Regeneron committed up to $2.3 billion to Parabilis Medicines to develop antibody–Helicon conjugates aimed at intracellular targets described as “historically undruggable.” The collaboration includes a $450 million upfront payment and $75 million equity investment tied to Parabilis’ next financing, plus milestone payments totaling up to ~$2.2 billion across five initial targets and tiered royalties. The same Helicon partnership structure surfaced in deal coverage, reinforcing the emphasis on pairing VelocImmune-derived antibodies with Helicon peptides for cell penetration and intracellular protein modulation. For investors, the move signals continued funding into next-generation conjugate formats, particularly where conventional small molecules face binding-site constraints.