Expanding the Molecular Taxonomy of NUT Midline Carcinomas With Multiomic Analyses

ASCO Annual Meeting 2021 Abstract
Authors Henry G. Kaplan, Alex Barrett, Jiaxin Niu, Somasundaram Subramaniam, Maria Matsangou

Background: NUT midline carcinoma (NMC) is an aggressive squamous cell carcinoma molecularly defined by a chromosomal rearrangement of nuclear protein in testis (NUTM1) with bromodomain-containing protein 3 or 4 (BRD3/4). While NMCs are characterized by this rare canonical gene rearrangement little is known about the transcriptome and proteosome of this rare disease. As such, we set out to comprehensively characterize five NMC cases in which we attained targeted DNA sequencing, full-transcriptome RNA sequencing, and targeted proteomics. We further examine and integrate these results in order to better understand the relationship between gene expression and protein abundance within the context of NMC.

Methods: All cases were analyzed for genomic and transcriptomic alterations against a custom panel via the Tempus xT tissue biopsy assay (DNA sequencing of 648 genes in tumor and matched normal samples at 500x depth and full-transcriptome RNA sequencing) for germline and/or somatic mutations. The xT assay detects single nucleotide variants, specific insertion/deletions, amplifications and gene fusions, as well as tumor mutational burden (TMB) and microsatellite instability (MSI) status. Proteomic data were obtained utilizing digital spatial profiling through Nanostring immune, MAPK and PI3/AKT, and pan tumor nCounter GeoMix panels.

Results: Clinical characteristics, histology, and genomic/proteomic alterations for 5 NMC cases are presented. Cases were defined by pathological assessment and the identification of the canonical NUTM1 fusion, further broken down by fusion partner with three patients having NUTM1-BRD4 fusions, one NUT-BRD3, and one NUT-ZMYND8. TMBs ranged for 0.8-.6 mutations/megabases (n=5). All patients were MSI stable (5/5). Of three patients with available PD-L1 IHC result, one had elevated PD-L1 tumor staining at 70%. Results will be presented from full-transcriptome RNA expression analysis indicating overexpression of BRAF, MYC, mTOR, and EGFR, among others. Targeted proteomics were performed to assess relative abundance at the protein level (results to be presented). Clinical follow up for the five patients revealed that two have survived beyond 7 months. A lung primary patient treated with surgical resection and post op radiation (XRT) is NED at 63 months. A sinus primary patient is NED at 16 months after a partial response (PR) to taxotere/5FU/Cisplatin followed by resection and XRT/cis platin. One patient had a brief PR from ifosphamide/etoposide/vorinostat. One patient’s tumor grew through XRT/cisplatin.

Conclusions: Multi-omic analysis has the potential to further elucidate the mechanisms of tumor growth in NMC and identify new targets for the treatment of this aggressive and poor prognosis disease.