An examination of crizotinib activity in human tumor primary culture micro-spheroids isolated from patients with advanced non-small cell lung cancer.

Abstract

e13558 Background: The amino-pyridine, Crizotinib (Criz) (PF02341066, Xalkori), active against c-MET is an inhibitor of anaplastic lymphoma kinase (ALK). Identification of ALK-gene rearrangement in NSCLC led to clinical trials & FDA approval. Recognition of ROS-1 mutations as Criz targets provided additional therapy options. ALK mutations found in NSCLC also occur in lymphoma, neuro & myofibroblastic tumors but may participate in the oncogenesis of other tumors. Methods: We used ex vivo analysis of programmed cell death (EVA/PCD) (Nagourney, R. Curr Treat. Op Oncol, 2006) to examine Criz activity in human tumor 1°culture micro-spheroids, from 60 surgical specimens, with a focus on NSCLC. Using metabolic (ATP-content; mitochondrial) & morphologic (membrane integrity) endpoints, dose response curves were interpolated to LC50 values for comparison of activity by patient & tumor type. Patients were screened for ALK & ROS-1 by FISH. Results: ALK (+) tumors reveal lower LC50’s (3.4 uM) vs. ROS-1 (+) (11.5 uM), despite clinical responses in both groups. A Criz-responding patient, at 2nd biopsy for progression, reverted to Criz-resistance but developed collateral sensitivity to cytotoxics that provided durable response. Despite FISH (-), a 39 y/o nonsmoker male, revealed exquisite sensitivity to Criz by repeat EVA/PCD. At our insistence, FISH conducted at a 2nd reference lab correctly identified ALK(+) qualifying for Criz, to which he responded, now at year 2. Using low LC50 as a phenotypicmarker of Criz responsiveness, we identified activity in an extremely rare pediatric sarcoma patient. When, secondarily screened, patient found ALK (+), followed by rapid objective response to Criz. Conclusions: Primary culture analyses provide insights into Criz activity including ALK (+) vs. ROS-1(+), individual patient response profiles, and the identification of Criz candidates, who might otherwise not be screened for sensitizing mutations. By capturing human tumors in their “native” state EVA/PCD offers opportunities to study Criz for unrecognized targets and analyze novel strategies including synergy & sequence dependence, less readily examined with genomic platforms.