Feasibility of a Lifestyle Intervention for Women With Triple-negative Breast Cancer Under Neoadjuvant Immunotherapy

Feasibility of a Lifestyle Intervention to Switch to a High-fiber, Gut-healthy Diet in Women With Triple-negative Breast Cancer Undergoing Neoadjuvant Immunotherapy: a Randomized Controlled Trial

Triple-negative breast cancer (TNBC) is considered a tumor with a high risk of recurrence and metastasis and requires aggressive systemic therapy combining immunotherapy and chemotherapy. If the therapy leads to complete remission (pCR), this is prognostically beneficial for patients.

Studies demonstrating the influence of the microbiome on the development of cancer and on the efficacy and toxicity of immunotherapy and chemotherapy underscore the potential of targeted nutritional interventions. Current data from microbiome research indicate that a high-fiber, gut-healthy diet modulates the microbiota in such a way that the response to and toxicity of immunotherapy and chemotherapy could be improved.

The aim of this project is to translate these findings into clinical care. The study will investigate whether an online integrative oncology group training program with mind-body elements supports and is feasible for the implementation of a high-fiber diet in patients with TNBC undergoing neoadjuvant immunotherapy and chemotherapy. The program will be compared with a control group that receives a flyer with nutritional recommendations. If the feasibility of this complementary medicine approach can be demonstrated, a confirmatory study is planned to investigate the expected effect on the pathological complete remission of TNBC.

This study examines a nutritional concept developed specifically for this study with regard to the implementation of a switch to a high-fibre diet in patients with TNBC undergoing neoadjuvant immunotherapy and chemotherapy. This nutritional concept is embedded in an online, integrative oncology group training programme with mind-body medicine elements to support the change in diet and its tolerability. This intervention is compared with a control group that receives standard care, i.e. a flyer and an educational training video with nutritional recommendations based on the guidelines of the German Nutrition Society (DGE).

The following criteria have been established to determine the feasibility of these two target levels:

• Recruitment
• Consent to participate and randomisation
• Dropout rate
• Implementation of the intervention (dietary change and acceptance/effect of mind-body elements)
• Completeness of data collected for at least 80% of patients who complete the study

If the study proves feasible and demonstrates the viability of this integrative medical approach in women with TNBC undergoing neoadjuvant immunotherapy, a confirmatory intervention study with a larger sample size is planned. This study aims to contribute to expanding the current knowledge base and improving existing treatment options. The follow-up study aims to investigate the effects of the nutritional concept and the group training programme on the pCR of TNBC. It will analyse whether the nutritional concept and the group training programme enhance the response to immunotherapy and improve its tolerability in the study participants. The findings from this study will therefore be incorporated into the follow-up study, which will investigate the potential for an improved immune response to therapy and, at the same time, identify possible positive effects of the nutritional intervention on the side effect profile of immunotherapy. Furthermore, the design of the nutritional concept and/or the group training programme could be adapted for the follow-up study if the results are appropriate. The findings from both studies will then be transferred to clinical care, thereby optimising the current treatment options for TNBC patients and increasing their chances of recovery in the long term.

Inclusion Criteria:

• Female patients aged 18-75
• Histologically confirmed diagnosis of non-metastatic triple-negative breast cancer (TNM stage I-III) with planned neoadjuvant chemotherapy and immunotherapy
• Willingness to participate in the study and signed consent form

Exclusion Criteria:

• Advanced stage of disease with metastases
• Severe physical or psychopharmacologically treated psychiatric comorbidity that prevents a patient from participating in the study
• Pregnancy
• Participation in other clinical studies involving behavioral, psychological, or complementary medical interventions
• A diet that is incompatible with a high-fiber diet, such as the ketogenic diet
• Abuse of drugs and/or alcohol
• Inability to complete the questionnaires independently
• Colectomy
• Gastrointestinal stenosis
• Fructose intolerance
• Histamine intolerance
• Gluten intolerance
• Ketogenic diet
• Unwillingness to refrain from taking probiotics for the duration of the study
• Eating disorders
• No laptop and/or camera available to participate in the online group training program