Dr Ashleigh Parkin

Abstract

Dual inhibition of JAK and Src: A novel and synergistic combination to target pancreatic tumours and their microenvironment

Parkin A, Froio D, Vogel N, Man J, Murphy K, Deng N, Yin J, Croucher D, Samra JS, Gill AJ, Timpson P, and Pajic M.

The Kinghorn Cancer Centre, Cancer Division, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia

Pancreatic cancer (PC) has a 5-year survival of only 6%, and persists as the 4th most common cause of cancer-related death in Western societies. A more tailored treatment approach may be beneficial as the current standard-of-care therapies offer only a modest increase in overall patient survival. Recent large-scale genomic studies have revealed that the Src/JAK/STAT3 signalling pathway is deregulated in up to 35% of PC, and is yet to be systematically examined in this disease. Consequently, we hypothesized that targeting pancreatic tumours with activated JAK/STAT3 signalling with selective JAK1/JAK2 or JAK3 inhibitors and an Src inhibitor represents a promising novel therapeutic strategy for this disease.

To systematically examine the in vitro and in vivo efficacy of individualised therapeutic strategies involving selective JAK1/2 and Src inhibitors. And to investigate underlying mechanisms of efficacy in the context of the complex tumour microenvironment.

We utilized well-annotated patient-derived cell-line models (ICGC), along with cell-lines generated from the aggressive KPC mouse model. Using these pre-clinical models we assessed the in vitro efficacy of therapeutic strategies involving Src/JAK/STAT3 inhibition, using cell proliferation assays, 2D-drug synergy screens, 3D organotypic invasion assays, and 3D organoid cultures. Extracellular matrix integrity post-treatment was assessed using second-harmonic generation (SHG) imaging and picrosirius staining. Multiplex cytokine arrays, and single-cell transcriptomics were used to delineate mechanisms and assess pathway modulation following treatment. To examine in vivo efficacy, we utilized a syngeneic KPC mouse model as well as patient-derived xenograft models.

We show that selected JAK and Src-inhibitors inhibit cell proliferation in candidate PDCLs and KPC lines, characterized by activated Src/JAK/STAT3 signalling, with combination therapy being synergistic in the majority of these cell-lines. Cell invasion was significantly inhibited in organotypic matrices, and there was decreased collagen contractility, and reduced fibrillar collagen coverage. We show significant changes in cytokine production, and have also identified several pathways that are modulated following treatment, via the use of single-cell transcriptomics. We also demonstrate the in vivo efficacy of these therapies, and show their effects on modulating the tumour microenvironment.

Our findings demonstrate the potential for tailored therapeutic strategies involving Src/JAK/STAT3 inhibition in PC, and suggest that therapeutic efficacy may be the result of targeting both tumour cells and the tumour microenvironment, as well as by overcoming tumour-induced immunosuppression.