Marcus Schuchmann

Targeted Disruption of the Mouse Caspase 8 Gene Ablates Cell Death Induction by the TNF Receptors, Fas/Apo1, and DR3 and Is Lethal Prenatally

Homozygous targeted disruption of the mouse Caspase 8 (Casp8) gene was found to be lethal in utero. The Caspase 8 null embryos exhibited impaired heart muscle development and congested accumulation of erythrocytes. Recovery of hematopoietic colony-forming cells from the embryos was very low. In fibroblast strains derived from these embryos, the TNF receptors, Fas/Apo1, and DR3 were able to activate the Jun N-terminal kinase and to trigger IkappaB alpha phosphorylation and degradation. They failed, however, to induce cell death, while doing so effectively in wild-type fibroblasts. These findings indicate that Caspase 8 plays a necessary and nonredundant role in death induction by several receptors of the TNF/NGF family and serves a vital role in embryonal development.

Response to transarterial chemoembolization as a biological selection criterion for liver transplantation in hepatocellular carcinoma

Criteria to select patients with hepatocellular carcinoma (HCC) for liver transplantation (LT) are based on tumor size and number of nodules rather than on tumor biology. The present study was undertaken to assess the role of transarterial chemoembolization (TACE) in selecting patients with tumors suitable for LT. Ninety‐six consecutive patients with HCC were treated by repeatedly performed TACE, 62 of them exceeding the Milan criteria. Patients meeting the Milan criteria were immediately listed, and patients beyond the listing criteria were listed upon downstaging of the tumor following successful TACE. Fifty patients were finally transplanted. Of these 50 patients, 34 exceeded the Milan criteria. In these 96 patients, overall 5‐year survival was 51.9%. However, it was 80.9% for patients undergoing LT and 0% for patients without transplantation (P < 0.0001). Tumor recurrence was primarily influenced by the control of the disease through continued TACE during the waiting time. Freedom from recurrence after 5 years was 94.5% in patients (n = 39) with progress‐free TACE during the waiting time. Tumor recurrence was significantly higher in patients (n = 11) who after initial response to TACE progressed again before LT (freedom from recurrence 35.4%; P = 0.0017). Progress‐free course of TACE during the waiting time (P = 0.006; risk ratio, 8.95), and a limited number of tumor nodules as assessed in the surgical specimen (P = 0.025; risk ratio, 0.116) proved to be significant predictors for freedom from recurrence in the multivariate analysis. Milan criteria were without impact on recurrence. Our data suggest that sustained response to TACE is a better selection criterion for LT than the initial assessment of tumor size or number. Liver Transpl 12:1260‐1267, 2006.

Faldaprevir and Deleobuvir for HCV Genotype 1 Infection

BACKGROUND Interferon-free regimens would be a major advance in the treatment of patients with chronic hepatitis C virus (HCV) infection. METHODS In this phase 2b, randomized, open-label trial of faldaprevir (a protease inhibitor) and deleobuvir (a nonnucleoside polymerase inhibitor), we randomly assigned 362 previously untreated patients with HCV genotype 1 infection to one of five groups: faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg three times daily, plus ribavirin, for 16, 28, or 40 weeks (TID16W, TID28W, or TID40W, respectively); faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg twice daily, plus ribavirin, for 28 weeks (BID28W); or faldaprevir at a dose of 120 mg once daily and deleobuvir at a dose of 600 mg three times daily, without ribavirin, for 28 weeks (TID28W-NR). The primary end point was a sustained virologic response 12 weeks after the completion of therapy. RESULTS The primary end point was met in 59% of patients in the TID16W group, 59% of patients in the TID28W group, 52% of patients in the TID40W group, 69% of patients in the BID28W group, and 39% of patients in the TID28W-NR group. The sustained virologic response 12 weeks after the completion of therapy did not differ significantly according to treatment duration or dosage among ribavirin-containing regimens. This response was significantly higher with TID28W than with TID28W-NR (P=0.03). Rates of a sustained virologic response 12 weeks after the completion of therapy were 56 to 85% among patients with genotype 1b infection versus 11 to 47% among patients with genotype 1a infection and 58 to 84% among patients with IL28B CC versus 33 to 64% with non-CC genotypes. Rash, photosensitivity, nausea, vomiting, and diarrhea were the most common adverse events. CONCLUSIONS The rate of a sustained virologic response 12 weeks after the completion of therapy was 52 to 69% among patients who received interferon-free treatment with faldaprevir in combination with deleobuvir plus ribavirin. (Funded by Boehringer Ingelheim; SOUND-C2 ClinicalTrials.gov number, NCT01132313.).

Safety and efficacy of sorafenib in patients with advanced hepatocellular carcinoma in consideration of concomitant stage of liver cirrhosis.

Goals and Background The multikinase inhibitor sorafenib provides survival benefit for patients with advanced hepatocellular carcinoma (HCC) and liver cirrhosis (LCI) Child-Pugh A. We report our experiences with sorafenib in advanced HCC, particularly in patients with LCI Child-Pugh B/C, where only limited data are available in regard to safety and efficacy of sorafenib. Methods Thirty-four patients with advanced HCC were treated with sorafenib regardless of liver function and prior anticancer therapy. Adverse events (AEs) were graded using Common Toxicity Criteria version 3.0, tumor response was assessed according to Response Evaluation Criteria in Solid Tumors. Results Fifteen patients presented without LCI or with LCI Child-Pugh A, 15/4 patients had LCI Child-Pugh B/C. Barcelona Clinic Liver Cancer stage was B/C/D in 4/22/8 patients. During treatment period (median 2.2 mo), therapy was discontinued in 61.8% of patients due to tumor progression (32.3%), death (17.6%), AEs (8.8%), or noncompliance (2.9%). Most common grade 3/4 AEs included liver dysfunction (23.5%), diarrhea (14.7%), increased lipase (8.8%), fatigue (8.8%), and hand-foot skin reaction (5.9%). Worsening liver dysfunction/failure was more frequent (P=0.036) in patients with LCI Child-Pugh B/C compared with patients with maintained liver function (no LCI/LCI Child-Pugh A). Median overall survival was 7.2 months for patients with maintained liver function versus 3.3/3.4 months for patients with LCI Child-Pugh B/C. Conclusions These data do not support the use of sorafenib in patients with LCI Child-Pugh C, and patients with LCI Child-Pugh B should be treated with caution until larger trials provide more safety data and a clinically relevant survival benefit under sorafenib therapy.

Mycophenolate mofetil as second line therapy in autoimmune hepatitis

INTRODUCTION:In patients with autoimmune hepatitis, efficient immunosuppressive therapy is essential to avoid progression to cirrhosis. There is no established second line therapy for patients failing standard therapy with steroids and azathioprine. The aim of this study was to examine the possible role of mycophenolate mofetil (MMF) as second line treatment of autoimmune hepatitis (AIH).PATIENTS AND ETHODS:We were able to identify 37 patients (29 women, 8 men) with AIH proven according to International AIH Group criteria who failed standard therapy. One patient on MMF was excluded due to non-compliance. A total of 28 of 36 patients had experienced side effects necessitating stop of treatment. One patient stopped azathioprine due to pregnancy. A total of nine patients did not respond sufficiently to azathioprine. A total of four patients with a treatment duration of 3 months or less because of severe side effects were considered as intolerant to MMF. Remission was defined as aspartate transaminase (ASP) < twice upper normal limit (UNL).RESULTS:Of 36 patients on MMF included in the analysis, 14 patients (39%) experienced remission. A total of 22 patients (61%) did not respond sufficiently to MMF. The response rate to MMF was dependent on the cause of treatment cessation of azathioprine. Of eight patients with prior nonresponse to azathioprine, six (75%) did not respond to MMF and only two (25%) reached biochemical remission. Of 28 patients with azathioprine intolerance in 16 (57%) patients, the response to MMF was insufficient and in 12 patients (43%) remission was reached. The difference did not reach statistical significance due to the relatively small numbers included.CONCLUSION:In the light of its good tolerability, MMF seems to be an alternative for patients who could not tolerate azathioprine previously. However, our data suggest that a majority of patients fail MMF particularly if they are switched because of an insufficient response to azathioprine.

Efficacy of the Protease Inhibitor BI 201335, Polymerase Inhibitor BI 207127, and Ribavirin in Patients With Chronic HCV Infection

BACKGROUND & AIMS Therapeutic regimens are being developed for patients with hepatitis C virus (HCV) infection that do not include the combination of peginterferon alfa and ribavirin. We investigated the antiviral effect and safety of BI 201335 (an inhibitor of the NS3/4A protease) and BI 207127 (an inhibitor of the NS5B non-nucleoside polymerase) with ribavirin. METHODS Thirty-two treatment-naïve patients with chronic HCV genotype 1 infection were randomly assigned to groups that were given 400 mg or 600 mg BI 207127 3 times daily plus 120 mg BI 201335 once daily and 1000 to 1200 mg/day ribavirin for 4 weeks. The primary efficacy end point was virologic response (HCV RNA level <25 IU/mL at week 4). Thirty-two patients received treatment; 31 completed all 4 weeks of assigned combination therapy. RESULTS In the group given BI 207127 400 mg 3 times daily, the rates of virologic response were 47%, 67%, and 73% at days 15, 22, and 29; a higher rate of response was observed in patients with genotype-1b compared with genotype-1a infections. In the group given BI 207127 600 mg 3 times daily, the rates of virologic response were 82%, 100%, and 100%, respectively, and did not differ among genotypes. One patient in the group given 400 mg 3 times daily had virologic breakthrough (≥1 log(10) rebound in HCV RNA) at day 22. The most frequent adverse events were mild gastrointestinal disorders, rash, and photosensitivity. There were no severe or serious adverse events; no patients discontinued therapy prematurely. CONCLUSIONS The combination of the protease inhibitor BI 201335, the polymerase inhibitor BI 207127, and ribavirin has rapid and strong activity against HCV genotype-1 and did not cause serious or severe adverse events.

Knockout of myeloid cell leukemia‐1 induces liver damage and increases apoptosis susceptibility of murine hepatocytes

Myeloid cell leukemia‐1 (Mcl‐1) is an antiapoptotic member of the Bcl‐2 protein family. It interacts with proapoptotic Bcl‐2 family members, thereby inhibiting mitochondrial activation and induction of apoptosis. Mcl‐1 is essential for embryonal development and the maintenance of B cells, T cells, and hematopoietic stem cells. We have recently shown that induction of Mcl‐1 by growth factors rescues primary human hepatocytes from CD95‐mediated apoptosis. This prompted us to further analyze the relevance of Mcl‐1 for hepatocellular homeostasis. Therefore, we generated a hepatocyte‐specific Mcl‐1 knockout mouse (Mcl‐1flox/flox‐AlbCre). Deletion of Mcl‐1 in hepatocytes results in liver cell damage caused by spontaneous induction of apoptosis. Livers of Mcl‐1flox/flox‐AlbCre mice are smaller compared to control littermates, due to higher apoptosis rates. As a compensatory mechanism, proliferation of hepatocytes is enhanced in the absence of Mcl‐1. Importantly, hepatic pericellular fibrosis occurs in Mcl‐1 negative livers in response to chronic liver damage. Furthermore, Mcl‐1flox/flox‐AlbCre mice are more susceptible to hepatocellular damage induced by agonistic anti‐CD95 antibodies or concanavalin A. Conclusion: The present study provides in vivo evidence that Mcl‐1 is a crucial antiapoptotic factor for the liver, contributing to hepatocellular homeostasis and protecting hepatocytes from apoptosis induction. (HEPATOLOGY 2009.)

Suppression of Mcl-1 via RNA interference sensitizes human hepatocellular carcinoma cells towards apoptosis induction

BackgroundHepatocelluar carcinoma (HCC) is one of the most common cancers worldwide and a major cause of cancer-related mortality. HCC is highly resistant to currently available chemotherapeutic drugs. Defects in apoptosis signaling contribute to this resistance. Myeloid cell leukemia-1 (Mcl-1) is an anti-apoptotic member of the Bcl-2 protein family which interferes with mitochondrial activation. In a previous study we have shown that Mcl-1 is highly expressed in tissues of human HCC. In this study, we manipulated expression of the Mcl-1 protein in HCC cells by RNA interference and analyzed its impact on apoptosis sensitivity of HCC cells in vitro.MethodsRNA interference was performed by transfecting siRNA to specifically knock down Mcl-1 expression in HCC cells. Mcl-1 expression was measured by quantitative real-time PCR and Western blot. Induction of apoptosis and caspase activity after treatment with chemotherapeutic drugs and different targeted therapies were measured by flow cytometry and fluorometric analysis, respectively.ResultsHere we demonstrate that Mcl-1 expressing HCC cell lines show low sensitivity towards treatment with a panel of chemotherapeutic drugs. However, treatment with the anthracycline derivative epirubicin resulted in comparatively high apoptosis rates in HCC cells. Inhibition of the kinase PI3K significantly increased apoptosis induction by chemotherapy. RNA interference efficiently downregulated Mcl-1 expression in HCC cells. Mcl-1 downregulation sensitized HCC cells to different chemotherapeutic agents. Sensitization was accompanied by profound activation of caspase-3 and -9. In addition, Mcl-1 downregulation also increased apoptosis rates after treatment with PI3K inhibitors and, to a lower extent, after treatment with mTOR, Raf I and VEGF/PDGF kinase inhibitors. TRAIL-induced apoptosis did not markedly respond to Mcl-1 knockdown. Additionally, knockdown of Mcl-1 efficiently enhanced apoptosis sensitivity towards combined treatment modalities: Mcl-1 knockdown significantly augmented apoptosis sensitivity of HCC cells towards chemotherapy combined with PI3K inhibition.ConclusionOur data suggest that specific downregulation of Mcl-1 by RNA interference is a promising approach to sensitize HCC cells towards chemotherapy and molecularly targeted therapies.

Apoptosis in liver disease.

Abstract: The description of the morphological hallmarks of programmed cell death, apoptosis, in 1972 by Kerr, Wyllie and Currie started a field of research that revolutionized our understanding of cellular proliferation, tissue homeostasis and pathophysiology of many diseases. In the following years, a series of proteins involved in signaling and intracellular death pathways were identified and 30 years later the Noble Prize for physiology and medicine was awarded to S. Brenner, H. R. Horvitz and J. E. Sulston for their discoveries related to describing the mechanisms of cell death (apoptosis). The delineation of the signaling pathways that mediate apoptosis changed the paradigms of understanding in many liver diseases. The most detailed analyzed mode of apoptosis involves a cell surface‐based receptor–ligand system. Death receptors are typically members of the tumor necrosis factor‐receptor superfamily and comprise an intracellular death domain. Following ligand binding to the receptor, intracellular adapter molecules are recruited to the receptor and subsequently transmit the apoptotic signal. Intracellular organelle‐dependent signaling occurs, and effector molecules then augment the receptor‐initiated apoptosis process. Cell death and degradation follows the activation of a highly regulated set of cytosolic and nuclear proteases and DNAses. Receptor‐independent activation of the apoptotic process can occur as part of the cytotoxicity related to UV radiation, chemotherapeuticals or other DNA‐damaging agents through activation of intracellular sensors of cellular integrity, e.g. the tumor suppressor gene p53. In contrast to necrosis, apoptosis is not commonly accompanied by an inflammatory response that causes collateral cell damage. The apoptotic program is highly effective in eliciting cell death and thus must be tightly controlled. This is achieved through continuous integration of pro‐ and antiapoptotic signals at the individual cell level. Dysregulation of the apoptotic process, resulting in too much or too little cell death, has potentially devastating effects and has been implicated in many forms of liver disease like acute liver failure or hepatocellular carcinoma. This review will focus initially on recent progress in signaling events of hepatocellular apoptosis and subsequently discuss the consequences for the hepatic pathophysiology that involves disarrangement of hepatocellular apoptosis.

Cell death and hepatocarcinogenesis: Dysregulation of apoptosis signaling pathways

Hepatocellular carcinoma (HCC) remains a disease with a poor prognosis despite recent advances in the pathophysiology and treatment. Although the disease is biologically heterogeneous, dysregulation of cellular proliferation and apoptosis both occur frequently and contribute to the malignant phenotype. Chronic liver disease is associated with intrahepatic inflammation which promotes dysregulation of cellular signaling pathways; this triggers proliferation and thus lays the ground for expansion of premalignant cells. Cancer emerges when immunological control fails and transformed cells develop resistance against cell death signaling pathways. The same mechanisms underlie the poor responsiveness of HCC towards chemotherapy. Only recently advances in understanding the signaling pathways involved has led to the development of an effective pharmacological therapy for advanced disease. The current review will discuss apoptosis signaling pathways and focus on apoptosis resistance of HCC involving derangements in cell death receptors (e.g. tumor necrosis factor‐alpha [TNF], CD95/Apo‐1, TNF‐related apoptosis‐inducing ligand [TRAIL]) and associated adapter molecules (e.g. FADD and FLIP) of apoptotic signaling pathways. In addition, the role of the transcription factor nuclear factor‐kappaB (NFκB) and members of the B cell leukemia‐2 (Bcl‐2) family that contribute to the regulation of apoptosis in hepatocytes are discussed. Eventually, the delineation of cell death signaling pathways could contribute to the implementation of new therapeutic strategies to treat HCC.