Maike de la Roche

Imaging reporter genes are essential tools in cancer research for monitoring tumor evolution, cell dissemination, gene activation and treatment response. However, germline reporter models typically rely on single imaging modalities operating over limited spatial scales. To address these limitations, we developed an inducible triple-reporter mouse model ( Rosa26 ^LSL-NRL ) that integrates three reporters for complementary imaging modalities, fluorescence, bioluminescence and positron emission tomography (PET), along with inducible Cre-lox functionality for precise spatiotemporal control of reporter expression in genetically engineered mouse models. Using a multiscale, multimodal approach, we visualize deep tissue oncogenesis in models of hepatocellular carcinoma and lung adenocarcinoma and, guided by whole-body imaging with bioluminescence and [ ¹⁸ F]tetrafluoroborate PET/magnetic resonance imaging (MRI), resolve cell−cell interactions within tumor microenvironments using in situ microscopy. This triple-reporter system enables multiscale investigation of biological processes within whole animals, facilitating sensitive, tissue-specific, in vivo cell tracking from whole-body to cellular resolution.

Cytotoxic CD8 ⁺ T lymphocytes (CTLs) efficiently eliminate infected and cancerous cells throughout the body. T cell receptor (TCR)-induced Hedgehog signalling contributes to CTL-mediated killing, but how the pathway is activated downstream of the TCR is unknown. Here, we show that extracellular calcium (Ca ²⁺ ) flux through L-type voltage-gated Ca ²⁺ (Ca _v 1) channels at the plasma membrane downstream of the TCR drives induction of the Hedgehog transcription factor Gli1, which is important for CTL killing in vitro and in vivo. This previously unknown non-canonical Hedgehog pathway is independent of canonical signalling and represents a primary mechanism of Gli1 induction in naive CD8 ⁺ T cells, whereas CTLs can also activate Gli1 via MAPK. We further show that Ca _v 1 channel-controlled Gli1 induction is functionally important for CTL killing in mice and humans and other cytotoxic lymphocytes. Notably, killing capacity can be amplified using a small molecule Ca _v 1 agonist or by overexpressing a gain-of-function Ca _v 1 subunit. These findings suggest a strategy to improve cytotoxic lymphocyte function in the clinic, including in CAR T cell therapy.

The Hedgehog (Hh) signaling pathway is aberrantly regulated in cancer. Hh inhibitors are successful in treating basal cell carcinoma (BCC) and Sonic Hedgehog–driven medulloblastoma but have largely failed in clinical trials of other solid cancers. We show that Hh inhibitor treatment specifically diminishes CD8 T cell migration into the tumor microenvironment, both in murine cancer models and resected BCCs from patients treated with the Smoothened (Smo) inhibitor vismodegib. Using small-molecule antagonists and genetic knockout models of key Hh signaling components, we demonstrate that the migration defect is mediated exclusively by the signal transducer Smo and not Hh ligands or Gli transcription factors. Smo acts noncanonically as a G protein–coupled receptor to regulate the migration of murine and human CD8 T cells via RhoA. Our data establish a link between Hh inhibition in vivo and the antitumor immune response and provide the basis for improved Hh targeting approaches for patients with cancer.

Venous tumour thrombus (VTT), where the primary tumour invades the renal vein and inferior vena cava, affects 10–15% of renal cell carcinoma (RCC) patients. Curative surgery for VTT is high-risk, but neoadjuvant therapy may improve outcomes. The NAXIVA trial demonstrated a 35% VTT response rate after 8 weeks of neoadjuvant axitinib, a VEGFR-directed therapy. However, understanding non-response is critical for better treatment. Here we show that response to axitinib in this setting is characterised by a distinct and predictable set of features. We conduct a multiparametric investigation of samples collected during NAXIVA using digital pathology, flow cytometry, plasma cytokine profiling and RNA sequencing. Responders have higher baseline microvessel density and increased induction of VEGF-A and PlGF during treatment. A multi-modal machine learning model integrating features predict response with an AUC of 0.868, improving to 0.945 when using features from week 3. Key predictive features include plasma CCL17 and IL-12. These findings may guide future treatment strategies for VTT, improving the clinical management of this challenging scenario.

We have developed and validated a highly specific, versatile antibody to the extracellular domain of human LGR5 (α-LGR5). α-LGR5 detects LGR5 overexpression in >90% of colorectal cancer (CRC), hepatocellular carcinoma (HCC) and pre-B-ALL tumour cells and was used to generate an Antibody-Drug Conjugate (α-LGR5-ADC), Bispecific T-cell Engager (α-LGR5-BiTE) and Chimeric Antigen Receptor (α-LGR5-CAR). α-LGR5-ADC was the most effective modality for targeting LGR5 ⁺ cancer cells in vitro and demonstrated potent anti-tumour efficacy in a murine model of human NALM6 pre-B-ALL driving tumour attrition to less than 1% of control treatment. α-LGR5-BiTE treatment was less effective in the pre-B-ALL cancer model yet promoted a twofold reduction in tumour burden. α-LGR5-CAR-T cells also showed specific and potent LGR5 ⁺ cancer cell killing in vitro and effective tumour targeting with a fourfold decrease in pre-B-ALL tumour burden relative to controls. Taken together, we show that α-LGR5 can not only be used as a research tool and a biomarker but also provides a versatile building block for a highly effective immune therapeutic portfolio targeting a range of LGR5-expressing cancer cells.

Cytotoxic T lymphocytes effectively eliminate cancer cells. Their abundance in the tumour microenvironment is one of the strongest pan-cancer predictors of clinical response. Here, we show that Hedgehog (Hh) signaling regulates T cell migration into tumours. Using conditional knockout mouse models of central Hh signaling components Ihh , Smo and Gli1 in CD8 T cells, we show that Smo deletion greatly impairs the anti-tumour response in vivo due to diminished CD8 T cell migration into the tumour microenvironment. The migration defect is mediated exclusively by Smo, both in in vivo cancer models and in vitro migration assays. This effect is independent of the canonical Hh pathway and relies on the GPCR function of Smo to regulate the migration of murine and human CD8 T cells via RhoA. Hh signaling is critical during embryonic development and adult stem cell homeostasis, but is also amplified in multiple cancer types. Hh inhibitors targeting SMO have been clinically-approved and shown efficacy in the treatment of Hh-driven basal cell carcinoma and medulloblastoma but have failed in clinical trials in other solid cancers with upregulated Hh signaling. We demonstrate that SMO inhibitors specifically decrease CD8 T cell migration into the tumour microenvironment, both in murine cancer models and resected BCCs from patients treated with the SMO inhibitor vismodegib, providing the first mechanistic explanation as to why Hh inhibitors have failed in solid cancers. Our data establishes a novel link between Hh inhibition in vivo and the anti-tumour immune response and reveals a fundamental mechanism controlling T cell migration. The work provides the basis for improved Hh targeting approaches in the clinic and new entry points into enhancing migration in T cell therapies.

In this article, I aim to give some pieces of career advise for young immunologists based on my own experiences.

Leucine-rich repeat-containing G-protein receptor 5 (LGR5) has been characterised as a stem cell and cancer stem cell marker. Previous analyses of LGR5 transcript levels indicate high level expression discriminates malignancies such as colorectal cancer (CRC) and pre-B acute lymphoblastic leukaemia (pre-B ALL) from healthy tissues suggesting LGR5 protein expression may provide a molecular handle for prognosis and treatment. We have developed highly specific, high affinity antibodies to the extracellular domain of human LGR5 (α-LGR5) that detect high LGR5 protein levels in colorectal cancer (CRC), hepatocellular carcinoma (HCC), and pre-B ALL. In contrast, there is low to undetectable levels of LGR5 protein in normal colon and rectal epithelia, liver, ovarian tissues, brain and immune cell types. LGR5 is rapidly internalised from the plasma membrane and trafficked to intracellular vesicular compartments including lysosomes. Treatment of high LGR5-expressing CRC and pre-B ALL cancer cell lines with an antibody-drug conjugate version of α-LGR5 (α-LGR5-ADC) lead to effective cell killing at nanomolar concentrations. Interventional treatment of pre-B ALL tumours with α-LGR5-ADC in vivo led to rapid tumour attrition. We further demonstrated the therapeutic utility of humanised α-LGR5 by using the corresponding scFv fragment for the generation of α-LGR5 chimeric antigen receptors (CARs) and a Bispecific T cell Engager (BiTE). α-LGR5-CAR-NK cells were effective at killing LGR5-expressing cells while α-LGR5/α-CD3 BiTEs induce T cell activation and killing of NALM6 cells by cytotoxic CD8 ⁺ T cells. Taken together, this study establishes α-LGR5-based therapeutic modalities that effectively discriminate and target CRC, HCC and pre-B ALL tumour cells. One Sentence Summary: We generated novel antibodies against the cancer cell marker LGR5, validated diagnostic use in prioritizing specific cancer types for targeting, and developed antibody-based therapeutics.