi’s which demonstrated that chemical modifications of the X80 core structure can be implemented to achieve these goals while retaining Ku inhibitory activity. Furthermore, novel relationships with in vitro inhibitory activity were identified as a function of new pharmacophore additions. In addition, these novel compounds display reduced non-specific protein binding, increased cellular uptake, and enhanced cellular inhibition on DNA-double strand break repair. These novel compounds enable cellular studies to be conducted in serum contain media and the pursuit of in vivo analysis and represent a significant advance in the development of Ku-DNA binding inhibitors.

Citation Format: Pamela L Mendoza-Munoz, Dineshsinha Chauhan, Navnath S Gavande, John J Turchi. Modulation of the DNA damage response by novel Ku-DNA binding inhibitors enhances cellular effects of DNA-double strand break inducing agents [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B068.
Abstract B080: Non-genetic determinants driving sub-clonal resistance to KRAS G12C combination therapies in KRAS mutant non-small cell lung cancer
Authors: Li Chendi , Graser Christopher J , Qin Qian , Syed Usman M , Karakyriakou Barbara , Clark Sarah E , Saiki Anne Y , Hughes Paul E , Ott Christopher , Pinello Luca , Michor Franziska , Hata Aaron N
Published: December 2023

The FDA approval of the KRAS G12C inhibitor (G12Ci) sotorasib and the advancement of similar drugs into the clinic marks a major milestone in treating KRAS G12C non-small cell lung cancer (NSCLC). However, not all patients respond (sotorasib – ORR = 37.1%, adagrasib - 43%, JDQ443 – 35%), motivating preclinical and clinical investigation into mechanisms of intrinsic and acquired resistance. For instance, clinical studies have reported on-target KRAS mutations and preclinical studies have demonstrated mitogen-activated protein kinase (MAPK) feedback reactivation including EGFR, SHP2, and WT RAS signaling. In response to targeted therapies, sub-populations of cells can enter quiescence or specific epigenetic-driven states that confer drug tolerance. However, epigenetic states defining drug-tolerant persister populations and contributing to adaptive resistance to KRAS G12Ci have not been reported. Using a high-complexity DNA-barcoding system and mathematical modeling, we observed that pre-existing resistant clones to KRAS G12Ci gain clonal fitness during treatment independent of growth rate. Using single-cell profiling and RNA-lineage tracing barcoded systems, we identified distinct subpopulations of cells defined by specific chromatin and transcriptional states, including activation of interferon-gamma genes (ISG) and increased chromatin accessibility for pioneer transcription factors, which may contribute to MAPK reactivation-driven resistance. These results suggest a potential role of pioneer transcription factor-activated interferon-gamma response in driving MAPK feedback reactivation in KRAS G12Ci- resistant tumor subpopulations.

Citation Format: Chendi Li, Christopher J Graser, Qian Qin, Usman M Syed, Barbara Karakyriakou, Sarah E Clark, Anne Y Saiki, Paul E Hughes, Christopher Ott, Luca Pinello, Franziska Michor, Aaron N Hata. Non-genetic determinants driving sub-clonal resistance to KRAS G12C combination therapies in KRAS mutant non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B080.
Abstract B105: Antineoplastic effects and expression modulations in proliferation/apoptosis related genes by riproximin in breast cancer cells
Authors: Pervaiz Asim , Khan Asma , Umer Kiran , Berger Martin R.
Published: December 2023

Background: Ribosomal inactivating proteins (RIPs) target the ribosomal machinery of target cells and stop the translational machinery irreversibly. Riproximin is a plant-based RIP which was extracted and purified from the plant “Ximenia americana”. Riproximin has demonstrated its anticancer effects against various in vitro and in vivo cancer models. In this study, the focus was to evaluate the effects of riproximin on proliferation and apoptosis of breast cancer cells at functional and molecular levels.

Methods: MTT dye reduction assay and DAPI nuclear staining methodologies were used to highlight the riproximin mediated effects on proliferation and apoptosis in primary (MCF-7) and metastatic (MDA-MB-231) breast cancer cell lines. Afterwards, the two cell lines were used to investigate the expression modulations in genes related to PIK3/Akt and apoptosis pathways (84 genes/pathway) via real-time PCR methodology. The expression modulations were used to build the signalling pathways via Ingenuity Pathway Analysis supported by Qiagen software system.

Results: Riproximin successfully halted the proliferation of the breast cancer cells with an average 50% inhibitory concentrations of 1.2 and 2.9 ng/ml after 72 hours exposure interval in MCF-7 and MDA-MB-231 cells, respectively. The protein also induced apoptotic effects in the two cell lines as reflected by shrinkage, blebbing and fragmentation of the nucleus/DNA content in a concentration dependant format. Substantial alterations (≥2fold) were observed in PIK3/Akt pathway genes (MCF-7: 49/84, MDA-MB-231: 28/84) in response to riproximin exposure. Similarly, the protein induced de-regulation (≥2fold) of apoptosis related 44/84 and 34/84 genes in MCF-7 and MDA-MB-231 cell lines, respectively. The Ingenuity Pathway Analysis revealed involvement of these genes at distinct positions in cell survival and death mechanisms.

Conclusion: Riproximin demonstrated the substantial potential to induce the cytotoxic effects in breast cancer cells. The protein also de-regulated a significant number of proliferation and apoptosis related genes in breast cancer primary and metastatic cells. Further in vitro investigations are required to understand the fine molecular tuning being operated by this natural plant protein in cancer cells. 

Citation Format: Asim Pervaiz, Asma Khan, Kiran Umer, Martin R. Berger. Antineoplastic effects and expression modulations in proliferation/apoptosis related genes by riproximin in breast cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B105.
Abstract C010: A comprehensive predictive biomarker analysis for MEK Inhibitors in Patient-derived Xenograft (PDX) models
Authors: Sheng Yanghui , Qian Wubin , Wang Jingjing , Guo Sheng
Published: December 2023

Introduction: The RAS-RAF-MEK-ERK pathway has been extensively studied for its prominent role in cancer development. Activating mutations in receptor tyrosine kinases, RAS, or RAF, are commonly observed in cancer. Pathway activation caused by these mutations is mediated through MEK kinases, making MEK inhibition an attractive therapeutic strategy. Although several in vitro studies have been carried out to identify predictive biomarkers for sensitivity to MEK inhibition, the results have not been validated in vivo.

Methods: Cryopreserved or fresh PDX tumor tissues (~2–3 mm in diameter) were transplanted into NOD/SCID or BALB/c nude mice subcutaneously. Trametinib was administered orally daily at 0.3mg - 1mg/kg of body weight, starting when tumor size reached 100-300 mm3. Sequencing reads were aligned to both human and mouse reference genomes. Based on which alignment yielded fewer mismatches, they were subsequently sorted into human or mouse groups, representing cancer and stromal transcriptomes, respectively. Ambiguous readings were discarded. Transcript abundance was quantified using the Kallisto software tool. Nucleotide variants in human genes were detected using the GATK best practice workflow.

Results: We systematically analyzed tumor growth data collected from 62 PDX models in 9 cancer types (colorectal, head and neck, esophageal, kidney, melanoma, lung, gastric, ovarian, and pancreatic) treated with Trametinib, an allosteric MEK1/2 inhibitor. The responses to Trametinib were classified into 3 categories based on the amount of tumor growth inhibition (TGI) achieved. About 20% of these models were sensitive to Trametinib treatment (TGI > 70% compared to vehicle), 35% were resistant (TGI ≤ 30% compared to vehicle), and the remaining showed a partial response (30% < TGI ≤ 70% compared to vehicle). Cross-group comparisons of PDX transcriptomic and mutation profiles allowed identification of novel biomarkers as well as validation of biomarkers previously reported in in vitro studies.

Conclusions: The different sensitivity to MEK inhibition observed in PDX models mirrors the patient heterogeneity observed in clinic. Thus, our results highlight the need to identify the appropriate genetic background using predictive biomarkers when applying targeted therapies.

Citation Format: Yanghui Sheng, Wubin Qian, Jingjing Wang, Sheng Guo. A comprehensive predictive biomarker analysis for MEK Inhibitors in Patient-derived Xenograft (PDX) models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C010.
Abstract C042: Integrative analyses of CRISPR and drug screens identify a selective and potent compound for oral squamous cell carcinoma
Authors: Chai Annie Wai Yeeng , Tan Yee Hua , Ooi Shiyin , Yee Pei San , Yee Shi Mun , Lightfoot Howard , Bathorpe Syd , Garnett Mathew J , Cheong Sok Ching
Published: December 2023

Mechanism-guided drug repurposing can accelerate the development of therapeutic strategies for oral squamous cell carcinoma (OSCC), which has an unmet clinical need. We integrated cell line sensitivity data for 339 anti-cancer drugs with genome-wide CRISPR-Cas9 screen gene essentiality data for 21 unique OSCC cell lines, derived primarily from Asian patients. We identified a significant correlation between AZD5582 sensitivity (an antagonist of the inhibitor of apoptosis (IAP) family proteins), and dependency on several members of the NF kappa-B pathway (RNF31, MAP3K7 and IKBKG). Dependent OSCC lines are more sensitive to AZD5582, with nanomolar range half-maximal inhibitory drug concentrations (IC50). We confirmed the on-target specificity and potency of AZD5582 in vitro and in vivo. Furthermore, AZD5582 sensitivity was associated with high levels of tumor necrosis factor (TNF) and either functional apoptotic or necroptotic pathways. In summary, our approach of integrating pharmacological and CRISPR screen data in a unique cohort of OSCC cell lines data has enabled the identification of specific dependencies and drug repurposing candidates.

Citation Format: Annie Wai Yeeng Chai, Yee Hua Tan, Shiyin Ooi, Pei San Yee, Shi Mun Yee, Howard Lightfoot, Syd Bathorpe, Mathew J Garnett, Sok Ching Cheong. Integrative analyses of CRISPR and drug screens identify a selective and potent compound for oral squamous cell carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C042.
Abstract C066: Update on the phase 1 trial of Nelmastobart in patients with advanced solid tumors
Authors: Yoo Stephen , Lee Soohyeon , Shin Sangjoon , LoRusso Particia , Hur Jiwon , Jung Hyunjin , Hong David S
Published: December 2023

Background: Butyrophilin 1A1 (BTN1A1) is a novel immune checkpoint that is found to be mutually exclusive with PD-(L)1. BTN1A1 has the potential to broaden the range of immunotherapeutic treatments available for patients who are currently unresponsive to anti-PD-(L)1 therapy. In this phase, 1 clinical trial, the safety and preliminary efficacy of Nelmastobart (hSTC81), a humanized monoclonal antibody targeting BTN1A1, was evaluated in patients with advanced solid tumors.

Methods: This is a first-in-human, phase 1, dose-escalation study evaluating Nelmastobart in pts with advanced solid tumors. Primary objectives are to characterize the safety profile and determine the maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D). Nelmastobart is administered as monotherapy at increasing dose levels of 0.3, 1, 3, 6, 10, and 15 mg/kg on a Q2W schedule.

Results: As of June 30, 2023, 45 pts are enrolled at dose levels of 0.3 (n=1), 1 (n=9), 3 (n=10), 6 (n=9), 10 (n=9), and 15 mg/kg (n=8). Of note, 3 pts with ovarian cancer at dose levels of 6 (n=1), 10 (n=1), 15 mg/kg (n=1), and 1 pt with thymic cancer at the dose level of 6 mg/kg (n=1) were enrolled. A maximum administered dose of 15 mg/kg was achieved; no DLTs were observed at any dose level. Focusing on the ovarian/thymic cancer subgroup, 2 pts are ongoing: 1 pt with ovarian cancer (10 mg/kg) and 1 pt with thymic cancer (6 mg/kg). The median duration of therapy was 20 weeks (maximum 33 weeks). Only 1 pt with ovarian cancer (6 mg/kg) reported any treatment-related adverse events (TRAE), including grade 1 headache, nausea, myalgia, and decreased appetite. In the evaluable pts, two confirmed stable diseases are observed in thymic cancer (6 mg/kg) and ovarian cancer (10 mg/kg). The median duration of SD pts is 29 weeks. Preliminary pharmacokinetic (PK) analysis revealed consistent exposure with linear PK. Pharmacodynamic analysis measuring cytokines and cell-based markers is pending and will be shared.

Conclusion: Nelmastobart demonstrates excellent tolerability without any DLTs up to the highest administered dose of 15 mg/kg. The available data show promising signs of anti-tumor activity, along with sustained stable disease. Currently, clinical development planning for a phase Ib/II clinical trial is underway, aiming to investigate the optimal therapeutic dose and efficacy of Nelmastobart in multiple types of solid tumors.

Citation Format: Stephen Yoo, Soohyeon Lee, Sangjoon Shin, Particia LoRusso, Jiwon Hur, Hyunjin Jung, David S Hong. Update on the phase 1 trial of Nelmastobart in patients with advanced solid tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C066.
Abstract C069: Toripalimab an anti-PD-1 antibody that demonstrates potent T cell activation and enhanced clinical efficacy irrespective of PD-L1 status
Authors: Wang Xiaoguang , Ravindranathan Sruthi , Chin Daniel , Tseng Su-Yi , Klakamp Scott , Widmann Kate , Kapoor Varun , Vexler Vladimir , Keegan Patricia , Yao Sheng , Khare Sanjay D , LaVallee Theresa , Rajasekaran Narendiran
Published: December 2023

Immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) have revolutionized cancer treatment favoring prognostic benefits to a broad range of cancer patients. Currently, US Food and Drug Administration (FDA)–approved PD-1 monoclonal antibodies (mAbs) have demonstrated significant clinical benefit, particularly in patients with programmed cell death ligand 1 (PD-L1)-expressing tumors. Toripalimab is a PD-1 targeting humanized IgG4 mAb that is currently pending approval by the FDA as a first-line treatment for patients with recurrent or metastatic nasopharyngeal carcinoma (RM-NPC). In combination with chemotherapy, toripalimab demonstrated significant clinical efficacy irrespective of PD-L1 status in patients in three different clinical trials, namely JUPITER-02 (NPC), JUPITER-06 (esophageal squamous cell carcinoma [ESCC]) and CHOICE-01 (non-small cell lung cancer [NSCLC]). Here we investigated the molecular and functional characteristics of toripalimab and compared it to pembrolizumab, a PD-1 mAb that is approved in the largest number of indications in the PD-1 mAb class. In comparison to pembrolizumab, toripalimab demonstrated a 12-fold higher binding affinity to PD-1 and selectively induced higher Th1 and myeloid derived inflammatory cytokine responses in human peripheral blood mononuclear cells (PBMCs). Upon treating dissociated tumor cells from treatment naïve NSCLC patients, toripalimab demonstrated an enhanced expression of several unique genes in interferon gamma and immune cell pathways compared to pembrolizumab. The binding of toripalimab to PD-1 ectopically expressed in Jurkat T cells, recruited lower levels of SHP1 and SHP2, the negative regulators of T cell activation, compared to pembrolizumab. Overall, our study demonstrates that toripalimab is differentiated from pembrolizumab in terms of stronger PD-1 binding, more potent in-vitro T cell activation and lower agonistic potential. These characteristics of toripalimab present it as a next generation PD-1 checkpoint inhibitor with potential for favorable clinical outcomes in treating cancer patients irrespective of their PD-L1 status.

Citation Format: Xiaoguang Wang, Sruthi Ravindranathan, Daniel Chin, Su-Yi Tseng, Scott Klakamp, Kate Widmann, Varun Kapoor, Vladimir Vexler, Patricia Keegan, Sheng Yao, Sanjay D Khare, Theresa LaVallee, Narendiran Rajasekaran. Toripalimab an anti-PD-1 antibody that demonstrates potent T cell activation and enhanced clinical efficacy irrespective of PD-L1 status [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C069.
Abstract C084: Metabolomic profiling identifies molecular modifiers contributing to proteasome inhibitor resistance in multiple myeloma
Authors: Gaikwad Snehal M , Hughitt Vincent Keith , Gyabaah-Kessie Nana , Matera-Vatnick Mikaela , Michalowski Aleksandra A , Quintanilla-Arteaga Anaisa , Andresson Thorkell , Mock Beverly A
Published: December 2023

Metabolic reprogramming plays a crucial role in the maintenance and differentiation of various cancers, including multiple myeloma (MM), the second-most common incurable hematological malignancy. Drug resistance poses a significant challenge to conventional proteasome inhibitor (PI) based therapy. A body of literature suggests that several metabolites are significantly deregulated in MM patients, however, their role in driving resistance is unclear. This study aims to identify metabolites modulated during acquired resistance to proteasome inhibitors in relapsed refractory (RR)MM. Two clinically relevant cell line models of PI-resistance (PIR) were developed by dose-escalation of the PI over one year. Cell cytotoxicity assays, immunoblotting, immunofluorescence, and flow cytometric analyses were used to assess the resistance phenotype. Mass spectrometry-based metabolomic profiling was performed to identify altered metabolites in resistant as compared to sensitive cell lines.  PIR cells demonstrated pan-resistance to multiple PIs, including a >10-fold increase in IC50 for oprozomib compared to parental cells. PIR cells had higher bioenergetic and glycolytic activity (Seahorse) while gene expression profiling suggested downregulation of oxidative phosphorylation. Mass spectrometry-based metabolomic profiling identified distinct metabolites deregulated in drug-resistant cells. The metabolomic profiles of the drug-resistant cell lines showed that the lipid synthesis and beta-oxidation of fatty acid pathways were highly modulated. Several pathway components demonstrated a negative association with overall survival in multiple myeloma patient datasets (MMRF, GSE31161 & GSE9782). PI resistance led to increased phosphorylation of ACLY involved in fatty acid synthesis and increased expression of CPT1A indicative of activation of the beta-oxidation pathway. Use of ACLY and FASN tool compounds affected proliferation, survival, and response to treatment in PIR cells. Metabolites modulated during acquired resistance to proteasome inhibitor in relapsed refractory (RR)MM were identified and potential mechanisms driving resistance were studied.

Citation Format: Snehal M Gaikwad, Vincent Keith Hughitt, Nana Gyabaah-Kessie, Mikaela Matera-Vatnick, Aleksandra A Michalowski, Anaisa Quintanilla-Arteaga, Thorkell Andresson, Beverly A Mock. Metabolomic profiling identifies molecular modifiers contributing to proteasome inhibitor resistance in multiple myeloma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C084.
Abstract C089: PRMT5 as a novel druggable vulnerability for EWSR1-ATF1-driven clear cell sarcoma
Authors: Li Bingbing X , David Larry L , Davis Lara E , Xiao Xiangshu
Published: December 2023

Clear cell sarcoma of soft tissue (CCSST) is a rare and aggressive soft tissue sarcoma. The 5-year survival rate is only 20% for metastatic cases of CCSST. CCSST is insensitive to existing chemotherapies or radiotherapy. New target therapies will have tremendous impact on CCSST patients. The hallmark of CCSST is a chromosome translocation, which generates an oncogene EWSR1-ATF1, where Ewing’s sarcoma gene (EWSR1) is fused with activating transcription factor 1 (ATF1). EWSR1-ATF1 is a constitutively active form of ATF1 and is independent of extracellular cues to drive ATF1-dependent gene transcription. We recently discovered that protein arginine methyltransferase 5 (PRMT5) is involved in EWSR1-ATF1-mediated gene transcription. Genetic silencing of PRMT5 in CCSST cells results in severely inhibited cell growth. We further identified a PRMT5 inhibitor JNJ-64619178 to potently and efficaciously inhibit CCSST cell growth in vitro and in vivo. This becomes clinically very relevant as JNJ-64619178 finished phase I clinical trial (NCT03573310) in advanced solid tumors and non-Hodgkin lymphoma patients and it demonstrated manageable toxicity. Our results presented here provide a strong mechanistic basis for further clinical evaluation of JNJ-64619178 to treat CCSST patients.

Citation Format: Bingbing X Li, Larry L David, Lara E Davis, Xiangshu Xiao. PRMT5 as a novel druggable vulnerability for EWSR1-ATF1-driven clear cell sarcoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C089.