Extension Treatment Using EryDex System in Patients With AT Who Participated in the ATTeST-IEDAT-02-2015 Study

This was an international (North America, Europe, Africa, Asia and Australia), multi-center, prospective, open-label treatment study, designed to continue to provide the study medication to all patients who completed 12 months of treatment (including those treated with placebo) in the ATTeST-IEDAT-02-2015 trial, completed the study assessments, do not present safety contraindication to continuation of treatment, and provided informed consent. The study aimed to collect information on the long-term safety and efficacy of the trial treatment. Patients meeting all selection criteria received monthly infusions of EDS-EP (dose range of \~14-22 mg DSP/infusion). If this dose of EDS-EP was not tolerated, the patient was discontinued from the study. During the study, long-term efficacy assessments were performed every 6 months, while safety parameters were assessed at each monthly visit. The Schedule of Visits and assessments for the first 12 months were replicated for the second year onwards for patients who continued EryDex treatment beyond 12 months. The analysis of the EryDex long-term safety and tolerability was based on the occurrence of Treatment-Emergent Adverse Events (TEAEs), including Serious AEs and discontinuations due to AEs. The long-term effect was measured by the "Modified" International Cooperative Ataxia Rating Scale, (mICARS), Rescored mICARS, Clinical Global Impression of severity and change (CGI-S/C) and health-related Quality of Life (QoL; EQ-5D-5L scale). The ICARS, EQ-5D-5L and the CGI-C / S were administered by a properly qualified rater identified at each site who performed the ratings on the efficacy measures. The ICARS rater remained blinded to other assessments and did not have access to the safety data. The CGI rater did not have access to the ICARS ratings or safety data but was able to refer to other scales in scoring the CGI. All patients enrolled in this study have participated in Study ATTeST-IEDAT-02-2015, and there was no de novo enrollment of new patients. EryDel S.p.A (now Quince Therapeutics) decided to discontinue the IEDAT-03-2018 study in India due to the COVID-19 pandemic. On 13 Apr 2022, after the last patient completed one year of EryDex treatment, EryDel S.p.A. communicated the end of the open label extension study IEDAT-03-2018 and the stop of the EryDex treatment for patients in the context of this study.