A Study of the eIF4E Pathway in CTCs Isolated From NSCLC And Prostate Cancer Patients Using ApoStream®

Clinical Application: Pharmacodynamic Analysis of an Antisense Drug Targeting eIF4E

Key Words: CTCs, eIF4E, head-to-head comparison, ApoStream®, protein expression, pharmacodynamics

Background: Eukaryotic initiation factor-4E (eIF-4E) is a protein that is involved in the translation of key growth and survival factors that contribute to tumor progression and the spread of cancer. It is upregulated in a number of different cancers, including breast, head and neck, prostate, lung, bladder, colon, thyroid and non-Hodgkins’ lymphomas. This trial examined the effects of an eIF-4E antisense drug in non-small cell lung (NSCLC) and castration resistant prostate cancer patients. ApoCell was contracted to  determine CTC counts and the biomarker expression levels of both eIF-4E and other downstream targets through the course of treatment.

Methods: Using prostate and NSCLC patient blood samples, ApoCell conducted a head-to-head comparison of two CTC isolation platforms – the CellSearch® Profile kit and our proprietary antibody-independent system, ApoStream®. Cells recovered from both systems were stained for DAPI, Cytokeratin (CK), and CD45, as well as multiple additional biomarkers – eIF-4E, cMyc, 4EBP1, p4EBP1, survivin, Bcl-2, and cyclin D1 – and were analyzed by Laser Scanning Cytometry. CTCs were identified as cells exhibiting a DAPI+/CK+/CD45- phenotype. Counts from the two platforms were compared and the ApoStream® system was incorporated into the trial to measure the expression of eIF-4E related biomarkers in CTCs.

Results:

Figure 1. Head-to-head Comparison Between ApoStream®
and CellSearch® Recovery Rates. CTC counts form the
CellSearch® and ApoStream® systems for prostate and NSCLC
patients. CTC counts obtained from ApoStream® were
significantly higher (p<0.05 for both cancer types) compared
to CellSearch®.
Figure 2. eIF-4E Expression Results in CTCs Enriched by ApoStream®. CTC count enriched by ApoStream® for all patients in the study was found to be positively correlated to the expression levels of eIF-4E. There was a trend toward a correlation between
eIF-4E levels and cyclin D1, survivin, and Bcl-2 levels (not shown). Overall, eIF-4E expression levels were observed to be higher in prostate cancer patients than NSCLC patients.

Impact: The ApoStream® platform demonstrated higher recovery of CTCs from the blood of prostate and NSCLC patients compared to the EpCAM-dependent CellSearch® platform. Protein analysis on cells captured by ApoStream® was shown to be feasible. Preliminary biomarker analysis indicates that this compound affects the eIF-4E pathway in CTCs from NSCLC and prostate cancer patients.

Reference: Wu W, et al. “Expression of eIF-4E Relevant Biomarkers Detected in Circulating Tumor Cells from Metastatic NSCLC
And Prostate Cancer Patients Using Antibody-Independent ApoStream® Technology.” ePub Abstract, ASC0 2012.