Table 4.

Ongoing interventional studies evaluating the role of metformin in breast cancer treatment (by 25 January 2022).

Study Designation	Phase	N	Clinical Setting	Study Medication	End Point
NCT04559308 (Recruiting)	II	80	Neoadjuvancy	4 cycles of EC followed by weekly paclitaxel plus metformin (1000 mg bis)/control	Clinical benefit rate (tumor size)
NCT04387630 (Recruiting)	II/III	120	Neoadjuvancy	Neoadjuvant treatment as physician’s choice plus metformin (from 850 mg–2550 mg/day)/pbo	Clinical response rate T-cell cytotoxic markers
NCT01589367 (Completed)	II	208	Neoadjuvancy	Letrozole plus metformin (1000 mg bis)/pbo up to 24 weeks prior to surgery	Clinical response rate
NCT01929811 (Active, not recruiting)	II	92	Neoadjuvancy	TEC plus metformin(500 mg/day)/control	pCR
NCT04248998 (Recruiting)	II	90	Neoadjuvancy in TN breast cancer	4 cycles of AC followed by weekly paclitaxel + FMD +metformin (850 mg bis)/pbo	pCR
NCT02488564 (Completed)	II	49	Neoadjuvancy in HER-2 positive breast cancer	Liposomal doxorubicin in combination with Docetaxel and Trastuzumab plus Metformin (1000 mg bis)	pCR
NCT05023967 (Recruiting)	II	120	Localized BC not tributary to neoadjuvant treatment	Fast for ≥16 h plus metformin (1500 mg/day) vs. observation for 4–6 weeks prior to surgery	Ki67 levels Incidence of adjacent DCIS Toxicity
NCT04143282 (Completed)	II	250	Metastatic breast cancer	Standard chemotherapy plus metformin (1000 mg bis)	Radiologic response rate OS, DFS

Note: bid; bis in die, pbo, placebo; FMD, Fasting Mimicking Diet; AC, Adriamycin- Cyclophosphamide; EC, Epirubicin—Cyclophosphamide; TEC; Docetaxel, Epirubicin, Cyclophosphamide; pCR, pathologic complete response; OS, overall survival; DFS, disease free survival; DCIS, Ductal carcinoma in situ.