'Phase 0' Trials Aim to Speed Cancer Drug Development
Report on first such study involves effort to improve chemotherapy effectiveness
FRIDAY, April 17, 2009 (HealthDay News) -- Even after years of painstaking research and testing, only a small percentage of cancer agents make it from the laboratory to the patient. So scientists have come up with a way to weed out the duds earlier in the process and speed good medications to the marketplace.
The new model, a so-called "phase 0" clinical trial, promises to streamline the costly and time-consuming drug development process, helping to deliver good drugs to people who need them more quickly.
"We want to find out if they're ineffective in the smallest number of patients and get definitive information as early in the development process as possible," said Dr. James H. Doroshow, director of the division of cancer treatment and diagnosis at the National Cancer Institute in Bethesda, Md.
As the name implies, a phase 0 trial precedes "phase I" testing, traditionally the first step in the process of human drug testing. In a phase I study, the goal is to determine the best way to administer a drug and the maximum dose tolerated with the fewest side effects.
Phase 0 studies expose a small number of people to low doses of a drug over a limited period of time -- seven days or less. Scientists look at how the body reacts to the drug and how it acts in the body. If the drug hits its intended target without producing significant side effects, the next phase can be expedited. If not, a decision can be made to scrap the drug before it goes on to further, more costly development and testing.
"It may help accelerate clinical drug development in oncology because you're able to theoretically get the drug into man faster and learn more about the drug in man earlier," explained Dr. Patricia M. LoRusso, director of the phase I clinical-pharmacology team at the Barbara Ann Karmanos Cancer Institute in Detroit.
A mere 5 percent of new oncology drug applications submitted to the U.S. Food and Drug Administration get approved, according to the National Cancer Institute. One reason is the lack of systems to predict early on which drugs would be useful and which would have too many side effects, Doroshow explained. In fact, 70 percent of phase II drugs don't make it to the third phase because of a lack of efficacy.
"We need to have a better handle on whether or not they are going to be useful sooner," he added.
To speed up development, the National Cancer Institute established the NCI Experimental Therapeutics (NExT) program, of which phase 0 trials are an integral part.
The first-ever phase 0 trial involved ABT-888, an oral drug that inhibits an enzyme critical for repairing DNA damage. It's believed that the drug could improve the effectiveness of chemotherapy. Researchers obtained key data within five months of the study's initiation, which helped guide the design of subsequent phase I trials. The findings were published online April 13 in the Journal of Clinical Oncology.
"I think it's going to lay out a very interesting model for other researchers who are also interested in phase 0 studies," said T. Patrick Hill, senior policy fellow at the Edward J. Bloustein School of Planning and Public Policy at Rutgers, and a clinical research ethics consultant at the Cancer Institute of New Jersey, both in New Brunswick.
Experts expect the model to be used for other types of drugs as well.
Phase 0 trials expose people to less toxicity and involve fewer participants -- 10 to 12, on average, versus 20 to 25 in a phase I trial. Trial participants receive only a limited number of doses -- and much lower doses -- over a shorter period of time. However, because small doses of a drug are given for a short period, participants probably will not realize a therapeutic benefit.
So why participate?
"Altruism is an enormously powerful motivator," explained Hill, adding that he believes it will be the force that drives future participation in phase 0 trials. However, he said he sees nothing ethically objectionable about compensating people for reasonable costs they might incur as participants, such as money spent for travel, food and overnight stays.
The National Cancer Institute does not offer cancer patients financial incentives to participate in trials, Doroshow said.
Study participants also need to be aware that phase 0 trials, like any trial, might involve invasive procedures, such as blood work and biopsies. Before enrolling in a study, people should ask how it might negatively impact them and how it would positively impact others, LoRusso said.
"Some people would say 'no' because they don't want to be a guinea pig, but there are people out there who want to advance the science for future patients if they can," she said.
The U.S. National Cancer Institute has more on phase 0 trials.