In 2020, Emmanuelle Charpentier and Jennifer Doudna were awarded the Nobel Prize in Chemistry for developing CRISPR-Cas9 — a gene editing technology that has been described as one of the most significant scientific advances of the twenty-first century. For biotech investors, CRISPR is not just a scientific concept; it is a foundational platform technology that has spawned an entire sub-sector of publicly traded companies, generated billions in investment, and produced the first FDA-approved gene editing therapies. Understanding what CRISPR is, how it works, and where it stands in the drug development pipeline is essential context for investing in the genomic medicine space.
The Short Answer
| CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a technology that allows scientists to precisely edit DNA sequences within living cells. The CRISPR-Cas9 system — the most widely used version — works like a biological find-and-replace function: a guide RNA sequence directs the Cas9 enzyme to a specific location in the genome, where the enzyme cuts the DNA strand. The cell’s natural repair machinery then either disables the gene at the cut site or incorporates a new DNA sequence. In practical terms, this means scientists can correct disease-causing genetic mutations, disable harmful genes, or insert therapeutic sequences with unprecedented precision. |
The Discovery That Changed Biology
CRISPR sequences were first observed in the genome of E. coli bacteria in 1987, though their function was not understood at the time. Over the following two decades, microbiologists gradually recognized that CRISPR sequences were part of a bacterial immune system — a mechanism bacteria use to recognize and neutralize viruses that had attacked them before. The bacterial system stored fragments of viral DNA in the CRISPR sequence and deployed Cas proteins (CRISPR-associated proteins) to recognize and destroy matching sequences if the virus returned.
In 2012, Charpentier and Doudna published a landmark paper demonstrating that the CRISPR-Cas9 system could be engineered as a programmable gene editing tool — one that could be directed to cut any DNA sequence, not just viral sequences it had encountered before. The paper triggered an explosion of research, and within a year multiple laboratories had demonstrated CRISPR editing in human cells.
The first CRISPR-based therapy — developed by Vertex Pharmaceuticals and CRISPR Therapeutics for sickle cell disease and beta thalassemia, marketed as Casgevy — received FDA approval in December 2023, marking a historic milestone for the field.
How CRISPR-Cas9 Works at a Practical Level
The CRISPR-Cas9 system has two main components: the guide RNA and the Cas9 enzyme. The guide RNA (gRNA) is a short synthetic piece of RNA designed to match a specific sequence in the target genome — think of it as the address label for a specific location in the three-billion-base-pair human genome. The Cas9 enzyme is the molecular scissors: once the guide RNA finds its target sequence, Cas9 binds and cuts both strands of the DNA double helix.
After the cut, the cell repairs itself in one of two ways. Non-homologous end joining (NHEJ) — the cell’s default repair mechanism — rejoins the broken ends but often introduces small insertions or deletions that disrupt the gene’s function. This is used therapeutically when the goal is to disable a harmful gene. Homology-directed repair (HDR) uses a provided DNA template to repair the break, allowing a specific new sequence to be inserted — used when the goal is to correct a mutation or add a therapeutic gene.
Advanced CRISPR Technologies: Base Editing and Prime Editing
First-generation CRISPR-Cas9 editing required making double-strand DNA cuts, which can introduce unintended mutations. Newer CRISPR-derived technologies address this. Base editing, developed by David Liu at the Broad Institute, makes targeted single-letter changes to DNA without cutting both strands — dramatically reducing the risk of off-target edits. Prime editing, also from Liu’s lab, offers even greater precision, enabling targeted insertions, deletions, and all 12 types of point corrections without double-strand breaks or a DNA template.
These technologies form the basis of next-generation gene editing companies and are increasingly entering clinical development, expanding the universe of diseases that could theoretically be treated with CRISPR-based approaches.
Key Publicly Traded CRISPR Companies
Several major publicly traded companies are developing CRISPR-based therapies. CRISPR Therapeutics (NASDAQ: CRSP) and Vertex Pharmaceuticals co-developed Casgevy, the first approved CRISPR therapy. Intellia Therapeutics (NASDAQ: NTLA) is developing in vivo CRISPR therapies — treatments designed to edit genes inside the patient’s body, rather than requiring cells to be edited outside the body. Beam Therapeutics (NASDAQ: BEAM) is the leading base editing company. Editas Medicine (NASDAQ: EDIT) is another clinical-stage CRISPR company. Each represents a different approach to CRISPR delivery and application, and each carries its own clinical development risks.
What This Does Not Guarantee
| CRISPR technology does not guarantee therapeutic success. Delivery — getting CRISPR components to the right cells in the body — remains one of the field’s largest technical challenges, particularly for in vivo approaches targeting tissues beyond the liver. Off-target editing, immunogenicity (the patient’s immune system reacting to the CRISPR components), and manufacturing complexity are active areas of concern. Most CRISPR therapies approved or in late-stage development address genetic diseases in the blood, where cell extraction, editing, and reinfusion is technically feasible. Broader tissue targeting remains early-stage. CRISPR is a genuinely transformative platform, but the clinical and commercial path for any given application is far from assured. |
Key Takeaways
- CRISPR-Cas9 is a gene editing technology that uses a guide RNA and an enzyme to precisely cut and modify DNA sequences
- The technology was adapted from a bacterial immune defense system and was engineered as a programmable editing tool by Charpentier and Doudna, who received the 2020 Nobel Prize in Chemistry for the work
- Casgevy — developed by CRISPR Therapeutics and Vertex — became the first approved CRISPR therapy when it received FDA approval in December 2023 for sickle cell disease and beta thalassemia
- Advanced CRISPR technologies including base editing and prime editing offer greater precision with fewer off-target effects
- Major publicly traded CRISPR companies include CRISPR Therapeutics (CRSP), Intellia Therapeutics (NTLA), Beam Therapeutics (BEAM), and Editas Medicine (EDIT)
- Delivery — getting CRISPR components to the right tissues — remains the field’s primary technical challenge for in vivo applications
- CRISPR is a transformative platform technology, but clinical and commercial success for any individual program is not guaranteed
Sources
1. FDA — CRISPR Therapeutics / Vertex Casgevy approval: https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/casgevy
2. Nobel Prize 2020 — Charpentier and Doudna: https://www.nobelprize.org/prizes/chemistry/2020/press-release/
3. Doudna & Charpentier 2012 paper — Science: https://www.science.org/doi/10.1126/science.1225829
4. NIH — Genome editing: https://www.genome.gov/about-genomics/policy-issues/Genome-Editing
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