Doudna-Backed Azalea Therapeutics Demonstrates Tumor Clearance With Single-Dose In Vivo CAR-T in Nature Study
A two-vector system inserts a CAR transgene at the TRAC locus inside the body, generating functional cancer-killing T cells without ex vivo manufacturing or lymphodepletion.
Overview
Researchers from UC San Francisco and UC Berkeley published results in Nature on March 18 showing that a single intravenous dose of gene-editing particles can create functional CAR-T cells inside the body that clear tumors in mice — without requiring the costly, weeks-long laboratory manufacturing process that currently limits the therapy to a fraction of eligible patients. The work, highlighted by spinout company Azalea Therapeutics, represents a significant step toward off-the-shelf cancer immunotherapy.
This follows earlier reporting by The Machine Herald on MagicRNA Biotech’s first-in-human proof-of-concept for in vivo CAR-T in autoimmune disease using lipid nanoparticles. The Azalea study takes a fundamentally different technical approach — using enveloped delivery vehicles and adeno-associated viruses to achieve permanent gene integration rather than transient mRNA expression — and targets cancer rather than autoimmune conditions.
How It Works
Conventional CAR-T therapy requires extracting a patient’s T cells through leukapheresis, shipping them to a specialized facility, engineering them with viral vectors, expanding the modified cells over two to four weeks, and reinfusing them — a process that typically costs more than $400,000 per patient. The Azalea approach eliminates this entire chain.
The study describes a two-vector system combining anti-CD3-targeted enveloped delivery vehicles (EDVs) with adeno-associated viruses (AAVs) optimized for T cell targeting, according to Azalea Therapeutics. The EDVs seek out T cells in the bloodstream and deliver CRISPR-based editing machinery that inserts a promoterless CAR transgene directly at the TRAC locus — the gene encoding the T cell receptor alpha chain. By placing the CAR under control of the endogenous TRAC promoter rather than an artificial one, the engineered cells achieve physiologically regulated expression, mimicking the way natural T cell receptors are controlled.
Justin Eyquem, an associate professor at UCSF and senior author of the study, emphasized that the method’s precision is its distinguishing feature. The system can “reliably genetically edit the right cells and the right part of those cell’s genomes,” substantially reducing the risk of off-target editing that could harm patients, as reported by STAT.
Preclinical Results
In humanized mouse models, a single administration of the two-vector system generated TRAC-CAR T cells representing up to approximately 20 percent of splenic T cells, according to Azalea Therapeutics. The in vivo-generated cells achieved complete B cell aplasia — a marker demonstrating that the CAR-T cells were actively targeting and eliminating B cells — and showed tumor clearance with sustained anti-tumor activity in models of hematologic malignancies.
Critically, the treatment worked without lymphodepletion, the chemotherapy conditioning regimen that conventional CAR-T protocols require to suppress the existing immune system before infusing engineered cells. Eliminating this step could significantly reduce toxicity, hospitalization time, and treatment costs.
What We Don’t Know
- Whether the mouse results will translate to humans. Azalea Therapeutics is advancing its TRAC-targeted in vivo CAR-T programs toward IND-enabling studies, but has not disclosed a specific timeline for first-in-human trials, per Azalea Therapeutics.
- How durable the engineered cells will prove over longer time horizons. The permanent gene integration at the TRAC locus theoretically supports long-lasting CAR expression, but this has not been tested in large-animal or human studies.
- Whether the two-vector system will prove safe in primates and humans, particularly regarding potential immune responses to the EDV and AAV components.
- How the approach will perform against solid tumors, which have historically resisted CAR-T therapy due to hostile tumor microenvironments.
A Crowded Field
Azalea is not alone in pursuing in vivo CAR-T. MagicRNA Biotech published first-in-human data in the New England Journal of Medicine showing its lipid nanoparticle-delivered mRNA approach achieved B cell clearance in lupus patients. Aera Therapeutics has nominated its own candidate, AERA-109, and targets a Phase I start in mid-2026. Capstan Therapeutics published preclinical data in Science demonstrating targeted lipid nanoparticle reprogramming of T cells in non-human primates.
The approaches differ in important ways. MagicRNA and Capstan use lipid nanoparticles that deliver transient mRNA — the CAR expression fades as the mRNA degrades, making the therapy potentially repeatable but short-lived. Azalea’s EDV/AAV system integrates the CAR permanently into the genome at a specific locus, aiming for durable, one-time treatment more analogous to conventional CAR-T, as described by STAT.
Azalea Therapeutics, based in Berkeley, California, was co-founded by Eyquem, Jenny Hamilton (who serves as president and CEO), and Nobel laureate Jennifer Doudna, who pioneered the CRISPR-Cas9 gene-editing technology. The company launched in November 2025 with $82 million in financing, according to STAT.