>> but are you saying that this dosing issue will undermine the MEDI-507 trials for psoriasis? <<
That's sort of strong wording, but...... maybe.
507 has been demonstrated, in two in vitro studies, to have a unique action..... it eliminates only activated T cells. For this reason, I've always been interested in low dose application, where generalized T cell depletion would not be observed.
Read the MEDI release. They clearly state that efficacy in the phase II subcutaneous trial was correlated with T cell depletion.
This is flat out not true for the i.v. trial, and it's results from that trial that interested me most. Yes, efficacy was ass'd with depletion in the subcutaneous trial. And, yes, at this late stage in the game, MEDI needs to make a choice with respect to route and dose and get on with it.
However...... those who have seen the data will agree with me, 100%. There was no dose response apparent from the i.v. trial; the lowest, non-depleting dose was just as effective as higher doses. The trial was not sufficiently powered to draw conclusions, however, and it ticks me off that we've go on FOREVER and still don't have sufficient data regarding repeat dosing at non-depleting concentrations. MEDI has screwed up (and delayed, IMO) the testing of 507 from onset.
If i were a MEDI shareholder, I'd demand that they re-report the phase I/II data, that they take the spin off of the i.v. results.
Re. RA........ MEDI mentioned, consistently for a couple of months, that a phase II trial for RA would begin this year. Maybe that's still the case, but..... since they started to talk about RA in the context of Vitaxin, I get the feeling that they're backing off of their strong RA stance re. 507. I hope that it's just my imagination.
MEDI has turned out to be, IMO, one very lousy partner. Sure wish that we could buy back rights to the molecule. An indication of efficacy at 0.0012 mg/kg!!
MedImmune has a comprehensive Phase II development program underway with siplizumab. Currently, the company has three
active Phase II trials: a randomized, double-blind, placebo-controlled, subcutaneous administration trial involving 400 patients
at approximately 50 sites in North America (enrollment ongoing); a randomized, double-blind, placebo-controlled, intravenous
administration trial involving 124 patients at approximately 25 sites in North America (dosing complete); and a randomized,
double-blind, subcutaneous administration trial involving 121 patients at approximately 20 sites in Europe (enrollment
complete).
These trials should give us a clearer picture of how to use the antibody. If it is used at depleting concentrations, the magic, for me, will be gone. |
