Masao Omata

Dr. Masao Omata


Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 September 2014 in Journal of Viral Hepatitis
Verified
Journal Article
Open access
PDF file
MOMasao Omata
Masao Omata
SNShuhei Nishiguchi
Shuhei Nishiguchi
YUYoshiyuki Ueno
Yoshiyuki Ueno
HMHitoshi Mochizuki
Hitoshi Mochizuki
NINamiki Izumi
Namiki Izumi
MMMasashi Mizokami
Masashi Mizokami
Summary: Genotype 2 hepatitis C virus (HCV) accounts for up to 30% of chronic HCV infections in Japan. The standard of care for patients with genotype 2 HCV – peginterferon and ribavirin for 24 weeks – is poorly tolerated, especially among older patients and those with advanced liver disease. We conducted a phase 3, open‐label study to assess the efficacy and safety of an all‐oral combination of the NS5B polymerase inhibitor sofosbuvir and ribavirin in patients with chronic genotype 2 HCV infection in Japan. We enrolled 90 treatment‐naïve and 63 previously treated patients at 20 sites in Japan. All patients received sofosbuvir 400 mg plus ribavirin (weight‐based dosing) for 12 weeks. The primary endpoint was sustained virologic response at 12 weeks after therapy (SVR12). Of the 153 patients enrolled and treated, 60% had HCV genotype 2a, 11% had cirrhosis, and 22% were over the aged 65 or older. Overall, 148 patients (97%) achieved SVR12. Of the 90 treatment‐naïve patients, 88 (98%) achieved SVR12, and of the 63 previously treated patients, 60 (95%) achieved SVR12. The rate of SVR12 was 94% in patients with cirrhosis and in those aged 65 and older. No patients discontinued study treatment due to adverse events. The most common adverse events were nasopharyngitis, anaemia and headache. Twelve weeks of sofosbuvir and ribavirin resulted in high rates of SVR12 in treatment‐naïve and previously treated patients with chronic genotype 2 HCV infection. The treatment was safe and well tolerated by patients, including the elderly and those with cirrhosis.

4 February 2022 in Hepatology International
Verified
Journal Article
Open access
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HYHong You
Hong You
XMXiong Ma
Xiong Ma
CECumali Efe
Cumali Efe
GWGui-Qiang Wang
Gui-Qiang Wang
SJSook-Hyang Jeong
Sook-Hyang Jeong
JJJidong Jia
Jidong Jia

1 March 2012 in Hepatology International
Verified
Journal Article
Closed access
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MOMasao Omata
Masao Omata
Tatsuo KandaTatsuo Kanda
Tatsuo Kanda
MYMing-Lung Yu
Ming-Lung Yu
OYOsamu Yokosuka
Osamu Yokosuka
SLSeng-Gee Lim
Seng-Gee Lim
GMGeoff McCaughan
Geoff McCaughan

20 September 2019 in Hepatology International
Verified
Journal Article
Open access
PDF file
Tatsuo KandaTatsuo Kanda
Tatsuo Kanda
GLGeorge K. K. Lau
George K. K. Lau
LWLai Wei
Lai Wei
MMMitsuhiko Moriyama
Mitsuhiko Moriyama
MING-LUNG YuMING-LUNG Yu
MING-LUNG Yu
MOMasao Omata
Masao Omata
In the direct-acting antiviral (DAA) era for hepatitis C virus (HCV) infection, sustained virological response (SVR) is very high, but close attention must be paid to the possible occurrence of hepatocellular carcinoma (HCC) and reactivation of hepatitis B virus (HBV) in patients with co-infection who achieved SVR in short term. HCC occurrence was more often observed in patients with previous HCC history. We found occurrence of HCC in 178 (29.6%) of 602 patients with previous HCC history (15.4 months mean follow-up post-DAA initiation) but, in contrast, in only 604 (1.3%) of 45,870 patients without previous HCC history (18.2 months mean follow-up). Thus, in these guidelines, we recommend the following: in patients with previous HCC history, surveillance at 4-month intervals for HCC by ultrasonography (US) and tumor markers should be performed. In patients without previous HCC history, surveillance at 6- to 12-month intervals for HCC including US is recommended until the long-term DAA treatment effects, especially for the resolution of liver fibrosis, are confirmed. This guideline also includes recommendations on how to follow-up patients who have been infected with both HCV and HBV. When HCV was eradicated in these HBsAg-positive patients or patients with previous HBV infection (anti-HBc and/or anti-HBs-positive), it was shown that HBV reactivation or HBV DNA reappearance was observed in 67 (41.4%) of 162 or 12 (0.9%) of 1317, respectively. For these co-infected patients, careful attention should be paid to HBV reactivation for 24 weeks post-treatment.

1 August 2012 in Seminars in Oncology
Verified
Journal Article
Closed access
RMRyota Masuzaki
Ryota Masuzaki
SKSeth J. Karp
Seth J. Karp
MOMasao Omata
Masao Omata

26 May 2016 in Hepatology International
Verified
Journal Article
Open access
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MOMasao Omata
Masao Omata
Tatsuo KandaTatsuo Kanda
Tatsuo Kanda
LWLai Wei
Lai Wei
MING-LUNG YuMING-LUNG Yu
MING-LUNG Yu
WCWang-Long Chuang
Wang-Long Chuang
SSShiv Kumar Sarin
Shiv Kumar Sarin
The Asian Pacific Association for the Study of the Liver (APASL) convened an international working party on “APASL consensus statements and recommendations for management of hepatitis C” in March 2015 to revise the “APASL consensus statements and management algorithms for hepatitis C virus infection” (Hepatol Int 6:409–435, 2012). The working party consisted of expert hepatologists from the Asian–Pacific region gathered at the Istanbul Congress Center, Istanbul, Turkey on 13 March 2015. New data were presented, discussed, and debated during the course of drafting a revision. Participants of the consensus meeting assessed the quality of the cited studies. The finalized recommendations for hepatitis C prevention, epidemiology, and laboratory testing are presented in this review.