CAM and Cancer

CAM and Cancer

Between 30 – 70% of cancer patients turn to complementary and alternative medicine (CAM) approaches for treatment and support (Goldstein et al 2008). Botanicals and herbal preparations are among the most common CAM approaches used by cancer patients both for cancer treatment and management of cancer symptoms. In a recent review of cancer patients in California, 86.5% were using more than two dietary supplements, which included herbal preparations (ibid). However, only a minority of patients uses dietary supplements and botanicals for cancer treatment, rather than to manage associated symptoms or related health conditions. This paper reviews the state of the clinical science of botanicals used in CAM for treatment of cancer and cancer symptoms, although the role of botanicals for cancer prevention is not a focus of this article. Considering the expansive nature of the field and the fact that a substantial part of the literature especially on botanicals used in Asian countries has not been published in English, this article focuses on clinical research data published in English suggesting clinical benefit of botanicals used in CAM cancer treatment and the discussion of continuing, promising clinical research projects of botanicals for cancer.

Botanicals used in traditional Chinese medicine

Indirubin (Qing Dai)

Indigo naturalis (2,2? bisindole) was identified as the active ingredient of Qing Dai in the traditional Chinese medicine prescription Danggui Longhui Wan (Xiao? et al, 2002; Eisenbrand? et al 2004) and has been used for the treatment of a number of diseases including chronic myelocyctic leukaemia.

Indirubin is the dark red 3,2?-isomer and by-product of indigo naturalis (Eisenbrand? et al, 2004). Natural sources include indigo producing plants such as Isatis tinctoria L. (dyer’s woad), mollusks of the Muricidae family and bacteria (Xiao? et al, 2002). Indirubins may act through the aryl hydrocarbon receptor AhR as well as through CDKs, GSK-3 and others, resulting in cell cycle arrest (Knockaert et al, 2004). However, recent studies suggest that some indirubin derivatives may induce cell death through non-apoptotic mechanisms (Ribas? et al 2006).

A synthetic oxime ether derivative of indirubin, termed BIO-112, is undergoing testing in Phase II clinical trials for leukaemia in Europe (Pharmaprojects 2008).

Scutellaria barbata D. Don (Ban Zhi Lian)

The aerial part of Scutellaria barbata was used to produce an aqueous extract BZL 101, which has recently undergone testing in a Phase I trial for patients with advanced breast cancer (Rugo? et al 2007) with promising results. Preclinical studies found induction of apoptosis in breast cancer cell lines exposed to BLZ 101. This extract is being moved into Phase II clinical trials in breast and ovarian cancers (Pharmaprojects 2008).

Tripterygium wilfordii Hook. f. (triptolide) (Le Gong Teng)

Triptolide, a diterpine triepoxide derived from the Chinese plant Tripterygium wilfordii, is an inhibitor of heat shock transcription factor 1 (HSF1). HSF1 inhibition may sensitise cells to stress-induced apoptosis (Westerheide? et al 2006), making triptolide a promising anticancer agent. The triptolide derivative omtriptolide is now being developed in early phase clinical trials for the treatment of acute myelogenous leukaemia (Pharmaprojects 2008).

Cephalotaxus harringtonia (Knight ex Forbes) K. Koch (homoherringtonine)

Homoharringtonine is an ester of cephalotaxine found in a number of Cephalotaxus species, evergreen coniferous shrubs that have been used in Chinese medicine for the treatment of cancer (Efferth? et al 2007). Homoharringtonine has showed promising result in chronic myeloid leukaemia in early phase clinical studies as a single agent and in combination with IFN-? resulting in significant myelotoxicity (O’Brien? et al 2002; O’Brien? et al, 1999; O’Brien? et al 1995). With the advent of the more effective and better tolerated imatinib, further development of homoherringtonine has been limited. The agent has received increased attention again recently based on promising results in the treatment of imatinib-refractory chronic myeloid leukaemia (Quintas-Cardama? et al 2007). Homoharringtonine is susceptible to MDR1 extrusion (Efferth? et al 2007).

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