Abstract 3525: Functional analysis of epidermal growth factor receptor tyrosine kinase inhibitors: A comparison of Afatanib, Lapatinib, and Gefitinib in human tumor primary cultures.

Abstract

Abstract Introduction: Targeting epidermal growth factor receptor (EGFr) tyrosine kinases has provided effective therapies for NSCLC, breast & GI cancers. However, secondary mutations can confer resistance. New multi-targeted and/or irreversible inhibitors (TKI's) may overcome these mechanisms. We used the ex vivo analysis of programmed death (EVA/PCD) to compare the activity of the irreversible EGFr TKI, BIBW 2992 (Afatanib) with Gefitinib and Lapatinib and examined downstream signals with inhibitors of MEK/ERK & PI3K/mTOR. Methods: Human tumor 1° culture microspheroids isolated from 54 individual-patient specimens obtained at surgery or aspiration were examined for EGFr-TKI induced programmed cell death, using morphologic & metabolic endpoints as previously described (Nagourney R, Curr. Treat Opt in Oncol., 2006). Lethal concentration 50% (LC50’s) interpolated from 5-point dose response curves were compared and drug correlations were conducted by Pearson-Moment. Results: BIBW activity favored upper GI, NSCLC and ovary over breast and colorectal cancer. In NSCLC, EGFr mutation (+) tumors were significantly more sensitive than wild type to BIBW (P < .05). Patients relapsing after Erlotinib who carried T790M mutations remained BIBW sensitive despite Gefitinib resistance. BIBW activity correlated with Gefitinib (r = 0.35, P= 0.05) and the MEK/ERK inhibitor AZD 6244 (r = 0.43, P < 0.05) and trended to correlation with Lapatinib, but did correlate with mTOR or mTOR/PI3K inhibitors, Everolimus & BEZ235. Of 3 patients treated with Afatanib, 2 of 3 showed benefit, 1 durable SD & 1 durable PR. Conclusions: BIBW reveals activity in several tumor types including NSCLC, GI and ovary. In NSCLC LC50’s significantly favor EGFr mutation (+) ‘s with favorable results in T790M(+) patients. Correlations with AZD 6244 but not Everolimus or BEZ235, suggest MEK/ERK pathway to be the operative survival signal. EVA/PCD analysis in human tumor 1°cultures offers a platform to study novel strategies for EGFr-targeted therapies. Supported by the Vanguard Cancer Foundation & the Nagourney Institute. Citation Format: Robert Alan Nagourney, Paula J. Bernard, Eric Federico, Sophie Nguyen, Steven S. Evans. Functional analysis of epidermal growth factor receptor tyrosine kinase inhibitors: A comparison of Afatanib, Lapatinib, and Gefitinib in human tumor primary cultures. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3525. doi:10.1158/1538-7445.AM2013-3525