RE: Comparing dox and ava6k in the blood21 Aug 2023 11:41
great post jt, well argued. there are a couple of points though that i think could do with further discussion.
the data presented at science day was very sp**** and didn't show a clear dose/response trend. the margin for error is consequently very large. however i don't see how you got to ~16ng/ml for c6.
here are my workings for various scenarios, all assuming a linear dose/response:
taking the 4.9ng/ml of c1 (80mg/m²) as the base,
c6 (310mg/m²) = 4.9x(310/80) = 18.99ng/ml
taking the highest concentration, being 15.9ng/ml of c4 (200mg/m²),
c6 (310mg/m²) = 15.9x(310/200) = 24.65ng/ml
and for a c7 at the maximum allowed dosage,
c7 (400mg/m²) = 15.9x(400/200) = 31.90ng/ml
the last one is above the ~25ng/ml for the 50mg/m² dose, but the equivalent for 75mg/m² of doxorubicin would be ~37.5ng/ml, so in conclusion...
all calculations (being done on a linear dose/response) show free doxorubicin from ava6000 at 24 hours to be well below the normal level of naked doxorubicin doses at 24 hours based on calculations using the science day data and the report of ~25ng/ml doxorubicin in plasma from a 50mg/m² dose.
the second part of your argument, concerning the prevalence of side effects, is also well made. it is indeed a complex issue and we lack the important auc findings. i believe the difference between naked doxorubicin and the way doxorubicin is cleaved off ava6000 is important. the former is available in the plasma immediately, the latter only when ava6000 has found and been cleaved by fap. we don't know how much of the doxorubicin in the plasma never saw a tme (cleaved by fap outside a tme) and how much has leaked out from a tme. the single time point means that we also don't know the shape of the auc for doxorubicin from ava6000, nor how it differs from the shape of the auc for naked doxorubicin. the clinicians might know these already but the reliable and objective data we do have to go on are the reduced incidences and grades of doxorubicin side effects, so that's all good as well since, if the occurence of side effects is related to the auc, this means that the doxorubicin is very largely, massively even, being used up in the tme and... leads to progression free survival and potentially also tumour regression.