The FDA provides a lot more information about the Adstiladrin trial than you can find through a Google Search. If you go to
FDA.gov and search for
Adstiladrin you get to this page of results:
https://www.fda.gov/search?s=Adstiladrin&sort_bef_combine=rel_DESC There is a link to a zip file that can be downloaded labelled -
Approval History, Letters, Reviews and Related Documents - ADSTILADRIN This zip file contains 15 pdf documents - one of which is named
Clinical Review Memo - ADSTILADRIN.pdf. This document contains a wealth of information about the Adstiladrin trial, including this chart on page 61 which shows that the duration of CR drops rapidly after 12 months (which is defined here as 12 months after the initial CR at 3 months).
Table 12: rAD-IFN-CS-003 Summary of Response Duration Among 103 Patients with BCG-Unresponsive CIS-Containing NMIBC per FDA Guidance: DCO 15-November 2019
(FDA Table) | Endpoint | CIS Cohort |
| Complete Response, n (%) [95% CI] | 55 (53.4%; 95% CI 43, 63%) |
| Duration of Response | |
| Median in months (range) | 9.69 (3.0+, 31.1+) |
| Duration >/= 6 months | 38 (36.9%) |
| Duration >/= 12 months | 24 (23.3%) |
| Duration >/= 18 months | 13 (12.6%) |
| Duration >/= 24 months | 4 (3.9%) |
At 18 months past the initial CR, Adstiladrin's CRR has dropped to 13% and 6 months after that it is down to 4%.!
The follow- up of responders after 12 months was baked in to the Adstiladrin trial but it was never explicitly part of the Ruvidar trial.
I think this may have been an oversight. The FDA approved Adstiladrin in December 2022 because of safety and a 15 month CRR of 23%.
The FDA is now considering the case for the approval of Ruvidar PDT. Safety is clearly good and at 33% CR at 15 months (so far) efficacy is much better than Adstiladrin.
It would be only natural for the FDA to want to know if the efficacy of Ruvidar at 15 months drops off as quickly as does that of Adstiladrin just so they can fairly compare the 2 treatments. They probably asked for those numbers and Theralase replied with some version of - "
we'll get back to you". They then scrambled to change the protocol and get approval from HC to make this followup a part of the trial.
IMHO long term duration of CR of Ruvidar PDT will be incomparably better than Adstiladrin.
When they see the long term response numbers of Ruvidar IMHO the FDA will quickly grant accelerated approval.