Following The Data To The Heart: Atrium's Quest For Next-Gen Targeted RNA Delivery

There are events that make waves in any space, and last year in the RNA sector, M&A was an unmissable highlight. In 2025, we saw the acquisitions of Verve, Orbital, and Capstan for $1.3 billion, $1.5 billion, and $2.1 billion respectively — numbers that left many in across the pharma industry wowed. That is, until Novartis stepped up and said, “Hold my antibody,” acquiring Avidity Biosciences and its antibody-oligonucleotide conjugate (AOC) platform for $12 billion.

A few months later, Atrium Therapeutics launched, boasting a pipeline of two preclinical siRNA candidates targeting rare cardiomyopathies.

There were a handful of reasons why I was excited to sit down with Atrium’s CEO, Kath Gallagher — one of which being her background in communications. But besides anticipating a strong sense of kinship with a fellow writer/communicator, I was also intrigued to learn more about what it’s like to launch a new biotech in the growing oligonucleotide industry. Though Gallagher admitted that the modality itself is not what keeps her up at night, many of us know that bringing an RNA therapeutic into the rare disease community comes with its fair share of challenges and opportunities — modality-specific and otherwise.

“When you’re the first in an indication, your responsibility is to pave that path, not just for your drug, but for the patient community to have more therapeutic options,” Gallagher said.

In this two-part series, Gallagher shares more about her goals for Atrium following its spin-out from Novartis, articulating what it looks like and means to “pave a path” to greater patient access in rare cardiomyopathies. Here in part one, we start with a look into the formation of Atrium, sharing the “why” behind the company’s formation and what’s next for the company’s targeted delivery platform.

AOCs and Beyond: Designing A Flexible Delivery Toolbox for Cardiology

By now, we all know the basic story behind the acquisition. In acquiring Avidity, Novartis gained three late-stage AOCs targeting rare neuromuscular disorders.

But tucked quietly into the Novartis press release was this statement: “The acquisition will follow the separation of Avidity’s early-stage precision cardiology programs.”

As the fifth and seventh programs in development under Avidity’s roof, Gallagher admitted that the cardio programs didn’t get the amount of “love” they should have. Much like individual people, these two programs in the cardiomyopathies space had their own rich identities and needs. Not only is there no regulatory path for working within these indications, but given the delivery challenges facing the RNA space to date, cardiology has been largely untouched by the siRNA/oligo space. Being one of the first in a class of medicine to target ultra rare cardiomyopathies (namely PRKAG2 syndrome & PLN cardiomyopathy) demands the ability to rapidly change course to follow the data. This need for “scrappiness” and quick thinking ultimately dictated the formation of Atrium.

Given the challenges of delivery today across the RNA space, it shouldn’t come as a surprise that Atrium will be making a concerted effort to refine its targeted delivery platform.

“As our conversations with Novartis progressed, we decided not only to create Atrium to focus on the development of both of these cardiomyopathy programs, but to continue to work on the platform technology in this spin out as well,” she explained.

Though Novartis is not a shareholder in Atrium, the companies have entered into a cross-licensing arrangement for the platform technology, enabling both companies to benefit from any delivery advancements.

Now, to be clear, Avidity was the first to bring an AOC into the clinic for myotonic dystrophy and, indeed, Atrium’s first two candidates are AOCs. However, Gallagher was clear that the company is making a concerted effort to not just refer to their platform as the “AOC platform.” Rather, part of the company’s formation is to explore what a next-gen targeted RNA delivery platform looks like — AOC or otherwise.

“We have been doing a number of experiments over the last few years to look at different methods of delivery,” she explained. Interestingly, though the AOC platform turned out to be Avidity’s crown jewel, antibodies weren’t always part of the plan.

“The original plan was actually to rely on lipid-based delivery,” she continued. “But we followed the data, which told us to make the shift to antibody-based delivery. As we’re thinking about Atrium, we are now asking the question: What makes sense when you’re treating cardiac muscle versus skeletal muscle? There may be differences. So, we have this flexibility to look at what ‘next-gen’ targeted delivery might look like.”

Innovation in delivery can mean a variety of different things, including, of course, working on the delivery vehicle/mechanism itself or the linker. But what is often understated is the important role the RNA cargo can play in the successful delivery of a therapeutic. Working to improve the potency and durability of the siRNA cargo has been Atrium’s first prerogative, leaving themselves open to opportunities to work with or without antibodies moving forward.

“We joke that the antibody is like the magic school bus,” Gallagher said. “The antibody is just delivering the RNA to where it needs to go; the antibody isn’t there to be a therapeutic. It’s just a tool. So, if we need a different tool, we can come up with a different tool. Over time, I want us to have the flexibility to keep following the data. If we see that an antibody isn’t the best delivery mechanism for cardiomyopathies, we have other ways to go about it.”

Stay tuned for part 2, in which Gallagher and I discuss the nuances of working with an RNA therapeutic in cardiomyopathies and what it will take (beyond successful delivery) for RNA therapeutics to have a greater therapeutic & commercial impact.