Just 13% of 'positive' phase II studies go forward despite promise
MONDAY, Sept. 10 (HealthDay News) -- Little more than one in eight phase II cancer clinical trials with encouraging results go forward to the larger, phase III stage that's needed to bring a new therapy to patients, a new study finds.
In many cases, the researchers conducting the phase II effort knew beforehand that, due to financial or other constraints, a phase III trial was unlikely.
According to experts, that raises the troubling question of why the phase II study was done at all.
"If all of this effort in supporting phase II trials doesn't go anywhere, it means that the patients included -- and the efforts of their doctors -- could have been spent in finishing potentially practice-changing phase III studies," said the study's lead author, Ian Tannock, professor of medical oncology at Princess Margaret Hospital and the University of Toronto, Canada.
The bench-to-bedside evolution of any new cancer treatment occurs in three stages once a drug clears animal testing. First, a small phase I trial assesses the therapy's safety and calibrates the best dose. Next, a phase II trial (usually less than 100 patients) looks at how effective the therapy might be against a particular type of tumor.
If those results are positive, the drug should next go on to a much larger -- and expensive -- randomized trial comparing the new agent against the current standard of care. Positive results from phase III trials are required for U.S. Food and Drug Administration approval of most new agents.
Given the scarcity of both money and willing volunteers for cancer research, "a phase II trial shouldn't even be started unless there is an intention -- if the phase II results look promising -- to take it forward," said Tannock, who presented the study findings in June at the American Society of Clinical Oncology annual meeting.
All rights reserved