DLK1 distinguishes subsets of NF1-associated malignant peripheral nerve sheath tumors with divergent molecular signatures.

Purpose: MPNST is the leading cause of premature death among individuals with NF1 and the transcriptional aberrations that precede malignant transformation and contribute to MPNST tumorigenesis remain poorly defined. Alterations involving CDKN2A and components of PRC2 have been implicated as early drivers of PNST evolution, but these events do not occur in all MPNST. Accordingly, emerging data has begun to highlight the importance of molecular-based stratification to improve outcomes in patients with NF1-PNST.

Experimental Design: Here we perform an integrated analysis of multiple, independent datasets obtained from human NF1 patients to gain critical insight into PNST evolution and MPNST heterogeneity.

Results: We show that DLK1 is significantly increased in MPNST and provide evidence that DLK1 overexpression may precede histological changes consistent with malignancy. In complementary analyses, we find that serum levels of DLK1 are significantly higher in both mice and humans harboring MPNST compared to those without malignancy. Importantly, while DLK1 expression is increased in MPNST overall, through the integration of multiple, independent datasets we demonstrate that divergent levels of DLK1 expression distinguish MPNST subsets characterized by unique molecular programs and potential therapeutic vulnerabilities. Specifically, we show that overexpression of DLK1 is associated with the reactivation of embryonic signatures, an immunosuppressive microenvironment and a worse overall survival in patients with NF1-MPNST.

Conclusions: Collectively, our findings provide critical insight into MPNST tumorigenesis and support prospective studies evaluating the utility of DLK1 tissue and serum levels in augmenting diagnosis, risk assessment and therapeutic stratification in the setting of NF1-PNST.