The COC Protocol™ in Sarcoma
This document is a summary of the rationale and some of the current scientific evidence which supports the use of the COC Protocol medications alongside standard-of-care treatments for sarcoma. We understand that cancer is a very personal condition, and every patient has a unique set of challenges. For more information regarding your own personal situation please get in touch with the Care Oncology Clinic at +44 20 7580 3266 in the UK or 800-392-1353 in the United States, or visit the website at https://careoncology.com.
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The COC Protocol and sarcoma: Key points
- The COC Protocol is a combination of four commonly prescribed medications (atorvastatin, metformin, mebendazole, and doxycycline) with the potential to target sarcoma and help improve the effectiveness of standard anticancer therapies.
- Some types of sarcoma have a particularly high metabolic rate, potentially making them especially vulnerable to targeting with the COC Protocol.
- Cell and animal studies have found that metformin or statins can reduce the ability of sarcoma cells to take up and use energy, and block their ability to grow, divide, survive, and spread.
- Sarcoma cells grown in dishes also become more vulnerable to standard treatments in the presence of metformin or statins.
- In mice with sarcoma tumors, doxycycline in combination with another treatment reduced tumor growth and increased tumor cell death.
- In a small animal model of fibrosarcoma, tumors in animals treated with mebendazole had a more restricted blood supply compared to control animals.
- Data from human sarcoma studies is very limited. More clinical studies in sarcoma patients are needed.
The COC Protocol and sarcoma: Published evidence
The COC Protocol is a combination regime of four commonly prescribed medications, each with evidence of metabolically based anticancer activity and well understood safety profiles. These medications are metformin, atorvastatin, doxycycline, and mebendazole.
Sarcoma is a relatively rare type of cancer that affects soft tissue or bone and can develop anywhere in the body. A metabolically-targeted therapy like the COC Protocol aims to help weaken cancer cells by disrupting their ability to generate and use energy, and there is clear evidence that this strategy will work for sarcoma (Manara et al., 2013). This is in part because some types of sarcoma have a particularly high metabolic rate, potentially making them especially vulnerable to metabolic targeting strategies (Dasgupta et al., 2017; Issaq et al., 2014). Some of the studies which support the use of the COC Protocol as an adjunctive therapy alongside current standard treatments for sarcoma are presented below. Most of this evidence is still relatively early‑stage; using cells grown in dishes or in animal models of cancer. Some clinical studies in human patients are now underway.
You may notice that many of the studies below only focus on individual COC Protocol medications. We are the first to design an adjunct therapy which combines all four. We do believe that combining these medications will achieve the greatest results, and our own research program, called METRICS, is already producing more of the evidence needed to show this. You can read more about why we believe these medications work together so well to help target cancer, and about the METRICS program itself, in further sections below.
Metformin in sarcoma
Numerous laboratory studies show that the antidiabetic drug metformin can directly target and damage sarcoma cancer cells. These studies, carried out on cells grown in petri dishes or in small animal models of cancer, show that metformin either alone or in combination with other anti-metabolic treatments can actively work directly against sarcoma cells, reducing their ability to take up and use energy, and blocking their ability to grow, divide, survive, and spread.
Metformin is active against many different types of sarcoma cell, including osteosarcoma (Chen et al., 2015; Issaq et al., 2014; Ko et al., 2016), rhabdomyosarcoma (Garofalo et al., 2013; Issaq et al., 2014), chondrosarcoma (with or without IDH mutations) (Peterse et al., 2018), Ewing sarcoma (Dasgupta et al., 2017; Garofalo et al., 2013), and fibrosarcoma (Popović et al., 2017a). Evidence also shows that even the most resilient sarcoma cancer stem cells are vulnerable to metformin (Dasgupta et al., 2017; Quattrini et al., 2014; Xu et al., 2017).
Lab studies also show that metformin can improve the effectiveness of standard sarcoma treatments, and that sarcoma cells and sarcoma cancer stem cells grown in dishes are more easily killed by chemotherapy drugs in the presence of metformin (Dasgupta et al., 2017; Duo et al., 2013; Paiva-Oliveira et al., 2018; Quattrini et al., 2014; Shang et al., 2017). Small animal studies have also found that metformin is active against sarcoma tumors in the body (Ko et al., 2016; Popović et al., 2017a), although not all studies have reported this (Garofalo et al., 2013). Researchers suggest that that this discrepancy might in part be because solid tumors such as sarcoma can commonly have areas of low oxygen (called hypoxia), which might reduce the effectiveness of metformin in the body. However, it has been shown in the lab that metformin can remain effective against sarcoma cells even in conditions of low oxygen (Dasgupta et al., 2017). In addition, the COC Protocol combination is specifically designed to target cancer cells which are metabolizing energy as if they have a reduced supply of oxygen (i.e. the ‘Warburg effect’ (Vander Heiden et al., 2009)), and this is one reason why we believe the combinatorial effect of the Protocol is so important.
Based on the strength of laboratory studies, clinical trials investigating the effectiveness of metformin alongside other treatments in patients with sarcoma have now begun (Molenaar et al., 2017). A small Phase 1 trial which included patients with sarcoma who have already undergone a number of different treatments reported that a combination treatment which included metformin was well tolerated, with ‘modestly promising effects’ (Khawaja et al., 2016).
Statins in sarcoma
Statins have been around for many years and are still in regular use as a long-term treatment to help manage chronic cardiovascular conditions. This has helped researchers gather a large amount of data and begin to understand how statins might work in cancer.
A large number of studies using sarcoma cells grown in the lab show that statins, particularly fat-soluble ‘lipophilic’ statins like atorvastatin (Kato et al., 2010) can produce anticancer effects across numerous different types of sarcoma, including Ewing sarcoma, osteosarcoma, rhabdomyosarcoma, and fibrosarcoma.
At the cellular level, statins work by blocking the molecular processes sarcoma cells need to grow, divide, spread, and survive (Girnita et al., 2000; Sandoval-Usme et al., 2014; Wang et al., 1999). Statins can also encourage sarcoma cells to undergo a special type of programmed cell death, called apoptosis (Dimitroulakos et al., 2001; Fromigué et al., 2006; Kamel et al., 2017; Kany et al., 2018; Werner et al., 2004). In a rodent model of sarcoma, statins were shown to reduce tumor size and spread of the disease (Matar et al., 1998).
Importantly, studies also show that statins can help sensitize sarcoma cancer cells to standard anticancer treatments (Fromigué et al., 2008), and to reduce the cellular changes which can lead to chemotherapy resistance (Li et al., 2017). In lab studies using rhabdomyosarcoma cells, the chemotherapy drug doxorubicin’s ability to initiate apoptosis was enhanced by the presence of low concentrations of a statin (Werner et al., 2004). Further studies by the same group also showed that human rhabdomyosarcoma cells treated with statins took up more doxorubicin than those not treated with statins. They found this was because molecular pumps which cancer cells normally use to remove chemotherapy drugs were slowed, leading to more accumulation of the damaging chemotherapy drug and more damage to the cancer cell. This led the researchers to suggest that statins could help prevent drug resistance developing during normal treatment with standard chemotherapy (Werner et al., 2013). In another study, both stains and metformin were shown to reduce the ability of osteosarcoma and fibrosarcoma cells to survive in the lab, and to improve the effectiveness of chemotherapy drugs (Nilsson et al., 2011). In mice with sarcoma tumors, a statin helped to increase the antitumor activity of doxorubicin, while also helping to protect the heart from damage (a known occasional side-effect of doxorubicin) (Feleszko et al., 2000).
There are already numerous ongoing clinical trials investigating the effects of statins in cancer, however clinical studies specifically involving patients with sarcoma are only just beginning to get underway. An early dose-finding study has shown that even patients with very advanced sarcoma can tolerate statins as part of their treatment (López-Aguilar et al., 1999), and a case study has reported potentially promising effects of a combination of treatments including statins to help treat a young woman with treatment resistant rhabdomyosarcoma (Lindén et al., 2008). However, as yet no trials have directly investigated the anticancer effects of statins in sarcoma patients- clearly more clinical research is needed in this area, which we hope to address in part with our own METRICS study.
Mebendazole and sarcoma
Mebendazole, a member of the benzimidazole drug family, is widely and safely used to treat parasitic infections in both children and adults. Interest in mebendazole as a potential anticancer treatment is relatively new, and mostly based on promising mechanistic studies and compelling reports from case studies in cancer patients (Nygren and Larsson, 2014; Pantziarka et al., 2014). Mebendazole is thought to kill cancer cells partly by disrupting special structures inside the cell, called microtubules (Lai et al., 2017). There is also some evidence that mebendazole can help to ‘starve’ a tumor by blocking the growth of blood vessels the tumor needs to supply oxygen and nutrients (Pantziarka et al., 2014).
Based on this preliminary evidence, several clinical trials are now underway investigating mebendazole as an adjunctive treatment for cancer.
In sarcoma, a cell-based drug screen over 2000 different licensed drugs has flagged benzimidazoles as a potentially effective treatment for Ewing sarcoma (Pessetto et al., 2016) and other lab studies are starting to support this finding. A series of studies have shown that benzimidazole-like drugs can decrease the survival of chondrosarcoma cells in the lab (Li et al., 2011; Liu et al., 2012a, 2012b), and a recent conference report from a different group of researchers also found that mebendazole can reduce the ‘viability’ of rhabdomyosarcoma and Ewing sarcoma cells grown in the lab (Barber et al., 2018).
In an experimental hamster model of fibrosarcoma, animals treated with mebendazole had reduced tumor cell division, increased tumor cell death, and their tumors had more restricted blood supply compared to animals not treated with mebendazole (Popović et al., 2017b).
Doxycycline and sarcoma
Aside from being an effective tetracycline antibiotic, doxycycline also possesses other extremely valuable properties, including anti-inflammatory and anticancer activity (Bahrami et al., 2012). Lab studies and animal studies have long shown that doxycycline can block cancer cell growth, division, and movement (Duivenvoorden et al., 2002; Fife and Sledge, 1995, 1998).
In order to grow and spread, tumor cells must first cut through the structural matrix of molecules and proteins that surrounds them. They do this in part by producing enzymes called matrix metalloproteinases, or MMPs, which can chop through the surrounding matrix, helping the cancer cells to escape. High levels of some MMP molecules produced by cancer cells are sometimes associated with an increased chance of cancer spreading, and a worse outcome for the patient. For example, in osteosarcoma, a study on patient biopsies found that high levels of MMP2 compared to MMP9 were associated with a poorer response to chemotherapy (Kunz et al., 2016).
Doxycycline and other tetracyclines can block MMP production in sarcoma, and this is one way the drug is thought to work against cancer (Saikali and Singh, 2003). Studies using osteosarcoma cells grown in the lab show that doxycycline can block MMP production and reduce their ability to grow and divide (Cakir and Hahn, 1999; Roomi et al., 2014). In mice with human sarcoma tumors, doxycycline in combination with another treatment reduced tumor growth by over 30%, and increased levels of tumor cell death (Dickens and Cripe, 2003).
Clinical trials in patients with the slow-growing Kaposi’s sarcoma have shown that COL-3, a therapeutic molecule designed with a similar structure to tetracycline antibiotics like doxycycline can improve tumor burden in these patients (Cianfrocca et al., 2002; Richards et al., 2011). One study in patients with AIDS-related Kaposi’s sarcoma reported an overall response rate of 40%, along with a decrease in patient blood levels of MMPs (Dezube et al., 2006; Gonzalez-Avila et al., 2019). However, a different study in patients with other types of sarcoma did not report any beneficial effect of COL-3 alone (although it was well tolerated by patients) (Chu et al., 2007). We believe that for MMP inhibitors like doxycycline to reach their full potential, they must be given in combination, as part of a multi-targeted approach.
Other studies also show that doxycycline can stop cancer cells from repairing their DNA when it becomes damaged, for example, by chemotherapy (Peiris-Pagès et al., 2015). Indeed, studies have shown that doxycycline can help improve the effectiveness of chemotherapy activity against cancer cells grown in the lab (Foroodi et al., 2009; Lamb et al., 2015a). Emerging evidence also suggests that doxycycline can potently target cancer stem cells from a range of different cancers (Ozsvari et al., 2017; Zhang et al., 2017).
Doxycycline has just reached early clinical trials in cancer patients. Results from a first small study, published in October 2018, show that patients with early-stage breast cancer who took doxycycline for just 14 days before surgery reduced levels of molecular markers for presence of cancer stem cells by an average of around 40%. Beneficial effects were noted for all but one of the patients treated (8/9) (Scatena et al., 2018). Other clinical trials, including one investigating the effects of metformin and doxycycline in the treatment of some types of cancer, including uterine sarcoma, (trial no. NCT02874430) are now underway.
Our own evidence: The METRICS Study
What is METRICS?
METRICS is our own in-house research program. A great deal is already known about the safety and effectiveness of the COC Protocol medications in cancer. But it is also our responsibility to acknowledge that we don’t have all the answers, and that we still need to generate good quality clinical research investigating the COC Protocol in patients with cancer, to ensure the COC Protocol is as effective and safe as it can be.
To enable us to fund this research, we have developed a novel, affordable system where our clinical study, METRICS, is essentially ‘patient-funded’. Every consenting patient who enters the clinic is enrolled into METRICS, and these fees are helping to fund the study. This is a new model of clinical research, aimed at bridging the funding and data gaps which are currently hindering the repurposing and further clinical development of already licensed medications.
METRICS first results
In a first success for METRICS, results from our initial pilot study were recently published in the peer-reviewed scientific journal Frontiers in Pharmacology. The paper can be accessed freely online here.
The METRICS pilot study was an observational retrospective study, which means that our researchers looked back and analyzed patient clinical records to find out what happened. They collected data and recorded the outcomes from 95 patients with an advanced type of brain cancer called glioblastoma who attended the Care Oncology Clinic and who took the full COC Protocol alongside their usual standard treatments. This study did not have a control group, so our researchers compared the results from METRICS with previously published results from earlier studies in patients with the same type of cancer, and who also took standard-of-care treatments.
Initial results suggest that patients who attended our clinic and took the COC Protocol as part of their usual care were much more likely to survive at least 2 years (64.0% of patients in our study survived at least 2 years, compared to 27-29% for patients included in previously published studies), and tended to have longer survival times overall than would usually be expected for patients with this type of cancer (patients survived an average of 27 months in our study, compared to 15-16 months in earlier studies)(Agrawal et al., 2019).
These results are extremely promising, but they are also still preliminary. We don’t yet know exactly how the COC Protocol may have impacted survival times for example, or how other factors such as certain patient characteristics may have also influenced these results. But this first, initial evidence is certainly encouraging, and it suggests to us that we are heading in the right direction. Our next planned stage is to conduct a larger, well-designed study. You can find out more about future METRICS plans by looking online or contacting the clinic.
More about the COC Protocol
What is the COC Protocol?
The COC Protocol is a combination treatment regimen comprised of licensed medications, specifically designed by Care Oncology for adjunctive use alongside a patient’s usual treatments (i.e. standard-of-care).
The four medications included in the COC Protocol regimen are: metformin, a very common anti-diabetes drug; atorvastatin, a type of statin used to manage cardiovascular conditions; doxycycline, a type of antibiotic often used to treat chronic infections like acne; and mebendazole, a medicine commonly used to treat parasite infections in children and adults.
We chose these four medications from thousands of potential candidates specifically because they fit our predetermined selection criteria. These criteria include solid evidence of effectiveness against cancer, a coherent mechanism of action, and importantly, a good safety profile. These three central tenets have shaped our approach from the very beginning.
Safety is paramount
Cancer is a complex disease with complex treatments, and we believe that the addition of further therapies alongside standard treatments should be very carefully evaluated. Not just from the perspective of effectiveness, but also, importantly, in terms of safety. This is why our whole approach is based on evidence – mostly published scientific studies, and also, increasingly, our own data.
Many different medications on the market have at least some published evidence supporting their relatively effective use in cancer, but few of these medications have the level of evidence of both safety and effectiveness that we require for the COC Protocol. Large amounts of detailed data already exist for each of the protocol medications, garnered from years of use in the general population – and this helped to give us a crucial head-start during development.
We have painstakingly searched through decades of published data on each of the COC Protocol medications, exploring how they work in different patient populations (including patients with cancer), and on cell and animal models in the lab. These data, alongside our own clinical experience, help to ensure that we have a good understanding of how these medications will behave in patients with differing stages and types of cancer, both in combination with each other and also in combination with numerous other cancer therapies. This knowledge is paramount, and from our studies, this type of evidence is just not there yet for many other off‑label anticancer drug candidates – especially when given in combination.
An anti-metabolic therapy which can potentially target any cancer
The COC Protocol is designed to work by restricting the overall ability of cancer cells to take up and use (i.e. “metabolize”) energy.
Cancer cells need huge amounts of energy to survive, and the vast majority of cancers use an adaptive process called aerobic glycolysis to generate the excessive energy they need (Kroemer and Pouyssegur, 2008). Each of the medications in the protocol can target the various molecular metabolic processes involved in and surrounding aerobic glycolysis, and this can help lower the overall metabolic rate of the cancer cell (Jang et al., 2013).
We believe the COC Protocol medications can work in combination to consistently restrict energy supply and use, while simultaneously preventing cancer cells from adapting and using other pathways to take up energy (Jagust et al., 2019). As a result, cancer cells become increasingly weaker and less able to take in and use the nutrients (e.g. such as glucose and essential amino acids glutamine and arginine) they need from their surroundings (Andrzejewski et al., 2018; Liu et al., 2016). This makes it more difficult overall for cancer cells to survive, grow, and spread in the body. Gradually, the weakened cells (including more resilient and previously treatment- resistant cells) become more vulnerable to attack from other cell‑killing cancer therapies such as radiotherapy, chemotherapy, hormonal therapy, and targeted therapies (Bradford and Khan, 2013; Chen et al., 2012; Lacerda et al., 2014; Lamb et al., 2015a; Pantziarka et al., 2014).
By targeting the adapted metabolic mechanisms which are common to most cancers (but not usually healthy cells), we believe that the COC Protocol can be effective and selective for virtually any cancer regardless of specific type, stage, or location of cancer. Published epidemiological and lab studies increasingly support the potentially broad range of this type of therapy (Chae et al., 2015, 2016; Iliopoulos et al., 2011; Lamb et al., 2015b; Pantziarka et al., 2014).
Mechanistic coherence in action – the power of combination
The true power of the COC Protocol lies in the specific combination of medications we use. We developed the protocol not just as a regimen of four individual treatments each with anticancer activity, but also to work as a single combined treatment- with the potential to produce powerful synergistic effects (Mokhtari et al., 2017).
Each medication in the COC Protocol targets cancer cell metabolism in a distinct and complementary way, and we have termed this action ‘mechanistic coherence’. Put simply, mechanistic coherence describes how each medication can attack the cancer cell from a different angle. For example, cancer stem cells are a particularly resilient type of cancer cell, and each medication targets these cells in a different way: metformin targets the cell’s ‘batteries’ (called mitochondria) by making it very difficult for mitochondria to run the molecular reactions they need to produce energy, doxycycline blocks the cell-DNA machinery that mitochondria need to replicate and repair (Skoda et al., 2019), statins can alter cancer stem cell gene expression, making the cells more sensitive to other cancer therapies (Kodach et al., 2011), and mebendazole can interrupt numerous molecular processes involved in cell division to help block cancer stem cell growth (Hothi et al., 2012; Hou et al., 2015).
By combining all four agents together, the COC Protocol can hit cancer stem cells (and other cancer cells) across multiple ‘weak spots’, and like a one-two punch, this leaves the cells less able to dodge and recover.
Increasingly, evidence from lab studies are beginning to support the effectiveness of our own combinatorial approach. Mechanistic studies have shown that combining statin and metformin greatly decreases the growth of prostate and endometrial cancer cells more than either agent alone (Kim et al., 2019; Wang et al., 2017). And observational studies have also reported potentially ‘synergistic’ effects of these medications against various cancers (Babcook et al., 2014; Danzig et al., 2015; Lehman et al., 2012; Nimako et al., 2017). A clinical trial investigating metformin and doxycycline in breast cancer is now underway (NCT02874430), and our own research program, METRICS, is now also beginning to produce promising data.
A long-term adjunctive therapy
The COC Protocol is primarily designed to be a long-term ‘adjunctive’ therapy, to help optimize standard treatments. However, as metabolic treatment with the COC Protocol is intended to run long-term, patients may also take the protocol as a maintenance regime after standard treatment has been completed or during breaks from standard treatment and as part of a long-term strategy to mitigate the risk of recurrence or metastases. For this reason, it is also worth noting that each of the COC Protocol medications also has reported beneficial mechanisms of action in cancer which are not dependent on the co-administration of standard therapies, and which may independently help to reduce the risk of relapse and metastatic spread.
The Care Oncology model
Active medical supervision of each patient
Although the COC Protocol medications have been used safely in the general population for many years, they are not without side-effects. In addition, every patient’s situation is both complex, and unique- requiring careful, personalized assessment. This is why every patient who attends the Care Oncology Clinic is placed under the direct care of clinicians with specialist knowledge of prescribing the COC Protocol medications in the context of cancer. Our clinicians individually assess the potential benefits and risks involved in taking the COC Protocol with each patient. They will only recommend the COC Protocol to patients when they believe it will be safe and beneficial to do so. Each COC Protocol prescription is tailored to the needs of the patient, and doses and regimens are carefully reviewed and adjusted based on how the patient progresses.
It is therefore essential that patients are carefully monitored at our clinic throughout the course of their treatment.
Purpose of this article
This article is an overview of some of the scientific and medical published literature concerning the medications which comprise the patented Care Oncology protocol. Care has been taken to select relevant articles supporting the off-label use of these medicines in a clinical setting for the adjunct treatment of cancer. This article does not purport to be a comprehensive review of all the evidence, nor does it capture all the potential side-effects of such treatment.
This article is for information purposes only and it does NOT constitute medical advice. The medicines discussed herein are available on prescription-only and should not be taken without consultation with your doctor or other professional healthcare provider. Care Oncology doctors will discuss the suitability of these medicines with you and will liaise with your doctor or oncologist to discuss their suitability for you.
You must NOT rely on the information in this article as an alternative to medical advice from your doctor or other professional healthcare provider. If you have any specific questions about any medical matter you should consult your doctor or other professional healthcare provider. If you think you may be suffering from any medical condition you should seek immediate medical attention. You should never delay seeking medical advice, disregard medical advice, or discontinue medical treatment because of information contained in this article.
The copyright in this article is owned by Health Clinics Limited and its licensees.
The Care Oncology (“COC”) Protocol is protected by United States patent US9622982B2 and by various additional international patents.
Agrawal, S., Vamadevan, P., Mazibuko, N., Bannister, R., Swery, R., Wilson, S., and Edwards, S. (2019). A New Method for Ethical and Efficient Evidence Generation for Off-Label Medication Use in Oncology (A Case Study in Glioblastoma). Front. Pharmacol. 10.
Andrzejewski, S., Siegel, P.M., and St-Pierre, J. (2018). Metabolic Profiles Associated With Metformin Efficacy in Cancer. Front. Endocrinol. 9.
Babcook, M.A., Shukla, S., Fu, P., Vazquez, E.J., Puchowicz, M.A., Molter, J.P., Oak, C.Z., MacLennan, G.T., Flask, C.A., Lindner, D.J., et al. (2014). Synergistic Simvastatin and Metformin Combination Chemotherapy for Osseous Metastatic Castration-Resistant Prostate Cancer. Mol. Cancer Ther. 13, 2288–2302.
Bahrami, F., Morris, D.L., and Pourgholami, M.H. (2012). Tetracyclines: drugs with huge therapeutic potential. Mini Rev. Med. Chem. 12, 44–52.
Barber, J.D., Samizadeh, M., Jia, N., Siders, W., and Kaplan, J. (2018). Abstract 4801: Potential of mebendazole as an anti-tumor agent for adenoid cystic carcinoma and other rare cancers. Cancer Res. 78, 4801–4801.
Bradford, S.A., and Khan, A. (2013). Individualizing Chemotherapy using the Anti-Diabetic Drug, Metformin, as an Ã¢ÂÂAdjuvantÃ¢ÂÂ: An Exploratory Study. J. Cancer Sci. Ther. 5.
Cakir, Y., and Hahn, K.A. (1999). Direct action by doxycycline against canine osteosarcoma cell proliferation and collagenase (MMP-1) activity in vitro. Vivo Athens Greece 13, 327–331.
Chae, Y.K., Yousaf, M., Malecek, M.-K., Carneiro, B., Chandra, S., Kaplan, J., Kalyan, A., Sassano, A., Platanias, L.C., and Giles, F. (2015). Statins as anti-cancer therapy; Can we translate preclinical and epidemiologic data into clinical benefit? Discov. Med. 20, 413–427.
Chae, Y.K., Arya, A., Malecek, M.-K., Shin, D.S., Carneiro, B., Chandra, S., Kaplan, J., Kalyan, A., Altman, J.K., Platanias, L., et al. (2016). Repurposing metformin for cancer treatment: current clinical studies. Oncotarget 7, 40767–40780.
Chen, J., Lan, T., Hou, J., Zhang, J., An, Y., Tie, L., Pan, Y., Liu, J., and Li, X. (2012). Atorvastatin sensitizes human non-small cell lung carcinomas to carboplatin via suppression of AKT activation and upregulation of TIMP-1. Int. J. Biochem. Cell Biol. 44, 759–769.
Chen, X., Hu, C., Zhang, W., Shen, Y., Wang, J., Hu, F., and Yu, P. (2015). Metformin inhibits the proliferation, metastasis, and cancer stem-like sphere formation in osteosarcoma MG63 cells in vitro. Tumour Biol. J. Int. Soc. Oncodevelopmental Biol. Med. 36, 9873–9883.
Chu, Q.S.C., Forouzesh, B., Syed, S., Mita, M., Schwartz, G., Cooper, J., Copper, J., Curtright, J., and Rowinsky, E.K. (2007). A phase II and pharmacological study of the matrix metalloproteinase inhibitor (MMPI) COL-3 in patients with advanced soft tissue sarcomas. Invest. New Drugs 25, 359–367.
Cianfrocca, M., Cooley, T.P., Lee, J.Y., Rudek, M.A., Scadden, D.T., Ratner, L., Pluda, J.M., Figg, W.D., Krown, S.E., and Dezube, B.J. (2002). Matrix metalloproteinase inhibitor COL-3 in the treatment of AIDS-related Kaposi’s sarcoma: a phase I AIDS malignancy consortium study. J. Clin. Oncol. Off. J. Am. Soc. Clin. Oncol. 20, 153–159.
Danzig, M.R., Kotamarti, S., Ghandour, R.A., Rothberg, M.B., Dubow, B.P., Benson, M.C., Badani, K.K., and McKiernan, J.M. (2015). Synergism between metformin and statins in modifying the risk of biochemical recurrence following radical prostatectomy in men with diabetes. Prostate Cancer Prostatic Dis. 18, 63–68.
Dasgupta, A., Trucco, M., Rainusso, N., Bernardi, R.J., Shuck, R., Kurenbekova, L., Loeb, D.M., and Yustein, J.T. (2017). Metabolic modulation of Ewing sarcoma cells inhibits tumor growth and stem cell properties. Oncotarget 8, 77292–77308.
Dezube, B.J., Krown, S.E., Lee, J.Y., Bauer, K.S., and Aboulafia, D.M. (2006). Randomized phase II trial of matrix metalloproteinase inhibitor COL-3 in AIDS-related Kaposi’s sarcoma: an AIDS Malignancy Consortium Study. J. Clin. Oncol. Off. J. Am. Soc. Clin. Oncol. 24, 1389–1394.
Dickens, D.S., and Cripe, T.P. (2003). Effect of Combined Cyclooxygenase-2 and Matrix Metalloproteinase Inhibition on Human Sarcoma Xenografts. J. Pediatr. Hematol. Oncol. 25, 709.
Dimitroulakos, J., Ye, L.Y., Benzaquen, M., Moore, M.J., Kamel-Reid, S., Freedman, M.H., Yeger, H., and Penn, L.Z. (2001). Differential sensitivity of various pediatric cancers and squamous cell carcinomas to lovastatin-induced apoptosis: therapeutic implications. Clin. Cancer Res. Off. J. Am. Assoc. Cancer Res. 7, 158–167.
Duivenvoorden, W.C.M., Popović, S.V., Lhoták, S., Seidlitz, E., Hirte, H.W., Tozer, R.G., and Singh, G. (2002). Doxycycline decreases tumor burden in a bone metastasis model of human breast cancer. Cancer Res. 62, 1588–1591.
Duo, J., Ma, Y., Wang, G., Han, X., and Zhang, C. (2013). Metformin synergistically enhances antitumor activity of histone deacetylase inhibitor trichostatin a against osteosarcoma cell line. DNA Cell Biol. 32, 156–164.
Feleszko, W., Mlynarczuk, I., Balkowiec-Iskra, E.Z., Czajka, A., Switaj, T., Stoklosa, T., Giermasz, A., and Jakóbisiak, M. (2000). Lovastatin potentiates antitumor activity and attenuates cardiotoxicity of doxorubicin in three tumor models in mice. Clin. Cancer Res. Off. J. Am. Assoc. Cancer Res. 6, 2044–2052.
Fife, R.S., and Sledge, G.W. (1995). Effects of doxycycline on in vitro growth, migration, and gelatinase activity of breast carcinoma cells. J. Lab. Clin. Med. 125, 407–411.
Fife, R.S., and Sledge, G.W. (1998). Effects of doxycycline on cancer cells in vitro and in vivo. Adv. Dent. Res. 12, 94–96.
Foroodi, F., Duivenvoorden, W.C., and Singh, G. (2009). Interactions of doxycycline with chemotherapeutic agents in human breast adenocarcinoma MDA-MB-231 cells. Anticancer. Drugs 20, 115–122.
Fromigué, O., Haÿ, E., Modrowski, D., Bouvet, S., Jacquel, A., Auberger, P., and Marie, P.J. (2006). RhoA GTPase inactivation by statins induces osteosarcoma cell apoptosis by inhibiting p42/p44-MAPKs-Bcl-2 signaling independently of BMP-2 and cell differentiation. Cell Death Differ. 13, 1845–1856.
Fromigué, O., Hamidouche, Z., and Marie, P.J. (2008). Statin-induced inhibition of 3-hydroxy-3-methyl glutaryl coenzyme a reductase sensitizes human osteosarcoma cells to anticancer drugs. J. Pharmacol. Exp. Ther. 325, 595–600.
Garofalo, C., Capristo, M., Manara, M.C., Mancarella, C., Landuzzi, L., Belfiore, A., Lollini, P.-L., Picci, P., and Scotlandi, K. (2013). Metformin as an adjuvant drug against pediatric sarcomas: hypoxia limits therapeutic effects of the drug. PloS One 8, e83832.
Girnita, L., Wang, M., Xie, Y., Nilsson, G., Dricu, A., Wejde, J., and Larsson, O. (2000). Inhibition of N-linked glycosylation down-regulates insulin-like growth factor-1 receptor at the cell surface and kills Ewing’s sarcoma cells: therapeutic implications. Anticancer. Drug Des. 15, 67–72.
Gonzalez-Avila, G., Sommer, B., Mendoza-Posada, D.A., Ramos, C., Garcia-Hernandez, A.A., and Falfan-Valencia, R. (2019). Matrix metalloproteinases participation in the metastatic process and their diagnostic and therapeutic applications in cancer. Crit. Rev. Oncol. Hematol. 137, 57–83.
Hothi, P., Martins, T.J., Chen, L., Deleyrolle, L., Yoon, J.-G., Reynolds, B., and Foltz, G. (2012). High-Throughput Chemical Screens Identify Disulfiram as an Inhibitor of Human Glioblastoma Stem Cells. Oncotarget 3, 1124–1136.
Hou, Z.-J., Luo, X., Zhang, W., Peng, F., Cui, B., Wu, S.-J., Zheng, F.-M., Xu, J., Xu, L.-Z., Long, Z.-J., et al. (2015). Flubendazole, FDA-approved anthelmintic, targets breast cancer stem-like cells. Oncotarget 6, 6326–6340.
Iliopoulos, D., Hirsch, H.A., and Struhl, K. (2011). Metformin decreases the dose of chemotherapy for prolonging tumor remission in mouse xenografts involving multiple cancer cell types. Cancer Res. 71, 3196–3201.
Issaq, S.H., Teicher, B.A., and Monks, A. (2014). Bioenergetic properties of human sarcoma cells help define sensitivity to metabolic inhibitors. Cell Cycle Georget. Tex 13, 1152–1161.
Jagust, P., de Luxán-Delgado, B., Parejo-Alonso, B., and Sancho, P. (2019). Metabolism-Based Therapeutic Strategies Targeting Cancer Stem Cells. Front. Pharmacol. 10.
Jang, M., Kim, S.S., and Lee, J. (2013). Cancer cell metabolism: implications for therapeutic targets. Exp. Mol. Med. 45, e45.
Kamel, W.A., Sugihara, E., Nobusue, H., Yamaguchi-Iwai, S., Onishi, N., Maki, K., Fukuchi, Y., Matsuo, K., Muto, A., Saya, H., et al. (2017). Simvastatin-Induced Apoptosis in Osteosarcoma Cells: A Key Role of RhoA-AMPK/p38 MAPK Signaling in Antitumor Activity. Mol. Cancer Ther. 16, 182–192.
Kany, S., Woschek, M., Kneip, N., Sturm, R., Kalbitz, M., Hanschen, M., and Relja, B. (2018). Simvastatin exerts anticancer effects in osteosarcoma cell lines via geranylgeranylation and c-Jun activation. Int. J. Oncol. 52, 1285–1294.
Kato, S., Smalley, S., Sadarangani, A., Chen-Lin, K., Oliva, B., Brañes, J., Carvajal, J., Gejman, R., Owen, G.I., and Cuello, M. (2010). Lipophilic but not hydrophilic statins selectively induce cell death in gynaecological cancers expressing high levels of HMGCoA reductase. J. Cell. Mol. Med. 14, 1180–1193.
Khawaja, M.R., Nick, A.M., Madhusudanannair, V., Fu, S., Hong, D., McQuinn, L.M., Ng, C.S., Piha-Paul, S.A., Janku, F., Subbiah, V., et al. (2016). Phase I dose escalation study of temsirolimus in combination with metformin in patients with advanced/refractory cancers. Cancer Chemother. Pharmacol. 77, 973–977.
Kim, J.S., Turbov, J., Rosales, R., Thaete, L.G., and Rodriguez, G.C. (2019). Combination simvastatin and metformin synergistically inhibits endometrial cancer cell growth. Gynecol. Oncol. 0.
Ko, Y., Choi, A., Lee, M., and Lee, J.A. (2016). Metformin displays in vitro and in vivo antitumor effect against osteosarcoma. Korean J. Pediatr. 59, 374–380.
Kodach, L.L., Jacobs, R.J., Voorneveld, P.W., Wildenberg, M.E., Verspaget, H.W., van Wezel, T., Morreau, H., Hommes, D.W., Peppelenbosch, M.P., van den Brink, G.R., et al. (2011). Statins augment the chemosensitivity of colorectal cancer cells inducing epigenetic reprogramming and reducing colorectal cancer cell “stemness” via the bone morphogenetic protein pathway. Gut 60, 1544–1553.
Kroemer, G., and Pouyssegur, J. (2008). Tumor Cell Metabolism: Cancer’s Achilles’ Heel. Cancer Cell 13, 472–482.
Kunz, P., Sähr, H., Lehner, B., Fischer, C., Seebach, E., and Fellenberg, J. (2016). Elevated ratio of MMP2/MMP9 activity is associated with poor response to chemotherapy in osteosarcoma. BMC Cancer 16, 223.
Lacerda, L., Reddy, J.P., Liu, D., Larson, R., Li, L., Masuda, H., Brewer, T., Debeb, B.G., Xu, W., Hortobágyi, G.N., et al. (2014). Simvastatin radiosensitizes differentiated and stem-like breast cancer cell lines and is associated with improved local control in inflammatory breast cancer patients treated with postmastectomy radiation. Stem Cells Transl. Med. 3, 849–856.
Lai, S.R., Castello, S.A., Robinson, A.C., and Koehler, J.W. (2017). In vitro anti-tubulin effects of mebendazole and fenbendazole on canine glioma cells. Vet. Comp. Oncol. 15, 1445–1454.
Lamb, R., Fiorillo, M., Chadwick, A., Ozsvari, B., Reeves, K.J., Smith, D.L., Clarke, R.B., Howell, S.J., Cappello, A.R., Martinez-Outschoorn, U.E., et al. (2015a). Doxycycline down-regulates DNA-PK and radiosensitizes tumor initiating cells: Implications for more effective radiation therapy. Oncotarget 6, 14005–14025.
Lamb, R., Ozsvari, B., Lisanti, C.L., Tanowitz, H.B., Howell, A., Martinez-Outschoorn, U.E., Sotgia, F., and Lisanti, M.P. (2015b). Antibiotics that target mitochondria effectively eradicate cancer stem cells, across multiple tumor types: Treating cancer like an infectious disease. Oncotarget 6, 4569–4584.
Lehman, D.M., Lorenzo, C., Hernandez, J., and Wang, C. (2012). Statin Use as a Moderator of Metformin Effect on Risk for Prostate Cancer Among Type 2 Diabetic Patients. Diabetes Care 35, 1002–1007.
Li, T.-M., Lin, T.-Y., Hsu, S.-F., Wu, C.-M., Su, Y.-C., Kao, S.-T., Chang, C.-S., Fong, Y.-C., and Tang, C.-H. (2011). The novel benzimidazole derivative, MPTB, induces cell apoptosis in human chondrosarcoma cells. Mol. Carcinog. 50, 791–803.
Li, Y., Xian, M., Yang, B., Ying, M., and He, Q. (2017). Inhibition of KLF4 by Statins Reverses Adriamycin-Induced Metastasis and Cancer Stemness in Osteosarcoma Cells. Stem Cell Rep. 8, 1617–1629.
Lindén, O., Greiff, L., Wahlberg, P., Vinge, E., and Kjellén, E. (2008). Chemorefractory rhabdomyosarcoma treated with radiotherapy, bevacizumab, statins and surgery and maintenance with bevacizumab and chemotherapy. Onkologie 31, 391–393.
Liu, J.-F., Huang, Y.-L., Yang, W.-H., Chang, C.-S., and Tang, C.-H. (2012a). 1-benzyl-2-phenylbenzimidazole (BPB), a benzimidazole derivative, induces cell apoptosis in human chondrosarcoma through intrinsic and extrinsic pathways. Int. J. Mol. Sci. 13, 16472–16488.
Liu, J.-F., Chang, C.-S., Fong, Y.-C., Kuo, S.-C., and Tang, C.-H. (2012b). FPipTB, a benzimidazole derivative, induces chondrosarcoma cell apoptosis via endoplasmic reticulum stress and apoptosis signal-regulating kinase 1. Mol. Carcinog. 51, 315–326.
Liu, X., Romero, I.L., Litchfield, L.M., Lengyel, E., and Locasale, J.W. (2016). Metformin targets central carbon metabolism and reveals mitochondrial requirements in human cancers. Cell Metab. 24, 728–739.
López-Aguilar, E., Sepúlveda-Vildósola, A.C., Rivera-Márquez, H., Cerecedo-Diaz, F., Valdez-Sánchez, M., and Villasis-Keever, M.A. (1999). Security and Maximal Tolerated Doses of Fluvastatin In Pediatric Cancer Patients. Arch. Med. Res. 30, 128–131.
Manara, M.C., Garofalo, C., Ferrari, S., Belfiore, A., and Scotlandi, K. (2013). Designing novel therapies against sarcomas in the era of personalized medicine and economic crisis. Curr. Pharm. Des. 19, 5344–5361.
Matar, P., Rozados, V.R., Roggero, E.A., and Scharovsky, O.G. (1998). Lovastatin inhibits tumor growth and metastasis development of a rat fibrosarcoma. Cancer Biother. Radiopharm. 13, 387–393.
Mokhtari, R.B., Homayouni, T.S., Baluch, N., Morgatskaya, E., Kumar, S., Das, B., and Yeger, H. (2017). Combination therapy in combating cancer. Oncotarget 8, 38022–38043.
Molenaar, R.J., Coelen, R.J.S., Khurshed, M., Roos, E., Caan, M.W.A., van Linde, M.E., Kouwenhoven, M., Bramer, J.A.M., Bovée, J.V.M.G., Mathôt, R.A., et al. (2017). Study protocol of a phase IB/II clinical trial of metformin and chloroquine in patients with IDH1-mutated or IDH2-mutated solid tumours. BMJ Open 7, e014961.
Nilsson, S., Huelsenbeck, J., and Fritz, G. (2011). Mevalonate pathway inhibitors affect anticancer drug-induced cell death and DNA damage response of human sarcoma cells. Cancer Lett. 304, 60–69.
Nimako, G.K., Wintrob, Z.A.P., Sulik, D.A., Donato, J.L., and Ceacareanu, A.C. (2017). Synergistic Benefit of Statin and Metformin in Gastrointestinal Malignancies. J. Pharm. Pract. 30, 185–194.
Nygren, P., and Larsson, R. (2014). Drug repositioning from bench to bedside: Tumour remission by the antihelmintic drug mebendazole in refractory metastatic colon cancer. Acta Oncol. 53, 427–428.
Ozsvari, B., Sotgia, F., and Lisanti, M.P. (2017). A new mutation-independent approach to cancer therapy: Inhibiting oncogenic RAS and MYC, by targeting mitochondrial biogenesis. Aging 9, 2098–2116.
Paiva-Oliveira, D.I., Martins-Neves, S.R., Abrunhosa, A.J., Fontes-Ribeiro, C., and Gomes, C.M.F. (2018). Therapeutic potential of the metabolic modulator Metformin on osteosarcoma cancer stem-like cells. Cancer Chemother. Pharmacol. 81, 49–63.
Pantziarka, P., Bouche, G., Meheus, L., Sukhatme, V., and Sukhatme, V.P. (2014). Repurposing Drugs in Oncology (ReDO)—mebendazole as an anti-cancer agent. Ecancermedicalscience 8.
Peiris-Pagès, M., Sotgia, F., and Lisanti, M.P. (2015). Doxycycline and therapeutic targeting of the DNA damage response in cancer cells: old drug, new purpose. Oncoscience 2, 696–699.
Pessetto, Z.Y., Chen, B., Alturkmani, H., Hyter, S., Flynn, C.A., Baltezor, M., Ma, Y., Rosenthal, H.G., Neville, K.A., Weir, S.J., et al. (2016). In silico and in vitro drug screening identifies new therapeutic approaches for Ewing sarcoma. Oncotarget 8, 4079–4095.
Peterse, E.F.P., Niessen, B., Addie, R.D., de Jong, Y., Cleven, A.H.G., Kruisselbrink, A.B., van den Akker, B.E.W.M., Molenaar, R.J., Cleton-Jansen, A.-M., and Bovée, J.V.M.G. (2018). Targeting glutaminolysis in chondrosarcoma in context of the IDH1/2 mutation. Br. J. Cancer 118, 1074–1083.
Popović, D.J., Lalošević, D., Miljković, D., Popović, K.J., Čapo, I., and Popović, J.K. (2017a). Effect of metformin on fibrosarcoma in hamsters. Eur. Rev. Med. Pharmacol. Sci. 21, 5499–5505.
Popović, D.J., Lalošević, D., Popović, K.J., Čapo, I., Popović, J.K., and Miljković, D. (2017b). Effect of mebendazole on fibrosarcoma in hamsters. Trop. J. Pharm. Res. 16, 2445-2451–2451.
Quattrini, I., Conti, A., Pazzaglia, L., Novello, C., Ferrari, S., Picci, P., and Benassi, M.S. (2014). Metformin inhibits growth and sensitizes osteosarcoma cell lines to cisplatin through cell cycle modulation. Oncol. Rep. 31, 370–375.
Richards, C., Pantanowitz, L., and Dezube, B.J. (2011). Antimicrobial and non-antimicrobial tetracyclines in human cancer trials. Pharmacol. Res. 63, 151–156.
Roomi, M.W., Kalinovsky, T., Rath, M., and Niedzwiecki, A. (2014). In vitro modulation of MMP-2 and MMP-9 in pediatric human sarcoma cell lines by cytokines, inducers and inhibitors. Int. J. Oncol. 44, 27–34.
Saikali, Z., and Singh, G. (2003). Doxycycline and other tetracyclines in the treatment of bone metastasis. Anticancer. Drugs 14, 773–778.
Sandoval-Usme, M.C., Umaña-Pérez, A., Guerra, B., Hernández-Perera, O., Hernández-Perera, O., García-Castellano, J.M., Fernández-Pérez, L., and Sánchez-Gómez, M. (2014). Simvastatin impairs growth hormone-activated signal transducer and activator of transcription (STAT) signaling pathway in UMR-106 osteosarcoma cells. PloS One 9, e87769.
Scatena, C., Roncella, M., Di Paolo, A., Aretini, P., Menicagli, M., Fanelli, G., Marini, C., Mazzanti, C.M., Ghilli, M., Sotgia, F., et al. (2018). Doxycycline, an Inhibitor of Mitochondrial Biogenesis, Effectively Reduces Cancer Stem Cells (CSCs) in Early Breast Cancer Patients: A Clinical Pilot Study. Front. Oncol. 8.
Shang, D., Wu, J., Guo, L., Xu, Y., Liu, L., and Lu, J. (2017). Metformin increases sensitivity of osteosarcoma stem cells to cisplatin by inhibiting expression of PKM2. Int. J. Oncol. 50, 1848–1856.
Skoda, J., Borankova, K., Jansson, P.J., Huang, M.L.-H., Veselska, R., and Richardson, D.R. (2019). Pharmacological targeting of mitochondria in cancer stem cells: An ancient organelle at the crossroad of novel anti-cancer therapies. Pharmacol. Res. 139, 298–313.
Vander Heiden, M.G., Cantley, L.C., and Thompson, C.B. (2009). Understanding the Warburg Effect: The Metabolic Requirements of Cell Proliferation. Science 324, 1029–1033.
Wang, M., Xie, Y., Girnita, L., Nilsson, G., Dricu, A., Wejde, J., and Larsson, O. (1999). Regulatory role of mevalonate and N-linked glycosylation in proliferation and expression of the EWS/FLI-1 fusion protein in Ewing’s sarcoma cells. Exp. Cell Res. 246, 38–46.
Wang, Z.-S., Huang, H.-R., Zhang, L.-Y., Kim, S., He, Y., Li, D.-L., Farischon, C., Zhang, K., Zheng, X., Du, Z.-Y., et al. (2017). Mechanistic Study of Inhibitory Effects of Metformin and Atorvastatin in Combination on Prostate Cancer Cells in Vitro and in Vivo. Biol. Pharm. Bull. 40, 1247–1254.
Werner, M., Sacher, J., and Hohenegger, M. (2004). Mutual amplification of apoptosis by statin-induced mitochondrial stress and doxorubicin toxicity in human rhabdomyosarcoma cells. Br. J. Pharmacol. 143, 715–724.
Werner, M., Atil, B., Sieczkowski, E., Chiba, P., and Hohenegger, M. (2013). Simvastatin-induced compartmentalisation of doxorubicin sharpens up nuclear topoisomerase II inhibition in human rhabdomyosarcoma cells. Naunyn. Schmiedebergs Arch. Pharmacol. 386, 605–617.
Xu, H.Y., Fang, W., Huang, Z.W., Lu, J.C., Wang, Y.Q., Tang, Q.L., Song, G.H., Kang, Y., Zhu, X.J., Zou, C.Y., et al. (2017). Metformin reduces SATB2-mediated osteosarcoma stem cell-like phenotype and tumor growth via inhibition of N-cadherin/NF-kB signaling. Eur. Rev. Med. Pharmacol. Sci. 21, 4516–4528.
Zhang, L., Xu, L., Zhang, F., and Vlashi, E. (2017). Doxycycline inhibits the cancer stem cell phenotype and epithelial-to-mesenchymal transition in breast cancer. Cell Cycle Georget. Tex 16, 737–745.