SIB in Studies of Brodalumab
In addition to assessing the effect of brodalumab treatment on symptoms of depression and anxiety in patients with psoriasis, the brodalumab clinical trial program also tracked patterns of SIB among enrolled patients. In contrast with other clinical trials in which patients with a history of psychiatric disorders or substance abuse were excluded, clinical trials of brodalumab did not exclude patients with psychiatric disorders (eg, SIB, depression) and were therefore reflective of the real-world population of patients with moderate to severe psoriasis.22
In a recently published, detailed analysis of psychiatric adverse events (AEs) in the brodalumab clinical trials, data related to SIB in patients with moderate to severe psoriasis were analyzed from the placebo-controlled phases and open-label, long-term extensions of a placebo-controlled phase 2 clinical trial and from the previously mentioned 3 phase 3 clinical trials.22 From the initiation of the clinical trial program, AEs were monitored during all trials. In response to completed suicides during some studies, additional SIB evaluations were later added at the request of the US Food and Drug Administration, including the Columbia Suicide Severity Rating Scale, the PHQ-8, and the Columbia Classification Algorithm for Suicide Assessment, to independently adjudicate SIB events.22
In total, 4464 patients in the brodalumab clinical trials received at least 1 dose of brodalumab, and 4126 of these patients received at least 1 dose of brodalumab 210 mg Q2W.22 Total exposure was 9174 patient-years of brodalumab, and mean exposure was 23 months. During the 52-week controlled phases of the clinical trials, 7 patients receiving brodalumab experienced any form of SIB event, representing a time-adjusted incidence rate of 0.20 events (95% confidence interval [CI], 0.08-0.41 events) per 100 patient-years of exposure. During the same 52-week period, patients receiving the comparator drug ustekinumab had an SIB rate of 0.60 events (95% CI, 0.12-1.74 events) per 100 patient-years, which was numerically higher than the rate with brodalumab. Inferential statistical analyses were not performed, but overlapping 95% CIs around these point estimates imply a similar level of SIB risk associated with each agent in these studies. During controlled and uncontrolled treatment periods in all studies, the SIB rate among brodalumab-treated patients was 0.37 events per 100 patient-years.22
Over all study phases, 3 completed suicides and 1 case adjudicated as indeterminate by the Columbia Classification Algorithm for Suicide Assessment review board were reported.22 All occurred in men aged 39 to 59 years. Of 6 patients with an AE of suicide attempt, all patients had at least 1 SIB risk factor and 3 had a history of SIB. The rate of SIB events was greater in patients with a history of depression (1.42) or suicidality (3.21) compared to those without any history of depression or suicidality (0.21 and 0.20, respectively).22 An examination of the regions in which the brodalumab studies were conducted showed generally consistent SIB incidence rates: 0.52, 0.29, 0.77, and 0 events per 100 patient-years in North America, Europe, Australia, and Russia, respectively.24
As previously described, depression and other risk factors for SIB are prevalent among patients with psoriasis. In addition, the rate of suicide mortality has increased substantially over the last decade in the general population, particularly among middle-aged white men,29 who made up much of the brodalumab clinical trial population.22 Therefore, even without treatment, it would not be surprising that SIB events occurred during the brodalumab trials. Most patients with SIB events during the trials had a history of predisposing risk factors.22 Prescribing information for brodalumab in the United States includes a boxed warning advising physicians to be aware of the risk of SIB as well as a statement that a causal relationship between SIB and brodalumab treatment has not been established.27