High-grade brain tumours are characterized by inter- and intratumour heterogeneity and remain incurable despite current multi-modality treatment. The cellular aggressiveness within brain tumours includes tumour cell invasion of healthy brain tissue, resistance to conventional therapy, and greatly enhanced growth potential. This has been attributed to undifferentiated/stem cell-like features and clonal expansion under therapeutic pressure. The evolving notion of cancer cell plasticity implies that tumour cells may alter their phenotype both randomly and in response to external cues. In this context, we aim to elucidate the molecular mechanisms regulating glioma cell fate. We investigate selective small molecule-induced phenotypic changes such as ‘forced’ differentiation, surface-molecule expression, neurite outgrowth, autophagy, and apoptosis using patient-derived glioma models. Notably, these models display variability in cellular stemness/differentiation characteristics as well as glioma subtype-related classifiers. We therefore further analyse these small molecule-induced phenotypes at the single cell level using gene expression analysis. In addition to chemical/genetic-inspired approaches in vitro, we evaluate the tumour growth and invasion potential of glioma cell phenotypes in vivo. Together, these approaches have revealed molecular vulnerabilities (for example the TACC3-ARNT and HIF axis) that are required for aggressive glioma cell behaviour and may be pharmacologically exploitable for combination therapy.
Abstract Mucin 1 (MUC1) and epidermal growth factor receptor (EGFR) are co-expressed at high prevalence in multiple cancer indications such as non-small cell lung cancer (NSCLC), esophageal squamous cell carcinoma (ESCC), head and neck squamous cell carcinoma, triple negative breast cancer and ovarian cancer. Tumor-associated MUC1 is hypoglycosylated and exposes peptide epitopes within its extracellular domain, which are not accessible to antibodies in normal epithelial tissue. MUC1 co-localizes with EGFR as a result of loss of cell polarity in tumor cells. M1231 is a bispecific antibody-drug conjugate (ADC) based on a SEED (strand-exchange engineered domain)-antibody scaffold targeting tumor-associated MUC1 and EGFR. Sutro Biopharma’s cell free expression system Xpress CF+™ enables incorporation of non-natural amino acids at precise positions in the SEED-antibody for site-specific linker-payload conjugation. The cytotoxic payload of M1231 (SC209) is a hemiasterlin-related microtubule inhibitor. The cleavable linker (ValCit-PABA) maintained ADC stability in human plasma in vitro, ensuring low systemic payload release. Pre-clinical activity of M1231 was assessed in vitro in cancer cell lines and in vivo in NSCLC and ESCC patient-derived xenograft (PDX) models. M1231 inhibited tumor cell viability in vitro at sub-nanomolar IC50 values. The bispecific MUC1xEGFR antibody has demonstrated superior internalization and lysosomal trafficking compared to monospecific bivalent antibodies. Efficient ADC uptake resulted in superior antitumor activity of M1231 in PDX models compared to monospecific bivalent ADCs. M1231 demonstrated durable and dose-dependent antitumor activity in PDX models. Strong antitumor activity with complete regression was observed in NSCLC and ESCC PDX models following a single treatment of M1231. M1231 antitumor activity was associated with high target expression in NSCLC PDX models and was observed across a range of target expression levels in ESCC models. In summary, efficient payload delivery to tumor cells and strong antitumor activity of M1231 indicate that M1231 may have the potential to deliver an efficacy benefit to patients with tumors co-expressing MUC1 and EGFR. Citation Format: Christine Knuehl, Lars Toleikis, Julia Dotterweich, Jianguo Ma, Seema Kumar, Edith Ross, Claudia Wilm, Martina Schmitt, Hans Juergen Grote, Christiane Amendt. M1231 is a bispecific anti-MUC1xEGFR antibody-drug conjugate designed to treat solid tumors with MUC1 and EGFR co-expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5284.
TL-895 (formerly known as M7583) is a potent, highly selective, adenosine triphosphate (ATP)-competitive, second-generation, irreversible inhibitor of Bruton's tyrosine kinase (BTK). We characterized its biochemical and cellular effects in in vitro and in vivo models. TL-895 was evaluated preclinically for potency against BTK using IC50 concentration-response curves; selectivity using a 270-kinase panel; BTK phosphorylation in Ramos Burkitt's lymphoma cells by ProteinSimple Wes analysis of one study; anti-proliferative effects in primary chronic lymphocytic leukemia (CLL) blasts; cell viability effects in diffuse large B-cell lymphoma (DLBCL) and mantle-cell lymphoma (MCL) cell lines; effects on antibody-dependent cell-mediated cytotoxicity (ADCC) from Daudi cells and chromium-51 release from human tumor cell lines; and efficacy in vivo using four MCL xenograft model and 21 DLBCL patient-derived xenograft (PDX) models (subtypes: 9 ABC, 11 GCB, 1 Unclassified). TL-895 was active against recombinant BTK (average IC50 1.5 nM) and inhibited only three additional kinases with IC50 within tenfold of BTK activity. TL-895 inhibited BTK auto-phosphorylation at the Y223 phosphorylation site (IC50 1-10 nM). TL-895 inhibited the proliferation of primary CLL blasts in vitro and inhibited growth in a subset of activated DLBCL and MCL cell lines. TL-895 inhibited the ADCC mechanism of therapeutic antibodies only at supra-clinical exposure levels. TL-895 significantly inhibited tumor growth in the Mino MCL xenograft model and in 5/21 DLBCL PDX models relative to vehicle controls. These findings demonstrate the potency of TL-895 for BTK and its efficacy in models of B-cell lymphoma despite its refined selectivity.
Chromosomal aberration and DNA copy number change are robust hallmarks of cancer. The gold standard for detecting copy number changes in tumor cells is fluorescence in situ hybridization (FISH) using locus-specific probes that are imaged as fluorescent spots. However, spot counting often does not perform well on solid tumor tissue sections due to partially represented or overlapping nuclei.
Abstract Malignant pleural mesothelioma is an aggressive, asbestos-related cancer most commonly arising from the mesothelial cells lining the pleural cavity surrounding the lung. Despite the poor prognosis and increasing incidence of this disease, the combination of pemetrexed with cisplatin currently remains the only available treatment option to patients. Molecular characterization of mesothelioma tumors indicates a potential dependency on autocrine FGF-FGFR signaling. Based on this information, the therapeutic activity of M6123, a potent and selective, monovalent antagonist of FGFR1, was investigated in preclinical mesothelioma models in vitro and in vivo. In a panel of mesothelioma cell lines, M6123 mediated cellular growth reduction was clearly correlated with the level of endogenous FGF2 ligand. M6123 monotherapy significantly inhibited FGFR1 signal transduction and tumor growth in a cell line derived mesothelioma model. Furthermore, combination benefit was observed for M6123 with standard of care (SoC) chemotherapy. In a panel of nine mesothelioma patient derived xenograft (PDX) models, 66% (6/9) were sensitive to the combination of M6123 plus pemetrexed/cisplatin compared to 33% (3/9) for chemotherapy alone. The expression of a focused set of FGF-FGFR pathway genes was examined in PDX models to elucidate potential predictive biomarkers of sensitivity to M6123. Sprouty homolog 2 (SPRY2), a negative regulator of FGFR1 signaling, was upregulated in non-sensitive PDX models, whilst positive regulators of FGFR1 signaling including the ligand FGF5, the coreceptor FGFRL1 (FGFR5) and the downstream transcription factor ELK3 were elevated in sensitive models. In summary, M6123 showed favorable anti-tumor activity in preclinical models of mesothelioma, in particular in combination with standard of care chemotherapy. Further preclinical testing is warranted to confirm a predictive biomarker signature for selection of mesothelioma patients that may benefit from addition of M6123. Citation Format: Christina Esdar, Edith Ross, Michael Sanderson, Astrid Zimmermann. M6123, a selective FGFR1 antagonist, demonstrates anti-tumor activity as monotherapy and in combination with chemotherapy in mesothelioma models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 558.
Abstract Copy number alterations constitute important phenomena in tumor evolution. Whole genome single-cell sequencing gives insight into copy number profiles of individual cells, but is highly noisy. Here, we propose CONET, a probabilistic model for joint inference of the evolutionary tree on copy number events and copy number calling. CONET employs an efficient, regularized MCMC procedure to search the space of possible model structures and parameters. We introduce a range of model priors and penalties for efficient regularization. CONET reveals copy number evolution in two breast cancer samples, and outperforms other methods in tree reconstruction, breakpoint identification and copy number calling.
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