Biology subjects
Publications and source records attributed to Moustafa, M..
This study showcases the feasibility of oxygen ion ultra-high dose rate irradiation for in vitro and in vivo experiments at the Heidelberg Ion-Beam Therapy Center. The results indicate comparable effectiveness to standard dose rate in pancreatic cancer cell killing and tumor control, highlighting its potential to address challenges in treating radio-resistant tumors.
Managing aggressive meningiomas remains challenging due to limited treatment options besides surgical tumor removal and radiotherapy. To identify novel therapies for aggressive meningiomas, we established a multi-step drug screening workflow, focusing on targetable genes obtained from transcriptome data of highly aggressive grade 3 meningiomas. In vitro screening of 107 targeted drugs identified nine effective inhibitors. To study these drugs in a more natural environment, we established a standardized patient-derived tumor organoid (TO) model preserving accurately the original tissues genotype and phenotype. Individual drug responses were assessed in TOs from 60 molecularly characterized meningioma cases. Especially the FDA-approved epigenetic drug panobinostat demonstrated high antimeningioma efficacy in 70% of TOs, mediated through HDAC1/2 inhibition. In addition, treatment in an orthotopic in vivo model revealed a significantly improved survival. In a heavily pretreated patient suffering from an anaplastic meningioma, oral panobinostat treatment could delay the tumor growth rate. In search of the molecular mechanism underlying a potential intrinsic panobinostat resistance, we identified upregulation of the HDAC8-TGF{beta}-EMT axis in the TO model and subsequent HDAC8 depletion substantially increased the sensitivity to panobinostat. These data highlight the utility of personalized drug screenings on TOs to identify suitable drug targets and inhibitors for a more effective treatment of clinically aggressive meningiomas and help to advance our understanding of counteracting resistance mechanisms. One Sentence SummaryThis study provides strong in vitro, in vivo, ex vivo, and patient evidence for the efficacy of the HDACi panobinostat to treat clinically aggressive meningiomas and uncovered a potential intrinsic resistance mechanism by activation of the HDAC8-TGF{beta}-EMT axis.
Ultra-high dose rate radiotherapy with electrons and protons has shown potential for cancer treatment by effectively targeting tumors while sparing healthy tissues (FLASH effect). This study aimed to investigate the potential FLASH sparing effect of ultra-high-dose rate helium ion irradiation, focusing on acute brain injury and subcutaneous tumor response in a preclinical in vivo setting. Raster-scanned helium ion beams were used to compare the effects of standard dose rate (SDR at 0.2 Gy/s) and FLASH (at 141 Gy/s) radiotherapy on healthy brain tissue. Irradiation-induced brain injury was studied in C57BL/6 mice via DNA damage response, using nuclear {gamma}H2AX as a marker for double-strand breaks (DSB). The integrity of neurovascular and immune compartments was assessed through CD31+ microvascular density and activation of microglia/macrophages. Iba1+ ramified and CD68+ phagocytic microglia/macrophages were quantified, along with the expression of inducible nitric oxide synthetase (iNOS). Tumor response to SDR (0.2 Gy/s) and FLASH (250 Gy/s) radiotherapy was evaluated in A549 carcinoma model, using tumor volume and Kaplan-Meier survival as endpoints. The results showed that helium FLASH radiotherapy significantly reduced acute brain tissue injury compared to SDR, evidenced by lower levels of DSB and preserved neurovascular endothelium. Additionally, FLASH radiotherapy reduced neuroinflammatory signals compared to SDR, as indicated by fewer CD68+ iNOS+ microglia/macrophages. FLASH radiotherapy achieved tumor control comparable to that of SDR radiotherapy. This study is the first to report the FLASH sparing effect of raster scanning helium ion radiotherapy in vivo, highlighting its potential for neuroprotection and effective tumor control.
Paediatric medulloblastomas with chromothripsis are characterised by high genomic instability and are among the tumours with the worst prognosis. However, the determinants of their aggressiveness and the molecular makeup of chromothriptic medulloblastoma are not well understood. Here, we applied spatial transcriptomics to profile a cohort of 13 chromothriptic and non-chromothriptic medulloblastomas from the same molecular subgroup. Our data reveal a higher extent of spatial intra-tumour heterogeneity in chromothriptic medulloblastomas, which is associated with increased proliferation and stemness, but lower immune infiltration and differentiation. Spatial mapping of genetic subclones of the same tumour identify a regionally distinct architecture and clone-specific phenotypic features, with distinct degrees of differentiation, proliferation and immune infiltration between clones. We conducted temporal profiling of 11 patient-derived xenografts from chromothriptic medulloblastomas, covering the transition from the minimal residual disease stage to treatment-resistant regrown tumours. In chromothriptic medulloblastoma, an ecosystem of cells from multiple genetic clones resisting treatment and leading to relapse highlighted the importance of multi-clone interplay. Finally, we identified a potential role for tumour microtubes in treatment resistance in chromothriptic medulloblastoma, suggesting cell network communication as a putative target. HighlightsO_ST_ABSBiological insightsC_ST_ABSO_LIMedulloblastomas with chromothripsis are characterised by higher spatial intra-tumour heterogeneity, proliferation and stemness, but lower immune infiltration and differentiation, as compared with non-chromothriptic medulloblastomas C_LIO_LISpatially aware genetic clone assignment identifies phenotypic features such as degree of differentiation, proliferation and immune infiltration enriched in specific clones C_LIO_LICells from distinct genetic clones resist to treatment and give rise to relapse in patient-derived xenografts of medulloblastoma with chromothripsis C_LIO_LITumour microtubes point to putative molecular processes implicated in treatment resistance in chromothriptic medulloblastoma C_LI Technological advancesO_LIValidation of the spatial representation of patient-derived xenograft models, providing novel insights into the faithfulness of such models to study cancer C_LIO_LISpatial mapping of clones based on spatial transcriptomics and copy-number variant profiling C_LI
Radiotherapy can act as an in situ vaccine thereby activating tumor-specific immune responses that prevent tumor outgrowth in treated patients. While carbon ion radiotherapy has shown superior biophysical properties over conventional photon irradiation, the immunological effects induced have remained largely uncovered. The combination of radiotherapy with immune checkpoint inhibition (radioimmunotherapy) aims at further enhancement of anti-tumor immunity; however, studies on the immune cell composition in irradiated and distant tumors following radioimmunotherapy with carbon ions are scarce. We have established a bilateral tumor model by time shifted transplantation of murine, Her2+ EO771 tumor cells onto the flanks of immune competent mice followed by selective irradiation of the primal tumor, while sparing the consecutive tumor. We demonstrate that CTLA4-but not PD-L1-based radioimmunotherapy induces complete tumor rejection in our model. Intriguingly, local tumor control caused in situ immunization resulting even in eradication of non-irradiated, distant tumors. Moreover, cured mice were protected against EO771 rechallenge indicative of long lasting, tumor-protective immunological memory. Deconvolution of the treatment induced immunological effects by single cell RNA-sequencing (scRNA-seq) and concomitant flow cytometric analyses revealed in irradiated tumors predominating myeloid cells that developed into distinct tumor-associated macrophage clusters with upregulated expression of TNF and IL1 responsive genes, as well as activation of NK cells. Non-irradiated tumors showed higher frequencies of naive T cells in irradiated mice, which were activated when combined with CTLA4 blockade. In conclusion, radioimmunotherapy with carbon ions plus CTLA4 inhibition reshapes the tumor-infiltrating immune cell composition and can induce complete rejection even of non-irradiated tumors. Our data present a rationale to combine radiotherapy approach with CTLA4 blockade to achieve durable anti-tumor immunity. Evaluation of future radioimmunotherapy approaches should thus not only focus on the immunological impacts at the site of irradiation but should also consider systemic immunological effects that might affect outgrowth of non-irradiated tumors.