How Trials Work

Clinical trials are stringent efforts to determine a treatment’s effectiveness and safety. As a result, there are lots of rules to take bias out of the process. Drug development researchers do not want to mistakenly endorse a drug that is unsafe or ineffective. Alternatively, they do not want to miss one that can help patients.

This video describes the basics of the clinical trial process.


Common Inclusion Criteria

There are requirements a patient must meet before they can enter a clinical trial. Here are several common ones:

• Cancer status
Is the patient newly diagnosed or is their disease progressing? Has the tumor responded to platinum drugs? Does the patient have the specific type of tumor (histology) the drug is being tested against: high grade serous, mucinous, clear cell, endometroid, carcinosarcoma?

• Health
Potential trial participants receive a medical workup, testing blood cell counts, blood chemistry and other factors, to gauge whether they can tolerate the agent being tested.

• Measurable disease
To determine a drug’s effectiveness against the cancer, researchers must measure the tumor response. Some trials use imaging technologies, such as PET/CT, to measure whether a tumor is shrinking. Participants receive a baseline scan to confirm that their tumor is measurable and to record its size before the treatment starts.

• Biopsy
Some trials use biomarkers, such as proteins or gene expression, to determine the drug’s effects in the body. In these cases, clinicians may need a blood sample or tumor tissue to make those measurements.

Common Exclusion Criteria

Drug companies are always concerned that including certain patients in a trial might skew the results. Previous treatments and other factors could make a patient less likely to respond to the drug being tested.

One of the most common exclusion criteria is prior treatments. For some trials, patients are ineligible if they’ve had too many previous treatments or have already received one of the agents being tested as part of a drug combo. 

This is why it is so important to look at clinical trials early. Patients who begin treatment without considering trials may later find they are ineligible for certain trials.

What the “Phases” Mean

Drug testing begins small and grows significantly as the drug gets closer to approval. Early trials are focused on safety and dosage. Later trials seek to demonstrate the treatment’s efficacy.

Phase I
These trials are usually the first time the drug has been tested in humans. Sometimes, they combine two drugs that have already been shown safe and effective when given separately. These are small studies, between 20 and 100 participants, designed to evaluate safety, determine appropriate dosage and identify side effects.

Some phase I trials have two parts: the first is called dose-finding (or dose escalation), in which patients get increasing doses to confirm safety at each dose. The second part is called dose expansion, in which a larger group of patients receive a dose that has already been shown safe in a few patients. During conversations with the trial investigator prior to enrolling in a phase I study, it might be helpful to ask these questions.

Phase II
These are larger studies of 100 to 300 participants that evaluate both safety and efficacy. Sometimes these studies compare the new drug to other treatments.

Phase III
These are much larger studies, 1,000 to 3,000 participants, designed to confirm effectiveness, monitor side effects, compare to other treatments and collect additional information to ensure safe use.

Phase IV
These studies are conducted after the treatment has been approved by the FDA to investigate risks, benefits and optimal use.