Given that we have a fair degree of information about the wound healing rates of the blinded data, it's critical to build an expectation of how the control arm is likely to perform in order to gauge the likelihood of sucess of FTT's current trial (VF00102).
I spent some time over the weekend reading completed VLU trial papers trying to find a trial with similar inclusion and screening parameters to FTT's VF00102 trial. After combing through a stack of trials, I found MiMedx's 2017 write up of a controlled (but not double blinded) trial of their EpiFix (Dehydrated Human Amnion/ Chorion Membrane) product which is currently approved for DFU (and is a potential competitor to VF001 in VLU's). For those interested, the clinicaltrial.gov ID is NCT02011503; and the investigation write up has been published in The International Wound Journal (
Volume15, Issue1 February 2018 Pages 114-122,
https://onlinelibrary.wiley.com/doi/full/10.1111/iwj.12843)
Like VF00102, the EpiFix VLU trial is a US multi-centre trial with a similar profile of recruitment centres. And while the enrolment criteria for the EpiFix trial are a little different to VF00102 (e.g. VLU duration > 30 days; VLU base-area of < 25 mm^2), importantly, the trial DID include a 2 weeks screening phase that ejected patients who had a reduction in VLU base-area of > 25 mm^2). This is the only trial I can find that that included a two week screen to weed out self healers.
The 12-week control-arm data from the EpiFix trial was as follows:
- Mean Reduction in VLU Base-Area: 40% (versus 66% in the active arm);
- Probability of healing: 35% (versus 60% in the active arm).
Also worth noting is that the average VLU base-area of enrolled patients in the EpiFix trial was significantly smaller than than the 25mm max (7.6 mm and 8.33 mm receptively in control and treatment arm).
Based on this, and acknowledging that the EpiFix trial did-not pre-screen on Margolis score, I have notched my confidence up a notch that VF00102 is likely to have genuinely enrolled relatively difficult healers meaning that the healing curves presented by the company to date probably represent decent activity of VF001 in the active arms (2/3 of the blinded pool).
(20min delay)