Abstract C152: 4-Demethyl-4-cholesteryloxycarbonylpenclomedine (DM-CHOC-PEN) as a cytotoxic L-glutamine agonist in non-small cell lung cancer (NSCLC) involving the CNS

Abstract

Abstract Purpose: 4-Demethyl-4-cholesteryloxycarbonylpenclomedine (DM-CHOC-PEN) is a poly-chlorinated pyridine cholesteryl carbonate whose MOA is via bis-alkylation of DNA @ N7 - guanine and N6 - cytosine. DM-CHOC-PEN has undergone a Phase I study (allowed enrollment of subjects with advanced cancer +/- CNS involvement) and is being evaluated in a Phase II trial in subjects with advanced cancer involving the brain. Impressive objective responses and improved PFS/overall survival have been observed in subjects with NSCLC involving the CNS. The main aims of this presentation are to document a mechanism for DM-CHOC-PEN's penetration into NSCLC metastases involving the CNS via L-glutamine (GLM) transport. Methods: Human cancer cell lines [NSCLC - H2087 & H460 and SCLC - SHP-77 & H1417 - obtained from ATCC] were maintained in culture with complete RPMI (5% FBS, pen/strep/Amp. B), supplemented w/ L-glutamine [300 mg/500 mL medium, Sigma] @ 37oC and in moist 5% CO2 conditions. DM-CHOC-PEN was dissolved in tetrahydrofuran, impregnated into ChemoChads® that deliver drug 0.25 - 5 μg/mL in culture. Cells were grown in culture w/wo supplemental GLM for 36 h and then ChemoChads were added. Cytotoxicity was conducted in multi-well plates using the Cytotec® Assay and measuring IC50 values after 24 hr. All assays were conducted in triplicate. Results: All 4-cell lines grew well in complete RPMI supplemented with L-glutamine. Both SCLC cell lines grew well as clumps of small single cells in suspension, +/- GLM suppl. but were not sensitive to DM-CHOC-PEN, w/ or wo/ GLM supplements. In contrast, both NSCLC cell lines grew as coalescing islands of adhered well-differentiated cells in GLM supplemented medium, but did not grow well in GLM-free medium. Of interest, both NSCLC cell lines were sensitive to DM-CHOC-PEN (IC50 0.25-0.75 μg/mL) w/ GLM-suppl. medium, but were not sensitive (IC50 >5 μg/mL) in GLM-free medium. However, when GLM was added to the GLM-free medium w/ DM-CHOC-PEN, the cells resumed sensitivity to the drug. Similar findings have been observed for 6/7-human NSCLC explants obtained from CNS surgical samples (which will be discussed). Conclusion: The common structural similarities between DM-CHOC-PEN, GLM and Ɣ-aminobutyric acid (GABA) could allow the sharing of a transport/receptor mechanism into the cerebellum and other CNS safe havens that provide a favorable microenvironment for NSCLC cells to colonize, thrive and grow. The drug when administered IV associates with erythrocytes (∼50%), which facilitates its entry into the neoplastic cerebral circulation and now support for its transport into metastatic NSCLC involving the CNS via the GLM transport system is presented. In the absence of GLM, the GLM-transport system shuts down. Of clinical interest is that all subjects with cerebellar NSCLC lesions have responded to DM-CHOC-PEN in the clinical trials with objective responses, improved PFS (6-17+ months) and improved QOL (AACR, Abst. 1161, 2015). The cerebellum offers a unique microenvironment rich in chemical transmitters and amino acids - in particular GLM and Ɣ-aminobutyric acid (GABA). Supported by NCI/SBIR grant - R43/44CA132257. Citation Format: Lee Roy Morgan, Jr., Ed Benes, Andrew H. Rodgers, Tallat Mahmood, Roy S. Weiner, Marcus L. Ware. 4-Demethyl-4-cholesteryloxycarbonylpenclomedine (DM-CHOC-PEN) as a cytotoxic L-glutamine agonist in non-small cell lung cancer (NSCLC) involving the CNS. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C152.