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CONFERENCE CALL RE SILCAAT TERMINATION, November 1, 2002
CONFERENCE CALL RE SILCAAT TERMINATION, November 1, 2002
Notes by Bob Munk
Hi all,
There was a teleconference on Friday with Chiron to discuss their decision to terminate the SILCAAT trial. Several community folks were on the call, in addition to the CEO of Chiron and a few people from the IL-2 program, plus Cliff Lane from the NIH, a member of the SILCAAT Scientific Committee.
The discussion from Chiron's side reiterated that the decision was a business one. Through some very meandering and contradictory statements, we finally arrived at the following conclusions:
* The study IS "on track" in terms of critical assumptions, including enrollment and the overall number of clinical events being seen. Initially, the low number of events led to an increase in sample size to 2000, and extension of the study to 2007. The study is on track in terms of these revised parameters.
* Chiron has been looking at unblinded data relating to the secondary endpoint of viral load. (NOTE: The Scientific Committee has NOT looked at unblinded data.) This was part of their decision to terminate the study, given the projected costs of $20 million per year through 2007. However, results to date in enrollment and events are not worse than had been expected, although they might be characterized as being at the "low end" of expectations.
* Some of the patent protection held by Chiron for IL-2 will be expiring within the next several years. However, this picture is very confusing. IL-2 is apparently covered by numerous patents, including a "process patent" covering intermittent therapy held by NIH and licensed to Chiron. We did not get a clear picture of exactly what patient protection exists, and what will be lost, on what kind of timetable. Again, this was a factor in Chiron's decision.
* Community participants mentioned several concerns related to continuation of IL-2 access for study participants; the unprecedented decision to discontinue a study that is "on track" in terms of initial design assumptions; the negative impact on ever getting data to clarify the clinical benefits of IL-2; and the spin-off impact on any and all other immune-boosting therapies.
* Chiron will be meeting with the FDA to discuss the possibility of approval of IL-2 for use with "discordant responders" who have both a low viral load and low CD4 count. The community participants on the call were skeptical that this effort would be successful and noted the relatively small number of people in this category. In addition, since IL-2 is already approved for use in cancer therapy, it can already be used "off label" by any physician who wants to.
* The SILCAAT Scientific Committee is looking for a way to continue the study to its completion. They are in discussions with Chiron regarding a much-simplified data collection scheme and closer coordination with the ESPRIT trial of IL-2 for greater efficiency. They believe they can accomplish this for an annual cost of $5 million, and 4 more years of followup, or a total of $20 million compared to the current trial design costs of $20 million annually. One possible glitch in these discussions is that Chiron has not yet decided whether it would unblind the SILCAAT results to date, and said that it might do so if that would convince the FDA to grant the indication for discordant responders. This was received very negatively by the community participants as it would truly "pull the plug" on completion of the SILCAAT study to achieve its original goals.