Clinical study update

UPPSALA, Sweden, Jan. 9, 2026 — Synartro is progressing its candidate drug SYN321, an innovative intra-articular therapy for knee osteoarthritis, through a phase 1/2a clinical trial focused on safety, tolerability, PK, and early efficacy indicators. The trial launched in August 2025 after receiving clearance from the Swedish Medical Products Agency (MPA) and the Swedish Ethical Review Authority. To date, the study has enrolled 35 participants with knee osteoarthritis.

Recruitment and treatment for all four cohorts were completed over a four-month window: Cohort 1 (n=7), Cohort 2 (n=8), Cohort 3 (n=8), and Cohort 4 (n=12). Following an evaluation by the internal Safety Review Committee (iSRC), the highest dose tested in Cohort 3 was approved for use in the expanded Cohort 4.

Cohorts 1 through 3 have finished the study as per the protocol. Cohort 4 is ongoing, with follow-up assessments scheduled at weeks 4 and 6. The Last Patient Last Visit (LPLV) is set for the first week of February 2026. Unblinding of the study is planned for the second week of March 2026, after which safety, tolerability, and pharmacokinetic (PK) data will be analyzed.

Interim safety and pharmacokinetic observations

Preliminary data collected so far aligns with preclinical findings. No serious adverse events linked to the investigational medicinal product (IMP) have been documented. The observed adverse events are typical of those associated with intra-articular injections. No allergic responses or immunological safety flags have been noted to date. These observations are based on currently available data, and the study remains ongoing.

Average plasma Cmax levels from Cohorts 1 and 2 show minimal systemic exposure to diclofenac. Cmax data from Cohorts 3 and 4 is pending. Plasma concentrations of diclofenac-derived by-products have been below the limit of quantification, confirming SYN321’s designed slow-release properties.

CONTACT:

For further information, please contact:

Magnus Hurst, CFO & acting CEO. Tel: +46 (0) 760 27 44 27. E-mail:

This news is provided by Cision