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Prediction of Undetectable Circulating Tumor DNA by Comprehensive Genomic Profiling Assay in Metastatic Prostate Cancer: The SCRUM-Japan MONSTAR SCREEN Project - Beyond the Abstract

Comprehensive genomic profiling using tumor tissues as well as circulating tumor DNA (ctDNA) has become a standard practice in the management of advanced solid tumors including prostate cancer.1 However, it is a clinical issue that successful assay results cannot be obtained in a small proportion of patients by comprehensive genomic profiling using ctDNA, mainly owing to undetectable ctDNA levels in samples.

We have prospectively performed next-generation sequencing analysis of ctDNA among patients with unresectable solid tumors using the commercial-based comprehensive genomic profiling test FoundationOne®Liquid CDx (F1LCDx®) in the SCRUM-Japan MONSTAR SCREEN project.2 Therefore, this study investigated the association between clinicopathological factors and undetectable ctDNA using a commercially available comprehensive genomic profiling assay in metastatic prostate cancer in a prospective observational study of the SCRUM-Japan MONSTAR SCREEN project.3

In this study, 175 patients with metastatic prostate cancer were analyzed. The number of bone metastases was associated with ctDNA detection. Among the patients with <4 bone metastases, the detection rate of ctDNA was 13.1%, while it was 1.1% in patients with ≥4 bone metastases. In addition, the ISUP grade group, PSA level at enrollment, and castration resistance status showed trends associated with ctDNA detection, although statistical significance was not reached. Then, an algorithm predicting ctDNA detection using these clinicopathological parameters was created and showed usefulness in predicting ctDNA detection.

Comprehensive genomic profiling tests are expensive, and reimbursement for this test is restricted in many healthcare systems. The Japanese healthcare system approves only a one-time comprehensive genomic profiling test per patient. Accordingly, the timing of ordering a comprehensive genomic profiling assay is important in daily practice. This study presented an algorithm predicting ctDNA detection using commonly available clinicopathological parameters including the number of bone metastases as well as ISUP grade group, PSA level at test, and castration resistance status. Using this algorithm, physicians could estimate the suitable timing to order comprehensive genomic profiling test using ctDNA including the F1LCDx® assay.

Written by: Masaki Shiota, MD, Associate Professor, Department of Urology, Kyushu University, Fukuoka, Japan

References:

  1. Mizuno K, Beltran H. Future directions for precision oncology in prostate cancer. Prostate. 2022;82:S86–S96.
  2. Nakamura Y, Fujisawa T, Taniguchi H, Bando H, Okamoto W, Tsuchihara K, Yoshino T, Ohtsu A. SCRUM-Japan GI-SCREEN, and MONSTAR-SCREEN: Path to the realization of biomarker-guided precision oncology in advanced solid tumors. Cancer Sci. 2021;112:4425–4432.
  3. Shiota M, Matsubara N, Kato T, Eto M, Osawa T, Abe T, Shinohara N, Nishimoto K, Yasumizu Y, Tanaka N, Oya M, Fujisawa T, Horasawa S, Nakamura Y, Yoshino T, Nonomura N. Prediction of undetectable circulating tumor DNA by comprehensive genomic profiling assay in metastatic prostate cancer: the SCRUM-Japan MONSTAR SCREEN project. World J Urol. 2024;42:526

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