Scribe Therapeutics is betting patients will accept a one-time cholesterol treatment because it edits gene expression rather than DNA, and the company says those changes could be reversed if something goes wrong.
In non-human primate testing, the lead candidate STX-1150 lowered LDL-C by just 51% to 68%, a level the report argues would still leave the sickest patients short of treatment goals even on top of statins, ezetimibe, and PCSK9 inhibitors. Two Natural Capital, the research firm behind the analysis, questions whether epigenetic editing is understood well enough to make good on the reversibility promise, and whether a one-time therapy that still requires standing medications is compelling enough to drive adoption. The firm's report does not disclose a position in Scribe's stock.
Ticker: Not stated in the source report (Scribe Therapeutics)
Research Firm: Two Natural Capital
Report URL: https://www.twonaturalcap.com/p/scribe-therapeutics-the-world-of?ref=shortreport.fyi
Position Disclosure: Not stated in the source report.
Thesis
Two Natural Capital's report argues that Scribe's epigenetic-editing platform may be technically differentiated but faces structural hurdles to commercial adoption for its lead candidate, STX-1150.
- Reversible Edit, Unproven: Scribe asserts that STX-1150's gene-expression changes can be reversed if problems arise, but the report says current understanding of epigenome editing may not be sufficient to reliably reverse effects once they occur.
- Insufficient LDL Drop: STX-1150 lowered LDL-C by 51% to 68% in non-human primates, a reduction the report argues would not be enough for patients inadequately controlled on statins, ezetimibe, and PCSK9 inhibitors.
- Standing Medication Still Needed: Even on an adherence-adjusted efficacy basis, the report says STX-1150 may still fail to get severe patients to LDL-C goals, undercutting the case for a one-time therapy that still requires statins and ezetimibe.
- Off-Target Methylation Risk: The report ties aberrant off-target methylation, shown in CRISPRoff-style systems to impair cellular growth, to cancer risk and to the severity of conditions like Rett syndrome and Fragile X syndrome, raising doubts about epigenetic editing's safety more broadly.
- ADD-Domain "Proof-Reading": Scribe's fusion protein incorporates the DNMT3A ADD domain, which the company says dramatically reduced off-target methylation while increasing target-site methylation in preclinical testing.
- CasX Delivery Edge: Scribe's CasX enzyme is about 40% smaller than Cas9/Cas12a and originates from bacteria that don't infect humans, which the company says could ease delivery and avoid pre-existing immunity.
- Single-Asset Dependency: STX-1150 is the only clinical-stage program among Scribe's three wholly owned candidates, with initial human data not expected until the first half of 2027.
- Underwhelming Field Precedent: Gene-editing therapies have broadly underperformed expectations to date; Casgevy remains the only FDA-approved gene-editing treatment and requires an arduous ex-vivo process.
Catalysts
- STX-1150 initial human clinical data, expected 1H 2027: would show whether the 51-68% LDL-C lowering seen in primates translates to humans and reveal the real-world off-target methylation profile.
- Evidence on reversibility of induced epigenetic changes, no date specified: would test Scribe's core safety pitch that unwanted edits can be undone after the fact.
- Scribe's stated cash runway through 1H 2029: marks the window before the company likely needs additional financing ahead of clinical proof.
Company Response
The report does not indicate that Scribe was asked for comment on its conclusions, and no direct response from the company to the author's findings is reported. It does cite claims Scribe has made publicly: that its CasX platform, the DNMT3A ADD-domain "proof-reading" step, and the potential reversibility of epigenetic changes could reduce off-target risk relative to permanent genome editing.
Notable Details
- Scribe went public in late July with three wholly owned programs, but only its LDL-C candidate is in the clinic, and initial human data are not expected until the first half of 2027.
- The baby KJ case, often cited as proof of gene editing's promise, is described as an isolated N-of-1 base-editing treatment for a liver disease that did not face the delivery challenges associated with non-liver applications.
- The report notes that many CRISPR companies are pursuing sickle-cell disease even though it is already the field's only FDA-approved indication, pointing to a crowded, copycat dynamic.
- Verve's unnamed CEO has suggested its LDL-lowering candidate, Verve-102, could eventually be priced like a one-time cardiovascular intervention such as a coronary stent, a comparison the report uses to frame pricing expectations for one-time cholesterol treatments.
"A patient experiencing statin side-effects can discontinue usage; a patient whose genome was inadvertently edited in the wrong place does not have such a simple option."
The author uses this comparison to capture the fundamental tradeoff between conventional cholesterol drugs and permanent genetic interventions.
FAQs
What is Scribe Therapeutics and what does it do?
Scribe Therapeutics is a publicly traded gene-editing and epigenome-editing therapeutics developer that went public in late July. It has three wholly owned candidates targeting elevated LDL-C, elevated Lp(a), and severe hypertriglyceridemia/familial chylomicronemia syndrome, with its LDL-C candidate STX-1150 the only program currently in the clinic.
What is STX-1150, Scribe Therapeutics' lead drug candidate?
STX-1150 is Scribe's lead cholesterol-lowering therapy, designed to alter gene expression rather than edit DNA directly. In non-human primate testing it lowered LDL-C by 51% to 68%, and the company says the induced changes could be reversed if harmful effects occur. Initial human clinical data are expected in the first half of 2027.
What does the Two Natural Capital report say about Scribe Therapeutics?
Two Natural Capital, the research firm behind the analysis, finds Scribe's epigenetic-editing technology "fascinating" but questions whether STX-1150's observed LDL-C reduction would be enough for the sickest patients and whether reversible off-target methylation is meaningfully safer than permanent genome editing. The report does not disclose a position in Scribe's stock.
How does epigenetic editing differ from traditional gene editing like CRISPR?
Traditional gene editing changes the underlying DNA sequence, which cannot easily be undone once made. Epigenetic editing, the approach Scribe uses, alters gene expression without changing the DNA sequence itself, and Scribe argues this makes its effects reversible, though the report says the science of reliably reversing epigenetic changes after problems emerge is not yet established.
Why does the report question STX-1150's LDL-C lowering results?
STX-1150 lowered LDL-C by 51% to 68% in non-human primates. The report argues that degree of reduction would not be sufficient for patients not adequately controlled on statins, ezetimibe, and PCSK9 inhibitors, or for those already controlled only by that three-drug combination, meaning the sickest patients may still need standing medication after a one-time treatment.
What are the safety concerns around off-target methylation?
The report explains that CRISPRoff-style epigenetic editing, which lacks the DNMT3A ADD regulatory domain used in Scribe's system, can produce aberrant methylation at unintended sites, in some cases significantly impairing cellular growth. Aberrant methylation is described as a well-established cancer driver and a contributor to the severity of conditions like Rett syndrome and Fragile X syndrome.
When will investors get clinical data on STX-1150?
Scribe has said initial clinical data for STX-1150 are expected in the first half of 2027. The company states it has cash runway through the first half of 2029, giving it a multi-year window before needing additional financing.
How big is the market opportunity for LDL-lowering treatments?
PCSK9 inhibitors, an existing class of potent cholesterol drugs, generated roughly $5 billion in sales last year but reached less than 1% of the relevant patient population. The gap illustrates the distance between drug availability and real-world adoption that any new one-time LDL-lowering treatment, including STX-1150, would need to close.
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