A TRAIL-R1-specific ligand in combination with doxorubicin selectively targets primary breast tumour cells for apoptosis

Development of a patient-derived explant model for prediction of drug responses in endometrial cancer

OBJECTIVE

To undertake a pilot study to develop a novel Patient-Derived-Explant (PDE) model system for use in endometrial cancer (EC) that is capable of monitoring differential drug responses in a pre-clinical setting.

METHODS

Fresh tumour was obtained post-hysterectomy from 27 patients with EC. Tumours were cut into 1-3 mm³ explants that were cultured at the air-liquid interface for 16-24 h in culture media. Explants were cultured in different media conditions to optimise viability. Explants were also treated with carboplatin/paclitaxel or pembrolizumab for 24 h and processed into histology slides. Multiplexed immunofluorescence for Ki67 (proliferation marker), cPARP (apoptosis marker) and CAM 5.2 (tumour mask) was performed followed by image analysis and quantitation of biomarker expression.

RESULTS

EC samples are amenable to PDE culture with preserved histological architecture and PDE viability for up to 48 h, with the addition of autologous serum in culture media facilitating EC-PDE viability. Our PDE platform provides evidence of differential drug-response to conventional chemotherapeutics and immune checkpoint inhibition, and these responses can be assessed in the context of a preserved tumour microenvironment.

CONCLUSIONS

Our PDE platform represents a rapid, low-cost pre-clinical model which can be easily integrated into drug development pipelines. PDE culture preserves original tumour architecture and enables evaluation of spatial relationships in the tumour microenvironment. PDE culture has the potential for personalised drug-testing in a pre-clinical setting which is increasingly important in an era of personalised medicine in the treatment of EC.

Patient-derived explants (PDEs) as a powerful preclinical platform for anti-cancer drug and biomarker discovery

Preclinical models that can accurately predict outcomes in the clinic are much sought after in the field of cancer drug discovery and development. Existing models such as organoids and patient-derived xenografts have many advantages, but they suffer from the drawback of not contextually preserving human tumour architecture. This is a particular problem for the preclinical testing of immunotherapies, as these agents require an intact tumour human-specific microenvironment for them to be effective. In this review, we explore the potential of patient-derived explants (PDEs) for fulfilling this need. PDEs involve the ex vivo culture of fragments of freshly resected human tumours that retain the histological features of original tumours. PDE methodology for anti-cancer drug testing has been in existence for many years, but the platform has not been widely adopted in translational research facilities, despite strong evidence for its clinical predictivity. By modifying PDE endpoint analysis to include the spatial profiling of key biomarkers by using multispectral imaging, we argue that PDEs offer many advantages, including the ability to correlate drug responses with tumour pathology, tumour heterogeneity and changes in the tumour microenvironment. As such, PDEs are a powerful model of choice for cancer drug and biomarker discovery programmes.

Ex Vivo Explant Cultures of Non-Small Cell Lung Carcinoma Enable Evaluation of Primary Tumor Responses to Anticancer Therapy

To improve treatment outcomes in non-small cell lung cancer (NSCLC), preclinical models that can better predict individual patient response to novel therapies are urgently needed. Using freshly resected tumor tissue, we describe an optimized ex vivo explant culture model that enables concurrent evaluation of NSCLC response to therapy while maintaining the tumor microenvironment. We found that approximately 70% of primary NSCLC specimens were amenable to explant culture with tissue integrity intact for up to 72 hours. Variations in cisplatin sensitivity were noted with approximately 50% of cases responding ex vivo Notably, explant responses to cisplatin correlated significantly with patient survival (P = 0.006) irrespective of tumor stage. In explant tissue, cisplatin-resistant tumors excluded platinum ions from tumor areas in contrast to cisplatin-sensitive tumors. Intact TP53 did not predict cisplatin sensitivity, but a positive correlation was observed between cisplatin sensitivity and TP53 mutation status (P = 0.003). Treatment of NSCLC explants with the targeted agent TRAIL revealed differential sensitivity with the majority of tumors resistant to single-agent or cisplatin combination therapy. Overall, our results validated a rapid, reproducible, and low-cost platform for assessing drug responses in patient tumors ex vivo, thereby enabling preclinical testing of novel drugs and helping stratify patients using biomarker evaluation. Cancer Res; 77(8); 2029-39. ©2017 AACR.

Resistance to HSP90 inhibition involving loss of MCL1 addiction

Inhibition of the chaperone heat-shock protein 90 (HSP90) induces apoptosis, and it is a promising anti-cancer strategy. The mechanisms underpinning apoptosis activation following HSP90 inhibition and how they are modified during acquired drug resistance are unknown. We show for the first time that, to induce apoptosis, HSP90 inhibition requires the cooperation of multi BH3-only proteins (BID, BIK, PUMA) and the reciprocal suppression of the pro-survival BCL-2 family member MCL1, which occurs via inhibition of STAT5A. A subset of tumour cell lines exhibit dependence on MCL1 expression for survival and this dependence is also associated with tumour response to HSP90 inhibition. In the acquired resistance setting, MCL1 suppression in response to HSP90 inhibitors is maintained; however, a switch in MCL1 dependence occurs. This can be exploited by the BH3 peptidomimetic ABT737, through non-BCL-2-dependent synthetic lethality.