P2.01-088 Prenylation Inhibitors in Lung Adenocarcinoma: Comparison of Zoledronic Acid and a Novel Lipophilic Bisphosphonate

Abstract

The prenylation inhibitor zoledronic acid is a standard-of-care therapeutic option in bone metastasis. Recent studies suggest that prenylation inhibition using novel lipophilic bisphosphonates might be active against various malignancies outside the bone metastatic setting. Since prenylation is an important posttranslational modification in RAS protein function we explored the sensitivity of a panel of lung adenocarcinoma cells representing various oncogenic driver mutations. 8 human lung adenocarcinoma cell lines were investigated in vitro to assess the short-term viability and long-term clonogenic potential following zoledronic acid and BPH-1222 treatments. The eight lung cancer cell lines represented wild type (HCC78, CALU3), EGFR- (H1650, H1975) KRAS- (A549, H358), BRAF- (CRL5885) and BRAF + NRAS double mutant (CRL5922) molecular subtypes. Effect on short and long term proliferation were measured with a SRB based photometric assay. Neither short-term nor long-term treatment showed significant differences between the proliferation inhibitory effect of the hydrophilic zoledronic acid and novel lipophilic bisphosphonate BPH-1222. Interestingly, we found that the two KRAS mutant lung adenocarcinoma cell lines were more sensitive in the long-term bisphosphonate treatment assays than non-KRAS mutant cell lines. BRAF or EGFR mutations did not show a differential response against these inhibitors. In vitro proliferation inhibitory efficacies of hydrophilic and lipophilic bisphosphonates were not different in lung adenocarcinoma cells. Nevertheless, due to the different bone accumulation properties of zoledronic acid and lipophilic bisphosphonates further in vivo preclinical studies are warranted to evaluate the inhibitory effect in a more physiological setting.