Abstract 764: Rational combination of PF-06463922 (next-generation ALK inhibitor) with PI3K pathway inhibitors overcomes ALKi resistance in EML4-ALK+ NSCLC models
Authors: Wei Ping , Qiu Ming , Lee Nathan , Cao Joan , Wang Hui , Tsaparikos Konstantinos , Fan Conglin , Sargis Timothy , Lam Justine , Lira Maruja E. , Lui Goldie , Hardwick James , Fantin Valeria , Rejto Paul , Smeal Tod 
Published: August 2015

Abstract
Crizotinib (PF-02341066) is a small molecule tyrosine kinase inhibitor of ALK, ROS1 and c-MET that is approved in over 70 countries for the treatment of ALK fusion positive non-small cell lung cancer (ALK+ NSCLC). Crizotinib achieved robust objective response rates of approximately 60% in ALK+ NSCLC and significantly improved progression free survival compared to chemotherapy. The emergence of secondary mutations within the ALK kinase domain or the activation of compensatory signaling pathways in crizotinib and other ALKi refractory tumors prompted searches for next generation of ALKi active against resistance mutations as single agents or in combination with other treatments. Such effort led to our recent discovery of PF-06463922, an ALK/ROS1 inhibitor with greatly improved ALK potency, brain penetration, and broad spectrum activity against all known clinical ALKi-resistant mutations. PF-06463922 is being tested in a Phase I clinical trial in both ALK+ and ROS1 fusion positive NSCLC in treatment naive or ALKi relapsed patients.
In our current preclinical study, we explored rational combination strategies to further improve the efficacy of PF-06463922 in ALKi resistant cells or tumors. Our results show that compared to PF-06463922 alone, the combination of this compound with PI3K pathway inhibitors, such as PF-05212384 (PI3K/mTOR), GDC0941 (pan-PI3K) or GDC0032 (beta-sparing) leads to more robust anti-proliferative activity in vitro and greater duration of efficacy in vivo in the ALKi resistant models. These PI3K pathway inhibitors also partially overcome EGF or HGF ligand-induced resistance to PF-06463922. Interestingly, in addition to AKT signaling, both compounds inhibit ERK signaling as well, which may be essential for their enhancement of PF-06463922 cell activity or tumor efficacy in combination settings. Studies are ongoing to identify optimal partners for PF-06463922 combination using isoform selective PI3Ki, AKTi and mTORi. We are also exploring the breadth of efficacy of this combination in overcoming resistance to crizotinib, PF-06463922 or other ALKi. The findings provide important evidence that will help define the clinical development path for PF-06463922. This research effort may ultimately lead to more effective approaches to treat ALKi refractory patients in the clinic.
Citation Format: Ping Wei, Ming Qiu, Nathan Lee, Joan Cao, Hui Wang, Konstantinos Tsaparikos, Conglin Fan, Timothy Sargis, Justine Lam, Maruja E. Lira, Goldie Lui, James Hardwick, Valeria Fantin, Paul Rejto, Tod Smeal. Rational combination of PF-06463922 (next-generation ALK inhibitor) with PI3K pathway inhibitors overcomes ALKi resistance in EML4-ALK+ NSCLC models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 764. doi:10.1158/1538-7445.AM2015-764