Sitafloxacin for Third-Line Helicobacter pylori Eradication: A Systematic Review

Background and Aim: Sitafloxacin-based therapy is a potent candidate for third-line Helicobacter pylori eradication treatment. In this systematic review, we summarise current reports with sitafloxacin-based therapy as a third-line treatment. Methods: Clinical studies were systematically searched using PubMed, Cochrane library, Web of Science, and the Igaku-Chuo-Zasshi database. We combined data from clinical studies using a random-effects model and calculated pooled event rates, 95% confidence intervals (CIs), and the pooled odds ratio (OR). Results: We included twelve clinical studies in the present systematic review. The mean eradication rate for 7-day regimens of either PPI (proton pump inhibitor) or vonoprazan–sitafloxacin–amoxicillin was 80.6% (95% CI, 75.2–85.0). The vonoprazan–sitafloxacin–amoxicillin regimen was significantly superior to the PPI–sitafloxacin–amoxicillin regimen (pooled OR of successful eradication: 6.00; 95% CI: 2.25–15.98, p < 0.001). The PPI–sitafloxacin–amoxicillin regimen was comparable with PPI–sitafloxacin–metronidazole regimens (pooled OR: 1.06; 95% CI: 0.55–2.07, p = 0.86). Conclusions: Although the 7-day regimen composed of vonoprazan, sitafloxacin, and amoxicillin is a good option as the third-line Helicobacter pylori eradication treatment in Japan, the extension of treatment duration should be considered to further improve the eradication rate. Considering the safety concern of fluoroquinolones, sitafloxcin should be used after confirming drug susceptibility.


Search Strategy
Relevant reports were systematically searched using PubMed, Cochrane library, Web of Science, and Igaku-Chuo-Zasshi database in Japan (up to May 2021) [30]. The search words used were as follows: (sitafloxacin OR DU-6859a OR Gracevit) AND (Helicobacter pylori OR H. pylori OR Helicobacter infection) AND (eradication OR treatment OR therapy). There was no language limitation applied.

Data Extraction
The following data were extracted from all included studies: principal author, publishing year, study type, drugs and doses for H. pylori eradication regimens, duration of treatment, the number of enrolled subjects, diagnostic methods employed for testing H. pylori infection after eradication, and key outcome data such as eradication rates, as well as the occurrence of diarrhoea and severe adverse events. The eligibility of all articles was independently examined by two reviewers (T.N. and M.M.). Disagreements were resolved by consulting a third reviewer (O.T.).

Assessment of Methodological Quality
We evaluated the quality of enrolled studies using the Jadad scale [31] for RCTs or by the Quality Assessment Tool for Case Series Studies (QATCSS) of the National Institutes of Health for nonrandomised, open label studies (National Heart, Lung, and Blood Institute. Available from: https://www.nhlbi.nih.gov/health-pro/guidelines/indevelop/cardiovascular-risk-reduction/tools/case_series, accessed on 1 May 2021) for nonrandomised studies. Two reviewers (T.N. and H.E.) assessed the quality of the included studies.

Statistical Analysis
Statistical analysis was performed using Comprehensive Meta-Analysis (CMA) software (version 3, Biostat, Inc., Englewood, NJ, USA) and Review Manager (RevMan; The Cochrane Collaboration, 2008; The Nordic Cochrane Centre, Copenhagen, Denmark) [32]. Pooled event rates and 95% confidence intervals (CIs) were calculated using a randomeffects model. The odds ratio (OR) for successful eradication was calculated using the random-effects model and the Mantel-Haenszel method [33]. Heterogeneity between studies was assessed by Cochran's Q and I 2 tests [7]. p-value < 0.1 was considered as significant heterogeneity, as the power of the Q test is low. An I 2 score ≥ 50% was considered a moderate level of heterogeneity [34].

Search Results
The systematic review process identified 248 potential reports ( Figure 1). Based on the exclusion criteria, we then excluded 230 studies (32 duplications, 25 unrelated topics, 63 review articles, 18 protocols for clinical trials, 90 meeting abstracts, and 2 case reports). The remaining 18 studies were scrutinised, and six additional studies were rejected. In four studies, the sitafloxacin-containing regimen was used as first-line or second-line treatment for subjects with penicillin allergy [35][36][37][38]. One study combined the eradication rates of levofloxacin-based and sitafloxacin-based therapy [39]. One study combined the eradication rates of first, second, and third-line therapy [9]. Finally, we included 12 clinical studies in the present systematic review [16,[18][19][20][21][22][23][24][25][26][27]40]. The included studies were all performed in Japan. In Sugimoto  The systematic review process identified 248 potential reports (Figure 1). the exclusion criteria, we then excluded 230 studies (32 duplications, 25 unrelat 63 review articles, 18 protocols for clinical trials, 90 meeting abstracts, and 2 cas The remaining 18 studies were scrutinised, and six additional studies were re four studies, the sitafloxacin-containing regimen was used as first-line or se treatment for subjects with penicillin allergy [35][36][37][38]. One study combined the er rates of levofloxacin-based and sitafloxacin-based therapy [39]. One study com eradication rates of first, second, and third-line therapy [9]. Finally, we included studies in the present systematic review [16,[18][19][20][21][22][23][24][25][26][27]40]. The included studies we formed in Japan. In Sugimoto et al.'s, Saito et al.'s and Sue et al.'s studies, the therapy was the 7-day regimen with vonoprazan or PPI, clarithromycin 200 mg b.i.d., and amoxicillin 750 mg b.i.d., and the second-line therapy was the 7-day with vonoprazan or PPI, metronidazole 250 mg b.i.d., and amoxicillin 750 m another eight studies, the first-line therapy was the 7-day regimen with PPI, cla cin, and amoxicillin, and the second-line therapy was the 7-day regimen with P nidazole, and amoxicillin. In all included studies, the sitafloxacin dose was 100  Table 1 summarises the efficacy of PPI-sitafloxacin-amoxicillin, which is the order of treatment duration and amoxicillin dose employed. The 1500 mg/d cillin dose was administered as 750 mg b.i.d., while the 2000 mg/day was admin 500 mg q.i.d. Prolonged treatment durations appeared to improve eradication ra ever, in an RCT comparing 7-day and 14-days regimens, Furuta et al. found no s difference [23]. Furthermore, Mori et al. compared 7-day and 10-days regimen served was no significant difference [25].  Table 1 summarises the efficacy of PPI-sitafloxacin-amoxicillin, which is sorted in the order of treatment duration and amoxicillin dose employed. The 1500 mg/day amoxicillin dose was administered as 750 mg b.i.d., while the 2000 mg/day was administered as 500 mg q.i.d. Prolonged treatment durations appeared to improve eradication rates. However, in an RCT comparing 7-day and 14-days regimens, Furuta et al. found no significant difference [23]. Furthermore, Mori et al. compared 7-day and 10-days regimens and observed was no significant difference [25].

Efficacy of PPI-Sitafloxacin-Metronidazole
Several studies evaluated the efficacy of the PPI-sitafloxacin-metronidazole regimen. Table 3 summarises these results and is organised in the order of treatment duration. Furuta et al. compared 7-day and 14-days regimens in an RCT and observed no significant difference [23]. Several studies evaluated the efficacy of th men. Table 3 summarises these results and is orga Furuta et al. compared 7-day and 14-days regimen difference [23].

Quality Assessment
Quality assessment is reported in Table 4. A maximum score of 5 was obtained using the Jadad scale, whereas a maximum score of 9 was attained with QATCSS. In general, the quality of the included studies was good, apart from the study by Tokunaga et al. Figure 5 shows the forest plot of adverse event (diarrhoea) associated with 7-day regimens composed of PPIs or vonoprazan-sitafloxacin-amoxicillin. The pooled adverse event (diarrhoea) rate was 24.4% (95% CI: 16.7-34.3%). The frequency of diarrhoea ranged between 12.5% and 50.0%. Sue et al. reported two cases (6.1%) presenting severe allergy. Other studies did not report any severe adverse events.

Quality Assessment
Quality assessment is reported in Table 4. A maximum score of 5 was obtained using the Jadad scale, whereas a maximum score of 9 was attained with QATCSS. In general, the quality of the included studies was good, apart from the study by Tokunaga et al. Single center open label study -8 *: Jadad scale reached a maximum score of 5. † : Quality assessment tool for case series studies (QATCSS) reaches a maximum score of 9.

Discussion
The 7-day regimen composed of vonoprazan, sitafloxacin, and amoxicillin is considered as a good option for the third-line H. pylori eradication treatment in Japan.
An in vitro study has reported that sitafloxacin and metronidazole exhibit a synergistic antimicrobial activity, while sitafloxacin and amoxicillin failed to demonstrate such

Discussion
The 7-day regimen composed of vonoprazan, sitafloxacin, and amoxicillin is considered as a good option for the third-line H. pylori eradication treatment in Japan.
An in vitro study has reported that sitafloxacin and metronidazole exhibit a synergistic antimicrobial activity, while sitafloxacin and amoxicillin failed to demonstrate such activity [41]. Several RCTs have compared PPI-sitafloxacin-metronidazole with PPI-sitafloxacin-amoxicillin [23,24]. This meta-analysis confirmed that the efficacy of PPI-sitafloxacin-amoxicillin was comparable with that of PPI-sitafloxacin-metronidazole. The PPI-sitafloxacin-metronidazole regimen is a good option in patients presenting penicillin allergy [36,38].
In PPI-sitafloxacin-amoxicillin, amoxicillin is administered at quantities of 1500 mg/day (750 mg b.i.d.), or 2000 mg/day (500 mg q.i.d.). The bactericidal effect of amoxicillin depends on the time above the minimum inhibitory concentration (MIC), as amoxicillin has minimal post-antibiotic effect [42,43]. Furuta et al. compared amoxicillin 750 mg b.i.d., 500 mg t.i.d., and 500 mg q.i.d. in a PPI-metronidazole-amoxicillin regimen, and reported eradication rates of 80.5%, 90.5%, and 95.2%, respectively, indicating that four times daily amoxicillin dosing maximised the eradication rate [44]. This study indicated that the optimal amoxicillin dose was 2000 mg/day (500 mg q.i.d.). The amoxicillin dose in the vonoprazan-sitafloxacin-amoxicillin regimen needs to be further investigated in future studies.
Regarding the optimal duration for H. pylori eradication therapy, a meta-analysis showed that increasing the duration of PPI-based triple therapy increased the eradication rates [45]. There are many reports that the eradication rates of fluoroquinolone-based therapy were increased by extending the duration to 14 days [46][47][48][49][50][51][52]. Conversely, Furura et al. compared 7-day and 14-days regimens of PPI-sitafloxacin-amoxicillin in their RCT, and found no significant difference. Mori et al. also compared 7-day and 10-days regimens of PPI-sitafloxacin-amoxicillin, and found no significant difference. However, the number of patients was limited, and hence these studies might be underpowered. As for the vonoprazan-sitafloxacin-amoxicillin regimen, there is no data other than 7-days regimen. The 14-day regimen with vonoprazan-sitafloxacin-amoxicillin may achieve excellent eradication rates. The optimal duration of the vonoprazan-sitafloxacin-amoxicillin regimen needs to be further investigated in future studies.
In Japan, the primary resistance of H. pylori to levofloxacin is 15% [1]. In contrast, the sitafloxacin resistance rates reported in the included studies ranged between 21.7% and 60.3%; these resistance rates were relatively high. This could be attributed to the fact that patients who failed to demonstrate successful eradication twice might have a history of prior antibiotic use, including fluoroquinolones for non-eradication purposes [53,54]. Fluoroquinolone resistance is caused by gyrA mutation [55][56][57][58]. Three studies reported both sitafloxacin resistance rates and gyrA mutation rates. Accordingly, the sitafloxacin resistance rates and gyrA mutation rates were 42.5% and 55.1% in Matsuzaki et al.'s study [21], 58.7% and 60.3% in Mori et al.'s 2016 study [24], and 50.0% and 50.0% in Mori et al.'s 2020 study [25]. When the sitafloxacin resistance was defined as MIC, the sitafloxacin resistance rate was found to be similar to the gyrA mutation rate. Eradication rates for gyrA mutation-negative and mutation-positive groups were 96.7% and 74.4% in Matsuzaki et al.'s study [21], 100% and 70.3% in Mori et al.'s 2016 study [24], and 89.5% and 68.4% in Mori et al.'s 2020 study, respectively [25]. Sitafloxacin-based triple therapy showed excellent eradication rates for gyrA mutation-negative H. pylori. Sitafloxacin-based therapy should be used for sitafloxacin susceptible or gyrA mutation-negative H. pylori. Sitafloxacin resistant or gyrA mutation-positive H. pylori would require alternate treatments such as rifabutin-based therapy [13,[59][60][61].
The United States Food and Drug Administration recently enhanced warnings about disabling and potentially permanent side effects involving the tendons, muscles, joints, nerves, and central nervous system [62]. Balancing risk and benefit should be considered.
Our systematic review has several limitations. The included studies were all from Japan, as sitafloxacin is only available in Japan and Thailand. The availability of vonoprazan is also limited. In Japan, the first-line regimen is PPI-clarithromycin-amoxicillin and the second-line regimen is PPI-metronidazole-amoxicillin. Therefore, the results of the current study may not directly applicable to the populations who were administered bismuth containing regimens as first-line or second-line regimens. Therefore, these results may not be generalisable to other ethnicities and countries.
In conclusion, the 7-day regimen with vonoprazan 20 mg b.i.d., sitafloxacin 100 mg b.i.d., and amoxicillin 750 mg b.i.d. or 500 mg q.i.d. is a good option as the third-line H. pylori eradication treatment, at least in Japan. However, the extension of treatment duration should be considered to further improve the eradication rate. Considering the safety concern of fluoroquinolones, sitafloxcin should be used after confirming drug susceptibility.