Abstract 4662: Beta blockers abrogate EGFR TKI resistance induced by adrenergic receptor-mediated upregulation of IL-6 and modulation of the LKB1/AMPK/mTOR axis
Authors: Nilsson Monique B. , Sun Huiying , Diao Lixia , Tong Pan , Fan Youhong , Tran Hai , Liu Diane , Armaiz Pena Guillermo , Wang Jing , Rowe Phil , Webster Alan , Lee Jack , Gomez Daniel , Hong Waun Ki , Wistuba Ignacio , Sood Anil , Heymach John 
Published: July 2016

Abstract
Therapeutic strategies to target EGFR tyrosine kinase inhibitor (TKI) resistance mediated by mechanisms other than T790M are a major clinical challenge. Studies have implicated IL-6 as a mediator of EGFR TKI resistance, and IL-6 is known to be regulated by adrenergic receptors (AR) in some cancers. We investigated whether adrenergic pathways can promote T790M-independent EGFR TKI resistance in preclinical models and in clinical studies. We found that β2-AR was highly expressed in our panel of 119 cell lines and in NSCLC clinical specimens. Activation of β-ARs by stress hormones such as norepinephrine (NE) induced a dramatic rise in IL-6, and this occurred through β2-ARs. β-AR inhibitors (i.e. propranolol), but not α-AR inhibitors, blocked IL-6 induction. Analysis of downstream signaling pathways revealed that β2-ARs induced IL-6 expression through activation of adenylyl cyclase, p90RSK and CREB. To identify novel signaling pathways modulated by ARs, we stimulated NSCLC cell lines with NE and analyzed protein lysates by RPPA to detect expression and activation of &gt;100 proteins. β-AR signaling inactivated the tumor suppressor LKB1 through phosphorylation of S428 and subsequently increased mTOR activity. LKB1 inactivation was critical for IL-6 induction. This finding is important as LKB1 loss is known to be a driver of NSCLC resistance and metastasis. Moreover, we found that β2-AR activation promoted EGFR TKI resistance in cell lines and in mouse models of EGFR mutant NSCLC. The effect of β-AR on EGFR TKI resistance was blocked by the addition of the beta blocker propranolol or IL-6 antibodies, in vitro and in vivo. Consistent with our preclinical studies, in the phase III ZEST clinical study testing erlotinib vs vandetanib, we found that high plasma levels of IL-6 was associated with a worse PFS and OS in the erlotinib arm. In addition, we found that circulating levels of IL-6 were significantly lower in NSCLC patients incidentally receiving beta blockers in the BATTLE trial. Finally, we analyzed the influence of incidental beta blocker use in the LUX-Lung3 study testing afatinib vs chemotherapy in EGFR mutant NSCLC patients. In patients not receiving beta blockers, the median PFS was 11.1 and 6.9 months for afatinib and chemotherapy, respectively, and afatinib improved PFS with a hazard ratio (HR) of 0.60. In patients receiving beta blockers, the median PFS was 13.6 and 2.5 for afatinib and chemotherapy, respectively, and afatinib improved PFS with a HR of 0.25. In conclusion, our preclinical and clinical data provide evidence that β2-AR activation can upregulate IL-6 in EGFR mutant+ NSCLC, modulate the LKB1/AMPK/mTOR axis, and promote EGFR TKI resistance. Moreover, EGFR mutant+ patients using beta blockers had greater relative PFS benefit from afatinib vs chemotherapy compared with those not using beta blockers, supporting future clinical testing of EGFR TKIs in combination with beta blockers.
Citation Format: Monique B. Nilsson, Huiying Sun, Lixia Diao, Pan Tong, Youhong Fan, Hai Tran, Diane Liu, Guillermo Armaiz Pena, Jing Wang, Phil Rowe, Alan Webster, Jack Lee, Daniel Gomez, Waun Ki Hong, Ignacio Wistuba, Anil Sood, John Heymach. Beta blockers abrogate EGFR TKI resistance induced by adrenergic receptor-mediated upregulation of IL-6 and modulation of the LKB1/AMPK/mTOR axis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4662.