LS301-IT in Partial Mastectomy and Sentinel Lymph Node Biopsy (SLNB) for DCIS or Stage I-II Primary Invasive Breast Cancer

This is a Phase 1b/Phase 2, open-label study to investigate the use of LS301-IT (investigational medicinal product \[IMP\]), a fluorescence imaging agent used for visualization of tumor margins and SLNs in female patients with DCIS or Stage I-II, primary invasive carcinoma of the breast, for which the patient's primary surgical treatment is partial mastectomy. Eligible patients will be enrolled into either: * Phase 1b (Period 1): dose finding (escalation/de-escalation), and dose timing adjustment; * Phase 2a (Period 2): expanded sample size based on acceptable dosing regimen, that being the dose level(s) and time interval between LS301-IT injection and surgery, determined in Period 1; or * Period 2b (Period 3): allow surgeon to make additional surgical decisions based on fluorescence imaging findings during surgery (Period 3 will not be opened until results are available from Periods 1 and 2 and further FDA consultation is obtained).