Scribe Therapeutics IPO raises $155m as STX-1150 enters clinic
Scribe Therapeutics completed a busy second quarter by initiating its first-in-human Phase 1 trial of STX-1150, an epigenetic silencing therapy targeting PCSK9 for LDL cholesterol lowering, while also closing an upsized IPO that together with a concurrent Sanofi private placement generated approximately $155.5 million in gross proceeds. The Nasdaq-listed company (SCTX) said its combined cash position funds operations into the first half of 2029.
The Phase 1 study, opened in Australia in mid-2026, is evaluating the safety, tolerability, and LDL-C lowering activity of STX-1150 in adults with elevated LDL-C and increased atherosclerotic cardiovascular disease (ASCVD) risk. Scribe expects to report initial data from the single ascending dose portion of the study in the first half of 2027.
Platform and preclinical evidence
STX-1150 is built on Scribe's Epigenetic Long-term X Repressor (ELXR) technology, which is designed to repress PCSK9 transcription in liver cells without permanently altering the underlying DNA sequence. In non-human primate studies presented at the European Atherosclerosis Society Congress, a single administration of an STX-1150 prototype achieved PCSK9 silencing of up to 90% and LDL-C reductions of up to 68%. At a dose of 0.75 mg/kg, LDL-C reductions exceeding 50% were sustained for two years, with liver enzyme profiles comparable to saline controls and no adverse clinical observations in a dedicated toxicology study.
The company's rationale centres on the well-documented adherence problem in chronic lipid management: it cites studies showing that 50 to 70% of patients discontinue LDL-C-lowering medicines within one year. Scribe is positioning ELXR as a mechanism that could convert a cardiovascular prevention strategy from a daily or monthly regimen into a one-time or infrequent intervention, comparable to the protective profile seen in individuals with naturally occurring PCSK9 loss-of-function variants.
Beyond STX-1150, the California Institute for Regenerative Medicine (CIRM) awarded Scribe approximately $25.7 million in combined non-dilutive grants: $12.7 million for STX-1200, which targets the LPA gene using the company's X-Editor (XE) platform to lower lipoprotein(a), and $13.0 million for STX-1400, which targets APOC3 to address severe hypertriglyceridaemia including familial chylomicronemia syndrome. Both programmes are aimed at clinical entry as early as 2027, and preclinical surrogates have shown greater than 95% Lp(a) reduction and greater than 75% APOC3 editing in non-human primates, respectively.
Market and competitive context
The PCSK9 space is already well-populated. Approved monoclonal antibodies (evolocumab and alirocumab) deliver robust LDL-C lowering but require fortnightly or monthly subcutaneous injections, which contributes to the adherence gap Scribe is targeting. Inclisiran, a small interfering RNA therapy from Novartis, reduced dosing to twice annually but still requires clinic visits. A durable, single-dose epigenetic approach would represent a meaningful step change in convenience, though clinical translation of NHP efficacy data is notoriously difficult to predict, and Phase 1 safety data will be closely scrutinised given that epigenetic modifications, while reversible in principle, carry uncertain long-term implications in humans.
Scribe is not alone in exploring in vivo CRISPR for cardiovascular targets. Verve Therapeutics has advanced a base-editing programme targeting PCSK9 and ANGPTL3 into clinical trials, though Verve has encountered regulatory and safety questions that have added caution to the field. Scribe's co-founding link to Nobel laureate Jennifer Doudna and its collaborations with Sanofi and Eli Lilly provide scientific credibility and commercial optionality, but first-in-human safety data in 2027 will be the defining near-term test for investor and partner confidence.
On the financial side, Q2 2026 R&D expenditure fell to $8.8 million from $13.9 million in the prior year period, primarily owing to lower personnel costs and reduced preclinical spending, partially offset by clinical and manufacturing costs for STX-1150. Collaboration revenue declined to $1.9 million from $4.9 million, and the net loss narrowed to $6.5 million from $9.9 million.