Ganoderma lucidum for Cancer Treatment

Abstract

The medicinal fungus Ganoderma lucidum has been used in traditional Chinese medicine for millennia to improve health and promote longevity. The idea of using G. lucidum for cancer treatment is based on numerous laboratory and preclinical studies with cancer and immune cells as well as animal models demonstrating various biological activities in vitro and in vivo. For example, G. lucidum possesses cytotoxic, cytostatic, antimetastatic, anti-inflammatory, and immunomodulating activities. Limited clinical studies, including case reports and randomized controlled trials, suggest G. lucidum as an alternative adjunct therapy for stimulating the immune system in cancer patients. To confirm the efficacy of G. lucidum in cancer treatment, systematic translational research programs should be started worldwide. In addition, only standardized preclinically evaluated, biologically active G. lucidum extracts should be used in alternative treatments. This approach will lead to the development of standardized G. lucidum preparations with specific chemical fingerprint-associated anticancer activities.

Introduction

Fungi have been used in traditional Chinese medicines during the past 2 millennia for the prevention or treatment of a variety of diseases. ¹ Nowadays, great attention has been paid to pharmacological research on medicinal fungi. These research fields cover nearly all the pharmacological aspects, such as anticancer effects, anti-inflammatory and immunomodulating effects, effects on cardiovascular and cerebrovascular diseases, effects on diseases of the nervous system, and so on. For example, there are 4 epidemiological studies suggesting that fungi can protect against gastric, gastrointestinal, and breast cancer.^2-5 In addition, Lentinan, a β-(1 → 6) branched β-(1 → 3)-glucan derived from Lentinula edodes, has been clinically used in Japan and China as an adjuvant to cancer treatment. ⁶

There are 1 665 540 new cancer cases and 585 720 cancer deaths projected to occur in the United States in 2014, and certain malignant tumors are a major cause of death. ⁷ The main treatment for cancer patients is using chemotherapy and radiotherapy. However, these 2 routinely used treatments face serious challenges such as drug resistance and toxic side effects. ⁸ To better combat the disease and alleviate adverse effects of chemotherapy or radiotherapy, many people who have been diagnosed with cancer turn to complementary and alternative medicine (CAM). ⁹

Ganoderma lucidum (Lingzhi, Reishi), which has been used for centuries in Asian countries to improve health and promote longevity, is well recognized for the prevention and treatment of many diseases including cancer.^10-12 In 2006, Paterson ¹³ systematically reviewed the therapeutic properties of G. lucidum. Although most of the convincing data are based on laboratory and preclinical studies, G. lucidum has attracted great attention in non-Asian countries. Since the prevalence of G. lucidum used in cancer patients has been increasing, some case reports and randomized controlled trials have been conducted to evaluate the clinical anticancer effects of G. lucidum. It is unfortunate that most of the clinical trials were published in Asian databases and full-text publications are usually not available in English. Up to now, G. lucidum has never been formally regarded as a treatment for cancer. In this review, we provide up-to-date knowledge of G. lucidum in cancer treatment, including existing clinical practice.

Laboratory and Preclinical Studies

Two major groups of biologically active compounds isolated from G. lucidum are triterpenoids (ganoderic acids, ganoderic alcohols, and their derivatives) and polysaccharides (mainly glucans and glycoproteins). ¹⁴ G. lucidum triterpenoids, such as ganoderic acids (GAs), have structural similarity to steroid hormones and exhibit a broad spectrum of anticancer properties.^15,16 Polysaccharides, especially β-D-glucans, have been known to possess anticancer effects, protect normal cells against free radicals, and reduce cell damage caused by mutagens. ¹⁷ According to the latest laboratory and preclinical studies both in vitro and in vivo, the promising anticancer activity of G. lucidum can be attributed to a variety of different mechanisms. ¹⁸

Cytotoxic and Cytostatic Activities

Normal cells divide at a self-regulated rate with restricted controls in the process of the cell cycle. However, when these controls are bypassed, deregulation of the cell cycle underlies aberrant cell reproduction, thus leading to the formation of cancer. ¹⁹ Cycle-phase-specific anticancer drugs have either cytotoxic or cytostatic activities. Cytotoxic drugs, including most of the chemotherapeutics, are toxic to the cells and usually cause DNA damage, resulting in programmed cell death (apoptosis and autophagy). On the other hand, cytostatic drugs can halt the rapid proliferation of cancer cells through their cell cycle to arrest at a certain phase, instead of killing them directly. ²⁰ Yue et al ²¹ indicated that the G. lucidum triterpenes (GTS) treatment regulated expression of 14 proteins in human cervical carcinoma cells, which play important roles in cell proliferation, cell cycle, oxidative stress, and apoptosis. Moreover, GTS induced sensitization of cells to the chemotherapeutic doxorubicin (DOX) by increasing oxidative stress, DNA damage, and apoptosis. In addition, G. lucidum triterpene extract (GLT) not only suppressed proliferation of human colon cancer cells but also inhibited tumor growth in a xenograft model, which was associated with the cell cycle arrest at the G0/G1 phase and induction of the programmed cell death Type II–autophagy. ²²

Besides the total triterpenes extracted from G. lucidum, some isolated and modified triterpenes exhibit significant cytotoxic activities. ²³ Moreover, recent studies identified molecular mechanisms by which triterpenes from G. lucidum affect different cancers (Table 1). Jiang et al ²⁴ originally described suppression of proliferation and colony formation by ganoderic acid A (GA-A), which was associated with the inhibition of transcription factors AP-1 and NF-κB, resulting in the down-regulation of expression of Cdk4 in breast cancer cells. In addition, GA-A also inhibited phosphorylation/activation of transcription factor STAT3, resulting in the enhanced sensitivity of hepatoma cells to cisplatin. ²⁵ Radwan et al ²⁶ recently demonstrated that GA-A induces apoptosis in lymphoma cells through caspase-3 and -9, and enhanced HLA class II-mediated antigen presentation and CD4+ T-cell recognition. Ganoderic acid DM (GA-DM) inhibited cell proliferation; induced DNA damage, cell cycle arrest at the G1 phase, and apoptosis in human breast cancer cells ²⁷ ; induced apoptosis and autophagy; and improved antigen presentation and CD4+ T-cell recognition in melanoma cells. ²⁸ Among other new triterpenes, ganoderic acid Jc (GA-Jc) and ganoderiol F were selectively cytotoxic against leukemia and breast cancer cells, respectively. ²⁹ Ganoderic acid Me (GA-Me) suppressed NF-κB activity and down-regulated expression of genes involved in cell proliferation, apoptosis, invasion, and angiogenesis in breast cancer cells. ³⁰ A pair of positional isomers of ganoderic acids, ganoderic acid Mf (GA-Mf) and ganoderic acid S (GA-S), induced cell cycle arrest and mitochondria-mediated apoptosis in cervical carcinoma cells. ³¹ In addition, new ganoderic acid 3α, 22β-diacetoxy-7α-hydroxyl-5α-lanost-8, 24E-dien-26-oic acid, and ganoderic acids GA-Mc, GA-Mk, GA-Mf, and GA-S were cytotoxic against lung and cervical cancer cells. ³² Moreover, 3 new ganoderic acid T derivatives, TLTO-Ee, TLTO-Pe, and TLTO-A, and 1 known derivative, TLTO-Me, induced cell cycle arrest and demonstrated cytotoxic and pro-apoptotic effects on cervical carcinoma cells in vitro. ³³ Another triterpene, ganoderenic acid D (GAE-D), demonstrated cytotoxicity against cervical, colon, and liver cancer cells. ³⁴ Ganodermanontriol (GDNT), a lanostanoid triterpene alcohol, suppressed proliferation of breast cancer cells and expression of the cell cycle regulatory protein CDC20, which is overexpressed in tumors compared to the surrounding tissue from breast cancer patients. ³⁵ In addition, GDNT also inhibited growth of colon cancer cells in vitro and in vivo through ß-catenin signaling without any side effects. ³⁶ A recent study demonstrated that ethyl lucidenates A, a new triterpenoid isolated from the ethyl acetate fraction of G lucidum, showed cytotoxic activities against human promyelocytic leukemia cells and Burkitt’s lymphoma cells, respectively. ³⁷

Table 1.

Biological Effects of Triterpenes Isolated from Ganoderma lucidum.

Triterpene	Cancer Cells	Mechanism of Action	Target	Reference
3α, 22β-diacetoxy-7α-hydroxyl-5α-lanost-8, 24E-dien-26-oic acid	Cervix: HeLa; lung: 95D	Cytotoxic		32
Ganoderic acid A	Breast: MDA-MB-231	Inhibition of cell proliferation and colony formation, suppression of cell adhesion, migration, invasion	NF-κB, AP-1, Cdk4, uPA, uPAR	24
	Liver: HepG2	Increased sensitivity to cisplatin	STAT3	25
	Lymphoma: NALM-6	Induction of apoptosis	Caspase-3, -9, BIM, BAX	26
Ganoderic acid DM	Breast: MCF-7, MDA-MB-231	Inhibition of cell proliferation and colony formation, cell cycle arrest, induction of apoptosis	Cdk2,–4, cyclin D1, pRb, c-Myc, PARP	27
	Melanoma: J3, HT-144	Induction of apoptosis and autophagy	Caspase-3, -9, Bax	28
			Apaf-1, LC3, beclin-1
Ganoderic acid H	Breast: MDA-MB-231	Inhibition of cell proliferation and colony formation, suppression of cell adhesion, migration, invasion	NF-κB, AP-1, Cdk4, uPA, uPAR	24
Ganoderic acid Jc	Leukemia: HL-60	Cytotoxic		29
	Breast: MCF-7
Ganoderic acid Mc	Cervix: HeLa	Cytotoxic		32
	Lung: 95D
Ganoderic acid Me	Breast: MDA-MB-231	Inhibition of cell proliferation, angiogenesis, and invasion. Induction of apoptosis	NF-κB, c-Myc, cyclin D1, Bcl-2, MMP-9, VEGF, IL-6, -8	30
	Lung: 95D	Inhibition of cell migration	MMP-2/9	49
Ganoderic acid Mf/S	Cervix: HeLa	Cell cycle arrest, induction of apoptosis	Caspase-3, -9, Bax	31
	Lung: 95D	Cytotoxic		32
Ganoderic acid MK	Cervix: HeLa	Cytotoxic		32
	Lung: 95D
Ganoderic acid T; ganoderic acid T derivatives	Colon: HCT-116	Inhibition of cell adhesion and migration	p53, NF-κB, uPA, MMP-2/9, iNOS/NOS2	50
	Cervix: HeLa	Inhibition of cell proliferation, induction of apoptosis	Caspase-3, -9	33
Ganoderenic acid D	Liver: HepG2	Cytotoxic		34
	Cervix: HeLa
	Colon: CaCo-2
Ganodermanontriol	Breast: MDA-MB-231	Inhibition of cell proliferation and colony formation, suppression of cell adhesion, migration, invasion	CDC20, uPA, uPAR	35
	Colon: HCT-116, HT-29	Inhibition of cell proliferation	β-catenin, cyclin-D1, Cdk4, PCNA, E-cadherin	36
Ganoderiol F	Leukemia: HL-60	Cytotoxic		29
	Breast: MCF-7
Ethyl lucidenates A	Leukemia: HL-60	Cytotoxic		37
	Lymphoma: CA46
Lucidenic acid B	Liver: HepG2	Inhibition of cell invasion	NF-κB, AP-1, ERK1/2, MMP-9, c-Jun, c-Fos	52

G. lucidum polysaccharides suppress tumorigenesis and inhibit tumor growth. ³⁸ A novel polysaccharide isolated from Se-enriched G. lucidum (SeGLP-2B-1) suppresses proliferation of different cancer cell lines in vitro and induces mitochondria-mediated apoptosis.^39,40 G. lucidum polysaccharide nanoparticles have significant antitumor efficacy through cytotoxic effects on tumor cells, ⁴¹ and the combination of G. lucidum polysaccharides (LZP-F3) and arsenic trioxide showed synergistic growth inhibition of human urothelial carcinoma cells, which involved induction of the pro-apoptotic pathway. ⁴² Two water-soluble sulfated and carboxymethylated G. lucidum polysaccharide derivatives (S-GL and CM-GL) induced cell cycle arrest at the G2/M phase and suppressed the growth of sarcoma tumor cells in vitro and in vivo with low toxicity to animals. ⁴³

Antimetastatic Activity

Cancer metastasis, the spread of malignant cells from a primary tumor to distant sites, is common in the late stages of cancer and is the major cause of death of patients. ⁴⁴ A complex series of steps, such as cell adhesion, migration, and invasion, is critical for cancer metastasis. Evidence that G. lucidum triterpenoids may have an inhibitory effect on cancer metastasis is increasingly being reported in the scientific literature. A recent study demonstrated that GAEE, a ganoderiol A-enriched extract from G. lucidum, inhibited migration and adhesion of highly metastatic breast cancer cells by suppressing the focal adhesion kinase (FAK)-SRC-Paxillin cascade pathway. ⁴⁵ Oral administration of standardized G. lucidum extract (GLE), containing 6% chemically characterized triterpenes and 13.5% polysaccharides, suppressed breast-to-lung cancer metastases in vivo through the down-regulation of genes responsible for cell invasiveness.^46,47

Structurally related lanostane-type triterpenes ganoderic acid A (GA-A) and H (GA-H) suppressed invasive behavior of breast cancer cells by inhibiting AP-1 and NF-κB signaling and suppressing secretion of uPA. ²⁴ Liu et al. ⁴⁸ isolated GA-DM from the ethanol extracts and showed that GA-DM blocked osteoclastogenesis, which has a high incidence of bone metastasis. Ganoderic acid Me effectively inhibited the invasive behavior of highly metastatic lung and breast cancer cells by down-regulating MMP-2 and MMP-9 gene expression, respectively.^30,49 Ganoderic acid T (GA-T) also inhibited colon cancer cell migration, invasion, and adhesion in vitro through p53 dependent inhibition of MMP expression. ⁵⁰ In addition, GDNT also exerts its effect on anti-invasiveness of breast cancer cells by inhibiting secretion of urokinase-plasminogen activator (uPA) and expression of its receptor (uPAR). ³⁵ Finally, lucidenic acids A, B, C, and N have potential anti-invasive activity in hepatoma cells by suppressing \phorbol-12-myristate-13-acetate (PMA)-induced MMP-9 activity. ⁵¹ Among them, lucidenic acid B (LAB) might inhibit cell invasion by suppressing the phosphorylation of extracellular signal-regulated kinase (ERK1/2) and by reducing AP-1 and NF-κB DNA-binding activities. ⁵²

Anti-inflammatory Activity

Chronic infection and inflammation contribute to around 25% of all cancer cases worldwide. ⁵³ Patients with chronic inflammation have a higher risk of developing cancer, and anti-inflammatory therapy can be used for the prevention and treatment of inflammation-associated cancer. ⁵³ A triterpene-enriched ethanolic extract from G. lucidum demonstrated anti-inflammatory activity in human colon carcinoma cells exposed to pro-inflammatory stimuli. ⁵⁴ Another ethanol extract from the mycelium of G. lucidum showed anti-inflammatory activity against carrageenan-induced (acute) and formalin-induced (chronic) inflammation in mouse and phorbol ester–induced mouse skin inflammation. ⁵⁵ G. lucidum triterpene extract showed anti-inflammatory effects in macrophages, which were mediated by the inhibition of NF-κB and AP-1 signaling pathways. ⁵⁶ In addition, colitis-associated carcinogenesis in mice can also be prevented by GLT. ⁵⁷

On the other hand, G. lucidum polysaccharides (GLP) also showed significant anti-inflammatory activity in acute and chronic inflammation in in vivo models. ⁵⁸ Lin et al ⁵⁹ evaluated an extract of G. lucidum polysaccharides (EORP) and concluded that EORP attenuated lipopolysaccharide (LPS)-induced expression of adhesion molecule and monocyte adherence by suppressing ERK phosphorylation and NF-κB activation in vitro and in vivo.

Immunomodulating Activity

The anticancer effects of G lucidum polysaccharides are believed to modulate immune cell response, which further targets cancer cells. ⁶⁰ Specifically, G. lucidum polysaccharides affect immune cells and immune-related cells such as T lymphocytes, B lymphocytes, macrophages, dendritic cells, and natural killer cells. ³⁸ Tumor cells produce factors such as transforming growth factor (TGF)-β1, interleukin (IL)-10, and vascular endothelial growth factor (VEGF), which can inhibit the function of immune cells. Sun et al ⁶¹ demonstrated that G. lucidum polysaccharides (Gl-PS) have counteractive effects against suppression induced by culture supernatant of melanoma cells on CD71 and FasL, 2 important molecules that are expressed upon lymphocyte activation. In addition, Gl-PS fully or partially reversed lymphocyte suppression induced by plasma from lung cancer patients. ⁶² Moreover, Gl-PS antagonizes the suppression induced by culture supernatant of melanoma cells on viability, nitric oxide (NO) production, phagocytic activity, tumor necrosis factor alpha (TNF-α) production, and activity of peritoneal macrophages. ⁶³ Guo et al ⁶⁴ extracted a water-soluble polysaccharide (GSG) from the spores of G. lucidum and suggested that it can effectively induce IL-6 and TNF-α secretion in murine resident peritoneal macrophages, which is partially mediated by the glucan receptor, Dectin-1, and MAPKs- and Syk-dependent pathway. On the other hand, immunomodulating activity of GLP was demonstrated by the reduction of IL-6 and TNF-α levels and increased concentration of IL-2, IL-4, and IL-10 in serum of rats with gastric cancer. ⁶⁵

Besides the G. lucidum polysaccharides, it has been published that G. lucidum triterpenes (lucidenic acids rich extract) can also enhance immune responses in human monocytes possibly through modulation of MAP kinases p38 and JNK, which is independent of NF-κB activation. ⁶⁶

Bioavailability and Pharmacokinetics

Ganoderic acids GA-C2, GA-B, GA-K, and GA-H were detected in rat plasma after oral administration of G. lucidum extract using high-performance liquid chromatography. ⁶⁷ Liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) was used for the detection of ganoderiol F in plasma after oral or intravenous application. ⁶⁸ Postbiosynthetic stable isotope encoding technique enabled the detection of several ganoderic acids in rat plasma after oral application. ⁴⁷ Ganoderic acids GA-A and GA-F were detected in plasma of the male volunteers after oral application of a G. lucidum extract. ⁶⁹ Based on the application, extracts used, triterpenes, and their concentrations, different triterpenes were detected in plasma in a range of minutes and eliminated in more than 2 hours.

G. lucidum triterpenes were also detected in rat bile after their oral application. ⁷⁰ Triterpenes are metabolized through phases I and II metabolism in rats before being excreted into the bile. This metabolic transformation includes reduction, oxidation, deacetylation, desaturation, hydroxylation, sulfation, and glucuronidation as demonstrated on the metabolism of GA-D and GA-C2.^71,72 Although the major metabolite of GA-D is GA-B, ⁷³ GA-B is further metabolized and several metabolites of GA-B were also detected in rat kidney and stomach. ⁷⁴ The low polar ganoderic acids were transformed into the high polar metabolites, which are eliminated from the organism. ⁷⁵ On the other hand, ganoderiol F is metabolized into ganodermadiol by an anaerobic incubation with bacterial mixtures and was therefore detected in rat feces, but not in plasma and urine. ⁶⁸

Although the pharmacokinetics of other fungal polysaccharides were previously evaluated, ⁷⁶ the bioavailability of G. lucidum polysaccharides remains to be determined.

Case Reports

In spite of the fact that G. lucidum is widely used as a traditional Chinese medicine, there are only a handful of case reports of G. lucidum or related CAM used in patients with different cancers. Although the efficacy of G. lucidum in cancer patients was reported, clinical observations are needed and it should be used with caution in patients when combined with chemotherapy. In addition, complete safety analysis on G. lucidum is necessary.

Hepatocellular Carcinoma

There is no systemic therapy showing a survival benefit for patients with advanced or metastatic hepatocellular carcinoma (HCC). ⁷⁷ A 69-year-old male patient with chronic hepatitis B infection developed HCC. He began taking G. lucidum and another herbal preparation, Gan Fu Le, which contained 21 kinds of Chinese medicine, soon after the diagnosis. After 3 months, the liver mass was dramatically reduced and the tumor size decreased in the first several years. During the following 10 years, these treatments caused long-lasting HCC remission, and only mild renal insufficiency and hypertension were observed. Moreover, the level of α-fetoprotein (AFP) in serum, which is the most widely used tumor marker for detecting patients with HCC, was never significantly elevated. ⁷⁸ However, ascribing the effects of G. lucidum was impossible because of the additional preparation.

Another case is a 72-year-old female patient with a high level of AFP, who was diagnosed with multiple malignant liver lesions and a single metastatic lesion. Because of the poor performance status and limited therapeutic options, she took G. lucidum and Pian Zhi Huang (a traditional Chinese medicine preparation including musk, bezoar, snake gall, pseudo-ginseng, and so on) continually. Twelve months after diagnosis, her dominant lesion had shrunk, which was associated with a decrease in the AFP levels. ⁷⁸ However, in the third case of a 78-year-old male patient with metastatic HCC, ⁷⁸ the AFP level continued to increase after G. lucidum treatment until the chemotherapeutic agent doxorubicin was discontinued. The possible conflicting interactions between these 2 agents might affect the clinical outcomes and should be avoided.

Prostate Cancer

A 63-year-old male patient with prostate cancer was treated with Genistein Combined Polysaccharide (GCP) 1.5 g/d orally for 6 weeks prior to radical prostatectomy. The prostate specific antigen (PSA) decreased from 19.7 to 4.2 ng/mL and no cancer was detected in the prostatectomy specimen. ⁷⁹ Genistein Combined Polysaccharide is an aglycone isoflavones-rich extract produced by culturing soybean extract with mycelia from G. lucidum, which produces beta-glucosidase and cleaves glucoside forms of isoflavones into more biologically active aglycone forms. ⁸⁰ Therefore, the anticancer effect might be associated with the biological activity of isoflavones. However, a recent study with GCP showed that it did not decrease PSA levels in men with low-volume prostate cancer. ⁸¹ Again, the contribution from G. lucidum remains unknown.

Lymphoma

A complete regression of high-grade gastric large B-cell lymphoma 11 days after a biopsy diagnosis and Helicobacter eradication therapy in a previously healthy 47-year-old male patient was described, which is extremely rare. ⁸² It is interesting that the gastrectomy specimen was densely infiltrated with CD3 (+) CD8 (+) cytotoxic small T-lymphocytes. Since the patient ingested unspecified megadoses of G. lucidum (60 capsules daily for 5 days) and the initial biopsy showed only an insignificant amount of T-lymphocytes, it is possible that G. lucidum induced production of cytotoxic T-cells and this active host immune response led to the regression of B-cell lymphoma. ⁸²

G. lucidum spore (GLS) is a CAM that is widely used by cancer patients in China. A 49-year-old male patient with non-Hodgkins lymphoma had a history of consuming powdered G. lucidum extract, which contained GLS as a dietary supplement. He presented with chronic watery diarrhea, but after discontinuing GLS ingestion, the diarrheal symptoms improved. ⁸³

Gastrointestinal Cancer

Although there seems to be no or very few acute side effects during the application of G. lucidum, ⁹ an increased level of the serum tumor marker CA72-4, which is used for monitoring therapeutic response in patients receiving gastrointestinal cancer treatment, was identified in 5 cases of gastrointestinal cancer patients after oral ingestion of GLS with multiple therapies.^84,85 The level of CA72-4 returned to normal rapidly when the supplement was discontinued. The mechanisms of this reaction are still unknown. ⁸⁴

Clinical Studies

Clinical studies of G. lucidum on patients with cancer are limited and results are reported inadequately in some aspects. In 2012, the Cochrane Collaboration reviewed a set of databases for randomized controlled trials (RCTs) of G. lucidum for cancer treatment, but only 5 RCTs of 257 studies met the inclusion criteria (all types and stages of cancer, comparison of G. lucidum efficacy to active or placebo control in patients with cancer diagnosed by pathology) and all groups of patients came from Asian countries. ⁹ Based on these 5 studies with uncharacterized or partially characterized polysaccharide extracts, the authors concluded that there is insufficient evidence to justify the use of G. lucidum for cancer treatment. ⁹ However, G. lucidum can be used as an alternative adjunct to stimulate host immunity. ⁹ Finally, a recent study demonstrated that 5 of 15 gynecologic cancer patients achieved stable disease after ingestion of G. lucidum fruiting body or spore extract. ⁸⁶

Conclusion

Many laboratory and preclinical studies demonstrate that G. lucidum has great potential in cancer treatment. However, clinical studies do not support the use of G. lucidum as a first-line treatment for cancer.

Therefore, a strong, systematic, and worldwide translational research program should be started, applying the present knowledge from in vitro and animal experiments to clinical research (from bench to bedside). The major problem of published clinical studies is the lack of using purified compounds or properly characterized extracts. Since the compositions and amounts of the biologically active molecules, including triterpenes and polysaccharides, depend on the specific G. lucidum strains, growing conditions, and extraction methods, the active ingredients of commercial G. lucidum products should be quantified and listed.

The majority of clinical trials demonstrating stimulation of the immune system contained polysaccharides in G. lucidum preparations. However, strong laboratory and preclinical studies suggest that several purified triterpenes or G. lucidum extracts containing triterpenes have direct anticancer activity by modulating signaling in cancer cells. Therefore, future clinical trials with G. lucidum should be performed only with characterized extracts with specified amounts of active compounds. These extracts need to be (1) evaluated in in vitro and in vivo laboratory studies and (2) chemically characterized (eg, by LC/MS/MS analysis) to determine the exact amount of specific triterpenes and other molecules to develop an “activity-associated fingerprint.” This fingerprint will be used for the standardization of G. lucidum preparations for the clinical studies.

Experiments with purified G lucidum triterpenes are showing promising results in vivo, and this knowledge can be used for drug development. However, the use of whole G. lucidum preparations in CAM is more desirable as the specific components in G lucidum could have synergistic or additive effects and could affect more signaling pathways and molecular targets, finally leading to the demise of cancer cells.