City Therapeutics

Two decades ago, a small group of scientists proved something most of biology considered impossible: that you could reach inside a human cell and switch off a single gene on command. The mechanism was RNA interference. The company that turned it into approved medicines was Alnylam. Now several of the same people have regrouped a few blocks away in Cambridge, Massachusetts, under a new name - City Therapeutics - with a deceptively simple ambition: to redesign the RNAi drug from the molecule up.

City Therapeutics launched publicly in October 2024 with a $135 million Series A led by ARCH Venture Partners. Where many startups pitch a brand-new modality, City is doing something quieter and, in its own way, more audacious. It is going back to a technology that already works - RNAi drugs are on the market treating rare and common diseases - and asking whether the core components can be made meaningfully better. The answer it is betting on lives in the company's name itself: "cleavage-inducing tiny (city) RNAs," a class of engineered trigger molecules the company says can silence genes with improved potency and specificity.

That is a large claim, but it is not an idle one. Monoclonal antibodies took decades to move from laboratory curiosity to a foundational pillar of modern medicine. Maraganore's argument is that RNAi is on a comparable trajectory - and that the field's remaining limitations are engineering problems, not biological dead ends. City exists to solve two of them: making the trigger molecule sharper, and making delivery reach further than the liver.

City enters a field it helped create. The obvious comparison is Alnylam - the RNAi leader and the former home of several City founders - alongside Arrowhead Pharmaceuticals, Ionis, Silence Therapeutics, and the Dicerna franchise now inside Novo Nordisk. In a category this competitive, a startup's edge rarely comes from a slide. City's is threefold, and unusually concrete.

The founders. Few teams can claim to have built the field's defining company once already. That track record is why both Biogen and Bausch + Lomb signed research collaborations before City was two years old, and why blue-chip crossover investors backed two rounds in quick succession.

The molecule. Rather than chasing new targets with existing chemistry, City re-engineers the trigger itself - a bet that incremental gains in potency and specificity compound across an entire pipeline.

The reach. Its ligand work aims squarely at RNAi's biggest commercial ceiling: getting beyond the liver. Solve delivery, and the addressable disease map expands dramatically.