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Clinical trials are essential to developing new cancer treatments, evaluating safety, establishing effective doses, and determining whether investigational therapies improve patient outcomes. They may also provide patients with access to treatments that are not yet available through standard clinical care.
Despite these benefits, participation remains limited. Fewer than 5% of patients receiving cancer treatment are reportedly enrolled in clinical trials, although more than 70% indicate that they would be willing to participate. Complex and restrictive eligibility criteria are among the factors contributing to this gap.
Eligibility requirements are necessary because researchers must define the population being studied and protect participants from unreasonable risks. However, criteria can become problematic when they are copied from previous protocols without considering the investigational drug, cancer type, treatment mechanism, or accumulated clinical evidence.
The FDA warns that unnecessarily restrictive criteria may slow enrollment, reduce patient access, and produce findings that do not fully represent the treatment’s effects in the population that will ultimately use it. Broader criteria may therefore improve both enrollment and the generalizability of clinical-trial results.
FDA Guidance Targets Three Barriers
The FDA’s Oncology Center of Excellence finalized three separate guidance documents addressing eligibility practices that regularly affect oncology studies.
The documents cover:
- Performance status requirements
- Washout periods and concomitant medications
- Laboratory-value thresholds
These documents form part of a larger FDA series addressing cancer clinical-trial eligibility. Previous guidance has examined the inclusion of patients with brain metastases, organ dysfunction, viral infections, prior malignancies, and other characteristics that historically limited participation.
The latest recommendations are not legally binding regulations. FDA guidance documents describe the agency’s current thinking and allow sponsors to use alternative approaches when those approaches satisfy relevant statutory and regulatory requirements.
Cancer Trial Access and Performance Status
Performance status measures how well a patient can complete ordinary activities and daily tasks. Oncology trials commonly use the Eastern Cooperative Oncology Group scale or the Karnofsky Performance Status scale to determine whether a person is physically capable of participating.
Many trials have traditionally enrolled patients with relatively high functional status while excluding those whose cancer has substantially affected their daily activities. The FDA’s final guidance encourages sponsors to include patients with a wider range of performance status when doing so is clinically and scientifically appropriate.
Cancer Trial Access May Improve Enrollment
Including patients with lower performance status could increase the pool of eligible participants and allow trials to enroll more quickly. It may also improve the external validity of study findings because patients treated in everyday oncology practices frequently have poorer health or greater functional limitations than traditional trial participants.
However, broader enrollment requires careful planning. Patients with lower performance status may experience more adverse events, need additional caregiver assistance, or find travel and study procedures difficult.
Sponsors may need to use decentralized trial elements, remote assessments, transportation support, flexible visits, or alternative study designs to improve retention while protecting participants. The FDA also recommends supplementing conventional performance-status measures with patient-reported outcomes and digital health technologies where appropriate.
Cancer Trial Access Requires Smarter Washouts
A washout period is a treatment-free interval between a patient’s previous cancer therapy and the investigational treatment being evaluated. These periods are intended to allow prior drugs or their effects to decline, reduce overlapping toxicity, and prevent researchers from incorrectly attributing outcomes to the new treatment.
The FDA does not recommend eliminating washout periods entirely. Instead, it encourages sponsors to determine whether a fixed time-based interval is scientifically justified for the specific drug and patient population.
Cancer Trial Access Through Evidence-Based Timing
Where possible, relevant clinical and laboratory parameters should be used instead of automatic time-based restrictions. For example, eligibility may depend on whether a clinically significant adverse effect has resolved or whether a laboratory result has returned to an acceptable level.
When a fixed washout period is necessary, the protocol should explain the rationale and consider the pharmacokinetics and pharmacodynamics of the previous therapy. A washout may remain appropriate when the previous treatment could cause delayed antitumor effects or overlapping toxicity that could affect patient safety or study interpretation.
This approach may be especially important for patients with aggressive or advanced cancer. Requiring a person to remain without treatment for an arbitrary period could allow disease progression and prevent the patient from qualifying for a trial.
Medication Restrictions Need Scientific Support
Cancer patients often take several medications in addition to anticancer treatments. These may include drugs for diabetes, hypertension, infections, pain, nausea, cardiovascular disease, or treatment-related complications.
Broadly excluding patients who use other medications can disproportionately affect older adults and people with multiple chronic conditions. The FDA states that concomitant medication exclusions should be based on clinically relevant drug interactions, overlapping toxicities, or other clearly defined risks.
When an interaction can be managed safely, sponsors may consider modifying the dose or regimen of the investigational treatment or the other medication rather than excluding the patient entirely. Such changes must be justified in the trial protocol and clearly explained to participants and caregivers.
Cancer Trial Access Enters a New Phase
The FDA’s final guidance documents represent an important shift toward more inclusive and scientifically justified oncology research.
By reconsidering performance-status exclusions, replacing arbitrary washout periods, allowing appropriate concomitant medications, and modernizing laboratory requirements, sponsors may be able to enroll patients more quickly and generate evidence that is more relevant to clinical practice.
The success of the guidance will depend on how effectively drug developers, investigators, and institutional review boards incorporate the recommendations into future protocols.
Cancer trial access cannot be improved through eligibility reform alone. Patients also face geographic, financial, informational, transportation, and institutional barriers. Nevertheless, removing unnecessary medical exclusions is a meaningful step toward ensuring that more people can participate in research and that approved treatments are supported by evidence from the populations most likely to use them.
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