For any company hoping to treat a patient with CRISPR genome editing, safety is perhaps the biggest concern. The technology relies on a bacterial enzyme that can slice and dice DNA. Several safety issues have surfaced that have given investigators—and occasionally investors—pause. The biggest concern is that Cas9, while roaming the genome to find the correct target gene, could accidentally latch onto a closely related sequence, perhaps with just a single mismatched base, and cleave in the wrong place. This molecular mistaken identity could be harmless, seamlessly patched up by the DNA repair network. Or it could be disastrous, deactivating a critical gene or potentially switching on a cancer-causing gene. That could mean the end not only of a promising clinical trial but worse, a devastating setback for the entire field.
These concerns are not unique to CRISPR: any programmable genome editor will have a slight chance of fixating on the wrong sequence. But the stakes are higher with CRISPR because of its widespread use and stratospheric expectations. Some off-target fears have been overblown. A study from a Stanford group documenting multiple off-targets in 2018 raised alarms, even though the data were collected on just three lab mice. Industry scientists and academic groups swiftly rebutted any notion that CRISPR-Cas9 was unsafe.26 Subsequent studies suggested that if unintended edits do occur, they are no more frequent than those that inevitably result from background radiation and the errors that naturally accumulate during DNA replication and cell division.
Scientists have devised many ways to improve on-target specificity, from the design of the guide RNA to the choice and design of Cas9 nucleases.27 Concerns were also raised about on-target effects: Allan Bradley, a highly respected mouse geneticist and former director of the Sanger Institute, prompted another mini CRISPR crisis when his group showed that CRISPR-Cas9 can cause larger deletions than expected at the target site.28 Barrangou summed up the sentiment: “Keep calm and CRISPR on!”
Another safety issue is anticipating what happens when a bacterial protein is injected into patients. Porteus and colleagues found that many individuals carry antibodies to Cas9, suggesting they have been previously exposed to bacteria that express the protein.29 This is not surprising; after all, the immune system is designed to detect foreign proteins. A variety of methods—including selecting Cas9 enzymes from different bacteria or modifying the surface of the protein to make it less immunogenic—should minimize the risk of an undesirable immune response.30
Yet another scare flared up in 2018, when two highly publicized reports suggested that genome editing with CRISPR might increase the risk of genomic instability and cancer predisposition by selecting against the function of p53, the most frequently mutated tumor suppressor gene. Among many commentaries mulling over the significance of these findings was David Lane, who dubbed p53 “the Guardian of the Genome.” Lane and Teresa Ho said that this episode was a “cautionary rather than apocalyptic tale,” just like “every therapeutic endeavor of the past and future.”31 The case for using genome editing as part of a life-saving T-cell transplant in a 75-year-old cancer patient might be very different to editing cells to correct a Mendelian gene defect in a baby.
These issues were mostly taken in stride by the CRISPR companies. By July 2020, the big three biotechs had a combined market cap of $10 billion. And yet, the question of who actually owned the rights to the invention of the CRISPR revolution was still unresolved.
I. PICI likes to name its clinical trials after famous musicians. Along with Sinatra, it is also organizing trials named after Prince, Gustav Mahler, Cole Porter, Mozart (“Amadeus”), and country music star Tim McGraw, a longtime cancer research advocate.
II. Bosley’s father, Richard Bosley, designed and built the iconic Bosley GT MK I sports car in the 1950s.
III. Avila Therapeutics developed drugs that bind covalently to their target, which is unconventional in drug discovery.
IV. Caribou is an abbreviation for CRISPR-associated ribonucleic acid; the company logo sports a pair of antlers in the shape of a single-guide RNA.
V. Bermingham has since launched a new company called Triplet Therapeutics, a start-up targeting diseases like Huntington’s disease, which are caused by the expansion of triplet repeat DNA sequences.
VI. The dystrophin mutation was first observed in a Cavalier King Charles Spaniel, then bred into a line of beagles, which provide a better physiological match to humans.
CHAPTER 13 PATENT PENDING
“A few years ago with my colleague Emmanuelle Charpentier, I invented a new technology for editing genomes. It’s called CRISPR-Cas9.”1 Doudna raised a few eyebrows with that offhand remark during a TED talk in London in 2015, which made light of a billion of years of evolution, not to mention the competing efforts of a few other investigators. But it is fairly ingrained in the popular culture. In November 2019, Alex Trebeck read a question on Jeopardy:
JENNIFER DOUDNA & EMMANUELLE CHARPENTIER ARE CO-INVENTORS OF THE REVOLUTIONARY TOOL CRISPR TO EDIT THESE IN THE BODYI
Lest we forget, bacteria clearly invented CRISPR many hundreds of millions of years ago. But the legal question of who invented CRISPR genome editing technology is very real—and really important. At stake are commercial rights to a technology potentially worth billions of dollars. Law professor Jacob Sherkow calls it “the most monumental biotech patent dispute in decades.”2 At the heart of the dispute is the Broad Institute, the base of Feng Zhang, versus the University of California (UC), home of Doudna at Berkeley, in collaboration with Charpentier and her host institution.
So who “invented” the revolutionary CRISPR gene-editing technology? The transatlantic team that devised the single-guide RNA and showed that Cas9 could be programmed to cut DNA on demand in June 2012? Or the group that first demonstrated editing of human DNA using CRISPR-Cas9 seven months later? What about other less-celebrated contenders, such as Virgis Šikšnys, who filed a patent application in March 2012? In his small office at the New York Law School in Tribeca, Sherkow enthusiastically guides me through the landmarks of the saga.
One might assume that, because the Doudna-Charpentier team published the first account of CRISPR-Cas gene targeting, the invention should belong to them. Had the CRISPR saga taken place twelve months later, that might be the end of the story. In April 2013, the criterion for awarding American patents changed to a “first to file” basis. Before then, however, applications were reviewed on a “first to invent” basis. Eight years after the first key publication, we still don’t have a definitive answer. Doudna and Charpentier, together with Jínek and Chyliński, filed their provisional US patent application in May 2012, shortly before submitting their manuscript to Science.3 The three patent co-owners were UC, the University of Vienna, and in an interesting twist, Charpentier herself. In Sweden, where Charpentier was based, academics enjoy “Professor’s privilege,” which grants them full rights to their own inventions. (Thus, Charpentier is both a co-inventor of her technology and a co-owner of it.) The triumvirate is known as CVC.