Proposing Response Evaluation Criteria in Solid Tumors Based on Genomic Profiling or Genomic RECIST: A Retrospective Study on the Liquid Biopsy Results of 29 Cancer Patients

Author(s): Khin Zay Yar Myint, Masamori Shimabuku, Kenichi Kashihara, Ruriko Horio, Munehisa Kaneda, Yoko Shimizu, Junichi Taguchi

Tumor response and disease progression are assessed using imaging technologies. However, these technologies fail to detect tumor responses at the molecular level and clonal evolution. A potential surrogate for such parameters is using Circulating Tumor DNA (ctDNA). This study aimed to examine the quantity and composition of the ctDNA results of 29 cancer patients before and after Dendritic Cell (DC) immunotherapy and develop criteria to evaluate the molecular response to treatment based on these results. We categorized the patients into four categories based on percent changes in the total ctDNA compared with the baseline ctDNA titers, and this response assessment was termed genomic response evaluation criteria in solid tumors or gRECIST. Even those who are clinically evaluated as having a good response might harbor unfavorable tumor responses at the molecular level. Newly formed ctDNA levels can be the most prognostic parameter in tumor progression or the treatment response, while ctDNA clearance and the decline or rise in existing ctDNA did not change significantly in genomic response categories (gRECIST). More research is needed to support the clinical use of ctDNA in precision oncology and personalized cancer treatment.