P70: Real‐world effectiveness of guselkumab in achieving absolute PASI thresholds and mean DLQI scores in patients with moderate‐to‐severe plaque psoriasis: analysis of the BADBIR registry following 6 months of treatment

Abstract

paired serum samples from 40 patients. A therapeutic range of 3 9–7 9 lg L was estimated using Passing–Bablok regression. Next, we developed a TDM protocol based on current evidence and expert consensus opinion. The protocol comprises both proactive (weeks 4 and 16 of treatment, and annually thereafter) and reactive (at clinical evidence of loss of response) TDM. Reflex antidrug antibody testing occurs if adalimumab levels are < 5 lg L. Following the training of local clinicians, the protocol was implemented in all individuals receiving adalimumab who presented for routine review from 1 December 2020. Serum adalimumab level measurement was adopted as a key performance indicator in our local management pathway. We evaluated operational viability and clinical utility of the TDM protocol. To date, 21 patients with psoriasis have been managed according to the TDM protocol: 10 (48%) female, 17 (81%) of white European ethnicity, nine (43%) never smokers and seven (33%) with concurrent psoriatic arthropathy. Median age was 47 years [interquartile range (IQR) 41–51], body mass index 30 8 kg m (IQR 26 6– 33 7) and duration of psoriasis 25 5 years (IQR 19 3–32 8). Adalimumab was administered weekly in three (14%) patients, fortnightly in 17 (81%) and every 3 weeks in one (4 8%). The median duration of adalimumab therapy was 32 months (IQR 13–50). Median serum adalimumab was 5 3 lg L (IQR 4 1–6 9); levels were within the therapeutic range in 10 (48%) patients, subtherapeutic in seven (33%) and supratherapeutic in four (19%). TDM influenced clinical decisions in five (24%) patients. TDM prompted treatment escalation or switch in three patients with loss of response. Owing to the risk of relapse, two patients with stable disease but subtherapeutic adalimumab and detectable antidrug antibody were scheduled for expedited follow-up to discuss treatment switch. These data indicate the clinical viability of adalimumab TDM and its potential use in informing clinical decision-making in routine psoriasis care. Larger-scale, longer-term followup data will help characterize the impact of routine TDM on clinical outcomes.