Epigenetic editing against chronic hepatitis B: the study in Nature Biomedical Engineering with INGM’s contribution

CRMA-1001, developed by nChroma Bio together with SR-Tiget and INGM, silences viral DNA without cutting it. The first-in-human trial is already under way.

A study published on 21 September in Nature Biomedical Engineering, featured on the Nature homepage, describes a new therapeutic strategy against chronic hepatitis B based on epigenetic editing. The work stems from an Italian–US collaboration between the Boston-based biotech company nChroma Bio, the San Raffaele Telethon Institute for Gene Therapy (SR-Tiget) and the National Institute of Molecular Genetics “Romeo ed Enrica Invernizzi” (INGM).

Unlike gene editing, which cuts DNA — a problematic approach in hepatitis B, where viral integration is itself an oncogenic risk factor — epigenetic editing acts on the chemical marks that govern how genes are read. The therapy, named CRMA-1001, combines a catalytically dead version of Cas9, equipped with epigenetic effectors, with guide RNAs that direct the system to its viral target; the whole system is delivered by lipid nanoparticles. It silences both episomal cccDNA and viral sequences integrated into the host genome.

In mouse models the therapy reduced markers of viral activity to undetectable levels after six months; safety testing in non-human primates, with three monthly infusions at escalating doses, gave positive results. On the strength of these findings, nChroma Bio has launched a clinical trial in Hong Kong and New Zealand, with the first patient treated last January.

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