RE: Is this the whole story2 Jun 2023 14:52
@RD " I don't think it's possible to give ava6000 at doses that create systemic concentrations similar to normal dox - surely that's the benchmark in terms of tolerance."
When it comes to toxicity, I think it may not be about systemic concentrations at any particular time point rather than about the total systemic dose in each cycle.
Put another way, conventional doxirubicn is given as a bolus intravenous infusion which immediately circulates in the blood and diffuses into and out of tissues, killing cells that are dividing, until it is all excreted after a short time (as some have said it has a very short half-life in the circulatory system). Thus there is a high initial concentration that falls off sharply. Whereas the AVA6000 bolus infusion circulates until taken up and retained in tissue containing FAP (diffusing into and out of all other tissue types) or is excreted. The only doxurubicin in the circulatory system is therefore the cleaved product of AVA6000 from FAP-containing tissue. This 'slow release' of doxorubicin into the blood stream is fundamentally different from the bolus infusion of conventional doxorubicin - I would expect the former to show a an extended bell curve and the latter a, relatively-speaking, blip: a gentle pummeling vs a knockout punch.
Thus peak concentration (biggest punch) and area under the curve (aggregated strength of punch/es) are the true measures of potential toxicity.
My thoughts. But I've never fully understood and am certainly no expert in PK, toxicoloy or oncology!