More Data, More Nuance with MMP-7: Best Biliary Atresia Biomarker

As noted by my previous blog (New Way to Diagnose Biliary Atresia), I am enthusiastic about the development of MMP-7 (Serum Matrix Metalloproteinase-7) as a biomarker for biliary atresia.

A new study (Wu J-F , Jeng Y-M, Chen H-L, Ni Y-H, Hsu H-Y, Chang M-H. Quantification of serum matrix metallopeptide 7 levels may assist the diagnosis and outcome prediction for biliary atresia. J Pediatr. 2019;208:30–7) and associated editorial provide additional data and nuance.

Key points:

  • “Wu et … studied 100 cholestatic infants presenting consecutively to their institution over a 10-year period, including 36 eventually diagnosed with biliary atresia. Median serum MMP-7 levels were significantly higher in biliary atresia at the time of diagnosis, with an optimal serum MMP-7 level of >1.43 ng/mL for predicting biliary atresia.  In comparison, similarly high MMP-7 levels were found in only 1 infant who was cholestatic without biliary atresia.”
  • “The authors found that serum MMP-7 levels were significantly lower in the 14 infants ≤30 days old diagnosed with biliary atresia, compared with the 22 infants >30 days old at diagnosis. In some cases, serum MMP-7 levels in younger infants with biliary atresia overlapped with those from infants with other liver diseases, such as neonatal hepatitis.”
  • After Kasai portoenterostomy: “Serum MMP-7 levels were significantly higher 6 months post-Kasai portoenterostomy in infants who later required liver transplant, with a serum MMP-7 level of >10.30 mg/dL optimally predicting transplant 3-4 years after Kasai portoenterostomy … serum MMP-7 levels are still high even in patients who do not need liver transplant.”
  • The authors “highlight 1 complication with using serum MMP-7 levels: values can vary widely among different enzyme-linked immunosorbent assay kits used.”

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New Way to Diagnose Biliary Atresia

Case report: Recently, our group consulted on a 3 week old infant (ex34 week) who weighed 2.8 kg and had cholestasis. In addition, he had a GGT in the 400s and an ultrasound notable for a “small” gallbladder.  Due to the patient’s small size, he underwent a HIDA (no excretion).   The GGT was actually improving but the clinical situation was concerning for biliary atresia.

Instead of arranging a liver biopsy, we were able to perform a MMP-7 (Serum Matrix Metalloproteinase-7) assay which will be commercially available soon.  The result, which returned in 48 hours, indicated that the child had a >95% likelihood of biliary atresia. Subsequently, this infant is recovering from a hepatoportoenterostomy. No liver biopsy was needed prior to surgery.

My take: The MMP-7 assay is a remarkable test which is going to rapidly change the approach to infants with cholestasis.  I expect that this test will be ordered along with a serum alpha-one antitrypsin phenotype and an ultrasound.  In those with persistent cholestasis with negative initial testing, it is likely that, in the majority, a genetic cholestasis panel would be pursued rather than a liver biopsy.

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Biliary Atresia and Bile Lakes

A retrospective study (DA Ginström et al. JPGN 2019; 488-94) review cholangitis associated with biliary atresia and the role of bile leaks.  This study encompasses a ~30 year period (1987-2016) and 61 patients.

Key findings: 

  • 54% had survived with their native liver at a median of 7.3 years; 28 (46%) had ≥ 1 cholangitis episodes/year
  • Cholangitis bouts were >5 times higher among patients with bile lakes
  • Management of bile lakes after 1995 (n=6) was with operative intestinal drainage (bile-lake jejunostomy) which resulted in disappearance or regression of bile lakes in all patients.  Associated with this, yearly cholangitis bouts decreased from 8.8 (4.2-14) to 1.1 (0.2-3.2). Prior to 1995, two patients were managed with PTCD; both died within one year.
  • Among patients who had surgical drainage of their bile lakes, 4 have survived jaundice-free and 2 received liver transplants at 1.3 and 4.9 years after intestinal drainage.

My take: This report provides insight into the management of bile lakes (also referred to as intrahepatic biliary cysts) indicating that bile-lake jejunostomy is effective in symptomatic patients.

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Blood Test is Better Than a Liver Biopsy for Biliary Atresia

A recent study (L Yang et al. Hepatology 2018; 68: 2069-72) confirms the utility of Serum Matrix Metalloproteinase-7 (MMP-7) as a biomarker for biliary atresia (BA). The authors studied MMP-7 among healthy controls (n=72 with 54 <6 months) and among 135 with cholestasis (75 with BA, 60 with non-BA).  BA samples were taken at a median age of 54 days.

Key findings:

  • Median concentration for MMP-7 was 2.86 ng/mL in healthy controls, 11.47 ng/mL for non-BA cholestasis, and 121.1 ng/mL for BA.
  • Using a cutoff value of 52.85 ng/mL, the diagnostic sensitivity and specificity were 98.67% and 95.0% respectively.
  • The AUC for MMP-7 in BA was 0.99 compared for AUC for GGT of 0.72.  The sensitivity and specificity for GGT was much lower at 64% and 72% respectively with a cutoff of 314 U/L.
  • The predictive value for MMP-7 was particularly impressive, 74 of 75 BA  subjects were correctly identified as having BA.  Only 3 non-BA patients were incorrectly assigned a BA diagnosis based on MMP-7 values.
  • The authors noted that MMP-7 testing indicates that there are no substantial changes in its values for normal subjects extending to 54 years of age.
  • One limitation the authors note is the relatively small number of patients with non-BA syndromatic intrahepatic cholestasis which made up less than 30% of their non-BA cohort.  Thus, more testing in specific populations is needed.

My take: The diagnostic performance of MMP-7** appears to be superior to that of a liver biopsy (though this was not directly compared in this study) in predicting BA and could obviate the need for most liver biopsies in infants with cholestasis.  Those with high MMP-7 values would proceed directly to intraoperative cholangiogram with possible hepatoportojejunostomy. Those with non-BA MMP-7 values and persistent cholestasis could undergo additional investigation with genetic panels and/or other metabolic/infectious testing.

**This assay is likely to be commercially-available in the coming weeks according to a colleague at Cincnnati Children’s Hospital.  The expectation is an approximagely 2-day turnaround.

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Bilary Atresia Prognosis After 2-Year Survival with Native Liver

A recent study (M Witt et al. JPGN 2018; 689-94) indicates that among patients with biliary atresia who reached 2 years of life with native liver survival (NLS), they continued to be at risk for progressive liver failure.

Key findings:

  • Upon a median follow-up of 16.4 years, NLS rates at 5, 10, 15, 18 years of age were 89%, 72%, 60%, 54%, respectively.
  • Corresponding overall survival rates were 98%, 90%, 87%, 87%, respectively
  • NLS ended in 37% by liver transplantation (LTx) and in 6% by (pre-transplant) mortality.
  • Abstract Link: Prognosis of Biliary Atresia After 2-year Survival With Native Liver

My take: This data provides more precise information for families about prognosis and reinforces the need for careful followup.

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Liver Shorts November 2018

J Ge et al. Hepatology 2018; 68: 1101-10.  This study reviewed liver donation offers between 2010 to 2014.  This study found that 5.6% of men (293/5202) and 6.2% of women (179/2899) received a pediatric donor as a first offer.  Women, but not men, who received a pediatric first offer had a lower risk of waitlist mortality than with those who received adult organ offers. The authors recommend that “offers of pediatric donor liver be prioritized to women, who are generally shorter stature, once alllocation to the entire…pediatric waitlist pool has occurred.”

CA Chapin et al. Hepatology 2018; 68: 1087-1100.  This study found that patients with indeterminate pediatric acute liver failure (iPALF) have a unique pattern of dense CD8+ T-cell infiltrate that is also perforin-positive adn CD103-positive.  These CD8+ cells are a biomarker for immune dysregulation. These CD8+ dense pattern was found in the 27 of 33 patients with iPALF; 3 had moderate and 3 had minimal staining pattern (per table 2).  The dense CD8+ pattern was seen in 3 of 9 with autoimmune hepatitis and in 1 of 14 with other liver diseases.

E-D Pfister et al. Liver Transplantation 2018; 24: 1186-98.  This study examined patient (n=338) and graft survival in the pediatric population (median age 14.0 years) with Wilson’s disease (1968-2013).  Overall, patient survival was 87% at 1 year, 84% at 5 years, and 81% at 10 years.  Though, the survival was much improved since 2009.

JA Bezzerra et al. Hepatology 2018; 68: 1163-73. This review summarized a research workshop (June 2017) focused on the clinical and research challenges for biliary atresia.

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How Often Is Surgical Treatment for Biliary Atresia Delayed Beyond 60 Days?

It is recognized that there is often a delay in the diagnosis of biliary atresia (BA).  A recent study (MR Townsend et al. J Pediatr 2018; 199: 237-42) indicates that hepatoportoenterostomy (HPE) or Kasai procedure is performed in only 37.7% of patients with BA prior to 60 days of age. The data was obtained from the Agency for Healthcare Research and Quality’s Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample files from 2000-2011.

  • Risk factors for delayed HPE: This study of 1243 patients with BA found that those with delayed HPE were more often uninsured–all self-pay patients had HPE after 60 days, more often black (aOR 4.22), and less likely at a teaching hospital (aOR 0.27).
  • Delayed HPE was associated with increased adverse perioperative outcomes and increased cost.

My take: We have a long way to go if we are going to consistently identify and treat BA in a timely manner.

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