A recurrent novel MGA-NUTM1 fusion identifies a new subtype of high grade spindle cell sarcoma

NUTM1-rearranged tumors are defined by the presence of a gene fusion between NUTM1 and various gene partners, and typically follow a clinically aggressive disease course with poor outcomes despite conventional multi-modality therapy. NUTM1-rearranged tumors display histologic features of a poorly differentiated carcinoma with areas of focal squamous differentiation and typically express the NUTM1-BRD4 fusion gene defining a distinct clinico-pathologic entity – NUT carcinoma (NC). NC with mesenchymal differentiation have rarely been described in the literature. In this report, we describe the characterization of two cases of high grade spindle cell sarcoma harboring a novel MGA-NUTM1 fusion. Whole genome sequencing identified the presence of complex rearrangements resulting in a MGA-NUTM1 fusion gene in the absence of other significant somatic mutations. Genetic rearrangement was confirmed by fluorescence in situ hybridization, and expression of the fusion gene product was confirmed by transcriptomic analysis. The fusion protein was predicted to retain nearly the entire protein sequence of both MGA (exons 1-22) and NUTM1 (exons 3-8). Histopathologically, both cases were high grade spindle cell sarcomas without specific differentiation markers. In contrast to typical cases of NC, these cases were successfully treated with aggressive local control measures (surgery and radiation) and both patients remain alive without disease. These cases describe a new subtype of NUTM1-rearranged tumors warranting expansion of diagnostic testing to evaluate for the presence of MGA-NUTM1 or alternative NUTM1 gene fusions in the diagnostic workup of high grade spindle cell sarcomas or small round blue cell tumors of ambiguous lineage.

Cold Spring Harb Mol Case Stud. 2018 Dec 14. pii: mcs.a003194. doi: 10.1101/mcs.a003194.


Other Contributors

Diolaiti D1, Dela Cruz FS2, Gundem G1, Bouvier N1, Boulad M1, Zhang Y1, Chou AJ1, Dunkel IJ1, Sanghvi R3, Shah M3, Geiger H3, Rahman S3, Felice V3, Wrzeszczynski KO3, Darnell RB3, Antonescu CR1, French CA4, Papaemmanuil E1, Kung AL1, Shukla N1.


1 Memorial Sloan Kettering Cancer Center
2 Memorial Sloan Kettering Cancer Center
3 New York Genome Center
4 Brigham and Women’s Hospital/Harvard Medical School