Across 30 European CTIS-authorized rheumatoid arthritis Phase II and Phase III trials, safety endpoints were the most common endpoint family, appearing in 17/30 trials (56.7%). Disease-activity and response measures formed the clinical core: DAS28/DAS appeared in 13/30 trials (43.3%), while ACR response and CDAI each appeared in 12/30 trials (40.0%).
Safety, adverse event, laboratory, ECG, or vital-sign endpoints appeared in 17/30 trials (56.7%). DAS28/DAS appeared in 13/30 trials (43.3%), ACR response in 12/30 (40.0%), CDAI in 12/30 (40.0%), and remission in 10/30 (33.3%).
RA endpoint selection is still anchored in conventional clinical disease activity: DAS28/DAS, ACR response, CDAI, remission, SDAI, and HAQ/function appear together as the dominant efficacy cluster, while safety is the most universal endpoint family.
ACR response and DAS28/DAS were the most frequent primary endpoint families, each appearing as primary in 7/30 trials (23.3%). In secondary endpoints, safety led with 12/30 trials (40.0%), followed by CDAI in 11/30 (36.7%) and ACR response plus DAS28/DAS in 10/30 each (33.3%).
| Endpoint family | Primary | Secondary | Exploratory / other |
|---|---|---|---|
| ACR response | 7/30 (23.3%) | 10/30 (33.3%) | 0/30 (0.0%) |
| DAS28 / DAS | 7/30 (23.3%) | 10/30 (33.3%) | 0/30 (0.0%) |
| Safety / AE / labs / ECG | 6/30 (20.0%) | 12/30 (40.0%) | 0/30 (0.0%) |
| CDAI | 3/30 (10.0%) | 11/30 (36.7%) | 0/30 (0.0%) |
| Remission | 3/30 (10.0%) | 9/30 (30.0%) | 0/30 (0.0%) |
| SDAI | 1/30 (3.3%) | 8/30 (26.7%) | 0/30 (0.0%) |
| HAQ / function | 1/30 (3.3%) | 8/30 (26.7%) | 1/30 (3.3%) |
| PRO / QoL / pain | 1/30 (3.3%) | 7/30 (23.3%) | 1/30 (3.3%) |
| PK / drug concentration | 2/30 (6.7%) | 7/30 (23.3%) | 0/30 (0.0%) |
| Immunogenicity / ADA | 0/30 (0.0%) | 5/30 (16.7%) | 0/30 (0.0%) |
Primary RA endpoint strategy is comparatively focused, with ACR and DAS28/DAS each used in 7 trials. Secondary endpoints are broader and carry the operational burden of safety, remission, CDAI, SDAI, HAQ/function, pharmacokinetics, and immunogenicity.
Phase II accounted for 22/30 trials (73.3%) and Phase III for 8/30 trials (26.7%). In Phase II, safety appeared in 16/22 trials (72.7%), DAS28/DAS in 11/22 (50.0%), and both ACR response and CDAI in 10/22 each (45.5%). In Phase III, ACR, DAS28/DAS, CDAI, SDAI, remission, and PRO/QoL/pain each appeared in 2/8 trials (25.0%).
Phase II RA studies are endpoint-dense because they combine dose, safety, PK, immunogenicity, and early efficacy readouts. Phase III endpoint use is more concentrated around clinically interpretable response and disease-activity outcomes.
The cohort included 13/30 RA-only unqualified trials (43.3%), 12/30 RA plus other autoimmune disease protocols (40.0%), 2/30 refractory or difficult-to-treat RA trials (6.7%), and one trial each for preclinical RA, ACPA-positive RA, and moderate-to-severe RA (3.3% each).
RA-specific or RA-subtype protocols showed stronger use of classic RA efficacy endpoints: ACR response and DAS28/DAS each appeared in 10/17 such trials (58.8%). Multi-disease autoimmune protocols were more safety-led, with safety endpoints in 8/13 trials (61.5%) and PK or EULAR response in 4/13 each (30.8%).
Four modality groups had enough trials for comparison: monoclonal antibodies in 12 trials, small molecules in 8, peptide/protein/enzyme products in 7, and cell therapies in 4. Safety appeared in 4/4 cell therapy trials (100.0%), 7/8 small-molecule trials (87.5%), 8/12 monoclonal antibody trials (66.7%), and 5/7 peptide/protein/enzyme trials (71.4%).
| Modality group | Trial count | Leading endpoint signals |
|---|---|---|
| Monoclonal antibody | 12 | Safety 8/12 (66.7%); CDAI 7/12 (58.3%); remission 6/12 (50.0%) |
| Small molecule | 8 | Safety 7/8 (87.5%); DAS28/DAS 4/8 (50.0%); low disease activity 3/8 (37.5%) |
| Peptide/protein/enzyme | 7 | ACR 6/7 (85.7%); DAS28/DAS 6/7 (85.7%); safety 5/7 (71.4%) |
| Cell therapy | 4 | Safety 4/4 (100.0%); EULAR response 2/4 (50.0%); DAS28/DAS 2/4 (50.0%) |
Cell therapy and small-molecule RA trials are especially safety-heavy, while peptide/protein/enzyme trials are the most consistently anchored to ACR and DAS28 efficacy outcomes. Monoclonal antibody trials show the broadest balance between safety, CDAI, remission, and response.
Across the 30 European RA Phase II and Phase III trials, the median interval from initial CTIS submission to first CTIS authorization was 100 days. Phase II trials had a median of 101 days, while Phase III trials had a median of 79 days.
For EU rheumatoid arthritis submissions, endpoint strategy and CTIS planning should be linked early: the same protocols that carry safety, PK, immunogenicity, disease activity, and PRO endpoints also require enough CTIS lead time to support multi-country authorization planning.
Beyond the core disease-activity endpoints, HAQ/function appeared in 9/30 trials (30.0%), PRO/QoL/pain in 7/30 (23.3%), immunogenicity/ADA in 5/30 (16.7%), and exploratory imaging or B-cell immune biomarker endpoints in 1/30 trial (3.3%).
Most European RA Phase II and Phase III trials remain clinically focused, but Phase II designs are where additional translational and patient-centered endpoints appear most visibly: HAQ/function, QoL, ADA, imaging, and immune-biomarker endpoints are mainly add-ons rather than dominant endpoint families.
DAS28: Disease Activity Score using 28 joints. ACR20/50/70: American College of Rheumatology response thresholds. CDAI: Clinical Disease Activity Index. SDAI: Simplified Disease Activity Index. HAQ-DI: Health Assessment Questionnaire Disability Index. PK: pharmacokinetics. ADA: anti-drug antibodies. CTIS: Clinical Trials Information System used for EU clinical trial submissions and authorizations.