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Oehme, I.

Publications and source records attributed to Oehme, I..

8 recordsLinked to original sources

Sensitivity profiling reveals consistent drug responses across preclinical neuroblastoma models

Despite intensive treatment, overall survival for high-risk and relapse neuroblastoma patients remains below 50%. Even though comprehensive molecular profiling enables treatment stratification, druggable alterations have been identified for only a subset of patients. In vitro drug screening offers a complementary approach. Here, we compare the translational potential of three preclinical drug screening methods: ex vivo short-term, in vitro patient-derived organoid and in vivo patient-derived xenograft (PDX) drug testing. In total, 55 screens were performed from 38 neuroblastoma samples and five pediatric non-malignant samples, testing 77-224 drugs per screen. Ex vivo short-term drug screens achieved higher success rates than organoid screens (65% versus 23%) and shorter turnaround times (14 days versus 3-12 months). Matched samples showed consistent drug sensitivities across sample origin (patient versus PDX-derived; mean r = 0.84) and method (ex vivo short-term versus organoids; mean r = 0.87), demonstrating that ex vivo short-term screens recapitulate drug sensitivities found in long-term organoid models. In parallel, as part of the ITCC-P4 consortium, ten compounds were tested in vivo in eight PDX models, with samples matching the ex vivo screens. For seven out of ten clinically available compounds, ex vivo drug responses were comparable with in vivo responses in matched PDX models. These results demonstrate that, while organoids and PDX models remain essential for drug discovery, ex vivo short-term drug screening provides a rapid alternative for functional precision oncology in neuroblastoma.

cell biology↗

Systematic functional drug testing in patient-derived models reveals ex vivo sensitivities associated with clinical outcome in rare solid tumors

Rare cancers are individually uncommon but collectively represent a substantial share of cancer burden, with limited systemic treatment options for many entities. Molecular profiling identifies targetable alterations, but actionable findings are limited and responses can vary despite a matched target. This motivates complementary approaches that directly assess tumor drug response. Here, we establish a biopsy-compatible ex vivo drug sensitivity testing platform optimized for low input and reproducibility. Patient-derived material was tested either directly or following ex vivo expansion. Functional profiling was performed within clinically relevant timelines across models from 126 patients with rare advanced solid tumors. Drug responses were consistent between model types. In most samples, we identified at least one potentially active compound, supporting feasibility at biopsy-scale. High in vitro sensitivity was associated with clinical benefit and progression-free survival. These findings support functional drug sensitivity testing as a complementary component in precision oncology for adults with rare cancers. Statement of SignificanceThis study presents a biopsy-compatible drug sensitivity testing platform for phenotype-based therapy stratification in rare cancers. It identifies actionable ex vivo drug responses and shows associations with clinical outcome in patients treated with screened therapies. These findings support functional testing as a complementary additional layer of stratification for therapeutic prioritization.

cancer biology↗

Rapid proteasomal degradation of mutant feline McDonough sarcoma-like tyrosine kinase-3 overcomes tyrosine kinase inhibitor resistance of acute myeloid leukemia cells

BackgroundFeline McDonough sarcoma (FMS)-related receptor tyrosine kinase 3 with activating internal tandem duplications (FLT3-ITD) causes acute myeloid leukemia (AML). Targeted protein degraders for FLT3 have evolved as drugs against leukemia. MethodsWe synthesized and characterized MA191 as novel von Hippel-Lindau (VHL)-based proteolysis targeting chimera (PROTAC) for FLT3. We analyzed protein expression, protein degradation mechanisms, and posttranslational modifications by immunoblot. Selective proteasome modulation, an inactive stereoisomer of MA191, and siRNA confirmed the event-driven degradation of FLT3-ITD. Hematopoietic cell survival and differentiation were determined by flow cytometry using apoptosis and cell surface markers. As models, we used cultured and primary human AML cells, FLT3 inhibitor-resistant AML cells, mature blood cells, and hematopoietic stem cells. We scrutinized the databases DepMap, GEPIA2, Hemap, and HPA to assess FLT3 expression and patient survival. Experiments with Danio rerio larvae verified in vivo anti-leukemic activity of MA191. ANOVA and Bonferroni correction were used for statistics. ResultsMA191 is a rapid nanomolar apoptosis inducer in AML cells harboring FLT3-ITD (IC50=10.16-11.6 nM; EC50=0.015-0.883 {micro}M). A stereoisomer of MA191 that cannot recruit VHL demonstrates that elimination of FLT3-ITD is superior to its inhibition. MA191 abrogates FLT3 inhibitor resistance from rebound activation of mitogen-activated kinases. Rapid depletion of FLT3-ITD by MA191 (DC50=10 nM) requires VHL, neddylation, and the pro-apoptotic BH3-only protein BIM. Reduction of FLT3-ITD by MA191 precedes apoptosis. This reveals an apoptosis-independent function of BIM on protein stability. Leukemia cells express more FLT3 than healthy cells (n=3675/n=1249) and FLT3 expression is associated with worse AML patient survival (p=0.0099). MA191 does not harm blood cells and bone marrow progenitor cells and does not disturb myeloid blood cell differentiation. In Danio rerio, MA191 halts AML cell proliferation without significant toxicity. Anti-leukemic effects of MA191 are not susceptible to anti-apoptotic effects of human stromal cells and mutations in the tyrosine kinase of FLT3-ITD that confer resistance to selective FLT3 inhibitors. Conclusionsthese insights and the disclosure of the structure of MA191 provide a framework for an improved design of PROTACs that target mutant FLT3 and are not vulnerable to extrinsic and intrinsic resistance mechanisms. Degradation kinetics appear as determinant of such resistance breakers. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=188 SRC="FIGDIR/small/660791v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@17e5988org.highwire.dtl.DTLVardef@27fbc4org.highwire.dtl.DTLVardef@1023648org.highwire.dtl.DTLVardef@39bdcb_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

Phenotypic plasticity in a novel set of EGFR tyrosine kinase inhibitor-adapted non-small cell lung cancer cell lines

Here, we introduce sublines of the EGFR-mutant non-small cell lung cancer (NSCLC) cell lines HCC827 and HCC4006 adapted to the EGFR kinase inhibitors gefitinib (HCC827rGEFI2{micro}M, HCC4006rGEFI1{micro}M), erlotinib (HCC827rERLO2{micro}M, HCC4006rERLO1{micro}M), and afatinib (HCC827rAFA50nM, HCC4006rAFA100nM). All sublines displayed resistance to gefitinib, erlotinib, afatinib, and the third-generation EGFR kinase inhibitor osimertinib that overcomes T790M-mediated resistance. HCC4006rERLO1{micro}M displayed a spindle-like morphology in agreement with previous findings that had detected epithelial-mesenchymal-transition (EMT) in its precursor cell line HCC4006rERLO0.5{micro}M. EMT had also been reported for the HCC4006rGEFI1{micro}M precursor cell line HCC4006rGEFI0.5{micro}M and for HCC4006rAFA100nM, but the morphologies of HCC4006rGEFI1{micro}M or HCC4006rAFA100nM did not support this, suggesting plasticity in EMT regulation during the drug adaptation process and in established resistant cell lines. Accordingly, HCC4006rERLO1{micro}M displayed resistance to MEK and AKT inhibitors in contrast to its precursor HCC4006rERLO0.5{micro}M. We also detected metabolic plasticity, i.e., a temporary Warburg metabolism, in HCC4006 and HCC827rGEFI2{micro}M. Response profiles to cytotoxic anti-cancer drugs, kinase inhibitors, and HDAC inhibitors resulted in complex patterns that were specific for each individual subline without obvious overlaps, indicating individual resistance phenotypes. All resistant sublines remained sensitive or displayed collateral sensitivity to at least one of the investigated drugs. In conclusion, the comparison of EGFR kinase-resistant NSCLC sublines with their precursor cell lines that had been previously characterised at a lower resistance level and metabolic investigations indicated phenotypic plasticity during the resistance formation process and in established cell lines. This plasticity may contribute to the well-known variability in cell line phenotypes observed between different laboratories and in intra-laboratory experiments.

cancer biology↗

Glutaredoxin 3 (GLRX3) confers a fusion oncogene-dependent vulnerability to Ewing sarcoma

Ewing sarcoma (EwS) is a highly aggressive bone and soft-tissue associated cancer for which there are no effective targeted therapeutics available. Genetically, EwS is driven by aberrantly active EWSR1::ETS fusion transcription factors, most commonly EWSR1::FLI1. Despite their unique expression in EwS, all attempts to effectively target these fusion oncoproteins clinically were not yet successful, wherefore alternative targets are required. Here, we functionally characterize the evolutionarily conserved oxidative stress regulator glutaredoxin 3 (GLRX3) as a EwS-specific and EWSR1::FLI1-dependent vulnerability. Through integration of transcriptome-profiling, conditional drug screens in 3D cultures, and functional experiments, we discover that GLRX3 promotes EwS growth in vitro and in vivo, and that it has a key role in mitigation of oxidative stress and maintenance of iron homeostasis. These GLRX3 functions can be exploited in both GLRX3-high and -low expressing EwS cells by targeted therapeutics including CDK4/6 inhibitors and inducers of apoptotic and ferroptotic cell death. Collectively, our results exemplify how the interplay of an evolutionarily conserved oxidative stress regulator with a dominant oncogene can promote malignancy but provide opportunities for predictive diagnostics and personalized therapy.

cancer biology↗

Somatic gene delivery for flexible in vivo modeling of high-risk sarcoma

A particular challenge hampering therapeutic advancements for high-risk sarcoma patients is the broad spectrum of molecularly distinct sarcoma entities and the corresponding lack of suitable model systems to recapitulate and study these diseases. To overcome this predicament, we developed a novel genetically-controlled, yet versatile mouse modeling platform allowing delivery of different genetic lesions by electroporation (EPO) of the thigh muscle wildtype mice. This optimized sarcoma EPO-GEMM (EPO-based genetically engineered mouse model) platform allowed the generation of ten biologically distinct sarcoma entities, including Synovial Sarcoma (SS), fusion-positive and fusion-negative Rhabdomyosarcoma (RMS), Alveolar Soft Part Sarcoma (ASPS), Undifferentiated Pleomorphic Sarcoma (UPS) and Infantile Fibrosarcoma (IFS). Comprehensive molecular profiling and cross-species analyses confirmed faithful recapitulation of the human disease, including the expression of relevant immunotherapy targets. Syngeneic allografting enabled reliable preservation and scalability of Sarcoma-EPO-GEMMs for treatment trials, such as B7-H3-directed CAR-T cell therapy in an immunocompetent background.

cancer biology↗

Genomic and phenotypic stability of fusion-driven pediatric Ewing sarcoma cell lines

Human cancer cell lines are the mainstay of cancer research. Recent reports showed that highly mutated adult carcinoma cell lines (mainly HeLa and MCF-7) present striking diversity across laboratories and that long-term continuous culturing results in genomic/transcriptomic heterogeneity with strong phenotypical implications. This highlighted how despite human cell line models being powerful tools for cancer research, the findings derived from their use may present limitations in terms of reproducibility. However, to what extent these conclusions can be generalized to the majority of cancer cell lines remained unexplored. Here, we hypothesized that oligomutated pediatric sarcoma cell lines driven by a chimeric oncogenic transcription factor (COTF), such as Ewing sarcoma (EwS), were genetically and phenotypically more stable than the previously investigated (adult) carcinoma cell lines. A comprehensive molecular and phenotypic characterization of multiple EwS cell line strains in direct comparison to the HeLa and MCF-7 cell lines, together with a simultaneous analysis during 12 months of continuous cell culture showed that COTF-driven pediatric sarcoma cell line strains are genomically more stable than adult carcinoma strains, display remarkably stable and homogenous transcriptomes, and exhibit uniform and stable drug response. The analysis of multiple EwS cell lines subjected to long-term continuous culture conditions revealed that variable degrees of genomic/transcriptomic/phenotypic may be observed among COTF-driven cell lines, further exemplifying that the potential for reproducibility of in vitro scientific results may be rather understood as a spectrum, even within the same tumor entity.

cell biology↗

Chromosome 8 gain drives poor patient outcome via expression of 4E-BP1 in Ewing sarcoma

Chromosome 8 (chr8) gains are common in cancer. However, their potential contribution to tumor heterogeneity is largely unexplored. Ewing sarcoma (EwS) is characterized by pathognomonic FET::ETS fusions but a general paucity of other recurrent somatic mutations that could explain the observed clinical diversity. In EwS, chr8 gains are the second most common genetic alteration rendering EwS an ideal model to investigate the relevance of chr8 gains in an otherwise silent genomic context. Here, we report that chr8 gain-driven gene expression patterns correlate with poor overall survival of EwS patients. This effect is predominantly mediated by increased expression of the translation initiation factor binding protein 4E-BP1 encoded by EIF4EBP1 on chr8. High EIF4EBP1 expression showed the strongest association with poor patient survival among all chr8-encoded genes and correlated with chr8 gains in EwS tumors. Similar findings were made in numerous entities of The Cancer Genome Atlas (TCGA). Integrated multi-omics profiling uncovered that 4E-BP1 orchestrates a pro-proliferative proteomic network. Consistently, silencing of 4E-BP1 in the EwS model reduced cell proliferation, clonogenicity, spheroidal growth in vitro, and tumorigenesis in vivo. Drug screens and functional assays revealed that high 4E-BP1 expression sensitizes for pharmacological CDK4/6 inhibition in preclinical models. Collectively, we establish chr8 gains and high 4E-BP1 expression as prognostic biomarkers in EwS and demonstrate that their association with patient outcome is primarily mediated by 4E-BP1 orchestrating a pro-proliferative proteomic network sensitizing EwS for CDK4/6 inhibitors. Our data suggest that testing for chr8 gains may improve risk-stratification and therapeutic management in EwS and other cancers.

cancer biology↗