Next-Generation Sequencing Panel Analysis of Clinically Relevant Mutations in Circulating Cell-Free DNA from Patients with Gestational Trophoblastic Neoplasia: A Pilot Study

Gestational trophoblastic neoplasia (GTN) originates from placental tissue and exhibits the potential for invasion and metastasis. Gene alterations in GTN have not been extensively studied because of a lack of qualified tumor specimens after chemotherapy. GTN has a rapid growth rate and is highly metastatic, which makes circulating tumor DNA (ctDNA) sequencing a promising modality for gene profiling. Accordingly, in this study, we performed targeted next-generation sequencing (NGS) of 559 tumor-associated genes using circulating cell-free DNA (cfDNA) collected prior to chemotherapy from 11 patients with GTN. All sequenced genes were associated with oncogenesis, progression, and targeted therapy. The average cfDNA level was 0.43 ± 0.22 ng/μL. Significant correlations were found between cfDNA concentration and maximum lesion diameter (r = 0.625, p=0.040) and time for human chorionic gonadotropin beta subunit (β-HCG) recovering to normal level (r = 0.609, p=0.047). There were no significant correlations between cfDNA concentrations and β-HCG expression level or lung metastasis. ctDNA mutations were detected in all patients, and 73 mutant genes were detected in 11 patients. BMPR1A (27.3%), LRP1B (27.3%), ERCC4 (18.2%), FGF14 (18.2%), HSP90AA1 (18.2%), KAT6A (18.2%), KMT2D (18.2%), MAP3K1 (18.2%), RANBP2 (18.2%), and ZNF217 (18.2%) mutations were detected as overlapping mutations. The mRNA and protein levels of bone morphogenetic protein receptor type 1A were significantly downregulated in human JAR and JEG-3 choriocarcinoma cells (p < 0.0001), whereas mRNA and protein levels of mitogen-activated protein kinase kinase kinase 1 were upregulated in these two cell lines (p=0.0128, p=0.0012, respectively). These genes may play important roles in GTN initiation and progression and may be candidate targets for GTN treatment. These findings suggested that cfDNA levels could provide potential assessment value in disease severity of GTN and that ctDNA sequencing was a promising approach for identifying gene mutations in GTN.