Probiotics for Prevention of Neratinib-Induced Diarrhea in Breast Cancer Patients

Participants in this group will receive a daily dose of probiotics as an adjunct to standard Neratinib therapy. The probiotics will be administered orally as a granule formulation dissolved in water, for a total duration of 6 weeks (two treatment cycles). Loperamide will be administered prophylactically according to the FDA-recommended schedule to prevent Neratinib-associated diarrhea. The aim is to assess the efficacy of probiotics in reducing Neratinib-induced diarrhea and improving quality of life.

Participants in this group will receive a daily dose of a placebo that is identical in appearance, taste, and administration method to the probiotic granules, in addition to standard Neratinib therapy. The placebo will be administered orally as a granule formulation dissolved in water, for a total duration of 6 weeks. Loperamide will also be administered prophylactically to all participants in accordance with FDA recommendations. This group will serve as a control to evaluate the true effect of probiotics on Neratinib-induced diarrhea.

All participants will receive prophylactic loperamide to reduce the risk of Neratinib-induced diarrhea. Loperamide will be administered according to the FDA-recommended schedule: 4 mg TID for the first 14 days of treatment, then 4 mg BID from Day 15 to Day 42. This intervention is implemented as a standard supportive therapy and not as a randomized variable.