Startup Scribe Therapeutics, spun out of Jennifer Doudna’s lab, emerged from stealth on 6 October with a next-generation CRISPR technology, armed with a $20-million series A round and a collaboration with Biogen. Two days later, Scribe cofounder Doudna, at the University of California, Berkeley, shared the Nobel Prize in Chemistry 2020 with Emmanuel Charpentier, now at the Max Planck Unit for the Science of Pathogens in Berlin, for “one of gene technology’s sharpest tools: the CRISPR/Cas9 genetic scissors.” Scribe, however, is working on developing new Cas endonuclease variants based on CasX enzymes (a distinct family of RNA-guided genome editors) to pursue its goal of developing CRISPR-based genetic therapies.
The archetypal CRISPR endonuclease Cas9 is bulky and fits poorly inside the adeno-associated viral (AAV) vectors commonly used in gene therapy. CasX, at ~980 amino acids, is smaller than the Cas9 (~1,200 amino acids) used by other early movers, including Editas Medicine — the first company to deliver an in vivo gene editing therapy into patients. Scribe has continued to optimize CasX specificity and activity using protein engineering.
