11.   Burke explained that sometimes the egg has already implanted, too much time has passed or the drug simply fails.

12.   But even this drug can fail, according to recent reports.

13.   But for an unknown number of other people, the drugs are failing.

14.   But in human testing, the drug failed to live up to the promise.

15.   But, given at a dose that helps patients who have already formed polyps, the drug failed to keep them from developing.

16.   Conventional chemotherapeutic drugs failed to help her, but upon taking Taxol she went into remission and has now been symptom-free for two years.

17.   Conventional drugs failed to slow his rampaging chronic lymphocytic leukemia, or CLL.

18.   Especially in the field of cancer treatment, he said, it is not uncommon for a drug to fail on its first pass through the FDA.

19.   Even when it succeeds in ridding the body of virus, the drug frequently fails to produce a long-term response.

20.   Experts say that in at least half these patients, drugs fail to control seizures.