Ex-vivo efficacy assessment of immunotherapy and targeted inhibitors for personalised treatment of metastatic melanoma

Introduction: Functional ex-vivo drug screening on patient-derived tissue offers a direct readout of personalised drug efficacy, complementing molecular profiling which identifies a fraction of likely responders to targeted inhibitors or immune checkpoint blockers (ICBs). Metastatic melanoma and renal cell carcinoma (RCC) are complementary exemplars: both are immunologically active solid tumours treated with overlapping ICBs and class-specific targeted inhibitors, yet response remains highly variable. This project evaluated ex-vivo 2D and 3D culture models for personalised drug efficacy of both drug types.

Methods: Immunofluorescence microscopy (IFM) based drug efficacy assessment protocols were optimised using cell lines. Metastatic melanoma lymph nodes (n=12) and primary RCC tumours (n=20), with matched blood samples, were collected. Tumour-dissociated cells were cultured, fixed, and stained in 384-well drug plates to assess viability of malignant and immune cells. Personalised drug efficacy was determined by IC50 and AUC values. Patient-derived cells (2D) or spheroids (3D) were co-cultured with matched PBMCs for ICB assessment. Immune-malignant cell attachment was analysed as a measure of ICB-induced interactions.

Results: QC-approved endpoint data achieved in ≥50% of patients for both cohorts. Distinct patient and drug clusters were identified, and personalised drug response profiles were generated. The highest sensitivity was observed for trametinib (MEK inhibitor, 75%) in melanoma, and for SHF_1556_AA008 (pan-Calcitonin Receptor Like Receptor inhibitor, 100%) in the RCC patients. Immune-malignant cell attachment was quantifiable in both 2D and 3D co-cultures, with measurable ICB-induced differences in attachment versus control detected in both formats.

Conclusion: The project showed experimental feasibility of IFM-based ex-vivo platform for assessing both targeted inhibitor and ICB efficacy on patient-derived melanoma and RCC tissue. Quantifiable immune-tumour interactions extend the platform beyond targeted agents to functional ICB testing, a key challenge for current precision oncology platforms. These findings justify a larger prospectively designed study linking ex-vivo drug response to clinical outcomes.