Archive

Archive for the ‘melanoma’ Category

Naltrexone for Cancer

Naltrexone is an opioid receptor antagonist approved and used for management of alcohol and opioid dependency.  Low dose naltrexone or LDN (at 1/10th of the dose used for drug rehab) however has been proposed as an off-label therapy for a broad range of immune disorders such as HIV, MS, autoimmune thyroiditis, and colitis, and is one of the more popular off-label treatments for cancer thanks to some promising trials, low toxicity, relative low cost and much internet publicity such as found on the Low Dose Naltrexone Homepage and a Low Dose Naltrexone Forum.  But if you don’t have a health science degree you might be wondering, what is the connection between cancer and opioids? And most importantly, does it work?

Opiates and Cancer

First some background on opioids and cancer.  Firstly, there is the difference of endogenous opiates (eg endorphins and enkephalins) vs. exogenous opiates (drugs).  The effects of opioids on cell growth is complex and is believed to be mediated through opioid and non-opioid receptor signalling (See Chen YL et al. The Other side of the Opioid Story: Modulation of Cell Growth and Survival Signalling, Curr Med Chem 2008:15(8):772-8), thus opioids directly modulate cell growth and endogenous opiates can directly suppress cancer growth.  On the other hand, exogenous opiates can suppress the immune system, which is not ideal for treating cancer. It has been known for some time from animal studies that opioids interfere with the immune system ( Sacerdote P, Opioids and the Immune System, Palliat Med 2006;20 Suppl 1:s9-15), and that opioid pain killers such as morphine can decrease and depress immunity.  In animal studies for example, morphine causes worsening of cancer, although the effect is different amongst different opioids, with buprenorphine (“Bupe”) perhaps the least immunosuppressive.

Background 1: Zagon

Now back to Naltrexone, an opioid antagonist.  There is no doubt that Dr. Ian Zagon at Penn State is a major pioneer researcher in endogenous opiates and the major bench-side explorer of “off-label” applications of LDN.  In his own words about the journey of discovery of opioid effects on cancer, he said : “When we discovered the effects of opioid antagonists such as naltrexone and naloxone in 1979, this was purely happenstance. Around 1975, we were interested in the effects of opiates… on children who were born to mothers that were addicted. The scientific literature revealed that these babies and children had neurological difficulties and were lower in body weight. We (myself and Dr. Patricia McLaughlin) developed a model to look at this in animals. Along the way, I was doing another project on neuroblastoma, a childhood tumor. When I found that these exogenous opioids altered growth of these developing animals… This started in 1977-1978. We then progressed to injecting cells into mice and creating cancers, and examined whether these exogenous opioids would repress growth of these cancers. In fact, they did…(as quoted on the LDN forum).

It turns out from Zagon’s research, that the central actor may be one “OGF” or opioid growth factor, or otherwise known technically as [Met5]-enkephalin.  Zagon proposed that OGF is an inhibitory peptide whose action is modulated via an OGF receptor and which modulates cancer cell proliferation and migration, and angiogenesis. Zagon has demonstrated that OGF inhibits pancreatic (BxPC-3), colon (HT-29), renal cell (Caki-2), neuroblastoma, and head and neck (CAL-27) cell lines (Int J Oncol, 2000 Nov;17(5):1053-61). Moreover, OGF also suppressed pancreas cancer in animals (Cancer Lett 1997 Jan 30;112(2):167-75) , and synergistically enhanced the efficacy of chemotherapy against pancreas cancer (Cancer Chemother Pharmacol 2005 Nov;56(5):510-20) and enhanced survival in squamous cell head and neck cancer as well(Cancer Chemother Pharmacol 2005 Jul;56(1):97-104).  Based on such observations, Zagon & McLaughlin filed a patent in 1997 claiming that the administration of an opiate antagonist such as Naltrexone “at an amount sufficient to effect the intermittent blockade of the zeta receptor present in the cancer (and surrounding tissues) thereby producing a subsequent period of elevated endogenous enkephalin levels or receptor numbers to inhibit, arrest and even prevent tumor growth” (US Patent 6136780)

Background 2. Bihari

Almost working in parallel as Zagon, but from the clinical side and not in the laboratory, there is one Dr. Bernard Bihari, who is an addiction specialist who used Naltrexone and claims to have discovered the immunomodulatory benefits of Naltrexone in 1985.   The story goes that Dr. Bihari began noticing in the 1980s that some of his addict patients with immune deficiency (subsequently discovered to be HIV/AIDS) had symptomatic improvement on lower doses of Naltrexone, so he conjectured that Naltrexone somehow upregulated their immune system (See AIDS Patient Care 1995 Feb;9(1):3).  Along this line of thinking and based on some reports that lymphoma responded to endorphin treatment in animals, he had treated a recurrent lymphoma patient with low dose naltrexone and the lymphoma got better.  He subsequently also treated a woman named CP with advanced melanoma and the cancer responded. Then from 1999 onwards, Dr. Bihari investigated the effects of LDN in private patients, using a low dose of 3mg given at night and theorizing that the treatment induced an increase in endorphins, especially metenkephalin, in the pre-dawn hours.  The endorphins would in turn directly suppress cancer growth and upregulate the immune system.  This theory coincided with Zagon’s animal work on how OGF may inhibit cancer and is consistent with the actions of naltrexone.  Unfortunately, there has not been any organized clinical trial or even published case series on this, except for what has been presented in the Low Dose Naltrexone website, that “as of March 2004 … medication by Dr. Bihari in some 450 patients with cancer, almost all of whom had failed to respond to standard treatments, suggests that more than 60% of patients with cancer may significantly benefit from LDN. Of the 354 patients with whom Dr. Bihari had regular follow-up, 86 have shown objective signs of significant tumor shrinkage, at least a 75% reduction. 125 patients have stabilized and/or are moving toward remission” Apparently,  of patients treated, “88 LDN-only group includes five breast cancer patients, one patient who had widespread metastatic renal cell carcinoma, three with Hodgkin’s disease and six with non-Hodgkin’s lymphoma. Reportedly, other cases, some on LDN for as long as four years, included a score of patients with non-small cell lung cancer, as well as patients with ovarian cancer, uterine cancer, pancreatic cancer (treated early), untreated prostate cancer, colon cancer, malignant melanoma, throat cancer, primary liver cancer, chronic lymphocytic leukemia, multiple myeloma and some others” according to another website.  Again reportedly, in June 2002 an oncologist and an oncology physician’s assistant from the National Cancer Institute reviewed some 30 charts of cancer patients at Dr. Bihari’s office, and about half were chosen as appearing to have responded to LDN without question.  Supposedly, copies of these records were sent to the NCI for further data collection on its part for consideration for NCI’s Best Case Series. Four cases of prostate cancers responding to LDN was reported as well in a patent “Method of Treating Cancer of the Prostate” Bihari filed in 2000. But again, regretfully, none of any of these cases ended up being published in the medical literature, and they circulate as quasi-anecdotal mentions online.

How might Naltrexone work in cancer?

In summary, based mainly on Zagon’s work, naltrexone at low dose administered nocturnally could bne postulated to work via 1) a stimulation of endogenous opiates as well as the number and density of opiate receptors on tumor cell membranes making them more responsive to the inhibitory effects of circulating opiates, which in turn suppresses tumor growth directly, 2) an enhancement of cellular immunity as a result of effects of higher levels of endogenous opiates, and 3) metabolites such as methylnaltrexone which exert antiangiogenic effects.

What does the medical literature say?

Bihari had published nothing on LDN and cancer in the medical literature.

Zagon had reported on using naltrexone in a mouse neuroblastoma model showing inhibition of growth and prolonged survival in those mice that develop tumors and protected some mice from developing tumors altogether (Brain Res 1989 Feb 20;480(1-2):16-28).  At a similar dose of 0.1mg/kg, his team was also able to retard implanted human colon cancer in mice (Cancer Lett 1996 Mar 29;101(2):159-64), apparently via an stimulation of metenkephalins, which is in line of his research hypothesis.

Clinically, only two single case reports of 1) a long surviving metastatic pancreas cancer treated with LDN and alpha-lipoic acid (Integr Cancer Ther 2006; 5(1):83-9), and 2) a B-cell lymphoma with clinical reversal using only LDN Integr Cancer Ther 2007; 6(3):293-296) can be found in the medical literature that I can find.

Along these lines, an OGF plus gemcitabine for pancreas cancer trial is on the way (starting this month!) at Penn State, but while there are several trials on LDN for Crohn’s and MS and other conditions on the way, there is nothing on the horizon testing LDN for cancer per se.

My Take

I have been prescribing off-label Naltrexone to my cancer patients for many years.  I remember being asked by organizers from Drs. Bihari’s camp to present at the 1st Annual LDN Conference in 2005 but declined to attend because I had no clear cut cases to report  (Then they asked me to report on the tolerability of the treatment, which is not meaningful, and I didn’t go).  Indeed, over the years, I have not seen any definitive responses that I can attribute to LDN with certainty.  I wish to give some credence to the cases of response found online, but such are anecdotes that cannot strictly be considered admissible evidence in clinical science, only suggestive leads for further investigations. There are inherent limitations for testing LDN of course: not every patient is a candidate (eg if on narcotics for cancer pain) for LDN and most who take it are on at least a few other treatment modalities making a judgement of LDN efficacy difficult.  Then also, the drug itself is cheap and generic and thus there is no industry interest in funding formal trials.  However, I still prescribe LDN to this day since the theoretical background is not unsound, the side-effects are minimal, and the substance is readily available and at such a reasonably low cost that I usually do not mind the addition of LDN to a patient’s treatment, especially if requested and especially in cases of pancreas or colon ca, melanoma, SCCHN where there has been studies or prostate cancer where there has been a patent filed.  Personally, I think LDN may perhaps have greater promise in other conditions such as Crohn’s and MS rather than cancer, and OGF may be a more direct opioid treatment option for cancer in the future.

Your comments welcome.

Advertisements

Disulfiram (Antabuse) for cancer

November 24, 2008 1 comment

Disulfiram (Antabuse) is an old thiocarbamate drug known to support the treatment of alcoholism and cocaine dependency. Unlike Naltrexone which is also used for alcoholism, its potential usefulness is cancer is well researched but curiously little publicized (Naltrexone is conversely little researched and well publicized ! Will discuss in this blog).  I am in fact quite impressed by the numerous documented investigations into Disulfiram’s use as an anti-cancer when I first investigated its potential in this area.

Schirmer and Scott seemed to have been the earliest to notice a relationship of disulfiram and tumor inhibition (Trans Am Assoc Genitourin Surg. 1966;58:63-6.), and subsequently Wattenberg was able to demonstrate that the dietary disulfiram inhibited DMH chemical induction of bowel cancer in mice  (JNCI, 1975 Apr;54(4):1005-6). Eventual research since the 70s have demontrated that disulfiram can block the P-glycoprotein extrusion pump and thus reduce drug-resistance, inhibits the transcription factor nuclear factor-kappaB, reduces angiogenesis, and inhibits tumor growth in cell lines and rodents.

Now where is the evidence?

a) In Vitro (cellular evidence):

Disulfiram inactivates the ability of the Rous sarcoma virus to malignantly transform chick embryo cells.

Disulfiram potentiated the cytotoxicity of nitrogen mustard and 5FU chemotherapy effects on leukemia and colorectal cells respectively.

Disulfiram can potentially reduce P-glycoprotein (P-gp) mediated drug resistance by inhibiting P-gp activity (possibly via cysteine modification) and/or by blocking its maturation (JNCI 2000 Jun 7;92(11):898-902).

Disulfiram induces apoptosis in melanoma cells (Mol Cancer Ther 2002 Jan;1(3):197-204).

Disulfiram inhibited invasion and angiogenesis of both tumor and endothelial cells possibly via interactions with MMP-2 and MMP-9 and inhibiting their proteolytic activity through a zinc related mechanism (Mol Pharmacol 2003 Nov;64(5):1076-84).

Disulfiram, as a member of the metal-chelating group of dithiocarbamate compounds, is able to bind with tumor cellular copper, forming an active complex with proteasome-inhibitory, apoptosis-inducing and anti-cancer activities. (Int J Mol Med 2007 Dec;20(6):919-25)

Disulfiram inhibited expression of metalloproteinases MMP-2 and MMP-9 and suppressed the invasion of human osteosarcoma cells. (J. Biochem Mol Biol 2007 Nov 30;40(6):1069-76)

b) In Vivo (animal evidence)

Dietary disulfiram inhibits chemical induction of intestinal (colon), bladder and breast cancer in rodents.

Disulfiram reduced ifosfamide-induced nephrotoxicity in rodents.

Disulfiram potentiated the cytotoxicity of nitrogen mustard chemotherapy in rodents (Cancer Res. 1989 Dec 1;49(23):6658-61).

c) Clinical (human experiences)

Roemeling et al. reported that human beings given 2 g of oral disulfiram at a particular time of day and high doses of cisplatin had lesser kidney toxicity. Disulfiram administration also apparently does not interfere with the antineoplastic activity of cisplatin (Chronobiol Intl 1986;3(1):55-64). Based on such evidence, a phase I and II study of cisplatinum and disulfiram was carried out which however overturned the hypothesis that disulfiram afforded nephroprotection in platinum chemotherapy (Am J Clin Oncol. 1990 Apr;13(2): 119 -24).

More recently in 2004, a first clinical report using a combination of oral zinc gluconate and disulfiram at approved doses for alcoholism induced >50% reduction in hepatic metastases and produced clinical remission in a patient with stage IV metastatic ocular melanoma, who has continued on oral zinc gluconate and disulfiram therapy for 53 continuous months with negligible side effects.

There is currently ongoing clinical trials of disulfiram with copper gluconate against liver cancer in Utah (ClinicalTrials.gov Identifier: NCT00742911) and of disulfiram as adjuvant against lung cancer in Israel (ClinicalTrials.gov Identifier: NCT00312819).

My take

This drug long known as a treatment for alcoholism found recent revival of interest as an anticancer and this has recently been reviewed by ZE Sauna et al. of the National Cancer Institute (Mol Biosyst 2005 Jul; 1(2): 127-34.  Epub 2005 May 26.)  Although there are no significant completed clinical trials to mention, both in vitro and animal data are supportive of its use, especially in melanoma and in conjunction with certain chemotherapies (eg 5FU), in cases of potential chemo-resistance, and as an anti-angiogenic perhaps in conjunction with Zinc gluconate.

It is not a totally hassle- free drug to prescribe though:

The initial dose is 500 mg for 1 to 2 weeks, followed by a maintenance dose of 250 mg (range 125 mg–500 mg) per day. The total daily dosage should not exceed 500 mg.  It is known to be a drug with moderate side-effects.  Of course, side-effects could be provoked if taken with alcohol, hence its use to support detox for alcohol dependence.  But other significant side-effects include hepatitis (1 case in 30,000 treated/yr), and neurologic. There are rare reports of psychosis and confusional states and peripheral nse effects, tiredness, headache and sleepiness are the most common.  Due to its CNS activity, drug-drug interaction is also an issue:

Drugs that may interact with disulfiram include, but are not limited to:

  • Bupropion (Wellbutrin IR/SR/XL, Amfebutamone)
  • Amphetamines (Adderall, Dexedrine, etc.)
  • Methylphenidate (Ritalin, Concerta, Focalin, etc.)
  • Cocaine (Occasionally used in dental procedures, and a known substance of abuse.)

The metabolism of other drugs may be inhibited by disulfiram, increasing their potential for toxic effects. Drugs known to have adverse effects when used concurrently with disulfiram include amitriptyline, isoniazid, and metronidazole (all with acute changes in mental state), phenytoin, some benzodiazepines, morphine, pethidine, and barbiturates.

Cimetidine for cancer

One of the commonest and cheapest of over-the-counter medicines, cimetidine (Tagamet®) is an anticancer?  This is one of the most surprising things to most of my patients, and I believe that many of my oncology colleagues don’t know this one either!

The following is the most comprehensive review of cimetidine use in cancer that one can currently find online.

Cimetidine, an H2-antagonist whose research and development as an stomach acid inhibitor for the treatment of peptic ulcers started its life in the early 60’s, and was approved and marketed from the 70’s as a treatment for heartburn and stomach ulcers. It went on to become the first drug to hit a billion US dollars per year sales and was a true block buster.  I still remember ordering it for patients with acute intestinal bleeding as an intravenous injection when I was training as a resident.

This is a particularly interesting drug from an off-label perspective, because it has been study for a large range of off-label uses, including for parathyroid storm, warts, herpes (shingles), weight loss, fibromyalgia, hives, HIV, conjunctival papillomatosis and irritable bowel syndrome.  There is also an accumulation of evidence suggesting that cimetidine enhances immune responsiveness (accounting at least in part for its potential use as an antiviral and for cancer).

Cimetidine for cancer?

Cimetidine’s possible anti-tumor action has been noticed as early as 1979 ( Also see below; Armitage JO and Sidney RD, Antitumor effect of cimetidine, Lancet 1(8121), pp. 882-3, 1979), the same year it was approved for use by the US FDA.  And reports of cimetidine’s immunomodulatory actions were soon after reported and it was about the same time that growth of colorectal cancer was reportedly retarded in vitro by cimetidine (JNCI, 67:6, pp. 1207-11, 1981). Since then, it has been demonstrated to possess anti-tumor activity against colon, gastric and kidney cancers, and melanomas. This activity involves a number of different mechanisms of action: a) it acts against metastases via inhibition of tumor cell adhesivenes; b) histamine acts as a growth factor in various tumor cell types via the activation of H2 receptors; and cimetidine antagonizes this effect as an anti-histamine; c) Cimetidine acts as an immunomodulator by enhancing the host’s immune response to tumor cells, via inhibition on T-cell suppressor activity; d) acts as an antiangiogenic.

a) In vitro (test tube) evidence:

Cimetidine and inhibit Caco-2 cancer cells in vitro, independently of the H2 receptor.

Cimetidine enhances the efficacy of 5 FU chemo on colon cancer SW620 cells.

Cimetidine was able to block the adhesion of gastric, esophageal and breast cancerto vascular endothelium via suppression of e-selectin (Gan To Kagaku Ryoho. 11, pp.1788-90, 2003. Japanese).

In vitro study on the effects of cimetidine on differentiation and antigen presenting capacity of monocyte-derived dendritic cells derived from advanced colorectal cancer patients suggest that cimetidine may enhance the host’s antitumour cell-mediated immunity by improving the suppressed dendritic cells function of advanced cancer patient (Br J Cancer 86:8, pp.1257-61, 2002).

b) In vitro (animal) evidence:

Suppresses VEGF and exerts antiangiogenic action on growth of colon cancer implants in mice (Tomita, K 2003; Natori T, 2005).

Tagamet added to chemo was superior in vivo when compared to chemo alone in extending survival of nude mice with human glioblastoma (Lefranc F et al. Int J Oncol 28:5, pp. 1021-1030, 2006)

Cimetidine diminished tumour proliferation in immunodeficient mice xenotransplanted with a human melanoma cell line.

Cimetidine antagonised the trophic effect of histamine on colorectal cancer cell lines in vivo and in vitro, possibly mediated via tumour histamine type 2 receptors

Cimetidine synergistically enhanced IL-2-induced NK and LAK cell activities in tumor-bearing rodents, and significantly prolonged their survival.

c) Clinical (human) evidence:

Armitage and Sidney first reported on possible anticancer effect of cimetidine in humans (Lancet, 1979) but they didn’t know why it would work.  They had two cases of cancer. One was a man with a head and neck cancer with presumed lung metastases but refused chemotherapy.  On cimetidine alone for tummy upsets, his metastases disappeared after two years.  The second case was a woman with metastatic lung cancer to the brain who was placed on cimetidine for heartburn and whose cancer grew smaller.

In 1982, four cases of metastatic melanoma responding to cimetidine alone was reported, and this was followed by a report from Sweden than cimetidine administered to six metastatic melanoma patients who were not responding to interferon alone resulted in complete remission in 2 and response/stability in another 2.  Subsequent reports on cancers of the oesophagus, stomach, liver, ovary, kidney and gallbladder treated with cimetidine noted improvement in 5 out of 7 cases.

Many investigative uses of cimetidine for cancer revolved around colorectal patients. Svendsen LB and colleagues from Denmark were one of the first to report on cimetidine as an adjuvant treatment in colon cancer where there seemed to be a survival benefit for those patients with Duke’s C disease but not for those who had disseminated disease (Dis Colon Rectum 38:5, pp. 514-8, 1995). An Australian team published in the same year a small trial of chemo plus cimetidine vs. chemo alone in metasatatic colon cancer and found a 36% CEA response in the cimetidine arm vs. 0% in the control (Eur J Clin Onc 21:5, pp/ 523-525, 1995). Four years later, the same team did a remarkable randomized controlled study showing that 800mg of cimetidine twice daily for only 5 days preoperatively appeared to have had a positive effect on colorectal cancer patient’s survival (Kelly MD et al. Cancer 85:8, pp.1658-1663, 1995). The best supportive evidence comes from Sumio Matsumoto of Japan. He conducted a clinical trial using 800mg / day of cimetidine for one year in patients with colorectal cases receiving 5-FU chemo after surgery (See Lancet 346, p.115, 1995, also Br J Cancer 86:1,  pp.162-167,2002).  His results were more positive than that reported by the Danish (see above) where at four and ten years, survival in the cimetidine treated patients was 96.3% and 84.6%, compared to 68.8% and 49.8% (p<0.0001) respectively. In patients with cancer of the rectum the results were even better: all of the cimetidine-treated patients were still alive at four years compared to only just over half of the controls.  The Japanese found that survival benefit was seen mainly with tumors expressing sialyl Lewis antigens X and A suggesting an immunomodulatory or cellular adhesion effect of cimetidine (Gan To Kagaku Ryoho. 11, pp.1788-90, 2003).  Another Japanese group recently examined the effect of cimetidine for recurrent colorectal cancer but found found no effect on survival, unless the recurrences was resected (Gan To Kagaku Ryoho 33:12, pp.1730-2, 2006).

Mixed results of efficacy were reported against renal cell cancer: Both American and Japanese reports mentioned complete response to cimetidine treatment alone (Am J Clin Oncol 15:2,pp.157-9, 1992; Nippon Hinyokika Gakkai Zasshi. 87:10, pp.201-4, 1996), and a Japanese study of combined interferon and cimetidine yielded a “definitively good” 40% response (J Urol 157:5,pp.1604-7, 1997), yet more recent trials yielded minimal responses (Am J Clin Oncol 21:5, pp.475-8, 1998).  Studies found no effect of cimetidine on gastric (Br J Cancer 81:9, pp.1356-62, 1999) or hormone refractory prostate cancers (Prostate 17:2, pp.95-9, 1990).

My take

Given its low toxicity and low cost, cimetidine can probably be administered to patients with colorectal cancer and possibly other adenocarcinomas that express the Sialyl Lewis antigens to minimize metastases and recurrence and enhance survival.  Enough supportive data also exist for routinely adding cimetidine in a cocktailed approach to melanoma and renal cell cancers patients. In more recent work, the demonstration that cimetidine may enhance dendritic cell function (See above) suggest that cimetidine should be routinely included in patients undergoing dendritic cell therapy.

Any downsides or concerns?

Generally not, but cimetidine does have occassional side-effects and the drug has a long list of potential interactions that one has to be careful about, and its use in cancer should be under the guidance of a professional.  I do have a concern for use of cimetidine in breast cancer because of its effect to increase serum prolactin which could stimulate breast cancer, although multiple epidemiologic studies have not demonstrated any higher incidence of breast (or other) cancers in cimetidine users (Cancer Epidemiol Biomarkers Prev 17:1, pp.67-72, 2008).

Why not more research?

The simple reason has to do with money and incentive in this capitalism-dominant world we live in.  The patent for cimetidine has long expired and it is a lowly over-the-counter drug these days and drug research (especially trials) is prohibitively expensive.  No drug company in its right mind would spare funds to study a drug they do not own just for the sake of benefitting mankind. It would be up to universities, government research centers, and other non-profits to pursue which is why the more recent studies are mostly from coutries (eg Japan, Scandanavia, China) with socialized healthcare systems and/or low cost to do trials and whose governments may be more interested in saving money ( read: looking for cheaper alternatives) to study this kind of “lowly” drug.  It is unfortunate but a reality in the world we live in.