What is the upper limits of anthracycline dose you are willing to give in a treatment-refractory metastatic breast cancer patient if the patient is responding to salvage weekly adriamycin after progression on multiple prior regimens?

I would not normally exceed 350-400 mg/m2. However, this is a tough situation in that the patient is treatment-refractory without many other great options and responding. According to the package insert, "the probability of developing impaired myocardial function based on a combined index of signs, ...