Matthew R. Guthrie

PURPOSE: Small-cell lung cancer (SCLC) has been treated clinically as a homogeneous disease, but recent discoveries suggest that SCLC is heterogeneous. Whether metabolic differences exist among SCLC subtypes is largely unexplored. In this study, we aimed to determine whether metabolic vulnerabilities exist between SCLC subtypes that can be therapeutically exploited. EXPERIMENTAL DESIGN: We performed steady state metabolomics on tumors isolated from distinct genetically engineered mouse models (GEMM) representing the MYC- and MYCL-driven subtypes of SCLC. Using genetic and pharmacologic approaches, we validated our findings in chemo-naïve and -resistant human SCLC cell lines, multiple GEMMs, four human cell line xenografts, and four newly derived PDX models. RESULTS: We discover that SCLC subtypes driven by different MYC family members have distinct metabolic profiles. MYC-driven SCLC preferentially depends on arginine-regulated pathways including polyamine biosynthesis and mTOR pathway activation. Chemo-resistant SCLC cells exhibit increased MYC expression and similar metabolic liabilities as chemo-naïve MYC-driven cells. Arginine depletion with pegylated arginine deiminase (ADI-PEG 20) dramatically suppresses tumor growth and promotes survival of mice specifically with MYC-driven tumors, including in GEMMs, human cell line xenografts, and a patient-derived xenograft from a relapsed patient. Finally, ADI-PEG 20 is significantly more effective than the standard-of-care chemotherapy. CONCLUSIONS: These data identify metabolic heterogeneity within SCLC and suggest arginine deprivation as a subtype-specific therapeutic vulnerability for MYC-driven SCLC.

// Robert J. Cardnell 1 , Lerong Li 2 , Triparna Sen 1 , Rasha Bara 1 , Pan Tong 2 , Junya Fujimoto 3 , Abbie S. Ireland 4 , Matthew R. Guthrie 4 , Sheila Bheddah 5 , Upasana Banerjee 1 , Nene N. Kalu 1 , You-Hong Fan 1 , Scott J. Dylla 5 , Faye M. Johnson 1,6 , Ignacio I. Wistuba 3 , Trudy G. Oliver 4 , John V. Heymach 1 , Bonnie S. Glisson 1 , Jing Wang 2,4,* and Lauren A. Byers 1,6,* 1 Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA 2 Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA 3 Department of Molecular Translational Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA 4 Department of Oncological Sciences, University of Utah, Huntsman Cancer Institute, Salt Lake City, UT, USA 5 AbbVie StemCentrx, LLC, San Franciso, CA, USA 6 The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA * Co-senior authors Correspondence to: Lauren A. Byers, email: // Keywords : Alisertib, DLL3, rovalpituzumab tesirine, SCLC, TTF1 Received : July 04, 2017 Accepted : August 14, 2017 Published : September 01, 2017 Abstract Small cell lung cancer (SCLC) is a recalcitrant cancer for which no new treatments have been approved in over 30 years. While molecular subtyping now guides treatment selection for patients with non-small cell lung cancer and other cancers, SCLC is still treated as a single disease entity. Using model-based clustering, we found two major proteomic subtypes of SCLC characterized by either high thyroid transcription factor-1 (TTF1)/low cMYC protein expression or high cMYC/low TTF1. Applying “drug target constellation” (DTECT) mapping, we further show that protein levels of TTF1 and cMYC predict response to targeted therapies including aurora kinase, Bcl2, and HSP90 inhibitors. Levels of TTF1 and DLL3 were also highly correlated in preclinical models and patient tumors. TTF1 (used in the diagnosis lung cancer) could therefore be used as a surrogate of DLL3 expression to identify patients who may respond to the DLL3 antibody-drug conjugate rovalpituzumab tesirine. These findings suggest that TTF1, cMYC or other protein markers identified here could be used to identify subgroups of SCLC patients who may respond preferentially to several emerging targeted therapies.

Small cell lung cancer (SCLC) is one of the most deadly cancers and currently lacks effective targeted treatment options. Recent advances in the molecular characterization of SCLC has provided novel insight into the biology of this disease and raises hope for a paradigm shift in the treatment of SCLC. We and others have identified activation of MYC as a driver of susceptibility to Aurora kinase inhibition in SCLC cells and tumors that translates into a therapeutic option for the targeted treatment of MYC-driven SCLC. While MYC shares major features with its paralogs MYCN and MYCL, the sensitivity to Aurora kinase inhibitors is unique for MYC-driven SCLC. In this review, we will compare the distinct molecular features of the 3 MYC family members and address the potential implications for targeted therapy of SCLC.