MYCN gene amplification

MYCN amplification is detected in 16% to 25% of neuroblastoma tumors.[18] Among patients with high-risk neuroblastoma, 40% to 50% of cases show MYCN amplification.[19]

In all stages of disease, amplification of the MYCN gene strongly predicts a poorer prognosis, in both time to tumor progression and OS, in almost all multivariate regression analyses of prognostic factors.[1,2] In the ANBL00B1 (NCT00904241) study of 4,832 newly diagnosed patients enrolled between 2007 to 2017, the 5-year EFS and OS rates were 77% and 87%, respectively, for patients whose tumors were MYCN nonamplified (n = 3,647; 81%). In comparison, the 5-year EFS and OS rates were 51% and 57%, respectively, for patients whose tumors were MYCN amplified (n = 827; 19%).[9]

Within the localized-tumor MYCN-amplified cohort, patients with hyperdiploid tumors have better outcomes than patients with diploid tumors.[20] However, patients with hyperdiploid tumors with MYCN amplification or any SCAs do relatively poorly, compared with patients with hyperdiploid tumors without MYCN amplification.[3]

Most unfavorable clinical and pathobiological features are associated, to some degree, with MYCN amplification. In a multivariable logistic regression analysis of 7,102 patients in the International Neuroblastoma Risk Group (INRG) study, pooled SCAs and gains of 17q were poor prognostic features, even when not associated with MYCN amplification. However, another poor prognostic feature, SCAs at 11q, are almost entirely mutually exclusive of MYCN amplification.[21,22]

In a cohort of 6,223 patients from the INRG database with known MYCN status, the OS hazard ratio (HR) associated with MYCN amplification was 6.3 (95% confidence interval [CI], 5.7–7.0; P < .001). The greatest adverse prognostic impact of MYCN amplification for OS was in the youngest patients (aged <18 months: HR, 19.6; aged ≥18 months: HR, 3.0). Patients whose outcome was most impacted by MYCN status were those with otherwise favorable features, including age younger than 18 months, high mitosis-karyorrhexis index, and low ferritin.[23][Level of evidence C1]

Intratumoral heterogeneous MYCN amplification (hetMNA) refers to the coexistence of MYCN-amplified cells (as a cluster or as single scattered cells) and non–MYCN-amplified tumor cells. HetMNA has been reported infrequently. It can occur spatially within the tumor as well as between the tumor and the metastasis at the same time or temporally during the disease course. The International Society of Paediatric Oncology Europe Neuroblastoma (SIOPEN) biology group investigated the prognostic significance of this neuroblastoma subtype. Tumor tissue from 99 patients identified as having hetMNA and diagnosed between 1991 and 2015 was analyzed to elucidate the prognostic significance of MYCN-amplified clones in otherwise non-MYCN–amplified neuroblastomas. Patients younger than 18 months showed a better outcome in all stages compared with older patients. The genomic background correlated significantly with relapse frequency and OS. No relapses occurred in cases of only numerical chromosomal aberrations. This study suggests that hetMNA tumors be evaluated in the context of the genomic tumor background in combination with the clinical pattern, including the patient's age and disease stage. Future studies are needed in patients younger than 18 months who have localized disease with hetMNA.[24]