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01/24/2018

Update on clinical studies of human gene editing

The January 22 edition of The Wall Street Journal carried an article the essential message of which was, “the Chinese are ahead of us in gene editing.”  Specifically, more human clinical trials are active in China than in the US using gene editing in some form to treat people with specific diseases.  Some of these trials use the “hot, new” CRISPR-Cas9 approach to gene editing.  Almost all of the active ones are in China, although one has recently been approved by regulators to begin in the U.S., at the University of Pennsylvania.  That one appears not yet to be recruiting patients.  In most of these “CRISPR” trials, cells are removed from a patient’s body, altered in the laboratory to make them more likely to treat the disease in question (in this case read: attack a cancer), and injected back into the patient.  They are thus variations on a 30-or-so-year-old approach of using cells that have been modified in some way to treat cancer.

The difference here is that the cells have their genes edited, and that raises potential safety risks, such as, what happens if the wrong genes are “edited,” and the altered cells go nuts and do something undesirable?  Because of this, human trials of gene editing in the U.S. are closely regulated, including having to pass scientific and safety review by the “RAC” (that’s for “Recombinant DNA Advisory Committee,” in case the acronym made any of you think of the Spanish Inquisition…then again, I have had researchers who have had to go through it suggest that the analogy is apt…).

The RAC was established back in the late 1970’s when drugs started being made with recombinant DNA, and trials of gene therapy using genes inserted into viruses were conducted.  A famous case of that work going awry raised concerns about oversight, and slowed things down substantially.  And as it stands now, the U.S. regulatory process for this work is cumbersome.  In China, not so much—a local ethics review board looks at a proposal, and off they go.  The WSJ makes it sound like informed consent for the Chinese studies may be a bit thin, too.  U.S. experts are quoted as saying not that we need less regulation, but that they (the Chinese) need more, to bring them back to our speed.

Perhaps so.  My point here is that this work is going on.  Examples like those cited here seem to me to fall under the existing regulatory regime for human trials, and don’t pose the same sort of ethical issues as the potential for inherited gene edits—that is, editing embryos and babies.  That’s a different kettle of fish.

One Chinese CRISPR trial appears not to alter cells outside the body, but actually try to administer the genetic material to make an edit to a cervical cancer-causing gene.  That poses similar safety concerns to other gene therapy approaches, including some with “zinc finger” editing technology, like a currently-active U.S. study to treat hemophilia, a disorder in which someone has a genetic flaw that makes them susceptible to excessive bleeding and the goal is to repair the offending gene.

In considering this work, I think it’s important to distinguish use of the gene-editing approach for incremental steps to treat human disease, like the cell therapy approaches, or true “gene therapy” approaches in which a “corrected” gene is administered to a patient, from the more problematic possibility of editing individuals in ways that can be inherited.  The latter is what worries me.  I wrote about this last November 9 and November 16.   And yes, the current Chinese work should be more closely regulated.  Doubt we have any control over that.

An FDA blog post from a year ago (by the former FDA Commissioner) provides a useful, brief discussion of the FDA’s approach to regulating various applications of genetic editing.  Worth reading.

This entry was posted in Genetics, Health Care and tagged , , . Posted by Jon Holmlund. Bookmark the permalink.

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