Clinical trials are research studies that test a new drug or therapy in patients who have a disease. These studies are classified as phase I, II, or III depending on their purpose.
- Phase I: These initial, small studies test promising new drugs that effectively kill cancer cells in laboratory experiments. The goal is to understand the safe dose and capture early evidence of benefit. Phase I trials may be open to patients with any type of cancer, or only certain types of cancers more likely to respond to specific drugs. Generally, fewer than 50 patients are enrolled.
- Phase II: Once a phase I trial identifies a safe dose, a phase II trial is done to better understand the potential benefit and side effects of the drug. Generally, these studies enroll fewer than 100 patients.
- Phase III: If the new treatment has promising activity in the phase II trial, the next step is usually a phase III trial comparing it with an existing standard treatment. If there is no standard treatment, patients may be randomly assigned to receive either the new treatment or a placebo (such as a sugar pill). Generally, phase III trials are large. The researchers may enroll many hundreds of patients, or even more than 1,000, to establish whether the new treatment is an advance over standard treatment and warrants US FDA approval. Many immunotherapy drugs have been approved in recent years to treat different cancers based on phase III trials showing improved survival compared with previous standards of treatment. A few examples are pembrolizumab (Keytruda) for metastatic bladder cancer, and ipilimumab (Yervoy) combined with nivolumab (Opdivo) for kidney cancer and melanoma.
Why are clinical trials so important?
Often, compounds that work against cancer cells in a laboratory fail in clinical trials. Sometimes, even promising benefits that a new drug exhibits during phase II trials are misleading. A phase III trial is necessary to confirm the benefits. It’s also possible that patients who come to major academic medical centers where phase I and II clinical trials are often conducted might have better outcomes than a broader population of patients.
Why join a clinical trial?
The drugs that help many people living with cancer today became available only after confirmation of their efficacy and safety in patients who chose to enroll in clinical trials. Unfortunately, most commercially available treatments cannot cure metastatic cancer. Clinical trials offer hope and the possibility of improving outcomes for individual cancer patients, and perhaps many others. Information from studies with diverse populations is important when developing new treatments. Yet only one in 10 people participating in clinical trials is Black, Hispanic or Latino, Asian, or from another underrepresented group, according to the National Institute of Minority Health and Health Disparities, which is working to improve access to trials.
If you do choose to join a clinical trial, you retain the right to revoke your consent for any reason.
Are there possible disadvantages to joining a trial?
One troubling issue is the prospect of receiving a placebo, which may be an oral tablet or an intravenous infusion. Some, but not all, phase III trials compare a new treatment to placebo. Depending on the number of groups being compared, the chance of receiving a placebo may be I in 2, 1 in 3, or even less. Patients randomized to placebo are monitored with the same standard of care and may receive another drug if their cancer grows.
The new drug being tested may have unforeseen side effects. Clinical trials, especially phase I and II trials, can also have more intensive clinic visit schedules and require extra blood draws and biopsy procedures.
If the type of cancer you have might be curable, or can be controlled for a prolonged period using an existing, effective standard treatment, it may make sense to try the standard treatment before enrolling in a clinical trial.
How can you find appropriate clinical trials?
Start by talking to your cancer care team. Given recent advances in immunotherapy and targeted therapy, the number of these trials is particularly large, though often confusing to navigate.
Different cancer centers may offer different menus of clinical trials. Eligibility criteria also may affect your options. Some trials require patients with "measurable" tumors because shrinkage of cancer is difficult to measure without a minimum size. Other trials are not open to people taking certain medicines for other health conditions due to the risk for interactions.
You can also learn about appropriate trials by contacting National Cancer Institute-designated cancer centers, or by searching the National Cancer Institute clinical trials website (or calling 800-422-6237 for help).
Who pays for a clinical trial?
It’s wise to ask about costs. Generally, a pharmaceutical company or another funding agency covers the costs of the research drug, and procedures such as biopsies, lab tests, and genetic testing. Health insurance usually covers standard care, such as commercially approved treatments, monthly clinic visits, routine laboratory tests, periodic radiographic imaging, and hospital admissions for urgent problems.
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