However, most of the Idera stockholders supported and voted in favour of the merger.
Under the terms of the original merger agreement signed in January this year, the termination will trigger a refund of $6m from BioCryst to Idera to cover transaction-related expenses.
BioCryst Pharmaceuticals board chairman Robert Ingram said: “We are focused on serving the interests of all stockholders in their desire for BioCryst to pursue a standalone strategy and continue our path to treating patients with rare and serious diseases.
“The board and management are steadfast in our commitment to capitalise on the opportunities in BioCyrst’s current portfolio and advance the promising candidates in the Company’s pipeline to generate stockholder value.”
BioCryst and Idera planned to combine their respective businesses for the development and commercialisation of drugs to treat patients with rare diseases.
The combined entity would have possessed a pipeline of two Phase II candidates and Phase III candidates each. They also planned to leverage each other’s drug discovery capabilities and clinical expertise to expand the development efforts.
Idera Pharmaceuticals CEO Vincent Milano said: “The board and shareholders of Idera overwhelmingly supported the proposed merger with BioCryst based on the strategic rationale, operating synergies and opportunity to create a stronger and more diversified rare-disease, focused organisation.
“Our tilsotolimod would have been one of the two centrepiece product opportunities of the combined company.”
As an independent company, Idera now plans to primarily continue developing tilsotolimod for anti-PD-1 refractory melanoma and investigate its application in other solid tumours.
Milano added that the company will explore any opportunities to further improve shareholder value and grow through business development.