Understanding FDA Approval of Vonoprazan-Based Therapies for Helicobacter Pylori

Pharmacy Times (5/4/22): FDA Approves Pair of Vonoprazan Treatments for Helicobacter Pylori Infection

“The (FDA) has approved 2 vonoprazan-based medications for the treatment of Helicobacter pylori (H. pylori) infection.

Phathom Pharmaceuticals announced the approvals of both the Voquezna Triple Pak (vonoprazan, amoxicillin, clarithromycin) and Voquezna Dual Pak (vonoprazan, amoxicillin) based on positive safety and efficacy data from the phase 3 PHALCON-HP trial.”

WD Chey et al. Gastroenterol 2022; 163: 608-619. Open Access! Vonoprazan Triple and Dual Therapy for Helicobacter pylori Infection in the United States and Europe: Randomized Clinical Trial

Key findings from this randomized, controlled trial with treatment-naive 1046 adults:

  • In all patients, vonoprazan triple and dual therapy were superior to lansoprazole triple therapy (80.8% and 77.2%, respectively, vs 68.5% (both superior)
  • In patients with clarithromycin resistance, vonoprazan triple therapy was effective in 65.8%, dual therapy in 69.6%, vs lansoprazole triple therapy 31.9% (both superior)
  • Vonoprazan increases intragastric pH rapidly “and maintains it to a greater degree than PPI; this has been associated with higher H pylori eradication rates” (in prior studies as well)

The associated editorial: CA Fallone (Open Access!) The Current Role of Vonoprazan in Helicobacter pylori Treatment

Based on this new information, the author proposes the treatment algorithm below and notes that “the role of increased acid suppression by PPI substitution with vonoprazan should be examined in other H pylori regimens.” The author favors bismuth quadruple therapy in those with clarithromycin resistance as non-bismuth quadruple therapy utilizes an unnecessary antibiotic (clarithromycin).

Other points:

  • Metronidazole resistance is fairly common, but bismuth quadruple therapy can overcome much of the metronidazole resistance
  • Levofloxacin resistance is quite high in certain regions and should only be used with caution, given recent warnings from the US Food and Drug Administration of aortic rupture in susceptible individuals
  • Rifabutin can cause some bone marrow suppression

My take: With the more widespread availability of susceptiblity testing (beyond clarithromycin), I anticipate more targeted treatments. At the same time, vonoprazan-based treatments are likely to be important in increasing eradication rates.

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Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Position Paper for Pediatric Breath Testing

IJ Broekaert et al. JPGN 2022; 74: 123-127. Open access: An ESPGHAN Position Paper on the Use of Breath Testing in Paediatric Gastroenterology

This is a good article which provides pediatric dosing of breath testing agents and important considerations in methodology and interpretation. In addition, there are 22 graded recommendations (see below) –some may be surprising. For example, the breath testing is NOT recommended for diagnosis of H pylori but is recommended for determination of eradication therapy.

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How To Achieve Helicobacter Pylori Cure Rates of >95%

Related to yesterday’s blog, here is an SNL commercial for the “Koohl” toilet (also with Benedict Cumberbatch) in 2016: SNL Koohl Toilet

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DY Graham, SF Moss. Am J Gastroenterol 2022. 117: 524-528. Antimicrobial Susceptibility Testing for Helicobacter pylori Is Now Widely Available: When, How, Why

Key points:

  • Susceptibility testing for H pylori is widely available in the U.S. and should help optimize treatments to get success rates >95%. Testing is now available for the most common treatment antibiotics: amoxicillin, metronidazole, tetracycline, levofloxacin, clarithromycin, and rifabutin.
  • Handling/shipping specimens properly is important with susceptibility testing
  • The authors recommend a PPI which is minimally-affected by CYP2C19 metabolism, namely rabeprazole or esomeprazole.
  • Provide careful instructions to patient/family regarding treatment

Susceptibility Testing Labs (see Table 1):

  • Quest: Our Quest representative indicated code: 36994 (H. pylori culture with reflex to susceptibility). Preferred Specimen: 3 mm Gastric/Antral or Duodenal biopsy collected in Brucella broth or Trypticase Soy Broth (TSB) with 10-20% glycerol
  • LabCorp: Helicobacter pylori Culture Test Code Test Code 180885
  • ARUP: Helicobacter pylori Culture Test Code 2006686
  • Culture (Catalog HELIS) or Stool PCR testing (Catalog HPFRP) can be done by Mayo Clinic
  • Reflex stool testing as well as PCR gastric testing from formalin is available through by American Molecular laboratories

A treatment algorithm is listed:

  • In the absence of highly effective empiric treatment or after treatment failure, the authors recommend susceptibility testing.
  • If clarithromycin susceptible, then a 14-day clarithromycin triple therapy course is recommended
  • If clarithromycin resistant but metronidazole susceptible, then 14-day metronidazole triple therapy
  • If resistant to both clarithromycin and metronidazole, then either a 14-day bismuth quadruple therapy, or a rifabutin triple therapy are preferred. However, if H pylori organisms are levofloxacin susceptible, then 14-day levofloxacin triple therapy may be a good option.
  • The authors recommend quinolone therapy only in the setting of susceptibility testing due to the FDA warnings about long-term adverse effects.

My take: Perhaps H pylori susceptibility testing availability needs to be a quality metric for hospitals and endoscopy centers.


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Next-Generation Treatment for H Pylori

KG Hulten, et al. Gastroenterol 2021; 11: 1433-1442. Open Access: Comparison of Culture With Antibiogram to Next-Generation Sequencing Using Bacterial Isolates and Formalin-Fixed, Paraffin-Embedded Gastric Biopsies

Background: “The general unavailability of culture-based susceptibility testing for H pylori has resulted in the almost universal reliance on hopeful (empiric) therapy and a high proportion of treatment failures.” Besides the lack of availability of culture-based susceptibility testing, the global increase in prevalence of antimicrobial resistance contributes to the poor cure rates obtained with empiric use of the currently most popular triple therapies for H pylori infection.

Methods: H pylori isolates (n=170) (clinical isolates and formalin-fixed, paraffin-embedded) were tested for susceptibility to amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and rifabutin using agar dilution and NGS targeted to 23S rRNAgyrA16S rRNApbp1rpoB and rdxA. Agreement was quantified using κ statistics.

Key findings:

  • Agreement between agar dilution and NGS from culture isolates was very good for clarithromycin (κ = 0.90012), good for levofloxacin (κ = 0.78161) and fair for metronidazole (κ = 0.55880), and amoxicillin (κ = 0.21400)
  • Comparison of NGS from tissue blocks and agar dilution from isolates from the same stomachs demonstrated good accuracy to predict resistance for clarithromycin (94.1%), amoxicillin (95.9%), metronidazole (77%), levofloxacin (87.7%), and tetracycline (98.2%)

Associated editorial: F Megraud et al. Gastroenterol 2021; 11: 1367-1369. Open Access: Molecular Diagnosis for Helicobacter pylori . . . at Last

Excerpts from editorial:

  • “By targeting all of the genes responsible for antibiotic resistance, it is possible to obtain genotypic susceptibility data for all of the antibiotics of potential use, without the need to perform” culture and antibiotic susceptibility testing
  • “Hulten et al show not only that they obtained comparable results with the reference method (phenotypic) for most of the antibiotics, but also that NGS can also be performed on both culture isolates and stored histologic preparations. This result is important because it avoids the need for extra biopsies and culture”
  • “NGS could also be applied on stools. In this particular environment where H pylori DNA is found in a low amount, excellent DNA extraction methods are mandatory and progress is being made in this field”

My take: NGS can bring H pylori treatment to a new era (like almost all other infections). “Molecular methods can potentially augment or even replace the current in vitro methods for susceptibility testing, which are cumbersome, technically challenging, and time-consuming.”

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Lots of Room to Improve with H pylori Treatment

Briefly noted: A recent survey study (N Du et al. JPGN Reports: 2021; 2: p e033. doi: 10.1097/PG9.0000000000000033. Full Text: Assessment of Community Pediatric Providers’ Approach to Children With Helicobacter pylori) found that pediatric providers had poor knowledge and/or adherence to pediatric H pylori guidelines.

Key findings:

  • Over a third of the respondents reported incorrectly testing patients for H. pylori while they were taking proton pump inhibitors.
  • 17% (n=17) incorrectly preferred blood serology as testing modality
  • 63% (n=64) relied on symptom resolution as indication of cure

My take: It would be interesting to compare pediatric gastroenterology provider responses to general pediatric providers. It is likely that a much higher percentage would be following established guidelines. One area of the guidelines that I think should be changed would be encouraging increased use of quadruple therapy in children, especially if resistance testing is not performed; this change would better align with adult guidelines. In adults, quadruple therapy has been associated with increased cure rates.

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Rifabutin-based Triple Therapy for H pylori

From NEJM Journal Watch (5/8/20): A New First-Line Treatment Regimen for H. pylori Infection

In this industry-funded, phase III trial conducted in the U.S., 455 H. pylori-treatment–naive patients with dyspepsia and a confirmed H. pylori diagnosis were randomized to treatment with capsules containing rifabutin, amoxicillin, and omeprazole or capsules containing amoxicillin and omeprazole for 14 days. Participants took 4 capsules every 8 hours. The eradication rate in the rifabutin-based therapy group was significantly higher (84%) compared with the comparison group (58%). In patients with confirmed adherence to treatment, the eradication rates were 90% versus 65%, respectively. No H. pylori resistance to rifabutin was detected, and side effects were similar between groups.

My take: More treatment options are needed due to drug resistance.  Also, “further studies are needed to compare this new triple therapy with current quadruple therapies.”

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Treating Helicobacter Pylori Lowers The Risk of Gastric Cancer

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Helicobacter Pylori 2019 Review

A recent review (SE Crowe. NEJM 2019; 1158-65) provides a succinct summary of current H pylori management.

A couple of key points:

  • It is essential to test for cure after treatment 1 month afterwards
  • If retreatment is needed, use an alternative regimen
  • In the discussion of treatment, Dr. Crowe does NOT emphasize quadruple therapy except in individuals with a clarithromycin resistance probability of >25% (based on geographic incidence rates) or prior macrolide use.  She notes that in some populations that clarithromycin-based triple therapy had similar effectiveness as bismuth-based quadruple-based therapy.  Table 2 lists the 7 ACG approved treatment regimens.
  • It is noted that U.S. clarithromycin-resistance is between 21-30%.

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Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

It is Getting Harder to Treat H pylori -Here’s Why

In a recent study (A Savoldi et al. Gastroenterol 2018; 155: 1372-82, editorial pg 1287), the authors conducted a systematic review and meta-analysis to examine the prevalence of antibiotic resistance to Helicobacter pylori. The authors identified 178 studies with 66,142 H pylori isolates. Tables 2 & 3 provide comprehensive data.

Key points:

  • In the Americas region, primary resistance to clarithromycin, metronidazole, levofloxacin and amoxicillin was 10%, 23%, 15%, and 10% respectively.
  • In the European region, primary resistance to clarithromycin, metronidazole, levofloxacin and amoxicillin was 18%, 32%, 11%, and 0% respectively.

Antibiotic resistance is increasing: 

  • In the Americas region, resistance in 2006-2008 compared to 2012-201 for clarithromycin, & metronidazole: 11%–>20%, 26%–>29% respectively.
  • In the European region, resistance in 2006-2008 compared to 2012-201 for clarithromycin, & metronidazole: 28%–>28%, 38%–>46% respectively.
  • “The resistance rates to clarithromycin, metronidazole, and levofloxacin have increased over time in all WHO regions.”  Other regions with data in study included Eastern Mediterranean, Southeast Asia, and Western Pacific.
  • In the study, the authors also “describe a clear significant association between antibiotic resistance and treatment failure.”

In their discussion, the authors note that the incidence of gastric cancer is higher in areas with increased antibiotic resistance.  Though there has been a decline in gastric cancer, “based on our data, we can hypothesize that this trend in reduction is expected to revert soon because available treatment can no longer guarantee a satisfactory eradication rate.”

From editorial:

  • H pylori is not one of those bacteria in which resistance develops as an epidemic by horizonatal transfer of mobile genetic elements…Resistance in H pylori only occurs unevenly by mutations…Fortunately, resistance occurs “very seldomly for …amoxicillin and tetracycline.”
  • Treatment failure is “almost 7 times greater (6.97) when the strain is clarithromycin resistant and even greater (8.18) when the strain is levofloxacin resistant.” Resistance to metronidazole confers a lesser degree of treatment failure risk: OR 2.52.

My take: This study provides some sobering news about H pylori prevalence and how it is becoming more difficult to treat.

Related blog posts:

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Pooled Prevalence of resistance to clarithromycin (2006-2016). This is from Figure 2. Sections B & C (not shown) provide similar graphic info for metronidazole and levofloxacin

The Rise of Eosinophilic GI Diseases –Not Likely Connected to Helicobacter Pylori

A recent prospective case-control study (J Molina-Infante et al. Am J Gastroenterol 2018; 113: 972-9 -thanks to Ben Gold for this reference) examined the potential connection between Helicobacter pylori and eosinophilic GI diseases.  They examined 808 individuals (404 cases of eosinophilic esophagitis [EoE], 404 controls). Key findings:

  • H pylori prevalence was not different between cases and controls (37% vs. 40%, odds ratio 0.97).  The authors conclude that H pylori which has declined in prevalence globally is not inversely associated with EoE as had been suggested in some previous reports

In an associated editorial, (pg 941-4), the authors note that there has been a dramatic increase in atopic diseases over the past 30 years.  One hypothesis has suggested that these epidemiologic changes are related to a changing microbiome.  This in turn may be related to frequent antibiotic usage.  An example of the proliferation of antibiotics: “20-25% of Swedish adults receive an antibiotic prescription annually.”

While H pylori may be a biomarker associated with poor hygiene/less antimicrobial exposure, it does not appear to be directly related to EoE.  The authors indicate that until we have a better understanding, “in the meantime attention to healthier diets and minimizing antibiotic exposure may optimize public health in terms of atopic disease risk.”

My take: Since our genetics do not change quickly, the dramatic changes in disease frequency of conditions like EoE and Crohn’s disease must be influenced by environmental exposures.  How to lower the risk of these conditions remains uncertain.

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Not a joke –WIFI hotspot at Sunshine Meadows, Banff National Park