ZURICH, May 27 (Reuters) - Swiss drugmakers Novartis and Molecular Partners said on Thursday they will start clinical trials for an investigational medicine they are developing to treat COVID-19, with the aim of being able to seek approval next year.

The clinical trial program, which the companies are calling EMPATHY, is investigating the safety and efficacy of ensovibep in patients with COVID-19, who are in the early stages of infection, to prevent worsening symptoms and hospitalization.

The first study aims to enrol 400 patients to identify the optimal dosing, and a second late-stage trial would enrol 1,700 people, with results due in the first half of 2022.

Novartis, whose existing medicines have come up short in efforts to repurpose them against COVID-19, last year teamed up with smaller Molecular Partners on a program to develop a new therapy.

They said their drug showed "sustained binding against new variants", including those identified in Britain, South Africa, Brazil and India.

They are recruiting adults over 18 who test positive for COVID-19 and have experienced at least two mild or moderate symptoms of the disease within seven days of diagnosis.

"Ensovibep was built to resist viral mutations and indeed shows potent inhibition of all variants of concern to date, with the potential to maintain activity also for future variants," said Molecular Partners Chief Executive Patrick Amstutz in a statement.

"This type of broad spectrum activity is essential for any treatment of relevance for patients with COVID-19."

Molecular Partners is hoping to succeed in COVID-19 after its previous top drug prospect, abicipar, against macular degeneration, failed to win U.S. Food and Drug Administration approval last year. (Reporting by John Miller; Editing by Michael Shields and Jan Harvey)