FDA Eases Cancer Trial Eligibility Requirements: No More One-Size-Fits-All Rules for Performance Status, Laboratory Values, and Washout Periods

Eligibility criteria for cancer clinical trials are often far narrower than the patient population seen in everyday clinical practice. In July 2026, the US Food and Drug Administration’s (FDA) Oncology Center of Excellence released three final guidances addressing performance status, laboratory values, and washout periods and concomitant medications, respectively, with the aim of reducing barriers that lack a scientific basis and giving more patients an opportunity to participate in research.

The three documents finalize drafts published in April 2024. The central principle is not to eliminate safeguards across the board, but to require trial sponsors to explain the rationale for each exclusion criterion. Restrictions should be proportionate to the characteristics of the disease, the action of the investigational therapy, and its known risks, rather than relying on standardized language applied to all patients and drugs.

Regarding performance status, the FDA recommends enrolling a broader range of patients instead of routinely excluding those with poorer functional capacity. Such changes could make study results more reflective of clinical practice and may also affect participant retention and the required sample size. Broadening eligibility therefore still needs to be planned alongside statistical design, care requirements, and safety monitoring.

The guidance on laboratory values focuses on common thresholds such as blood cell counts and liver and kidney function. The FDA believes patients should be excluded based on abnormal values only when those abnormalities could genuinely increase treatment risks or interfere with the interpretation of results. The guidance also notes that so-called normal values may be affected by population characteristics and testing methods. Applying a single cutoff directly could exclude certain groups without sufficient justification.

Another guidance reexamines washout periods and restrictions on concomitant medications. Whether patients must wait a fixed number of days before enrolling in a trial, or may continue using other medications, should be determined based on the duration of the previous therapy’s effects, recovery from toxicity, and the risk of interactions. This means trial protocols cannot merely include broad, blanket prohibitions; they must provide a scientific rationale at the disease and drug level.

The three guidances reflect the FDA’s current regulatory thinking but are nonbinding recommendations and do not guarantee that enrollment in every cancer trial will expand immediately. Their actual impact will still depend on how sponsors revise protocols, how research institutions and ethics reviews implement them, and the safety and retention data accumulated after eligibility criteria are broadened. If implemented while keeping risks under control, more representative participant populations will help physicians assess the range of patients for whom new therapies are applicable in the real world.