Bimekizumab in patients with psoriatic arthritis, naive to biologic treatment: a randomised, double-blind, placebo-controlled, phase 3 trial (BE OPTIMAL).

BACKGROUND: Bimekizumab is a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17A and IL-17F. We assessed the efficacy and safety of bimekizumab in patients with active psoriatic arthritis who were naive to biologic disease-modifying antirheumatic drugs (DMARDs). METHODS: BE OPTIMAL was a 52-week, phase 3, multicentre, randomised, double-blind, placebo-controlled, active reference (adalimumab) trial done at 135 sites (hospitals, clinics, doctors' offices, and research centres) in 14 countries. Eligible patients were 18 years or older with a documented diagnosis of adult-onset psoriatic arthritis that met the Classification Criteria for Psoriatic Arthritis for at least 6 months before screening. Participants were randomly assigned with an interactive-voice and web-response system on the basis of a predetermined randomisation schedule (3:2:1, stratified by region and bone erosion number at baseline) to bimekizumab 160 mg every 4 weeks, placebo every 2 weeks, or the reference group (adalimumab 40 mg every 2 weeks), all administered subcutaneously. At week 16, patients randomly assigned to placebo switched to bimekizumab 160 mg every 4 weeks. The primary endpoint was the proportion of patients reaching 50% or greater improvement in American College of Rheumatology criteria (ACR50) at week 16 (non-responder imputation). Efficacy analyses included all patients who were randomly assigned (intention-to-treat population); the safety analysis set comprised patients who received one or more doses of treatment. Data are presented to week 24 (preplanned analysis). This trial is registered at ClinicalTrials.gov, NCT03895203. FINDINGS: Between April 3, 2019, and Oct 25, 2021, 1163 patients were screened and 852 were randomly assigned to bimekizumab (n=431), placebo (n=281), and reference (adalimumab; n=140) groups. At week 16, significantly more patients receiving bimekizumab (189 [44%] of 431) reached ACR50 response versus placebo (28 [10%] of 281; odds ratio 7·1 [95% CI 4·6-10·9], p<0·0001; adalimumab 64 [46%] of 140). All secondary hierarchical endpoints were met. Treatment-emergent adverse events up to week 16 were reported in 258 [60%] of 431 patients receiving bimekizumab, 139 [49%] of 281 patients receiving placebo, and 83 [59%] of 140 patients receiving adalimumab. No deaths occurred. INTERPRETATION: Bimekizumab treatment had superior improvements in joint, skin, and radiographic efficacy outcomes at week 16 compared with placebo in patients with psoriatic arthritis who were naive to biologic DMARDs. The safety profile of bimekizumab, including the occurrence of fungal infections, was consistent with previous phase 3 studies in patients with plaque psoriasis, and with IL-17A inhibitors. FUNDING: UCB Pharma.

Bimekizumab in patients with active psoriatic arthritis and previous inadequate response or intolerance to tumour necrosis factor-α inhibitors: a randomised, double-blind, placebo-controlled, phase 3 trial (BE COMPLETE).

BACKGROUND: Bimekizumab is a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F and IL-17A. This study compared the efficacy and safety of bimekizumab with placebo over 16 weeks in patients with active psoriatic arthritis and previous inadequate response or intolerance to tumour necrosis factor-α (TNFα) inhibitors. METHODS: BE COMPLETE was a phase 3, multicentre, randomised, double-blind, placebo-controlled trial conducted across 92 sites (including hospitals, clinics, and research centres) in 11 countries (Australia, Canada, Czech Republic, Germany, Hungary, Italy, Japan, Poland, Russia, the UK, and the USA). Eligible patients were aged 18 years or older with adult-onset psoriatic arthritis (meeting the Classification Criteria for Psoriatic Arthritis for at least 6 months before screening) with a history of inadequate response or intolerance to treatment with one or two TNFα inhibitors for either psoriatic arthritis or psoriasis. We stratified patients with active psoriatic arthritis by region and previous TNFα inhibitor use. Patients were randomly assigned (2:1) to receive subcutaneous bimekizumab 160 mg every 4 weeks or placebo by an interactive-voice and web-response system on the basis of a predetermined randomisation schedule. The primary endpoint was the proportion of patients with 50% or greater improvement in American College of Rheumatology criteria (ACR50) at week 16 (non-responder imputation). Efficacy analyses were done in the randomised population. The safety analysis set comprised patients who received one or more doses of study treatment. This trial was registered at ClinicalTrials.gov, NCT03896581, and is completed. FINDINGS: Between March 28, 2019, and Feb 14, 2022, 556 patients were screened and 400 patients were randomly assigned to bimekizumab 160 mg every 4 weeks (n=267) or placebo (n=133). The primary and all hierarchical secondary endpoints were met at week 16. 116 (43%) of 267 patients receiving bimekizumab reached ACR50, compared with nine (7%) of 133 patients receiving placebo (adjusted odds ratio [OR] 11·1 [95% CI 5·4-23·0], p<0·0001). 121 (69%) of 176 patients with psoriasis affecting at least 3% body surface area at baseline who received bimekizumab reached 90% or greater improvement in the Psoriasis Area and Severity Index (PASI90), compared with six (7%) of 88 patients who received placebo (adjusted OR 30·2 [12·4-73·9], p<0·0001). Treatment-emergent adverse events up to week 16 were reported in 108 (40%) of 267 patients receiving bimekizumab and 44 (33%) of 132 patients receiving placebo. There were no new safety signals and no deaths. INTERPRETATION: Bimekizumab treatment led to superior improvements in joint and skin efficacy outcomes at week 16 compared with placebo in patients with psoriatic arthritis and inadequate response or intolerance to TNFα inhibitors. The safety profile of bimekizumab was consistent with previous phase 3 studies in patients with plaque psoriasis, and studies of IL-17A inhibitors. FUNDING: UCB Pharma.

Effect of Bimekizumab on Patient-Reported Disease Impact in Patients with Psoriatic Arthritis: 1-Year Results from Two Phase 3 Studies.

OBJECTIVES: To evaluate 1-year bimekizumab efficacy in psoriatic arthritis (PsA) from the patient perspective using the 12-item PsA Impact of Disease (PsAID-12) questionnaire. METHODS: BE OPTIMAL (NCT03895203; biologic disease-modifying antirheumatic drug [bDMARD]-naïve), BE COMPLETE (NCT03896581; inadequate response/intolerance to tumour necrosis factor inhibitors [TNFi-IR]) and BE VITAL (NCT04009499; open-label extension) assessed bimekizumab 160 mg every 4 weeks in patients with PsA. Post hoc analyses of patient-reported disease impact, assessed by the PsAID-12 questionnaire, are reported to 1 year (collected to week 40 in BE COMPLETE). RESULTS: Overall, 1,112 total patients were included (698 bimekizumab, 414 placebo). Rapid improvements observed with bimekizumab treatment at week 4 continued to week 16 and were sustained to 1 year. At 1 year, mean (standard error) change from baseline in PsAID-12 total score was comparable between bimekizumab-randomized patients and patients who switched to bimekizumab at week 16 (bDMARD-naïve bimekizumab -2.3 [0.1], placebo/bimekizumab -2.2 [0.1]; TNFi-IR bimekizumab -|2.5 [0.1], placebo/bimekizumab -2.2 [0.2]). Proportions of bimekizumab-randomized patients achieving clinically meaningful within-patient improvement (≥3-point decrease from baseline) at week 16 were sustained to 1 year (bDMARD-naïve 49.0%; TNFi-IR 48.5%) and were similar for placebo/bimekizumab patients (bDMARD-naïve 44.4%; TNFi-IR 40.6%). Across studies and arms, 35.3% to 47.8% of patients had minimal or no symptom impact at 1 year. Improvements were observed to 1 year across all single-item domains, including pain, fatigue and skin problems. CONCLUSION: Bimekizumab treatment resulted in rapid and sustained clinically meaningful improvements in disease impact up to 1 year in bDMARD-naïve and TNFi-IR patients with PsA.

Bimekizumab treatment in biologic DMARD-naïve patients with active psoriatic arthritis: 52-week efficacy and safety results from the phase III, randomised, placebo-controlled, active reference BE OPTIMAL study.

OBJECTIVES: Bimekizumab (BKZ) is a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A. BKZ treatment has demonstrated superior efficacy versus placebo (PBO) at Week 16 in biologic disease-modifying antirheumatic drug (DMARD)-naïve patients with active psoriatic arthritis (PsA). Here, we report long-term efficacy and safety to Week 52. METHODS: BE OPTIMAL comprised a 16-week, double-blind, PBO-controlled period, then 36 weeks treatment-blind. Patients were randomised 3:2:1 to subcutaneous BKZ 160 mg every 4 weeks, PBO with switch to BKZ at Week 16, or reference arm (adalimumab (ADA) 40 mg every 2 weeks). Efficacy outcomes included the American College of Rheumatology (ACR) response criteria 20/50/70, Psoriasis Area and Severity Index (PASI) 75/90/100 in patients with baseline psoriasis affecting ≥3% body surface area and minimal disease activity (MDA); non-responder imputation. RESULTS: ACR20/50/70, PASI75/90/100 and MDA responses were sustained with BKZ to Week 52, consistent with results observed at Week 16. Patients who switched to BKZ at Week 16 demonstrated improvements in efficacy with similar results to BKZ-randomised patients by Week 52.To Week 52, 555/702 (79.1%) patients had ≥1 treatment-emergent adverse event (TEAE) during BKZ treatment; 113/140 (80.7%) on ADA. On BKZ, 46 (6.6%) patients had serious TEAEs. 54 (7.7%) Candida infections occurred during BKZ treatment and 1 (0.7%) during ADA; all cases were localised and non-serious. One death occurred in a BKZ-treated patient, unrelated to treatment. CONCLUSIONS: The efficacy of BKZ in bDMARD-naïve patients with PsA was sustained from Week 16 to Week 52. BKZ was well tolerated with no new safety signals observed. TRIAL REGISTRATION NUMBER: NCT03895203.

Effect of bimekizumab on symptoms and impact of disease in patients with psoriatic arthritis over 3 years: results from BE ACTIVE.

OBJECTIVES: Evaluate effects of long-term bimekizumab treatment on patient-reported outcome (PRO) measures, symptoms and the impact of PsA on patients. METHODS: Patients with active PsA were enrolled into BE ACTIVE, a 48-week randomised controlled trial (NCT02969525). After Week 48, patients could enter a 104-week open-label extension (NCT03347110), receiving bimekizumab 160 mg every four weeks. PRO measures assessed included arthritis pain visual analogue scale (VAS), PsA Impact of Disease (PsAID)-9, 36-Item Short Form Survey (SF-36) and HAQ-Disability Index (HAQ-DI). Results were analysed as mean (S.E.M.) changes from baseline (CfB) from Week 0 to the end of the open-label extension (3 years) and as percentage of patients reaching patient-acceptable symptom state (PASS) for global impact (PsAID-9 total score ≤4) and normal function (HAQ-DI total score <0.5). Non-responder imputation was applied to missing binary outcomes. RESULTS: In 206 patients (mean age 49.3 years, 51.0% male), completion rate was high; 161 (78.2%) patients completed Week 152. Bimekizumab treatment was associated with long-term sustained improvements in pain [arthritis pain VAS CfB; Week 48: -29.9 (1.9); Week 152: -32.0 (1.9)] and fatigue [PsAID-9 fatigue CfB; -2.4 (0.2); -2.7 (0.2)]. High percentages of patients achieved acceptable symptom state (PsAID-9 PASS: 75.2%; 65.0%) and normalised function (HAQ-DI <0.5: 49.0%; 46.1%). Improvements in patient global assessment and SF-36 Physical Component Summary were also sustained. CONCLUSIONS: Bimekizumab treatment was associated with long-term sustained improvements in pain and fatigue, reducing overall impact of PsA on patients. Physical function and quality of life improved up to 3 years. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT02969525, NCT03347110.

Bimekizumab in patients with active psoriatic arthritis: results from a 48-week, randomised, double-blind, placebo-controlled, dose-ranging phase 2b trial.

BACKGROUND: Dual neutralisation of interleukin 17A (IL17A) and interleukin 17F (IL17F) is a potential novel therapeutic approach in psoriatic arthritis. We assessed bimekizumab, a monoclonal antibody that selectively neutralises IL17A and IL17F, in patients with active psoriatic arthritis. METHODS: BE ACTIVE was a randomised, double-blind, placebo-controlled, dose-ranging phase 2b study done at 41 sites in the Czech Republic, Germany, Hungary, Poland, Russia, and the USA. Eligible patients aged 18 years or older with active adult-onset psoriatic arthritis and symptoms for at least 6 months were randomly assigned (1:1:1:1:1) to placebo, 16 mg bimekizumab, 160 mg bimekizumab, 160 mg bimekizumab with a one-off 320 mg loading dose, or 320 mg bimekizumab, which were administered as subcutaneous injections every 4 weeks for 12 weeks. After 12 weeks, patients assigned to the placebo and 16 mg bimekizumab groups were randomly reassigned (1:1) to either 160 mg or 320 mg bimekizumab, and all other patients remained on their originally assigned initial dose up to 48 weeks. Both participants and researchers were blinded to treatment allocation in the first 12 weeks, and blinded to the dose of bimekizumab thereafter. The primary endpoint was the proportion of patients with at least 50% improvement in the American College of Rheumatology response criteria at week 12, which was assessed in all patients who received at least one dose of study treatment and had a valid measurement of the primary efficacy endpoint at baseline. The trial, including all follow-up, has been completed. This trial is registered with ClinicalTrials.gov, NCT02969525. FINDINGS: Between Oct 27, 2016, and July 16, 2018, 308 patients were screened, and 206 were randomly assigned: 42 to the placebo group, and 41 each to the four bimekizumab groups. At 12 weeks, compared with the placebo group, significantly more patients in the 16 mg bimekizumab (odds ratio [OR] 4·2 [95% CI 1·1-15·2]; p=0·032), 160 mg bimekizumab (8·1 [2·3-28·7]; p=0·0012), and 160 mg (loading dose) bimekizumab (9·7 [2·7-34·3]; p=0·0004) groups achieved an ACR50 response. At 12 weeks, 24 (57%) of 42 patients in the placebo group and 68 (41%) of the 164 patients in the bimekizumab groups reported treatment-emergent adverse events. Most of these adverse events were mild or moderate. Serious treatment-emergent adverse events occurred in nine patients, eight of whom were receiving bimekizumab. No deaths or cases of inflammatory bowel disease were reported. INTERPRETATION: Bimekizumab doses of 16 mg and 160 mg (with or without a 320 mg loading dose) were associated with significant improvements in ACR50 compared with placebo, with an acceptable safety profile. Our results support phase 3 investigation of bimekizumab as a treatment for psoriatic arthritis. FUNDING: UCB Pharma.

Validity and score interpretation of the 12-item Psoriatic Arthritis Impact of Disease: an analysis of pooled data from two phase 3 trials of bimekizumab in patients with psoriatic arthritis.

OBJECTIVES: To investigate psychometric performance of the 12-item Psoriatic Arthritis Impact of Disease (PsAID-12) total and individual item scores in patients with psoriatic arthritis (PsA) and to estimate score change thresholds and scores corresponding to different levels of symptom/impact severity. METHODS: Data up to week 16 from 1252 patients with active PsA enrolled in two randomised controlled trials of bimekizumab (BE OPTIMAL (NCT03895203) and BE COMPLETE (NCT03896581)) were used to assess construct validity (correlations with other patient-reported outcomes), known-groups validity (based on Minimal Disease Activity index, Disease Activity Index for Psoriatic Arthritis and Psoriatic Arthritis Disease Activity Score), reliability (Cronbach's alpha and intraclass correlation coefficients (ICCs)) and responsiveness (sensitivity to change). Clinically meaningful within-patient improvement thresholds were estimated by anchor-based and distribution-based analyses, and symptom/impact severity thresholds were estimated by receiver operating characteristic curve analyses. RESULTS: The mean (SD) PsAID-12 total score at baseline was 4.19 (1.94). PsAID-12 scores demonstrated good convergent validity and good known-groups validity. Internal consistency reliability (Cronbach's alpha 0.95) and test-retest reliability (ICC ≥ 0.70) were also good. Responsiveness was acceptable (correlations ≥0.30 for most scores). Improvement thresholds were estimated at 1.5-2 points for the PsAID-12 total score and 2 or 3 points for item scores. Thresholds for different levels of symptom/impact severity could be derived for most PsAID-12 items. CONCLUSIONS: The PsAID-12 demonstrated robust psychometric properties in a large sample of patients with active PsA, supporting its use as a fit-for-purpose patient-reported outcome in this population. Furthermore, thresholds for score interpretation were derived.

Bimekizumab treatment in patients with active psoriatic arthritis and prior inadequate response to tumour necrosis factor inhibitors: 52-week safety and efficacy from the phase III BE COMPLETE study and its open-label extension BE VITAL.

OBJECTIVES: To assess 52-week safety and efficacy of bimekizumab in patients with active psoriatic arthritis (PsA) and prior inadequate response/intolerance to tumour necrosis factor inhibitors. METHODS: Patients completing the 16-week phase III double-blind, placebo-controlled BE COMPLETE (NCT03896581) study entered the open-label extension, BE VITAL (NCT04009499). All patients in BE VITAL received 160 mg bimekizumab every 4 weeks. Safety and efficacy are reported to week 52. RESULTS: A total of 347/400 (86.8%) patients completed week 52. To week 52, the exposure-adjusted incidence rate/100 patient-years for ≥1 treatment-emergent adverse event (TEAE) was 126.0, and was 7.0 for serious TEAEs. The most frequent TEAEs were SARS-CoV-2 (COVID-19), oral candidiasis, nasopharyngitis and urinary tract infection. All fungal infections were mild or moderate in severity and localised; two patients discontinued the study due to oral candidiasis. No cases of active tuberculosis, uveitis or inflammatory bowel disease were reported. One sudden death occurred. Sustained efficacy was observed with bimekizumab from week 16 to |52 across clinical and patient-reported outcomes. At week 52, 51.7% bimekizumab-randomised and 40.6% placebo/bimekizumab patients (receiving bimekizumab from week 16 to 52) had ≥50% improvement in the American College of Rheumatology criteria. Complete skin clearance (Psoriasis Area and Severity Index 100) was achieved by 65.9% bimekizumab and 60.2% placebo/bimekizumab patients at week 52. Minimal disease activity was achieved by 47.2% bimekizumab and 33.1% placebo/bimekizumab patients at week 52. CONCLUSIONS: Bimekizumab demonstrated a safety profile consistent with previous reports; no new safety signals were identified. Sustained efficacy was observed from week 16 to 52.

Safety and Efficacy of Bimekizumab in Patients With Active Psoriatic Arthritis: Three-Year Results From a Phase IIb Randomized Controlled Trial and Its Open-Label Extension Study.

OBJECTIVE: To assess the long-term safety, tolerability, and efficacy of bimekizumab in active psoriatic arthritis (PsA). METHODS: Adult patients with active PsA who completed the double- and dose-blind periods of the BE ACTIVE randomized controlled trial were eligible to enroll in the open-label extension (OLE) study at week 48, after which patients received 160 mg of bimekizumab every 4 weeks. Safety and efficacy results are presented through 152 weeks. RESULTS: At week 152, 161 of 206 patients (78.2%) remained in the study. From weeks 0-152, 184 of 206 patients experienced ≥1 treatment-emergent adverse event (126.4 per 100 patient-years). The most frequent events were nasopharyngitis (7.6 per 100 patient-years), upper respiratory tract infection (6.8 per 100 patient-years), bronchitis (3.5 per 100 patient-years), and oral candidiasis (3.5 per 100 patient-years). Additionally, 47 of 206 patients had mild to moderate localized fungal infections (9.7 per 100 patient-years), including 24 of 206 patients who had Candida infections (4.6 per 100 patient years) and 19 of 206 patients who had oral candidiasis (3.5 per 100 patient years). Four patients had serious infections (0.7 per 100 patient-years); there were no reported cases of active tuberculosis, adjudicated major adverse cardiac events, or deaths. Efficacy demonstrated at week 48 was sustained in the OLE study. At week 152, nonresponder imputation analysis showed that 52.9% of patients (69.4% of observed cases) achieved the American College of Rheumatology criteria for 50% improvement, 57.7% (73.8% of observed cases) achieved 100% skin clearance per the Psoriasis Area and Severity Index, and 51.5% (67.5% of observed cases) achieved minimal disease activity. Patients also maintained improvements in pain, physical function, and health-related quality of life. CONCLUSION: The safety profile of bimekizumab was consistent with previous reports, with no new safety signals identified. Sustained joint and efficacy responses were observed over 3 years.

Small ubiquitin-like modifier 1 [corrected] mediates the resistance of prosthesis-loosening fibroblast-like synoviocytes against Fas-induced apoptosis.

OBJECTIVE: To study the expression of small ubiquitin-like modifier 1 (SUMO-1) in aseptic loosening of prosthesis implants and to investigate its role in regulating the susceptibility of prosthesis-loosening fibroblast-like synoviocytes (FLS) to Fas-induced apoptosis. METHODS: Specimens of aseptically loosened tissue were obtained at revision surgery, and the expression of SUMO-1 was analyzed by in situ hybridization. SUMO-1 levels in FLS were determined by quantitative polymerase chain reaction and Western blot analysis. Immunohistochemistry and confocal microscopy were used to study the subcellular localization of SUMO-1. The functional role of SUMO-1 in Fas-induced apoptosis of prosthesis-loosening FLS was investigated by small interfering RNA-mediated knockdown of SUMO-1 and by gene transfer of the nuclear SUMO-specific protease SENP1. RESULTS: SUMO-1 was expressed strongly in aseptically loosened tissue and was found prominently at sites adjacent to bone. Prosthesis-loosening FLS expressed levels of SUMO-1 similar to the levels expressed by rheumatoid arthritis (RA) FLS, with SUMO-1 being found mainly in promyelocytic leukemia protein nuclear bodies. Knockdown of SUMO-1 had no effect on spontaneous apoptosis but significantly increased the susceptibility of prosthesis-loosening FLS to Fas-induced apoptosis. Gene transfer of the nuclear SUMO-specific protease SENP1 reverted the apoptosis-inhibiting effects of SUMO-1. CONCLUSION: These data suggest that SUMO-1 is involved in the activation of both RA FLS and prosthesis-loosening FLS by preventing these cells from undergoing apoptosis. Modification of nuclear proteins by SUMO-1 contributes to the antiapoptotic effects of SUMO-1 in prosthesis-loosening FLS, providing evidence for the specific activation of sumoylation during their differentiation. Therefore, SUMO-1 may be an interesting target for novel strategies to prevent aseptic prosthesis loosening.

Modification of nuclear PML protein by SUMO-1 regulates Fas-induced apoptosis in rheumatoid arthritis synovial fibroblasts.

The small ubiquitin-like modifier (SUMO)-1 is an important posttranslational regulator of different signaling pathways and involved in the formation of promyelocytic leukemia (PML) protein nuclear bodies (NBs). Overexpression of SUMO-1 has been associated with alterations in apoptosis, but the underlying mechanisms and their relevance for human diseases are not clear. Here, we show that the increased expression of SUMO-1 in rheumatoid arthritis (RA) synovial fibroblasts (SFs) contributes to the resistance of these cells against Fas-induced apoptosis through increased SUMOylation of nuclear PML protein and increased recruitment of the transcriptional repressor DAXX to PML NBs. We also show that the nuclear SUMO-protease SENP1, which is found at lower levels in RA SFs, can revert the apoptosis-inhibiting effects of SUMO-1 by releasing DAXX from PML NBs. Our findings indicate that in RA SFs overexpression of SENP1 can alter the SUMO-1-mediated recruitment of DAXX to PML NBs, thus influencing the proapoptotic effects of DAXX. Accumulation of DAXX in PML NBs by SUMO-1 may, therefore, contribute to the pathogenesis of inflammatory disorders.

NEDP1, a highly conserved cysteine protease that deNEDDylates Cullins.

The ubiquitin-like protein NEDD8 is essential for activity of SCF-like ubiquitin ligase complexes. Here we identify and characterize NEDP1, a human NEDD8-specific protease. NEDP1 is highly conserved throughout evolution and equivalent proteins are present in yeast, plants, insects, and mammals. Bacterially expressed NEDP1 is capable of processing NEDD8 in vitro to expose the diglycine motif required for conjugation and can deconjugate NEDD8 from modified substrates. NEDP1 appears to be specific for NEDD8 as neither ubiquitin nor SUMO bearing COOH-terminal extensions are utilized as substrates. Inhibition studies and mutagenesis indicate that NEDP1 is a cysteine protease with sequence similarities to SUMO-specific proteases and the class of viral proteases typified by the adenovirus protease. In vivo NEDP1 deconjugates NEDD8 from a wide variety of substrates including the cullin component of SCF-like complexes. Thus NEDP1 is likely to play an important role in ubiquitin-mediated proteolysis by controlling the activity of SCF complexes.