On June 25, Novartis announced the completion of its acquisition of all outstanding shares of Regulus Therapeutics. Approximately 56.374 million shares of Regulus were validly tendered, representing 74.49% of the issued shares; the remaining shares were subsequently acquired through a merger. As a result, Regulus has become an indirect wholly-owned subsidiary of Novartis, and its stock has been delisted from the Nasdaq.

In the previously disclosed acquisition plan, the transaction structure included an upfront payment of $7 per share in cash (totaling $800 million), as well as $900 million in contingent payments based on regulatory milestones for Farabursen, a small nucleic acid drug targeting miR-17 developed by Regulus.

Novartis’ acquisition of Regulus represents a proactive strategic move to strengthen its pipeline and expand its technology platform in the field of kidney diseases. But what made this biotechnology company, which focuses on microRNA therapeutics, an attractive addition to Novartis’ portfolio? The answer lies in its core product, Farabursen.

As Regulus’s core candidate drug, the clinical value of Farabursen was the key driver behind Novartis’s acquisition.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common hereditary kidney disease worldwide. Its etiology is closely linked to genetic factors, and it is classified as an autosomal dominant disorder. In February 2025, KDIGO released the “Guideline for the Management of ADPKD,” stating that there are approximately 12 million ADPKD patients globally, with an annual incidence of 5–10 cases per 100,000 people.

ADPKD is primarily caused by mutations in the PKD1 and PKD2 genes. Patients carrying these mutations develop multiple, progressively enlarging cysts in both kidneys. These cysts compress the physiological architecture of normal renal tissue, leading to gradual deterioration of renal function. Furthermore, cyst growth is often positively correlated with age, and symptoms become increasingly apparent as patients grow older.

Current treatment modalities primarily consist of pharmacological therapy and end-stage interventions. Existing medications, such as tolvaptan (a V2 receptor antagonist), can effectively delay the progression of autosomal dominant polycystic kidney disease (ADPKD) by inhibiting antidiuretic hormone signaling to reduce cyst fluid secretion, thereby significantly slowing the rate of cyst growth.

Although this drug can delay disease progression, it has significant side effects, including the risk of hepatotoxicity and pronounced adverse effects such as polyuria and dehydration. Furthermore, its approved indications are limited; it is suitable only for patients with rapidly progressive disease and requires concomitant use with other diuretics, thereby increasing treatment complexity.

The breakthrough of Farabursen lies in targeting the pathogenesis of ADPKD, enabling intervention in the disease process at its source.

In patients with ADPKD, genetic mutations lead to abnormally high intracellular expression of miR-17. Farabursen acts like a “key,” with a structure that precisely targets and binds to miR-17. This binding forms an RNA-DNA hybrid, which subsequently recruits the endogenous enzyme RNase H, ultimately leading to the degradation of miR-17.

When miR-17 is cleared, the “inhibitory lock” on the PKD1 and PKD2 genes is released. These two genes can then resume normal function, helping to reduce renal cyst growth and thereby slowing the progression of ADPKD.

In the Pkd1cko mouse model, eight weeks of Farabursen treatment reduced kidney volume by 42% and improved survival rates by 58%.

Results from the Phase 1b multiple ascending dose clinical trial completed in March 2025 demonstrated that Farabursen was well tolerated and exerted consistent effects on two key endpoints: a reduction in urinary polycystin (PC) levels, a biomarker reflecting cyst activity, and a decrease in height-corrected total kidney volume (htTKV), a core clinical metric for assessing disease progression.

This indicates that Farabursen inhibits cyst growth in ADPKD while avoiding the toxicity limitations of existing therapies. Notably, the potential clinical benefits and robust data evidence for Farabursen are clearly demonstrated through disease-progression-related biomarkers and clinical endpoints, such as urinary polycystin and height-adjusted total kidney volume (htTKV).

Comparison of Farabursen and Tolvaptan Drug Therapies

From a clinical positioning perspective, Farabursen offers a mechanism of action complementary to existing therapies: while current drugs primarily influence cyst growth indirectly by modulating fluid balance, Farabursen directly targets upstream regulators of cyst proliferation, thereby holding promise as a “First-in-class” breakthrough therapy for ADPKD.

Turning to the company itself, Regulus, founded in 2007, is a clinical-stage biopharmaceutical enterprise centered on microRNA regulation technology. Its development path has not been smooth. Early pipeline projects, such as RG-101 for hepatitis C virus (HCV) infection and non-alcoholic steatohepatitis (NASH), encountered setbacks due to drug safety issues.

In 2017, under the leadership of new CEO Jay Hagan, who brought 20 years of biopharmaceutical experience, Regulus shifted its focus to ADPKD, leveraging optimized microRNA-targeting technology to launch next-generation ASO (antisense oligonucleotide) drugs.

Prior to the acquisition, Regulus had completed 15 rounds of financing, raising a total of $480 million. The company went public via an initial public offering (IPO) on October 5, 2012, with an opening price of $4 per share. The most recent round was a post-IPO equity financing conducted on March 12, 2024. Detailed financing information is presented in the table below.

RegulusHistorical Financing Table (Source:Crunchbase）

Since its founding in 2017, another key factor enabling Regulus to rapidly advance its clinical pipeline has been its microRNA technology platform. This also constitutes the second layer of consideration behind Novartis’ full acquisition—namely, to supplement its own oligonucleotide drug development platform.

MicroRNAs, a class of endogenous non-coding RNAs, participate in key physiological processes such as cell proliferation and differentiation by regulating the expression of target genes. Aberrant expression of these genes is often closely associated with the onset and progression of various diseases, including autosomal dominant polycystic kidney disease (ADPKD).

Regulus’s technology platform enables precise intervention in microRNA function through small nucleic acid drugs, with its core breakthroughs manifested at two levels:

First, optimization of targeting specificity.Through chemical modification technologies (such as nucleotide backbone modifications and sugar moiety modifications), small nucleic acid drugs developed by Regulus can efficiently recognize and bind to specific microRNAs (e.g., miR-17, the target of Farabursen), significantly enhancing targeted binding efficiency while minimizing effects on non-target microRNAs and reducing off-target effects.

Second, tissue-specific delivery.The key advantage of its technology platform lies in achieving organ-preferential drug exposure. Taking Farabursen as an example, the pharmacokinetic properties of the drug molecule are optimized to enable enrichment in renal tissue while reducing systemic exposure. This characteristic not only increases the drug concentration at the target organ but also lowers the risk of adverse effects caused by systemic distribution, offering a new approach to addressing the safety concerns associated with traditional small nucleic acid drugs.

For a long time, the field of nephrology has often been regarded as a niche sector.

Among the contributing factors are the inherent complexity of the diseases themselves and the high barriers to research and development. Kidney diseases encompass dozens of types, including primary and secondary forms, with highly individualized pathogenic mechanisms and a lack of “universal targets” akin to those in oncology. These challenges are also closely tied to the slow progression of kidney diseases, drug development cycles that often span 5–10 years, and the high risk of failure.

“Difficult R&D – Slow Returns – Cold Capital”This cycle has made nephrology a relatively niche sector, with most pharmaceutical companies adopting a cautious stance toward early-stage investment. However, the full acquisition of Regulus Therapeutics demonstrates that even overlooked therapeutic areas can produce emerging “champions.”

By continuously optimizing the targeting and tissue specificity of small nucleic acid drugs, Regulus leveraged Novartis’s R&D and commercialization resources to shorten the development cycle of Farabursen, thereby achieving rapid realization of its technological value.

For Novartis, this acquisition also carries dual value. On one hand, Farabursen fills the gap in its pipeline for autosomal dominant polycystic kidney disease (ADPKD), complements its existing renal disease medications, and strengthens its competitiveness in the field of chronic kidney disease;

On the other hand, Regulus’s microRNA technology platform synergizes with Novartis’s expertise in small nucleic acid drug development (such as delivery technologies and clinical trial capabilities), facilitating the expansion of microRNA therapeutics into broader disease areas (such as fibrosis and metabolic disorders).