Keytruda (pembrolizumab) costs roughly $10,000 per infusion before insurance, making it one of the most expensive cancer treatments on the market. A single 100-mg vial runs about $4,300, and most adults need two vials per dose. What you actually pay depends on your insurance, your treatment schedule, and whether you qualify for financial assistance.
The List Price Per Dose
Each 100-mg vial of Keytruda is priced at approximately $4,316. The standard adult dose is 200 mg given every three weeks, which means two vials per infusion and a drug cost of roughly $9,970 per dose. The FDA also approved an alternative schedule of 400 mg every six weeks, which uses four vials but spaces out visits. Either way, the annual drug cost alone lands in the range of $170,000 to $175,000 for a full year of treatment.
On top of the drug itself, your clinic or hospital charges a separate fee to administer the infusion. The national median for an initial IV infusion session is about $536 at commercial rates, though this varies widely by facility. Hospitals at the higher end charge more than twice what lower-cost facilities charge for the same service. That administration fee gets added to every single infusion visit.
What You Pay With Medicare
Keytruda is given by IV in a clinic or hospital, so it falls under Medicare Part B rather than Part D. After you meet your annual Part B deductible, you’re responsible for 20% coinsurance on each infusion. With the drug and administration costs combined, that 20% adds up quickly.
For someone on Original Medicare with no supplemental coverage, the typical out-of-pocket cost runs between $1,300 and $2,100 per infusion, according to the drug’s manufacturer. On an every-three-week schedule, that translates to roughly $22,000 to $36,000 per year in coinsurance alone. A Medigap (supplemental) plan can cover some or all of that 20%, significantly reducing what comes out of your pocket.
What You Pay With Private Insurance
If you have employer-sponsored or marketplace insurance, your share depends on your plan’s structure: copays, coinsurance percentages, and most importantly, your annual out-of-pocket maximum. Most commercial plans cap total yearly spending somewhere between $3,000 and $9,000 for an individual. Once you hit that ceiling, your plan covers 100% of the remaining costs for the year. Because Keytruda is so expensive, many patients reach their out-of-pocket max within the first few infusions.
Before coverage kicks in fully, though, you may owe a percentage of each infusion. A plan with 20% coinsurance on specialty drugs could leave you owing close to $2,000 per dose until you reach your cap. Prior authorization is almost always required, so expect your oncologist’s office to handle paperwork with your insurer before treatment begins.
Financial Assistance Programs
Merck, the company that makes Keytruda, runs two main programs to help with costs. The first is a copay assistance program for people with commercial (private) insurance. This card reduces your per-infusion copay, sometimes to $0, up to a set annual benefit limit. It is not available to patients on Medicare, Medicaid, or other government-funded insurance.
The second is the Merck Patient Assistance Program, designed for people who are uninsured or underinsured. To qualify, you must be a U.S. resident with a prescription from a U.S.-licensed provider. The program has income-based eligibility criteria, and people who don’t meet the standard thresholds can still apply by documenting financial and medical hardship. Patients accepted into this program may receive Keytruda at no cost.
Beyond Merck’s own programs, independent nonprofit foundations sometimes offer grants to help cancer patients cover treatment costs. Your oncology team’s financial counselor can typically identify which foundations are currently accepting applications for your cancer type.
How Treatment Length Affects Total Cost
Keytruda isn’t a one-time treatment. Depending on the type and stage of cancer, treatment can last anywhere from a few months to two full years. For many advanced cancers, the standard course runs up to 24 months as long as the cancer responds and side effects remain manageable. Some patients on adjuvant therapy (treatment after surgery to reduce recurrence risk) receive it for about 12 months.
On the every-three-week schedule, a full year means roughly 17 infusions. Two years means around 35. On the every-six-week schedule, those numbers drop to about 9 and 18 respectively. The total cost before insurance for a two-year course can exceed $350,000 in drug costs alone, not counting administration fees, lab work, or imaging scans used to monitor your response.
Why Costs Vary So Much
Several factors create a wide range in what patients actually pay. The type of facility matters: hospital outpatient departments generally charge higher administration fees than independent infusion centers. Geography plays a role too, with prices varying significantly across regions. Your weight used to matter as well, since Keytruda was originally dosed by body weight at 2 mg per kilogram. The current flat-dose approach (200 mg or 400 mg) simplified things, but some treatment protocols for specific cancers may still involve weight-based dosing combined with other drugs, adding to overall costs.
Insurance plan design creates the biggest variation in personal cost. Two people receiving identical treatment can pay vastly different amounts depending on their deductible, coinsurance rate, out-of-pocket maximum, and whether they have secondary coverage. If you’re facing Keytruda treatment, asking your oncology center’s billing or financial counseling team for a personalized cost estimate based on your specific plan is the most reliable way to understand what you’ll owe.