Systematic review of radiomic biomarkers for predicting immune checkpoint inhibitor treatment outcomes

• Published in: Methods (San Diego, Calif.) Calif.), 2021-04, Vol.188, p.61-72
• Main Authors: Zhang, Chong, de A. F. Fonseca, Louise, Shi, Zhenwei, Zhu, Cheng, Dekker, Andre, Bermejo, Inigo, Wee, Leonard
• Format: Article
• Language: English
• Subjects: Computed tomography; Immune response; Immunotherapy; Radiomics; Solid cancers; Systematic review; Treatment response
• ISSN: 1046-2023; 1095-9130
• DOI: 10.1016/j.ymeth.2020.11.005

•Radiomics is quantitative image analysis that can predict immunotherapy response.•We found seven relevant studies, most of them focusing on non-small cell lung cancer.•Most reviewed studies had methodological shortcomings that limit their relevance.•Main issues were deficiencies in feature selection and lack of external validation.•Prospective studies that test the clinical utility of these models are needed. Systemic therapy agents targeting immune checkpoint inhibitors have been approved for use since 2011. This type of therapy aims to trigger a patient’s immune response to attack tumor cells, rather than acting against the tumor directly. Radiomics is an automated method of medical image analysis that is now being actively investigated for predictive markers of treatment response in immunotherapy. To conduct an early systematic review determining the current status of radiomic features as potential predictive markers of immunotherapy response. Provide a detailed critical appraisal of methodological quality of models, as this informs the degree of confidence about current reports of model performance. In addition, to offer some recommendations for future studies that could establish robust evidence for radiomic features as immunotherapy response markers. A PubMed citation search was conducted for publications up to and including April 2020, followed by full-text screening. A total of seven articles meeting the eligibility criteria were examined in detail for study characteristics, model information and methodological quality. The review was conducted in the Cochrane style but has not been prospectively registered. Results are reported following Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA) guidelines. A total of seven studies were examined in detail, comprising non-small cell lung cancer, metastatic melanoma and a diverse assortment of solid tumors. Methodological robustness of reviewed studies varied greatly. Principal shortcomings were lack of prospective registration, and deficiencies in feature selection and dimensionality reduction, model calibration, clinical utility and external validation. A few studies with overall moderate to good methodological quality were identified. These results suggest that current state-of-the-art performance of radiomics in regards to discrimination (area under the curve or concordance index) is in the vicinity of 0.7, but the very small number of studies to date prevents any conc