I agree with you that dosing should be optimised for each...

I agree with you that dosing should be optimised for each patient, though I doubt the optimal therapeutic dose will be difficult to find using body surface area (BSA) for people with different cancer types. There has been quite a large range of Bisantrene dosing in patients with some interesting regimens. For example, the P3 breast cancer trial had many patients who received an average 17 courses of 320 mg/m2 (5,440 mg/m2 total), while another trial provided 430 mg/m2 as a single bolus. For comparison, the lifetime cumulative dose for Doxorubicin is 450-550 mg/m2. This basically highlights that Bisantrene isn't a very toxic molecule and because it has already been used in combination with a wide range of other drugs, there is a pretty significant decrease in risk dosing it with Dox.

I imagine the dose escalation will consist of two parts and as such be quite simple. The introductory dose will be to determine that the combination is safe in humans, then the escalation will be to the established historical maximally tolerated (220 mg/m2) or to the maximum dose governed by ethics. If by optimal dose you meant optimal regimen (dose + days), then I still think the process will be fairly straight forward. Possibly, the more influential factor on dose and dose regimen will be the relationship between anti-cancer and cardiovascular effects.