A Dietary Supplement (Resistant Potato Starch) for Reducing Musculoskeletal Symptoms in Individuals Planning to Receive Aromatase Inhibitor Therapy, AIMSS-RPS Trial

• Starch, Potato (Drug): Given PO

Primary outcomes

• Proportion of patients who took at least 70% of resistant potato starch (RPS) doses per protocol [Up to 24 weeks]: Will be assessed using patient self-report. The study will be deemed feasible if at least 60% of patients take at least 70% of protocol-directed doses of RPS, as assessed on the treatment logs. Will be evaluated with a 95% confidence interval.

Secondary outcomes

• Incidence of adverse events [Up to 24 weeks]: Will evaluate the frequency and severity of adverse events possibly, probably, or definitely associated with RPS. Safety and tolerability will be assessed using descriptive analysis of adverse event data (adverse events possibly, probably, or definitely associated with RPS) as well as analysis of patient-reported outcomes common terminology criteria for adverse events measures.
• Relative abundance of Bifidobacteria [At baseline and 12 weeks]: Will be assessed from stool. Sequencing data will be analyzed using standard protocols to identify butyrate generators. The primary analysis will compare relative abundance of Bifidobacteria at 12 weeks versus baseline, using Wilcoxon signed-rank tests.
• Proportion of patients who discontinue initially prescribed aromatase inhibitor medication due to toxicity [Up to 24 weeks]: Data regarding persistence with initially prescribed AI therapy will be obtained from physician notes in the electronic medical record and from patient-self report about reasons for AI discontinuation. Will estimate the proportion of participants who remain on their initially prescribed AI medication at 6 months, and report this proportion with exact 95% binomial confidence intervals. This estimate will be descriptively compared to the 86% persistence rate observed in a historical cohort.

Sex: All, accepts healthy volunteers

Inclusion Criteria:

* Patient who is planning to start standard-of-care AI therapy and receive treatment for at least 24 weeks. Can be planning to take AI therapy for stage 0-3 breast cancer or because they are at high risk of developing breast cancer. Concurrent gonadotropin-releasing hormone antagonist (GnRHa) therapy, anti-osteoclast therapy, anti-HER2 therapy, ribociclib, and/or PARP inhibitor are permitted
* Average joint pain 0-6 on a 0-10 scale during the 7 days prior to study enrollment
* Able to take oral medication
* Able to read and understand English
* Aware of the nature of her diagnosis, understands study requirement, and able to sign an informed consent form

Exclusion Criteria:

* Distant metastatic breast cancer
* Current or planned use of abemaciclib during study participation
* Current or planned use of chemotherapy or immunotherapy during study participation
* Pregnant or breast feeding, or planning to become pregnant during study participation
* Known active inflammatory bowel disease
* History of colectomy and/or gastric bypass
* Prior AI therapy except in the context of fertility treatment
* Planned use of prebiotics during study participation
* Use of estrogen supplementation other than vaginal estrogen
* Receipt of another investigational agent concurrent with participation in this trial

• Norah L Henry, M.D., Principal investigator, University of Michigan Rogel Cancer Center