Short summary

This research project addresses fundamental problems in the current treatment of patients with metastatic colorectal cancer (mCRC): a high percentage of patients with mCRC receiving chemotherapy do not benefit from the treatment due to inherited or acquired drug resistance, while they experience substantial side effects. Here, we propose to assess a repurposing strategy by introducing the drug disulfiram to patients with mCRC and drug resistant disease. 

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Rationale

A high percentage of patients with mCRC receiving chemotherapy do not benefit from the treatment due to inherited or acquired drug resistance, while they experience substantial side effects. The objective response rate to first-line systemic treatment of mCRC is approximately 50%, whereas only around 10-20% of mCRC patients will benefit from second-line chemotherapy, suggesting a high degree of cross-resistance among the drugs used. Here, we propose to assess a repurposing strategy by introducing the drug disulfiram to patients with mCRC and drug resistant disease. Disulfiram was first produced in 1881 and in 1945 the Danish researchers Hald and Jacobsen discovered that disulfiram causes very unpleasant effects in persons who had consumed alcohol. In the absence of alcohol the side effects of disulfiram are very modest and include drowsiness, headache, and a metallic/garlic taste in the mouth and even long-term disulfiram treatment does not cause severe adverse effects.

In the human organism, disulfiram is rapidly metabolized to dithiocarbamate that readily binds copper (Cu) thereby forming the active Cu(II)-diethyldithiocarbamate complex (CuEt). A search in Pubmed on disulfiram and cancer gives 355 hits. Without going into mechanistic details, disulfiram has been demonstrated to induce apoptosis, cause cell cycle arrest, inhibit invasion of cancer cells, and to enhance the effect of conventional chemotherapeutic drugs including killing of cancer stem cells and to reverse gemcitabine resistance in colorectal cancer cell lines. In a recent Nature paper, Bartek et al. describes in more details the molecular mechanisms of disulfiram plus copper effect on cancer cells. They show that the molecular target of disulfiram's anticancer effects is inhibition of NPL4, which is essential for turnover of proteins in cells. Besides blocking the enzyme acetaldehyde dehydrogenase, disulfiram targets drug efflux pumps, induces production of reactive oxygen species (ROS), activates the JNK and p38 MAPK signaling pathways, inhibits NFkB and inhibits the proteasome activity. All of these effects are well known anti-cancer drug effects. Furthermore, disulfiram mediated NFkB inhibition is known to enhance the cytotoxic anti-cancer effect of 5-FU and irinotecan in colorectal cancer cells, which further supports the described concept. In some experiments disulfiram alone has demonstrated anti-cancer activity. However, the consensus is that co-administration of divalent metal ions, especially copper, is required for the maximal anti-cancer effect of disulfiram to take place.
Disulfiram has also been tested on human cancer xenografts. In the Nature article, Bartek et al. showed significant tumor growth inhibition by administration of disulfiram and Cu-gluconate when treating mice xenografted with MDA-MB-231 tumors and an even more pronounced anti-tumor effect was obtained when treating with the active metabolite of disulfiram and Cu (CuET). However, there are no data on the clinical effects of disulfiram either alone or in combination with chemotherapy in patients with colorectal cancer and no studies on disulfiram in colorectal cancer can be found at www.clinicaltrials.org.

Using our drug screening platform "DEN50-R", which includes isogenic pairs of parental and drug resistant (acquired drug resistance) patient-derived cancer cell lines, we have recently shown that disulfiram plus copper given together induces cell death in colorectal cancer cells made resistant to irinotecan, which suggests that in a clinical setting, disulfiram plus copper can result in a reduction in tumor growth and tumor size with a potential impact on survival in mCRC patients who have failed conventional treatment for their disease. Even more importantly, when combining disulfiram and copper with irinotecan, an additive or synergistic growth inhibitory effect was observed with irinotecan resistant cell lines.

The overall purpose of this project is to conduct a Prospective Investigator Initiated Clinical Phase II Trial and test the efficacy of disulfiram (Antabuse) and copper to reverse irinotecan resistance in mCRC patients, who have progressed following a clinical benefit from irinotecan-containing treatment. Based on data from the literature and our own preclinical data, we have raised the hypothesis that disulfiram and copper treatment re-sensitizes irinotecan resistant colorectal cancer cells to treatment with irinotecan. Moreover, we hypothesize that predictive biomarkers for disulfiram plus copper treatment efficacy in cancer can be identified.

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Description of the cohort

Inclusion criteria:

•         Age ? 18 years.

•         Histologically verified colorectal adenocarcinoma.

•         Non-resectable mCRC.

•         Measurable or non-measurable disease according to RECIST version 1.1.

•         Performance status (WHO) of 0-1 and a life expectancy > 3 months

•         Documented progressive disease following at least 2 months of irinotecan (+/- fluoropyrimidines).

•         Adequate haematological function defined as neutrophils ? 1.5 x 109/l and platelets ? 100 x 109/l.

•         Adequate organ function (normal bilirubin, GFR (may be calculated) > 30 ml/min).

•         No toxicity > grade 2 after previous treatment except for neuropathy and alopecia

•         Woman of childbearing potential must have been tested negative in a serum pregnancy test within 5 days prior to randomisation. Male and female patients who have the potential to reproduce must agree to use a highly effective method of birth control. (i.e., pregnancy rate of less than 1 % per year) during the study and for 6 months after the discontinuation of study medication.

•         Willingness to refrain from alcohol consumption during the trial and 14 days after the last treatment with Disulfiram.

•         Has provided written informed consent prior to performance of any study procedure.

•       Written informed consent must be obtained according to the local Ethics Committee requirements.

Data and biological material

We planned to collect data from the patient's journal about diagnosis, histology, previous diagnoses, and treatments, medication, and CT/MR scans. Furthermore, we collect blood and a Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30). 

Collaborating researchers and departments

Department of Oncology, Odense University Hospital

• Dr. PhD, Line Schmidt Tarpgaard
• Prof. PhD, Per Pfeiffer

Department of Oncology, Rigshospitalet, Copenhagen, Denmark

• Dr. PhD, Camilla Qvortrup

Department of Oncology, Herlev and Gentofte Hospital, Denmark

• Dr. PhD, Rikke Løvendahl Eefsen
• Prof. PhD, Dorte Nielsen

Danish Cancer Society Research Center, Head: Genome Integrity Unit, Copenhagen, Denmark

• Prof., Jiri Bartek

Scandion Oncologu A/S, Stokholm, Sweden and Institute of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark

• Prof. Emeritus, Niels Brünner
• Ass. Prof., Jan Stenvang