In the first trial (VOYAGE 1) 329 patients were randomised to receive guselkumab, 334 adalimumab and 174 placebo. After 16 weeks of treatment with guselkumab the psoriasis had cleared or was minimal in 85.1% of the patients and 73.3% had achieved at least a 90% reduction in the PASI score (PASI 90). The corresponding figures were significantly lower for adalimumab (65.9% and 49.7%) and placebo (6.9% and 2.9%). Patients in the placebo group were then switched to guselkumab and by 48 weeks they had achieved similar responses to those seen in patients who took guselkumab for the whole trial. The advantage over adalimumab was also maintained at 48 weeks.1
The second trial (VOYAGE 2) had a similar design with 496 patients randomised to guselkumab, 248 to adalimumab and 248 to placebo, switching to guselkumab after 16 weeks. In addition, at 28 weeks patients who responded to guselkumab were re-randomised to continue it or switch to placebo. Those switched to placebo could be re-treated if the psoriasis relapsed. After 16 weeks the psoriasis was minimal or had cleared in 84.1% of the guselkumab group, 67.7% of the adalimumab group and 8.5% of the placebo group. The respective results for PASI 90 were 70%, 46.8% and 2.4%. These responses were sustained in patients who continued taking guselkumab throughout the trial. For those switched to placebo it took about 15 weeks for the benefit (PASI 90) to be lost. At 48 weeks 36.8% of these patients still had a PASI 90 response compared with 88.6% of those who continued treatment with guselkumab.2
In VOYAGE 2, 112 patients who did not respond to adalimumab were switched to guselkumab at week 28. By week 48, 66% of these patients had achieved a PASI 90 response.2
Another trial (NAVIGATE) looked at patients who did not respond to ustekinumab. After 16 weeks of treatment with ustekinumab 133 patients with an inadequate response were randomised to continue ustekinumab while 135 switched to guselkumab. The end point of the trial was the number of visits at which the investigators assessed the psoriasis as cleared or minimal. Between 28 and 40 weeks this outcome had been achieved at a mean of 1.5 visits with guselkumab and 0.7 visits with ustekinumab. The proportions of patients with minimal or cleared psoriasis at week 52 were 36.3% with guselkumab and 17.3% with continued ustekinumab.3
Infections were the most frequent adverse events in the clinical trials.1-3 These were mainly upper respiratory tract infections. Injection-site reactions were also common. Some patients develop antibodies to guselkumab and serious hypersensitivity reactions have occurred. In view of the risk of reactivation, patients should be screened for tuberculosis before starting guselkumab. Live vaccines should not be used during treatment or for 12 weeks afterwards. Guselkumab has not been studied in human pregnancy or lactation. Whether guselkumab significantly increases the risk of malignancy is uncertain.
Biological therapies can be considered when a patient with moderate to severe plaque psoriasis requires systemic therapy or phototherapy. The trials show that guselkumab has greater efficacy than placebo and adalimumab.1,2 It can also be considered for patients who do not respond to ustekinumab.3 As the effects of guselkumab wear off after the drug is stopped, treatment may need to be continued for a longer duration than in the trials. This will require additional monitoring of its safety.