State-of-the-Art Review. A Systematic Approach to Hepatic Complications in Hematopoietic Stem Cell Transplantation

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1 JOURNAL OF HEMATOTHERAPY & STEM CELL RESEARCH 11: (2002) Mary Ann Liebert, Inc. State-of-the-Art Review A Systematic Approach to Hepatic Complications in Hematopoietic Stem Cell Transplantation SALLY ARAI, LINDA A. LEE, and GEORGIA B. VOGELSANG ABSTRACT Hepatic injury is a common complication of hematopoietic stem cell transplantation (HSCT) and carries a high risk of early morbidity and mortality. Evaluation of the patient for hepatic complications should begin in the pretransplant period with the identification of pretransplant risk factors, such as hepatitis status, that may predict severe liver complications and continue through the early and late transplant periods. Early hepatic complications include drug toxicity, hepatic venoocclusive disease (VOD), acute graft-versus-host disease (GVHD), infection, and cholestatic disorders. With increased survival of HSCT recipients, long-term liver complications from chronic viral hepatitis, chronic GVHD, and iron overload are being reported. The diagnosis and management of hepatic disorders in transplant can be complex, because one must decide whether a given symptom is due to one or a combination of diverse causes. Making the diagnosis can be crucial, because specific therapies can improve one condition but worsen another. This review describes a systematic approach to the evaluation of HSCT patients with hepatic complications with an emphasis on the need to intervene early with radiologic imaging and liver biopsy. Updated treatment options are also discussed. It is hoped that a standard approach will help to streamline clinical management of these very complex patients. H EPATIC INTRODUCTION DYSFUNCTION is a well-known cause of early morbidity and mortality following hematopoietic stem cell transplantation (HSCT), affecting 80% of patients and responsible for up to 5 15% of toxic-related deaths (1,2). Drug toxicity, veno-occlusive disease (VOD), acute graft-versus-host disease (agvhd), and fungal, bacterial, and viral infections are the most frequent causes of hepatic dysfunction in the early posttransplant period. With the increased survival rate of HSCT recipients, long-term liver dysfunction has become a recognized complication post-transplant. Chronic viral hepatitis, chronic graft-versus-host disease (cgvhd), and iron overload have been the main reported causes (3). This review will present a practical approach to hepatic and biliary complications, starting chronologically in the order that clinicians might encounter these problems post-transplant. Particular emphasis will be placed on diagnostic methods, therapeutic options, and possible prevention. PRETRANSPLANT CONSIDERATIONS Several studies have attempted to define pre-hsct risk factors that may be associated with an increased post- BMT death from liver failure. Some of the risk factors Johns Hopkins Oncology Center, Baltimore, MD

2 ARAI ET AL. TABLE 1. PRETRANSPLANT RISK FACTORS THAT MAY BE ASSOCIATED WITH DEVELOPMENT OF HEPATIC DYSFUNCTION POST-TRANSPLANT Elevated transaminase levels before the start of conditioning therapy risk proportional to aspartate aminotransferase levels Starting conditioning therapy being treated for bacterial or viral infections Patients with liver metastases Prior radiation therapy with fields including the liver Second transplants recipients Prolonged broad-spectrum antibiotic use Amphotercin use during and after conditioning therapy, either for documented fungal infection or empiric treatment of febrile neutropenia Cytoreductive therapy intensive preparative regimens, extensive prior chemotherapy Mismatched or unrelated donor transplant Pre-existing liver disease Hepatitis B or C ongoing or previous infection,?hepatitis G,?TTV that have been described are listed in Table 1. Among these factors, the importance of viral hepatitis markers in HSCT donors and recipients remains unsettled (4). Patients who are already infected with hepatitis viruses at the time of HSCT or become infected through infected donors are potentially at risk for hepatic VOD and/or recurrent hepatitis infection that may lead to fulminant viral hepatitis. Hepatitis is identified as a risk factor for fatal liver toxicity in infected patients having pretransplant AST elevation, with a relative risk of 4.6 (5). However, some authors report an increased risk of VOD in hepatitis C virus (HCV)-infected patients even without aspartate aminotransferase (AST) elevation. Conflicting data prevent a consensus on an approach to pretransplant hepatitis in these patients. In addition, there has been the identification of new viruses, such as hepatitis G virus (HGV) and transfusion-transmitted virus (TTV), which appear to have a high prevalence in the multiply transfused HSCT recipient population. In preliminary studies, there is not a significant association between infection with these viruses and acute liver toxicity in HSCT patients, although further clarification is required (6,7). An approach to the donor or patient infected with hepatitis is shown in Table 2. Hepatitis B infection in the donor It may be the case that the most suitable donor for an HSCT recipient is infected with hepatitis B virus (HBV). The risks of using such a donor depend on the virological and serological HBV markers present in both the donor and recipient. Unfortunately, the HBV markers obtained by institutions are not standardized so that the complete HBV status of donors is not always reported. The suggested panel should include: HBs-Ag, HbeAg, anti- Hbe, and HBV DNA. The literature reports the risk of transmission of HBV from an HBV surface antigen-positive donor to be relatively low, less than 30%, and recipients who become infected with HBV from their donor have a risk of severe hepatitis after transplantation reported to be only 5 15% (8,9). This may be an underestimation, given possible incomplete data to determine the complete HBV status. Still, HBV clearly can be transmitted from hepatitis B surface antigen (HbsAg)-positive donors to naïve or anti-hbs positive recipients. The infection tends to be more severe when the recipient has no serologic markers of prior HBV infection. The risk of transmission is small from a donor who is only anti-hbc positive, but confirmation with HBV DNA should be TABLE 2. SUGGESTED APPROACH TO VIRAL HEPATITIS IN THE DONOR AND PATIENT Viral hepatitis in the donor A hepatitis-infected individual can be used as a donor if no alternative donor is available Measures to reduce the risk of hepatitis in the recipient Treat recipients with antiviral agents: interferon, lamivudine, famciclovir Treat donors with antiviral therapy before HSC collection HBV immunity can be transferred from donor to recipient Viral hepatitis in the patient Patients should be monitored after transplantation with PCR for increasing levels of viral DNA, RNA Antiviral agents can be given to suppress viral replication interferon, ribavirin 216

3 HEPATIC COMPLICATIONS IN HSCT used to exclude the remote possibility of viremia. These data would suggest that a hepatitis-infected individual can be used as a donor, if no alternative donor is available. Measures can be taken to reduce the risk of HBV infection in recipients of infected donor marrows, including treatment of the donor with one of several antiviral agents, such as interferon, lamivudine, or famciclovir, which have been shown to be effective in suppressing HBV replication (10 12). Consideration should be given to treating HbsAg/HBV DNA-positive donors with antiviral therapy before HSC collection, although there are currently no data to support this approach. It should also be noted that immunity to HBV can be transferred from anti-hbs-positive donors to uninfected HSCT recipients. There are several reports of clearance of HBV infection after transplant from anti- HBs-positive donors to HbsAg-positive recipients through adoptive immunity transfer. Prophylactic administration of HB immune globulin or active immunization of the recipient has not been successful. Hepatitis B virus infection in the patient HBV infections arise in transplantation recipients in three ways: progression of pretransplantation infection, activation of HBV from latency, or acquisition of the virus from HBV-infected donors. Although transplantation is frequently avoided or delayed in candidates with abnormal serum aminotransferases, a finding of a positive HbsAg alone is not considered a contraindication and does not confer an increased risk for VOD. However, preexisting cirrhosis or marked hepatic fibrosis does increase the risk of severe VOD and multiorgan failure. This degree of liver damage should be considered a contraindication to high-dose therapy and HSCT (9). We recommend the following evaluation for the patient found to be HbsAg positive before transplantation. First, the replication status of the virus should be determined with testing for HbeAg, anti-hbe, and quantitated HBV DNA. Patients with replicating, wild-type HBV will usually be HbsAg, HbeAg, and HBV DNA-positive. Pretransplant liver biopsy to assess for the presence of fibrosis or cirrhosis is recommended in patients with abnormal liver enzymes or clinical stigmata of chronic liver disease. Patients with active viral replication should receive prophylactic antiviral therapy. During the post-transplant period with HBV infection, specifically after the preparative regimen but before return of cellular immunity when patients are receiving immunosuppressive therapy, there is increased risk of HBV reactivation, with progressive elevations in HBV DNA levels in the blood and liver but without an alteration in serum aminotransferases. At the time of cellular immune reconstitution, particularly when immunosuppressive drugs are being tapered, a clinical flare of hepatitis may ensue and may be fatal (13,14). The risk of fatal HBV liver disease in patients who are persistently HbsAg-positive after transplantation is approximately 12%. Risk factors for an adverse outcome have not been identified, however, fatal cases may be related to infection with a precore mutant form of HBV. Patients harboring the precore mutant HBV remain HbeAg-negative despite high levels of viral replication (9). A diagnostic dilemma may arise in a transplant recipient who develops abnormal AST or ALT levels at the time of tapering of immunosuppressive drugs, because the differential may include hepatic GVHD, HBV infection, a herpesvirus infection, or drug-induced liver toxicity. In this situation, a liver biopsy is critical to try to determine the dominant process. If the biopsy does reveal characteristic changes of GVHD, then immunosuppression should be targeted to the GVHD with the effect of also suppressing the immune response to HBV infection. Antiviral therapy should be added if there is concern about viral infection because its omission will usually lead to increasing levels of viral replication, leading to a risk of flare when the immunosuppression is tapered (2). Patients at risk for HBV infection should be monitored after transplantation for increasing levels of HBV DNA. Rising levels of HBV DNA can usually be detected as early as 1 2 weeks after HCT. Antiviral agents such as ganciclovir, lamivudine, and famciclovir can be given to suppress HBV replication so that clinical hepatitis does not accompany immune reconstitution. On the basis of the liver transplantation experience, anti-hbv therapy should be continued for the long term, although the precise duration of that therapy is unknown at this time (2). Ganciclovir is not universally effective in suppressing HBV replication and is myelosuppressive. Both famciclovir and lamivudine are very effective at suppressing HBV replication, but their use has been associated with the emergence of drug-resistant variant viruses. A preemptive approach with antiviral therapy appears to be effective in preventing HBV liver disease after orthotopic liver transplantation, but has not been reported in the HSCT setting. The most appropriate antiviral strategy, drug dosage, and treatment duration are unknown at this time. Hepatitis C infection in the donor In contrast to hepatitis B, the transmission of HCV from HCV RNA-positive HSCT donors approaches 100%, with recipients becoming viremic with high viral titers within days of the HSC infusion. However, there are no recognizable clinical consequences of the HCV infection in the recipient in the weeks post-transplant, presumably because HCV requires a functioning cellular immune system to produce hepatitis. HCV is usually 217

4 ARAI ET AL. not a significant morbidity risk in the short- to mid-term of the transplant, but the long-term concern (beyond 10 years) is that HCV will lead to cirrhosis. A study of donor hepatitis status and risk of post-transplant liver disease by the European Blood and Marrow Transplantation Group (EBMT) shows that a raised alamine aminotransferase (ALT) level in the bone marrow donor, specifically ALT. 42 U/L, with or without identifiable markers for hepatitis virus infection, does significantly increase the risk of severe liver disease (severe VOD or fulminant hepatic failure) in recipients (relative risk 6.3, p ) (2). With the incidence of HSCT donors with abnormal ALT so small (9.2%), however, this observation requires further investigation. The risk of transmission of HCV from an infected donor to recipient may be reduced by pretreatment of the donor with interferon-a (IFN-a) so that serum HCV RNA is not detectable at the time of harvest (15). If time permits, it is recommended that HCV RNA-positive donors should be treated with IFN-a before stem cell harvest. The dose and duration of IFN therapy that is optimal in this setting is not known. However, administration of 3 million units, three times a week can eradicate viremia at 6 months of treatment in 29% of chronic HCV patients, with almost all responding patients having undetectable viremia by 3 months (16). IFN should be stopped at least 1 week before stem cell harvest to avoid engraftment problems in the recipient. The addition of oral ribavirin to IFN may increase the chance of eliminating viremia in the donor. HCV infection in the patient It is important to identify HCV-infected patients before transplantation so that the severity of underlying liver disease can be assessed. Hepatitis C antibody is routinely tested in transplant candidates; however, serological testing is not adequate for exclusion of HCV infection among immunocompromised patients so that at-risk individuals should be assessed with PCR for HCV RNA. Assessment of disease severity in HCV-infected patients should include serum aminotransferase levels and liver biopsy, particularly in patients in whom there is clinical suspicion of cirrhosis. If liver biopsy reveals cirrhosis or marked hepatic fibrosis, those patients should not proceed to high-dose chemotherapy and HSCT because of the high risk of severe VOD, multiorgan failure, and death. Even in the absence of cirrhosis, HCV infection can increase the risk of severe VOD when associated with AST elevation pretransplant, with relative risk of 9.6 (17). Currently, there is no effective way to treat HCV infection before transplant or in the immediate posttransplant period. IFN-a is usually contraindicated at these times because of its myelosuppressive effects and the possibility of inducing or exacerbating GVHD. Oral ribavirin has been reported to result in clearance of HCV RNA in three marrow transplant patients. The dose of ribavirin given in adults was 600 mg twice daily; between 10 days and 3 weeks before transplant and continuing though the duration of immunosuppressive therapy (4 18 months) (18). None of the patients had severe liver complications and no severe side effects of ribavirin were documented. Post-transplantation, HCV infections may arise in two ways: progression of pretransplantation infection or acquisition from an HCV-infected hematopoietic cell or blood product donor (19). If patients come to transplantation with chronic hepatitis C, serum aminotransferase levels usually normalize and levels of viremia increase after conditioning therapy. Depending on the level of immunosuppression, an asymptomatic elevation of aminotransferases is commonly seen from days 60 to 120, and it frequently coincides with the tapering of the immunosuppressive drugs used for GVHD prophylaxis (20 23). Flares of GVHD can also be seen during this time, and it may be difficult to decide whether a flare of hepatitis C or GVHD is responsible for elevated AST and ALT levels. The differentiation of these two disorders is crucial, because GVHD of the liver usually requires increased immunosuppression, whereas acute exacerbations of hepatitis C are self-limited and do not normally require specific therapy. Unless there is evidence of active GVHD in other organs, a liver biopsy should be done before a therapeutic decision is made. Fulminant immune-rebound hepatitis C has been reported only rarely following HSCT (21). A rapid rise in aminotransferase levels can be seen after cyclosporine is tapered, but usually without evidence of liver failure (23,24). If a patient in this situation develops signs of liver failure, reintroduction of cyclosporine may lead to a reduction in liver enzyme levels and lessen the hepatocellular damage related to infiltration with cytotoxic T cells. The role of antiviral agents, such as ribavirin and IFN-a, has not been defined in this circumstance. After the initial hepatitis C flare following immune reconstitution, a pattern of chronic hepatitis can be seen. Therapy directed at chronic HCV infection should be considered once the patient has ceased all immunosuppressive drugs and has no evidence of active GVHD. HGV infection HGV is a recently identified member of the flaviviridae family of viruses and shares significant homology with HCV. HGV RNA is found in 1.5 4% of routine blood donors and is readily transmitted by blood product transfusion. HGV RNA has been identified in serum of 31 65% of HSCT recipients, most likely related to transfusion of contaminated blood products. However, evidence suggests this virus is not hepatotropic and has no role in either acute or chronic liver disease, including after HSCT (6). 218

5 HEPATIC COMPLICATIONS IN HSCT TTV TTV is a single-stranded DNA virus that can be transmitted by blood transfusion. The prevalence of TTV was extremely high in transplant recipients, 60% in one series (7). However, the virus does not appear to be a significant cause of liver disease or to influence the outcome of HSCT. EARLY POST-TRANSPLANT HEPATIC COMPLICATIONS Conditioning therapy The type of conditioning therapy given for HSCT plays a role in early hepatic complications because it can influence the development of hepatic VOD. Doses of radiation therapy exceeding Gy are associated with an increased risk of VOD. The risk of VOD is significantly higher in those receiving radiation in single dose rather than fractionated dosing (25). Drugs used in the cytoablative therapy of transplant, such as busulfan and cyclophosphamide, as well as other chemotherapy agents (cytarabine, carmustine, mitomycin, 6-mercaptopurine, dacarbazine) have been implicated in the development of VOD. In addition to the preparative regimen, the regimens of GVHD prophylaxis that utilize cyclosporine and methotrexate have been associated with an increased risk of VOD (26), as well as causing direct drug-induced injury. Hepatic VOD VOD of the liver is a life-threatening regimen-related toxicity of allogeneic and autologous HSCT. The clinical and laboratory features of VOD usually begin within the first 3 weeks after HSCT. The clinical syndrome is characterized by painful hepatomegaly, jaundice, ascites, and weight gain (27 31). Patients may develop hepatorenal syndrome with intense sodium avidity, portal hypertension, and multiorgan failure. Platelet refractoriness, abnormal venous flow in both hepatic and portal veins with flow reversal on doppler and increased wedged hepatic venous pressure gradient (WHVPG) is also seen (28 33). VOD develops in 10 60% of patients after HSCT and ranges in severity from mild reversible disease to a severe syndrome associated with multiorgan failure and death (28,29,31 33). Established severe VOD has been estimated to have a mortality rate approaching 100% by day 1100 post-transplant (5). Imaging studies of the liver: These are useful for demonstrating hepatomegaly, ascites, and attenuated hepatic venous flow consistent with VOD, as well as the absence of infiltrative lesions in the liver and hepatic veins or biliary dilatation (34,35). Doppler ultrasound may demonstrate reversal of portal venous flow in advanced VOD (36,37), but is not sensitive in the early phases of the disease (34,35). Measurement of the hepatic artery resistive index may be a more sensitive marker of VOD (35). Portal vein thrombosis has been observed in patients with VOD, probably a reflection of portal venous stasis and of a procoagulant state (38). Liver biopsy and intrahepatic pressure measurements: In cases where the diagnosis is unclear, a transvenous approach that allows both biopsy and hepatic venous pressure measurements has proved useful (39,40). Unfortunately, use of the transjugular biopsy is not standardized across institutions. Transvenous approaches with different equipment have been described (Mansfield forceps, manual and automated Cook needles) (39 41). The consensus appears to be that the transjugular approach is safe and provides adequate histology for diagnosis, as compared with the percutaneous or laparoscopic needle biopsy methods which carry a high risk of bleeding in the thrombocytopenic patient (42). Transvenous biopsy also allows for hepatic venous pressure gradient determination, which has reported utility in diagnosing VOD. A gradient higher than 10 mmhg is highly specific (.90%) and moderately sensitive (60%) for VOD (39,40). Higher pressure gradients correlate with a worse prognosis. A striking result from our institution s experience with transjugular liver biopsy has been that its use has helped show how clinical signs alone cannot be relied upon to determine the etiology of hepatic dysfunction post-transplant. In 65% of cases, liver biopsy was helpful in clarifying the differential for hepatic dysfunction. At our institution, the transjugular liver biopsy is incorporated as the standard approach in a critical pathway of post-transplant hepatic dysfunction. VOD is thought to be caused by injury to the sinusoidal endothelial cells and hepatocytes in zone 3 of the liver acinus, eventually progressing to central vein occlusion with deposition of collagen in the sinusoids, sclerosis of venular walls, and fibrosis of venular lumens (28,43 45). A procoagulant state is present, characterized by low plasma levels of antithrombin III and protein C, consumption of factor VII, and increased levels of plasminogen activator inhibitor 1 (PAI-1) (29,46 49). In addition, increased levels of von Willebrand factor (vwf) multimers and refractoriness to platelet transfusions are seen in VOD, suggesting further activation of the coagulation cascade with ongoing endothelial injury (46). Potential VOD therapies: Although the pathophysiology of VOD remains incompletely understood, antithrombotic and thrombolytic agents including prostaglandin E1 and tissue plasminogen activator (tpa) with or without concurrent heparin have been evaluated for 219

6 ARAI ET AL. the treatment of VOD (29,50,51). However, these approaches have been limited by significant toxicity, including fatal hemorrhage (29,50,52). Even with best supportive care and the addition of interventions such as tpa/heparin, the outcome of patients with severe VOD has remained uniformly very poor (52). Furthermore, efficacy has been difficult to establish in these patients and as a result no therapies for VOD have been evaluated in a prospective, randomized fashion. Defibrotide: Defibrotide (DF) is a polydeoxyribonucleotide derived from mammalian tissue and has been found to have antithrombotic, anti-ischemic, anti-inflammatory, and thrombolytic properties without significant systemic anticoagulant effects (53). DF has a complex mechanism of action. It is an adenosine receptor agonist with affinity for receptors A1 and A2 via aptameric activity which results in thrombin antagonism in vitro (54,55). DF also increases levels of endogenous prostaglandins (PGI2 and E2), reduces levels of leukotriene B4, inhibits monocyte superoxide anion generation, stimulates expression of thrombomodulin in human vascular endothelial cells, modulates platelet activity, and stimulates fibrinolysis by increasing endogenous tpa function while decreasing activity of PAI-1 (56 60). The lack of significant systemic anticoagulant activity suggests that DF may have a therapeutic advantage over the use of tpa and heparin. DF also appears to be well tolerated. Adverse events are mild, range in incidence from 1% to 9%, and include flushing, transient mild systolic hypotension, nausea, and abdominal discomfort (53). Preliminary evidence for the use of DF in VOD comes from a study of 19 patients who developed severe VOD with multiorgan dysfunction following stem cell transplant (61). Treatment was begun at a median of 6 days after diagnosis of VOD. DF was administered intravenously in doses ranging from 5 to 60 mg/kg per day for a minimum course of 14 days. In no case was DF discontinued for attributable toxicity. No severe hemorrhage related to DF administration was seen. Resolution of VOD (bilirubin,2 mg/dl with improvement in other related symptoms and signs) was seen in 8/19 (42%) and 6/8 responders who survived past day Given that the predicted survival of comparable patients has been reported to be 2%, the observed 32% survival at day 1100 and the absence of significant DF treatment-related toxicity are encouraging. A randomized, dose-finding trial is now underway to further evaluate the role of DF. Antithrombin III: Antithrombin III (AT-III) concentrate has been used in patients with VOD who have documented deficiency of AT-III. In one report, 10 patients with severe VOD and AT-III levels less than 88% or normal were treated with AT-III at a loading dose of 50 units/kg every 8 h for three doses, followed by 50 units/kg per day for 3 12 days (62). All patients achieved clinical improvement. The combination of tpa and continuous infusion AT-III has also been reported to have clinical efficacy in children (63). Antioxidant therapy: Free radical damage occurring as a component of VOD can result in glutathione antioxidant depletion. Glutamine infusion in animal studies has been shown to maintain glutathione levels. In one report, 2 patients with VOD were successfully treated with intravenous glutamine and oral vitamin E, suggesting there may be a role for antioxidant therapy in the prophylaxis and treatment of VOD (64). Transjugular intrahepatic portosystemic shunt and liver transplantation: Transjugular intrahepatic portosystemic shunt (TIPS) has been performed in small numbers of patients with VOD with reports of regression of the hepatic and renal symptoms. Patients with milder disease appear more likely to respond, making TIPS a limited option. Similarly, orthotopic liver transplantation has been successfully performed in small numbers of patients with VOD, however, few severe VOD patients are likely eligible to undergo such rigorous surgery. Prevention efforts for VOD: Without specific, effective therapy, prophylaxis against VOD is a logical approach. Protocols using ursodeoxycholic acid (UDCA) and heparin have been used with limited success. UDCA used prophylactically has been shown to reduce the incidence of VOD in a pilot study and subsequent randomized controlled trial. In the controlled trial, 67 patients undergoing allogeneic HSCT with cyclophosphamide and busulfan induction and cyclosporine/ methotrexate GVHD prophylaxis were given UDCA prophylaxis (300 mg BID or 300 mg qam and 600 mg qpm) versus placebo. The incidence of VOD was significantly lower in patients randomized to UDCA (15 versus 40%, p ). Some centers use UDCA routinely for the prevention of VOD. The efficacy of low-dose heparin, unfractionated or low molecular weight, as VOD prophylaxis has not been confirmed in all series, and therefore is not a recommended prophylaxis at present. Gallbladder and biliary disease Biliary sludge syndrome: Biliary sludge can be demonstrated by ultrasound as low-amplitude echogenic material without acoustic shadowing that layers in the gallbladder and shifts with positioning (65,66). Biliary sludge formation is common, occurring in approximately 70% of patients followed prospectively. Risk factors for sludge formation after HSCT include prolonged fasting and TPN (67), antibiotic treatment, narcotic administration, and endothelial injury from condi- 220

7 HEPATIC COMPLICATIONS IN HSCT tioning therapy or GVHD. Biliary sludge may be a cause of acute acalculous cholecystitis (68) and acute pancreatitis (69,70) and may result in nonvisualization of the gallbladder on scintigraphy (71). Acute bacterial cholangitis due to biliary sludge has also been reported. Disorders of the gallbladder: Acute cholecystitis is seen in HSCT recipients (71), and, when it does occur, is frequently not associated with the presence of gallstones (72,73). Acalculous cholecystitis in this setting may be due to leukemic relapse with gallbladder involvement (74), cytomegalovirus (CMV) (75), or fungal (76) infection, or biliary sludge. Patients experience right upper quadrant pain and tenderness but may not have associated nausea, vomiting, hyperbilirubinemia, or leukocytosis (73). Diagnosis is difficult because of the high frequency of gallbladder abnormalities seen by biliary sonography following HSCT (73). Pericholecystic fluid, gallbladder wall necrosis, and localized tenderness when the transducer is pressed over the gallbladder suggests cholecystitis. In the absence of these findings, a hepatic iminodiacetic acid (HIDA) scan is useful; nonvisualization of the gallbladder suggests cholecystitis (77). Patients with suspected cholecystitis can be managed with cholecystectomy. Medications and total parenteral nutrition: Oral nonabsorbable antibiotics (particularly nystatin), cyclosporine, mycophenolate mofetil, trimethoprim-sulfamethoxazole (TMP-SMX), intravenous amphotercin, and high-dose opioids are frequent causes of drug-induced cholestasis. Total parenteral nutrition (TPN) is associated with significant hepatobiliary disease, which includes hepatic steatosis and intrahepatic cholestasis associated with periportal inflammation. TPN also induces extrahepatic biliary disease. After 3 weeks of TPN, sludge begins to appear; between 4 and 6 weeks, 50% of patients develop gallbladder sludge, and, after 6 weeks, 100% of patients have sludge (67). Sludge arises from reduced gallbladder contractility that occurs in the fasting state and predisposes to significantly higher rates of both calculous and acalculous cholecystitis in patients on longterm TPN compared to those with oral intake (78). Gallstones that arise in the setting of TPN are composed of calcium bilirubinate as opposed to the cholesterol that typifies stones occurring in other settings. Early cholecystectomy has been suggested to prevent potentially complicated acute cholecystitis in patients requiring longterm TPN, although it is rarely performed prophylactically (79). The accumulation of gallbladder sludge is reversible 4 weeks after the resumption of oral intake (67). HCT patients often require long-term TPN because oral intake is impossible. HSCT patients often develop severe nausea and vomiting, mucositis as a result of drug toxicity, or agvhd. In addition, these patients have rapid red blood cell turnover and multiple blood transfusions, which may further predispose them to developing bilirubinate gallstones. Finally, narcotics, which are used frequently in this population, further impair gallbladder contractility by raising intraluminal pressure in the bile ducts and gallbladder. Allogeneic HSCT patients at our institution tend to receive TPN for an average of 14 days (range 4 22). Sixtyseven percent of the transplant recipients develop gallbladder sludge early in their course, thus potentially placing them at risk for more serious extrahepatic biliary disease (80). These results are similar to the Seattle studies (71,80), which show that gallbladder sludge developed in approximately 70% of patients within 4 weeks of HCT. Moreover, gallstones were found in approximately 20% of patients within 4 weeks of BMT. Prevention of gallbladder disease is highly desirable in this group of patients, because they tend to be poor surgical candidates due to their immunocompromised states and thrombocytopenia. Furthermore, our transplant patients who developed acute cholecystitis within the first 60 days of transplant, had a worse outcome than those HCT patients who developed it later in their course. The presence of gallbladder sludge or stones makes it difficult to determine the cause of abnormal liver function tests, because HSCT patients are at risk for hepatic diseases such as GVHD, VOD, and drug hepatotoxicity. Invasive tests to discern the precise etiology of hepatic dysfunction place this patient group at further risk for procedure-related complications and are often avoided. Therefore, alternative strategies are needed to prevent biliary complications in HCT patients. Few clinical studies have been done in humans investigating the prokinetic treatment of biliary disease. There is a report that cholecystokinin-octapeptide (CCK-OP) has been used successfully to increase gallbladder contractility in surgical patients on long-term TPN (81,82). In a randomized controlled study (81), CCK-OP was administered as a daily intravenous infusion into 7 patients, whereas saline was administered to 8 control patients. After an average period of 4 weeks, none of 7 patients receiving CCK-OP developed gallbladder sludge, but 5 of 8 patients who received saline did. CCK-OP was well-tolerated with minimal side effects mild abdominal cramping occurred in 2 patients. Given these results, CCK-OP may be useful for the prevention of gallbladder disease in the HCT setting as well. Prevention of gallbladder sludge formation by increasing gallbladder contractility may prevent complications related to extrahepatic biliary disease. Extrahepatic biliary obstruction Causes of obstruction after HSCT include lymphoblastic infiltration of the common bile duct and gall- 221

8 ARAI ET AL. bladder in Epstein-Barr virus (EBV) lymphoproliferative disease, CMV-related biliary disease, dissecting duodenal hematoma complicating endoscopic biopsy, inspissated biliary sludge in the distal common bile duct, and leukemic relapse (chloroma) in the head of the pancreas and distal common bile duct (83). In transplant recipients, it is impossible to distinguish between extrahepatic biliary obstruction and cholestatic liver disease on clinical and laboratory grounds. Ultrasound examination of the gallbladder to exclude bile duct dilatation is recommended in any transplant recipient with severe progressive cholestasis. Infections of the liver Fungal infections: Tender hepatomegaly in a candidate for HSCT suggests either fungal infection or tumor in the liver. The diagnosis of malignant cells in the liver is often secondary, because there is usually evidence of tumor elsewhere. However, patients harboring fungi in the liver do require diagnosis with liver biopsy. Candida species are the most common cause of fungal abscesses in the liver (84), but with the widespread use of triazole antifungal, prophylaxis with fluconazole has dramatically reduced the incidence of infections with most Candida species. However, infection with triazole-resistant Candida species, C. krusei and C. glabrata, has increased, probably as a result of prophylaxis. Infection with Aspergillus may involve the liver but is usually associated with clinically apparent infection at other sites, particularly the lungs (84,85). Disseminated infection that may involve the liver has been described in other fungi, including Scopulariopsis, Trichosporon, Pseudallescheria, Coniothyrium, Fusarium, Mucor, Absidia, and Dactylaria species (84,85). The symptoms of fungi in the liver include fever, tender hepatomegaly, and increased serum alkaline phosphatase levels (86). However, these findings are also common to many liver diseases after transplantation. Imaging tests, such as CT scan or ultrasound, are used for diagnosis of fungal liver lesions, although these modalities are less sensitive for small, miliary fungal lesions typically found in transplant patients. Magnetic resonance imaging (MRI) may be more sensitive. Rarely, fungi can invade vascular structures, resulting in hepatic infarcts or venous obstruction mimicking VOD (86). Massed fungi causing bile duct obstruction have also been described (87,88). The diagnosis of fungal liver infection in a patients with negative findings on an imaging test may be based on a consistent clinical picture in a patient with risk factors (positive blood culture, colonization, severe liver dysfunction) (84). Liver biopsy with special stains and cultures can help to confirm invasive liver disease. Restoration of granulocyte counts is the single most important factor in recovery from fungal liver infection. Bacterial infections: In HSCT patients, fevers of undetermined origin and bacteremias are treated rapidly with antibiotics. Reactivation of latent mycobacterial infection within the liver may occur with prolonged immunosuppressive therapy (89). Disseminated BCG infection with marrow, liver, and spleen involvement has been reported (89,90). Diagnosis of mycobacterial liver infection requires liver biopsy, cultures, and the appropriate stains. Viral infections: Reactivation of viral infections, such as CMV, herpes simplex virus (HSV), human herpesvirus-6 (HHV-6), adenovirus, and varicella zoster virus (VZV), typically occurs in the early post-engraftment period. Acute GVHD is a significant risk factor for these viral diseases, which can be disseminated involving the liver and cause widespread necrosis and hepatic failure (91). Liver biopsy with viral culture and PCR are useful in making a diagnosis in this setting. Patients with HSV and VZV infection should be treated with acyclovir. Prophylaxis with acyclovir fortunately has markedly reduced the incidence of all herpetic infections in transplant recipients. For adenovirus infection, the most effective agent appears to be intravenous ribavirin, with reports of clinical improvement and viral clearance in both single-organ and disseminated infection (2). Preemptive antiviral therapy with ganciclovir in the case of CMV disease has markedly reduced the incidence and severity of the disease and delayed its onset from a median of eight weeks to greater than three months. EBV may produce a clinical hepatitis or a polymorphic B cell lymphoma in immunodeficient patients. The median time to onset of EBV lymphoma is later in the transplant course, about days post-transplant. Liver involvement occurs in over 50%, manifested by abnormal alkaline phosphatase levels and massive hepatosplenomegaly. Liver biopsy reveals the diagnosis, along with confirmatory studies of in situ hybridization and immunohistochemistry for EBV-specific markers. Adoptive immunotherapy by infusion of peripheral blood mononuclear cells from the EBV-seropositive donor, or of in vitro-expanded EBV specific T-cells can result in complete remission in recipients with T celldepleted stem cells, but the disease is usually fatal when it occurs in the setting of GVHD and high-dose immunosuppression (2). agvhd of the liver Liver involvement with GVHD usually manifests as cholestatic jaundice without a high incidence of hepatocellular failure. The diagnosis of liver GVHD is often uncertain, given the differential of chronic hepatitis in the SCT patient population who are multiply transfused, hepatic VOD, and viral infections. 222

9 HEPATIC COMPLICATIONS IN HSCT Clinical presentation: Increased serum alkaline phosphatase is followed by hyperbilirubinemia, mild hepatomegaly, and clinical jaundice. Usually both skin and intestinal manifestations of GVHD are apparent by the time jaundice is noted, although liver involvement may be the presenting feature. Features of severe hepatocellular dysfunction such as prolongation of the prothrombin time and encephalopathy are terminal manifestations of liver failure in patients with prolonged severe multisystem GVHD (2). Hypoalbuminemia is not usually due to severe liver disease, but rather to intestinal protein loss and negative nitrogen balance (2). Diagnosis and histopathology: Liver biopsies via the transjugular approach are strongly suggested to document the presence of GVHD, particularly with the possibility that other etiologies can account for the hepatic dysfunction, including hepatic VOD, hepatic infections, conditioning regimen toxicity, and GVHD prophylaxis regimen (cyclosporine, methotrexate) toxicity. Histologic confirmation of GVHD helps to sort out the multiple etiologies, and guide therapy. Corticosteroid is still the firstline and most effective treatment option for acute GVHD. The most commonly used corticosteroid is methylprednisolone at a dose of mg/kg per day in divided doses. Nonresponders at day 5 may be treated with high dose steroids (10 mg/kg per day). If patients then respond, the steroid dose is lowered to mg/kg per day with gradual taper. If the high-dose steroid is not successful in controlling GVHD, salvage treatments are introduced, such as tacrolimus, antithymocyte globulin, and mycophenolate mofetil, although with less success. From Seattle data regarding salvage therapy, improvement or resolution of GVHD by respective organs was best with skin disease (45%), followed by gut disease (35%), and worst with liver disease (25%). With growing understanding of the pathogenesis of GVHD, more targeted organ therapies are being developed. Potential therapies targeting liver GVHD include the antioxidant N-acetylcysteine with its action on reducing interleukin-2 (IL-2) levels. Hepatocyte growth factor has an encouraging profile, with its antiapoptotic effect on donor T cell infiltration in the liver, as well as its action on suppressing IFNg tumor necrosis factor-a (TNF-a) expression, and IL-12 levels in GVHD mouse models. LATE HEPATIC COMPLICATIONS Chronic hepatitis B A minority of HSCT survivors infected with HBV have progressive inflammatory liver disease leading to liver failure 1 3 years after transplantation. The serological pattern of HBV infection may be atypical in transplant survivors, probably as a consequence of immunosuppression. Clearance of antigenemia is commonly observed and is particularly likely if the donor was anti- HBs positive (92,93). Once they are stable and off all immunosuppression, long-term survivors who remain HBsAg positive generally exhibit only mild liver disease (94). However, in the presence of chronic GVHD, and a requirement for immunosuppressive drugs, patients with chronic HBV infection remain at risk for acute flares of hepatitis whenever immunosuppression is tapered or stopped (95). Cirrhosis due to HBV infection has not emerged as a major problem in long-term survivors, although this may be due to an inadequate period of follow-up. Chronic hepatitis C Hepatitis C infection in long-term HSCT survivors commonly results in fluctuating serum aminotransferase levels. Cirrhosis is emerging as an important late complication of HSCT in the second and third decade posttransplant (9). These patients are frequently asymptomatic without features of portal hypertension or liver failure, but over the long-term, have developed liver failure requiring liver transplantation, and some have died with hepatocellular carcinoma. Consideration should be given to preventative treatment of chronic hepatitis C infection in HSCT survivors because these patients appear to have a more accelerated course to cirrhosis than do other populations infected with HCV. IFN-a can be safely administered to patients who have been off all immunosuppressive agents for at least 6 months and have no evidence of GVHD or myelosuppression. Response rates to IFN-a appear no different from those seen in nontransplant patients with hepatitis C, so that overall sustained biochemical responses can be expected to be about 23% in treated patients and sustained viral responses, about 8% (96). In nontransplant patients, the combination of oral ribavirin with IFN-a has resulted in sustained virologic response rates of 40 50% and, therefore, can be considered for HSCT survivors. In patients with iron overload and chronic hepatitis C, chelation therapy or phlebotomy to reduce hepatic iron stores should be considered prior to IFN therapy and may increase the chance of response. Iron overload Hemosiderosis of the liver is found in approximately 90% of long-term survivors of transplantation for hematologic malignancies and related to a combination of multiple red-cell transfusions and dyserythropoiesis. An elevated serum ferritin level is a reliable indicator of increased tissue iron stores in the stable patient without ongoing disease (97). However, in the presence of other 223

10 ARAI ET AL. disease processes, such as GVHD and viral hepatitis, a liver biopsy may be required to quantitate hepatic iron stores accurately. The consequences of tissue iron overload in transplant survivors are not clearly established. It has been suggested that iron overload may be a cause of persistent hepatic dysfunction after HSCT (98,99) from free radical lipid peroxidation of membranes and intracellular iron accumulation. Concurrent chronic HCV infection may be a major contributor to the liver disease, because iron overload may worsen the natural history of hepatitis C disease. In addition, the risk of opportunistic infections is increased in patients with hepatic iron overload. Long-term survivors should be assessed for iron overload, and phlebotomy or chelation therapy should be considered in those with documented significant iron overload (99,100). cgvhd of the liver Hepatic involvement with chronic GVHD is common, occurring in 80% of extensive disease patients, frequently following acute liver GVHD (2). Patients present mainly with cholestasis, an elevated serum alkaline phosphatase, and elevated bilirubin. The degree of hyperbilirubinemia, however, does not correlate with the severity of the disease. Patients may have hyperbilirubinemia regardless of improvement or deterioration of liver function. Liver biopsy frequently shows lobular hepatitis, chronic persistent hepatitis, chronic active hepatitis, and loss of small bile ducts with cholestasis. Clinical course and treatment: The treatment of chronic GVHD is determined in part by the severity of the disease. Higher-risk chronic GVHD tends to have evidence of hepatic dysfunction, particularly with serum bilirubin concentrations greater than 1.2 mg/dl (hazard ratio for death of 2.1). First-line therapy for chronic GVHD is administration of immunosuppressive medications, prednisone alone if no high-risk features, or prednisone plus cycloporine for high-risk disease, along with infection prophylaxis. Response of alkaline phosphatase level may be expected within 2 4 weeks of starting immunosuppressive therapy, but may not return entirely to normal unless there is complete improvement in other target organs. Treatment is often prolonged. A flare of chronic GVHD after stopping immunosuppression may be manifested by increasing alkaline phosphatase levels. Newer immunosuppressive agents, tacrolimus, rapamycin, and mycophenolate mofetil, have been introduced as prophylaxis and therapy of chronic GVHD, with preliminary efficacy. Ursodeoxycholic acid (UDCA) has also shown transient drops in serum bilirubin, alkaline phosphatase, and AST levels in refractory liver GVHD patients, but longterm efficacy is unlikely because it works by preventing further bile salt damage. More challenges to management of chronic GVHD were presented recently by Strasser et al. (101), who described a patient series where the clinical presentation of chronic GVHD of the liver was significantly different from the typical clinical picture. In these patients, there was sudden onset of jaundice, accompanied by marked elevation in serum aminotransferases suggestive of acute hepatitis. Liver biopsy was important in confirming the diagnosis of GVHD. This presentation of hepatic chronic GVHD appears to be the GVHD manifestation in patients who are off or on minimal immunosuppression at the onset of GVHD. The patients do respond to high-dose immunosuppressive therapy with progressive improvement and normalization of liver enzymes and bilirubin. There is histological similarity with that of acute liver allograft rejection; however, the pathophysiology may be different. The lack of background immunosuppression may exaggerate Fas Fas ligand interactions, TH1 cell activation, cytokines, and other effector cells. Knowledge of these various clinical manifestations of chronic liver GVHD will help to identify those patients with poor outcome who will benefit from more aggressive treatment regimens. TABLE 3. DIFFERENTIAL DIAGNOSIS OF HEPATIC DYSFUNCTION IN HSCT Pre-transplant Pre-existing liver disease hepatitis B or C in the donor or recipient Pre-engraftment to,3 weeks post transplant Bacteria, herpes simplex virus, chronic disseminated candidiasis Hepatic veno-occlusive disease (VOD) Drug toxicity from GVHD prophylaxis regimen Conditioning regimen Early post-engraftment, from 3 weeks to 3 months Conditioning regimen VOD HSV, CMV, HHV-6, VZV, chronic disseminated candidiasis Drug toxicity, TPN Gallbladder disease Acute GVHD Hepatitis B, C viruses EBV Late post-engraftment,.3 months Hepatitis B, C virus Drug toxicity Chronic GVHD Iron overload 224