Lund, Sweden, September 7, 2026
SynAct Pharma AB has reported further analyses from its Phase 2b ADVANCE clinical trial of resomelagon (AP1189) in patients with rheumatoid arthritis (RA), with the findings reinforcing observations from the company’s Phase 2b EXPAND study and supporting plans to advance the program toward Phase 3 development. The additional analysis focused on identifying patient characteristics associated with response to resomelagon and showed encouraging activity among patients with elevated inflammatory biomarkers. SynAct said it plans to engage with the U.S. Food and Drug Administration (FDA) during the fourth quarter of 2026 to discuss the design of a potential Phase 3 program. The company continues to evaluate resomelagon as an investigational treatment intended to promote resolution of inflammation rather than simply suppressing inflammatory signaling.
ADVANCE Analysis Shows Response in RA Patients
The Phase 2b ADVANCE study evaluated resomelagon in patients with active RA who had an inadequate response to conventional treatment. In the newly reported analysis, SynAct examined treatment effects according to baseline levels of high-sensitivity C-reactive protein (hsCRP), an established biomarker associated with systemic inflammation. Among patients with stable background therapy and elevated hsCRP, the analysis showed a stronger treatment response with resomelagon. In the relevant subgroup, the ACR20 response rate was 79% with resomelagon compared with 55% for placebo, representing a clinically meaningful numerical difference between the treatment groups. The analysis is particularly relevant because it may help identify a biomarker-defined patient population that could benefit most from resomelagon. SynAct said the findings were consistent with observations from its earlier EXPAND Phase 2b study, strengthening the rationale for further development. However, the subgroup analysis is exploratory and should not be interpreted as definitive proof of efficacy. Confirmation in a larger, adequately powered Phase 3 trial will be necessary to determine whether the observed treatment effect can be reproduced across a broader RA population.
Resomelagon Targets Resolution of Inflammation
Resomelagon is an investigational, oral small-molecule drug designed to activate pathways involved in the body’s natural resolution of inflammation. This mechanism differs from many established RA therapies that primarily work by suppressing inflammatory pathways. SynAct’s development strategy is based on the concept that actively promoting resolution may help restore inflammatory balance while potentially supporting tissue recovery and reducing persistent inflammation. The company is developing resomelagon for inflammatory diseases where unresolved inflammation contributes to disease progression and symptoms. In rheumatoid arthritis, chronic inflammation can damage joints and impair physical function, creating a need for therapies that can provide sustained disease control. The Phase 2b findings provide additional evidence for investigating whether resomelagon’s resolution-based mechanism can translate into meaningful clinical benefit in appropriately selected patients. The company has also emphasized the potential importance of patient stratification in future development. The observed relationship between hsCRP levels and treatment response could provide a basis for refining eligibility criteria or enrichment strategies in subsequent clinical studies, although such an approach would need to be discussed with regulators and validated prospectively.
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SynAct Plans FDA Discussion for Phase 3
Following the additional ADVANCE analysis, SynAct plans to initiate discussions with the FDA in Q4 2026 regarding the design of a potential Phase 3 clinical development program for resomelagon in RA. Regulatory discussions are expected to address important elements such as the target patient population, endpoints, study design and other requirements for a registrational development program. The planned FDA interaction represents an important regulatory-development milestone, but it does not constitute FDA endorsement, approval or authorization of resomelagon. The candidate remains investigational, and its safety and efficacy have not been established for marketing purposes. SynAct will need to demonstrate reproducible clinical benefit and an acceptable safety profile in later-stage studies before any potential regulatory submission. The company said the latest findings, together with results from the EXPAND and ADVANCE Phase 2b programs, provide support for continued development. If the planned regulatory discussions lead to an aligned Phase 3 strategy, resomelagon could advance into a larger clinical program evaluating its potential role in treating rheumatoid arthritis driven by persistent inflammation. The next development stage will be important for determining whether the promising Phase 2b signals can translate into a clinically and statistically robust therapeutic benefit.
Source: SynAct Pharma press release
