D-limonene in patients with advanced cancer

Byron's Comments:

Inititial human studies showing some benefit of D-limonene in cancer patients.

Study Title:

Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer. Cancer Research Campaign Phase I/II Clinical Trials Committee.

Study Abstract:

PURPOSE:

D-Limonene is a natural monoterpene with pronounced chemotherapeutic activity and minimal toxicity in preclinical studies. A phase I clinical trial to assess toxicity, the maximum tolerated dose (MTD) and pharmacokinetics in patients with advanced cancer was followed by a limited phase II evaluation in breast cancer.

METHODS:

A group of 32 patients with refractory solid tumors completed 99 courses of D-limonene 0.5 to 12 g/m2 per day administered orally in 21-day cycles. Pharmacokinetics were analyzed by liquid chromatography-mass spectrometry. Ten additional breast cancer patients received 15 cycles of D-limonene at 8 g/m2 per day. Intratumoral monoterpene levels were measured in two patients.

RESULTS:

The MTD was 8 g/m2 per day; nausea, vomiting and diarrhea were dose limiting. One partial response in a breast cancer patient on 8 g/m2 per day was maintained for 11 months; three patients with colorectal carcinoma had prolonged stable disease. There were no responses in the phase II study. Peak plasma concentration (Cmax) for D-limonene ranged from 10.8+/-6.7 to 20.5+/-11.2 microM. Predominant circulating metabolites were perillic acid (Cmax 20.7+/-13.2 to 71+/-29.3 microM), dihydroperillic acid (Cmax 16.6+/-7.9 to 28.1+/-3.1 microM), limonene-1,2-diol (Cmax 10.1+/-8 to 20.7+/-8.6 microM), uroterpenol (Cmax 14.3+/-1.5 to 45.1+/-1.8 microM), and an isomer of perillic acid. Both isomers of perillic acid, and cis and trans isomers of dihydroperillic acid were in urine hydrolysates. Intratumoral levels of D-limonene and uroterpenol exceeded the corresponding plasma levels. Other metabolites were trace constituents in tissue.

CONCLUSIONS:

D-Limonene is well tolerated in cancer patients at doses which may have clinical activity. The favorable toxicity profile supports further clinical evaluation.

Study Information:

Vigushin DM, Poon GK, Boddy A, English J, Halbert GW, Pagonis C, Jarman M, Coombes RC. Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer. Cancer Research Campaign Phase I/II Clinical Trials Committee. Cancer Chemother Pharmacol. 1998 October 42(2):111-7.
Department of Medical Oncology, Charing Cross Hospital, London, UK.