Preclinical Testing Before testing a new medicine in humans, researchers conduct extensive preclinical testing of the molecule. They perform various experiments with in vitro (i.e. in the petri dishes, vials and beakers of the laboratory) or in vivo models. They examine the activity of the potential drug carefully and under many different conditions before moving it into human testing in medical clinics.
Phase I Phase I clinical trials are principally designed to examine the safety of a drug. Further trials and development cannot take place unless Phase I trials show the drug to be reasonably safe when administered to humans. (Some side effects may be acceptable in relation to the severity of the disease targeted.) Participants in this trial are closely scrutinized for the smallest indication of harm caused by the medicine. Because safety is as yet a question, these trials are necessarily small in scope. But they also give researchers an opportunity to begin to understand how the drug will work in humans.
Phase II Phase II clinical trials are designed to further assess safety and evaluate efficacy in humans over the short term, and help set up parameters (e.g. dosage) of the longer-term Phase III trials. Phase II trials are typically placebo-controlled and double-blinded: neither the patient nor the medical personnel know whether the patient is receiving the drug or a placebo. These trials are larger in scope than Phase I and tend to take more time.
In an effort to save time and money, some companies try to minimize the size and scope of Phase II trials. But, recognizing that a short cut can be the longest route, Genentech relies on information from preclinical and Phase I trials to design comprehensive Phase II trials that can clearly demonstrate the efficacy (or lack thereof) of a drug before a Phase III trial. This approach minimizes the risk of unpleasant surprises following the far more expensive Phase III trials.
Phase III Phase III trials are designed to prove the efficacy and confirm the safety of the drug. They are usually double-blinded and placebo-controlled and can involve hundreds or even thousands of patients over many months or even years. Though the numbers of patients involved can be great, the risks are relatively minimal because of the earlier testing to establish safety. The large scope of these trials gives researchers opportunity to prove efficacy and overall safety of the medicine as well as to identify rare side effects of treatment, if any.
Awaiting Regulatory Approval Once all phases of clinical testing have been completed, if the data warrants it, Genentech applies to the Food and Drug Administration for regulatory approval to market the medicine in the United States. If the FDA agrees that the data proves the safety and efficacy of the drug, approval may come in several months or years, with those medicines with the most urgent medical need typically approved more quickly. Genentech works closely with regulatory agencies at all stages of clinical development to help ensure it can provide needed data to obtain approval as quickly as possible.