The Merck & Co-backed antibody developer had secured $100m in equity and debt but has withdrawn plans for an IPO that would have raised $54m at the top of its range.

Visterra, a US-based antibody therapeutics developer backed by pharmaceutical firm Merck & Co, suspended plans for its $50m initial public offering on Friday.

The company had initially filed for the IPO in January 2016, setting a target of $69m. It subsequently set the range last month for an offering that would have raised between $46.2m and $53.9m, only to withdraw the plans due to unfavourable market conditions.

Founded in 2007, Visterra is working on antibody-based treatments for diseases such…