Antigene MYCN Silencing by BGA002 Inhibits SCLC Progression Blocking mTOR Pathway and Overcomes Multidrug Resistance

SIMPLE SUMMARY: Small-cell lung cancer (SCLC) is the most aggressive form of lung cancer, is mostly associated with smoking and has a low survival rate. Among the different alterations in genes identified in SCLC, those related to the MYC family have emerged as highly relevant, alterations MYCN particularly define an aggressive and immunotherapy resistant SCLC subgroup. Due to its highly restricted expression in normal cells, MYCN is an ideal target for precision medicine, though it is difficult to target with traditional approaches. We propose an innovative approach to target MYCN in SCLC by an MYCN-specific expression inhibition at the level of gene transcription through an antigene oligonucleotide (BGA002). BGA002 exerted a potent and specific MYCN silencing in MYCN-expressing SCLC, leading to reversion of specific pathways and induction of cell death. Moreover, systemic administration of BGA002 inhibited tumor progression and significantly increased survival in SCLC mouse models, while also overcoming multidrug resistance. ABSTRACT: Small-cell lung cancer (SCLC) is the most aggressive lung cancer type, and is associated with smoking, low survival rate due to high vascularization, metastasis and drug resistance. Alterations in MYC family members are biomarkers of poor prognosis for a large number of SCLC. In particular, MYCN alterations define SCLC cases with immunotherapy failure. MYCN has a highly restricted pattern of expression in normal cells and is an ideal target for cancer therapy but is undruggable by traditional approaches. We propose an innovative approach to MYCN inhibition by an MYCN-specific antigene—PNA oligonucleotide (BGA002)—as a new precision medicine for MYCN-related SCLC. We found that BGA002 profoundly and specifically inhibited MYCN expression in SCLC cells, leading to cell-growth inhibition and apoptosis, while also overcoming multidrug resistance. These effects are driven by mTOR pathway block in concomitance with autophagy reactivation, thus avoiding the side effects of targeting mTOR in healthy cells. Moreover, we identified an MYCN-related SCLC gene signature comprehending CNTFR, DLX5 and TNFAIP3, that was reverted by BGA002. Finally, systemic treatment with BGA002 significantly increased survival in MYCN-amplified SCLC mouse models, including in a multidrug-resistant model in which tumor vascularization was also eliminated. These findings warrant the clinical testing of BGA002 in MYCN-related SCLC.