Group items tagged

We sought to systematically evaluate the evidence base for all new drugs and new indications for the treatment of solid tumours and haematological malignancies approved by the EMA in the five year period 2009-13

Three investigators (AP, EP, and EG) independently extracted data on and descriptively analysed the following trial features: characteristics of the participant population, study design (randomisation, crossover from experimental to control group, and blinding of investigators and participants), experimental and control groups, enrolment, primary and secondary endpoints, magnitude of benefit on survival and quality of life, and narrative interpretation of the findings

Only 18 of the 68 (26%) were supported by a pivotal study powered to evaluate overall survival as the primary outcome

From 2009 to 2013, the EMA approved use of 48 oncology drugs

Seventeen drugs were approved for treatment of haematological malignancies and 51 for treatment of solid tumours

Overall, 72 clinical trials supported the approval of 68 novel drug uses

Our scoring was limited to drugs for solid tumours

Among 68 cancer drug indications approved by the EMA in the period 2009-13, and with a median of 5.4 years’ follow-up, only 35 (51%) were associated with a significant improvement in survival (26/35) or quality of life (9/35) over existing treatment options, placebo, or as add on treatment

Only two of the 26 drugs shown to extend life also showed benefits on quality of life

33 (49%) had not shown any improvement on survival or quality of life

This systematic evaluation of oncology drug approvals by the EMA in 2009-13 shows that most of the drugs (39/68, 57%) entered the market without evidence of improved survival or quality of life

At a minimum 3.3 years after market entry, there was still no conclusive evidence that 33 of these 39 cancer drugs either extended or improved life

What are potential reasons for the paucity of drug approvals with demonstrable survival advantages over existing treatments?

Firstly, only 18 (26%) indications for use in our cohort were supported by trials in which extension of life was the primary outcome

None of the pivotal studies supporting oncology drug approvals from 2009 to 2013 included quality of life as a primary outcome measure

Most new oncology drugs authorised by the EMA in 2009-13 came onto the market without clear evidence that they improved the quality or quantity of patients’ lives

Ki-67 is also expressed at low levels (<3 % of cells) in ER-negative cells, but not in ER-positive cells

A meta-analysis involving 12,155 patients demonstrated that the Ki-67 positivity confers a higher risk of recurrence and a worse survival rate in patients with early breast cancer.

high levels of Ki-67 are associated with worse prognoses

Ki-67 was associated with worse survival rates

associated with proliferation

higher tumor stages and higher nodal status were associated with higher Ki-67 quartiles indicating that the more aggressive the tumor is the higher is the percentage of cells positively stained for Ki-67

Previous studies were able to demonstrate that a prognostic model, the IHC 4 score, using ER, PR, HER2, and Ki-67 provides similar prognostic information to that in the 21-gene Genomic Health recurrence score

ER status has been largely identified as being inversely correlated with Ki-67, with the higher rates of ER positivity shown in the lowest proliferating tumors

high levels of Ki-67 are associated with HER2/-neu positivity according to former studies

higher values of Ki-67-labeling index were associated with adverse prognostic factors

Ki-67-labeling index was associated with larger tumors, higher tumor grade, peritumoral vascular invasion, and HER-2 positivity

The serum level of LDH correlated with tumor burden and was thought to reflect the tumor’s growth and invasive potential

the majority of patients with advanced or metastatic disease could be detected to have extremely high serum level of LDH

strong evidence to support effective chemotherapy of full dose even in patients with high LDH level

LDH is a key enzyme in the process of energy production in cancer cells, it catalyzes the conversion of pyruvate to lactate in hypoxic conditions

its function in anaerobic metabolism, cancer cells grow even after their rapid proliferation that leads to low-oxygen conditions in the tumor microenvironment

LDH plays an important role in tumor progression and maintenance

inhibition of LDH inhibits tumor progression and has been considered for the therapeutic target of cancer energy metabolism

LDH levels are increased in response to tissue injury or during disease states

LDH could be a marker of tumor burden for advanced cancer patients

Under steady-state conditions, intracellular GSH is maintained at millimolar concentrations, which keeps cells in a reduced environment and serves as the principal intracellular redox buffer when cells are subjected to an oxidative stressor including H2O2 (26). Glutathione peroxidase (GPx) activity catalyzes the reduction of H2O2 to water with the conversion of GSH to glutathione disulfide (GSSG). Under steady-state conditions, GSSG is recycled back to GSH by glutathione disulfide reductase using reducing equivalents from NADPH. However, under conditions of increased H2O2 flux, this recycling mechanism may become overwhelmed leading to a depletion of intracellular GSH (27, 28).

ascorbate radiosensitization can create an overwhelming oxidative stress to pancreatic cancer cells resulting in oxidation/depletion of the GSH intracellular redox buffer, resulting in cell death.

Treatment with the combination of ascorbate + IR significantly delayed tumor growth compared to controls or ascorbate alone

Ascorbate + IR also significantly increased overall survival compared to controls, IR alone or ascorbate alone

54% of mice treated with the combination of IR + ascorbate had no measurable tumors

Glutathione is a measurable marker indicative of the oxidation state of the thiol redox buffer in cells. In severe systemic oxidative stress, the GSSG/2GSH couple may become oxidized, i.e. the concentration of GSH decreases and GSSG may increase because the capacity to recycle GSSG to GSH becomes rate-limiting

This suggests that the very high levels of pharmacological ascorbate in these experiments may have a pro-oxidant toward red blood cells as seen by a decrease in the capacity of the intracellular redox buffer

These data support the hypothesis that ascorbate radiosensitization does not cause an increase in oxidative damage from lipid-derived aldehydes to other organs.

Our current study demonstrates the potential for pharmacological ascorbate as a radiosensitizer in the treatment of pancreatic cancer.

pharmacological ascorbate enhances IR-induced cell killing and DNA fragmentation leading to induction of apoptosis in HL60 leukemia cells

pharmacological ascorbate significantly decreases clonogenic survival and inhibits the growth of all pancreatic cancer cell lines as a single agent, as well as sensitizes cancer cells to IR

Hurst et al. demonstrated that pharmacological ascorbate combined with IR leads to increased numbers of double-strand DNA breaks and cell cycle arrest when compared to either treatment alone

pharmacological ascorbate could serve as a “pro-drug” for the delivery of H2O2 to tumors

the double-strand breaks induced by H2O2 were more slowly repaired

The combination of ascorbate and IR provide two distinct mechanisms of action: ascorbate-induced toxicity due to extracellular production of H2O2 that then diffuses into cells and causes damage to DNA, protein, and lipids; and radiation-induced toxicity as a result of ROS-induced damage to DNA. In addition, redox metal metals like Fe2+ may play an important role in ascorbate-induced cytotoxicity. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of H2O2; labile iron can also react with H2O2. Recently our group has demonstrated that pharmacological ascorbate and IR increase the labile iron in tumor homogenates from this murine model of pancreatic cancer

we demonstrated that ascorbate or IR alone decreased tumor growth, but the combination treatment further inhibited tumor growth, indicating that pharmacological ascorbate is an effective radiosensitizer in vivo

data suggest that pharmacological ascorbate may protect the gut locally by decreasing IR-induced damage to the crypt cells, and systemically, by ameliorating increases in TNF-α

Data from the American Cancer Society show that the rate of increase in cancer deaths/year (3.4%) was two-fold greater than the rate of increase in new cases/year (1.7%) from 2013 to 2017

cancer is predicted to overtake heart disease as the leading cause of death in Western societies

cancer can also be recognized as a metabolic disease.

glucose is first split into two molecules of pyruvate through the Embden–Meyerhof–Parnas glycolytic pathway in the cytosol

Aerobic fermentation, on the other hand, involves the production of lactic acid under normoxic conditions

persistent lactic acid production in the presence of adequate oxygen is indicative of abnormal respiration

Otto Warburg first proposed that all cancers arise from damage to cellular respiration

The Crabtree effect is an artifact of the in vitro environment and involves the glucose-induced suppression of respiration with a corresponding elevation of lactic acid production even under hyperoxic (pO2 = 120–160 mmHg) conditions associated with cell culture

the Warburg theory of insufficient aerobic respiration remains as the most credible explanation for the origin of tumor cells [2, 37, 51, 52, 53, 54, 55, 56, 57].

The main points of Warburg’s theory are; 1) insufficient respiration is the predisposing initiator of tumorigenesis and ultimately cancer, 2) energy through glycolysis gradually compensates for insufficient energy through respiration, 3) cancer cells continue to produce lactic acid in the presence of oxygen, and 4) respiratory insufficiency eventually becomes irreversible

Efraim Racker coined the term “Warburg effect”, which refers to the aerobic glycolysis that occurs in cancer cells

Warburg clearly demonstrated that aerobic fermentation (aerobic glycolysis) is an effect, and not the cause, of insufficient respiration

all tumor cells that have been examined to date contain abnormalities in the content or composition of cardiolipin

The evidence supporting Warburg’s original theory comes from a broad range of cancers and is now overwhelming

respiratory insufficiency, arising from any number mitochondrial defects, can contribute to the fermentation metabolism seen in tumor cells.

data from the nuclear and mitochondrial transfer experiments suggest that oncogene changes are effects, rather than causes, of tumorigenesis

Normal mitochondria can suppress tumorigenesis, whereas abnormal mitochondria can enhance tumorigenesis

In addition to glucose, cancer cells also rely heavily on glutamine for growth and survival

Glutamine is anapleurotic and can be rapidly metabolized to glutamate and then to α-ketoglutarate for entry into the TCA cycle

Glucose and glutamine act synergistically for driving rapid tumor cell growth

Glutamine metabolism can produce ATP from the TCA cycle under aerobic conditions

Amino acid fermentation can generate energy through TCA cycle substrate level phosphorylation under hypoxic conditions

Hif-1α stabilization enhances aerobic fermentation

targeting glucose and glutamine will deprive the microenvironment of fermentable fuels

Although Warburg’s hypothesis on the origin of cancer has created confusion and controversy [37, 38, 39, 40], his hypothesis has never been disproved

Warburg referred to the phenomenon of enhanced glycolysis in cancer cells as “aerobic fermentation” to highlight the abnormal production of lactic acid in the presence of oxygen

Emerging evidence indicates that macrophages, or their fusion hybridization with neoplastic stem cells, are the origin of metastatic cancer cells

Radiation therapy can enhance fusion hybridization that could increase risk for invasive and metastatic tumor cells

Kamphorst et al. in showing that pancreatic ductal adenocarcinoma cells could obtain glutamine under nutrient poor conditions through lysosomal digestion of extracellular proteins

It will therefore become necessary to also target lysosomal digestion, under reduced glucose and glutamine conditions, to effectively manage those invasive and metastatic cancers that express cannibalism and phagocytosis.

Previous studies in yeast and mammalian cells show that disruption of aerobic respiration can cause mutations (loss of heterozygosity, chromosome instability, and epigenetic modifications etc.) in the nuclear genome

The somatic mutations and genomic instability seen in tumor cells thus arise from a protracted reliance on fermentation energy metabolism and a disruption of redox balance through excess oxidative stress.

According to the mitochondrial metabolic theory of cancer, the large genomic heterogeneity seen in tumor cells arises as a consequence, rather than as a cause, of mitochondrial dysfunction

A therapeutic strategy targeting the metabolic abnormality common to most tumor cells should therefore be more effective in managing cancer than would a strategy targeting genetic mutations that vary widely between tumors of the same histological grade and even within the same tumor

Tumor cells are more fit than normal cells to survive in the hypoxic niche of the tumor microenvironment

Hypoxic adaptation of tumor cells allows for them to avoid apoptosis due to their metabolic reprograming following a gradual loss of respiratory function

The high rates of tumor cell glycolysis and glutaminolysis will also make them resistant to apoptosis, ROS, and chemotherapy drugs

Despite having high levels of ROS, glutamate-derived from glutamine contributes to glutathione production that can protect tumor cells from ROS

It is clear that adaptability to environmental stress is greater in normal cells than in tumor cells, as normal cells can transition from the metabolism of glucose to the metabolism of ketone bodies when glucose becomes limiting

Mitochondrial respiratory chain defects will prevent tumor cells from using ketone bodies for energy

glycolysis-dependent tumor cells are less adaptable to metabolic stress than are the normal cells. This vulnerability can be exploited for targeting tumor cell energy metabolism

In contrast to dietary energy reduction, radiation and toxic drugs can damage the microenvironment and transform normal cells into tumor cells while also creating tumor cells that become highly resistant to drugs and radiation

Drug-resistant tumor cells arise in large part from the damage to respiration in bystander pre-cancerous cells

Because energy generated through substrate level phosphorylation is greater in tumor cells than in normal cells, tumor cells are more dependent than normal cells on the availability of fermentable fuels (glucose and glutamine)

Ketone bodies and fats are non-fermentable fuels

Although some tumor cells might appear to oxidize ketone bodies by the presence of ketolytic enzymes [181], it is not clear if ketone bodies and fats can provide sufficient energy for cell viability in the absence of glucose and glutamine

Apoptosis under energy stress is greater in tumor cells than in normal cells

A calorie restricted ketogenic diet or dietary energy reduction creates chronic metabolic stress in the body

. This energy stress acts as a press disturbance

Drugs that target availability of glucose and glutamine would act as pulse disturbances

Hyperbaric oxygen therapy can also be considered another pulse disturbance

The KD can more effectively reduce glucose and elevate blood ketone bodies than can CR alone making the KD potentially more therapeutic against tumors than CR

Campbell showed that tumor growth in rats is greater under high protein (>20%) than under low protein content (<10%) in the diet

Protein amino acids can be metabolized to glucose through the Cori cycle

The fats in KDs used clinically also contain more medium chain triglycerides

Calorie restriction, fasting, and restricted KDs are anti-angiogenic, anti-inflammatory, and pro-apoptotic and thus can target and eliminate tumor cells through multiple mechanisms

Ketogenic diets can also spare muscle protein, enhance immunity, and delay cancer cachexia, which is a major problem in managing metastatic cancer

GKI values of 1.0 or below are considered therapeutic

The GKI can therefore serve as a biomarker to assess the therapeutic efficacy of various diets in a broad range of cancers.

It is important to remember that insulin drives glycolysis through stimulation of the pyruvate dehydrogenase complex

The water-soluble ketone bodies (D-β-hydroxybutyrate and acetoacetate) are produced largely in the liver from adipocyte-derived fatty acids and ketogenic dietary fat. Ketone bodies bypass glycolysis and directly enter the mitochondria for metabolism to acetyl-CoA

Due to mitochondrial defects, tumor cells cannot exploit the therapeutic benefits of burning ketone bodies as normal cells would

Therapeutic ketosis with racemic ketone esters can also make it feasible to safely sustain hypoglycemia for inducing metabolic stress on cancer cells

ketone bodies can inhibit histone deacetylases (HDAC) [229]. HDAC inhibitors play a role in targeting the cancer epigenome

Therapeutic ketosis reduces circulating inflammatory markers, and ketones directly inhibit the NLRP3 inflammasome, an important pro-inflammatory pathway linked to carcinogenesis and an important target for cancer treatment response

Chronic psychological stress is known to promote tumorigenesis through elevations of blood glucose, glucocorticoids, catecholamines, and insulin-like growth factor (IGF-1)

In addition to calorie-restricted ketogenic diets, psychological stress management involving exercise, yoga, music etc. also act as press disturbances that can help reduce fatigue, depression, and anxiety in cancer patients and in animal models

Ketone supplementation has also been shown to reduce anxiety behavior in animal models

This physiological state also enhances the efficacy of chemotherapy and radiation therapy, while reducing the side effects

lower dosages of chemotherapeutic drugs can be used when administered together with calorie restriction or restricted ketogenic diets (KD-R)

Besides 2-DG, a range of other glycolysis inhibitors might also produce similar therapeutic effects when combined with the KD-R including 3-bromopyruvate, oxaloacetate, and lonidamine

A synergistic interaction of the KD diet plus radiation was seen

It is important to recognize, however, that the radiotherapy used in glioma patients can damage the respiration of normal cells and increase availability of glutamine in the microenvironment, which can increase risk of tumor recurrence especially when used together with the steroid drug dexamethasone

Poff and colleagues demonstrated that hyperbaric oxygen therapy (HBOT) enhanced the ability of the KD to reduce tumor growth and metastasis

HBOT also increases oxidative stress and membrane lipid peroxidation of GBM cells in vitro

The effects of the KD and HBOT can be enhanced with administration of exogenous ketones, which further suppressed tumor growth and metastasis

Besides HBOT, intravenous vitamin C and dichloroacetate (DCA) can also be used with the KD to selectively increase oxidative stress in tumor cells

Recent evidence also shows that ketone supplementation may enhance or preserve overall physical and mental health

Some tumors use glucose as a prime fuel for growth, whereas other tumors use glutamine as a prime fuel [102, 186, 262, 263, 264]. Glutamine-dependent tumors are generally less detectable than glucose-dependent under FDG-PET imaging, but could be detected under glutamine-based PET imaging

GBM and use glutamine as a major fuel

Many of the current treatments used for cancer management are based on the view that cancer is a genetic disease

Emerging evidence indicates that cancer is a mitochondrial metabolic disease that depends on availability of fermentable fuels for tumor cell growth and survival

Glucose and glutamine are the most abundant fermentable fuels present in the circulation and in the tumor microenvironment

Low-carbohydrate, high fat-ketogenic diets coupled with glycolysis inhibitors will reduce metabolic flux through the glycolytic and pentose phosphate pathways needed for synthesis of ATP, lipids, glutathione, and nucleotides

Previous studies showed that GBM survival and tumor growth was correlated with blood glucose levels

Evidence indicates that glioma cells cannot effectively use ketone bodies for energy due to defects in the number, structure, and function of their mitochondria

The accuracy of the GKI as a predictor for therapeutic efficacy, however, is better when ketone bodies are measured from the blood than when measured from the urine

A reduction of glucose-driven lactic acid fermentation would not only increase tumor cell apoptosis, but would also reduce inflammation and edema in the tumor microenvironment thus reducing tumor cell angiogenesis and invasion

Besides serving as a metabolic fuel for GBM, glutamine is also an essential metabolite for normal immune cells

therapies that inhibit glutamine availability and utilization must be strategically employed to avoid inadvertent impairment of immune cell functions

we used the non-toxic green tea extract, EGCG, and chloroquine in an attempt to limit glutamine availability to the tumor cells

EGCG is thought to target the glutamate dehydrogenase activity that facilitates glutamine metabolism in GBM cells

Chloroquine, on the other hand, will inhibit lysosomal digestion thus restricting fermentable amino acids and carbohydrates from phagocytosed materials in the tumor microenvironment

HBOT to increase oxidative stress in the tumor cells

As glucose and glutamine fermentation protect tumor cells from oxidative stress, reduced availability of these metabolites under ketosis could enhance the therapeutic action of HBOT, as we recently described

Prior to subtotal tumor resection and standard of care (SOC), the patient conducted a 72-h water-only fast

Following the fast, the patient initiated a vitamin/mineral-supplemented ketogenic diet (KD) for 21 days that delivered 900 kcal/day

KD (increased to 1,500 kcal/day at day 22

the patient received metformin (1,000 mg/day), methylfolate (1,000 mg/day), chloroquine phosphate (150 mg/day), epigallocatechin gallate (400 mg/day), and hyperbaric oxygen therapy (HBOT) (60 min/session, 5 sessions/week at 2.5 ATA)

Biomarkers showed reduced blood glucose and elevated levels of urinary ketones with evidence of reduced metabolic activity (choline/N-acetylaspartate ratio) and normalized levels of insulin, triglycerides, and vitamin D

This is the first report of confirmed GBM treated with a modified SOC together with KMT and HBOT, and other targeted metabolic therapies

Glioblastoma multiforme (GBM) is the most common and malignant of the primary adult brain cancers

less than 20% of younger adults generally survive beyond 24 months

glucose and glutamine are the primary fuels that drive the rapid growth of most tumors including GBM

Glucose drives tumor growth through aerobic fermentation (Warburg effect), while glutamine drives tumor growth through glutaminolysis

The fermentation waste products of these molecules, i.e., lactic acid and succinic acid, respectively, acidify the tumor microenvironment thus contributing further to tumor progression

Glucose and glutamine metabolism is also responsible for the high antioxidant capacity of the tumor cells thus making them resistant to chemo- and radiotherapies

The reliance on glucose and glutamine for tumor cell malignancy comes largely from the documented defects in the number, structure, and function of mitochondria and mitochondrial-associated membranes

These abnormalities cause the neoplastic GBM cells to rely more heavily on substrate level phosphorylation than on oxidative phosphorylation for energy

dexamethasone not only increases blood glucose levels but also increases glutamine levels through its induction of glutamine synthetase activity

Calorie restriction and restricted KD are anti-angiogenic, anti-inflammatory, anti-invasive, and also kill tumor cells through a proapoptotic mechanism

Evidence also shows that therapeutic ketosis can act synergistically with several drugs and procedures to enhance cancer management improving both progression free and overall survival

hyperbaric oxygen therapy (HBOT) increases oxidative stress on tumor cells especially when used alongside therapies that reduce blood glucose and raise blood ketones

The glutamine dehydrogenase inhibitor, epigallocatechin gallate (EGCG) is also proposed to target glutamine metabolism

play a role during the initial chemotactic response of neutrophils shortly after infection

following vitamin C supplementation, a 20% increase in neutrophil chemotactic activity was observed

also contributes to the phagocytosis and killing of microbes by neutrophils

low levels of vitamin C occurring in high-stress situations

maturation, proliferation, and viability of T cells have all been shown to be upregulated by the presence of normal physiologic concentrations of vitamin C

Vitamin C has been shown to directly affect the number of Igs released from B cells

vitamin C among healthy young adult males showed a significant increase in serum levels of IgA, IgG, and IgM

effects of high-dose vitamin C on cytokine levels in cancer patients, finding decreased amounts of the cytokines Interleukin-1 alpha (IL-1 alpha), IL-2, IL-8, and tumor necrosis factor-alpha (TNF-alpha) after high-dose vitamin C infusion

when vitamin C was supplemented with vitamin E in healthy adults, it increased the production of cytokines IL-1 beta and TNF-alpha

vitamin C acts to modulate the levels of cytokines to prevent them from fluctuating in either direction

vitamin C also acts as an important antioxidant to the cells of the immune system.

human leukocytes, neutrophils, in particular, possess the ability to transport the oxidized form of vitamin C across its membrane to use as a defense mechanism against ROS produced during an immune response

Vitamin C also can recover other endogenous antioxidants in the body such as vitamin E and glutathione, returning them to their active state

vitamin C can decrease the activation of NF-kB

can reduce harmful nitrogen-based compounds such as N-nitrosamines and nitrosamides, both of which are carcinogenic 

subjects taking oral vitamin C supplementation saw a 60% to 90% reduction in oxidative stress compared to a placebo control

subjects infused with vitamin C alone had a 516% increase in glutathione levels compared to subjects not provided the 500 mg daily supplementation

hydroxylating proline and lysine

mature and stabilize the tissue of a healing wound

healing

oral surgery

improved soft tissue regeneration

vitamin C increases the mRNA levels of type I and type III collagen in the human dermis

Studies have demonstrated that those with low levels of vitamin C are at a significantly higher risk of respiratory infection compared to those with normal levels

viral cold duration was reduced by about 8% in adults and 13.5% in children using prophylactic daily doses of 200 mg of oral vitamin C

prophylactically supplementing vitamin C decreases the risk of infection with respiratory viruses such as the common cold

combined with probiotics, oral vitamin C supplementation showed a 33% decrease in the incidence of respiratory tract infections in preschool-age children [

high-dose oral supplementation of vitamin C managed to prevent or reduce symptoms if taken before or just after the onset of cold- or flu-like symptoms

improvements in oxygen saturation and decreased IL-6 levels (a marker of inflammation) in the treatment group compared to the control group

8 g doses of oral vitamin C

there is a negative correlation between age and serum levels of vitamin C

Patients with COVID-19 will likely also experience depletion in serum levels of vitamin C as a direct result of the upregulation of the immune system to combat the infection

Colunga et al. suggested that oral vitamin C can be combined with oral Quercetin, an antiviral flavonoid, to improve Quercetin’s ability to block viral membrane fusion of SARS-CoV-2

high doses of 1-2 g/day of oral vitamin C could prevent other upper respiratory infections

It appears vitamin C supplementation by itself does not provide a striking benefit in preventing COVID-19 infection for those without a deficiency

Hiedra et al. were able to show decreases in inflammatory biomarkers, such as D-dimer and ferritin

some evidence to support that prophylactic use of vitamin C helps reduce the severity of respiratory infection symptoms once a subject has already been infected

oral vitamin C in combination with zinc provided the largest amount of antibody titers 42 days

linear relationship between days of vitamin C therapy and survival duration

other studies were unable to find any definitive improvement concerning therapy with vitamin C

Fowler et al. aimed to see if a high-dose vitamin C infusion would benefit patients affected by ARDS, but they were unable to conclude that vitamin C infusion, compared to a placebo, could decrease vascular inflammation and damage in ARDS

in a sample of 67 COVID-19-positive ICU patients, 82% of them displayed plasma vitamin C levels below 0.4 mg/dL

continuous vitamin C infusion at a rate of 60 mg/kg/day for four days decreased the need for mechanical ventilation and vasopressor use but had no significant effect on overall mortality

Carr et al. suggested that high-dose IV vitamin C is most effective when treating sepsis as septic patients receiving the normal daily recommendations through diet still showed decreased vitamin C levels

High-dose IV vitamin C treatment has also been shown by Kakodkar et al. to decrease syndecan-1, an endothelial glycocalyx that contributes to mortality in septic patients

combined with hydrocortisone and thiamine, septic patients treated with 1.5 g of IV vitamin C every six hours showed a distinct decrease in their SOFA scores and none of the patients treated developed organ failure

combined with hydrocortisone and thiamine, septic patients treated with 1.5 g of IV vitamin C every six hours showed a distinct decrease in their SOFA scores and none of the patients treated developed organ failure

reduced overall mortality

reduced overall mortality

propose the use for high-dose vitamin C to aid in the treatment of septic shock-induced hypotension

treatment of severe sepsis using a high dose (up to 200 mg/kg/day) of IV vitamin C was explored in phase I, a double-blind, randomized, placebo-controlled trial by Fowler et al. [75]. Their findings included a reduction in SOFA scores and decreased vascular injury compared to a placebo control group, all while showing minimal adverse side effects

Maintaining a daily intake of 75 and 100 mg for men and women, respectively, as recommended by the U.S. Institute of Medicine

may result in part from the destruction of lymphocytes by the tumor and/or an impaired differentiation of lymphocytes progenitors

presence of liver metastasis (HR of, 2.27; P = .0003) and hypoalbuminemia were the 2 most powerful adverse prognostic factors

the properties and transcriptional signatures specific to CSC are highly predictive of overall patient survival pointing to their clinical relevance

CSCs represent a distinct population that can be prospectively isolated from the remainder of the tumor cells and can be shown to have clonal long-term repopulation and self-renewal capacity—the defining features of a CSC

whereas the expression of SVCT-2 is ubiquitous

differential sensitivity to VC may result from variations in VC flow into cells, which is dependent on SVCT-2 expression.

high-dose VC significantly impaired both the tumorspheres initiation (Fig. 4d, e) and the growth of established tumorspheres derived from HCC cells (Fig. 4f, g) in a time-dependent and dose-dependent manner.

Hepatocellular carcinoma (HCC)

The antioxidant, N-acetyl-L-cysteine (NAC), preventing VC-induced ROS production (a ROS scavenger), completely restored the viability and colony formation among VC-treated cells

DNA double-strand damage was found following VC treatment

DNA damage was prevented by NAC

Interestingly, the combination of VC and cisplatin was even more effective in reducing tumor growth and weight

Consistent with the in vitro results, stemness-related genes expressions in tumor xenograft were remarkably reduced after VC or VC+cisplatin treatment, whereas conventional cisplatin therapy alone led to the increase of CSCs

VC is one of the numerous common hepatoprotectants.

Interestingly, at extracellular concentrations greater than 1 mM, VC induces strong cytotoxicity to cancer cells including liver cancer cells

we hypothesized that intravenous VC might reduce the risk of recurrence in HCC patients after curative liver resection.

Intriguingly, the 5-year disease-free survival (DFS) for patients who received intravenous VC was 24%, as opposed to 15% for no intravenous VC-treated patients

Median DFS time for VC users was 25.2 vs. 18 months for VC non-users

intravenous VC use is linked to improved DFS in HCC patients.

In this study, based on the elevated expression of SVCT-2, which is responsible for VC uptake, in liver CSCs, we revealed that clinically achievable concentrations of VC preferentially eradicated liver CSCs in vitro and in vivo

Additionally, we found that intravenous VC reduced the risk of post-surgical HCC progression in a retrospective cohort study.

Three hundred thirty-nine participants (55.3%) received 2 g intravenous VC for 4 or more days after initial hepatectomy

As the key protein responsible for VC uptake in the liver, SVCT-2 played crucial roles in regulating the sensitivity to ascorbate-induced cytotoxicity

we also observed that SVCT-2 was highly expressed in human HCC samples and preferentially elevated in liver CSCs

SVCT-2 might serve as a potential CSC marker and therapeutic target in HCC

CSCs play critical roles in regulating tumor initiation, relapse, and chemoresistance

we revealed that VC treatment dramatically reduced the self-renewal ability, expression levels of CSC-associated genes, and percentages of CSCs in HCC, indicating that CSCs were more susceptible to VC-induced cell death

as a drug for eradicating CSCs, VC may represent a promising strategy for treatment of HCC, alone or particularly in combination with chemotherapeutic drugs

In HCC, we found that VC-generated ROS caused genotoxic stress (DNA damage) and metabolic stress (ATP depletion), which further activated the cyclin-dependent kinase inhibitor p21, leading to G2/M phase cell cycle arrest and caspase-dependent apoptosis in HCC cells

we demonstrated a synergistic effect of VC and chemotherapeutic drug cisplatin on killing HCC both in vitro and in vivo

Intravenous VC has also been reported to reduce chemotherapy-associated toxicity of carboplatin and paclitaxel in patients,38 but the specific mechanism needs further investigation

Our retrospective cohort study also showed that intravenous VC use (2 g) was related to the improved DFS in HCC patients after initial hepatectomy

several clinical trials of high-dose intravenous VC have been conducted in patients with advanced cancer and have revealed improved quality of life and prolonged OS

high-dose VC was not toxic to immune cells and major immune cell subpopulations in vivo

high recurrence rate and heterogeneity

tumor progression, metastasis, and chemotherapy-resistance

SVCT-2 was highly expressed in HCC samples in comparison to peri-tumor tissues

high expression (grade 2+/3+) of SVCT-2 was in agreement with poorer overall survival (OS) of HCC patients (Fig. 1c) and more aggressive tumor behavior

SVCT-2 is enriched in liver CSCs

these data suggest that SVCT-2 is preferentially expressed in liver CSCs and is required for the maintenance of liver CSCs.

pharmacologic concentrations of plasma VC higher than 0.3 mM are achievable only from i.v. administration

The viabilities of HCC cells were dramatically decreased after exposure to VC in dose-dependent manner

VC and cisplatin combination further caused cell apoptosis in tumor xenograft

These results verify that VC inhibits tumor growth in HCC PDX models and SVCT-2 expression level is associated with VC response

qPCR and IHC analysis demonstrated that expression levels of CSC-associated genes and percentages of CSCs in PDXs dramatically declined after VC treatment, confirming the inhibitory role of VC in liver CSCs

mitochondrial biogenesis may be a key driver of the CSC phenotype

Our results indicate that increased mitochondrial oxidative stress and high NADH levels are both key characteristics of the CSC metabolic phenotype

high levels of NAD(P)H auto-fluorescence are known to be a surrogate marker for mitochondrial “power”, high OXPHOS capacity and increased ATP production

CSCs may be strictly dependent on NAD(P)H to maintain their enhanced mitochondrial function

an intact NAD+ salvage pathway is strictly required for mammosphere formation, supporting our results using NAD(P)H auto-fluorescence, which enriched CSC activity by more than 5-fold.

Since glycolysis is especially critical for maintaining the TCA cycle, OXPHOS and overall mitochondrial function, we next assessed the effects of known glycolytic inhibitors

we show that two other natural products that function as effective glycolysis inhibitors, also inhibited mammosphere formation. More specifically, vitamin C (ascorbic acid), which induces oxidative stress and inhibits the activity of GAPDH (a key glycolytic enzyme) [17], also inhibited mammosphere formation, with an IC-50 of 1 mM (Figure 7B). Therefore, vitamin C was ~10 times more potent than 2-DG at targeting CSC propagation

silibinin (the major active constituent of silymarin, an extract of milk thistle seeds) [18], which specifically functions as an inhibitor of glucose uptake, blocked mammosphere formation, with an IC-50 between 200 and 400 µM

caffeic acid phenyl ester (CAPE), a key component of honey-bee propolis, has potent anti-cancer properties

Propolis has a strong history of medicinal use, dating back more than 2,000 years

Because of it aromatic ring structure (Figure 8), we speculated that CAPE might function as a potent inhibitor of oxidative mitochondrial metabolism

CAPE quantitatively inhibits the mitochondrial oxygen consumption rate (OCR) and, in turn, induces the onset of aerobic glycolysis (ECAR)

CAPE shows a clear selectivity for targeting CSCs and adherent cancer cells, relative to normal fibroblasts.

CAPE functions as a “natural” mitochondrial OXPHOS inhibitor, that preferentially targets the CSC sub-population. This could explain CAPE’s known anti-cancer properties

Our data directly shows that a small fraction of the total cell population, characterized by increased PGC1α activity, high mitochondrial ROS/H2O2 and high NADH levels, has the ability to survive and grow under anchorage-independent conditions, driving mammosphere formation

We highlight the utility of certain natural products, such as Silibinin, Vitamin C and CAPE, that could be used to therapeutically target CSCs. Silibinin is the major active component of silymarin, which is an extract prepared from milk thistle seeds.

high NADH is a property that is conserved between normal and cancerous stem cells

Previous studies have also shown that when non-CSCs and CSCs are both fed mitochondrial fuels (such as L-lactate or ketone bodies), that CSCs quantitatively produce more NADH in response to this stimulus

CSCs may be strictly dependent on NADH to maintain their enhanced mitochondrial function

The Noble Prize winner, Linus Pauling, was among the first to describe and clinically test the efficacy of Vitamin C, as a relatively non-toxic anti-cancer agent

Vitamin C has two mechanisms of action. First, it is a potent pro-oxidant, that actively depletes the reduced glutathione pool, leading to cellular oxidative stress and apoptosis in cancer cells. Moreover, it also behaves as an inhibitor of glycolysis, by targeting the activity of GAPDH, a key glycolytic enzyme.

Here, we show that Vitamin C can also be used to target the CSC population, as it is an inhibitor of energy metabolism that feeds into the mitochondrial TCA cycle and OXPHOS

Vitamin C may prove to be promising agent for new clinical trials, aimed at testing its ability to reduce CSC activity in cancer patients, as an add-on to more conventional therapies, to prevent tumor recurrence, further disease progression and metastasis

Interestingly, a breast cancer based clinical study has already shown that the use of Vitamin C, concurrent with or within 6 months of chemotherapy, significantly reduces both tumor recurrence and patient mortality

CAPE quantitatively reduces mitochondrial oxygen consumption (OCR), while inducing a reactive increase in glycolysis (ECAR). As such, it potently inhibits mammosphere formation with an IC-50 of ~2.5 µM. Similarly, it also significantly inhibits cell migration

we also demonstrate that 7 different inhibitors of key energetic pathways can be used to effectively block CSC propagation, including three natural products (silibinin, ascorbic acid and CAPE). Future studies will be necessary to test their potential for clinical benefit in cancer patients.

IR also indirectly induces DNA damage by stimulating reactive oxygen species (ROS) production

IR is known to induce EMT in vitro

p53 is activated in response to IR-induced DNA damage

IR paradoxically also promotes tumour recurrence and metastasis

DNA double-strand breaks (DSBs)

cancer cells undergoing EMT acquire invasive and metastatic properties

changes in the tumour microenvironment (TME)

IR seems to induce EMT and CSC phenotypes by regulating cellular metabolism

EMT, stemness, and oncogenic metabolism are known to be associated with resistance to radiotherapy and chemotherapy

Hanahan and Weinberg proposed ten hallmarks of cancer that alter cell physiology to enhance malignant growth: 1) sustained proliferation, 2) evasion of growth suppression, 3) cell death resistance, 4) replicative immortality, 5) evasion of immune destruction, 6) tumour-promoting inflammation, 7) activation of invasion and metastasis, 8) induction of angiogenesis, 9) genome instability, and 10) alteration of metabolism

EMT is a developmental process that plays critical roles in embryogenesis, wound healing, and organ fibrosis

IR is known to induce stemness and metabolic alterations in cancer cells

transforming growth factor-β [TGF-β], epidermal growth factor [EGF]) and their associated signalling proteins (Wnt, Notch, Hedgehog, nuclear-factor kappa B [NF-κB], extracellular signal-regulated kinase [ERK], and phosphatidylinositol 3-kinase [PI3K]/Akt

activate EMT-inducing transcription factors, including Snail/Slug, ZEB1/δEF1, ZEB2/SIP1, Twist1/2, and E12/E47

Loss of E-cadherin is considered a hallmark of EMT

IR has been shown to induce EMT to enhance the motility and invasiveness of several cancer cells, including those of breast, lung, and liver cancer, and glioma cells

IR may increase metastasis in both the primary tumour site and in normal tissues under some circumstance

sublethal doses of IR have been shown to enhance the migratory and invasive behaviours of glioma cells

ROS are known to play an important role in IR-induced EMT

High levels of ROS trigger cell death by causing irreversible damage to cellular components such as proteins, nucleic acids, and lipids, whereas low levels of ROS have been shown to promote tumour progression—including tumour growth, invasion, and metastasis

hypoxia-inducible factor-1 (HIF-1) is involved in IR-induced EMT

Treatment with the N-acetylcysteine (NAC), a general ROS scavenger, prevents IR-induced EMT, adhesive affinity, and invasion of breast cancer cells

Snail has been shown to play a crucial role in IR-induced EMT, migration, and invasion

IR activates the p38 MAPK pathway, which contributes to the induction of Snail expression to promote EMT and invasion

NF-κB signalling that promotes cell migration