US drugmaker Merck has announced plans to acquire Germany-based Rigontec, regarded as a pioneer in accessing the retinoic acid-inducible gene I (RIG-I) pathway as a novel and distinct approach in cancer immunotherapy, to induce both immediate and long-term anti-tumor immunity.

Rigontec’s lead candidate, RGT100, is currently in Phase I development, evaluating treatment in patients with various tumors.

Under the terms of the agreement, a Merck subsidiary will make an upfront cash payment of €115 million to Rigontec’s shareholders. Based on the attainment of certain clinical, development, regulatory and commercial milestones, the US pharmaceutical giant said it may make additional contingent payments of up to €349 million.

The transaction is subject to certain unspecified closing conditions. A date for completing the acquisition was not given.

“Rigontec’s immuno-oncology approach of engaging the innate immune system to safely eliminate cancer cells complements our strategy and our current pipeline,” said Eric Rubin, vice president of early-stage development, clinical oncology at Merck Research Laboratories. “We are eager to build upon Rigontec’s science as we continue our efforts in bringing forward meaningful advances for patients with cancer.”

The biotech was founded in 2014 as a spin-off of the University of Bonn, Germany, and up to now has raised close to €30 million from experienced life science investors including Boehringer Ingelheim Venture Fund, Forbion Capital Partners, High-Tech Gründerfonds, MP Healthcare Venture Management, NRW.BANK, Sunstone Capital and Wellington Partners Life Sciences.