New regimens of benznidazole for the treatment of chronic Chagas disease in adult participants in indeterminate form or with mild cardiac progression (NuestroBen study): protocol for a phase III randomised, multicentre non-inferiority clinical trial

INTRODUCTION: Chagas disease (CD) is one of the most neglected diseases in the world. In Latin America, CD is endemic in 21 countries, with an estimated 70 million people at risk of infection. Current treatments are limited to two nitroheterocyclic compounds: nifurtimox and benznidazole (BZN). Each has significant limitations, including long duration and safety concerns. However, data from recently completed studies suggest that reduced-duration regimens may be equally effective while enhancing safety.

METHODS AND ANALYSIS: NuestroBen is a phase III, randomised, multicentre clinical trial designed to assess whether shorter (2- and 4-week) regimens of BZN are non-inferior to the standard 8-week treatment. A total of 540 adult participants with no evidence of organ damage (the indeterminate form) or with mild cardiac progression (mild electrocardiographic alterations and without systolic dysfunction or symptoms), all in the chronic phase of CD, will be recruited at six study sites in Argentina and two study sites in Bolivia. Participants will be randomised to receive one of the two shortened regimens of BZN (300 mg per day for 2 or 4 weeks) or standard treatment (300 mg per day for 8 weeks). The primary endpoint is sustained elimination of parasitaemia from the end of treatment through 12 months of follow-up. Secondary endpoints will assess sustained clearance of parasitaemia at 1, 4, 6 and 8 months of follow-up from the end of treatment, drug tolerability and adherence to treatment. NuestroBen will also evaluate whether two shortened regimens of BZN improve drug tolerability and treatment adherence compared with the current standard treatment while maintaining efficacy in participants with the indeterminate form of CD or with mild cardiac involvement.

ETHICS AND DISSEMINATION: In Argentina, this study was approved by Fundación de Estudios Farmacológicos y Medicamentos 'Luis M. Zieher' for its conduct at the Instituto de Cardiología de Corrientes 'Juana Francisca Cabral' (reference: NuestroBen-2020/2021) and the Instituto Nacional de Parasitología 'Dr. Mario Fatala Chaben' (reference: NuestroBen-2020/2021) by Comité Institucional de Ética de Investigación en Salud for the Centro de Chagas y Patología Regional de Santiago del Estero (reference: NuestroBen-2020-088/2021), by Comité de Ética en Investigación for the Hospital de Infecciosas F.J. Muñiz (reference: NuestroBen-2020-4037) and the Hospital General de Agudos D.F. Santojanni (reference: NuestroBen-2020-4039) and by Comité de Bioética for the Fundación Huésped (reference: NuestroBen-2020/2021). In Bolivia, it was approved by Comité de Ética en Investigación en Salud from the Universidad Autónoma Juan Misael Saracho (reference: NuestroBen-2020/2025). All participants are asked to provide written informed consent to participate. Recruitment processes started in July 2023, and as of 15 June 2025, 140 participants have been recruited. Findings will be shared with Argentinian and Bolivian public health officials and with the Chagas and tropical medicine communities via international conferences. Findings will also be published in medical journals.

TRIAL REGISTRATION NUMBER: NCT04897516.