Keytruda biosimilar 2028: hospitals need a plan now

The first pembrolizumab biosimilar reaches the FDA queue

Formycon AG and partner Zydus confirmed in recent weeks that FYB206, their pembrolizumab candidate, has been accepted for review by the US Food and Drug Administration. The companies describe it as the first publicly announced Keytruda biosimilar to reach that stage, a careful phrasing that matters: several other developers are known to have pembrolizumab programs in the clinic, but none have publicly confirmed a filing.

That qualifier shapes the planning picture. Acceptance for review is not approval, and a single filed candidate does not produce the price erosion that four or five competing biosimilars eventually deliver. What it does establish is a visible regulatory clock. US patent expiry for pembrolizumab has been widely reported as 2028, and leaders should confirm the specific date against Merck's own filings before putting it in a board deck. The direction of travel, however, is no longer in dispute.

If conversion happens before competition, hospitals get the operational disruption without the price relief.

Subcutaneous conversion is the defensive move already in motion

Merck is not waiting. The company has begun launching subcutaneous Keytruda outside the United States, including in South Korea, according to tracking by Pearce IP. Subcutaneous conversion is the recognized originator playbook ahead of loss of exclusivity: move the installed patient base onto a differently formulated, separately protected product, and the arriving intravenous biosimilar inherits a smaller market than the headline revenue suggests.

For health systems, this is the scenario that deserves the most attention, because it is the one where disruption and savings arrive separately. A hospital can absorb the full operational cost of converting an oncology population to a new administration route and still never capture the acquisition-cost relief it had penciled in for 2028 and 2029. The sequence matters as much as the substance.

Why this is a hospital finance story, not a pharma story

Infused pembrolizumab is a buy-and-bill anchor for hospital outpatient oncology. It drives infusion suite utilization, it sits near the top of Medicare Part B drug spending, and for covered entities it is a meaningful contributor to 340B spread. Leaders should pull their own figures from Merck's SEC filings and the CMS Part B drug spending dashboard rather than relying on secondhand totals, but few oncology service lines will need convincing that this single molecule carries disproportionate financial weight.

A subcutaneous formulation changes three things at once. It changes the billing unit and the reimbursement arithmetic. It changes chair time, freeing infusion capacity that then has to be refilled with other revenue-generating activity or absorbed as idle cost. And it potentially changes site of care, since a short subcutaneous injection is far easier to move to a physician office, an infusion center, or eventually a lower-cost setting that payers prefer.

A biosimilar wave changes something different: acquisition cost. Those two forces do not necessarily arrive together, and they do not necessarily benefit the same part of the organization. Pharmacy may book a win on drug spend while the outpatient service line absorbs a volume and margin hit.

Tariffs and pricing deals are reshaping the baseline

None of this is happening in a stable policy environment. Section 232 tariffs on patented pharmaceuticals and active pharmaceutical ingredients took effect this month with carveouts, according to client guidance from WilmerHale and other firms tracking the Federal Register proclamation. Separately, Fierce Pharma has documented a string of drug pricing arrangements struck between major manufacturers and the administration.

For contracting teams, the practical effect is that the cost baseline against which biosimilar savings will be measured is itself moving. Supply chain exposure for biosimilar developers, many of whom manufacture outside the United States, is a live variable in how quickly and how deeply pembrolizumab prices fall. Any 2028 savings model built on historical biosimilar discount curves should carry an explicit tariff sensitivity.

What oncology leaders should model before 2027

The useful exercise is a two-path scenario plan, built now rather than after an approval decision. Path one assumes meaningful intravenous biosimilar competition from 2028 with the patient base still largely on infusion. Path two assumes substantial subcutaneous conversion first, with biosimilars entering a shrunken intravenous market. Model outpatient margin, infusion capacity, 340B contribution and payer policy under both.

Ownership needs to be assigned. Pharmacy and therapeutics committees will decide formulary posture on a subcutaneous product and, later, on biosimilar interchangeability. GPO and direct contracting teams need to understand what commitments they are signing in 2027 that could lock out 2028 pricing. Payer relations should expect site-of-care steering proposals to follow the subcutaneous launch closely. And CFOs should be told plainly that the downside case is operational disruption without price relief.

The cheapest work available right now is informational: confirm the exact patent and exclusivity dates from primary filings, quantify current pembrolizumab volume and contribution by site of care, and identify which contracts expire inside the window. That costs nothing and makes every subsequent decision faster.