Keytruda (pembrolizumab) has a list price of roughly $12,272 per infusion when dosed at 200 mg, based on the wholesale acquisition cost of $6,136 per 100 mg vial. Since most patients receive an infusion every three weeks, that works out to approximately $17,700 per month on average. The actual amount you pay depends heavily on your insurance, where you receive treatment, and whether you qualify for financial assistance.
List Price Per Infusion
Merck, the manufacturer, publishes a wholesale acquisition cost of $6,136 for a single 100 mg vial. The standard dose is 200 mg given every three weeks, which requires two vials per infusion and puts the drug cost alone at $12,272 per visit. Some patients instead receive 400 mg every six weeks, which uses four vials at a cost of $24,544 per visit but spaces treatments further apart, resulting in roughly the same annual spend.
These figures represent the published catalogue price and don’t reflect negotiated discounts that insurers, hospitals, or pharmacy benefit managers may receive. Still, the list price is the starting point for calculating what patients owe.
Total Visit Costs Including Facility Fees
The drug itself is only part of the bill. Each Keytruda visit also includes charges for the infusion service, nursing time, and the facility where treatment takes place. According to the Health Care Cost Institute, the median total price of a single Keytruda visit in a hospital outpatient setting was $21,594 in 2022. In a doctor’s office (non-facility setting), the median was $11,506.
That gap is significant. Hospital outpatient prices ranged from about $10,776 at the low end to over $43,000 at the high end, while office-based visits ranged from roughly $10,500 to $21,400. If you have a choice of where to receive treatment, asking about the site of service can meaningfully affect your total costs. Nearly all Keytruda visits exceeded $10,000 regardless of setting.
What Medicare Patients Pay
Keytruda is administered by a healthcare provider, so for Medicare enrollees it falls under Part B rather than Part D. In traditional Medicare, beneficiaries pay 20% of the approved cost with no annual cap on out-of-pocket spending. For Keytruda specifically, the average annual cost-sharing liability was $9,100, or roughly $760 per month spread across a year of treatment.
That average masks wide variation. Some patients on traditional Medicare faced cost-sharing bills above $5,000 in a single year for Part B drugs, and there’s no built-in limit to protect against higher totals. Medigap (supplemental) policies can cover some or all of that 20% coinsurance, but not every beneficiary carries one.
Medicare Advantage plans also charge up to 20% coinsurance for Part B drugs from in-network providers, but they do cap total out-of-pocket costs. In 2022, in-network caps were set at $7,550 for most plans. Out-of-network coverage is less favorable: nearly half of Medicare Advantage enrollees in PPO-style plans face coinsurance rates above 20% for Part B drugs from out-of-network providers, with some plans charging 40% or even 50%.
What Privately Insured Patients Pay
For people with employer-sponsored or marketplace insurance, out-of-pocket costs depend on your plan’s coinsurance rate, deductible, and out-of-pocket maximum. Most plans apply a percentage-based coinsurance to specialty drugs administered in a medical setting. Even a 10% coinsurance rate on a $12,000+ infusion adds up quickly, but the out-of-pocket maximum (often between $3,000 and $9,000 for individual coverage) limits your total annual exposure.
In practice, many privately insured patients hit their annual out-of-pocket maximum within the first one or two infusions, after which insurance covers the full cost for the rest of the plan year. The financial hit is front-loaded: expect large bills early in treatment, then little to nothing for subsequent infusions that same year. When a new plan year resets, the cycle starts over.
Financial Assistance Options
Merck runs a Patient Assistance Program that provides Keytruda at no cost to eligible patients. To qualify, you generally need to be a U.S. resident, lack insurance coverage for the drug (or have coverage that still leaves the medication unaffordable), and demonstrate that you cannot pay out of pocket. Patients with insurance who face financial hardship may still qualify if they can document special circumstances.
Beyond Merck’s program, several independent nonprofit foundations offer copay assistance for cancer patients on commercial insurance. These grants typically cover a set dollar amount of your coinsurance or copay obligations. Eligibility often depends on your cancer type, income level, and whether funds are currently available, since many programs open and close enrollment as donations fluctuate. Your oncology team’s financial counselor is usually the fastest route to identifying which programs are accepting applications.
It’s worth noting that copay assistance from manufacturers is generally not available to Medicare or Medicaid beneficiaries due to federal anti-kickback rules. Medicare patients may instead qualify for assistance through independent charitable foundations that operate under different legal guidelines.
How Long Treatment Typically Lasts
Keytruda isn’t a one-month prescription. Treatment duration varies by cancer type and how well the drug is working. In many approved uses, patients continue Keytruda for up to two years if the cancer responds and side effects remain manageable. Some patients stop earlier if the disease progresses or if toxicity becomes a concern. Others on certain treatment plans receive it for a defined number of cycles alongside chemotherapy.
A full two-year course at the standard three-week schedule means roughly 35 infusions. At list price, that represents over $400,000 in drug costs alone, not counting facility and administration fees. This is why understanding your insurance benefits and assistance options before starting treatment matters so much.
Biosimilar Competition Is Years Away
Keytruda’s U.S. patents don’t expire until November 2036, meaning biosimilar versions (the biological drug equivalent of generics) are unlikely to reach the American market before then. In Europe, patent protection ends in 2028, so lower-cost alternatives may appear there sooner. For now, there is no cheaper biosimilar alternative available in the U.S., and the pricing landscape is unlikely to shift dramatically in the near term.