Hepatic veno-occlusive disease caused by 6-thioguanine

Indol-3-Carbinol and Quercetin Ameliorate Chronic DSS-Induced Colitis in C57BL/6 Mice by AhR-Mediated Anti-Inflammatory Mechanisms

Inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis, are multifactorial inflammatory disorders of the gastrointestinal tract, characterised by abdominal cramps, bloody diarrhoea, and anaemia. Standard therapies, including corticosteroids or biologicals, often induce severe side effects, or patients may develop resistance to those therapies. Thus, new therapeutic options for IBD are urgently needed. This study investigates the therapeutic efficacy and safety of two plant-derived ligands of the aryl hydrocarbon receptor (AhR), quercetin (Q), and indol-3-carbinol (I3C), using a translationally relevant mouse model of IBD. Q and I3C are administered by gavage to C57BL/6 wild-type or C57BL/6 Ahr^-/- mice suffering from chronic colitis, induced by dextran sulphate sodium (DSS). The course of the disease, intestinal histopathological changes, and in-situ immunological phenotype are scored over 25 days. Our results show that both Q and I3C improved significantly clinical symptoms in moderate DSS colitis, which coincides with a significantly reduced histopathological score. Even in severe DSS colitis I3C, neither Q nor the therapy control 6-thioguanine (6-TG) can prevent a fatal outcome. Moreover, treatment with Q or I3C restored in part DSS-induced loss of epithelial integrity by induction of tight-junction proteins and reduced significantly gut inflammation, as demonstrated by colonoscopy, as well as by immunohistochemistry revealing lower numbers of neutrophils and macrophages. Moreover, the number of Th17 cells is significantly reduced, while the number of Treg cells is significantly increased by treatment with Q or I3C, as well as 6-TG. Q- or I3C-induced amelioration of colitis is not observed in Ahr^-/- mice suggesting the requirement of AhR ligation and signalling. Based on the results of this study, plant-derived non-toxic AhR agonists can be considered promising therapeutics in IBD therapy in humans. However, they may differ in terms of efficacy; therefore, it is indispensable to study the dose-response relationship of each individual AhR agonist also with regard to potential adverse effects, since they may also exert AhR-independent effects.

The recent advancement of low-dimensional nanostructured materials for drug delivery and drug sensing application: A brief review

In this review article, we have presented a detailed analysis of the recent advancement of quantum mechanical calculations in the applications of the low-dimensional nanomaterials (LDNs) into biomedical fields like biosensors and drug delivery systems development. Biosensors play an essential role for many communities, e.g. law enforcing agencies to sense illicit drugs, medical communities to remove overdosed medications from the human and animal body etc. Besides, drug delivery systems are theoretically being proposed for many years and experimentally found to deliver the drug to the targeted sites by reducing the harmful side effects significantly. In current COVID-19 pandemic, biosensors can play significant roles, e.g. to remove experimental drugs during the human trials if they show any unwanted adverse effect etc. where the drug delivery systems can be potentially applied to reduce the side effects. But before proceeding to these noble and expensive translational research works, advanced theoretical calculations can provide the possible outcomes with considerable accuracy. Hence in this review article, we have analyzed how theoretical calculations can be used to investigate LDNs as potential biosensor devices or drug delivery systems. We have also made a very brief discussion on the properties of biosensors or drug delivery systems which should be investigated for the biomedical applications and how to calculate them theoretically. Finally, we have made a detailed analysis of a large number of recently published research works where theoretical calculations were used to propose different LDNs for bio-sensing and drug delivery applications.

Therapeutic effect of N-acetylcysteine on chemotherapy-induced liver injury

BACKGROUND

N-acetylcysteine (NAC) may be useful in the management of chemotherapy-induced liver injury.

AIMS

The present study evaluates the possible therapeutic effects of NAC on chemotherapy-induced hepatotoxicity.

METHODS

A total of 102 patients' files who were diagnosed with cancer between 2015 and 2019 were evaluated retrospectively. Two patient groups with and without NAC were selected. NAC was administered in a 3-μg/kg IV dose in a 24-h infusion to 70 patients when any alanine aminotransferase (ALT) or gamma-glutamyl transferase (GGT) values reached three times the normal levels. The other group consisted of 32 patients who were not treated with NAC. Alanine aminotransferase and GGT values were recorded at pretreatment, and on the 1st, 3rd, 5th, and 7th days in both the NAC and non-NAC groups from files.

RESULTS

In the NAC group, ALT and GGT values on day 1, 3, 5, and 7 differed from each other, decreasing from day 1 to day 7. A statistically significant difference was noted between the values in the NAC group (p < 0.001). In the non-NAC group, the ALT values on day 7 were lower than the ALT values on day 1. A comparison of the ALT and GGT values in the NAC and non-NAC groups found that the values in the NAC group decreased earlier than in the non-NAC group.

CONCLUSIONS

This study shows that NAC has a therapeutic effect on hepatotoxicity in children being treated with chemotherapeutic agents due to underlying malign diseases. The early reduction in the results of liver function tests is important for the continuation of chemotherapy.

Predict New Therapeutic Drugs for Hepatocellular Carcinoma Based on Gene Mutation and Expression

Hepatocellular carcinoma (HCC) is the fourth most common primary liver tumor and is an important medical problem worldwide. However, the use of current therapies for HCC is no possible to be cured, and despite numerous attempts and clinical trials, there are not so many approved targeted treatments for HCC. So, it is necessary to identify additional treatment strategies to prevent the growth of HCC tumors. We are looking for a systematic drug repositioning bioinformatics method to identify new drug candidates for the treatment of HCC, which considers not only aberrant genomic information, but also the changes of transcriptional landscapes. First, we screen the collection of HCC feature genes, i.e., kernel genes, which frequently mutated in most samples of HCC based on human mutation data. Then, the gene expression data of HCC in TCGA are combined to classify the kernel genes of HCC. Finally, the therapeutic score (TS) of each drug is calculated based on the kolmogorov-smirnov statistical method. Using this strategy, we identify five drugs that associated with HCC, including three drugs that could treat HCC and two drugs that might have side-effect on HCC. In addition, we also make Connectivity Map (CMap) profiles similarity analysis and KEGG enrichment analysis on drug targets. All these findings suggest that our approach is effective for accurate predicting novel therapeutic options for HCC and easily to be extended to other tumors.

Is there a role for thioguanine therapy in IBD in 2017 and beyond?

Conventional thiopurines are effective for the maintenance of remission of Crohn's disease and ulcerative colitis, however, up to half of patients are intolerant or unresponsive to these medications. Thioguanine is an alternative thiopurine that has shown efficacy in inflammatory bowel disease, and is particularly useful to circumvent certain side effects associated with conventional thiopurines, for example, pancreatitis. Its association with nodular regenerative hyperplasia of the liver has hindered its widespread use. Areas covered: We aim to outline the rational use of thioguanine, including safety monitoring, with particular regard to hepatotoxicity. A literature search was performed: PubMed was searched for full papers and abstracts published in English since January 2000 using the following terms, alone and in combination: 'azathioprine', 'thiopurine', 'Crohn's disease', 'inflammatory bowel disease', 'nodular regenerative hyperplasia', 'mercaptopurine', 'thioguanine', 'ulcerative colitis'. Further relevant papers were identified from the reference lists of selected papers. Expert commentary: Despite optimisation strategies such as metabolite measurements and the use of allopurinol, a significant proportion of patients will remain intolerant to thiopurines, especially those with allergic reactions, including pancreatitis. For this subgroup of patients we suggest that low dose thioguanine is an alternative to other therapies that are either parenteral or expensive.

Splitting a therapeutic dose of thioguanine may avoid liver toxicity and be an efficacious treatment for severe inflammatory bowel disease: a 2-center observational cohort study

BACKGROUND

Thioguanine (TG) is a treatment for inflammatory bowel disease, but association with nodular regenerative hyperplasia has restricted its use. We conjectured that splitting a therapeutic daily dose of TG would be efficacious and should avoid liver toxicity.

METHODS

We report on 62 patients with severe inflammatory bowel disease not responding to prednisolone, conventional thiopurines, biologics, or calcineurin inhibitors. Patients were prescribed oral split-daily TG to avoid individual doses >0.3 mg/kg. Data on concomitant medication, clinical efficacy measured by Harvey-Bradshaw Index for Crohn's, or Simple Clinical Colitis Score for ulcerative/indeterminate colitis (UC), and some paired endoscopies were available. Safety was followed clinically and with bloods at 2 centers. All patients at the U.K. center had a liver biopsy or magnetic resonance imaging after 6 months. Twenty-one patients had serial ultrasounds at the Australian center.

RESULTS

At 6 months, 19/21 of patients with Crohn's disease and 27/38 with ulcerative colitis had improved clinical activity. At study end, 53% of patients maintained improved clinical activity of steroids. Median duration of TG was 8 (0.3-45) months, median dose was 0.6 (0.3-1) mg/kg per day. Previous thiopurine-related adverse reactions were not encountered. Twenty-nine patients withdrew because of loss to follow-up, medical adverse events, or surgery. Possible early nodular regenerative hyperplasia was found on liver biopsy in 1 patient who was heterozygote deficient for thiopurine methyltransferase; the TG dose was lowered. TG was discontinued in a patient with nodular regenerative hyperplasia and concomitant antiphospholipid syndrome. There was 1 successful term pregnancy; cord blood and breast milk TG were low.

CONCLUSIONS

Split-dose TG seemed well tolerated and efficacious in this retrospective study of patients with difficult inflammatory bowel disease.

Oral 6-mercaptopurine versus oral 6-thioguanine and veno-occlusive disease in children with standard-risk acute lymphoblastic leukemia: report of the Children's Oncology Group CCG-1952 clinical trial

The Children's Cancer Group 1952 (CCG-1952) clinical trial studied the substitution of oral 6-thioguanine (TG) for 6-mercaptopurine (MP) and triple intrathecal therapy (ITT) for intrathecal methotrexate (IT-MTX) in the treatment of standard-risk acute lymphoblastic leukemia. After remission induction, 2027 patients were randomized to receive MP (n = 1010) or TG (n = 1017) and IT-MTX (n = 1018) or ITT (n = 1009). The results of the thiopurine comparison are as follows. The estimated 7-year event-free survival (EFS) for subjects randomized to TG was 84.1% (+/- 1.8%) and to MP was 79.0% (+/- 2.1%; P = .004 log rank), although overall survival was 91.9% (+/- 1.4%) and 91.2% (+/- 1.5%), respectively (P = .6 log rank). The TG starting dose was reduced from 60 to 50 mg/m(2) per day after recognition of hepatic veno-occlusive disease (VOD). A total of 257 patients on TG (25%) developed VOD or disproportionate thrombocytopenia and switched to MP. Once portal hypertension occurred, all subjects on TG were changed to MP. The benefit of randomization to TG over MP, as measured by EFS, was evident primarily in boys who began TG at 60 mg/m(2) (relative hazard rate [RHR] 0.65, P = .002). The toxicities of TG preclude its protracted use as given in this study. This study is registered at http://clinicaltrials.gov as NCT00002744.

Oral 6-mercaptopurine versus oral 6-thioguanine and veno-occlusive disease in children with standard-risk acute lymphoblastic leukemia: report of the Children's Oncology Group CCG-1952 clinical trial

The Children's Cancer Group 1952 (CCG-1952) clinical trial studied the substitution of oral 6-thioguanine (TG) for 6-mercaptopurine (MP) and triple intrathecal therapy (ITT) for intrathecal methotrexate (IT-MTX) in the treatment of standard-risk acute lymphoblastic leukemia. After remission induction, 2027 patients were randomized to receive MP (n = 1010) or TG (n = 1017) and IT-MTX (n = 1018) or ITT (n = 1009). The results of the thiopurine comparison are as follows. The estimated 7-year event-free survival (EFS) for subjects randomized to TG was 84.1% (+/- 1.8%) and to MP was 79.0% (+/- 2.1%; P = .004 log rank), although overall survival was 91.9% (+/- 1.4%) and 91.2% (+/- 1.5%), respectively (P = .6 log rank). The TG starting dose was reduced from 60 to 50 mg/m(2) per day after recognition of hepatic veno-occlusive disease (VOD). A total of 257 patients on TG (25%) developed VOD or disproportionate thrombocytopenia and switched to MP. Once portal hypertension occurred, all subjects on TG were changed to MP. The benefit of randomization to TG over MP, as measured by EFS, was evident primarily in boys who began TG at 60 mg/m(2) (relative hazard rate [RHR] 0.65, P = .002). The toxicities of TG preclude its protracted use as given in this study. This study is registered at http://clinicaltrials.gov as NCT00002744.

Toxicity and efficacy of 6-thioguanine versus 6-mercaptopurine in childhood lymphoblastic leukaemia: a randomised trial

BACKGROUND

6-mercaptopurine has been a standard component of long-term continuing treatment for childhood lymphoblastic leukaemia, whereas 6-thioguanine has been mainly used for intensification courses. Since preliminary data have shown that 6-thioguanine is more effective than 6-mercaptopurine, we compared the efficacy and toxicity of the two drugs for childhood lymphoblastic leukaemia.

METHODS

Consecutive children with lymphoblastic leukaemia diagnosed in the UK and Ireland between April, 1997, and June, 2002, were randomly assigned either 6-thioguanine (750 patients) or 6-mercaptopurine (748 patients) during interim maintenance and continuing therapy. All patients received 6-thioguanine during intensification courses. We analysed event-free and overall survival on an intention-to-treat basis. We obtained toxicity data using an adverse-event reporting system, with follow-up questionnaires to seek detailed information for specific toxicities. This trial is registered with the International Standard Randomised Controlled Number 26727615 with the name ALL97.

FINDINGS

After a median follow up of 6 years, there was no difference in event-free or overall survival between the two treatment groups. Although 6-thioguanine conferred a significantly lower risk of isolated CNS relapse than did 6-mercaptopurine (odds ratio [OR] 0.53, 95% CI 0.30-0.92, p=0.02), the benefit was offset by an increased risk of death in remission (2.22, 1.20-4.14, p=0.01), mainly due to infections during continuing therapy. Additionally, 95 patients developed veno-occlusive disease of the liver. Of these, 82 were randomly assigned 6-thioguanine, representing 11% of all 6-thioguanine recipients. On long-term follow-up, about 5% of 6-thioguanine recipients have evidence of non-cirrhotic portal hypertension due to periportal liver fibrosis or nodular regenerative hyperplasia.

INTERPRETATION

Compared with 6-mercaptopurine, 6-thioguanine causes excess toxicity without an overall benefit. 6-mercaptopurine should remain the thiopurine of choice for continuing therapy of childhood lymphoblastic leukaemia.

Vascular Toxicity of Antineoplastic Agents

Among the various deleterious effects of cancer chemotherapy, vascular toxicity is the least well recognized. This lack of recognition may be because the vasculotoxic phenomena are not unique to antineoplastic agents, can occur in patients without exposure to these agents, and the fact cancer itself may produce a hypercoagulable state. As a result, many vascular events either go unnoticed, are ignored, and/or are attributed to the underlying malignancy. Many antineoplastic therapies are associated with various vascular phenomena that range from simple phelibitis to lethal microangiopathy. Recognition of these events is important to minimize the morbidity and even prevent unnecessary deaths. Herein we review the vascular syndromes that have been reported in association with antineoplastic agents.

Hepatotoxicity of Chemotherapy

The selection of an antineoplastic regimen for an oncology patient is based first on the availability of effective drugs and then on a balancing of potential treatment-related toxicities with the patient's clinical condition and associated comorbidities. Liver function abnormalities are commonly observed in this patient population and identifying their etiology is often difficult. Immunosuppression, paraneoplastic phenomena, infectious diseases, metastases, and poly-pharmacy may cloud the picture. While criteria for standardizing liver injury have been established, dose modifications often rely on empiric clinical judgment. Therefore, a comprehensive understanding of hepatotoxic manifestations for the most common chemotherapeutic agents is essential. We herein review the hepatotoxicity of commonly used antineoplastic agents and regimens.

Veno-occlusive disease of the liver associated with chronic myelomonocytic leukemia treated with vincristine and standard doses of cytarabine

A unique case of a 72-year-old man with chronic myelomonocytic leukemia (CMML) who developed hepatic veno-occlusive disease (VOD) after treatment with a single dose of vincristine and standard doses of cytarabine is described. Unexpected peroneal nerve palsy suggestive of vincristine neurotoxicity occurred concurrently and pointed to vincristine as the most likely cause of the VOD. To the best of our knowledge, association between vincristine and hepatic VOD has not been previously described in chemotherapy-naive patients with CMML.

Portal hypertension develops in a subset of children with standard risk acute lymphoblastic leukemia treated with oral 6-thioguanine during maintenance therapy

BACKGROUND

6-Thioguanine (TG) was recently studied to determine whether TG in maintenance therapy achieves better event free survival than 6-mercaptopurine (MP) for standard risk acute lymphoblastic leukemia (ALL) on the clinical trial, CCG-1952 (5/1996-1/2000). Veno-occlusive disease was previously recognized as a complication of TG on CCG-1952. We report a newly recognized pediatric complication of TG: splenomegaly and portal hypertension (PH) developing during maintenance or after completion of therapy.

PROCEDURE

Twelve patients (3-10 years) had been randomized to receive a targeted dose of 50 mg/m(2)/day of TG during maintenance phases. Actual TG dose ranged from 25 to 77 mg/m(2)/day (median 34 mg/m(2)/day).

RESULTS

The initial patient, a boy who had marked thrombocytopenia and intermittent splenomegaly during maintenance therapy, was evaluated for persistent pancytopenia and progressive splenomegaly 3 months after completion of therapy. Dilated splenic vein and collaterals consistent with PH were documented by MRI/MRA. Esophagogastroduodenoscopy found esophageal varices. Liver biopsy showed periportal fibrosis and marked dilatation of veins and venules. Of the other 12 patients, 9 patients studied had abnormal MRI/MRAs with evidence of varices in 4. Eight patients had splenomegaly on physical examination. Liver biopsies in a girl after 3.3 courses of TG and a boy after 4.6 courses of TG showed periportal fibrosis and dilatation of venules and sinusoids and minimal focal fatty changes. Subsequent MRI/MRAs have been stable or improved.

CONCLUSIONS

The evaluations of these 12 patients suggest that treatment with TG causes injury to the liver leading to PH and that thrombocytopenia and splenomegaly are clinical hallmarks of this toxicity.

Early Hepatic Nodular Hyperplasia and Submicroscopic Fibrosis Associated With 6-Thioguanine Therapy in Inflammatory Bowel Disease

BACKGROUND

6-Thioguanine (6-TG) has been used as an alternative thiopurine for inflammatory bowel disease (IBD) patients not responsive to or intolerant of azathioprine (AZA) and 6-mercaptopurine (6-MP). 6-TG-related hepatotoxicity, including liver biochemistry value elevations, sinusoidal collagen deposition on electron microscopy, and veno-occlusive disease, have been described related to its use as therapy for neoplastic disease.

METHODS

We studied 38 liver biopsies from patients treated with 6-TG, almost all of whom (n = 125) received 6-TG for 1 to 3 years at the Inflammatory Bowel Disease Center at Cedars-Sinai Medical Center. All biopsies were fixed in 4% buffered formalin and prepared in the usual manner. Hematoxylin and eosin, Masson's trichrome (trichrome), and reticulin silver impregnation (reticulin) stained slides were studied. In 23 cases, tissue was also prospectively fixed in glutaraldehyde and processed for electron microscopy.

RESULTS

In 20 of the 37 patients studied (53%), nodular regeneration of varying degree was seen with reticulin. In only 4 of these 20 instances (11% of the total) were the changes seen with hematoxylin and eosin and in 3 of the 4, only in retrospect after studying the reticulin preparation. Minimal fibrosis was seen with trichrome in only 13 biopsies (34%), but sinusoidal collagen deposition was observed in 14 of the 23 cases studied with electron microscopy (60%). The biopsy from the 1 patient with nodular hyperplasia obvious with hematoxylin and eosin also demonstrated changes of venous outflow obstruction.

CONCLUSIONS

6-TG-treated IBD patients are at significant risk for nodular hyperplasia, early fibrosis and, less often, venous outflow disease (Budd-Chiari). The natural history of these changes is unknown and follow-up biopsies are needed to determine histologic and clinical sequela. Patients not demonstrating nodular hyperplasia or fibrosis who continue with 6-TG because there are no better therapeutic choices should be periodically rebiopsied.

Acute sinusoidal obstruction syndrome after 6-thioguanine therapy for Crohn's disease

6-Thioguanine (6-TG), the active metabolite of 6-mercaptopurine and its prodrug azathioprine, are thought to be responsible for clinical efficacy in the treatment of active Crohn's disease. Its use as a therapeutic agent for inflammatory bowel disease (IBD) has been limited to patients who are resistant to or intolerant of other antimetabolites. Short-term experience with this agent has not demonstrated an increased incidence of hematologic or hepatic toxicity; however long-term safety data are scarce. We herein report a patient who developed acute sinusoidal obstruction syndrome after 14 months of successful thioguanine treatment. This is the first report of such a complication in an adult treated with 6-TG for active Crohn's disease.

Early Nodular Hyperplasia of the Liver Occurring With Inflammatory Bowel Diseases in Association With Thioguanine Therapy

Context.—Nodular hyperplasia (also referred to as nodular regenerative hyperplasia and nodular regenerative hyperplasia of the liver) is a sequel to therapy with thioguanine in patients with hematologic malignancies. Recently, 6-thioguanine has been used to treat patients with inflammatory bowel disease who have been resistant to other forms of therapy.

Objective.—To study liver biopsies from 3 patients with inflammatory bowel disease who had received thioguanine for more than a year, and who had elevated serum liver enzyme values and underwent percutaneous liver biopsy.

Design.—Percutaneous liver biopsies and histologic examinations were performed, including staining with the reticulin silver impregnation method.

Results.—All 3 patients had foci of nodular regenerative hyperplasia, which was best seen with the reticulin silver impregnation method.

Conclusions.—Thioguanine-treated inflammatory bowel disease patients are at risk for the development of nodular hyperplasia. Reticulin-stained histologic sections are necessary to recognize this change. Further studies are needed to determine the frequency and significance of this change.

Role of macrophages and stellate cells in the pathogenesis of veno-occlusive disease: an electron microscopic case study

Veno-occlusive disease (VOD) is an entity described as a triad of pathologic findings including ascites, tender hepatomegaly, and elevated liver enzymes. The prognosis of patients suffering from VOD is highly variable, ranging from slow resolution to the need for liver transplant. The histopathology of VOD has been described by light and electron microscopy. However, the pathogenesis of VOD is still largely unclear. In the present case study, we report the significant findings in a case of pediatric VOD following chemotherapy. We studied the liver biopsy by light and electron microscopes. In addition to previous reported findings of occlusion of the central vein with endothelial cell damage, proliferation and activation of stellate cells, and collagen deposition in the central vein wall, there were prominent activated macrophages within the lumen and wall of central veins. The following mechanism of VOD was proposed: Tissue damage activates monocytes through monocyte chemoattractant protein-1. The secretory macrophages release TGF-beta, which promotes proliferation of stellate cells to cause collagenous thickening of the central vein. The activated stellate cells produce collagen. The normal drainage of the Space of Disse and sinusoids draining into the central vein are blocked by the fibrosis. This leads to extravasated RBCs trapped within the thickened central vein wall and impaction of RBCs in the sinusoids.

Tioguanine in patients with Crohn's disease intolerant or resistant to azathioprine/mercaptopurine

BACKGROUND

Tioguanine (TG) is an antimetabolite which may be regarded as an alternative to azathioprine (AZA)/mercaptopurine (MP) in patients with inflammatory bowel diseases.

AIMS

: To evaluate the tolerance and efficacy of TG in patients with Crohn's disease, intolerant or resistant to AZA/MP.

METHODS

An open prospective study was made on Crohn's disease patients treated with TG. Intolerance to AZA/MP was defined as a reaction occurring within 1 month after introduction of AZA/MP, including pancreatitis, abdominal pain, fever, arthralgia, myalgia, cutaneous rash, fatigue, alopecia, hepatitis and digestive intolerance. Resistance to AZA/MP was defined as the persistence of activity after at least 3 months of AZA/MP therapy.

RESULTS

Forty-nine Crohn's disease patients (36 women, 13 men; intolerance: n = 39; resistance: n= 10) were treated with TG (20 mg/day). Clinical pancreatitis did not recur under TG. Five patients (10%) had to stop TG due to intolerant reactions observed 13-21 days after TG was started. No haematological side-effects were observed under TG. The probability of clinical remission without corticosteroids or infliximab at 6 and 12 months was 46% and 79%, respectively, in the 40 patients with active disease at baseline. The probability of clinical relapse during maintenance TG therapy at 6 and 12 months was 29% and 53%, respectively, in the 28 patients in remission at baseline or who had achieved remission on TG.

CONCLUSIONS

TG is a possible alternative treatment in Crohn's disease patients, intolerant (especially for pancreatitis) or resistant to AZA/MP.

Thioguanine: a potential alternate thiopurine for IBD patients allergic to 6-mercaptopurine or azathioprine

OBJECTIVE

Approximately 10% of inflammatory bowel disease (IBD) patients receiving 6-mercaptopurine (6-MP) or azathioprine (AZA) develop drug hypersensitivity reactions necessitating early discontinuation of these traditional thiopurines. These allergic reactions typically reoccur upon rechallenge. Our recently published pilot study suggested that thioguanine (6-TG), a closely related thiopurine, was efficacious and well tolerated in IBD patients resistant to 6-MP/AZA. The aim of this study was to determine if hypersensitivity reactions to 6-MP/AZA reoccur with 6-TG therapy.

METHODS

IBD patients allergic to 6-MP and/or AZA were treated with 6-TG as an alternate thiopurine. Hypersensitivity reactions to 6-MP/AZA must have been documented within 6 wk of 6-MP/AZA initiation.

RESULTS

6-TG was initiated in 21 IBD patients at a median (range) dose of 20 (10-40) mg/day. 6-TG hypersensitivity reaction occurred in only four of 21 (19%) patients after a median time interval of 9 days. Pancreatitis did not reoccur with 6-TG. Eighty-two percent of 6-TG tolerant patients were assessed as improved at last follow-up.

CONCLUSIONS

These results suggest that 6-TG may be considered as a possible alternate thiopurine in patients allergic to traditional 6-MP/AZA. Despite these favorable results, candidates for 6-TG should be selected with caution, and its use should be reserved for IBD patients well informed about potential toxicities.

Hepatotoxicity associated with 6-thioguanine therapy for Crohn's disease

6-Thioguanine (6-TG) is a thiopurine analogue that is closely related to 6-mercaptopurine (6-MP) and azathioprine (AZA). These agents have potent cytotoxic and immunomodulatory effects and are useful in the treatment of a variety of conditions, including inflammatory bowel disease. Both 6-MP and AZA are widely used and are known to cause hepatotoxicity in a proportion of patients. 6-Thioguanine is being increasingly used in the treatment of inflammatory bowel disease but has not been reported to cause liver injury in this context. We describe a case of significant elevation of serum transaminases in a patient treated with 6-TG for a flare of Crohn's disease. We believe the temporal association of the abnormal liver enzymes in this patient, in the absence of other offending agents, argues strongly in favor of 6-TG as a cause of liver enzyme abnormalities. This case highlights the need to monitor liver enzymes in patients treated with 6-TG and identifies the need for additional research focused on the mechanism of thiopurine-induced hepatic injury.

Hepatotoxicity of chemotherapy

The selection of a chemotherapeutic regimen for the oncology patient is based on a thorough assessment of potential hazards relating to the patient's clinical condition and the toxicities of chemotherapy. Liver function abnormalities are commonly seen in this patient population and deducing their aetiology may be difficult. Immunosuppression, paraneoplastic phenomena, infectious disease, metastases and polypharmacy may all confound the clinical picture. While criteria for standardising liver injury have been established, dose modifications often rely on empirical clinical judgement. Therefore, a comprehensive understanding of hepatotoxic manifestations for the most common chemotherapeutic agents is essential. This article reviews the hepatotoxicity of commonly utilised antineoplastic agents.

Gemtuzumab ozogamicin (Mylotarg) monotherapy for relapsed AML after hematopoietic stem cell transplant: efficacy and incidence of hepatic veno-occlusive disease

Gemtuzumab ozogamicin (GO) (Mylotarg, CMA-676) is a novel chemotherapeutic agent consisting of an anti-CD33 monoclonal antibody linked to calicheamicin, and is associated with a 30% response rate in patients with CD33-positive acute myeloid leukemia (AML) in first relapse. GO therapy has a 20% incidence of grade 3 or 4 hepatotoxicity, and has recently been associated with hepatic veno-occlusive disease (VOD). The efficacy and toxicity of GO in patients with AML who have relapsed after hematopoietic stem cell transplant (HSCT) is unknown, as this population was largely excluded from phase II studies. We reviewed the outcomes of eight consecutive patients with AML who received GO following relapse after HSCT. Two (25%) had responses to GO. One patient, who had had two previous HSCT and prior hyperbilirubinemia, developed severe VOD and died 14 days after GO therapy. The other seven patients did not meet diagnostic criteria for VOD. We conclude that GO can be safe and effective in patients who relapse following HSCT, but that caution is warranted in patients with multiple risk factors for VOD.

Mylotarg (gemtuzumab ozogamicin) therapy is associated with hepatic venoocclusive disease in patients who have not received stem cell transplantation

BACKGROUND

Mylotarg (Wyeth-Ayerst Laboratories, St. Davids, PA) is the brand name for a calicheamicin-conjugated humanized anti-CD33 monoclonal antibody (gemtuzumab ozogamicin, CMA-676) and has been approved recently for the treatment of a subset of elderly patients who have relapsed acute myeloid leukemia (AML). Mylotarg is associated with an incidence of approximately 20% Grade 3 or 4 hyperbilirubinemia and liver transaminitis in this patient population. Hepatic venoocclusive disease (VOD) has been reported in patients who have undergone stem cell transplantation (SCT) after Mylotarg therapy. Outside of the SCT setting, VOD has been associated very rarely with cytotoxic therapy.

METHODS

The authors assessed the incidence of VOD in 119 patients who were receiving Mylotarg-containing non-SCT regimens. VOD was diagnosed through the use of standard Seattle and Baltimore criteria.

RESULTS

A cohort of 119 (61 previously untreated, 58 with relapsed disease) patients with AML (92 patients), advanced myelodysplastic syndrome (25 patients), or chronic myeloid leukemia in blast phase (2 patients), received Mylotarg-based regimens. Fourteen (12%) developed VOD. The diagnosis of VOD was supported by histology in 2 patients and radiologic studies in a further 10 patients. Five (36%) of 14 patients with VOD had received no prior antileukemic cytotoxic therapy, including 2 patients who received single-agent Mylotarg therapy.

CONCLUSIONS

Mylotarg was shown to be associated with the development of potentially fatal VOD in patients with leukemia who had not received SCT. VOD occurred when Mylotarg was used either as a single agent or when it was given with other cytotoxic agents. VOD occurred in Mylotarg-treated patients who had received no prior cytotoxic therapy. The current study concluded that risk factors for VOD should be assessed when considering Mylotarg therapy, and that attempts to avoid and treat VOD are warranted in patients who receive Mylotarg therapy.

Hepatotoxicity of chemotherapy

After assessment of tumor histology, the next important factor to consider in the selection of a chemotherapy regime is organ function. Patients who are to receive chemotherapy require careful assessment of liver function prior to treatment to determine which drugs may not be appropriate, and which drug doses should be modified. Following therapy abnormalities of liver function tests may be due to the therapy rather than to progressive disease, and this distinction is of critical importance. Furthermore, not all abnormalities in liver function are due to the tumor or its treatment, and other processes, such as hepatitis, must be kept in mind. This article reviews the hepatic toxicity of chemotherapeutic agents, and suggests dose modifications based upon liver function abnormalities. Emphasis is placed on agents known to be hepatotoxic, and those agents with hepatic metabolism.

Antimetabolites and cytotoxic drugs

Mycophenolic mofetil, azathioprine, thioguanine, methotrexate, and cyclophosphamide were initially used for the treatment of malignancies. Because of their immunosuppressive activity, the range of diseases responsive to these medications has expanded to include various autoimmune-related diseases. Discussion includes a historical perspective of each medication, recent updates on responsive dermatologic conditions, dosages, monitoring guidelines, and medication expense.

Coagulation disorders in cancer

Coagulation disorders are common in cancer patients. This article reviews the coagulation laboratory findings in these patients and the thromboembolic and hemorrhagic manifestations of malignancy. Among the many topics addressed are Trousseau's syndrome, disseminated intravascular coagulation, and acquired von Willebrand disease. Pathogenesis of the coagulation disorders and recommendations for treatment of various syndromes are discussed.

Recombinant tissue plasminogen activator (rt-PA) for veno-occlusive liver disease in pediatric autologous bone marrow transplant patients

The pathogenesis of veno-occlusive disease (VOD) of the liver appears to be secondary to endothelial damage of terminal hepatic venules, which leads to activation of the coagulation cascade, fibrin deposition, and eventual fibrous obliteration of the hepatic venules. Patients with VOD usually present with jaundice, hepatomegaly, weight gain, and ascites. This complication is usually associated with a high mortality rate. We report here the frequency and treatment of VOD in our autologous bone marrow transplant (BMT) patient population. Three of 15 (20%) children (median age 9 years) developed VOD and were treated with recombinant tissue plasminogen activator (rt-PA). Two of these three patients were prepared for BMT with busulfan (16 mg/kg) and cyclophosphamide (Cytoxan, 200 mg/kg), while the other child received cytosine arabinoside (ARA-C 18 g/m2), Cytoxan (3,600 mg/m2) and total body irradiation (TBI, 1,400 y). VOD developed between days 7-24 posttransplant. Clotting studies obtained pretransplant and during VOD included prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, fibrin-degradation product (FDP), proteins C and S, and platelet count. There was no correlation between the incidence of VOD and coagulation status. All patients had normal pretransplant clotting studies. However, protein C levels were noted to be consistently low for those patients at the time of VOD. All three patients received rt-PA at a dose of 0.25-0.5 mg/kg for 4 days. This dose produced increased levels of FDP but did not significantly prolong PT nor PTT. Two of the patients had dramatic responses and had complete resolution of VOD within 6-12 days from the start of therapy. The other patient died of fulminant hepatic failure. It seems that rt-PA is effective in VOD of the liver, which may be associated with low protein C level.

Effective early treatment of hepatic venoocclusive disease with a central splenorenal shunt in an infant

Venoocclusive disease of the liver (VOD) is a well-described complication following chemotherapy. It is manifested by jaundice and signs of portal hypertension and carries a mortality rate approaching 50%. There is no known treatment for the disease itself, although several recent reports suggest portacaval diversion may be effective in treating its sequelae. A 6.75-kg 8-month-old boy with VOD following bone marrow ablation and bone marrow transplantation (BMT) for juvenile chronic myelogenous leukemia (JCML) is presented. Over a 6-week period following bone marrow ablation he developed ascites refractory to diuretics, jaundice, and hematemasis with normal hepatocellular function. Splenectomy with a central splenorenal shunt was performed, which resulted in a significant reduction in portal pressures and complete resolution of his ascites and hematemasis without resultant encephalopathy. We propose that central end-to-side splenorenal shunting is an acceptable treatment for portal hypertension due to VOD and can be successfully performed in infants.

Prophylactic heparin does not prevent liver veno-occlusive disease following autologous bone marrow transplantation

Veno-occlusive disease (VOD) is a major cause of toxic death after autologous bone marrow transplantation (ABMT). We studied the potential role of continuous administration of low-dose heparin for VOD prevention in 234 consecutive patients who underwent ABMT in our institution. The population consisted of 98 patients autografted before October 1984 who did not receive heparin, and a series of 136 patients autografted from October 1984 to March 1989 containing 98 patients included in a randomized trial comparing heparin administration (n = 52) vs no heparin (n = 46), and an additional group of 38 patients who received non-randomized heparin in view of high-risk criteria to develop VOD (n = 31) or other reasons unrelated to VOD (n = 7). Overall, 90 patients (38%) received heparin and 144 (62%) did not. The global incidence of VOD was 13/234 (5-5%). Heparin did not reduce the risk of VOD in all subgroups studied. In particular, in the randomized trial, the incidence of VOD was 2.2% in the group without heparin vs 7-7% in the group receiving heparin. We analyzed in depth the 13 patients who developed VOD and we compared them to a control group of 13 patients pair-matched for age, sex, diagnosis and preparative regimen, who did not develop VOD. We found that abnormal LFT before ABMT predisposed patients to VOD; refractoriness to platelet transfusion was observed in 85% of the patients in the VOD group vs 15% in the control group (p less than 0.05). VOD patients had an increased requirement for red cells and platelet transfusions, a lower recovery (R less than 25%) after the second and third platelet transfusion, and shorter intervals separating the first four platelet transfusions. Further, the platelet reconstitution after ABMT in the VOD group was slower in comparison to the control group (p less than 0.01). Again, in this pair-matched analysis continuous infusion of low-dose heparin did not prevent VOD.

Thioguanine used in maintenance therapy of chronic myeloid leukaemia causes non-cirrhotic portal hypertension. Results from MRC CML. II. Trial comparing busulphan with busulphan and thioguanine

Portal hypertension with varices developed in 18/675 patients with chronic myeloid leukaemia (CML) in a randomized trial comparing busulphan with busulphan and thioguanine. All 18 had received the drug combination and none busulphan alone (P less than 0.0001). Ascites was also seen significantly more often in the combination arm (P less than 0.05). These results strongly suggest that the addition of thioguanine was responsible for the development of portal hypertension. The histological features were predominantly those of non-cirrhotic portal hypertension--either idiopathic portal hypertension with minimal morphological abnormalities, nodular regenerative hyperplasia or in two cases leukaemic infiltration only was noted. Cirrhosis was present in 3/16 cases studied. Both treatment groups developed abnormal liver function tests during the chronic phase, but particularly with progression of the disease. During chronic phase abnormalities were significantly more frequent in those receiving busulphan and thioguanine-alkaline phosphatase (P less than 0.02), transaminases (P less than 0.04), bilirubin (P less than 0.05), multiple abnormalities (P less than 0.01). The development of portal hypertension was often associated with abnormalities of these tests; however, lack of specificity precludes their use as a predictor of subsequent clinical problems. Thioguanine confers no survival advantage in this disease. In view of its hepatotoxicity it should not be used routinely for maintenance of control in chronic phase CML.

Purine metabolism as a target for leukemia chemotherapy

This article focuses on the chemotherapeutic agents which alter purine metabolism as a means to achieve selective killing of leukemic cells. We present an overview of purine metabolism in order to highlight enzymatic steps which are targeted by antileukemic drugs. Purine antimetabolites used in the treatment of leukemia can be grouped into three classes: (1) structural analogs of normal purines (6-mercaptopurine and 6-thioguanine); (2) inhibitors of de novo purine biosynthesis (methotrexate and hydroxyurea); and (3) inhibitors of purine salvage (2'-deoxycoformycin). In addition, a number of investigational drugs (trimetrexate, fludarabine and 2'-chlorodeoxyadenosine) have been recently introduced and show promise in early clinical trials. Purine antimetabolites are active in a variety of lymphoid and myeloid leukemias and represent an important component of the therapy of these disorders. Several of the drugs have been developed with the specific intent of perturbing enzymes involved in purine metabolism. Refinements in our understanding of purine biochemistry in normal and leukemic cells may aid future efforts to design more effective drugs.

A comparative pathological study of liver injury after different combination chemotherapies for leukemia

A form of liver injury characterized by bile ductule-like transformation of hepatocytes, prominent hemosiderin deposition and fibrosis, was occasionally encountered in autopsy cases we examined during the period from 1973 to 1981. It was found that this liver injury was irreversible and intimately related to combination chemotherapy with the DCMP regimen (daunorubicin, cytosine arabinoside, 6MP and prednisolone) for acute non-lymphocytic leukemia (ANLL). Its correlation was reconfirmed by the fact that this liver injury disappeared after withdrawal of the DCMP regimen in 1981. After 1978, the regimen of combination chemotherapy for adult ANLL was partly changed, 6-thioguanine being utilized (DCTP) instead of the 6MP in the DCMP regimen. The hepatic injury occurring after the change in the regimen was different from that produced with DCMP, showing reversible intrahepatic cholestasis. These facts indicated that substitution for one drug in a combination chemotherapy regimen could cause a different type of hepatic change.

Drug-induced vascular and sinusoidal lesions of the liver

Drugs can induce various vascular and sinusoidal lesions of the liver, in particular hepatic vein thrombosis, veno-occlusive disease, sinusoidal dilatation, peliosis hepatis, hepatoportal sclerosis and angiosarcoma. None of these lesions is specific of drug-induced injury and all of them can be determined by causes other than drugs. However, for one of these lesions, veno-occlusive disease, chemotherapy (and/or irradiation) represents the main aetiology.

Oesophageal varices associated with busulphan-thioguanine combination therapy for chronic myeloid leukaemia

5 patients receiving continuous busulphan and 6-thioguanine for chronic myeloid leukaemia (CML) were found to have oesophageal varices associated with abnormal liver function tests. 3 of these cases presented with gastrointestinal haemorrhage and 1 patient died. The 2 other cases had varices discovered at endoscopy. Nodular regenerative hyperplasia (NRH) of the liver was identified as the cause of portal hypertension in the 4 patients on whom liver biopsies were done. The administration of busulphan and thioguanine in combination is likely to be associated with the development of NRH, with portal hypertension and oesophageal varices occurring in a substantial proportion of cases.

Successful treatment of hepatic venocclusive disease in a bone marrow transplant patient with side-to-side portacaval shunt

Hepatic venocclusive disease developed in a 14-yr-old white girl after allogenic bone marrow transplantation from an HLA-identical sibling donor. Clinical diagnosis of venocclusive disease was based on the development of ascites, hepatomegaly, and jaundice 3 wk after transplantation. Current treatment of hepatic venocclusive disease is ineffective. The pathophysiology of the hepatic lesion suggests that construction of a side-to-side portacaval shunt should be beneficial in relieving the ascites and preventing further hepatic damage. Because the ascites was refractory to medical therapy and she was clinically deteriorating, a side-to-side portacaval shunt was performed. Histologic examination of a liver biopsy specimen obtained at surgery documented the presence of venocclusive disease. Postoperatively, the patient diuresed and returned to her baseline weight. One year after surgery the patient was doing well, her weight was stable, and she was being maintained on salt restriction alone. While the resolution of ascites and improvement of hepatic function in our patient after side-to-side portacaval shunt does not guarantee that such an approach will be uniformly successful, it should serve to encourage others to consider such therapy for this frequently devastating complication of chemoradiation therapy.

Hepatic vein lesions in alcoholic liver disease: retrospective biopsy and necropsy study

Obliteration of the terminal hepatic venules with perivenular fibrosis (phlebosclerosis) is a well recognised feature in alcoholic liver disease. Veno-occlusive lesions with intimal obliteration of hepatic veins and a lymphocytic phlebitis of hepatic veins may also be present. We looked for these lesions in 256 liver biopsies and 50 livers obtained at necropsy from patients with alcoholic liver disease. Phlebosclerosis was a universal finding in alcoholic hepatitis and cirrhosis and showed increasing severity with progressive liver injury. Veno-occlusive lesions, however, were found in only 25 of 256 (9.8%) of biopsies and 11 of 50 (22%) of livers obtained at necropsy, showing alcoholic hepatitis or cirrhosis: lymphocytic phlebitis was found in 10 of 256 (3.9%) and two of 50 (4%), respectively. Moreover, veno-occlusive lesions were generally mild. The prevalence of veno-occlusive lesions and lymphocytic phlebitis was considerably less than has been previously documented. Phlebosclerosis may have a different mechanism and be a more important contributory factor in progressive liver injury.

Marrow transplantation in hepatitis-associated aplastic anemia

Seventeen patients who developed aplastic anemia in association with viral hepatitis were transplanted with sibling marrow. Of the 16 HLA-identical recipients, 14 were conditioned with cyclophosphamide, 200 mg/kg, and two received 10 Gy total body irradiation. One HLA-nonidentical recipient received 123 mg/kg cyclophosphamide and 10 Gy total body irradiation. Of the 14 patients conditioned with cyclophosphamide alone, one died on day 49 after graft rejection, and 13 had sustained engraftment. Six of the 13 developed acute graft-versus-host disease (GVHD), which led to death from opportunistic infections 84, 97, and 130 days after transplantation in three patients. Four of the 13 developed chronic GVHD, two without preceding acute GVHD. Currently, ten of the 14 cyclophosphamide-conditioned patients are alive 0.9-12.4 (median 5.9) years from transplantation. The two HLA-identical recipients conditioned for grafting with total body irradiation died after failure of engraftment, and one also developed concomitant hepatic venocclusive disease. The mismatched recipient conditioned with radiation and cyclophosphamide died of severe GVHD 18 days posttransplant. We conclude that survival, graft rejection, and incidence of acute and chronic GVHD after marrow transplantation for hepatitis-associated aplastic anemia are similar to those of patients transplanted for aplastic anemia of other etiologies. Previous hepatic damage from viral hepatitis and liver function abnormalities existing at the time of grafting do not appear to increase the risk of posttransplant morbidity and mortality from hepatocellular damage or venocclusive disease in cyclophosphamide-conditioned patients.

Venocclusive disease of the liver after bone marrow transplantation: diagnosis, incidence, and predisposing factors

Venocclusive disease (VOD) of the liver, a fibrous obliteration of small hepatic venules, can be caused by chemoradiation therapy. We reviewed 255 consecutive patients undergoing bone marrow transplantation for malignancy during 1978 to 1980 in order to determine the incidence of VOD and the predisposing factors. Fifty-three of 255 patients met our criteria for VOD, for an incidence of 21%. Multivariate analysis showed that the most significant risk factors for VOD were age over 15, an underlying malignancy other than acute lymphocytic leukemia and hepatitis prior to transplantation. Patients with hepatitis had a 3.4-fold risk of developing VOD, as compared to patients with normal SGOT values (p = 0.0004). Hepatitis in this setting is probably of non-A, non-B viral etiology and represents a relative contraindication to marrow transplantation because of enhanced toxicity from conditioning chemoradiotherapy.

Drug effects on the liver. An updated tabular compilation of drugs and drug-related hepatic diseases

Generic and chemical names of drugs and the possible adverse effects of these drugs on the human liver are tabulated. Most drugs compiled in these tables have been approved by the Federal Drug Administration. They are currently available in the United States, and they are listed in the 1983 Physicians' Desk Reference. Some important investigational drugs are listed also. The tables include: (1) generic names of drugs that have caused a characteristic morphologic change, such as granulomatous hepatitis; (2) morphologic diagnoses that have been documented after administration of each drug; and (3) references that can be matched to each drug and to its effects on the liver.

Drugs and liver disease: a tabular compilation of drugs and the histopathological changes that can occur in the liver

A compilation of drugs and the histopathological changes that can occur in the liver is presented. The purpose of this review is to provide the reader with a comprehensive and reliable source of information on various drugs that have been documented by liver biopsy to cause hepatocellular damage. The morphologic terms used in the tables have been chosen based on past publications dealing with this subject. This review is intended as a concise guide to aid in the identification of drug-induced liver diseases.