How Argentina created a cheaper version of a top cancer drug. Can others follow?

In the global fight against cancer, Argentina has emerged as an unexpected testing ground for a high-stakes battle over drug prices — one that is now drawing international attention. At the center of the dispute is pembrolizumab, an immunotherapy widely regarded as one of the most advanced cancer treatments available today.  Marketed globally by United States pharmaceutical giant Merck & Co. (known as MSD outside the U.S. and Canada) under the brand name Keytruda, the drug has transformed outcomes for patients with cancers ranging from melanoma to lung and breast tumors. Shielded behind a plethora of patents, the drug’s price is prohibitive for a majority of individuals. An unlikely legal gap in Argentina, however, opened the door for a local pharmaceutical company to start manufacturing a similar drug at a fraction of the price.  The situation is being closely followed by many actors involved in the field, as the case has become emblematic of a growing global dilemma: how to balance innovation with access. A breakthrough, at a price Pembrolizumab has been hailed as a breakthrough in oncology since its appearance in 2014. Rather than attacking tumors directly, it works by reactivating the patient’s immune system, enabling it to detect and destroy cancer cells. Its clinical impact has been significant. So has its commercial success. Keytruda now accounts for nearly half of Merck/MSD’s global revenues. According to company reports, total sales over the past decade exceeded US$160 billion. Yet the drug’s cost has placed it out of reach for many patients worldwide.  In the U.S. a standard dose of Keytruda — 200 mg, usually taken every 3 weeks —- costs over US$12,000, according to Merck & Co.’s official list price. The price of a full treatment can reach more than US$200,000. An investigation into Keytruda by the International Consortium of Investigative Journalists (ICIJ), which includes some Argentine outlets, found that the cost varies from country to country. Prices can range from US$65,000 in South Africa, US$80,000 in Germany, or US$93,000 in Lebanon, all the way up to US$116,000 in Croatia and US$130,000 in Colombia. This means access is typically limited to those covered by public health systems — the states are the biggest buyers of Keytruda — or private insurance. For health systems already under strain, such costs pose a growing challenge, particularly as cancer incidence continues to rise. A gap in the patent wall The ICIJ investigation revealed that in most major markets, the active ingredient in Keytruda, pembrolizumab, is protected by a dense web of patents that extend Merck/MSD’s market exclusivity.  However, those protections were never secured in Argentina due to stricter standards for pharmaceutical patents put in place during the government of President Cristina Fernández de Kirchner, with the aim of fomenting the production of cheaper versions of drugs. That gap created a rare opportunity. A local pharmaceutical company, Laboratorio Elea — part of the Insud Group — developed a biosimilar version of the drug, known as Pembrox. Biosimilars are not identical copies but are designed to match the original in safety, efficacy, and quality. When Pembrox entered the Argentine market in early 2025, it marked the first such competition for pembrolizumab anywhere in the world. The impact was immediate. Competition changed the equation Within months, the price of Keytruda in Argentina dropped by roughly 50%, as MSD moved to defend its market share. At the same time, access to pembrolizumab expanded dramatically. The national government — the main buyer of the cancer drug, due to its high price —- increased its purchases by more than 1300%, going from 280 doses per year to almost 4,000 in 2025, when Pembrox was released, according to official figures revealed by Infobae and La Nación, two of the local news outlets that took part in the ICIJ investigation. The significant rise in  doses made  a treatment that had once been financially out of reach become more widely available. Today, the price of both drugs is almost the same — US$15,735 per dose of Keytruda and US$15,345 per dose of Pembrox, according to official medicine price lists reviewed by the Herald and converted at the official exchange rate — a figure that remains prohibitively expensive for anyone who must access it privately. Innovation v. access Argentina’s launch of its biosimilar is a rare case that could not be replicated in countries with standard patent regulations. The episode, however, is being watched internationally as a case study in what competition could mean for Keytruda pricing once key patents begin to expire in the U.S. and Europe from 2028 onward.  According to PatSnap, a commercial intellectual property and innovation analytics company, those expirations place “more than US$25 billion in annual revenue directly in the path of biosimilar competition.” The creation of drugs like Pembrox highlights a broader tension at the heart of the pharmaceutical industry.  On one side are companies that argue strong patent protections are essential to recoup massive research and development investments — Merck/MSD says it spent tens of billions of dollars bringing pembrolizumab to market. On the other are governments, patients, and advocacy groups pushing for greater affordability and access, particularly to life-saving treatments for diseases like cancer, which remains one of the leading causes of death worldwide, causing roughly one in six deaths, according to the World Health Organization.  As new therapies become more effective — and more expensive — the question of who gets access is becoming increasingly urgent. The debate has intensified in recent years as drugmakers have increasingly relied on strategies such as “evergreening” — extending patent protection through incremental modifications — to maintain exclusivity. Many see biosimilars and generics as a possible solution, although their adoption also raises complex questions. Argentina, from trailblazer to shutout In the U.S. and Europe, biosimilar versions of pembrolizumab are expected to enter the market once Keytruda’s original patents expire at the end of the decade, potentially introducing the kind of price competition already seen in the South American country.  Analysts say the timing and scale of those price shifts will depend on how many competitors emerge and how quickly health systems adopt them. However, the stakes are high: “No single patent expiry in the history of oncology pharmacology carries a comparable revenue figure, making the Keytruda patent cliff one of the most consequential intellectual property events of the decade,” according to PatSnap. Paradoxically, in Argentina, a recent change in patent policy might mean that another case like that of Pembrox could be unlikely. A decision announced in March by the government of Javier Milei updating patent regulations to eliminate the stricter rules introduced during Kirchnerism is expected to make it easier for pharmaceutical companies — including foreign ones — to secure broader protections, including for complex biologic drugs.  While the move brings the country closer in line with international standards and could open the door to more innovative therapies from abroad, it will also reduce the likelihood of new locally produced generic or biosimilar medicines emerging in the future.