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Fecal DNA Testing for Colorectal Neoplasia in IBD: Could it be as Simple as a Stool Study?
August 2013
SELECTED SUMMARIES 479
can cause weight loss and may have anti-inflammatory effects. Furthermore only 1 measurement of BMI was analyzed when subjects were recruited, which may have been several years before diagnosis, and it is conceivable that BMI closer to diagnosis is more predictive of incident IBD. However, data from 1 cohort in the study suggested only a minimal weight gain of 1.5 kg from recruitment to a mean follow-up of 3.7 years. Although the authors of this study found no association between obesity and development of IBD, they note that only BMI was studied as a measure of obesity, which has a poor linear relationship with total body fat. Alternative measures of adiposity may have more prognostic value, such as waist-to-hip ratio, which is a more accurate marker of central obesity and visceral fat. Furthermore recent studies have suggested that mesenteric fat deposition rather than subcutaneous fat is a primary contributor to inflammation in CD (Gut 2012;61:78–85). Future studies using novel methods to evaluate fat stores, including visceral, subcutaneous, and mesenteric deposits, may help to determine whether obesity is a risk factor for the development of IBD. The developing field of analytic morphometrics, which uses measurements based on imaging to evaluate anatomic features that may predict medical outcomes, could provide answers. A recent study using analytic morphomics found that abdominal subcutaneous fat is an independent predictor of surgical site infections, and that subcutaneous fat improved model predictions of surgical site infections compared with BMI (J Am Coll Surg 2011;213:236–244). That same methodology, when applied to obesity and IBD, may provide more nuanced answers by evaluating specific fat storage deposits and their association with incident IBD. Obesity has been linked with the development of other inflammatory conditions, such as rheumatoid arthritis, which has risen in incidence and prevalence in recent years. Analysis of a cohort from Olmsted County, Minnesota, suggested that obesity accounted for 52% of the increased risk for developing rheumatoid arthritis between 1985 and 2007 (Arthritis Care Res 2013;65:71–77). Creeping fat, recognized for decades as a marker of CD activity, may be a source of disease-promoting adipokines, and is correlated with muscular hypertrophy, fibrosis, and stricturing (Inflamm Bowel Dis 2012;18:1550–1557). The cytokine milieu, which is a byproduct of fat stores, may be associated with development of CD and other inflammatory conditions, such as rheumatoid arthritis. In the end, this large, prospective, cohort study with extended follow-up found no association between incident IBD and obesity as measured by BMI. With the rising incidence of IBD and widespread adoption of Western dietary habits, examination of more nuanced measures of adiposity such as waist-to-hip ratio and mesenteric fat may provide further clarity (Gastroenterology 2013;144[suppl 1]:S-87). JOSHUA B. MAX RYAN STIDHAM GRACE L. SU AKBAR K. WALJEE
Division of Gastroenterology and Hepatology Department of Internal Medicine University of Michigan Medical Center Ann Arbor VA Healthcare System Ann Arbor, Michigan
FECAL DNA TESTING FOR COLORECTAL NEOPLASIA IN IBD: COULD IT BE AS SIMPLE AS A STOOL STUDY? Kisiel JB, Yab TC, Nazer Hussain FT, et al. Stool DNA testing for the detection of colorectal neoplasia in patients with inflammatory bowel disease. Aliment Pharmacol Ther 2013;37:546–554. Patients with long-standing inflammatory bowel disease (IBD) in the colon are at increased risk for dysplasia and colorectal cancer (Cancer 1992;70[suppl 5]:1313–1316; Gastroenterology 1991;100[5 Pt 1]:1241). Owing to this increased risk, IBD patients typically undergo surveillance colonoscopy to detect colorectal neoplasia (CRN): Colorectal cancer, high-grade dysplasia (HGD), or low-grade dysplasia found in random biopsies of colonic mucosa. New techniques such as chromoendoscopy with targeted biopsies have shown to be an alternative to improve the yield of surveillance colonoscopy in these patients. Despite these advances, there remain limitations to current surveillance tools, which include undersampling and unknown ideal frequency of surveillance. Stool assay of exfoliated DNA markers for CRN may represent a noninvasive adjunctive tool for the detection of CRN in IBD patients. In non-IBD patients, the feasibility of detecting tumor-specific products in the stool has been demonstrated (Gastroenterology 2005;128:192–206; Cancer 2006;106:277–283). Prior tissuebased studies have shown that there are various molecular alterations, such as acquired mutations or abnormal methylations, associated with IBD-CRN. The primary aims of this study were to assess the discriminant value of 5 mutation markers (p53, APC, BRAF, K-ras, and PIK3CA) and 4 methylation markers (VIM, BMP3, EYA4, septin 9) based on DNA extracted from tissue specimens, and to assess the feasibility of stool DNA testing for detection of premalignant and malignant IBD-CRN. A single-center archive of IBD-CRC cases and IBD controls were used to identify tissue specimens. Cases and controls were matched for age, gender, disease duration, anatomic extent, and primary sclerosing cholangitis (PSC) status. DNA was then extracted from paraffin-embedded tissues and amplified using real-time polymerase chain reaction. The 25 case and 25 control patients in the tissue study were well-matched in terms of clinical characteristics including age, gender, duration and extent of disease, and PSC cases. DNA sequencing for the case samples revealed 14 mutation markers across 3 genes (APC, K-ras, and p53; no mutations were identified on BRAF or PIK3CA) with p53 found to be the most informative marker. The aggregate sensitivity of using all mutation markers was 60% with a specificity of 100%; there were no mutations
480
SELECTED SUMMARIES
found in control tissues. Receiver operating characteristic curves for each of the methylation markers demonstrated higher areas under the curve for methylated EYA4 (mEYA4), VIM (mVIM), and BMP3 (mBMP3). Given the results of the tissue study, case and control sets were analyzed for detection of CRN by stool assay of 3 methylated genes: BMP3, Vimentin, and EYA4. The fourth methylated gene assayed was NDGR4, which was selected because of high discrimination for sporadic CRN in studies performed after the tissue study. A total of 23 cases and 220 controls were found to be eligible. Of these, 19 case patients with biopsy-proven CRN and 35 control patients without CRN submitted stool. In a comparison of the case and control sets, case patients were significantly more likely to have extensive disease involvement and longer disease duration. There was no difference in disease activity between the 2 groups. Of the 19 cases with confirmed CRN, 9 patients had cancer with a medium size of 2.3 cm, 4 had HGD, and 6 had low-grade dysplasia. All 4 methylated genes showed high discrimination for cancer. Stool assay of mBMP3 alone was 100% sensitive for CRC, 84% for all CRN, and 91% specific. The combination of mBMP3 and mNDRG4 was 100% sensitive for both CRC and HGD with 89% specificity. In comparison of patients with ulcerative colitis (UC) and Crohn’s disease, Marker levels were not different between UC and Crohn’s disease (CD) patients. In multivariate analyses including age, gender, disease duration, disease extent, and presence of PSC, methylation markers for CRN detection remained significant. Comment. Over the past decade, there have been several sets of guidelines regarding colon cancer screening and surveillance in patients with UC (Gut 2002;51[suppl 5]:V10–V12; Gastroenterology 2003;124:544–560; Gastrointest Endosc 2006;63:546–557; Inflamm Bowel Dis 2005;11:314–321; Am J Gastroenterol 2010;105:501–524; Gut 2010;59:666–689). These recommendations all include the use of colonoscopy. Unfortunately, the prevalence of colonoscopy surveillance to detect CRN ranges from 25% to 64% (Gastroenterology 2010;139:1511–1518; Gastrointest Endosc 2007;65:432–439; World J Gastroenterol 2009;15:226–230). Recent studies investigating the low rate of surveillance have found that factors associated with higher compliance include the absence of significant comorbidity and more than 3 UC-related outpatient visits (Gastroenterology 2010;139:1511–1518). Other factors affecting low surveillance rate may include patient concerns regarding risks of colonoscopy and the inconvenience of bowel prep or fasting before the procedure. The availability of a noninvasive test may serve to increase compliance with colorectal cancer screening and surveillance in IBD patients. The most common noninvasive approach to screening in the general population has been the detection of occult blood, which lacks sensitivity and specificity, and is unreliable in IBD patients given the inflammatory nature of the disease. Many cancers or premalignant adenomas do not bleed and can be missed (JAMA
GASTROENTEROLOGY Vol. 145, No. 2
1990;263:76–78; JAMA 1993;269:1262–1267). The genetics of CRC provide the basis for analysis of fecal DNA (Science 1992;256:102–105; Clin Chim Acta 2002;315:157–168). Altered DNA from a CRN arises from the neoplasm itself as opposed to circulation and is released via exfoliation. Neoplasm-specific DNA alterations have been well characterized (Eur J Gastroenterol Hepatol 1992;5:205–213; Eur J Gastroenterol Hepatol 1993;5:219–225). From this, a stool assay system was developed to identify a spectrum of DNA alterations that are associated with CRN (Gastroenterology 2000;119:1219–1227). Several studies have demonstrated the feasibility of detecting tumor-specific products in the stool (Gastroenterology 2005;128:192–206; Cancer 2006;106:277–283). Stool analyzed in blinded fashion from patients with CRC, adenomas, or normal colon revealed even an early generation fecal DNA assay was 91% sensitive for cancer and 82% for adenomas >1 cm with a specificity of 91% (Gastroenterology 2000;119:1219–1227). A large, prospective, multicenter study in >4000 average-risk asymptomatic patients over the age of 50 showed that fecal DNA test had a significantly higher sensitivity compared with stool Hemoccult test (N Engl J Med 2004;351:2704–2714). The authors of this study have addressed an interesting and important question. Patients with UC are at increased risk for developing CRC; however, the rate of surveillance colonoscopies within this group is highly variable. Even with current surveillance techniques, colonoscopy is an imperfect practice. The authors found 2 of the 9 CRC cases with positive stool results were missed on colonoscopy and diagnosed only after colectomy. The use of fecal DNA testing could be integral to the care of IBD patients. The design of this study was a major strength. In the tissue study, cases and controls were well-matched and the authors were able to determine which methylation markers were highly discriminant for IBD-CRN as opposed to relying on and extrapolating from prior studies performed with sporadic, non-IBD cases. They were also able to confirm prior observations in IBD cases with regard to mBMP3 and mEYA4. Based on the results of the tissue study, the authors demonstrated that fecal DNA testing was capable of achieving high detection rates for both CRC and dysplasia. The authors were able to achieve the target sample size to address the primary endpoints. The power to analyze subgroups, however, was limited, and the authors acknowledge this. A particular area of interest would have been to determine any differences in stool DNA markers between flat, dysplastic lesions from other dysplastic lesions. The finding of flat HGD or carcinoma on endoscopic biopsies is an indication for colectomy. Although controversial, there is some evidence to suggest that flat, low-grade dysplasia is also an indication for colectomy because of the high rate of progression to HGD or cancer (Am J Gastroenterol 2002;97:922–927; Gastroenterology 2003;125:1311–1319; Gut 2003;52:1127–1132; Dis Colon Rectum 2002;45:615–620; Gastroenterology
August 2013
SELECTED SUMMARIES 481
2004; 127:950–956). The sensitivity for low-grade dysplasia in the fecal DNA assay used in this study was at best 67%. Furthermore, owing to limited power in the subgroup analyses, the lack of an effect upon marker levels by disease duration, severity and extent of disease, and presence of concomitant PSC could be falsely negative. Overall, fecal DNA testing seems to be a promising alternative to colonoscopy for screening and surveillance purposes. Stool assay may be useful for early detection of IBD-CRN, and could also help to guide the frequency of colonoscopy surveillance to tailor individual risk. Larger studies are needed, however, to confirm the results demonstrated in this study, as well as to provide the power for greater sensitivity in subgroup analyses. SUSAN Y. QUAN SHAMITA B. SHAH Stanford University School of Medicine Division of Gastroenterology and Hepatology Stanford, California
REGRESSION OF CIRRHOSIS WITH LONG–TERM TENOFOVIR TREATMENT Marcellin P, Gane E, Buti M, et al. Regression of cirrhosis during treatment with tenofovir disoproxil fumarate for chronic hepatitis B: a 5-year open-label follow-up study. Lancet 2013;381:468–475. Cirrhosis is the common final path of different chronic liver diseases. A couple of decades ago, cirrhosis was considered an irreversible state. Since the development of antiviral therapy for chronic hepatitis B and C, it has been observed that liver fibrosis, and to certain extent cirrhosis, can regress if the underlying etiology is under control. However, high-quality data to document this phenomenon are scarce. In a recent paper, Marcellin et al reported the results of long-term tenofovir disoproxil fumarate treatment in patients with chronic hepatitis B (Lancet 2013;381:468–475). Tenofovir is among the most potent antiviral agents against hepatitis B virus (HBV). In the original registration trial involving 266 patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B and 375 patients with HBeAg-negative chronic hepatitis B, tenofovir demonstrated superior antiviral efficacy to adefovir dipivoxil (N Engl J Med 2008;359:2442–2455). Among HBeAgpositive patients, 76% of those treated with tenofovir and 13% of those treated with adefovir had HBV DNA suppressed below 69 IU/mL at week 48 (P < .001). Corresponding figures in HBeAg-negative patients were 93% and 63%, respectively (P < .001). After week 48, patients in both groups continued tenofovir regardless of initial treatment assignment and were prospectively followed for 8 years. The current report by Marcellin et al was a planned analysis at 5 years (Lancet 2013;381:468–475). Although follow-up liver biopsy was optional, this study was remarkable in that 489 of the
original 641 randomized patients completed 5 years of follow-up, and 348 patients (54% of the original cohort) also agreed to repeat liver biopsy at 5 years. Therefore, this study provided valuable data on the histologic benefits of long-term antiviral therapy. The majority of patients had marked reduction in hepatic necroinflammation. The proportion with no or mild necroinflammation (Knodell score 3) increased from 8% at baseline to 80% at 5 years. Similarly, fibrosis also improved with time. No or mild fibrosis was found in 39% at baseline and 63% at 5 years. The proportion with pronounced bridging fibrosis or cirrhosis (Ishak stage 4–6) decreased from 38% to 12%. Altogether, 51% had improvement in fibrosis stage. Among 96 patients with cirrhosis at baseline, 71 (74%) had regression of cirrhosis, 70 of whom also showed improvement in Ishak fibrosis score by 2 points. Low body mass index (<25 kg/m2) was the only independent factor associated with regression of cirrhosis. In addition, 73% of HBeAg-positive and 85% of HBeAgnegative patients had normal alanine aminotransferase at 5 years. By intention-to-treat analysis, 65% of HBeAgpositive and 83% of HBeAg-negative patients had HBV DNA suppressed to <69 IU/mL. Of HBeAg-positive patients, 40% achieved HBeAg seroconversion. No drugresistant mutant was detected. Because of structural similarities between tenofovir and adefovir, nephrotoxicity and bone loss have been a concern. However, in this 5-year study, only 1 of 585 patients had creatinine clearance of <50 mL/min, and 7 (1%) patients had serum phosphorus of <0.65 mmol/L. Comment. Regression of fibrosis has been observed ever
since effective antiviral therapy became available. In a small study of 20 chronic hepatitis B patients treated with lamivudine for 1 year, 7 had improvement in fibrosis, 12 had static disease, and only 1 had progression from Knodell stage 0 to stage 1 disease (J Hepatol 1999;30:743–748). Subsequent studies largely supported the initial observation. In another study of 69 patients treated with entecavir, liver biopsy was repeated after a median of 6 years (range, 3–7; Hepatology 2010;52:886–893). Overall, 88% had improvement in fibrosis, and 58% had a reduction in Ishak fibrosis score by 2 points. All 10 patients with advanced fibrosis or cirrhosis at baseline had improvement in fibrosis stage. The current study by Marcellin et al adds further proof by including a large number of patients with repeated liver biopsies. In particular, the study included a sizable cohort of cirrhotic patients. Is this unequivocal evidence of cirrhosis regression? Although there is little doubt that fibrosis can improve with treatment, the reversibility of cirrhosis remains controversial. Cirrhosis involves not only deposition of fibrous tissue, but also changes in liver architecture. In addition, studies with serial liver biopsies are not foolproof. Because a typical liver biopsy specimen only represents 1/ 50,000 of the entire liver volume, sampling variability is common. If the less severe area is biopsied at the second
SELECTED SUMMARIES 479
can cause weight loss and may have anti-inflammatory effects. Furthermore only 1 measurement of BMI was analyzed when subjects were recruited, which may have been several years before diagnosis, and it is conceivable that BMI closer to diagnosis is more predictive of incident IBD. However, data from 1 cohort in the study suggested only a minimal weight gain of 1.5 kg from recruitment to a mean follow-up of 3.7 years. Although the authors of this study found no association between obesity and development of IBD, they note that only BMI was studied as a measure of obesity, which has a poor linear relationship with total body fat. Alternative measures of adiposity may have more prognostic value, such as waist-to-hip ratio, which is a more accurate marker of central obesity and visceral fat. Furthermore recent studies have suggested that mesenteric fat deposition rather than subcutaneous fat is a primary contributor to inflammation in CD (Gut 2012;61:78–85). Future studies using novel methods to evaluate fat stores, including visceral, subcutaneous, and mesenteric deposits, may help to determine whether obesity is a risk factor for the development of IBD. The developing field of analytic morphometrics, which uses measurements based on imaging to evaluate anatomic features that may predict medical outcomes, could provide answers. A recent study using analytic morphomics found that abdominal subcutaneous fat is an independent predictor of surgical site infections, and that subcutaneous fat improved model predictions of surgical site infections compared with BMI (J Am Coll Surg 2011;213:236–244). That same methodology, when applied to obesity and IBD, may provide more nuanced answers by evaluating specific fat storage deposits and their association with incident IBD. Obesity has been linked with the development of other inflammatory conditions, such as rheumatoid arthritis, which has risen in incidence and prevalence in recent years. Analysis of a cohort from Olmsted County, Minnesota, suggested that obesity accounted for 52% of the increased risk for developing rheumatoid arthritis between 1985 and 2007 (Arthritis Care Res 2013;65:71–77). Creeping fat, recognized for decades as a marker of CD activity, may be a source of disease-promoting adipokines, and is correlated with muscular hypertrophy, fibrosis, and stricturing (Inflamm Bowel Dis 2012;18:1550–1557). The cytokine milieu, which is a byproduct of fat stores, may be associated with development of CD and other inflammatory conditions, such as rheumatoid arthritis. In the end, this large, prospective, cohort study with extended follow-up found no association between incident IBD and obesity as measured by BMI. With the rising incidence of IBD and widespread adoption of Western dietary habits, examination of more nuanced measures of adiposity such as waist-to-hip ratio and mesenteric fat may provide further clarity (Gastroenterology 2013;144[suppl 1]:S-87). JOSHUA B. MAX RYAN STIDHAM GRACE L. SU AKBAR K. WALJEE
Division of Gastroenterology and Hepatology Department of Internal Medicine University of Michigan Medical Center Ann Arbor VA Healthcare System Ann Arbor, Michigan
FECAL DNA TESTING FOR COLORECTAL NEOPLASIA IN IBD: COULD IT BE AS SIMPLE AS A STOOL STUDY? Kisiel JB, Yab TC, Nazer Hussain FT, et al. Stool DNA testing for the detection of colorectal neoplasia in patients with inflammatory bowel disease. Aliment Pharmacol Ther 2013;37:546–554. Patients with long-standing inflammatory bowel disease (IBD) in the colon are at increased risk for dysplasia and colorectal cancer (Cancer 1992;70[suppl 5]:1313–1316; Gastroenterology 1991;100[5 Pt 1]:1241). Owing to this increased risk, IBD patients typically undergo surveillance colonoscopy to detect colorectal neoplasia (CRN): Colorectal cancer, high-grade dysplasia (HGD), or low-grade dysplasia found in random biopsies of colonic mucosa. New techniques such as chromoendoscopy with targeted biopsies have shown to be an alternative to improve the yield of surveillance colonoscopy in these patients. Despite these advances, there remain limitations to current surveillance tools, which include undersampling and unknown ideal frequency of surveillance. Stool assay of exfoliated DNA markers for CRN may represent a noninvasive adjunctive tool for the detection of CRN in IBD patients. In non-IBD patients, the feasibility of detecting tumor-specific products in the stool has been demonstrated (Gastroenterology 2005;128:192–206; Cancer 2006;106:277–283). Prior tissuebased studies have shown that there are various molecular alterations, such as acquired mutations or abnormal methylations, associated with IBD-CRN. The primary aims of this study were to assess the discriminant value of 5 mutation markers (p53, APC, BRAF, K-ras, and PIK3CA) and 4 methylation markers (VIM, BMP3, EYA4, septin 9) based on DNA extracted from tissue specimens, and to assess the feasibility of stool DNA testing for detection of premalignant and malignant IBD-CRN. A single-center archive of IBD-CRC cases and IBD controls were used to identify tissue specimens. Cases and controls were matched for age, gender, disease duration, anatomic extent, and primary sclerosing cholangitis (PSC) status. DNA was then extracted from paraffin-embedded tissues and amplified using real-time polymerase chain reaction. The 25 case and 25 control patients in the tissue study were well-matched in terms of clinical characteristics including age, gender, duration and extent of disease, and PSC cases. DNA sequencing for the case samples revealed 14 mutation markers across 3 genes (APC, K-ras, and p53; no mutations were identified on BRAF or PIK3CA) with p53 found to be the most informative marker. The aggregate sensitivity of using all mutation markers was 60% with a specificity of 100%; there were no mutations
480
SELECTED SUMMARIES
found in control tissues. Receiver operating characteristic curves for each of the methylation markers demonstrated higher areas under the curve for methylated EYA4 (mEYA4), VIM (mVIM), and BMP3 (mBMP3). Given the results of the tissue study, case and control sets were analyzed for detection of CRN by stool assay of 3 methylated genes: BMP3, Vimentin, and EYA4. The fourth methylated gene assayed was NDGR4, which was selected because of high discrimination for sporadic CRN in studies performed after the tissue study. A total of 23 cases and 220 controls were found to be eligible. Of these, 19 case patients with biopsy-proven CRN and 35 control patients without CRN submitted stool. In a comparison of the case and control sets, case patients were significantly more likely to have extensive disease involvement and longer disease duration. There was no difference in disease activity between the 2 groups. Of the 19 cases with confirmed CRN, 9 patients had cancer with a medium size of 2.3 cm, 4 had HGD, and 6 had low-grade dysplasia. All 4 methylated genes showed high discrimination for cancer. Stool assay of mBMP3 alone was 100% sensitive for CRC, 84% for all CRN, and 91% specific. The combination of mBMP3 and mNDRG4 was 100% sensitive for both CRC and HGD with 89% specificity. In comparison of patients with ulcerative colitis (UC) and Crohn’s disease, Marker levels were not different between UC and Crohn’s disease (CD) patients. In multivariate analyses including age, gender, disease duration, disease extent, and presence of PSC, methylation markers for CRN detection remained significant. Comment. Over the past decade, there have been several sets of guidelines regarding colon cancer screening and surveillance in patients with UC (Gut 2002;51[suppl 5]:V10–V12; Gastroenterology 2003;124:544–560; Gastrointest Endosc 2006;63:546–557; Inflamm Bowel Dis 2005;11:314–321; Am J Gastroenterol 2010;105:501–524; Gut 2010;59:666–689). These recommendations all include the use of colonoscopy. Unfortunately, the prevalence of colonoscopy surveillance to detect CRN ranges from 25% to 64% (Gastroenterology 2010;139:1511–1518; Gastrointest Endosc 2007;65:432–439; World J Gastroenterol 2009;15:226–230). Recent studies investigating the low rate of surveillance have found that factors associated with higher compliance include the absence of significant comorbidity and more than 3 UC-related outpatient visits (Gastroenterology 2010;139:1511–1518). Other factors affecting low surveillance rate may include patient concerns regarding risks of colonoscopy and the inconvenience of bowel prep or fasting before the procedure. The availability of a noninvasive test may serve to increase compliance with colorectal cancer screening and surveillance in IBD patients. The most common noninvasive approach to screening in the general population has been the detection of occult blood, which lacks sensitivity and specificity, and is unreliable in IBD patients given the inflammatory nature of the disease. Many cancers or premalignant adenomas do not bleed and can be missed (JAMA
GASTROENTEROLOGY Vol. 145, No. 2
1990;263:76–78; JAMA 1993;269:1262–1267). The genetics of CRC provide the basis for analysis of fecal DNA (Science 1992;256:102–105; Clin Chim Acta 2002;315:157–168). Altered DNA from a CRN arises from the neoplasm itself as opposed to circulation and is released via exfoliation. Neoplasm-specific DNA alterations have been well characterized (Eur J Gastroenterol Hepatol 1992;5:205–213; Eur J Gastroenterol Hepatol 1993;5:219–225). From this, a stool assay system was developed to identify a spectrum of DNA alterations that are associated with CRN (Gastroenterology 2000;119:1219–1227). Several studies have demonstrated the feasibility of detecting tumor-specific products in the stool (Gastroenterology 2005;128:192–206; Cancer 2006;106:277–283). Stool analyzed in blinded fashion from patients with CRC, adenomas, or normal colon revealed even an early generation fecal DNA assay was 91% sensitive for cancer and 82% for adenomas >1 cm with a specificity of 91% (Gastroenterology 2000;119:1219–1227). A large, prospective, multicenter study in >4000 average-risk asymptomatic patients over the age of 50 showed that fecal DNA test had a significantly higher sensitivity compared with stool Hemoccult test (N Engl J Med 2004;351:2704–2714). The authors of this study have addressed an interesting and important question. Patients with UC are at increased risk for developing CRC; however, the rate of surveillance colonoscopies within this group is highly variable. Even with current surveillance techniques, colonoscopy is an imperfect practice. The authors found 2 of the 9 CRC cases with positive stool results were missed on colonoscopy and diagnosed only after colectomy. The use of fecal DNA testing could be integral to the care of IBD patients. The design of this study was a major strength. In the tissue study, cases and controls were well-matched and the authors were able to determine which methylation markers were highly discriminant for IBD-CRN as opposed to relying on and extrapolating from prior studies performed with sporadic, non-IBD cases. They were also able to confirm prior observations in IBD cases with regard to mBMP3 and mEYA4. Based on the results of the tissue study, the authors demonstrated that fecal DNA testing was capable of achieving high detection rates for both CRC and dysplasia. The authors were able to achieve the target sample size to address the primary endpoints. The power to analyze subgroups, however, was limited, and the authors acknowledge this. A particular area of interest would have been to determine any differences in stool DNA markers between flat, dysplastic lesions from other dysplastic lesions. The finding of flat HGD or carcinoma on endoscopic biopsies is an indication for colectomy. Although controversial, there is some evidence to suggest that flat, low-grade dysplasia is also an indication for colectomy because of the high rate of progression to HGD or cancer (Am J Gastroenterol 2002;97:922–927; Gastroenterology 2003;125:1311–1319; Gut 2003;52:1127–1132; Dis Colon Rectum 2002;45:615–620; Gastroenterology
August 2013
SELECTED SUMMARIES 481
2004; 127:950–956). The sensitivity for low-grade dysplasia in the fecal DNA assay used in this study was at best 67%. Furthermore, owing to limited power in the subgroup analyses, the lack of an effect upon marker levels by disease duration, severity and extent of disease, and presence of concomitant PSC could be falsely negative. Overall, fecal DNA testing seems to be a promising alternative to colonoscopy for screening and surveillance purposes. Stool assay may be useful for early detection of IBD-CRN, and could also help to guide the frequency of colonoscopy surveillance to tailor individual risk. Larger studies are needed, however, to confirm the results demonstrated in this study, as well as to provide the power for greater sensitivity in subgroup analyses. SUSAN Y. QUAN SHAMITA B. SHAH Stanford University School of Medicine Division of Gastroenterology and Hepatology Stanford, California
REGRESSION OF CIRRHOSIS WITH LONG–TERM TENOFOVIR TREATMENT Marcellin P, Gane E, Buti M, et al. Regression of cirrhosis during treatment with tenofovir disoproxil fumarate for chronic hepatitis B: a 5-year open-label follow-up study. Lancet 2013;381:468–475. Cirrhosis is the common final path of different chronic liver diseases. A couple of decades ago, cirrhosis was considered an irreversible state. Since the development of antiviral therapy for chronic hepatitis B and C, it has been observed that liver fibrosis, and to certain extent cirrhosis, can regress if the underlying etiology is under control. However, high-quality data to document this phenomenon are scarce. In a recent paper, Marcellin et al reported the results of long-term tenofovir disoproxil fumarate treatment in patients with chronic hepatitis B (Lancet 2013;381:468–475). Tenofovir is among the most potent antiviral agents against hepatitis B virus (HBV). In the original registration trial involving 266 patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B and 375 patients with HBeAg-negative chronic hepatitis B, tenofovir demonstrated superior antiviral efficacy to adefovir dipivoxil (N Engl J Med 2008;359:2442–2455). Among HBeAgpositive patients, 76% of those treated with tenofovir and 13% of those treated with adefovir had HBV DNA suppressed below 69 IU/mL at week 48 (P < .001). Corresponding figures in HBeAg-negative patients were 93% and 63%, respectively (P < .001). After week 48, patients in both groups continued tenofovir regardless of initial treatment assignment and were prospectively followed for 8 years. The current report by Marcellin et al was a planned analysis at 5 years (Lancet 2013;381:468–475). Although follow-up liver biopsy was optional, this study was remarkable in that 489 of the
original 641 randomized patients completed 5 years of follow-up, and 348 patients (54% of the original cohort) also agreed to repeat liver biopsy at 5 years. Therefore, this study provided valuable data on the histologic benefits of long-term antiviral therapy. The majority of patients had marked reduction in hepatic necroinflammation. The proportion with no or mild necroinflammation (Knodell score 3) increased from 8% at baseline to 80% at 5 years. Similarly, fibrosis also improved with time. No or mild fibrosis was found in 39% at baseline and 63% at 5 years. The proportion with pronounced bridging fibrosis or cirrhosis (Ishak stage 4–6) decreased from 38% to 12%. Altogether, 51% had improvement in fibrosis stage. Among 96 patients with cirrhosis at baseline, 71 (74%) had regression of cirrhosis, 70 of whom also showed improvement in Ishak fibrosis score by 2 points. Low body mass index (<25 kg/m2) was the only independent factor associated with regression of cirrhosis. In addition, 73% of HBeAg-positive and 85% of HBeAgnegative patients had normal alanine aminotransferase at 5 years. By intention-to-treat analysis, 65% of HBeAgpositive and 83% of HBeAg-negative patients had HBV DNA suppressed to <69 IU/mL. Of HBeAg-positive patients, 40% achieved HBeAg seroconversion. No drugresistant mutant was detected. Because of structural similarities between tenofovir and adefovir, nephrotoxicity and bone loss have been a concern. However, in this 5-year study, only 1 of 585 patients had creatinine clearance of <50 mL/min, and 7 (1%) patients had serum phosphorus of <0.65 mmol/L. Comment. Regression of fibrosis has been observed ever
since effective antiviral therapy became available. In a small study of 20 chronic hepatitis B patients treated with lamivudine for 1 year, 7 had improvement in fibrosis, 12 had static disease, and only 1 had progression from Knodell stage 0 to stage 1 disease (J Hepatol 1999;30:743–748). Subsequent studies largely supported the initial observation. In another study of 69 patients treated with entecavir, liver biopsy was repeated after a median of 6 years (range, 3–7; Hepatology 2010;52:886–893). Overall, 88% had improvement in fibrosis, and 58% had a reduction in Ishak fibrosis score by 2 points. All 10 patients with advanced fibrosis or cirrhosis at baseline had improvement in fibrosis stage. The current study by Marcellin et al adds further proof by including a large number of patients with repeated liver biopsies. In particular, the study included a sizable cohort of cirrhotic patients. Is this unequivocal evidence of cirrhosis regression? Although there is little doubt that fibrosis can improve with treatment, the reversibility of cirrhosis remains controversial. Cirrhosis involves not only deposition of fibrous tissue, but also changes in liver architecture. In addition, studies with serial liver biopsies are not foolproof. Because a typical liver biopsy specimen only represents 1/ 50,000 of the entire liver volume, sampling variability is common. If the less severe area is biopsied at the second