Bicalutamide is a nonsteroidal antiandrogen similar in structure to flutamide that is used widely in the therapy of prostate cancer and has been linked to rare instances of liver injury.
Bicalutamide (bye" ka loo' ta mide) is an orally available nonsteroidal antiandrogen that is similar in structure to flutamide and nilutamide. Bicalutamide acts by binding to intracellular androgen receptors and competitively inhibiting the action of endogenous androgens on sensitive tissue, including testes, prostate, breast, skin and hypothalamus. Bicalutamide was approved for use in the United States in 1995. Current indications are for the therapy of prostate cancer in combination with luteinizing hormone releasing hormone (LHRH) analogs such as leuprolide or goserelin. Bicalutamide is available in tablets of 50 mg generically and under the trade name of Casodex. The recommended dose is 50 mg once daily. Common side effects of bicalutamide include fatigue, drowsiness, anxiety, gynecomastia and loss of libido.
Bicalutamide therapy is associated with mild, asymptomatic and transient elevations in serum aminotransferase levels in approximately 6% of patients. The frequency and height of the ALT elevations appears to be less with bicalutamide than flutamide. Similarly, there have been rare case reports of clinically apparent liver injury due to bicalutamide, but less frequently than with flutamide. In the Spanish pharmacovigilance study, there were 11 reports of hepatotoxicity from bicalutamide, none of which were fatal. On the other hand, the product label for bicalutamide mentions that a few cases of fatal hepatic failure have been reported. The clinical pattern of liver injury with bicalutamide appears to resemble that of flutamide. The latency to onset is usually 2 to 3 months, but can be shorter with reexposure and occasionally arises 4 to 6 months after starting. The typical pattern of serum enzyme elevations is hepatocellular and severe, fulminant cases have been described. Rash, fever and eosinophilia are not common and autoantibody formation is not described.
Likelihood score: B (likely cause of clinically apparent liver injury).
Mechanism of Injury
The mechanism of bicalutamide hepatotoxicity is unknown. It is metabolized by the liver via the cytochrome P450 system, largely via CYP 3A4 which it can inhibit and thus cause drug-drug interactions. Thus, liver injury from bicalutamide may be caused by toxic metabolites of the agent. The lower frequency of hepatotoxicity from bicalutamide compared to flutamide may be due to its lower dose or its lower rate of hepatic metabolism.
Outcome and Management
The mild ALT elevations during bicalutamide therapy are usually self-limiting even with continuation of the medication. The rare instances of clinically apparent liver injury have ranged in severity from mild self-limiting cases to fatal acute liver failure. Monitoring of liver tests during therapy is recommended. There is no information on cross sensitivity to hepatic injury among the various antiandrogens. Rechallenge should be avoided and switching therapy to flutamide or nilutamide cannot be recommended.
Case 1. Acute liver failure arising after two doses of bicalutamide.
[Modified from: Dawson LA, Chow E, Morton G. Fulminant hepatic failure associated with bicalutamide. Urology 1997; 49: 283-4. PubMed Citation]
A 60 year old man with prostate cancer developed acute liver failure following two doses of bicalutamide and a few days after stopping a 3 month course of flutamide. Liver test results were reported to be normal at the time of diagnosis of prostate cancer. Following an initial month of therapy with cyproterone acetate, flutamide and monthly subcutaneous goserelin acetate was started. Although flutamide was well tolerated, it was discontinued after 3 months and bicalutamide was substituted. After the second dose of bicalutamide, the patient developed jaundice and confusion. All medications were stopped and he was admitted for evaluation and therapy. He had no previous history of liver disease, no risk factors for viral hepatitis and no recent use of alcohol or acetaminophen. Serum bilirubin was 19.5 mg/dL, and serum ALT was markedly elevated with minimal increase in alkaline phosphatase levels (Table). The INR was 2.2. Tests for hepatitis A, B, C and for EBV infection were negative as were autoantibodies. An abdominal ultrasound revealed no evidence of biliary disease or liver metastasis. The patient developed mental obtundation and required intensive care support, vitamin K, and lactulose. After an initial period of worsening, he improved slowly. Eight weeks later, serum enzymes and bilirubin levels were normal.
|| Bicalutamide, 50 mg, 2 doses, and flutamide, 750 mg daily for 3 months
|| 4+ (jaundice, hospitalization, coagulopathy and encephalopathy)
|| 2 days for bicalutamide, 3 months for flutamide
|| 2 months
|| Flutamide, cyproterone acetate, goserelin acetate
|Time After Starting
||Time After Stopping
||Alk P (U/L)
|Bicalutamide 50 mg daily for two days
Although widely cited as an example of bicalutamide hepatotoxicity, this case can only be said to be “possibly” related to bicalutamide and is much more likely due to flutamide hepatotoxicity with the typical abrupt hepatocellular pattern of injury arising after 3 months of therapy. Indeed, even with the most severe hepatic injury (in the absence of hemolysis), it would take more than 2 days for serum bilirubin to rise from normal to 19 mg/dL. Cyproterone has also be linked to similar cases of hepatocellular injury, but the appearance of jaundice several months after stopping this agent, makes it unlikely as the cause.
REPRESENTATIVE TRADE NAMES
Bicalutamide – Generic, Casodex®
Product labeling at DailyMed, National Library of Medicine, NIH
||CAS REGISTRY NO
References updated: 05 July 2017
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Dawson LA, Chow E, Morton G. Fulminant hepatic failure associated with bicalutamide. Urology 1997; 49: 283-4. PubMed Citation (60 year old man with prostate cancer was given cytoproterone and flutamide for 3 months and then switched to bicalutamide developing jaundice after 2 doses [bilirubin 19.5 mg/dL, ALT 2690 U/L, Alk P 181 U/L, INR 2.2 and encephalopathy], improving within 2 months: Case 1).
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Palmberg C, Kylmala T, Tammela T. Reduction of flutamide-induced alanine aminotransferase elevation after replacement by bicalutamide in a patient with N+ disease treated with maximal androgen blockade as a primary treatment. Br J Urol 1997; 79: 808-9. PubMed Citation (46 year old man with prostate cancer developed ALT elevations [106 U/L] without jaundice after 21 months of flutamide [750 mg/day], which improved on stopping [to 73 U/L] and increased again [108 U/L] with restarting [500 mg/day]. Switching to bicalutamide [50 mg/day] was followed by decrease of ALT but not to normal [53 U/L]).
Tyrrell CJ, Kaisary AV, Iversen P, Anderson JB, Baert L, Tammela T, Chamberlain M, et al. A randomised comparison of 'Casodex' (bicalutamide) 150 mg monotherapy versus castration in the treatment of metastatic and locally advanced prostate cancer. Eur Urol 1998; 33: 447-56. PubMed Citation (European trial of bicalutamide vs orchiectomy in 1453 men with prostate cancer, found bicalutamide monotherapy less effective; no mention of serious adverse events or hepatotoxicity).
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Manso G, Thole Z, Salgueiro E, Revuelta P, Hidalgo A. Spontaneous reporting of hepatotoxicity associated with antiandrogens: data from the Spanish pharmacovigilance system. Pharmacoepidemiol Drug Saf 2006; 15: 253-9. PubMed Citation (Analysis of spontaneous reporting to Spanish Pharmacovigilance system found 88 cases of flutamide, 11 bicalutamide and 15 cyproterone hepatotoxicity, latency 3-6 months; 2 fatalities, both from flutamide).
Castro Beza I, Sánchez Ruiz J, Peracaula Espino FJ, Villanego Beltrán MI. Drug-related hepatotoxicity and hepatic failure following combined androgen blockade. Clin Transl Oncol 2008; 10: 591-2. PubMed Citation (61 year old man with prostate cancer developed jaundice 3 months after starting bicalutamide [bilirubin 11.5 mg/dL, ALT 1923 U/L, Alk P 169 U/L], and subsequently developed progressive liver failure and died).
O'Bryant CL, Flaig TW, Utz KJ. Bicalutamide-associated fulminant hepatotoxicity. Pharmacotherapy 2008; 28: 1071-5. PubMed Citation (59 year old man with prostate cancer developed abdominal pain 4 days after restarting bicalutamide [bilirubin not given, ALT 111 rising to 2050 U/L, INR 3.4], which was followed by multiorgan failure and death in 4 days).
Chalasani N, Fontana RJ, Bonkovsky HL, Watkins PB, Davern T, Serrano J, Yang H, Rochon J; Drug Induced Liver Injury Network (DILIN). Causes, clinical features, and outcomes from a prospective study of drug-induced liver injury in the United States. Gastroenterology 2008; 135: 1924-34. PubMed Citation (Among 300 cases of drug induced liver disease in the US collected between 2004 and 2008, none were attributed to an antiandrogen).
Reuben A, Koch DG, Lee WM; Acute Liver Failure Study Group. Drug-induced acute liver failure: results of a U.S. multicenter, prospective study. Hepatology 2010; 52: 2065-76. PubMed Citation (Among 1198 patients with acute liver failure enrolled in a US prospective study between 1998 and 2007, 133 were attributed to drug induced liver injury, but none were attributed to antiandrogen therapies).
Chalasani N, Bonkovsky HL, Fontana R, Lee W, Stolz A, Talwalkar J, Reddy KR, et al.; United States Drug Induced Liver Injury Network. Features and outcomes of 899 patients with drug-induced liver injury: The DILIN Prospective Study. Gastroenterology 2015; 148: 1340-52.e7. PubMed Citation (Among 899 cases of drug induced liver injury enrolled in a US prospective study between 2004 and 2013, 1 case [0.1%] was attributed to bicalutamide: 50 year old man with prostate cancer developed jaundice 4 months after starting bicalutamide [bilirubin 3.4 mg/dL, ALT 2412 U/L, Alk P 147 U/L, INR 1.2] with slow but complete resolution upon stopping).
Yun GY, Kim SH, Kim SW, Joo JS, Kim JS, Lee ES, Lee BS, et al. Atypical onset of bicalutamide-induced liver injury. World J
Gastroenterol 2016; 22: 4062-5.
PubMed Citation (62 year old man with prostate cancer developed jaundice 19 weeks after starting bicalutamide [biirubin 1.6 mg/dL, ALT 677 U/L, Alk P 87 U/L, INR 1.17], resolving completely within 3 months of stopping).
Hussain S, Haidar A, Bloom RE, Zayouna N, Piper MH, Jafri SM.
Bicalutamide-induced hepatotoxicity: A rare adverse effect. Am J Case Rep 2014; 15: 266-70. PubMed Citation (81 year old man with prostate cancer developed jaundice 3 weeks after starting bicalutamide [bilirubin 3.7 mg/dL, ALT 576 U/L, Alk P 223 U/L, INR 1.5], which improved rapidly after stopping).