Abstract 3558: A pilot clinical study of limonene in women with early stage breast cancer: Effects of short-term treatment on tissue limonene disposition and serum markers

Abstract

Abstract Background: Limonene is a highly lipophilic monoterpene found in citrus peel oil that has demonstrated anticancer properties in preclinical studies. The purpose of this study was to evaluate whether limonene and its primary metabolite perillic acid (PA) would distribute extensively to the breast tissue and reach an effective drug concentration. Secondary endpoints included evaluation of changes in cancer-related biomarkers in plasma and tissue. Methods: Participants (N = 40) with newly diagnosed stage 0 - 2 breast cancer took 2 grams daily of oral limonene for 2 - 6 weeks (21.5 ± 8.8 days) prior to planned surgical tumor resection. Blood was drawn pre/post intervention for measurement of serum concentration of limonene, PA, and protein biomarkers, as well as to assess toxicity profiles. A small piece of breast tissue adjacent to the tumor mass was also collected for analysis of limonene and PA levels. Limonene and PA levels in tissue and serum were analyzed using specific chromatography-based assays. Results: Limonene was found to preferentially concentrate in breast tissue (332.3 + 336.1 uM) versus plasma (0.49 + 0.67 uM) with tissue-to-plasma concentration ratio (TPCR) of 1,667 + 312.5 (P<0.001). PA did not concentrate in breast tissue (5.73 + 10.28 uM) versus plasma (3.89 + 6.81 uM) with TPCR of 1.4 + 0.56. Post-intervention serum levels of leptin, adiponectin, TGF-beta1, IGFBP-3 and IL-6 were unchanged from baseline. There was a small but statistically significant post-intervention increase in IGF-1, however the change was no longer significant after adjustment for number of days on agent. Possibly or probably related adverse events were primarily GI-related and were not dose-limiting. No clinically significant changes in complete blood count, renal, hepatic or other blood chemistry studies were noted. Analysis of the intervention effects on tissue biomarkers of proliferation, apoptosis, and cell cycle regulation is ongoing. Discussion: Oral limonene preferentially concentrates in the breast tissue and has a favorable side effect profile. PA does not readily concentrate in breast tissue when administered as oral limonene. Short-term limonene intervention resulted in minimal changes in systemic biomarkers. Further clinical trials with a longer intervention are necessary to establish limonene's potential role as a chemopreventive agent in breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3558. doi:1538-7445.AM2012-3558