similarly. Demographic and baseline disease characteristics, as
well as adverse events, were descriptively summarized.
The sample size was calculated as the following: based on the results from the Phase IIb study,24 the treatment difference between the once-daily treatment of BT gel 0.5% and vehicle gel in the average success rate across all time points was 19.9%, 17.6%, and 22.9% for days 1, 15, and 29, respectively. Considering the variability and vehicle effect may be higher in the present Phase III studies, it was assumed that the treatment difference in success rate between the active and controlled groups was 15%, the correlation between repeated measurements was 0.7, and the dropout rate was 10%. A sample size of 260 with 130 subjects per arm was hereinafter estimated to be sufficient to detect the specified treatment difference of 15% in success rate with a statistical power of 90% when conducted as a two-sided test at the 5% significance level.
RESULTS
The two studies were carried out from May, 2011 to Sept, 2011, and
from May 2011 to Nov, 2011, respectively. The periods of recruitment
were May, 2011 to July, 2011 and May 2011 to Sept, 2011.
Disposition, Demography, and Baseline Characteristics
The two studies were very similar in terms of study disposition,
demography, and baseline characteristics.
In both studies, the vast majority of subjects reported normal
study completion, with similarly low number of subject discontinuations
in the two groups. A total of 260 subjects were
enrolled into study A and 254 (97.7%) completed it normally
(Figure 1). Among the 293 subjects enrolled into study B, 283
(96.6%) reported normal study completion.
The groups of BT gel 0.5% and vehicle gel were comparable
in terms of demographic characteristics in both studies (Table
1.). The majority of subjects were female (79.2% and 72.7% in
studies A and B, respectively) and Caucasian/White (98.5% and
98.6%, respectively). Most subjects had a Fitzpatrick skin phototype
of II (53.5% and 58.7%, respectively), and the mean age
was 48.8 year in study A and 47.5 year in study B. At baseline,
the groups of BT gel 0.5% and vehicle gel also had similar severity
of erythema in both studies, with the majority of subjects
having moderate erythema based on either CEA or PSA.
Efficacy
The results of efficacy analyses were similar between the two studies,
with significantly greater efficacy demonstrated for BT gel 0.5%
compared with vehicle gel on all efficacy variables in each study.
The primary endpoint of both studies was the profile of success,
defined as 2-grade improvement on both CEA and PSA over 12
hours. Significantly greater success was achieved with BT gel 0.5%
