O2: TOWARDS A LIVING BIOBANK OF SURGICALLY-RELEVANT 3-DIMENSIONAL GLIOBLASTOMA STEM CELL MODELS TO EVALUATE NOVEL THERAPEUTICS AND INTERROGATE INTRATUMOURAL HETEROGENEITY

Introduction

Glioblastoma is the most common cancer arising within the brain. Despite surgery, followed by DNA-damaging chemoradiotherapy, average survival remains between 12-15 months. Unacceptable survival rates underline the need to develop preclinical research models which recapitulate features underpinning therapeutic resistance in patients, such as intratumoural heterogeneity and treatment resistant glioblastoma stem cell (GSC) subpopulations which demonstrate elevated DNA damage response (DDR) activity.

Method

Tumour specimens from patients were used to generate 2D and 3D scaffold-based GSC models, with a range of preclinical survival and molecular assays used to interrogate cancer biology and assess therapeutic responses.

Result

We have developed a ‘living biobank’ of 20+ ex-vivo GSC models which reflect key clinicopathological diversity. These models include residual disease models based on careful macrodissection of rare en-blocpartial lobectomy specimens to liberate parallel GSC lines from the tumour core and adjacent infiltrated brain, to represent cells typically left behind after surgery. Therapeutic strategies targeting fundamental DDR processes demonstrate preclinical efficacy, for example dual inhibition of ATR and the FA DNA damage repair pathways elicits profound radiosensitisation (sensitiser enhancement ratio of 3.23 (3.03-3.49, 95%-CI)) with evidence of delayed DNA damage repair on single-cell gel electrophoresis. Finally, characterisation of our surgically-relevant resected and residual models reveals numerous divergent properties including elevated stem cell marker expression in residual models (p=0.0021), which may partially explain treatment resistance in disease left behind after surgery.

Conclusion

Our living biobank represents a useful resource for preclinical glioblastoma research and demonstrates the value of partnership between surgeons and laboratory-based scientists.

Take-home message

Our living biobank represents a useful resource for preclinical glioblastoma research and demonstrates the value of partnership between surgeons and laboratory-based scientists.

TP1-3 Final phase of recruitment and statistics analysis plan for Dex-CSDH trial

Objectives

Review recruitment progression and statistical analysis plan for Dex-CSDH trial.

Design

A UK multi-centre, randomised, double-blind, placebo-controlled trial of dexamethasone versus placebo for CSDH.

Subjects

Symptomatic, adult CSDH patients admitted to a participating neurosurgical unit.

Methods

Trial participants receive a 2 week course of dexamethasone in addition to standard care, including surgery. The primary outcome measure is the modified Rankin Scale (mRS) at 6 months. An mRS of 0–3 requires the patient to be independently mobile and we have considered this a favourable outcome, with scores 4–6 (non-mobile) as unfavourable. The primary analysis will be performed on an intention-to-treat basis, estimating the absolute difference between the two treatment arms in the proportions achieving a favourable outcome. Secondary analysis will be done with an ordinal analysis of mRS scores and proportional odds logistic regression of the original mRS score adjusting for baseline covariates (age, GCS).

Results

629/750 patients (84%) have been recruited to the Dex-CSDH trial which is on-going as of 20-06-2018. Recruitment progress and follow-up at time of presentation will be reviewed alongside full statistical analysis plan.

Conclusions

The Dex-CSDH trial is drawing close to target following excellent recruitment across 22 UK centres. Transparent communication of the statistical analysis plan is essential prior to unblinding of the data. Up-to-date recruitment and primary endpoint completion rates will also be reviewed.