Adjuvant PSK immunotherapy in patients with carcinoma of the nasopharynx

Coriolus Versicolor and Ganoderma Lucidum Related Natural Products as an Adjunct Therapy for Cancers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Cancer incidence and mortality rates keep rising globally. Coriolus versicolor and Ganoderma lucidum related natural products are commonly applied as a complementary therapeutic option for different stages and types of cancers. The aim of this study is to evaluate the efficacy and safety of the products for cancer therapy. Methods: Randomized controlled trials were identified by systematic search over seven databases from inceptions to May 10, 2019. Two independent reviewers extracted data and assessed the study quality. Meta-analyses were performed to pool hazard ratio (HR), risk ratio (RR), mean differences (MD), and 95% CI using random-effects models. The sources of heterogeneity were explored by subgroup analyses and sensitivity analyses. Publication bias was detected by Funnel plots, Begg's test, and Egger's test. Results: Twenty-three trials involving 4,246 cancer patients were included in this work. C. versicolor and G. lucidum related natural products were significantly associated with lower risks of mortality (HR: 0.82; 95% CI: 0.72, 0.94) and higher total efficacy (RR: 1.30; 95% CI: 1.09, 1.55), but not associated with control rate (RR: 1.05; 95% CI: 0.96, 1.14) compared with control treatment. There was no significant difference between C. versicolor related natural products and control treatment in the effect on relapse-free survival (HR: 1.19; 95% CI: 0.91, 1.55). Compared with control treatment, C. versicolor and G. lucidum related natural products had a favorable effect on elevated levels of CD3 (MD: 9.03%; 95% CI: 2.10, 16.50) and CD4 (MD: 9.2%; 95% CI: 1.01, 17.39), but had no effect on the levels of CD8 (MD: -5.52%; 95% CI: -23.17, 12.13), CD4/CD8 (MD: 0.73; 95% CI:-0.45, 1.91), or NK(MD: 5.87%; 95% CI: -1.06, 12.8). Conclusion: In this meta-analysis, we found that C. versicolor and G. lucidum related natural products might have potential benefits on the overall survival and quality of life in cancer patients.

Vaccine adjuvants as potential cancer immunotherapeutics

Accumulated evidence obtained from various clinical trials and animal studies suggested that cancer vaccines need better adjuvants than those that are currently licensed, which include the most commonly used alum and incomplete Freund's adjuvant, because of either a lack of potent anti-tumor immunity or the induction of undesired immunity. Several clinical trials using immunostimulatory adjuvants, particularly agonistic as well as non-agonistic ligands for TLRs, C-type lectin receptors, retinoic acid-inducible gene I-like receptors and stimulator of interferon genes, have revealed their therapeutic potential not only as vaccine adjuvants but also as anti-tumor agents. Recently, combinations of such immunostimulatory or immunomodulatory adjuvants have shown superior efficacy over their singular use, suggesting that seeking optimal combinations of the currently available or well-characterized adjuvants may provide a better chance for the development of novel adjuvants for cancer immunotherapy.

Polysaccharide peptides from Coriolus versicolor competitively inhibit model cytochrome P450 enzyme probe substrates metabolism in human liver microsomes

Polysaccharide peptide (PSP), isolated from COV-1 strain of Coriolus versicolor, is commonly used as an adjunct in cancer chemotherapy or health supplement in China. Previous studies have shown that PSP decreased antipyrine clearance and inhibited rat CYP2C11-mediated tolbutamide 4-hydroxylation and in human CYP2C9. In this study, the effects of the water extractable fraction of PSP on the metabolism of model CYP1A2, CYP2D6, CYP2E1 and CYP3A4 probe substrates were investigated in pooled human liver microsomes. PSP (1.25-20μM) dose-dependently decreased CYP1A2-mediated metabolism of phenacetin to paracetamol (IC(50) 19.7μM) and CYP3A4-mediated metabolism of testosterone to 6β-hydroxytestosterone (IC(20) 7.06μM). Enzyme kinetics studies showed the inhibition of CYP1A2 activity was competitive and concentration-dependent (K(i)=18.4μM). Inhibition of testosterone to 6β-hydroxytestosterone was also competitive and concentration-dependent (K(i)=31.8μM). Metabolism of dextromethorphan to dextrorphan (CYP2D6-mediated) and chlorzoxazone to 6-hydroxychlorzoxazone (CYP2E1-mediated) was only minimally inhibited by PSP, with IC(20) values at 15.6μM and 11.9μM, respectively. This study demonstrated that PSP competitively inhibited the CYP1A2- and CYP3A4-mediated metabolism of model probe substrates in human liver microsomes in vitro. The relatively high K(i) values for CYP1A2 and CYP3A4 would suggest a low potential for PSP to cause herb-drug interaction related to these CYP isoforms.

Biological mechanism and clinical effect of protein-bound polysaccharide K (KRESTIN(®)): review of development and future perspectives

The mechanism of action of protein-bound polysaccharide K (PSK; KRESTIN(®)) involves the following actions: (1) recovery from immunosuppression induced by humoral factors such as transforming growth factor (TGF)-β or as a result of surgery and chemotherapy; (2) activation of antitumor immune responses including maturation of dendritic cells, correction of Th1/Th2 imbalance, and promotion of interleukin-15 production by monocytes; and (3) enhancement of the antitumor effect of chemotherapy by induction of apoptosis and inhibition of metastasis through direct actions on tumor cells. The clinical effectiveness of PSK has been demonstrated for various cancers. In patients with gastric or colorectal cancer, combined use of PSK with postoperative adjuvant chemotherapy prolongs survival, and this effect has been confirmed in multiple meta-analyses. For small-cell lung carcinoma, PSK in conjunction with chemotherapy prolongs the remission period. In addition, PSK has been shown to be effective against various other cancers, reduce the adverse effects of chemotherapy, and improve quality of life. Future studies should examine the effects of PSK under different host immune conditions and tumor properties, elucidate the mechanism of action exhibited in each situation, and identify biomarkers.

Polysaccharide peptides from Coriolus versicolor competitively inhibit tolbutamide 4-hydroxylation in specific human CYP2C9 isoform and pooled human liver microsomes

Polysaccharide peptide (PSP), isolated from COV-1 strain of Coriolus versicolor, is commonly used as an adjunct in cancer chemotherapy in China. Previous studies have shown that PSP decreased antipyrine clearance and inhibited CYP2C11-mediated tolbutamide 4-hydroxylation in the rat both in vitro and in vivo. In this study, the effects of water extractable fraction of PSP on tolbutamide 4-hydroxylation was investigated in pooled human liver microsomes and in specific human CYP2C9 isoform. PSP (2.5-20μM) dose-dependently decreased the biotransformation of tolbutamide to 4-hydroxy-tolbutamide. Enzyme kinetics studies showed inhibition of tolbutamide 4-hydroxylase activity was competitive and concentration-dependent. In pooled human liver microsomes, PSP had a K(i) value of 14.2μM compared to sulfaphenazole, a human CYP2C9 inhibitor, showed a K(i) value of 0.32μM. In human CYP2C9 isoform, the K(i) value of PSP was 29.5μM and the K(i) value of sulfaphenazole was 0.04μM. This study demonstrated that PSP can competitively inhibit tolbutamide 4-hydroxylation in both pooled human liver microsomes and specific human CYP2C9 in vitro. This study compliments previous findings in the rat that PSP can inhibit human tolbutamide 4-hydroxylase, but the relatively high K(i) values in human CYP2C9 would suggest a low potential for PSP to cause herb-drug interaction.

The effects of beta-glucan on human immune and cancer cells

Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as beta-glucans. beta-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, beta-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by beta-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1-->3 linear beta-glycosidic chain of beta-glucans cannot be digested. Most beta-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small beta-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, beta-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate beta-glucans is essential if we wish to investigate the effects of beta-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified beta-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of beta-glucans or beta-glucans containing compounds.

Effects of polysaccharide peptides from COV-1 strain of Coriolus versicolor on glutathione and glutathione-related enzymes in the mouse

The effects of polysaccharide peptide (PSP), an immunomodulator isolated from Coriolus versicolor COV-1, on glutathione (GSH) and GSH-related enzymes was investigated in C57 mouse. Administration of PSP (1-4 micromole/kg, i.p.) produced a transient, dose-dependent depletion (10-37%) of hepatic GSH, with no effect on serum glutamic-pyruvic transaminase (SGPT) activity. Blood GSH was depleted (6-25%) at 3 h, followed by a rebound increase above the control GSH level (20%) at 18 h. The GSSG/GSH ratio, a measure of oxidative stress, was increased 3 h after PSP treatment but returned to normal levels at 24 h. Sub-chronic treatment of PSP (1-4 micromole/kg/day, i.p.) for seven days did not produce any significant changes in hepatic GSH levels and the GSSG/GSH ratio when measured 24 h after the final dose of PSP. PSP had little effect on glutathione transferase (GST), glutathione reductase (GSSG reductase) and glutathione peroxidase (GPX) activities in the liver. However, a dose-dependent increase in blood GPX activity (30-48%) was observed at 3h, which coincided with the increase in the GSSG/GSH ratio. The increase in blood GPX activity may be a responsive measure to deal with the transient oxidative stress induced by PSP treatment. The results showed that PSP only caused a transient perturbation on hepatic glutathione without affecting the GSH-related enzymes such as GST, GSSG reductase and GPX. The observed changes in blood GSH simply reflected the intra-organ translocation of glutathione, as the glutathione-related enzymes were not significantly affected by PSP treatment.

Polysaccharide peptides from COV-1 strain of Coriolus versicolor inhibit tolbutamide 4-hydroxylation in the rat in vitro and in vivo

Polysaccharide peptide (PSP), isolated from COV-1 strain of Coriolus versicolor, is commonly used as an adjunct in cancer chemotherapy in China. In this study, the effects of whole PSP extract and water extract of PSP on 4-hydroxylation of tolbutamide were investigated in rat liver microsomes in vitro and in vivo in the rat. Both the whole PSP extract and the water soluble fraction (0.5-20 microM) decreased the metabolism of tolbutamide to 4-hydroxytolbutamide in vitro. Enzyme kinetics studies showed that PSP inhibited tolbutamide 4-hydroxylase activity in a competitive, concentration-dependent manner. The whole PSP extract had a Ki value of 12.6 microM and IC50 at 18.4 microM, while the water extract had a Ki value of 6.9 microM and IC50 at 9.8 microM. Sulphaphenazole, a specific human CYP2C9 inhibitor, showed a Ki value of 30.8 microM and IC50 at 44.0 microM in the test system. In the pharmacokinetic studies in vivo, acute PSP (4 micromol/kg, i.p.) treatment did not produce significant changes in tolbutamide clearance, but produced a decrease in the Cinitial (7.4%) and an increase in the Vd (7.4%). Sub-chronic pre-treatment of PSP (1-2 micromol/kg/day, i.p.) for three days did not affect the clearance and AUC of tolbutamide, but the Cinitial was decreased, together with increases in the T1/2, and Vd. The formation of 4-hydroxytolbutamide in vivo was decreased in both acute and sub-chronic studies. Taken together, this study demonstrated the PSP can inhibit tolbutamide 4-hydroxylation both in vitro and in vivo. Despite the fact that CYP isoforms that metabolise tolbutamide are different between rat and human liver due to different catalytic characteristics, and rat studies may not be directly extrapolatable to man, the concomitant use of PSP with other CYP2C substrates should be carefully monitored.

Bioactive polysaccharides from traditional Chinese medicine herbs as anticancer adjuvants

PURPOSE OF STUDY

To review the nature, extent, bioactivities, and clinical application of polysaccharides in Traditional Chinese Medicine (TCM) especially as adjuvants in cancer treatment.

METHODOLOGY

Literature review.

FINDINGS

Many fungal- and plant-derived bioactive polysaccharides with a broad range of immunomodulatory activities are found in TCM. Some such polysaccharides have been developed into drugs and show clinical efficacy in controlled trials while the majority of such compounds remain as nutraceuticals with only preliminary research. Such polysaccharides are generally nontoxic and possess other bioactivities such as inducing differentiation, stimulating hematopoiesis, antimetastasis, and antiangiogenesis, which make them ideal adjuvants in modern cancer therapy.

CONCLUSION

Bioactive polysaccharides occur extensively in TCM herbs and are the basis of potentially useful application of TCM as an adjuvant in cancer therapies.