The activity of FGFR and AR inhibitor combinatorial treatment in organotypic in vitro models of prostate cancer

Abstract

Androgen deprivation therapy (ADT) and androgen receptor (AR) antagonists, such as darolutamide remain as the first-line pharmacological strategy against prostate cancer (PC). Despite this, it has been estimated that 10-20 % PC patients progress to castration-resistant prostate cancer (CRPC), which is associated with a poor therapeutical response to treatment and resulting in less than 5-year survival. CRPC maintains its growth by switching AR-independent signalling pathways particularly, fibroblast growth factor receptor (FGFR)-signalling. Tumour microenvironment (TME), a physiologic 3D-environment of PC with tumour-stroma interaction and extracellular matrix (ECM), is known to contribute to the development of CRPC and AR-independence. The aim of the current thesis was to investigate the effectiveness of combining clinically utilized AR-inhibitor, darolutamide with a second-generation FGFR-inhibitor FIIN1. The second aim was to develop an in vitro PC model with key TME characteristics and evaluate the impact of 3D organotypic modelling, ECM and stromal component on treatment effectiveness. VCaP cell line was utilized as tumour and PF179T GFP cancer-associated fibroblasts (CAFs) as a stromal component. FIIN1 and darolutamide combination was studied in 2D, 3D and CAF-included co-culture models by evaluating proliferation, viability, and morphology of PC in response to treatment. The combination of inhibitors did not result in a distinct effect compared to inhibitors given separately. However, it was found that treatment effectivity decreased when given to more physiologic PC models. Specifically, 3D co-culture was associated with the lowest sensitivity to treatment, whereas simplistic 2D model was the most sensitive. All in all, results suggest the importance of combining both 3D modelling, ECM as well as tumour-stroma interaction in PC already in vitro, for achieving a good predictability in early-stages of drug screening. Furthermore, the developed 3D co-culture could be optimized for greater applicability and TME could be studied in-depth as a potential PC drug target.