IPSIndian Journal of Pharmacology
Home  IPS  Feedback Subscribe Top cited articles Login 
Users Online : 7585 
Small font sizeDefault font sizeIncrease font size
Navigate Here
Resource Links
 »  Similar in PUBMED
 »  Search Pubmed for
 »  Search in Google Scholar for
 »Related articles
 »  Article in PDF (626 KB)
 »  Citation Manager
 »  Access Statistics
 »  Reader Comments
 »  Email Alert *
 »  Add to My List *
* Registration required (free)

In This Article
 »  Abstract
 » Introduction
 » Monotherapy
 » Tetrathiomolybdate
 » D-Penicillamine
 » Trientine
 » Zinc
 » Disulfiram
 »  Overall Limitati...
 »  Combination Anti...
 »  Combination of T...
 »  Trientine in Com...
 »  Disulfiram in Co...
 »  D-penicillamine ...
 »  Zinc in Combinat...
 » Conclusion
 »  References
 »  Article Figures
 »  Article Tables

 Article Access Statistics
    PDF Downloaded71    
    Comments [Add]    

Recommend this journal


 Table of Contents    
Year : 2021  |  Volume : 53  |  Issue : 3  |  Page : 221-225

Copper-lowering agents as an adjuvant in chemotherapy

1 Department of Pharmaceutics, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Mumbai, Maharashtra, India
2 Department of Pharmacology, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Mumbai, Maharashtra, India

Date of Submission28-Apr-2020
Date of Decision05-Jan-2021
Date of Acceptance18-May-2021
Date of Web Publication22-Jun-2021

Correspondence Address:
Dr. Pramod Kadu
Department of Pharmaceutics, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai - 400 056, Maharashtra
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijp.IJP_68_20

Rights and Permissions

 » Abstract 

Copper is an important element essential for metabolism and normal human body function. Although it is an essential element, related imbalance leads to toxic effects. Studies have proved that there is an increase in copper level in cancer cells. Evidences suggest the link between increase in copper levels and progression of various types of cancers. Different strategies have been utilized to decrease the level of copper in various types of cancer cells. However, it was observed that cell machinery involved in copper homeostasis plays critical factor in lowering copper levels in cancer cells. The outcomes of many monotherapies consisting copper-lowering agents for the treatment of different types of cancers showed that the inhibition of single factor is not sufficient to inhibit the growth of cancer cells. The combination of copper-lowering agent with chemotherapeutic agent showed synergistic effect. Interestingly, the presence of copper-lowering agent in such combinations significantly improved the efficacy of chemotherapeutic agent. The present work has focused on the discussion of outcomes of studies involving anti-copper agent and chemotherapeutic agent and related future strategies.

Keywords: Adjuvant therapy, angiogenesis, chemotherapy, copper-chelating agents, copper in cancer cells

How to cite this article:
Kadu P, Sawant B, Kale PP, Prabhavalkar K. Copper-lowering agents as an adjuvant in chemotherapy. Indian J Pharmacol 2021;53:221-5

How to cite this URL:
Kadu P, Sawant B, Kale PP, Prabhavalkar K. Copper-lowering agents as an adjuvant in chemotherapy. Indian J Pharmacol [serial online] 2021 [cited 2023 Oct 2];53:221-5. Available from: https://www.ijp-online.com/text.asp?2021/53/3/221/318977

 » Introduction Top

Copper is one of the important trace elements. It is essential for lung elasticity, neuroendocrine function, neovascularization, adequate growth, metabolism, and cardiovascular integrity.[1] However, it has been observed that an imbalance in the copper levels is often related to several complications such as Wilson's disease.[2] The presence of higher copper levels in cancerous tissue assists in metastasis due to enhancement in angiogenesis and cell proliferation.[3] Copper is also responsible for causing cellular damage through alteration in the metabolic pathways, resulting in an increase of reactive oxygen species (ROS).[4] Hence, reducing the cellular copper levels for the treatment of different types of cancers is explored by many researchers. There are various methods available to measure the change in copper levels induced by copper-lowering drugs. One of the methods utilize serum ceruloplasmin (Cp) as an alternate measure is to determine the copper levels. The normal serum Cp levels in humans lie between 20 and 35 mg/dl, whereas the observed levels of Cp in cancer patients were 20–75 mg/dl. The reduction in copper levels (below normal) may cause clinical manifestations such as mild anemia, leukopenia, severe bone marrow depression, diarrhea, cardiac arrhythmias, peripheral neuropathy, and inhibition of epiphyseal bone growth in children. The major limitation in detecting copper levels is reduced levels of Cp below certain levels. It becomes an insensitive marker of copper levels below 5 mg/dl.[5] This clearly indicates that while developing strategies to reduce cellular copper levels to treat cancer the above factors should be taken into consideration [Figure 1].
Figure 1: Ceruplasmin levels in human (mg/dl)[5]

Click here to view

When anticopper drugs are used to treat cancer, the cell machinery which controls the copper homeostasis is a key factor responsible in the level of anticancer activity and related side effects. The outcomes of monotherapies involving copper-lowering agents for the treatment of various cancers are reviewed in the current article. Furthermore, cancer treatment strategies consisting of combination of anticancer drugs and copper-lowering agents are reviewed.

 » Monotherapy Top

Use of single anti-copper drug to treat cancer.

 » Tetrathiomolybdate Top

Brewer et al.[5] conducted first human trial of induction and maintenance of copper deficiency with tetrathiomolybdate (TM), as an antiangiogenic therapy for cancer. The rate of reduction of Cp levels was slow, but there were no significant side effects. The TM treatment was effective in early stage cancer but was ineffective in advanced cancer. TM treatment with meal resulted in nontoxic complex with copper, as it depletes from the body slowly. TM treatment before or after meal also resulted in lowering of copper levels. The study outcome indicated antiangiogenic effect with lowered copper levels which can be useful in the treatment of cancer.[6] TM showed antiangiogenic effect without producing toxicity in the patients having metastatic cancer.[5] In another clinical study involving patients with advanced kidney cancer, TM was given with meals. It was well tolerated and showed anticancer effects by lowering the copper levels.[7] Furthermore, the precise lowering of copper levels to the mid-range might has helped to meet the cellular requirements for the normal functioning and also to inhibit the angiogenic cytokine signalling. Antiangiogenic agents mostly target single angiogenic factor while there are dozens of proangiogenic factors. Hence, the inhibition of one angiogenic factor or its receptor is not sufficient because the tumors may utilize other factors.[8]

 » D-Penicillamine Top

The infiltrative growth of generally invasive 9 L gliosarcoma was inhibited by low copper diet and copper depletion by using D-Penicillamine (D-pen) in male Fischer rats.[9] The levels of serum copper elevated early and increased in proportion to tumor growth in wide range of tumors. There was normal level of serum copper in isolated tumor. It was also observed that the serum copper levels rise again after re-growth and extension of tumor.[10] The associated mechanism involves the generation of H2O2 and ROS when Cu (II) is reduced to Cu (I) by D-pen.[11] However, D-pen has limited intracellular delivery, high hydrophilicity, metal catalyzed oxidation, and rapid elimination.[12]

 » Trientine Top

Trientine was used as a substitute to pen in the case of patients who were intolerant to pen. Trientine promotes removal of copper from the body through urine. Mechanisms of action of trientine was as an antiangiogenic and apoptosis inducer when used as an anticancer agent.[13],[14],[15] Limitations of trientine therapy include worsening of neurological symptoms, lupus like reactions, reversible sideroblastic anemia, etc.[16]

 » Zinc Top

The inhibition of human prostatic carcinoma cell growth was caused by zinc possibly due to apoptosis and induction of cell cycle arrest.[17] Zinc inhibits copper absorption by its inductive effect on zinc–thionein synthesis.[18] There was high concentration of intracellular zinc in the prostate gland which diminished during the development of prostate cancer (PCa). The objective of the study was to understand the effect of zinc in cancer. The results of the study indicated that Zncl2 inhibited the proliferation of androgen receptor (AR) - retaining PCa cells. While the same effect was not observed in AR-deficient PCa cells. The expression of AR in transgenic adenocarcinoma mouse prostate-C2 and LNCaP cells was down regulated by zinc. It was depended on dose as well as time.[19] Pyrithione zinc (PYZ), is a complex of zinc, and functions as a metal ionophore and enhances the concentration of the intracellular zinc ion. PYZ was the most efficacious cytotoxic agent observed through analyzing inhibition of cell proliferation and induction of apoptosis in oral squamous cell carcinoma cells in vitro. Retaining the optimal ZN2+ concentration was important for cell survival as both increased and decreased ZN2+ levels-induced apoptosis in a variety of cell types.[20]

 » Disulfiram Top

Disulfiram (DSF) belongs to the dithiocarbamate family; it is a copper-binding agent and an inhibitor of aldehyde dehydrogenase. It is a well-known agent used in the treatment alcoholism. Copper containing MDA-MB-231 cells were treated with DSF which resulted in proteasome inhibition and apoptosis. DSF formed complex with copper. The DSF-copper complex showed proteasome inhibitory effect and apoptotic cell death in human breast cancer cells. However, the DSF-copper complex did not show proteasome inhibitory effect and apoptotic cell death in normal/immortalized cells.[21]

 » Overall Limitations of Monotherapy Top

Cancer cell growth is supported by many cellular factors. Furthermore, the coordination between these factors does exist. Because of the involvement of many proangiogenic factors and angiogenic inhibitors potentially interacting, angiogenesis has turned out to be potentially complex area. Hence, monotherapies targeting angiogenesis, as a single factor has not yielded the desired results. The outcomes of many monotherapies targeting only single cellular factor have emphasized that there is a need of inhibition of cancer cell growth by targeting multiple cellular factors.[8]

 » Combination Anticancer Therapy Top

Many strategies have been used to inhibit multiple cellular factors to treat cancer. There are studies which showed promising outcomes involving anticopper drugs and chemotherapeutic agents [Table 1].[3]
Table 1: Summary of combinations

Click here to view

 » Combination of Tetrathiomolybdate and Anticancer Drugs Top

Cisplatin is used for the treatment of various cancers.[33] However, it has limited therapeutic use because of side effects and increased resistance. It was observed that pretreatment of cells with elevated levels of copper reduced cisplatin uptake and enhanced resistance to cisplatin. The role of Ctrl and copper was examined using mouse model of human cervical cancer with the focus on cisplatin uptake and related response. TM with cisplatin showed synergistic antitumor effect. TM helped in increasing the concentration of cisplatin exclusively in tumor cells with simultaneous inhibition of tumor angiogenesis. Pretreatment of cultured human cervical and ovarian cancer cells with TM led to enhancement of cisplatin sensitivity and adducts in tumor cells. Further, TM was able to elevate cisplatin efficacy in highly metabolic tumors by reducing the bioavailable copper.[34] These promising evidences suggest the important role of TM co-administration with anticancer therapy to achieve synergism. TM also induced doxorubicin (dox) sensitivity in resistant tumor cell lines. The combination of TM and dox was found to be more effective at inducing apoptosis as compared to monotherapy.[22] TM increased sensitivity of ovarian cancer cells toward anticancer drugs dox, fenretinide, 5-fluorouracil, and mitomycin C. Furthermore, TM increased dox cytotoxicity along with modulation of key regulators of apoptosis. The well-known limitation for the use of dox is cardiac toxicity. It was reduced with the use of TM in preclinical assessments.[24] The hypothesis that TM inhibits the inflammatory process particularly at the activated-T-lymphocyte stage is well established.[22] Furthermore, targeting the mitogen-activated protein kinase (MAPK) pathway in melanoma by reducing Cu availability with the use of Cu chelators like TM and MAPK inhibitors (e.g., dabrafenib, encorafenib, vemurafenib, binimetinib, cobimetinib, and trametinib) might be a new strategy.[23] A pilot trial involving 24 patients with metastatic colorectal cancer (CRC) was conducted. Combination of TM with 5-flurouracil, leucovorin (IFL) and irinotecan was evaluated. TM inhibited angiogenesis. It was observed that the combination of IFL with TM was well tolerated along with maintenance of dose intensity of IFL. Overall, the use of TM can be considered safe with the combination chemotherapy used in the treatment of advanced CRC.[25]

 » Trientine in Combination with Anticancer Drugs Top

Trientine, a copper-lowering agent, was used in combination with carboplatin in the treatment of patients with advanced malignancies. Trientine helped in the enhancement of tolerance toward carboplatin treatment.[26] Trientine in combination with methotrexate inhibited angiogenesis with suppression of angiogenic factors in human colorectal carcinoma.[27]

 » Disulfiram in Combination with Anticancer Agents Top

There was reversal of bortezomib (BTZ) resistance and increase in related toxicity in MM cell line, when BTZ and DSF were used in combination. Inhibition of CuZnSOD activity by DSF was observed. It was observed that the upregulation of the enzymes CuZnSOD and H2O2 detoxifying enzyme glutathione peroxidase-1 was associated with BTZ resistance in MM cell lines.[35] DSF in combination with cisplatin and vinorelbine was assessed in a phase II b trial for the management of metastatic non-small cell lung cancer. It was well tolerated and prolonged the survival of the patients.[28] Human breast cancer cell lines MCF7/adr (multiply drug resistant), BT474 and MCF7/wt were used to study the effect of combinations of docetaxel and DSF. MTT assay was used for the measurement of Cytotoxic effect. Docetaxel, dox or epirubicin and DSF showed synergistic effect.[29] DSF enhances cytotoxic effects of cisplatin in five cell lines (e.g., A549, WI38, PC3, and MCF7) when given in combination. The enhanced cytotoxic action was found to be synergistic and might be due to their ability to induce an activating transcription factor 3 which is a regulator of cisplatin-induced cytotoxicity.[30]

 » D-penicillamine in Combination with other Anticancer Drugs Top

D-pen associated hydrophilicity, impermeability to the cell membrane and reactive thiol group are the challenges in terms of its delivery to cancer cells. It can be overcome by the formation of a conjugate of D-pen and poly-L-glutamic acid (PGA). Increase in cytotoxicity and intracellular ROS levels were observed in MDA-MB-468 (which is a human breast cancer cell line), HL-60, and murine leukemia cells (P388) treated with PGA-D-pen conjugate. The PGA-D-pen conjugation induces apoptosis. Furthermore, the conjugate effectively increased the survival of CD2F1 mice.[12] In another study, the combination of D-pen and idarubicin was found to enhance the therapeutic index by 2–3 fold higher than the monotherapy. The combination resulted in 89% tumor growth inhibition while it was only 60% with idarubicin. It was also observed that there was increase in the median survival of the mice model.[31]

 » Zinc in Combination with an Anticancer Drug Doxorubicin Top

Zinc oxide (ZnO) nanoparticles with dox penetrate more efficiently into drug sensitive as well as multidrug-resistant cancer cells in comparison to free dox. Furthermore, the combination ZnO/dox showed synergistic cytotoxic effects while monotherapy of Zno and dox failed show high cytotoxicity. ZnO prevented the formation of tumors by downregulation of CD 44.[32]

 » Conclusion Top

Anticancer therapies involving only copper-lowering agents or other anticancer monotherapies have limited therapeutic outcomes than their combinations. There are many reasons for this, but the major reason might be the inhibition of single factor. Hence, combination therapy involving copper-lowering agents with anticancer drugs could be an effective strategy as it targets multiple factors. Many copper-lowering agents and anticancer drugs showed synergistic effects. Copper-lowering agents have proved to enhance the properties of many anti-cancer drugs. However, copper homeostasis pathways play a very critical role which affects the efficacy of the anticancer drugs. Detection of copper levels is vital in patients undergoing anticancer therapy. This review will help in considering copper lowering agents as an adjuvant therapy with anticancer drugs. Hence, studies should be conducted to establish effective combination therapies involving copper-lowering agents and anticancer drugs with thorough consideration of copper homeostasis pathways.


The authors would like to thank the SVKM management for providing the necessary support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 » References Top

Osredkar J. Copper and zinc, biological role and significance of copper/zinc imbalance. J Clin Toxicol 2011;s3:1-8.   Back to cited text no. 1
Ferenci P. Pathophysiology and clinical features of Wilson disease. Metab Brain Dis 2004;19:229-39.   Back to cited text no. 2
Lowndes SA, Harris AL. The role of copper in tumour angiogenesis. J Mammary Gland Biol Neoplasia 2005;10:299-310.   Back to cited text no. 3
Gupte A, Mumper RJ. Elevated copper and oxidative stress in cancer cells as a target for cancer treatment. Cancer Treat Rev 2009;35:32-46.  Back to cited text no. 4
Brewer GJ, Dick RD, Grover DK, LeClaire V, Tseng M, Wicha M, et al. Treatment of metastatic cancer with tetrathiomolybdate, an anticopper, antiangiogenic agent: Phase I study. Clin Cancer Res 2000;6:1-10.   Back to cited text no. 5
Brewer GJ. The promise of copper lowering therapy with tetrathiomolybdate in the cure of cancer and in the treatment of inflammatory disease. J Trace Elem Med Biol 2014;28:372-8.   Back to cited text no. 6
Redman BG, Esper P, Pan Q, Dunn RL, Hussain HK, Chenevert T, et al. Phase II trial of tetrathiomolybdate in patients with advanced kidney cancer. Clin Cancer Res 2003;9:1666-72.   Back to cited text no. 7
Brewer GJ. Copper-lowering therapy with tetrathiomolybdate for cancer and diseases of fibrosis and inflammation. J Trace Elem Exp Med 2003;16:191-9.   Back to cited text no. 8
Brem S, Tsanaclis AM, Zagzag D. Anticopper treatment inhibits pseudopodial protrusion and the invasive spread of 9L gliosarcoma cells in the rat brain. Neurosurgery 1990;26:391-6.   Back to cited text no. 9
McCall JT, Goldstein NP, Smith LH. Implications of tract metals in human diseases. Fed Proc 1971;30:1011-5.   Back to cited text no. 10
Gupte A, Mumper RJ. An investigation into copper catalyzed D-penicillamine oxidation and subsequent hydrogen peroxide generation. J Inorg Biochem 2007;101:594-602.   Back to cited text no. 11
Wadhwa S, Mumper RJ. Intracellular delivery of the reactive oxygen species generating agent D-penicillamine upon conjugation to poly-L-glutamic acid. Mol Pharm 2010;7:854-62.   Back to cited text no. 12
Moriguchi M, Nakajima T, Kimura H, Watanabe T, Takashima H, Mitsumoto Y, et al. The copper chelator trientine has an antiangiogenic effect against hepatocellular carcinoma, possibly through inhibition of interleukin-8 production. Int J Cancer 2002;102:445-52.   Back to cited text no. 13
Kadowaki S, Endoh D, Okui T, Hayashi M. Trientine, a copper-chelating agent, induced apoptosis in murine fibrosarcoma cells by activation of the p38 MAPK pathway. J Vet Med Sci 2009;71:1541-4.   Back to cited text no. 14
Yoshii J, Yoshiji H, Kuriyama S, Ikenaka Y, Noguchi R, Okuda H, et al. The copper-chelating agent, trientine, suppresses tumor development and angiogenesis in the murine hepatocellular carcinoma cells. Int J Cancer 2001;94:768-73.   Back to cited text no. 15
European Association for Study of Liver. EASL clinical practice guidelines: Wilson's disease. J Hepatol 2012;56:671-85.   Back to cited text no. 16
Liang JY, Liu YY, Zou J, Franklin RB, Costello LC, Feng P. Inhibitory effect of zinc on human prostatic carcinoma cell growth. Prostate 1999;40:200-7.   Back to cited text no. 17
Hattori M. NII-electronic library service. Chem Pharm Bull 2002;27:2091.   Back to cited text no. 18
To PK, Do MH, Cho YS, Kwon SY, Kim MS, Jung C. Zinc inhibits expression of androgen receptor to suppress growth of prostate cancer cells. Int J Mol Sci 2018;19:3062.   Back to cited text no. 19
Srivastava G, Matta A, Fu G, Somasundaram RT, Datti A, Walfish PG, et al. Anticancer activity of pyrithione zinc in oral cancer cells identified in small molecule screens and xenograft model: Implications for oral cancer therapy. Mol Oncol 2015;9:1720-35.   Back to cited text no. 20
Chen D, Cui QC, Yang H, Dou QP. Disulfiram, a clinically used anti-alcoholism drug and copper-binding agent, induces apoptotic death in breast cancer cultures and xenografts via inhibition of the proteasome activity. Cancer Res 2006;66:10425-33.   Back to cited text no. 21
Hou G, Dick R, Abrams GD, Brewer GJ. Tetrathiomolybdate protects against cardiac damage by doxorubicin in mice. J Lab Clin Med 2005;146:299-303.   Back to cited text no. 22
Grimaldi AM, Simeone E, Festino L, Vanella V, Strudel M, Ascierto PA. MEK inhibitors in the treatment of metastatic melanoma and solid tumors. Am J Clin Dermatol 2017;18:745-54.   Back to cited text no. 23
Kim KK, Lange TS, Singh RK, Brard L, Moore RG. Tetrathiomolybdate sensitizes ovarian cancer cells to anticancer drugs doxorubicin, fenretinide, 5-fluorouracil and mitomycin C. BMC Cancer 2012;12:147.   Back to cited text no. 24
Gartner EM, Griffith KA, Pan Q, Brewer GJ, Henja GF, Merajver SD, et al. A pilot trial of the anti-angiogenic copper lowering agent tetrathiomolybdate in combination with irinotecan, 5-flurouracil, and leucovorin for metastatic colorectal cancer. Invest New Drugs 2009;27:159-65.   Back to cited text no. 25
Fu S, Hou MM, Wheler J, Hong D, Naing A, Tsimberidou A, et al. Exploratory study of carboplatin plus the copper-lowering agent trientine in patients with advanced malignancies. Invest New Drugs 2014;32:465-72.   Back to cited text no. 26
Yoshiji H, Yoshii J, Kuriyama S, Ikenaka Y, Noguchi R, Yanase K, et al. Combination of copper-chelating agent, trientine, and methotrexate attenuates colorectal carcinoma development and angiogenesis in mice. Oncol Rep 2005;14:213-8.   Back to cited text no. 27
Nechushtan H, Hamamreh Y, Nidal S, Gotfried M, Baron A, Shalev YI, et al. A phase IIb trial assessing the addition of disulfiram to chemotherapy for the treatment of metastatic non-small cell lung cancer. Oncologist 2015;20:366-7.   Back to cited text no. 28
Budman DR, Calabro A. In vitro search for synergy and antagonism: Evaluation of docetaxel combinations in breast cancer cell lines. Breast Cancer Res Treat 2002;74:41-6.   Back to cited text no. 29
O'Brien A, Barber JE, Reid S, Niknejad N, Dimitroulakos J. Enhancement of cisplatin cytotoxicity by disulfiram involves activating transcription factor 3. Anticancer Res 2012;32:2679-88.   Back to cited text no. 30
Wadhwa S, Mumper RJ. Polypeptide conjugates of D-penicillamine and idarubicin for anticancer therapy. J Control Release 2012;158:215-23.   Back to cited text no. 31
Wang J, Lee JS, Kim D, Zhu L. Exploration of zinc oxide nanoparticles as a multitarget and multifunctional anticancer nanomedicine. ACS Appl Mater Interfaces 2017;9:39971-84.   Back to cited text no. 32
Ishida S, Lee J, Thiele DJ, Herskowitz I. Uptake of the anticancer drug cisplatin mediated by the copper transporter Ctr1 in yeast and mammals. Proc Natl Acad Sci U S A 2002;99:14298-302.   Back to cited text no. 33
Ishida S, McCormick F, Smith-McCune K, Hanahan D. Enhancing tumor-specific uptake of the anticancer drug cisplatin with a copper chelator. Cancer Cell 2010;17:574-83.   Back to cited text no. 34
Salem K, McCormick ML, Wendlandt E, Zhan F, Goel A. Copper-zinc superoxide dismutase-mediated redox regulation of bortezomib resistance in multiple myeloma. Redox Biol 2015;4:23-33.  Back to cited text no. 35


  [Figure 1]

  [Table 1]


Print this article  Email this article


Site Map | Home | Contact Us | Feedback | Copyright and Disclaimer | Privacy Notice
Online since 20th July '04
Published by Wolters Kluwer - Medknow