Radiosensitising Rectal Cancer via Stem Cell Transdetermination

Main Applicant: Chris Tape (UCL)
Co-applicant(s): Julian Downward (Crick)

This CRUK City of London RadNet project aims to improve radiotherapy responses in rectal cancer by targeting stem cell plasticity. Only ~15% of rectal cancer patients fully respond to current chemoradiotherapy, highlighting the need for better treatments. Using high-throughput single-cell analysis of patient-derived colorectal cancer organoids, we previously discovered colonic epithelial cells exist on a continuum of stem cell states—from chemo- and radio-sensitive proliferative colonic stem cells (proCSC) to chemo- and radio-resistant revival colonic stem cells (revCSC). We also found that cancer-associated fibroblasts (CAFs) can shift proCSC to revCSC state, and that this transition is driven by decreased PI3K signalling and increased YAP signalling.

This CRUK City of London RadNet project will test whether manipulating these pathways can transdeterminate radioresistant revCSC back into radiosensitive proCSC. Using a panel of rectal cancer patient organoids, we will systematically apply chemotherapy, radiotherapy, and novel targeted compounds that activate PI3K, and inhibit YAP and KRAS signalling. High-dimensional single-cell phenotyping using TOBis mass cytometry and geodesic sinkhorn optimal transport will track how each treatment alters stem cell states and signalling responses. This approach will generate a comprehensive ‘phenoscape’ of rectal cancer plasticity, identifying patient-specific vulnerabilities and informing future pre-clinical development of stem cell–targeted radiosensitisation strategies.

Establishment of a Whole-Genome CRISPRa Gain-of-Function Screening Pipeline to Identify Novel Regulators of Radiation Response

Main Applicant: Graeme Hewitt, KCL
Co-applicant(s): Kasper Fugger, UCL

A collaborative research project led by Graeme Hewitt and Kasper Fugger has received funding from the CRUK CoL RadNet Development Fund to develop a next-generation CRISPR activation (CRISPRa) screening platform. The project aims to tackle one of the major challenges in oncology: resistance to ionising radiation (IR), a leading cause of cancer treatment failure and mortality.

While CRISPR-Cas9 knockout screens have significantly advanced our understanding of how gene loss contributes to radio-resistance, they only reveal part of the story. Gene upregulation—where increased gene expression helps tumours evade therapy—also plays a crucial role. This newly funded initiative will establish a robust CRISPRa pipeline to systematically identify genes whose activation drives resistance to IR.

Leveraging the complementary screening expertise of the Hewitt and Fugger labs, the project will enable high-throughput, genome-wide interrogation of gene activation events. The goal is to uncover novel resistance mechanisms and identify new, druggable targets for improved cancer therapies.

By integrating CRISPRa into radiotherapy research, this project fills a critical gap in current functional genomics strategies and represents a key step toward more comprehensive, personalised approaches to overcoming treatment resistance.

Combining CAR-T cell therapy with low dose radiotherapy for local and metastatic tumour control in the childhood cancer rhabdomyosarcoma

Main Applicant: John Anderson (UCL)
Co-applicant(s): Peter Gawne (QMUL), Jane Sosabowski (QMUL)

Our research has shown in mouse models of the childhood cancer, neuroblastoma, that a single low dose treatment of radiotherapy, when given 24 hours before CAR-T cell infusion, dramatically increases tumour shrinkage. Moreover, this effect is manifest in non-irradiated as well as irradiated tumour sites. To facilitate the incorporation of this intervention in a forthcoming paediatric phase I trial in all childhood solid tumours, we will confirm this phenomenon in another childhood tumour rhabdomyosarcoma – as well as investigating the mechanism of the immune priming.

The Impact of neutrophils on TME’s response to radiotherapy

Main applicant: Ilaria Malanchi (Crick)
Co-Applicant(s): Erik Sahai, (Crick), Kairbaan Hodivala-Dilke (Barts)

We will develop multiplexed spatial characterization of the tumour microenvironment (TME) upon radiotherapy in both primary tumours and metastases growing in the lung or in the liver. The development of the multiplexed imaging pipeline will initially use tissues from experiments focusing on the interplay between neutrophils and breast cancer metastasis growing either lung or liver after radiotherapy. Once established, the pipeline will be applied to lung
tumours +/- radiotherapy +/- vascular targeting therapy. The protocol will be made available to all CoL RadNet researchers prior to publication.

Discerning the role of cancer associated fibroblasts in modulating effective immune responses to RT

Main applicant: Jacqui Shields (KCL)
Co-Applicant(s): Mirjana Efremova (QMUL)

While RT can induce immunogenic cell death capable of stimulating potent anti-tumour immunity, signals within the tumour microenvironment (TME) can override this. Cancer associated fibroblasts are emerging as important participants in determining therapy responses, but whether they support or inhibit RT-induced immunity remains unclear. Here we will determine the impact of RT on CAF phenotype functionality, and immune interactions.

One of the major features of the glioblastoma is its marked therapeutic resistance. Glioma cells invade normal brain inducing endothelial cell proliferation and causing blood–brain barrier (BBB) disruption. Despite showing promising results in patients, the delivery of Chimeric Antigen Receptor (CAR) T cells therapy is limited by the heterogeneity of the BBB disruption. Our aim is to show that a novel non-invasive MRI technique, sensitive to BBB integrity, is a potential biomarker of low-density tumor cell infiltration that could be used to detect the biological response to radiotherapy and to improve treatment planning.

We will be starting Radiant-BC trial, a multi-centre trial combining durvalumab with stereotactic radiosurgery (SRS) and standard systemic therapies in patients with brain metastases secondary to breast cancer (see appendix). We propose to use multispectral immunofluorescence (VECTRA3 platform) with computation analysis to decipher the tumour microenvironment of the tumours from these patients. We will assess the expression of various immune and myeloid-derived suppressor cells (MDSC) markers in order to uncover potential predictive biomarkers for these patients. This analysis will be correlated with peripheral immune markers before and after SRS and immunotherapy treatments as well as the treatment efficacy and immune-related toxicities.

We have compelling preliminary data demonstrating that genetic loss of endothelial cell-FAK (EC-FAK) does not affect angiogenesis or drug delivery but enhances the efficacy of DNA-damaging therapy, including chemo- and radiotherapy via therapy-induced altered paracrine,(a.k.a angiocrine) signals (Tavora et al., Nature 2014). We have developed novel Vegf-r2-siFAK RNA aptamers that specifically delete FAK in ECs. Here, we will test the efficacy of combination treatment of EC-specific FAK depleting aptamers with radiotherapy for improved NSCLC treatment.