Fasting mimicking diet as an adjunct toneoadjuvant chemotherapy for breast cancer in the multicentre randomized phase 2 DIRECT trial

Short-term fasting protects tumor-bearing mice against the toxic effects of chemotherapy while enhancing therapeutic efficacy. We randomized 131 patients with HER2-negative stage II/III breast cancer, without diabetes and a BMI over 18kgm(-2), to receive either a fasting mimicking diet (FMD) or their regular diet for 3 days prior to and during neoadjuvant chemotherapy. Here we show that there was no difference in toxicity between both groups, despite the fact that dexamethasone was omitted in the FMD group. A radiologically complete or partial response occurs more often in patients using the FMD (OR 3.168, P=0.039). Moreover, per-protocol analysis reveals that the Miller&Payne 4/5 pathological response, indicating 90-100% tumor-cell loss, is more likely to occur in patients using the FMD (OR 4.109, P=0.016). Also, the FMD significantly curtails chemotherapy-induced DNA damage in T-lymphocytes. These positive findings encourage further exploration of the benefits of fasting/FMD in cancer therapy. Trial number: NCT02126449. Preclinical evidence suggests that a fasting mimicking diet (FMD) can make cancer cells more vulnerable to chemotherapy, while protecting normal cells. In this randomized phase II clinical trial of 131 patients with HER2 negative early stage breast cancer, the authors demonstrate that FMD is safe and enhances the effects of neoadjuvant chemotherapy on radiological and pathological tumor response.