Atalanta Therapeutics: Reaching the Unreachable in Huntington’s Disease

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Atalanta Therapeutics: Reaching the Unreachable in Huntington’s Disease

by Pascal Krotee, PhD

RiverVest Principal

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The promise of broad and durable gene silencing using RNA interference

(May 15, 2026) Huntington’s disease (HD) has long stood as one of the most challenging neurodegenerative disorders to address therapeutically. Despite a clear genetic cause and decades of research, progress toward disease-modifying treatments has been limited.

In recognition of Huntington’s Awareness Day, we’ve asked RiverVest Principal Pascal Krotee, Ph.D., to explain the underlying biology of this devastating disease and how advances in RNA biology are reshaping what may be possible, opening the door to interventions that could meaningfully alter its course.

A Disease Defined by Its Genetics and Profound Burden

Huntington’s disease is caused by a mutation in the huntingtin (HTT) gene, specifically an expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats. This mutation results in the production of an abnormal, elongated huntingtin protein that forms toxic aggregates within neurons. Over time, this drives progressive neurodegeneration, particularly in deep brain regions responsible for movement, cognition, and behavior.

What makes HD especially devastating is not only its biology, but its inheritance pattern and timing. The disease is autosomal dominant, meaning each child of an affected parent has a 50% chance of inheriting the mutation. Onset typically occurs in patients during their 30s or 40s, often after they have started families, with symptoms worsening over 15 to 20 years.

Huntington’s patients experience a combination of psychiatric, cognitive, and motor symptoms. Early manifestations often include irritability, impulsivity, and subtle cognitive decline. As the disease progresses, these give way to more severe impairments, including chorea (involuntary movements), dementia, and loss of motor control. Ultimately, complications such as aspiration pneumonia or suicide contribute to mortality.

For families and caregivers, the burden is profound and cumulative, as patients gradually lose independence and require increasing levels of support.

Why Huntington’s Has Been So Difficult to Treat

Despite the clarity of its genetic origin, Huntington’s disease has proven difficult to treat for several reasons:

First, approved therapies remain primarily symptomatic rather than disease-modifying. Vesicular monoamine transporter 2 (VMAT2) inhibitors, for example, are used to reduce motor symptoms, primarily chorea, while other agents are used to manage psychiatric and cognitive manifestations. While these therapies can provide relief, they do not slow or halt disease progression and can carry serious side effects, including depression and fatigue
Second, the target itself—the HTT protein—is expressed throughout the brain, including deep structures that are difficult to access therapeutically. Delivering drugs to these regions in a safe, effective, and durable manner has been a central challenge.
Finally, prior therapeutic approaches have faced limitations. Early small molecule splicing modulators have shown promise but have raised safety concerns. Antisense oligonucleotides (ASOs) and earlier RNA interference (RNAi) strategies demonstrated target engagement but struggled with distribution, durability, or tolerability in the central nervous system (CNS), limiting their ability to achieve meaningful clinical efficacy.

Together, these challenges have slowed progress, even as the underlying biology has remained well understood.

Recent Advances Enabling New Therapeutic Approaches

Advances in RNA biology, combined with lessons learned from earlier clinical programs, have enabled a new generation of approaches designed to overcome the limitations of prior modalities. In particular, innovations in RNAi are improving the ability to selectively suppress disease-causing genes with greater precision.

At the same time, advances in RNA design are beginning to address one of the central barriers in CNS therapeutics: achieving broad and durable action across relevant brain regions while maintaining an acceptable safety profile.

These developments are not occurring in isolation. The broader neurodegenerative field has contributed important insights into biomarker development, trial design, and patient selection, helping to define clearer pathways for clinical evaluation.

A Differentiated Approach from Atalanta Therapeutics

Within this evolving landscape, RiverVest portfolio company Atalanta Therapeutics represents a compelling example of how scientific innovation can translate into therapeutic potential.

Atalanta is an emerging biotechnology company developing treatments for intractable diseases of the central nervous system. The company’s approach centers on divalent small interfering RNAs (di-siRNAs), which consist of two chemically modified siRNA molecules linked together. This design enables more effective distribution within the CNS and more durable knockdown of targets compared to earlier RNAi approaches.

Importantly, this platform has demonstrated the ability to reach deep brain regions implicated in HD that have historically been difficult to access therapeutically. Preclinical work has shown potent and sustained reduction of HTT expression in these regions, with a favorable balance between efficacy and safety.

This combination of broad distribution, durability, and specificity addresses several of the key limitations that have constrained prior approaches.

“Atalanta’s robust preclinical data gave us conviction that they’d overcome some of the shortcoings that have affected others in the RNA interference space….if their unique chemistry could stop the progression of the disease, that would be the Holy Grail – giving patients a longer and higher quality of life.”

PASCAL KROTEE, PHD

Principal

RiverVest Venture Partners

What Success Could Mean for Patients

If successful, Atalanta’s di-siRNA therapies could shift the treatment paradigm in Huntington’s disease.

At a minimum, slowing disease progression would represent a meaningful advancement, extending quality of life and preserving function for longer periods. Earlier intervention, potentially even in pre-symptomatic patients, could further amplify this impact.

Given the predictable genetic basis of HD, there is also the possibility of identifying and treating patients before significant neurodegeneration occurs. This raises the prospect of fundamentally altering the disease trajectory rather than simply managing its symptoms.

Early Signals and the Path Forward

Preclinical data supporting the di-siRNA approach have been encouraging, particularly in demonstrating durable knockdown of HTT in relevant brain regions. These findings, published in the scientific journal Nature Biotechnology prior to Atalanta’s formation, provided an important foundation for advancing into clinical development.

The company’s lead program, ATL-101, is expected to enter the clinic in H2 2026, with Phase 1 data expected in 2027. The primary objective of the initial Phase 1 study is to identify a potentially safe and effective dose for a subsequent multidose Phase 2 study.

As part of the Phase 1 study, the company plans to measure key biomarkers of disease to establish early clinical proof of concept.

A Strategic Fit for RiverVest Venture Partners

From an investment perspective, Atalanta reflects a broader strategy: pairing validated biology with differentiated technology to address significant unmet medical needs.

Huntington’s disease sits squarely within one of RiverVest’s core areas of focus: genetically defined rare diseases, where the link between target and outcome is well established. In this context, advances that improve the precision and delivery of therapeutics can unlock substantial value—both for patients and for investors.

Looking Ahead

Huntington’s disease remains a formidable challenge, but the landscape is changing. As the field moves from understanding to intervention, the convergence of biology, technology, and clinical insight is creating a new window of opportunity.

For patients and families, the stakes could not be higher. For the industry, this moment underscores a broader truth: when scientific rigor meets disciplined innovation, even the most intractable diseases can begin to yield.

About Atalanta Therapeutics

Atalanta Therapeutics is a biotechnology company developing treatments for intractable diseases of the central nervous system using RNA interference. Atalanta’s unique platform of divalent small interfering RNA (di-siRNA) is designed to enable durable, selective gene silencing throughout the brain and spinal cord. Atalanta is advancing a wholly owned pipeline of disease-modifying programs for Huntington’s disease, genetic epilepsy, severe chronic pain, and other neurological diseases in addition to partnered programs as part of a strategic collaboration with Genentech. Atalanta is headquartered in Boston, Mass.

About RiverVest

RiverVest Venture Partners is a leading venture capital firm building life science companies to address significant unmet needs of patients and deliver consistently strong returns to investors. With headquarters in St. Louis and offices in San Diego and Cleveland, RiverVest accesses forward-thinking research and clinical expertise at leading institutions across the country to found and fund biopharma and medical device companies.