Comparison of antiproliferative effects of 1-histamine-2 receptor antagonists, cimetidine, ranitidine, and famotidine, in gastric cancer cells

H2 antihistamines: May be useful for combination therapies in cancer?

Cancer morbimortality is still a great concern despite advances in research and therapies. Histamine and its receptors' ligands can modulate different biological responses according to the cell type and the receptor subtype involved. Besides the wide variety of histamine functions in normal tissues, diverse roles in the acquisition of hallmarks of cancer such as sustained proliferative signaling, resistance to cell death, angiogenesis, metastasis, altered immunity and modified microenvironment have been described. This review summarizes the present knowledge of the various roles of histamine H2 receptor (H2R) ligands in neoplasias. A bioinformatic analysis of human tumors showed dissimilar results in the expression of the H2R gene according to tumor type when comparing malignant versus normal tissues. As well, the relationship between patients' survival parameters and H2R gene expression levels also varied, signaling important divergences in the role of H2R in neoplastic progression in different cancer types. Revised experimental evidence showed multiple effects of H2R antihistamines on several of the cited hallmarks of cancer. Interventional and retrospective clinical studies evaluated different H2R antihistamines in cancer patients with two main adjuvant uses: improving antitumor efficacy (which includes regulation of immune response) and preventing toxic adverse effects produced by chemo or radiotherapy. While there is a long path to go, research on H2R antihistamines may provide new opportunities for developing more refined combination therapeutic strategies for certain cancer types to improve patients' survival and health-related quality of life.

Histamine receptors and cancer pharmacology: an update

In the present review, we will discuss the recent advances in the understanding of the role of histamine and histamine receptors in cancer biology. The controversial role of the histaminergic system in different neoplasias including gastric, colorectal, oesophageal, oral, pancreatic, liver, lung, skin, blood and breast cancers will be reviewed. The expression of histamine receptor subtypes, with special emphasis on the histamine H4 receptor, in different cell lines and human tumours, the signal transduction pathways and the associated biological responses as well as the in vivo treatment of experimental tumours with pharmacological ligands will be described. The presented evidence demonstrates that histamine regulates cancer-associated biological processes during cancer development in multiple cell types, including neoplastic cells and cells in the tumour micro-environment. The outcome will depend on tumour cell type, the level of expression of histamine receptors, signal transduction associated with these receptors, tumour micro-environment and histamine metabolism, reinforcing the complexity of cancer disease. Findings show the pivotal role of H4 receptors in the development and progression of many types of cancers, and considering its immunomodulatory properties, the H4 receptor appears to be the most promising molecular therapeutic target for cancer treatment within the histamine receptor family. Furthermore, the H4 receptor is differentially expressed in tumours compared with normal tissues, and in most cancer types in which data are available, H4 receptor expression is associated with clinicopathological characteristics, suggesting that H4 receptors might represent a novel cancer biomarker. LINKED ARTICLES: This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.

Immunomodulatory properties of cimetidine: Its therapeutic potentials for treatment of immune-related diseases

Histamine exerts potent modulatory impacts on the cells of innate- [including neutrophils, monocytes, macrophages, dendritic cells (DCs), natural killer (NK) cells and NKT cells] and adaptive immunity (such as Th1-, Th2-, Th17-, regulatory T-, CD8⁺ cytotoxic T cells, and B cells) through binding to histamine receptor 2 (H2R). Cimetidine, as an H2R antagonist, reverses the histamine-mediated immunosuppression, as it has powerful stimulatory effects on the effector functions of neutrophils, monocytes, macrophages, DCs, NK cells, NKT cells, Th1-, Th2-, Th17-, and CD8⁺ cytotoxic T cells. However, cimetidine reduces the regulatory/suppressor T cell-mediated immunosuppression. Experimentally, cimetidine potentiate some immunologic activities in vitro and in vivo. The therapeutic potentials of cimetidine as an immunomodulatory agent were also investigated in a number of human diseases (such as cancers, viral warts, allergic disorders, burn, and bone resorption) and vaccination. This review aimed to provide a concise summary regarding the impacts of cimetidine on the immune system and highlight the cellular mechanisms of action and the immunomodulatory effects of this drug in various diseases to give novel insights regarding the therapeutic potentials of this drug for treatment of immune-related disorders. The review encourages more investigations to consider the immunomodulatory characteristic of cimetidine for managing of immune-related disorders.

Repurposing drugs in oncology (ReDO)-cimetidine as an anti-cancer agent

Cimetidine, the first H₂ receptor antagonist in widespread clinical use, has anti-cancer properties that have been elucidated in a broad range of pre-clinical and clinical studies for a number of different cancer types. These data are summarised and discussed in relation to a number of distinct mechanisms of action. Based on the evidence presented, it is proposed that cimetidine would synergise with a range of other drugs, including existing chemotherapeutics, and that further exploration of the potential of cimetidine as an anti-cancer therapeutic is warranted. Furthermore, there is compelling evidence that cimetidine administration during the peri-operative period may provide a survival benefit in some cancers. A number of possible combinations with other drugs are discussed in the supplementary material accompanying this paper.

A review of stress-related mucosal disease

OBJECTIVE

To review and summarize the human and veterinary literature regarding stress-related mucosal disease (SRMD) pathogenesis, patient risk factors, and therapeutic options for prophylaxis and treatment.

ETIOLOGY

SRMD is a common sequela of critical illness in human patients. Development of SRMD results from splanchnic hypoperfusion, reperfusion injury, and exposure of the gastric mucosa to acid, pepsin, and bile acids following breakdown of the gastric mucosal defense system. Human patients with the highest risk of stress ulceration include those with respiratory failure necessitating mechanical ventilation greater than 48 h or coagulopathy. Currently, little is known about the incidence and pathophysiology of SRMD in critically ill veterinary patients.

DIAGNOSIS

A presumptive diagnosis can be made in high-risk patient populations following detection of occult or gross blood in nasogastric tube aspirates, hematemesis, or melena. Definitive diagnosis is achieved via esophagogastroduodenoscopy. Lesions are localized to the acid-producing portions of the stomach, the fundus, and body.

THERAPY

Therapy is aimed at optimization of tissue perfusion and oxygenation. Pharmacologic interventions are instituted to increase intraluminal pH and augment natural gastric defenses. Histamine(2)-receptor antagonists, proton pump inhibitors, and sucralfate are the mainstays of therapy. In people, clinically significant bleeding may necessitate additional interventions (eg, packed red blood cell transfusions, endoscopic, or surgical hemostasis).

PROGNOSIS

Mortality is increased in people with clinically significant bleeding compared to those patients who do not bleed. Institution of prophylaxis is recommended in high-risk patients. However, no consensus exists regarding initiation of prophylaxis, preference of frontline drug class, or indication for discontinuation of therapy. The prognosis of veterinary patients with SRMD remains unknown at this time.

Cimetidine inhibits epidermal growth factor-induced cell signaling

BACKGROUND

Cimetidine, a histamine-2 (H2) receptor antagonist, has been demonstrated to have anticancer effects on colorectal cancer, melanoma and renal cell carcinoma. In the current study, we clarified that cimetidine inhibits both epidermal growth factor (EGF)-induced cell proliferation and migration in hepatocellular carcinoma (HCC) cell lines.

METHOD

HCC cell lines (Hep3B, HLF, SK-Hep-1, JHH-2, PLC/PRF/5 and HLE) were used and cell proliferation was assessed by [3H]-thymidine incorporation assay. Cell migration was measured by in vitro cell migration assay. Biological effects of cimetidine were assessed with human EGF receptor (EGFR)-expressing mouse fibroblast cells (NR6-WT). The autophosphorylation of EGFR and the activation of other downstream effectors were analyzed by immunoprecipitation and immunoblotting. The concentration of intracellular cyclic AMP (cAMP) was measured by competitive enzyme immunoassay.

RESULTS

Cimetidine inhibited both EGF-induced cell proliferation and migration in Hep3B, HLF, SK-Hep-1 and JHH-2, while cimetidine did not affect EGF-induced cell proliferation and migration in PLC/PRF/5 and HLE. Cimetidine was revealed to disrupt the EGF-induced autophosphorylation of EGFR and its downstream effectors, mitogen activated protein kinases and phospholipase C-gamma. To define the molecular basis of this negative regulation, we identified that cimetidine significantly decreased intracellular cAMP levels and that decrement of cAMP inhibited autophosphorylation of EGFR. The cell permeable cAMP analog, CPT-cAMPS reversed the cimetidine-induced inhibition of EGF-induced cell proliferation and cell migration by restoring autophosphorylation of EGFR.

CONCLUSION

Cimetidine inhibited EGF-induced cell proliferation and migration in HCC cell lines by decreasing the concentration of intracellular cAMP levels. Cimetidine may be a candidate chemopreventive agent for HCC.

Expression of ets-1 transcription factor in human head and neck squamous cell carcinoma and effect of histamine on metastatic potential of invasive tumor through the regulation of expression of ets-1 and matrix metalloproteinase-3

BACKGROUND

Ets-1 controls the expression of critical genes involved in matrix remodeling. The matrix metalloproteinase-3 (MMP-3) and urokinase type plasminogen activator (uPA) are typical ets-1 responsive genes. Recent studies have shown an increase in histamine synthesis and content in various human neoplasias. We hypothesized that the increased local histamine overproduction contributed to activation of matrix remodeling through the activation of MMP-3 expression of peritumoral fibroblasts by means of ets-1 regulation in head and neck squamous cell carcinomas (HNSCCs).

METHODS

Paraffin-embedded sections of 30 HNSCCs were immunostained for ets-1. The presence of ets-1 and MMP-3 mRNA in tumor samples was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR). To simulate stromal reaction in vitro, cultured human mucosal fibroblast was used. The level of ets-1 and MMP-3 mRNA was compared by use of RT-PCR, as was their protein with flow-cytometry, in the presence or absence of basic fibroblast growth factor (bFGF) (10 ng/mL) and histamine (1 microM).

RESULTS

Correlation between ets-1 expression and clinicopathologic background was not significant. In all cases, expression of ets-1 was seen in the stroma. In in vitro study, histamine upregulates production of ets-1 and MMP-3 in cultured fibroblast, and bFGF can stimulate histamine expression in fibroblast. Immunofluorescence staining supported the results of RT-PCR and flow cytometry.

CONCLUSIONS

Ets-1 expression in HNSCCs has no prognostic value; however, ets-1 plays an important role in tumor-host interaction. Histamine may accelerate the spread of HNSCC through an ets-1-related mechanism.

Phenotypic profiling of engineered mouse melanomas with manipulated histamine production identifies histamine H2 receptor and rho-C as histamine-regulated melanoma progression markers

In the present study, the impact of acquired neoplastic L-histidine decarboxylase (HDC) expression, and its direct consequence, the release of histamine in the tumor environment, was assessed on melanoma tumor progression. B16-F10 mouse melanoma cells were manipulated via stable transfection, and nine novel transgenic variants were generated in triplicates, constitutively expressing the full-length sense mouse HDC mRNA, a mock control, and an antisense HDC RNA segment, respectively. Establishing both primary skin tumors and lung metastases in C57BL/6 mice, the nine variants with different histamine-releasing capacities were subjected to a comprehensive comparative progression profiling in vivo. Our analyses showed trends of markedly accelerated tumor growth (P < 0.001), and moderately increased metastatic colony-forming potential (P = 0.010) along with rising levels of local histamine production. Using RNase protection assay for screening of the melanoma progression profile, and Western blotting for subsequent result validation, we looked for molecular progression markers affected by melanoma histamine secretion. Investigation of 21 functionally clustered markers associated with tumor proliferation, angiogenesis, invasivity, metastasis formation, local or systemic immunomodulation, and histamine signaling revealed positive correlations between histamine production, tumor histamine H2 receptor and rho-C expression (P < 0.001, P = 0.002, respectively). These observations confirm the involvement of histamine in the molecular machinery of melanoma progression.

Effect of exogenous administration of transforming growth factor-beta and famotidine on the healing of duodenal ulcer under the impact of indomethacin

BACKGROUND

Non-steroidal anti-inflammatory drugs delay ulcer healing and cause refractory peptic ulcers in humans.

OBJECTIVE

To study the effects of growth factors on experimental duodenal ulcer healing in indomethacin-treated rats.

METHODS

Duodenal ulcers were induced in male Wistar rats by the serosal application of 75% acetic acid for 10 s. Rats were then treated with indomethacin (2 mg/kg/day; s.c.), transforming growth factor beta (15 ng locally injected subserosally at the ulcer site) or famotidine (5 mg/kg/day; p.o.), vehicle or combinations of treatments. On day 5, 8 or 12, rats were sacrificed and the ulcer area planimetrically measured under a dissecting microscope. Macroscopic area, microscopic diameter, collagen content and mucosal regeneration were assessed in histological preparations. Gastric secretion was assessed also in the pylorus-ligated rat-model. Data expressed as median and ranges were analyzed by non-parametric test.

RESULTS

Indomethacin delayed ulcer healing but transforming growth factor-beta and famotidine improved ulcer healing and reversed the effects of indomethacin. Maximal differences were observed on day 8. Transforming growth factor-beta was associated with an increase in epithelial and granulation tissue cell proliferation. Famotidine induced a profound inhibition of gastric secretion and increased collagen secretion but it did not affect cell proliferation.

CONCLUSIONS

Transforming growth factor-beta and famotidine accelerate ulcer healing delayed by indomethacin.

Autonomous histamine metabolism in human melanoma cells

Melanoma cells constitutively produce various cytokines as well as growth factors and express their corresponding receptors. Exogenous histamine is known to be a growth factor for some tumours while in other cases histamine inhibits tumour growth, and acts on G protein-coupled H1 and H2 histamine receptors. In previous studies we have detected the expression of the l-histidine decarboxylase (HDC) gene and the presence of HDC protein in human melanoma cell lines. In the present study, the activities of the histamine-forming enzyme HDC and of the degrading enzymes diamine oxidase (DAO) and histamine N-methyltransferase (HNMT) were measured in primary (WM35 and WM983) and metastatic (M1 and HT168) human melanoma cell lines. HDC activity was found in WM35 and WM983 cell lines, while detectable HNMT activity was measured in WM983, M1 and HT168 lines. In contrast, DAO showed very low activity in melanoma cell lines. Melanoma cells release a detectable amount of histamine into the medium without external stimuli. These findings support the possibility of autonomous histamine metabolism in melanoma cells. Our results suggest that not only exogenous histamine but also histamine produced and released by the melanoma cells and acting as an autocrine and paracrine factor may influence cell proliferation and modulate the in situ immune response of the host.

Cimetidine and a tamoxifen derivate reduce tumour formation in SCID mice xenotransplanted with a human melanoma cell line

Histamine is produced by many cells expressing histidine decarboxylase (HDC), the enzyme responsible for the synthesis of histamine. Since melanoma cells and tissue contain relatively large amounts of histamine, the functional significance of histamine was examined using specific antihistamines in vitro and in vivo in the human melanoma cell line HT168 and severe combined immunodeficiency (SCID) mice. It was shown that the H2 receptor antagonist cimetidine when combined with N, N-diethyl-2-[4-(phenylmethyl)phenoxy]-ethanamine-HCl (DPPE), a tamoxifen derivate, inhibits the proliferation of HT168 cells. Furthermore, it is suggested that there is a factor(s) that interferes with the exponential growth of HT168 cells xenografted to immunodeficient mice, and cimetidine and DPPE together significantly influence this factor(s). This combination of antihistamines also increases the survival of human melanoma-grafted mice. These changes are accompanied by enhanced infiltration of interferon-gamma- producing mouse macrophages into the tumour tissue. These findings suggest that two different mechanisms are probably acting concordantly: direct inhibition of tumour cell proliferation by the H2 receptor antagonists, and activation of the local immune response characterized by interferon-gamma production. These findings may help to elucidate the possibility of a rationally designed antihistamine strategy in melanoma therapy.

[Effect of exogenous administration of platelet-derived growth factor and epidermal growth factor on duodenal ulcer healing in rats treated with indomethacin]

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) delay peptic ulcer healing through mechanisms that are still not entirely understood. Growth factors play a significant role in healing.

AIM

To evaluate whether exogenous administration of platelet-derived growth factor (PDGF) reverses the effect of indomethacin in experimental duodenal ulcers in rats and to define the potential mechanisms involved in this process.

METHOD

Duodenal ulcer was induced in male Wistar rats with acetic acid. The rats were then administered indomethacin (2 mg/kg/day), PDGF-BB (30 ng/100 g/day), epidermal growth factor (EGF) (50 /kg/day) or famotidine (positive control) or the possible combinations of these. Macroscopic area, reduction in microscopic diameter, epithelial and granulation tissue proliferation, collagen secretion by granulation tissue, and gastric acid secretion were analyzed.

RESULTS

Indomethacin delayed duodenal ulcer healing by decreasing cellular proliferation and inhibiting collagen secretion. PDGF and EGF accelerated healing and reversed the effects of indomethacin. The mechanisms involved were associated with an increase in collagen proliferation and secretion without affecting gastric acid secretion. Famotidine also accelerated healing and reversed the effect of indomethacin, and these effects were associated with a marked inhibition of gastric acid secretion and increase in collagen secretion by granulation tissue.

CONCLUSIONS

Exogenous administration of PDGF and EGF accelerated healing and reversed the harmful effects of indomethacin in an experimental model of duodenal ulcer.

Defective angiogenesis in the inflammatory granulation tissue in histidine decarboxylase-deficient mice but not in mast cell-deficient mice

We have analyzed the role of histamine in the angiogenesis of the granulation tissue in histidine decarboxylase-deficient (HDC(-/-)) mice, mast cell-deficient mice (WBB6F1-W/W(V)), and their corresponding wild-type mice (HDC(+/+) and WBB6F(1)(+/+)). In HDC(+/+) mice, subcutaneous implantation of a cotton thread in the dorsum induced granulation tissue formation with angiogenesis, while the topical injection of anti-vascular endothelial growth factor (VEGF) IgG strongly suppressed them. In HDC(-/-) mice which showed lower VEGF levels in the granulation tissue, there was notably less angiogenesis and granulation tissue formation than in HDC(+/+) mice. The topical injection of histamine or the H(2) agonist dimaprit rescued the defective angiogenesis and granulation tissue formation in HDC(-/-) mice. There was no significant difference in the granulation tissue formation and angiogenesis between WBB6F1-W/W(V) and WBB6F1(+/+) mice. In addition, macrophages in the granulation tissue were found to express HDC. Our findings indicate that histamine derived from non-mast cells plays a significant role in the angiogenesis of the inflammatory granulation tissue.

A review of epidemiological studies on cancer in relation to the use of anti-ulcer drugs

H2-receptor antagonists have been widely used since the late 1970s for the treatment of gastrointestinal ulcers and other benign conditions of the stomach, oesophagus and duodenum. Several case reports suggested that long-term therapy with H2-receptor antagonists, mainly cimetidine and ranitidine, might increase the risk of gastric cancer. After early case reports, at least six analytical epidemiological studies (two cohort and four case-control) were published, including a total of about 1000 cases of gastric cancer. The relative risks (RR) were systematically and substantially elevated in the first year since starting H2-receptor antagonist use, and levelled off in the following years. Some excess risk was still apparent during the first 5 years of drug use, probably due to incorrect diagnosis and treatment of pre-existing neoplastic gastric lesions, but the estimated RR was not above unity for > or = 10 years since starting drug treatment in the two studies including information on long-term use. The findings of analytical epidemiological studies are thus consistent with the absence of a causal association between H2-receptor antagonist use and gastric cancer risk. Data on oesophageal and colorectal cancer do not support a relevant relation between cimetidine use and the risk of these neoplasms. With reference to total cancer mortality, in a Danish cohort study, for males the RR was 1.9 in the first year, and 1.4 in the first 5 years; corresponding values for females were 1.7 and 1.5. In a British cohort study, the RR was 3.4 in the first year, and 1.3 in the years 2-10. The excess risk in the first year was essentially due to gastric cancer. Post-marketing surveillance data for omeprazole and other proton pump inhibitors are much scantier than for H2-receptor antagonists, particularly on long-term use.

Enhancement by histamine of vascular endothelial growth factor production in granulation tissue via H(2) receptors

1. Roles of histamine in the production of vascular endothelial growth factor (VEGF) in the carrageenin-induced granulation tissue in rats were analysed in vitro and in vivo. 2. Incubation of the minced granulation tissue in the presence of histamine (1 and 10 microM) increased the content of VEGF protein in the conditioned medium in a time- and concentration-dependent manner. The levels of VEGF mRNA in the minced granulation tissue were also increased by histamine in a concentration-dependent manner. 3. The increase in the content of VEGF protein in the conditioned medium by histamine (10 microM) was suppressed by the H(2) receptor antagonist cimetidine (IC(50) 0.37 microM), but not by the H(1) receptor antagonist pyrilamine maleate, the H(3) receptor antagonist thioperamide or the cyclo-oxygenase inhibitor indomethacin. 4. The histamine-induced increase in the content of VEGF protein in the conditioned medium was inhibited by the cyclic AMP antagonist Rp-cAMP (IC(50) 6.8 microM), and the protein kinase A inhibitor H-89 (IC(50) 12.5 microM), but not by the protein kinase C inhibitors Ro 31-8425 and calphostin C or the tyrosine kinase inhibitor genistein. 5. Simultaneous injection of cimetidine (400 microg) and indomethacin (100 microg) into the air pouch of rats additively reduced the carrageenin-induced increase in VEGF protein levels and angiogenesis in the granulation tissue as assessed by using carmine dye. 6. These findings indicate that histamine has an activity to induce VEGF production in the granulation tissue via the H(2) receptor-cyclic AMP-protein kinase A pathway and augments angiogenesis in the granulation tissue.

Effect of cimetidine on intratumoral cytokine expression in an experimental tumor

To evaluate the immunomodulatory effects of histamine in vivo, we analyzed an experimental syngenic tumor model using a colon adenocarcinoma cell line, CT-26, in Balb/c mice. In this model, distinct tumor growth was observed around 6 days after inoculation. Daily administration of cimetidine (0.12 mg/kg/day) significantly suppressed the increases in tumor volume and weight. On day 6 and day 7, histidine decarboxylase (HDC) activity was markedly increased. To examine the alterations in the local immune system, the cytokine expressions in the tumor tissue were measured by ribonuclease protection assay. The cytokine expression levels such as lymphotoxin-beta, tumor necrosis factor-alpha, interferon-gamma, interleukin-10, and interleukin-15 were considerably lower in tissues on day 14 than those on day 6. These decreased expressions were all restored by cimetidine. These results indicated that the effects of cimetidine on tumor growth in this model might be mediated by restoration of the decreased local cytokine expression, which exerts antitumoral effects.

Nephrotoxicity and hepatotoxicity of histamine H2 receptor antagonists

The extensive use of selective histamine H2 receptor antagonists provides a unique opportunity to describe very rare adverse drug reactions. Although mild elevation of serum creatinine level following the administration of cimetidine is relatively common, acute interstitial nephritis (AIN) is a rare hypersensitivity reaction. There have been 25 published reports of AIN associated with H2 antagonist therapy and we also identified 16 cases from the Australian Adverse Drug Reaction Advisory Committee (ADRAC) database. AIN was reported most commonly following cimetidine administration. AIN was supported by renal biopsy in 28 patients and by rechallenge in 6. H2 antagonist-induced AIN was more commonly reported in men older than 50 years. In the majority of cases the onset was within 2 weeks of initiation of therapy (1 day to 11 months). The clinical manifestations were nonspecific including sterile pyuria, elevated erythrocyte sedimentation rate, fatigue, proteinuria and leucocytosis whereas rash, arthralgia and flank pain were rarely reported. There were 170 cases of hepatotoxicity following H2 antagonist administration reported to ADRAC. These were more common following ranitidine and included cholestatic, hepatocellular and mixed reactions. Hepatotoxicity was proven following liver biopsy in several cases published in the literature and in 15 cases reported to ADRAC. Hepatotoxicity recurred upon rechallenge in 6 cases. Generally, renal and hepatic adverse effects resolved quickly after cessation of H2 antagonist therapy and did not require specific treatment. Nephrotoxicity and hepatotoxicity following administration of an H2 antagonist is rare and a high index of suspicion is necessary for early detection. Now that many H2 antagonists are available over the counter, awareness of these conditions and early detection with cessation of H2 antagonist therapy would appear paramount.

Immunomodulation therapy in colorectal carcinoma

There has been much progress in the understanding of the relationship between the immune system and colorectal cancer. This has led to the use of immunomodulatory therapy in the adjuvant and palliative treatment of the condition. Although attempts at the use of non-specific immunomodulation with agents such as levamisole, cimetidine, alpha interferon and Bacillus Calmette-Guerin (BCG) have not produced significant clinical benefits when tested in randomized trials in both the adjuvant setting and for metastatic disease, promising results are being obtained with more specific therapy. Edrecolomab [corrected], a murine monoclonal antibody targeting the 17-1A antigen on malignant colorectal cells has produced a reduction in relapse and mortality rates when used as adjuvant treatment following surgery for Dukes' C colon cancer. Active specific therapy with autologous tumour vaccine administered with BCG has produced similar benefits in Dukes' B cancer. Both 3H1 anti-idiotypic antibody against carcinoembryonic antigen and 105AD7 antibody to gp72 glycoprotein have demonstrated in-vitro and in-vivo immune activation against tumour. Non-randomized studies postulate prolongation of survival using these antibodies in advanced disease. These agents are all currently being tested in randomized studies powered to detect meaningful survival differences and clinical benefit. Immune therapy offers the potential of low toxicity therapy in colorectal cancer and may have a role as an adjunct to conventional chemotherapy.