Genentech is doubling down on its commitment to New Haven biotech Arvinas, extending the duo’s partnership and tacking an additional $350 million onto the total deal value.

The companies have been working together since 2015, with Genentech licensing Arvinas’ platform for protein degradation

Arvinas plans to tag certain disease-causing proteins for destruction by recruiting an E3 ligase to the target, thereby sending the protein to the cell’s natural “garbage disposal” called the ubiquitin-proteasome system.