The search for new therapies usually begins in the laboratory, where ideas for new treatments are tested in cell cultures or animal models. These steps are critical for showing whether a potential treatment has any merit at all. A treatment that fails in the lab is put aside. But one that succeeds there must still be tested in the most important arena of all, the clinical trial.

A clinical trial is the best method researchers have developed to find effective treatments, and, equally important, to weed out useless or harmful treatments. Clinical trials are costly, and may last months. When the treatment being tested proves to not be effective, it can be sorely disappointing. But clinical trials have proven to be the most reliable way, and ultimately the fastest way, to discover treatments that really work.

In fact, there are several types of clinical trials, each of which is important to test both the safety and effectiveness of the new treatment, such as a drug for ALS.

Phase I Trial

The drug is given to a small number of people, either healthy volunteers or people with ALS, to see if it is safe in humans. The numbers are kept small in order to expose as few people as possible to an untried treatment. In fact, by the time a Phase I study begins, researchers have a great deal of confidence that the drug is likely to be quite safe, based on their results from other experiments; nonetheless, the Phase I trial is critical to determine safety. A Phase I trial may also begin to test whether the drug is effective in treating ALS, but this is not its main purpose, and any positive results can only be considered tentative.

Phase II Trial

 A drug that is safe can be initially tested for effectiveness in a Phase II trial. This trial typically enrolls between 30 and 50 people with ALS. Most Phase II trials test the drug against a placebo—an identical pill (or injection, or other form of delivery) that does not contain the drug (this is called a placebo-controlled trial). Neither the researcher nor the ALS patient knows which is which. In this way, their hope of benefit from the real treatment will not affect the results. If the drug continues to appear safe, and shows some signs of effectiveness, it will be tested in the next phase, Phase III.

Phase III Trial

A phase III trial is considered the definitive test of whether a drug is effective. It is always a placebo-controlled trial, and enrolls many more patients than a phase II trial. It is usually conducted by multiple researchers at multiple different sites around the country or even around the world. A treatment that succeeds in a Phase III trial is considered to be truly effective. Once a successful trial is over, the company that manufactures the drug can apply to the United States Food and Drug Administration (FDA) for permission to market the drug for treatment of ALS.

The urgent need for new treatment for ALS can only be met when researchers and people with ALS work together. ALS researchers know that most ALS patients would like to help them develop new treatments. But they also understand the concerns that may make patients and families hesitant to enroll in a trial. Researchers are striving to shorten clinical trials, and make them more convenient for patients and families to take part in.

To learn more about clinical trials, read on about the vital importance of placebo-controlled trials, review clinical trial definitions, and see how you can get involved in a clinical trial in your area.