Online

ESTRO 2020

Session Item

Saturday
November 28
10:30 - 11:30
Clinical Stream 1
Proffered papers 3: Sarcoma
1190
Proffered Papers
Clinical
10:30 - 10:40
A sarcoma hypoxia signature (nanoString® assay) validates in the phase III VorteX radiotherapy trial
Laura Forker, United Kingdom
OC-0086

Abstract

A sarcoma hypoxia signature (nanoString® assay) validates in the phase III VorteX radiotherapy trial
Authors: Becky Bibby.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom), Lucinda Billingham.(University of Birmingham, Cancer Research UK Clinical Trials Unit, Birmingham, United Kingdom), Ananya Choudhury.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom), Laura FORKER.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom), Piers Gaunt.(University of Birmingham, Cancer Research UK Clinical Trials Unit, Birmingham, United Kingdom), Joely Irlam.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom), Michael Leahy.(The Christie NHS Foundation Trust, Medical Oncology, Manchester, United Kingdom), Martin Robinson.(University of Sheffield, Academic Unit of Clinical Oncology, Sheffield, United Kingdom), Patrick Shenjere.(The Christie NHS Foundation Trust, Histopathology, Manchester, United Kingdom), Helen Valentine.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom), Catharine West.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom), James Wylie.(The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom), Lingjian Yang.(University of Manchester, Translational Radiobiology, Manchester, United Kingdom)
Show Affiliations
Purpose or Objective

Soft tissue sarcomas (STS) are a rare group of tumours encompassing ~50 malignant, heterogeneous subtypes. Localised disease is managed with surgery ± radiotherapy. Neoadjuvant radiotherapy response is varied and despite high metastatic recurrence rates, there is no definite overall survival benefit from the addition of systemic chemotherapy.

Each subtype is very rare; therefore, biomarkers of adverse biological features present across subtypes might be more successful in selecting high-risk patients for clinical trials. Tumour hypoxia is associated with poor radiotherapy response and metastasis. We previously derived a 24-gene STS hypoxia signature that was prognostic in two independent cohorts.

The study aims were (1) signature validation in a new whole transcriptome cohort (2) assay development for pre-treatment biopsies (3) assay validation.

Material and Methods

Three cohorts were used (1) VorteX n=203 (2) single centre retrospective n=165 (3) MCRC Biobank n=28. VorteX was a randomised phase III trial comparing radiotherapy volumes in adults with localised extremity STS. Validation cohorts included mainly high-risk patients (85% high-grade).

Whole transcriptome RNA-sequencing data (Illumina HiSeq4000) were generated from fresh frozen tumour samples for VorteX. Two targeted assays (Taqman® array cards and nanoString®) were compared in formalin-fixed, paraffin-embedded (FFPE) biopsies. Prognostic validation of the nanoString® assay was performed in FFPE samples from the retrospective and VorteX cohorts. Intra-tumour heterogeneity was assessed in patients (n=10) with multiple biopsies and compared with CAIX expression.


Results

In the RNA-sequencing VorteX cohort, data were generated for 125/140 patients with available tissue. There was a trend towards poor disease-free survival (DFS) in patients with hypoxic tumours (HR 1.68 95% CI 0.95-2.98 p=0.061).

Taqman® array cards and nanoString® demonstrated excellent pass rates and reproducibility. The nanoString® was more sensitive, required lower input and can measure more genes simultaneously. The gene signature showed considerably less intra-tumour heterogeneity than a single marker (figure 1).

The nanoString® assay produced a result for 126/127 (99.2%) and 154/159 (96.9%) of patients with sufficient RNA yield and classified 41.3% and 44.8% of samples as hypoxic from the retrospective and VorteX cohorts, respectively. In a univariate analysis patients with hypoxic tumours had worse disease free survival in both cohorts (retrospective HR 2.302 95% CI 1.182-4.486 p=0.0083, VorteX HR 1.687 95% CI 1.013-2.81 p=0.0377) (figure 2).


Conclusion

A hypoxia signature nanoString® assay with excellent technical performance is prognostic in two independent cohorts of patients with high-grade tumours, including the phase III VorteX radiotherapy trial. The assay could identify high-risk patients for adjuvant chemotherapy trials.