SONATA – Dr. Anna Krzyczmonik
Cancer encompasses over 100 distinct diseases characterized by uncontrolled cell proliferation and the ability to metastasize, representing the second leading cause of death worldwide. Tumour heterogeneity presents significant challenges for diagnosis, therapy, and patient stratification. Immune checkpoint blockade (ICB), particularly targeting the PD-1/PD-L1 axis, has emerged as a transformative modality in cancer immunotherapy, restoring immune surveillance and yielding clinical benefits in multiple tumour types. Despite these advances, response rates remain variable, and predictive biomarkers for patient selection are limited. This project aims to develop and systematically evaluate radioiodinated PD-L1 targeting ligands for targeted radionuclide therapy (TRT) and theranostic applications. The central therapeutic strategy employs iodine-131 to selectively deliver cytotoxic radiation to PD-L1 expressing tumour cells, leveraging both β⁻ and Auger electron emissions. Building on this foundation, the same molecular platform can be adapted for diagnostic imaging using iodine isotopes (iodine-123 or iodine-124) to non-invasively assess PD-L1 expression in vivo, enabling patient selection and treatment monitoring. A diverse set of ligands will be investigated, including monoclonal antibodies (mAbs), and small molecule inhibitors (SMIs). SMIs offer favourable pharmacokinetics, rapid tumour penetration, high stability, and lower production costs, while mAbs provide high specificity and established clinical efficacy. Radiolabelling strategies include direct iodination of SMIs, as well as conjugation via prosthetic groups to preserve biomolecule integrity. Novel click-chemistry prosthetic groups will be explored to facilitate pretargeting approaches, whereby an antibody modified with a chemical linker accumulates in the tumour before binding a radiolabelled small molecule, optimizing tumour dose while minimizing off-target radiation. Precursor compounds bearing organotin or boronic ester groups will be synthesized for both SMIs and prosthetic groups. Radiolabelling protocols will be optimized for high radiochemical yield and stability, and final products characterized using radio-HPLC, radio-TLC, ICP-MS, and NMR techniques. In vitro evaluation will assess binding specificity, affinity, internalization, and cytotoxicity in PD-L1 positive and negative cancer cell lines, like: B16-F10, HCC827, and C6. Advanced assays, such as MTS, clonogenic survival, alkaline comet, and γ-H2AX foci formation, will quantify therapeutic efficacy and DNA damage. Promising ligands will undergo in vivo and ex vivo evaluation in healthy and tumour-bearing mice, following ethical principles and 3R guidelines. Biodistribution, pharmacokinetics, metabolism, tumour uptake, and dosimetry will be assessed using PET, SPECT, Cherenkov imaging, γ-counting, and autoradiography. Further studies will explore labelling with alternative iodine isotopes and astatine-211 to expand theranostic versatility and enable α-emitter therapy. This multidisciplinary project integrates organic synthesis, radiochemistry, molecular imaging, and preclinical pharmacology to develop next-generation PD-L1-targeted radiopharmaceuticals. Outcomes will elucidate the influence of ligand structure, molecular size, and labelling strategy on biological performance, advancing knowledge of PD-L1 TRT, supporting the development of theranostic agents, and contributing to more personalized, effective, and safer cancer treatments.
