Circulating tumor DNA (ctDNA) may aid in personalizing ovarian cancer therapeutic options. Here, we aimed to assess the clinical utility of serial ctDNA testing using tumor-naïve, small-sized next-generation sequencing (NGS) panels. A total of 296 patients, including 201 with ovarian cancer and 95 with benign or borderline disease, were enrolled. Samples were collected at baseline (initial diagnosis or surgery) and every 3 months after that, resulting in a total of 811 blood samples. Patients received adjuvant therapy based on the current standard of care. Cell-free DNA was extracted and sequenced using an NGS panel of 9 genes: TP53, BRCA1, BRCA2, ARID1A, CCNE1, KRAS, MYC, PIK3CA, and PTEN. Pathogenic somatic mutations were identified in 69.2% (139/201) of patients with ovarian cancer at baseline but not in those with benign or borderline disease. Detection of ctDNA at baseline and/or at 6 months follow-up was predictive of progression-free survival (PFS). PFS was significantly poorer in patients with detectable pathogenic mutations at baseline that persisted at follow-up than in patients that converted from having detectable ctDNA at baseline to being undetectable at follow-up; survival did not differ between patients without pathogenic ctDNA mutations in baseline or follow-up samples and those that converted from ctDNA positive to negative. Disease recurrence was also detected earlier with ctDNA than with conventional radiologic assessment or CA125 monitoring. These findings demonstrate that serial ctDNA testing could effectively monitor patients and detect minimal residual disease, facilitating early detection of disease progression and tailoring of adjuvant therapies for ovarian cancer treatment. Significance: In ovarian cancer, serial circulating tumor DNA testing is a highly predictive marker of patient survival, with a significantly improved recurrence detection lead time compared with conventional monitoring tools.

Purpose: Patient-specific molecular alterations leading to PARP inhibitor (PARPi) resistance are relatively unexplored. In this study, we analyzed serially collected circulating tumor DNA (ctDNA) from patients with BRCA1/2 mutations who received PARPis to investigate the resistance mechanisms and their significance in postprogression treatment response and survival. Experimental Design: Patients were prospectively enrolled between January 2018 and December 2021 (NCT05458973). Whole-blood samples were obtained before PARPi administration and serially every 3 months until progression. ctDNA was extracted from the samples and sequenced with a 531-gene panel; gene sets for each resistance mechanism were curated. Results: Fifty-four patients were included in this analysis. Mutation profiles of genes in pre-PARPi samples indicating a high tumor mutational burden and alterations in genes associated with replication fork stabilization and drug efflux were associated with poor progression-free survival on PARPis. BRCA hypomorphism and reversion were found in 1 and 3 patients, respectively. Among 29 patients with matched samples, mutational heterogeneity increased postprogression on PARPis, showing at least one postspecific mutation in 89.7% of the patients. These mutations indicate non-exclusive acquired resistance mechanisms—homologous recombination repair restoration (28%), replication fork stability (34%), upregulated survival pathway (41%), target loss (10%), and drug efflux (3%). We observed poor progression-free survival with subsequent chemotherapy in patients with homologous recombination repair restoration (P = 0.003) and those with the simultaneous involvement of two or more resistance mechanisms (P = 0.040). Conclusions: Analysis of serial ctDNAs highlighted multiple acquired resistance mechanisms, providing valuable insights for improving postprogression treatment and survival.

Ultra-deep sequencing to detect low-frequency mutations in circulating tumor-derived DNA (ctDNA) increases the diagnostic value of liquid biopsy. The demand for large ctDNA panels for comprehensive genomic profiling and tumor mutational burden (TMB) estimation is increasing; however, few ctDNA panels for TMB have been validated. Here, we designed a ctDNA panel with 531 genes, named TMB500, along with a technical and clinical validation. Synthetic reference cell-free DNA materials with predefined allele frequencies were sequenced in a total of 92 tests in 6 batches to evaluate the precision, linearity, and limit of detection of the assay. We used clinical samples from 50 patients with various cancers, 11 healthy individuals, and paired tissue samples. Molecular barcoding and data analysis were performed using customized pipelines. The assay showed high precision and linearity (coefficient of determination, r² =0.87) for all single nucleotide variants, with a limit of detection of 0.24%. In clinical samples, the TMB500 ctDNA assay detected most variants present and absent in tissues, showing that ctDNA could assess tumor heterogeneity in different tissues and metastasis sites. The estimated TMBs correlated well between tissue and blood, except in 4 cases with extreme heterogeneity that showed very high blood TMBs compared to tissue TMBs. A pilot evaluation showed that the TMB500 assay could be used for disease monitoring. The TMB500 assay is an accurate and reliable ctDNA assay for many clinical purposes. It may be useful for guiding the treatment of cancers with diverse genomic profiles, estimating TMB in immune therapy, and disease monitoring.

Hongkyung Kim, M.D., Ph.D., Jinho Lee, M.D., Mi Ri Park, B.S., Zisun Choi, M.S., Seung Jung Han, Ph.D., Dongha Kim, M.S., Saeam Shin, M.D., Ph.D., Seung-Tae Lee, M.D., Ph.D., Jong Rak Choi, M.D., Ph.D., and Seung Woo Park, M.D., Ph.D.. Ann Lab Med 2025;45:199-208. https://doi.org/10.3343/alm.2024.0345

Purpose: Cervical smear samples are easily obtainable and may effectively reflect the tumor microenvironment in gynecological cancers. Therefore, we investigated the feasibility of genomic profiling based on tumor DNA analysis from cervical smear samples from endometrial cancer patients.Materials and methods: Preoperative cervical smear samples were obtained via vaginal sampling in 50 patients, including 39 with endometrial cancer and 11 with benign uterine disease. Matched blood samples were obtained simultaneously. Genomic DNA (gDNA) from cervical smear and/or cell-free DNA from whole blood were extracted and sequenced using the Pan100 panel covering 100 endometrial cancer-related genes.Results: Cervical swab-based gDNA analysis detected cancer with 67% sensitivity and 100% specificity, showing a superior performance compared to that of the matched blood or Pap smear tests. Cervical swab-based gDNA effectively identified patients with loss of MSH2 or MSH6 and aberrant p53 expression based on immunohistochemistry. Genomic landscape analysis of cervical swab-based gDNA identified PTEN, PIK3CA, TP53, and ARID1A as the most frequently altered genes. Furthermore, 26 endometrial cancer patients could be classified according to the Proactive Molecular Risk Classifier for Endometrial Cancer.Conclusion: Cervical swab-based gDNA test showed an improved detection potential and allowed the classification of patients, which has both predictive and prognostic implications.

Purpose: Endometrial cancer is a common gynecologic malignancy that lacks effective noninvasive screening tools as traditional approaches rely on invasive biopsies. In this large prospective study, we evaluated a novel approach combining vaginal swab DNA and plasma-based ctDNA for genomic profiling to provide a comprehensive framework for diagnosis, prognosis, and disease monitoring. Experimental Design: Adult patients with diverse stages of endometrial cancer, preneoplastic disease, and benign endometrial conditions were prospectively recruited over 2 years. Paired vaginal swab DNA and plasma-based ctDNA were collected preoperatively, and additional plasma samples were obtained at multiple time points postoperatively. Deep next-generation sequencing targeting 101 genes was performed, achieving an average depth exceeding 40,000×. Results: A total of 191 patients contributed 388 samples. Vaginal swab DNA demonstrated 77.7% sensitivity and 96.6% specificity. PTEN mutations were associated with favorable prognosis (HR: 0.27; 95% confidence interval, 0.092–0.77), and TP53 mutations were associated with poor prognosis (HR: 3.7; 95% confidence interval, 1.4–10). A novel classification system based on the mutational profile of PTEN/TP53 identified distinct prognostic groups. Plasma-based ctDNA was significantly associated with stage, lymphovascular invasion, and prognosis (P < 0.01 for all). Patients with preoperative positive plasma-based ctDNA results exhibited poorer outcomes (P < 0.01), whereas postoperative positive ctDNA results enabled early detection of recurrence. Conclusions: These two noninvasive methods play distinct, complementary roles in the management of endometrial cancer. Vaginal swab DNA and novel PTEN/TP53-based classification have distinct prognostic advantages over existing frameworks. Plasma-based ctDNA provides dynamic insights into recurrence risk and disease progression.