Small cells - big issues: biological implications and preclinical advancements in small cell lung cancer.

Current treatment guidelines refer to small cell lung cancer (SCLC), one of the deadliest human malignancies, as a homogeneous disease. Accordingly, SCLC therapy comprises chemoradiation with or without immunotherapy. Meanwhile, recent studies have made significant advances in subclassifying SCLC based on the elevated expression of the transcription factors ASCL1, NEUROD1, and POU2F3, as well as on certain inflammatory characteristics. The role of the transcription regulator YAP1 in defining a unique SCLC subset remains to be established. Although preclinical analyses have described numerous subtype-specific characteristics and vulnerabilities, the so far non-existing clinical subtype distinction may be a contributor to negative clinical trial outcomes. This comprehensive review aims to provide a framework for the development of novel personalized therapeutic approaches by compiling the most recent discoveries achieved by preclinical SCLC research. We highlight the challenges faced due to limited access to patient material as well as the advances accomplished by implementing state-of-the-art models and methodologies.

C-Myc protein expression indicates unfavorable clinical outcome in surgically resected small cell lung cancer.

BACKGROUND: By being highly involved in the tumor evolution and disease progression of small cell lung cancer (SCLC), Myc family members (C-Myc, L-Myc, and N-Myc) might represent promising targetable molecules. Our aim was to investigate the expression pattern and prognostic relevance of these oncogenic proteins in an international cohort of surgically resected SCLC tumors. METHODS: Clinicopathological data and surgically resected tissue specimens from 104 SCLC patients were collected from two collaborating European institutes. Tissue sections were stained by immunohistochemistry (IHC) for all three Myc family members and the recently introduced SCLC molecular subtype-markers (ASCL1, NEUROD1, POU2F3, and YAP1). RESULTS: IHC analysis showed C-Myc, L-Myc, and N-Myc positivity in 48%, 63%, and 9% of the specimens, respectively. N-Myc positivity significantly correlated with the POU2F3-defined molecular subtype (r = 0.6913, p = 0.0056). SCLC patients with C-Myc positive tumors exhibited significantly worse overall survival (OS) (20 vs. 44 months compared to those with C-Myc negative tumors, p = 0.0176). Ultimately, in a multivariate risk model adjusted for clinicopathological and treatment confounders, positive C-Myc expression was confirmed as an independent prognosticator of impaired OS (HR 1.811, CI 95% 1.054-3.113, p = 0.032). CONCLUSIONS: Our study provides insights into the clinical aspects of Myc family members in surgically resected SCLC tumors. Notably, besides showing that positivity of Myc family members varies across the patients, we also reveal that C-Myc protein expression independently correlates with worse survival outcomes. Further studies are warranted to investigate the role of Myc family members as potential prognostic and predictive markers in this hard-to-treat disease.

Entinostat Enhances the Efficacy of Chemotherapy in Small Cell Lung Cancer Through S-phase Arrest and Decreased Base Excision Repair.

PURPOSE: Acquired chemoresistance is a frequent event in small cell lung cancer (SCLC), one of the deadliest human malignancies. Histone deacetylase inhibitors (HDACi) have been shown to synergize with different chemotherapeutic agents including cisplatin. Accordingly, we aimed to investigate the dual targeting of HDAC inhibition and chemotherapy in SCLC. EXPERIMENTAL DESIGN: The efficacy of HDACi and chemotherapy in SCLC was investigated both in vitro and in vivo. Synergistic drug interactions were calculated based on the HSA model (Combenefit software). Results from the proteomic analysis were confirmed via ICP-MS, cell-cycle analysis, and comet assays. RESULTS: Single entinostat- or chemotherapy significantly reduced cell viability in human neuroendocrine SCLC cells. The combination of entinostat with either cisplatin, carboplatin, irinotecan, epirubicin, or etoposide led to strong synergy in a subset of resistant SCLC cells. Combination treatment with entinostat and cisplatin significantly decreased tumor growth in vivo. Proteomic analysis comparing the groups of SCLC cell lines with synergistic and additive response patterns indicated alterations in cell-cycle regulation and DNA damage repair. Cell-cycle analysis revealed that cells exhibiting synergistic drug responses displayed a shift from G1 to S-phase compared with cells showing additive features upon dual treatment. Comet assays demonstrated more DNA damage and decreased base excision repair in SCLC cells more responsive to combination therapy. CONCLUSIONS: In this study, we decipher the molecular processes behind synergistic interactions between chemotherapy and HDAC inhibition. Moreover, we report novel mechanisms to overcome drug resistance in SCLC, which may be relevant to increasing therapeutic success.

Unfolding the secrets of small cell lung cancer progression: Novel approaches and insights through rapid autopsies.

The understanding of small cell lung cancer (SCLC) biology has increased dramatically in recent years, but the processes that allow SCLC to progress rapidly remain poorly understood. Here, we advocate the integration of rapid autopsies and preclinical models into SCLC research as a comprehensive strategy with the potential to revolutionize current treatment paradigms.