Merck's Bold Bet on Lipoprotein(a) Inhibitor: A Game Changer in Cardiovascular Care?

In the ever-evolving landscape of cardiovascular therapies, Merck (NYSE: MRK) has made a strategic move that could reshape the treatment paradigm for millions of patients worldwide. On March 25, 2025, Merck announced an exclusive license agreement with Jiangsu Hengrui Pharmaceuticals Co., Ltd. for HRS-5346, an investigational oral small molecule Lipoprotein(a) (Lp(a)) inhibitor. This deal, valued at up to $1.97 billion, positions Merck at the forefront of a burgeoning field with significant implications for both patients and investors.



Lipoprotein(a), or Lp(a), is a type of lipoprotein that carries cholesterol, fats, and proteins in the blood. Elevated levels of Lp(a) are a well-documented risk factor for atherosclerotic cardiovascular disease, affecting as many as 1 in 5 adults globally. Unlike LDL cholesterol, which is effectively managed by statins, Lp(a) levels remain largely untreated by current standard-of-care therapies. This presents a substantial commercial opportunity for Merck, with approximately 1.4 billion people worldwide having elevated levels of Lp(a).

The acquisition of HRS-5346 aligns with Merck's existing cardiovascular portfolio by expanding and complementing their cardio-metabolic pipeline. Dr. Dean Y. Li, president of Merck Research Laboratories, stated that "HRS-5346, an investigational oral small molecule inhibitor of Lp(a) formation, is an important addition that expands and complements our cardio-metabolic pipeline." This acquisition targets elevated Lipoprotein(a) (Lp(a)), a well-documented risk factor for atherosclerotic cardiovascular disease, affecting as many as 1 in 5 adults globally. By addressing this risk factor, Merck can offer patients an additional option to reduce their risk of atherosclerosis, which is a significant strategic advantage.

Strategically, the acquisition of HRS-5346 provides Merck with an oral administration route for Lp(a) inhibition, which could offer competitive advantages over injectable therapies targeting the same pathway. This is particularly important because the oral administration route could significantly impact patient acceptance and adherence if efficacy proves comparable to injectable alternatives. Currently, HRS-5346 is in Phase 2 trials in China, and Merck's global development capabilities will likely accelerate the clinical program, potentially expanding trials to include cardiovascular outcomes endpoints necessary for regulatory approval.

The $1.77 billion milestone structure suggests confidence in both technical and commercial feasibility, though investors should recognize that Phase 2 assets typically have a 30-40% probability of reaching the market. This acquisition wisely expands Merck's cardiometabolic pipeline beyond traditional lipid-lowering approaches, positioning the company to address a residual risk factor that remains largely untreated by current standard-of-care therapies. Unlike statins, which don't significantly impact Lp(a) levels, targeted inhibitors like HRS-5346 could address this residual risk factor, providing a more comprehensive approach to cardiovascular disease management.

However, the development and commercialization of HRS-5346, currently in Phase 2 clinical trials, present several potential risks and challenges. One of the primary risks is the uncertainty of regulatory approval. As stated in the forward-looking statement, "There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful." This highlights the significant risk that HRS-5346 may not receive the necessary regulatory approvals to proceed to market.

Another challenge is the clinical development hurdles that HRS-5346 still faces. Phase 2 assets typically have a 30-40% probability of reaching the market, indicating a substantial risk of failure. Merck can mitigate this risk by leveraging its global development capabilities to accelerate the clinical program. This includes potentially expanding trials to include cardiovascular outcomes endpoints necessary for regulatory approval, as mentioned in the materials.

Additionally, the competitive landscape poses a risk. Other Lp(a)-targeting therapies in development primarily use RNA-based mechanisms requiring injection, which differentiates HRS-5346 as an oral small molecule approach. However, the success of these competing therapies could impact the market potential for HRS-5346. Merck can mitigate this risk by emphasizing the potential advantages of an oral administration route, which could significantly impact patient acceptance and adherence if efficacy proves comparable to injectable alternatives.

Furthermore, the financial implications of the deal present a risk. Merck expects to record a pre-tax charge of $200 million, or approximately $0.06 per share, to be included in GAAP and non-GAAP results in the quarter the transaction closes. While this charge is minimal relative to Merck's $238 billion market cap, it still represents a financial risk. Merck can mitigate this risk by ensuring that the potential milestone payments and royalties on net sales, if approved, justify the initial investment.

In summary, the potential risks and challenges associated with the development and commercialization of HRS-5346 include regulatory uncertainty, clinical development hurdles, competitive landscape, and financial implications. Merck can mitigate these risks by leveraging its global development capabilities, emphasizing the advantages of an oral administration route, and ensuring that the potential financial returns justify the initial investment.

The acquisition of HRS-5346 represents a bold bet by Merck on the potential of Lp(a) inhibition in cardiovascular disease management. While the risks are significant, the potential rewards are substantial. For patients with elevated Lp(a) levels, HRS-5346 could offer a new option to reduce their risk of atherosclerosis, potentially saving lives and improving quality of life. For investors, the deal represents an opportunity to capitalize on a growing market with significant unmet needs. However, the success of HRS-5346 will ultimately depend on its ability to navigate the complex landscape of clinical development and regulatory approval. Only time will tell if Merck's bet on HRS-5346 will pay off, but one thing is clear: the stakes are high, and the potential impact on cardiovascular care could be transformative.