Tumour growth rate improves tumour assessment and first-line systemic treatment decision-making for immunotherapy in patients with liver metastatic uveal melanoma

Background The RECIST-based response variably matches the clinical benefit of systemic therapies for liver metastatic uveal melanoma (LMUM). The aims were to determine whether the tumour growth rate (TGR) can help predict the survival in patients with LMUM and to provide information for the management of first-line systemic treatment. Methods This retrospective study included 147 (training: n = 110, validation: n = 37) patients with LMUM treated with first-line systemic treatment between 2010 and 2021. Two TGR-derived parameters were calculated, TGR 0 and TGR 3m . Multivariate Cox analyses identified independent predictors of progression-free survival (PFS) and overall survival (OS). Results TGR 3m was a strong independent prognostic factor of PFS and OS ( p < 0.001). The RECIST-based response was no longer significant in the OS analyses. Only immunotherapy regimens correlated with higher OS (HR = 0.2; 95% CI, 0.1–0.5; p < 0.001) in the low-TGR 3m (≤50%/m) subgroup. These findings were confirmed in the validation cohort. TGR 0 , disease-free interval (DFI), and the sum of target lesions at baseline were predictive factors of low TGR 3m . Discussion The use of TGR 3m would improve tumour assessment by identifying patients who would benefit from first-line immunotherapy regimens despite PD. TGR 0 , DFI and the sum of target lesions were correlated with TGR 3m , which can support first-line treatment decision-making for immunotherapy.