Phase Ib/II Trial of coPANlisib in Combination With Trastuzumab in HER2-positive Breast Cancer. (Panther Study)

Phase Ib One of three dose levels of copanlisib is assigned at registration according to the dose escalation scheme. Phase II The copanlisib dose for the Phase II part of the trial will be based on the MTD established in the Phase Ib part of the study. Clinical and laboratory parameters will be assessed to evaluate disease response and toxicity of study therapy. Safety assessments will be performed throughout the study. Efficacy assessments (radiological examination) will be performed on all patients every 8 weeks for the first 24 weeks and every 12 weeks thereafter. Following baseline cardiac assessment, cardiac safety monitoring will include physical exam (with New York Heart Association (NYHA) functional classification for patients with diagnosed congestive heart failure) during each cycle, Multigated acquisition (MUGA) scan or Echocardiogram (ECHO) and 12 lead Electrocardiogram (ECG) within 7 days of Day 1 of every third cycle starting at cycle 3 (Cycle 3, Cycle 6, etc.).