Merck & Co., Inc., known as MSD outside the United States and Canada, built the most commercially successful drug in pharmaceutical history,KEYTRUDA,and the vaccine that may eliminate cervical cancer entirely. In 2023, the company posted $60.1 billion in revenue, employed 72,000 people, and reached more than 550 million patients worldwide.
The arithmetic of KEYTRUDA is difficult to overstate. A single monoclonal antibody, pembrolizumab, generates over $25 billion in annual revenue. It is the best-selling drug on the planet. It has been approved for more cancer indications than any other therapy in the history of medicine. And the story of how it came to exist is a study in institutional patience and the peculiar economics of drug development.
Pembrolizumab is a PD-1 inhibitor. It works by blocking a protein that cancer cells exploit to hide from the immune system. The mechanism itself was not MSD’s discovery. The foundational science of immune checkpoint inhibition emerged from academic laboratories, and multiple companies pursued the same target. What separated MSD was execution: the speed of clinical development, the breadth of the trial programme, and the willingness to run studies across dozens of tumour types simultaneously. Most oncology drugs are approved for one or two indications and then slowly expand. KEYTRUDA launched into melanoma and then moved into lung cancer, bladder cancer, head and neck cancer, renal cell carcinoma, Hodgkin lymphoma, gastric cancer, cervical cancer, hepatocellular carcinoma, and a growing list that now exceeds 40 approved indications globally.
That expansion was not merely a commercial strategy. Each new indication required a separate set of clinical trials, each with its own patient populations, endpoints, and regulatory submissions. The investment required to sustain that programme across two decades runs into the tens of billions of dollars. KEYTRUDA is not simply a product. It is a platform, and the platform has become the financial foundation of a $60 billion company. In 2023, pembrolizumab accounted for more than 40 per cent of MSD’s total revenue. No other pharmaceutical company in the world depends so heavily on a single molecule.
There is a reasonable argument that Gardasil, not KEYTRUDA, will prove to be MSD’s most consequential product. KEYTRUDA treats cancer. Gardasil prevents it. That distinction matters over decades.
Human papillomavirus causes virtually all cervical cancer, a disease that kills more than 340,000 women annually, the overwhelming majority of them in low- and middle-income countries. MSD developed the first HPV vaccine and brought it to market in 2006. Gardasil 9, the current formulation, protects against nine HPV types responsible for approximately 90 per cent of cervical cancers. In countries with high vaccination coverage, cervical cancer incidence has already begun to fall. Australia, which achieved early and broad uptake, is on track to functionally eliminate cervical cancer as a public health concern within a generation.
The vaccine works. The epidemiological evidence is unambiguous. What remains is coverage. The World Health Organization has set a target of vaccinating 90 per cent of girls by age fifteen globally by 2030. That target will not be met, but the trajectory is in the right direction. MSD has committed to supplying Gardasil to Gavi, the Vaccine Alliance, at reduced prices for the world’s lowest-income countries, and the company’s India operations have made Gardasil available through private channels. The prospect of eliminating an entire category of cancer through vaccination is, by any measure, one of the most significant public health interventions of the twenty-first century.
MSD holds the fifth-largest patent portfolio among OPPI member companies at the Indian Patent Office. Between 1997 and 2026, the company filed 1,456 patent applications in India and secured 130 grants. The portfolio is concentrated in two areas that mirror the company’s global identity: immuno-oncology and vaccines.
The filing pattern tells a specific story. The early applications, in the late 1990s and early 2000s, centred on small-molecule compounds for cardiovascular disease, diabetes, and infectious disease. Januvia (sitagliptin), MSD’s DPP-4 inhibitor for type 2 diabetes, generated a cluster of composition-of-matter and formulation patents during this period. As the company’s research priorities shifted toward biologics and immuno-oncology in the 2010s, the Indian filing strategy followed. KEYTRUDA-related patents, covering pembrolizumab itself, combination regimens, biomarker-selected treatment protocols, and manufacturing processes, now form a significant portion of MSD’s active Indian portfolio.
India’s patent regime, shaped by Section 3(d) of the Indian Patents Act, applies a stricter standard of novelty than many other jurisdictions. The 130 grants from 1,456 filings reflect that reality. It is a grant rate consistent with other large multinational filers in India, where the patent office routinely examines claims for incremental innovation more rigorously than its counterparts in the United States or Europe. MSD India, listed as an OPPI member, maintains a filing programme scaled to a company that generates $60 billion in global revenue and holds foundational intellectual property in the world’s most valuable oncology franchise.
In 2023, MSD’s medicines and vaccines reached more than 550 million people worldwide, up from 500 million the prior year. The number is large enough to be abstract, so it is worth understanding what it includes.
The most striking component is the Mectizan Donation Program. Since 1987, MSD has donated Mectizan (ivermectin) to treat river blindness (onchocerciasis) in sub-Saharan Africa and Latin America. It is the longest-running disease-specific drug donation programme in pharmaceutical history. The company committed to providing the drug free of charge for as long as needed, to as many as needed. That pledge has now lasted nearly four decades. Hundreds of millions of treatments have been distributed. River blindness, which once blinded entire communities along West African rivers, has been eliminated as a public health threat in several countries. The programme later expanded to include lymphatic filariasis. MSD does not sell Mectizan. It gives it away. The decision, made by then-CEO Roy Vagelos in 1987, is one of the most studied cases in pharmaceutical ethics and remains unusual in its scope and duration.
Beyond Mectizan, MSD’s access programmes span tiered pricing for Gardasil in Gavi-eligible countries, licensing agreements that allow generic manufacturers to produce certain MSD products for low-income markets, and direct distribution of KEYTRUDA through oncology access programmes in emerging economies. The company’s 2022–2023 and 2023–2024 Impact Reports document these efforts in detail, including specific data on India and other emerging markets where MSD India operates as an OPPI member.
In 2022, MSD employed 69,000 people and generated $59.3 billion in revenue. By 2023, the workforce had grown to 72,000 and revenue reached $60.1 billion. The growth is almost entirely attributable to KEYTRUDA’s continued expansion across new indications and geographies. The company’s workforce growth of 3,000 people in a single year reflects the clinical, regulatory, and commercial infrastructure required to sustain the world’s largest oncology franchise.
Sources: MSD Impact Reports 2022–2023 and 2023–2024. Indian Patent Office (patent filing data, filtered for Merck & Co. excluding Merck KGaA). OPPI member directory.