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    Gene editing in 2026: a crash course

    Gene editing uses programmable tools such as CRISPR-Cas9 to change DNA inside living cells.[1] Since 2023 it has produced an approved medicine, Casgevy, for sickle cell disease and beta-thalassemia,[2][3] and as of October 2026 the first one-time CRISPR treatment given directly into the body is under FDA review, with a decision due by March 2027.[4]

    Editor reviewedStrict sourcingUpdated Gene editing and gene therapyLife sciencesHealth and medicine

    This crash course takes you from what gene editing is to where the field stands in October 2026.[1] It does not give medical advice. It describes published evidence and regulatory status.

    Why it matters

    DNA is the instruction manual inside every cell. Many inherited diseases come from a single error in that manual. Genome editing tools work like scissors that cut DNA at a chosen spot, so scientists can change the text.[1] The best-known tool, CRISPR-Cas9, is simpler, faster and cheaper than older methods, according to the US National Human Genome Research Institute.[5]

    The field has moved from lab bench to pharmacy. In late 2023, regulators in the UK and US approved Casgevy, the first CRISPR-based medicine, for sickle cell disease.[6][2] About 100,000 people in the US have sickle cell disease,[7] and the World Health Organization estimates 7.74 million people live with it worldwide.[8]

    CRISPR-Cas9 is an RNA-guided nuclease adapted from bacterial adaptive immunity.[9] The 2012 demonstration that a two-RNA structure directs Cas9 to make double-strand breaks, and could be reprogrammed, launched the modern field.[10] It earned a shared 2020 Nobel Prize in Chemistry.[11]

    Clinically, the field has reached its first regulatory approval and its first pivotal in vivo readouts. Casgevy has been approved in 39 countries as of August 2026.[12] Intellia’s lonvo-z met its Phase 3 endpoints in hereditary angioedema,[13] and its application is under FDA Priority Review.[4]

    The map of the field

    The field has four connected parts:

    • Editors. Cas9 nucleases cut both DNA strands.[10] Base editors change single letters without a double-strand cut.[14] Prime editors write small edits from an RNA template.[15]
    • Delivery. Cells can be edited outside the body and returned (ex vivo), or the editor can be delivered into the patient (in vivo). In vivo delivery is harder.[16] Lipid nanoparticles are good at reaching the liver, but reaching other tissues remains a challenge.[17]
    • Therapies. These include approved ex vivo products such as casgevy and in vivo candidates such as lonvo-z and CTX310.[18][19]
    • Governance. This covers regulators, payers and ethics bodies. Edits to body cells affect only the patient. Edits to reproductive cells would be inherited.[20] WHO issued global governance recommendations in 2021.[21]

    Key ideas

    Think of three generations of tools. The first, crispr-cas9, cuts DNA at a spot chosen by a guide RNA.[10] The second, base editing, works like a pencil that rewrites one letter.[14] The third, prime editing, works more like “search and replace” for short stretches of text.[15] Its inventors estimated that it could in principle fix up to 89% of known disease-causing variants.[22]

    Clinical in vivo editing so far has relied mainly on lipid nanoparticles that reach the liver.[17] The 2021 NTLA-2001 study used a lipid nanoparticle carrying Cas9 mRNA and a TTR-targeting guide to cut serum TTR by a mean 87% at 0.3 mg/kg.[23] Later in vivo programs include the KLKB1 knockout lonvo-z[18] and the ANGPTL3 knockout CTX310.[19] The other edge is customization. In 2025, a base editor targeted to a single patient’s variant was designed and manufactured in about six months.[24] In February 2026 the FDA published draft guidance on a “plausible mechanism” evidence framework for such individualized therapies.[25]

    Who the main players are

    • crispr-therapeutics (Zug, Switzerland) partners with Vertex Pharmaceuticals on Casgevy. Vertex leads commercialization, and the two split profits and costs 60/40.[26][27]
    • intellia-therapeutics develops lonvo-z and nex-z, two in vivo CRISPR therapies in late-stage trials or review.[4][28][29]
    • Beam Therapeutics develops base-editing therapies. Its BEAM-302 for alpha-1 antitrypsin deficiency entered a pivotal cohort in July 2026.[30]
    • Prime Medicine reported the first human prime-editing data in 2025.[31]
    • Eli Lilly agreed in 2025 to buy Verve Therapeutics, which develops a base editor that switches off PCSK9 to lower cholesterol.[32]
    • Academic medical centres such as Children’s Hospital of Philadelphia and Penn Medicine delivered the first personalized in vivo base-editing therapy, with NIH funding.[24][33]

    Where the frontier is (October 2026)

    • First in vivo approval. The FDA’s target action date for lonvo-z is 10 March 2027.[4]
    • Safety of in vivo editing. In October 2025 the FDA put a clinical hold on Intellia’s nex-z Phase 3 trials after a severe liver reaction, and the patient died in November 2025; the investigator reported septic shock from a perforated ulcer as the cause.[29][34] Both holds were lifted in January and March 2026 with added liver monitoring.[35] The in vivo safety debate page later in this course looks at what this means.
    • Younger patients and wider access. Casgevy is now approved in the US from age 2.[36] Paying for one-time therapies that can cost millions is driving new outcomes-based payment models.[37][38]
    • Next-generation editors in pivotal trials. These include base-edited cell therapy filings expected as early as the end of 2026[39] and a prime-editing filing planned for the first half of 2027.[40]

    The gene editing tracker, the last step in this course, lists dated milestones.

    Questions readers ask

    Is there an approved CRISPR medicine?

    Yes. Casgevy was authorised in the UK in November 2023 and approved by the FDA in December 2023 for sickle cell disease, and for beta-thalassemia in January 2024. In July 2026 the FDA extended it to children aged 2 and older.[6][2][3][36]

    Has any CRISPR therapy given directly into the body been approved?

    Not as of October 2026. The FDA accepted Intellia's application for lonvo-z for hereditary angioedema with a target action date of 10 March 2027. The company says it would be the first in vivo CRISPR-based therapy if approved.[4]

    What is the difference between base editing and prime editing?

    Base editing chemically converts one DNA letter into another without cutting both strands. Prime editing uses a reverse transcriptase and a special guide RNA to write small insertions, deletions or any single-letter change, also without a double-strand break.[14][15]

    Is editing embryos allowed?

    Germline edits would be inherited. NHGRI says most people agree germline cells should not be edited at this time, and NIH does not fund research to edit human embryos.[20][41]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      Genome editing is a set of methods for changing the DNA of organisms; the tools act like scissors that cut DNA at a chosen spot. confirmedas of 2026-10-10

    2. [2]

      On 8 December 2023 the FDA approved Casgevy, the first FDA-approved therapy using CRISPR/Cas9, for people aged 12 and older with sickle cell disease and recurrent vaso-occlusive crises. confirmedas of 2026-10-10

    3. [3]

      The FDA approved Casgevy for transfusion-dependent beta-thalassemia on 16 January 2024. confirmedas of 2026-10-10

    4. [4]

      On 8 September 2026 Intellia said the FDA had accepted its lonvo-z application with Priority Review and a target action date of 10 March 2027; the company says lonvo-z would be the world's first in vivo CRISPR-based therapy if approved. confirmedas of 2026-10-10

    5. [5]

      The US National Human Genome Research Institute describes CRISPR as simpler, faster, cheaper and more accurate than older genome-editing methods. confirmedas of 2026-10-10

    6. [6]

      On 16 November 2023 the UK medicines regulator, the MHRA, authorised Casgevy for patients aged 12 and over with sickle cell disease or transfusion-dependent beta-thalassemia, the first authorisation of a CRISPR-based medicine. confirmedas of 2026-10-10

    7. [7]

      Sickle cell disease affects approximately 100,000 people in the United States. confirmedas of 2026-10-10

    8. [8]

      WHO estimates that 7.74 million people were living with sickle cell disease in 2021, with 515,000 new births with the disease, and that sub-Saharan Africa accounts for nearly 80% of global cases. confirmedas of 2026-10-10

    9. [9]

      CRISPR-Cas9 comes from an adaptive immune system that bacteria use, which researchers repurposed as a programmable DNA-cutting tool. confirmedas of 2026-10-10

    10. [10]

      A 2012 Science paper by Jinek, Doudna, Charpentier and colleagues showed that a two-RNA structure directs the Cas9 protein to make double-stranded breaks in target DNA, and highlighted its potential for RNA-programmable genome editing. confirmedas of 2026-10-10

    11. [11]

      Jennifer Doudna and Emmanuelle Charpentier shared the 2020 Nobel Prize in Chemistry for developing CRISPR-Cas9 genome editing. confirmedas of 2026-10-10

    12. [12]

      As of August 2026, Casgevy was approved in 39 countries across North America, Europe and the Middle East. confirmedas of 2026-08-03

    13. [13]

      In the Phase 3 HAELO trial, a single infusion of lonvo-z reduced hereditary angioedema attacks by 87% versus placebo over weeks 5 to 28 (mean monthly attack rate 0.26 versus 2.10), and 62% of treated patients were attack-free and therapy-free versus 11% on placebo. confirmedas of 2026-10-10

    14. [14]

      Base editing, reported in Nature in 2016, converts one DNA base into another in a programmable way without cutting both DNA strands, with typically 1% or fewer unwanted insertions or deletions in the original experiments. confirmedas of 2026-10-10

    15. [15]

      Prime editing, reported in Nature in 2019, pairs an impaired Cas9 with an engineered reverse transcriptase and a prime editing guide RNA (pegRNA) that both finds the target and encodes the edit, allowing insertions, deletions and all 12 kinds of single-base change without double-strand breaks or donor DNA. confirmedas of 2026-10-10

    16. [16]

      Early CRISPR therapies edited cells outside the body (ex vivo); newer approaches deliver the editor into the patient (in vivo), which a 2025 review notes faces lower delivery efficiency, off-target effects and instability. confirmedas of 2026-10-10

    17. [17]

      Lipid nanoparticles can carry Cas9 mRNA and guide RNA into tissues, but reliably targeting tissues other than the liver remains a challenge. confirmedas of 2026-10-10

    18. [18]

      Lonvo-z (lonvoguran ziclumeran) is Intellia's one-time, in vivo CRISPR/Cas9 treatment for hereditary angioedema, designed to permanently lower kallikrein by inactivating the KLKB1 gene, and given in an outpatient setting. confirmedas of 2026-10-10

    19. [19]

      In November 2025 CRISPR Therapeutics reported Phase 1 data, published in NEJM, for CTX310, an LNP-delivered CRISPR therapy that edits the ANGPTL3 gene in liver cells; at the highest dose mean ANGPTL3 fell 73%, triglycerides 55% and LDL cholesterol 49%, with no treatment-related serious adverse events reported. confirmedas of 2026-10-10

    20. [20]

      Edits to somatic (body) cells affect only the person treated, while edits to germline (reproductive) cells are passed on to future generations. confirmedas of 2026-10-10

    21. [21]

      In July 2021 the World Health Organization issued its first global recommendations on governing human genome editing, including steps toward a trial registry and a confidential channel for reporting unethical or illegal research. confirmedas of 2026-10-10

    22. [22]

      The 2019 prime editing paper estimated that the method could in principle correct up to 89% of known disease-associated genetic variants. confirmedas of 2026-10-10

    23. [23]

      In a 2021 NEJM study, NTLA-2001, a lipid nanoparticle carrying Cas9 mRNA and a guide RNA targeting the TTR gene, given by infusion, lowered blood TTR protein by a mean 87% at the 0.3 mg/kg dose, with mainly mild adverse events. confirmedas of 2026-10-10

    24. [24]

      In 2025 a team at Children's Hospital of Philadelphia and Penn Medicine designed and manufactured, within about six months, a personalized base-editing therapy delivered by lipid nanoparticles to the liver for an infant with severe CPS1 deficiency, a rare urea-cycle disorder. confirmedas of 2026-10-10

    25. [25]

      On 25 February 2026 the FDA published draft guidance on a "plausible mechanism" framework for generating evidence of effectiveness and safety for individualized therapies that target specific genetic conditions with a known biological cause; comments closed on 27 April 2026. confirmedas of 2026-10-10

    26. [26]

      CRISPR Therapeutics AG is headquartered in Zug, Switzerland, with a US subsidiary and research operations in Boston and San Francisco. confirmedas of 2026-10-10

    27. [27]

      Vertex leads global development, manufacturing and commercialization of Casgevy, and Vertex and CRISPR Therapeutics share its profits and program costs 60/40. confirmedas of 2026-10-10

    28. [28]

      Nex-z (nexiguran ziclumeran) is Intellia's CRISPR/Cas9 therapy targeting the TTR gene for transthyretin (ATTR) amyloidosis with cardiomyopathy and hereditary ATTR with polyneuropathy, developed with Regeneron. confirmedas of 2026-10-10

    29. [29]

      On 29 October 2025 the FDA placed clinical holds on Intellia's Phase 3 MAGNITUDE and MAGNITUDE-2 trials of nex-z after a patient dosed in MAGNITUDE had Grade 4 liver transaminase elevations and increased bilirubin. confirmedas of 2026-10-10

    30. [30]

      In July 2026 Beam dosed the first patient in the global pivotal cohort of its BEAM-302 trial in AATD-associated lung disease. confirmedas of 2026-10-10

    31. [31]

      In May 2025 Prime Medicine reported the first clinical data for prime editing in humans, from PM359, an ex vivo prime-edited stem cell therapy for chronic granulomatous disease (CGD); the first patient reached 58% DHR-positive neutrophils by day 15 and 66% by day 30, with no serious adverse events related to PM359. confirmedas of 2026-10-10

    32. [32]

      On 17 June 2025 Eli Lilly agreed to acquire Verve Therapeutics for $10.50 per share in cash plus a contingent value right of up to $3.00 per share; Verve's lead program VERVE-102 is designed to permanently turn off the PCSK9 gene in the liver to lower cholesterol. confirmedas of 2026-10-10

    33. [33]

      The personalized CPS1 therapy work was supported by grants from the NIH Somatic Cell Genome Editing program, other NIH funding and industry contributions. confirmedas of 2026-10-10

    34. [34]

      Intellia's August 2026 quarterly report states that the MAGNITUDE participant who had Grade 4 liver transaminase elevations and increased bilirubin after a nex-z dose died on 5 November 2025, and that the principal investigator reported the cause as septic shock secondary to a perforated duodenal ulcer, with a clinical course that also included acute liver injury treated with corticosteroids and an autopsy report supporting the clinical diagnoses. confirmedas of 2026-08-06

    35. [35]

      The FDA lifted the clinical hold on Intellia's MAGNITUDE-2 trial in January 2026 and the hold on MAGNITUDE in March 2026, after the company agreed to study modifications including enhanced monitoring of liver laboratory tests; enrollment then advanced in both Phase 3 trials. confirmedas of 2026-08-06

    36. [36]

      On 1 July 2026 the FDA expanded Casgevy's approval to patients aged 2 years and older with sickle cell disease or transfusion-dependent beta-thalassemia, 53 days after filing, under the Commissioner's National Priority Voucher pilot program. confirmedas of 2026-10-10

    37. [37]

      CMS notes that cell and gene therapies can cost millions of dollars, and designed its access model to lower prices for states and tie payment to outcomes. confirmedas of 2026-10-10

    38. [38]

      The US Cell and Gene Therapy Access Model is a voluntary CMS program in which CMS negotiates outcomes-based agreements with manufacturers, initially for sickle cell gene therapies from Vertex and Genetix Biotherapeutics; 34 state Medicaid programs plus Washington DC and Puerto Rico joined between January 2025 and January 2026. confirmedas of 2026-10-10

    39. [39]

      Beam plans to submit a Biologics License Application for risto-cel (formerly BEAM-101), a base-edited cell therapy for sickle cell disease, as early as year-end 2026. reportedas of 2026-08-04· forecast

    40. [40]

      The FDA granted PM359 Regenerative Medicine Advanced Therapy designation in June 2026, and Prime Medicine is working toward a BLA submission in the first half of 2027. confirmedas of 2026-08-06

    41. [41]

      NHGRI states that most people agree germline cells should not be edited at this time, and that NIH does not fund research to edit human embryos. confirmedas of 2026-10-10

    Revision history (2)
    1. Page created.
    2. Updated the nex-z death and clinical-hold citations to the superseding claims.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Gene editing in 2026: a crash course." ContentLora, updated Oct 10, 2026. https://contentlora.com/explain/gene-editing

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