Checkpoint inhibitor hepatotoxicity: pathogenesis and management.

Immunotherapy, including immune checkpoint inhibitor (ICI) therapy, has been a paradigm shift in cancer therapeutics, producing durable cancer responses across a range of primary malignancies. ICI drugs increase immune activity against tumor cells, but may also reduce immune tolerance to self-antigens, resulting in immune-mediated tissue damage. ICI-associated hepatotoxicity usually manifests as hepatocellular enzyme elevation and may occur in 2%-25% of ICI-treated patients. Although ICI-associated hepatotoxicity is clinically and pathologically distinct from idiopathic autoimmune hepatitis, our understanding of its pathogenesis continues to evolve. Pending greater understanding of the pathophysiology, mainstay of management remains through treatment with high-dose corticosteroids. This approach works for many patients, but up to 30% of patients with high-grade hepatotoxicity may not respond to corticosteroids alone. Furthermore, atypical cholestatic presentations are increasingly recognized, and rare cases of fulminant hepatitis due to ICI hepatotoxicity have been reported. Optimal management for these challenging patients remains uncertain. Herein, we review the current understanding of pathogenesis of ICI-associated toxicities, with a focus on hepatotoxicity. Based on the existing literature, we propose evolving management approaches to incorporate strategies to limit excess corticosteroid exposure, and address rare but important presentations of cholestatic hepatitis and fulminant liver failure. Finally, as ICI hepatotoxicity frequently occurs in the context of treatment for advanced malignancy, we review the impact of hepatotoxicity and its treatment on cancer outcomes, and the overall safety of re-challenge with ICI, for patients who may have limited treatment options.

Evaluation of liver enzyme elevations and hepatotoxicity in patients treated with checkpoint inhibitor immunotherapy.

BACKGROUND AND AIMS: Immune checkpoint inhibitors (ICI) are increasingly used in cancer therapy. Elevated liver enzymes frequently occur in patients treated with ICI but evaluation is poorly described. We sought to better understand causes of liver enzyme elevation, investigation and management. METHODS: Patients treated with anti-PD-1, PDL-1 or CTLA-4 therapy in Phase I/II clinical trials between August 2012 and December 2018 were included. Clinical records of patients with significant liver enzyme elevations were retrospectively reviewed. RESULTS: Of 470 ICI-treated patients, liver enzyme elevation occurred in 102 (21.6%), attributed to disease progression (56; 54.9%), other drugs/toxins (7; 6.9%), other causes (22; 21.6%) and ICI immunotoxicity (17; 16.7%; 3.6% of total cohort). Immunotoxicity was associated with higher peak ALT than other causes of enzyme elevation (N = 17; M = 217, 95% CI 145-324 for immunotoxicity, N = 103; M = 74, 95% CI 59-92 for other causes; ratio of means 0.34, 95% CI 0.19-0.60, p = <0.001) and higher ALT:AST ratio (M = 1.27, 95% CI 0.78-2.06 for immunotoxicity, M = 0.69, 95% CI 0.59-0.80 for other causes, ratio of means 0.54, 95% CI 0.36-0.82, p = 0.004). Immunotoxicity was more often seen in patients with prior CPI exposure (41.2% of immunotoxicity vs 15.9% of patients without, p = 0.01), anti-CTLA-4 -containing ICI treatments (29.4% of immunotoxicity vs 6.8% of patients without, p = <0.001) and other organ immunotoxicity (76.5% of immunotoxicity vs 19.2% of patients without, p = <0.001). Cause for enzyme elevation was established in most patients after non-invasive investigation. Liver biopsy was reserved for four patients with atypical treatment response. CONCLUSIONS: Liver enzyme elevation is common in patients receiving ICI, but often has a cause other than immunotoxicity. A biochemical signature with higher ALT and ALT/AST ratio, a history of prior ICI exposure and other organ immunotoxicities may help to identify patients at a higher likelihood of immunotoxicity. Liver biopsy can be safely deferred in most patients. We propose an approach to diagnostic evaluation in patients with liver enzyme elevations following ICI exposure.

Risk of gallbladder cancer in patients with primary sclerosing cholangitis and radiographically detected gallbladder polyps.

BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) is associated with an increased risk of gallbladder cancer (GBC). Gallbladder polyps potentially harbour malignancy and thus international guidelines recommend prophylactic cholecystectomy for gallbladder polyps of any size in patients with PSC. To best inform patient care we sought to quantify the malignant risk of gallbladder polyps in patients with PSC. METHODS: A retrospective cohort study of patients followed in secondary and tertiary care settings in two large PSC clinics in North America was performed. RESULTS: In total, 453 patients were included with a median (IQR) follow-up time of 7.7 (4.1-12) years. A gallbladder polyp was radiographically detected in 16% (n = 71) with median size (range) of 4 (2-18) mm. In this group, post-cholecystectomy histology (n = 17) reported benign or no polyp in 77% (n = 13), dysplasia in 5.9% (n = 1) and malignancy in 18% (n = 3). The GBC rate was 8.8 (95% CI 1.8-25.7) per 1000 person-years in patients with a radiographically detected gallbladder polyp. GBC was associated with polyps >10 mm, interval growth or mass-like lesions on pre-operative imaging. In patients who did not have cholecystectomy (n = 50), the polyp was only transiently seen in 80% (n = 40), remained stable or decreased in size in 10% (n = 5) and increased in size in 6% (n = 3). The majority of gallbladder polyps did not show significant growth over time (0.041 mm/year [95% CI -0.017 to 0.249]). CONCLUSIONS: Most gallbladder polyps in patients with PSC are benign. Short-term surveillance imaging may be considered prior to recommending immediate cholecystectomy in patients with PSC without high-risk imaging features.

Amino Acid Substitutions in Genotype 3a Hepatitis C Virus Polymerase Protein Affect Responses to Sofosbuvir.

BACKGROUND & AIMS: Sofosbuvir is a frequently used pan-genotype inhibitor of hepatitis C virus (HCV) polymerase. This drug eliminates most chronic HCV infections, and resistance-associated substitutions in the polymerase are rare. However, HCV genotype 3 responds slightly less well to sofosbuvir-based therapies than other genotypes. We collected data from England's National Health Service Early Access Program to search for virus factors associated with sofosbuvir treatment failure. METHODS: We collected patient serum samples and used the capture-fusion assay to assess viral sensitivity to sofosbuvir in 14 HCV genotype 3 samples. We identified polymorphisms associated with reduced response and created modified forms of HCV and replicons containing the substitutions of interest and tested their sensitivity to sofosbuvir and ribavirin. We examined the effects of these polymorphisms by performing logistic regression multivariate analysis on their association with sustained virologic response in a separate cohort of 411 patients with chronic HCV genotype 3 infection who had been treated with sofosbuvir and ribavirin, with or without pegylated interferon. RESULTS: We identified a substitution in the HCV genotype 3a NS5b polymerase at amino acid 150 (alanine [A] to valine [V]), V at position 150 was observed in 42% of patients) with a reduced response to sofosbuvir in virus replication assays. In patients treated with sofosbuvir-containing regimens, the A150V variant was associated with a reduced response to treatment with sofosbuvir and ribavirin, with or without pegylated interferon. In 326 patients with V at position 150, 71% achieved an sustained virologic response compared to 88% with A at position 150. In cells, V at position 150 reduced the response to sofosbuvir 7-fold. We found that another rare substitution, glutamic acid (E) at position 206, significantly reduced the response to sofosbuvir (8.34-fold reduction); the combinations of V at position 150 and E at position 206 reduced the virus response to sofosbuvir 35.77-fold. Additionally, in a single patient, we identified 5 rare polymorphisms that reduced sensitivity to sofosbuvir our cell system. CONCLUSIONS: A common polymorphism, V at position 150 in the HCV genotype 3a NS5b polymerase, combined with other variants, reduces the virus response to sofosbuvir. Clinically, infection with HCV genotype 3 containing this variant reduces odds of sustained virologic response. In addition, we identified rare combinations of variants in HCV genotype 3 that reduce response to sofosbuvir.

Noninvasive Predictors of High-Risk Varices in Patients with Non-Cirrhotic Portal Hypertension.

Non-cirrhotic portal hypertension (NCPH) comprises a heterogeneous group of liver disorders causing portal hypertension without cirrhosis and carries a high risk of variceal bleeding. Recent guidelines, based largely on patients with viral cirrhosis, suggest low likelihood of high risk varices (HRV) in patients with a liver stiffness measurement (LSM) <20 kPa and platelet count >150 × 109/L. In NCPH, LSM is often higher than healthy controls but lower than matched cirrhotic patients. The aim of this study was to assess whether LSM or other noninvasive assessments of portal hypertension could predict HRV in NCPH patients. Methods. Records of patients with NCPH seen at a single centre between 2007 and 2018 were reviewed retrospectively. Primary outcome measure was presence or absence of HRV at gastroscopy within 12 months of clinical assessment. Association of LSM or other clinical features of portal hypertension (spleen size, platelet count, platelet count/spleen length ratio (PSL), LSM-spleen length/platelet count ratio score (LSP)) with HRV and ability of these variables to predict HRV was analysed. Results. Of 44 patients with NCPH who met inclusion criteria, 34% (15/44) had HRV. In a multivariate model, spleen size and PSL correlated with HRV but platelet count, LSM, and LSP did not (spleen size: ß = 0.35, p = 0.02; OR 1.42, 95% CI 1.06-1.92; PSL: ß = -1.47, p = 0.02; OR 0.23, 95% CI 0.07-0.80). There was no significant difference between spleen size and PSL in predicting HRV (AUROC 0.81 (95% CI 0.66 - 0.91) versus 0.71 (95% CI 0.54 - 0.84), respectively, p = 0.400). Spleen size >17.2cm had sensitivity 78.6% and specificity 64.3% for prediction of HRV. Conclusions. In NCPH patients, spleen size may predict risk of HRV at gastroscopy within 12 months. LSM and platelet count are not useful to assess risk of HRV in NCPH.

SB 9200, a novel agonist of innate immunity, shows potent antiviral activity against resistant HCV variants.

SB 9200 is a novel, first-in-class oral modulator of innate immunity that is believed to act via the activation of the RIG-I and NOD2 pathways. SB 9200 has broad-spectrum antiviral activity against RNA viruses including hepatitis C virus (HCV), norovirus, respiratory syncytial virus, and influenza and has demonstrated activity against hepatitis B virus (HBV) in vitro and in vivo. In phase I clinical trials in chronically infected HCV patients, SB 9200 has been shown to reduce HCV RNA by up to 1.9 log10 . Here, we demonstrate the antiviral activity of SB 9200 against a HCV replicon system and patient derived virus. Using the HCV capture-fusion assay, we show that SB 9200 is active against diverse HCV genotypes and is also effective against HCV derived from patients who relapse following direct-acting antiviral treatment, including viruses containing known NS5A resistance-associated sequences. These data confirm the broad antiviral activity of SB 9200 and indicate that it may have clinical utility in HCV patients who have failed to respond to current antiviral regimens.

Development and validation of a "capture-fusion" model to study drug sensitivity of patient-derived hepatitis C.

UNLABELLED: Emerging therapies for chronic hepatitis C viral (HCV) infection involve inhibition of viral enzymes with drug combinations. Natural, or treatment-induced, enzyme polymorphisms reduce efficacy. We developed a phenotyping assay to aid drug selection based on viral transfer from monocytes to hepatocytes. We studied HCV in monocytes from infected patients and developed a model in which patient-derived HCV is "captured" by the cell line THP-1 and replication assessed after fusion to hepatoma cells. We found that monocytes from HCV-infected patients harbor virus that replicates when cells are fused to hepatocytes. THP-1 cells incubated with infected sera capture HCV, which replicates when fused to hepatocytes. Inhibitable replication of all HCV genotypes was achieved (42 of 52 isolates). We measured sensitivity of telaprevir (TVR) and alisporivir (AVR) in different genotypes, and showed differences in 50% inhibitory concentration (IC50 ) correlating with clinical response (TVR IC50 for genotype (G)1 was 0.042 ± 0.003 vs. 0.117 ± 0.015 µM for G3, whereas AVR IC50 for G1 was 0.139 ± 0.013 vs. 0.044 ± 0.007 µM for G3). We tested TVR-resistant viral isolates and identified changes in IC50 . One patient with a poor clinical response to TVR and wild-type viral sequence showed reduced TVR sensitivity in our assay. We studied samples from a 2-week TVR monotherapy study in which 5 of 8 patients with G3 HCV did not respond whereas 3 of 8 patients did. The "capture-fusion" assay correctly identified responders. CONCLUSION: The capture-fusion model represents a promising new technique that may help identify appropriate treatment strategies for patients with chronic HCV infection.

Second generation direct antivirals and the way to interferon-free regimens in chronic HCV.

Treatment for those infected with chronic hepatitis C virus [HCV] has until recently been hampered by the lack of therapies other than pegylated interferon and ribavirin, which have limited efficacy and a difficult side effect profile. To address this, multiple new direct acting antiviral drugs which specifically target the non-structural proteins involved in HCV replication are in phase II/III development. This review will discuss the HCV replication cycle, mechanisms of action of the new direct acting antiviral drugs, results from published trials into their efficacy and the potential for interferon free treatment regimens in the future.

Efficacy and safety of telaprevir in patients with genotype 1 hepatitis C infection.

Chronic hepatitis C infection represents a significant and growing health problem worldwide. Patients with genotype 1 hepatitis C respond poorly to the current standard of care, pegylated interferon and ribavirin, which is frequently associated with unpleasant side effects. Consequently new agents with improved efficacy and tolerability are needed. The efficacy and safety of the direct-acting antiviral agent telaprevir in the treatment of genotype 1 hepatitis C infection have been demonstrated in a number of clinical trials. The addition of telaprevir to standard therapy considerably improves response rates and allows response-guided shortening of treatment duration in a substantial number of treatment-naïve patients. Side effects associated with telaprevir therapy include rash, anaemia, gastrointestinal disturbance and anorectal discomfort. Telaprevir-resistant variants have been identified in patients who have failed telaprevir-containing therapy, and whether selection of these variants will compromise future therapeutic options is currently unknown. The efficacy and safety of telaprevir in the treatment of the most challenging patients, including those with recurrent hepatitis C following liver transplantation and those co-infected with HIV, remains to be established.

Endothelin-1 as a mediator and potential biomarker for interferon induced pulmonary toxicity.

Endothelin-1 is a potent vasoconstrictor and a therapeutic target in pulmonary arterial hypertension. Endothelial cells are the physiological source of endothelin-1 but in vitro data from our group shows that interferons (IFNα, IFNß or IFNγ) induce endothelin-1 in pulmonary vascular smooth muscle cells. IFNs are integral to innate immunity and their antiviral and immunomodulatory capability has been harnessed therapeutically; for example, IFNα plays a critical role in the treatment of chronic hepatitis C infection. However, in some patients, IFN causes pneumonitis and possibly irreversible pulmonary arterial hypertension. In this study, we found that of 16 patients undergoing a six-month course of IFNα therapy, two demonstrated considerably increased serum levels of endothelin-1. We propose that IFN therapy results in elevated levels of endothelin-1 in some patients and when clinically significant levels are reached, pulmonary side effects could ensue. This hypothesis can be easily tested in IFN-treated patients by measuring serum endothelin-1 levels and cardiopulmonary physiological parameters.

The emerging role of screen based simulators in the training and assessment of colonoscopists.

Incorporation of screen based simulators into medical training has recently gained momentum, as advances in technology have coincided with a government led drive to increase the use of medical simulation training to improve patient safety with progressive reductions in working hours available for junior doctors to train. High fidelity screen based simulators hold great appeal for endoscopy training. Potentially, their incorporation into endoscopy training curricula could enhance speed of acquisition of skills and improve patient comfort and safety during the initial phase of learning. They could also be used to demonstrate competence as part of the future relicensing and revalidation of trained endoscopists. Two screen based simulators are widely available for lower gastrointestinal endoscopy training, with a third recently produced in prototype. The utility of these simulators in lower gastrointestinal endoscopy training has been investigated, and construct and expert validity has been shown. Novices demonstrate a learning curve with simulator training that appears to represent real learning of colonoscopy skills. This learning transfers well to the real patient environment, with improvements in performance and patient discomfort scores in subsequent initial live colonoscopy. The significant limitations of currently available screen based simulators include cost implications, and restrictions on a role in certification and revalidation. Many questions remain to be answered by future research, including how best to incorporate screen based simulators into a colonoscopy training programme, their role in training in therapeutic endoscopy and the impact of simulator training on patient safety.

Effects of endothelin on submandibular salivary responses to parasympathetic stimulation in anaesthetized sheep.

Submandibular responses to stimulation of the parasympathetic chorda tympani nerve have been investigated in anaesthetized sheep before, during and after an intracarotid infusion of endothelin, which reduced the blood flow through the gland by 56+/-5%. Stimulation of the peripheral end of the chorda tympani nerve produced a frequency-dependent increase in the flow of submandibular saliva, and in sodium, potassium and protein output. The reduction in submandibular blood flow, which occurred in response to endothelin, was associated with a decrease in the flow of saliva at all frequencies tested amounting on average to 44+/-6% (P<0.01). The flow of saliva was linearly related to the blood flow before and after endothelin. Both parameters were also linearly related during the infusion of endothelin and the regression lines were parallel. Salivary sodium concentration was significantly increased at the lower frequencies (1 and 2 Hz). Protein output was generally reduced but the difference only achieved statistical significance during stimulation at 1 Hz (P<0.01). Thus, submandibular secretory responses to parasympathetic stimulation are significantly attenuated by reducing the blood flow through the gland in this way.