Cancer Research and Treatment

Original Articles

Gastrointestinal cancer

Longitudinal Comparative Analysis of Circulating Tumor DNA and Matched Tumor Tissue DNA in Patients with Metastatic Colorectal Cancer Receiving Palliative First-Line Systemic Anti-Cancer Therapy: Seung-been Lee, Ji-Won Kim, Hong-Geun Kim, Sung-Hyun Hwang, Kui-Jin Kim, Ju Hyun Lee, Jeongmin Seo, Minsu Kang, Eun Hee Jung, Koung Jin Suh, Se Hyun Kim, Jin Won Kim, Yu Jung Kim, Jee Hyun Kim, Nak-Jung Kwon, Keun-Wook Lee; Cancer Res Treat. 2024;56(4):1171-1182. Published online April 29, 2024; DOI: https://doi.org/10.4143/crt.2024.016

Abstract PDF Supplementary Material PubReader ePub: Purpose
This study aimed to compare tumor tissue DNA (ttDNA) and circulating tumor DNA (ctDNA) to explore the clinical applicability of ctDNA and to better understand clonal evolution in patients with metastatic colorectal cancer undergoing palliative first-line systemic therapy.
Materials and Methods
We performed targeted sequencing analysis of 88 cancer-associated genes using germline DNA, ctDNA at baseline (baseline-ctDNA), and ctDNA at progressive disease (PD-ctDNA). The results were compared with ttDNA data.
Results
Among 208 consecutively enrolled patients, we selected 84 (41 males; median age, 59 years; range, 35 to 90 years) with all four sample types available. A total of 202 driver mutations were found in 34 genes. ttDNA exhibited the highest mutation frequency (n=232), followed by baseline-ctDNA (n=155) and PD-ctDNA (n=117). Sequencing ctDNA alongside ttDNA revealed additional mutations in 40 patients (47.6%). PD-ctDNA detected 13 novel mutations in 10 patients (11.9%) compared to ttDNA and baseline-ctDNA. Notably, seven mutations in five patients (6.0%) were missense or nonsense mutations in APC, TP53, SMAD4, and CDH1 genes. In baseline-ctDNA, higher maximal variant allele frequency (VAF) values (p=0.010) and higher VAF values of APC (p=0.012), TP53 (p=0.012), and KRAS (p=0.005) mutations were significantly associated with worse overall survival.
Conclusion
While ttDNA remains more sensitive than ctDNA, our ctDNA platform demonstrated validity and potential value when ttDNA was unavailable. Post-treatment analysis of PD-ctDNA unveiled new pathogenic mutations, signifying cancer’s clonal evolution. Additionally, baseline-ctDNA’s VAF values were prognostic after treatment.

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Effector Function Characteristics of Exhausted CD8+ T-Cell in Microsatellite Stable and Unstable Gastric Cancer: Dong-Seok Han, Yoonjin Kwak, Seungho Lee, Soo Kyung Nam, Seong-Ho Kong, Do Joong Park, Hyuk-Joon Lee, Nak-Jung Kwon, Hye Seung Lee, Han-Kwang Yang; Cancer Res Treat. 2024;56(4):1146-1163. Published online April 12, 2024; DOI: https://doi.org/10.4143/crt.2024.317

Abstract PDF PubReader ePub

Purpose
Gastric cancer exhibits molecular heterogeneity, with the microsatellite instability–high (MSI-H) subtype drawing attention for its distinct features. Despite a higher survival rate, MSI-H gastric cancer lack significant benefits from conventional chemotherapy. The immune checkpoint inhibitors, presents a potential avenue, but a deeper understanding of the tumor immune microenvironment of MSI-H gastric cancer is essential.
Materials and Methods
We explored the molecular characteristics of CD8+ T-cell subtypes in three MSI-H and three microsatellite stable (MSS) gastric cancer samples using single-cell RNA sequencing and spatial transcriptome analysis.
Results
In MSI-H gastric cancer, significantly higher proportions of effector memory T cell (Tem), exhausted T cell (Tex), proliferative exhausted T cell (pTex), and proliferative T cell were observed, while MSS gastric cancer exhibited significantly higher proportions of mucosal-associated invariant T cell and natural killer T cell. In MSI-H gastric cancer, Tex and pTex exhibited a significant upregulation of the exhaustion marker LAG3, as well as elevated expression of effector function markers such as IFNG, GZMB, GZMH, and GZMK, compared to those in MSS gastric cancer. The interferon γ (IFN-γ) signaling pathway of Tex and pTex was retained compared to those of MSS gastric cancer. The spatial transcriptome analysis demonstrates the IFN-γ signaling pathway between neighboring Tex and malignant cell, showcasing a significantly elevated interaction in MSI-H gastric cancer.
Conclusion
Our study reveals novel finding indicating that IFN-γ signaling pathway is retained in Tex and pTex of MSI-H gastric cancer, offering a comprehensive perspective for future investigations into immunotherapy for gastric cancer.

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Simvastatin induces ferroptosis and activates anti-tumor immunity to sensitize anti-PD-1 immunotherapy in microsatellite stable gastric cancer
Yumei Ning, Shilin Fang, Runan Zhang, Jun Fang, Kun Lin, Yang Ding, Haihang Nie, Jingkai Zhou, Qiu Zhao, Hengning Ke, Haizhou Wang, Fan Wang
International Immunopharmacology.2024; 142: 113244. CrossRef

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