Avid Bioservices Inc (CDMO)

[freethemice]

I really don't know what the argument is about. A bunch of people who have no idea what they are talking about.
Having the ability of measuring how much of the antibody is in the blood at a known time after administering the drug
is basic. As is the ability of measuring the concentration of antibody in a vial containing the antibody and saline.
These are basic things that are done all the time. In this paper, that I referred to before, the concentrations of
bavituximab are shown at different times after a dose was injected. As you can see in the table and figure doses of
1.0 mg/kg and 3 mg/kg are shown and easily distinguished. In the figure the serum concentrations are on a log scale.
As for the 18 samples measured controversy. I believe they were just repeating the PK measurements to
check the original results using 6 patients from each of the three trial arms. There is nothing more to say.

The paper which shows the pharmacokinetics of bavituximab is freely available to anyone here:
http://clincancerres.aacrjournals.org/content/17/21/6888.long
Phase I safety and pharmacokinetic study of bavituximab, a chimeric phosphatidylserine-targeting monoclonal antibody, in patients with advanced solid tumors.
Gerber DE, Stopeck AT, Wong L, Rosen LS, Thorpe PE, Shan JS, Ibrahim NK.
Clin Cancer Res. 2011 Nov 1;17(21):6888-96. doi: 10.1158/1078-0432.CCR-11-1074. Epub 2011 Oct 11.

Patients and Methods
Pharmacokinetics
From patients in the 0.1 and 0.3 mg/kg dose cohorts, pharmacokinetic samples were collected prestudy and on days 0, 1, 2, 4 ± 1, 7, 10, 14, and every 7 days from days 21 to 70. From patients in the 1 and 3 mg/kg dose cohorts, pharmacokinetic samples were collected prestudy and on days 0, 1, 2, 4 ± 1, 7, 14, 21, 22, 23, 25 ± 1, and every 7 days from days 28 to 56.

Bavituximab blood levels were determined by a validated ELISA. Noncompartmental pharmacokinetic analyses were conducted on individual serum bavituximab concentration–time data with WinNonlin Professional (version 5.2; Pharsight Corporation).

Results
Pharmacokinetics
Bavituximab exhibited linear single-dose (day 0, for all cohorts) and multiple-dose (for the 1 and 3 mg/kg cohorts on day 21; there was insufficient data for the 0.1 and 0.3 mg/kg cohorts on day 42) pharmacokinetic characteristics (Table 4 and Fig. 1). Following time to peak concentration (Tmax), mean serum bavituximab concentrations seemed to decline generally in an apparent monoexponential manner. Mean serum bavituximab concentrations on days 0 and 21 within dose groups were similar. Specifically, there were no significant differences in Tmax (P = 0.88), area under the plasma concentration-time curve from time zero to time t (AUCT; P = 0.96), AUCinf (day 1) versus AUCtau (day 21; P = 0.37), half-life [the time required to reduce the plasma concentration to one half its initial value (t1/2); P = 0.22], mean residence time [the average total time molecules of a given dose spend in the body (MRT); P = 0.68], apparent volume of distribution at steady state (Vz; P = 0.07), apparent volume of distribution during terminal phase (Vss; P = 0.16), clearance [the volume of plasma in the vascular compartment cleared of drug per unit time by the processes of metabolism and excretion (CL); P = 0.94], or AUCinf/dose (day 1) versus AUCtau/dose (day 21; P = 0.37). Mean half-life estimates ranged 37 to 44 hours on day 0 and 46 to 47 hours on day 21. With the 1 mg/kg dose, bavituximab concentration remained above 2 µg/mL (the predicted therapeutic threshold based on preclinical modeling) for 6 days. With the 3 mg/kg dose, bavituximab concentration remained above 2 µg/mL for 7 days.