Tailored first-line and second-line CDK4-targeting treatment combinations in mouse models of pancreatic cancer

Abstract

ObjectiveExtensive molecular heterogeneity of pancreatic ductal adenocarcinoma (PDA), few effective therapies and high mortality make this disease a prime model for advancing development of tailored therapies. The p16-cyclin D-cyclin-dependent kinase 4/6-retinoblastoma (RB) protein (CDK4) pathway, regulator of cell proliferation, is deregulated in PDA. Our aim was to develop a novel personalised treatment strategy for PDA based on targeting CDK4.DesignSensitivity to potent CDK4/6 inhibitor PD-0332991 (palbociclib) was correlated to protein and genomic data in 19 primary patient-derived PDA lines to identify biomarkers of response. In vivo efficacy of PD-0332991 and combination therapies was determined in subcutaneous, intrasplenic and orthotopic tumour models derived from genome-sequenced patient specimens and genetically engineered model. Mechanistically, monotherapy and combination therapy were investigated in the context of tumour cell and extracellular matrix (ECM) signalling. Prognostic relevance of companion biomarker, RB protein, was evaluated and validated in independent PDA patient cohorts (>500 specimens).ResultsSubtype-specific in vivo efficacy of PD-0332991-based therapy was for the first time observed at multiple stages of PDA progression: primary tumour growth, recurrence (second-line therapy) and metastatic setting and may potentially be guided by a simple biomarker (RB protein). PD-0332991 significantly disrupted surrounding ECM organisation, leading to increased quiescence, apoptosis, improved chemosensitivity, decreased invasion, metastatic spread and PDA progression in vivo. RB protein is prevalent in primary operable and metastatic PDA and may present a promising predictive biomarker to guide this therapeutic approach.ConclusionThis study demonstrates the promise of CDK4 inhibition in PDA over standard therapy when applied in a molecular subtype-specific context.

Palbociclib, a selective CDK4/6 inhibitor, restricts cell survival and epithelial‐mesenchymal transition in Panc‐1 and MiaPaCa‐2 pancreatic cancer cells

“…27 PD-0332991 was reported to induce cell cycle arrest at the G1 phase, which led to cyclin D1 accumulation. Although each selected concentration of PD-0332991 induced cell cycle arrest at the G1 phase and decreased cell viability effectively, the Rb expression profile showed an important regulatory role to evaluate the sensitivity of cells against PD-0332991 treatment.…”

The Mini‐Organo: A rapid high‐throughput 3D coculture organotypic assay for oncology screening and drug development

“…This approach has been applied by us and many other groups to look at collagen fibre remodelling in organotypic studies as well as in normal and diseased tissues. 10,58,59 Finally, second harmonic generation (SHG) imaging is a label-free imaging technique that allows imaging of noncentrosymmetric entities such as collagen fibres. The generation of an SHG signal occurs when two photons with the same wavelength fuse into a single photon with half of the original wavelength upon interaction with a non-centrosymmetric entity.…”

“…Using SHG-generated images, orientation of collagen fibres can be assessed ( Figure 2G [bottom]). 10,[58][59][60][61] In addition, collagen fibre network organization can also be characterised using grey-level cooccurrence matrix (GLCM) analysis. 10,58,59,[61][62][63] This method provides a readout of the texture of a sample by quantifying the similarity between pixels across an image 64 (Figure 2H, data example shown is from blebbistatin treated CAFs [ Figure 4B]).…”

“…This allows for a quantitative morphometric analysis of the collagen fibres where the polarised colours reflect fibre thickness and packing (Figure G [top]). This approach has been applied by us and many other groups to look at collagen fibre remodelling in organotypic studies as well as in normal and diseased tissues . Finally, second harmonic generation (SHG) imaging is a label‐free imaging technique that allows imaging of noncentrosymmetric entities such as collagen fibres.…”

“…This approach allows for high resolution imaging of collagen fibres. Using SHG‐generated images, orientation of collagen fibres can be assessed (Figure G [bottom]) . In addition, collagen fibre network organization can also be characterised using grey‐level co‐occurrence matrix (GLCM) analysis .…”