Patients that experience PIGT after receiving first standard of care cycle of pertuzumab-based chemotherapy receive rifaximin PO BID on days 1-5 and standard of care pertuzumab-based chemotherapy on day 1. Treatment repeats every 21 days for up to 5 cycles in the absence of disease progression or unacceptable toxicity.

Patients that do not experience PIGT after receiving first standard of care cycle of pertuzumab-based chemotherapy continue receiving standard of care pertuzumab-based chemotherapy on day 1. Treatment repeats every 21 days for up to 5 cycles in the absence of disease progression or unacceptable toxicity.

Anatomic Stage I Breast Cancer AJCC v8

Anatomic Stage IA Breast Cancer AJCC v8

Anatomic Stage IB Breast Cancer AJCC v8

Anatomic Stage II Breast Cancer AJCC v8

Anatomic Stage IIA Breast Cancer AJCC v8

Anatomic Stage IIB Breast Cancer AJCC v8

Anatomic Stage III Breast Cancer AJCC v8

Anatomic Stage IIIA Breast Cancer AJCC v8

Anatomic Stage IIIB Breast Cancer AJCC v8

Anatomic Stage IIIC Breast Cancer AJCC v8

HER2 Positive Breast Carcinoma

Prognostic Stage I Breast Cancer AJCC v8

Prognostic Stage IA Breast Cancer AJCC v8

Prognostic Stage IB Breast Cancer AJCC v8

Prognostic Stage II Breast Cancer AJCC v8

Prognostic Stage IIA Breast Cancer AJCC v8

Prognostic Stage IIB Breast Cancer AJCC v8

Prognostic Stage III Breast Cancer AJCC v8

Prognostic Stage IIIA Breast Cancer AJCC v8

Prognostic Stage IIIB Breast Cancer AJCC v8

Prognostic Stage IIIC Breast Cancer AJCC v8

Given standard of care pertuzumab-based chemotherapy

Best Practice

Questionnaire Administration

Rifaximin

Mayo Clinic in Florida

Rifaximin for the Treatment of Gastrointestinal Toxicities Related to Pertuzumab-Based Therapy in Patients With Stage I-III HER2 Positive Breast Cancer

Phase II Trial of Rifaximin in Patients With Early Stage HER2 Positive Breast Cancer With Gastrointestinal Toxicities Related to Pertuzumab-Based Therapy

Based on the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE). The proportion of successes will be estimated by the number of successes divided by the total number of evaluable patients. Confidence intervals for the true success proportion will be calculated according to the approach of Duffy and Santner (1987).

Descriptive statistics (frequency table) and histogram will be used to summarize dose reductions of treatment with pertuzumab due to gastrointestinal side effects.

Descriptive statistics (frequency table) and histogram will be used to summarize dose delays of treatment with pertuzumab due to gastrointestinal side effects.

Descriptive statistics (frequency table) and histogram will be used to summarize discontinuation of treatment with pertuzumab due to gastrointestinal side effects.

Descriptive statistics (frequency table) and histogram will be used to summarize the Bristol stool scale during the study. Values range from 1 to 7 based on appearance. Outcome not based on value.

Descriptive statistics (frequency table) and histogram will be used to summarize other PIGT such as abdominal pain, bloating and flatulence as measured by a 4 point Likert scale during the study.

Descriptive statistics (mean, standard deviation [sd], median, interquartile range [iqr]) and longitudinal plots (raw value, change, change in percentage) will be used to summarize the baseline levels of hydrogen/methane peak by specific species by fecal microbiome before and after rifaximin.

Descriptive statistics (mean, sd, median, iqr) and longitudinal plots (raw value, change, change in percentage) will be used to summarize the baseline levels of hydrogen/methane peak by hydrogen breath test before and after pertuzumab-based chemotherapy.

Descriptive statistics (mean, sd, median, iqr) and longitudinal plots (raw value, change, change in percentage) will be used to the fecal microbiome test among patients with or without PIGT. The study is not powered to detect any differences between the two arms; the main purpose is to quantify and evaluate differences descriptively between patients who develop and do not develop PIGT (between arm 1 and arm 2) to inform subsequent research.

Descriptive statistics (mean, sd, median, iqr) and longitudinal plots (raw value, change, change in percentage) will be used to the hydrogen breath test among patients with or without PIGT. The study is not powered to detect any differences between the two arms; the main purpose is to quantify and evaluate differences descriptively between patients who develop and do not develop PIGT (between arm 1 and arm 2) to inform subsequent research.

Descriptive statistics (mean, sd, median, iqr) and longitudinal plots (raw value, change, change in percentage) will be used to the permeability test among patients with or without PIGT. The study is not powered to detect any differences between the two arms; the main purpose is to quantify and evaluate differences descriptively between patients who develop and do not develop PIGT (between arm 1 and arm 2) to inform subsequent research.

Mayo Clinic

National Cancer Institute (NCI)

Participants will take one 40 mg capsule of Pantoprazole daily for 5 days at the beginning of cycle 1 then they will take one capsule of matched Placebo daily for 5 days at the beginning of cycle 2

Participants will take one capsule of matched Placebo daily for 5 days at the beginning of cycle 1 then they will take one 40 mg capsule of Pantoprazole daily for 5 days at the beginning of cycle 2

Oncology

Breast Cancer

Chemotherapy-induced Nausea and Vomiting

Proton pump inhibitor, drug action is to irreversibly block the hydrogen-potassium adenosine triphosphatase enzyme system (the 'proton pump') of the gastric parietal cell. This reduces basal and stimulated gastric acid secretion therefore raising gastric pH.

Pantoprazole 40mg

Placebo

Cancer Trials New Zealand website study record

Breast Cancer Foundation website study record (Co-funder)

Pantoprazole Prophylaxis Against Delayed CINV for Patients Receiving Breast Cancer Chemotherapy

Phase II, Randomised, Double-blinded, Placebo Controlled, Crossover Trial to Assess Pantoprazole's Effectiveness as Prophylaxis Against Delayed CINV in Patients Receiving Adjuvant or Neoadjuvant Breast Cancer Chemotherapy

To determine whether Pantoprazole can reduce the incidence of delayed CINV in patients receiving adjuvant or neoadjuvant breast cancer chemotherapy (as measured on day 5 using the MASCC Antiemesis Tool (MAT) to assess nausea over days 2-5 of each chemotherapy cycle) as compared to placebo. Specifically, the primary endpoint will be the complete absence of both nausea and vomiting during days 2-5.

Whether Pantoprazole improves nausea MAT scores over days 2-5

Whether Pantoprazole reduces the number of episodes of vomiting (MAT) over days 2-5

Whether Pantoprazole improves heartburn score (measured using the FSSG for reflux and/or dyspepsia) as self-reported on day 5 regarding days 2-5.

Whether FSSG scores (heartburn) are associated with the MAT nausea scores reported by the patient over days 2-5.

Whether Pantoprazole lowers the requirement for breakthrough medications (as self-recorded by the patients on days 2-5).

Whether Pantoprazole is preferred by patients over Placebo (by using a patient preference survey at the end of cycle 2).

To assess whether adverse events (including hypomagnesemia, diarrhoea, abdominal pain and headache as defined by CT CAE version 4.03) are more common on Pantoprazole than on Placebo.

Whether the chosen chemotherapy regimen (FEC vs AC vs TC) has an impact on the benefits of Pantoprazole in terms of delayed CINV, (as measured on day 5 using the MASCC Antiemesis Tool (MAT) to assess nausea over days 2-5 of each chemotherapy cycle) as compared to placebo.

To determine whether there is a cycle effect with respect to the incidence of delayed CINV as measured with the MAT (as measured on day 5 using the MASCC Antiemesis Tool (MAT) to assess nausea over days 2-5 of each chemotherapy cycle).

Dr Richard Isaacs

Medical Oncologist

University of Auckland, New Zealand

Double-blinded, randomised, crossover trial, phase II, stratified by the chemotherapy regimen

dyspepsia/breast neoplasms

Rifaximin for the Treatment of Gastrointestinal Toxicities Related to Pertuzumab-Based Therapy in Patients With Stage I-III HER2 Positive Breast Cancer

Pantoprazole Prophylaxis Against Delayed CINV for Patients Receiving Breast Cancer Chemotherapy

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