New Gene Editing Safety Concerns May Crimp Therapy R&D

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By Jeannie Baumann

Biotech companies aiming to provide cutting-edge treatments by repairing the genetic code causing diseases could face a setback with the rise of new safety concerns.

Scientists with U.K.-based Wellcome Sanger Institute found a tool for editing genomes known as CRISPR/Cas9 can cause greater genetic damage in cells than geneticists previously thought. This creates safety implications for gene therapies using the tool as the unexpected damage could lead to dangerous changes in some cells.

The term “gene editing” covers a number of technologies with capability to change an organism’s DNA, and CRISPR/Cas9 has been considered one of the more promising ones. The authors of the paper, which appears in the July 16 issue of Nature Biotechnology, said their work has implications for using CRISPR/Cas9 to treat diseases and could spark a resurgence in other gene editing methods.

“It is important that anyone thinking of using this technology for gene therapy proceeds with caution, and looks very carefully to check for possible harmful effects,” Allan Bradley, corresponding author of the Nature Biotechnology paper, said in a July 16 statement. Gene therapy-based treatments are being tested to treat diseases ranging from genetic disorders to autoimmune diseases to heart disease, cancer, and HIV/AIDS.

One Company Unfazed

A spokeswoman for Editas Medicine, a Cambridge, Mass., pharmaceutical company that is developing therapies based on CRISPR–Cas9, said the paper’s findings aren’t “specifically problematic in our work to make CRISPR-based medicines.”

“With our focus on developing safe and effective medicines to treat people with devastating diseases, we’ve been answering these questions through our thorough pre-clinical work,” Editas’ Cristi Barnett told Bloomberg Law in a July 16 email.

Bradley and his co-authors said their research discovered CRISPR/Cas9 frequently caused extensive mutations that could lead to important genes being switched on or off, which could have major implications for CRISPR/Cas9 use in therapies. Some of these changes were too far away from the target genetic site to be seen with standard genotyping methods, they said.

This is one of what will be many papers that document the ongoing learning process about the risks and the benefits of genome editing, said R. Alta Charo, who co-led the committee that produced last year’s National Academies’ report on the science, governance, and ethics of human genome editing.

Using new technologies in clinical trials requires both initial and ongoing assessments as well as the willingness to rethink the decision to begin trials or to redesign the protocols, in light of new information and insights, Charo, a bioethicist at the University of Wisconsin-Madison, told Bloomberg Law in a July 16 email.

“One of the pitfalls in our public conversations about scientific and medical breakthroughs is that our excitement at the discovery and our anticipation of its ultimately successful uses somehow crowd out the reality of the long, careful, sometimes frustrating path toward that future success, to say nothing of the times a great idea turns out to be unworkable,” she said.

More Research Needed

Michele Calos, a Stanford University geneticist who is also the president of the American Society of Gene & Cell Therapy, expressed similar thoughts. “Gene editing methods such as CRISPR/Cas9 are useful tools with which we can potentially treat disease, but they’re new,” Calos told Bloomberg Law in a July 16 email. “There’s a lot left to learn, and that’s why gene and cell therapy researchers work so hard—to answer those questions and ensure the safety and long-term efficacy of groundbreaking technologies when applied to treat human disease.”

Barnett of Editas said while the authors of this paper were using CRISPR for their research, the generation of unintended genomic alterations, including those described in the paper, apply to all genomic medicine approaches.

“One of the great things about CRISPR is that there’s so much interest in it and so many people working on it. But, again, we are aware of, and not specifically concerned about, this latest bench research finding as we work to make CRISPR-based medicines,” she said.

FDA Policy Framework

These technologies can lead to new gene therapy products for treatment. The paper came out just five days after the Food and Drug Administration released a new framework for developing gene therapies. FDA Commissioner Scott Gottlieb said the agency has approved three gene therapy products in the past year and he expected the field to expand. But the agency didn’t specify whether those approvals involved CRISPR technologies.

“We look forward to working with the academic and research communities to make safe and effective products a reality for more patients, " Gottlieb said July 11. “But we know that we still have much to learn about how these products work, how to administer them safely, and whether they will continue to work properly in the body without causing adverse side effects over long periods of time.”

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