The world’s bestselling cancer drug is prescribed at a fixed dose regardless of patient weight — a strategy leading oncologists say has no medical basis and is costing health systems billions they cannot afford.
Kehinde Adegoke | ICIJ Cancer Calculus
Every three weeks, cancer patients around the world receive an infusion of Keytruda — the pharmaceutical blockbuster that earned its maker Merck $31.7 billion last year. Whether they weigh 50 kilograms or 100, they all get the same amount: 200 milligrams.
That single decision — to fix the dose regardless of body weight — is costing the global health system an estimated $5 billion over 15 years, according to researchers at the World Health Organisation. In the United States alone, the annual excess runs to $825 million. And leading oncologists say there is no clinical reason for it.
Bishal Gyawali, an oncologist and drug policy researcher at Queen’s University in Canada, is unsparing: “There is no scientific, medical, biological reason to do that. It is just commercially motivated.”
The Commercial Logic
Under weight-based dosing — the standard approach for most medicines — a smaller patient receives a smaller dose. That means fewer vials sold per treatment cycle. Merck’s fixed-dose model eliminates that variable entirely, ensuring the same volume of drug is dispensed to every patient, regardless of size.
Gyawali is direct about what he sees driving that choice: “They can sell more of the drug, and they will make more money.” Merck has never publicly acknowledged a commercial rationale for the fixed dose.
Merck’s Position
“Merck bases its dosing formulas on clinical evidence detailed in the FDA-approved recommended dosage section of its Keytruda prescribing information,” the company said in a statement to ICIJ. It has not changed its guidance.
What the Science Says
A yearlong investigation by the International Consortium of Investigative Journalists and 47 media partners in 37 countries found that clinical trials in India, Singapore, Malaysia and Taiwan have independently reached the same conclusion: lower, weight-adjusted doses of Keytruda produce equivalent outcomes for certain cancer types. The savings are not theoretical — three countries have already acted on the evidence.
The Netherlands, Canada and Israel have already acted on the evidence, switching patients to weight-based dosing. Daniel Goldstein, director of the Centre for Cancer Economics at Rabin Medical Centre in Israel, has spent years documenting the financial distortion. His 2017 analysis put the excess U.S. annual cost at $825 million. The WHO projection covering all eligible lung cancer patients globally through 2040 reinforces his findings.
“The health system just simply cannot afford all of these drugs,” Goldstein told ICIJ. “And in every single country in the world, there is pressure.”
The Evidence Trail
India: Trials at Tata Memorial Hospital in Mumbai tested 50 mg doses every six weeks alongside chemotherapy for breast cancer patients. Results indicate comparable efficacy at a fraction of the standard cost.
Israel: Goldstein’s team calculated that fixed dosing costs the U.S. health system $825 million more per year than weight-based prescribing would, with no corresponding clinical benefit.
WHO: A modelled projection estimated $5 billion in avoidable lung cancer drug spending globally by 2040 if dosing were based on patient weight rather than a fixed 200 mg dose.
Netherlands, Canada, Israel: All three have formally adopted weight-based dosing protocols, reducing per-patient drug expenditure while maintaining clinical outcomes.
The Human Cost
The excess spending is not an abstraction. Every dollar spent on unnecessary drugs is a dollar unavailable for other patients. In India, where a single month of Keytruda can cost more than a year’s wages, the question of dose efficiency is whether a patient receives treatment at all.
In Guatemala, oncologist Julio Ramírez holds authorisation to treat two or three patients with Keytruda at his public hospital in Quetzaltenango. He describes choosing among the many who need it as “playing God.” The fixed global dose, priced at a fixed global premium, arrives at his ward as a rationing problem.
Between 2014 and the end of 2025, Merck generated approximately $163 billion in Keytruda sales. The company returned nearly $75 billion of that to shareholders through dividends and an additional $43 billion through share buybacks.
“The share of R&D costs in relation to the price of a vial is very tiny, and they have long been recouped. The price is thus excessively high — not to cover R&D costs or hedge risks, but to make maximum profits.”
— Patrick Durisch, Public Eye, Switzerland
What Happens Next
Merck’s primary Keytruda patents expire in 2028. The company has filed at least 1,212 patent applications across 53 countries to maintain exclusivity well beyond that date. Cheaper biosimilar versions — which would make the dosing debate less financially consequential — remain years away for most markets.
Until they arrive, health systems that continue to prescribe the fixed 200 mg dose are, in the assessment of the researchers who have studied it most closely, paying for a drug that most of their patients do not need.
