TP53 Alterations Are Associated With Poor Survival in Patients With Primary Mediastinal Nonseminoma Germ Cell Tumors

Germ cell tumors (GCT) are divided into 2 groups: seminoma and nonseminoma, with primary mediastinal nonseminoma GCT having the most aggressive clinical behavior. This article describes the genomic landscape of primary mediastinal GCTs and whether selected genomic alterations are associated with poor prognosis.Background Primary mediastinal nonseminoma germ cell tumors (PMNSGCT) are a subgroup of nonseminoma germ cell tumors (GCT) with poor prognosis. In this study, PMNSGCT-specific genomic landscape was analyzed and correlated with clinical outcomes. Methods DNA was extracted and sequenced from 28 archival tumor tissue of patients with mediastinal GCT (3 seminoma and 25 nonseminoma). Overall survival (OS) and association with gene alterations were estimated using the Kaplan-Meier and univariate Cox regression methods. Results Three patients (11%) had a karyotype XXY, 17/28 (61%) tumor samples presented chromosome 12p amplification. Somatic mutations were detected in 19/28 (68%) samples. The most frequently mutated genes were: TP53 (13/28; 46%), KIT (5/28; 18%), and KRAS (5/28; 18%). Deleterious TP53 alterations were associated with significantly reduced overall survival (HR: 7.16; P = .012). Conclusions TP53 alterations are common in PMNSGCT and are associated with reduced overall survival, potentially underlying the poor sensitivity to chemotherapy observed in these patients.