• 70% in vivo editing of human APOC3 in a single administration

• 76% triglyceride reduction after a single dose in murine disease model

New York, October 27, 2026 – Cellectis (Euronext Growth: ALCLS – Nasdaq: CLLS), a genome engineering company developing genetic medicines for diseases that today demand a lifetime of treatment, today announced the presentation of preclinical data supporting .HEAL-101, its in vivo base editing product candidate targeting APOC3 for severe hypertriglyceridemia (sHTG), at the Annual Congress of the European Society of Gene and Cell Therapy (ESGCT), being held October 27-30, 2026, in Hamburg, Germany.

.HEAL-101 is an APOC3-specific TALE base editor delivered as mRNA in liver-directed lipid nanoparticles (LNPs), designed to permanently inactivate APOC3, a genetically validated driver of elevated triglycerides, after a single intravenous administration. The poster presents an expanded preclinical data set for .HEAL-101, building on the initial dataset first disclosed by Cellectis on September 14, 2026.

“These expanded preclinical data reinforce the potential of our TALE base editing approach to achieve efficient and specific APOC3 editing following a single administration,” said Julien Valton, Ph.D., Vice President, Gene Therapy at Cellectis. “The substantial reduction in    triglyceride level observed across our preclinical study provide further support for the development of .HEAL-101 as a potential one-time treatment for patients with severe hypertriglyceridemia.”

Key findings presented at ESGCT

• Efficient and highly specific editing of APOC3 in vitro: In a human hepatic cell line, .HEAL-101 achieved a mean APOC3 editing rate of approximately 90%, without production of DNA double strand break at the target site.

• Efficient editing of human APOC3 in vivo: In a normolipidemic humanized liver mouse model, a single intravenous injection of LNP-mRNA edited the human APOC3 gene at a mean rate of approximately 65%, reaching up to 70%.

• Marked efficacy in a disease model: In a hyper triglyceridemic human APOC3 transgenic mouse model of hypertriglyceridemia, .HEAL-101 reduced APOC3 by 67% ± 12%, and triglycerides by 75% ± 11% (mean ± standard deviation).

• Liver-restricted activity: Editing was detected in the liver, with no significant activity in the other tissues analyzed.

These preclinical results support the continued development of .HEAL-101. Cellectis plans to initiate a Phase 1 investigator-initiated trial (IIT) in China with preliminary clinical data expected in the second half of 2027.

Poster Information:

Title: In vivo editing of human APOC3 by TALE base editor normalizes triglyceride levels in animal models

Presenter: Julien Valton, Ph.D., Vice President Gene Therapy at Cellectis

Presentation date/time: Thursday, October 29 from 2 to 4 p.m. CET. 

Poster number: P0208

The poster presentation is now available on Cellectis’ website.