Synartro AB: No serious adverse events to date in ongoing phase 1/2a clinical study of SYN321

Clinical study update

UPPSALA, Sweden, Jan. 9, 2026 /PRNewswire/ -- Synartro is advancing the candidate drug SYN321, a novel intra-articular treatment for knee osteoarthritis, through a phase 1/2a clinical study focused on safety, tolerability, PK, and early efficacy signals. The study was initiated in August 2025 following approval from the Swedish Medical Products Agency (MPA) and the Swedish Ethical Review Authority. The study has enrolled a total of 35 participants with knee osteoarthritis.

All four cohorts were recruited and treated within a four-month period: Cohort 1 (n=7), Cohort 2 (n=8), Cohort 3 (n=8), and Cohort 4 (n=12). Following review by the internal safety review committee (iSRC), the highest dose tested in Cohort 3 was approved for expansion in Cohort 4.

Cohorts 1-3 have completed the study in accordance with the protocol. Cohort 4 is ongoing, with follow-up assessments conducted at weeks 4 and 6. Last Patient Last Visit (LPLV) is scheduled for the first week of February 2026. Unblinding of the study is planned for the second week of March 2026, after which analyses of safety, tolerability, and pharmacokinetic (PK) data will be performed.

Interim safety and pharmacokinetic observations

Interim data generated to date are consistent with preclinical observations. No serious adverse events related to the investigational medicinal product (IMP) have been reported. Observed adverse events are consistent with those commonly associated with intra-articular injections. No allergic reactions or immunological safety signals have been observed to date. These observations are based on data available to date, and the study is ongoing.

Mean Cmax values in plasma from Cohorts 1 and 2 indicate very low systemic exposure to diclofenac. Cmax data from Cohorts 3 and 4 are pending. Plasma concentrations of diclofenac-derived by-products have been below the limit of quantification, supporting the intended slow-release characteristics of SYN321.

CONTACT:

For further information, please contact:

Magnus Hurst, CFO & acting CEO. Tel: [phone]. E-mail: [e-mail]

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