Clinical approval success rates for investigational cancer drugs.

We examined development risks for new cancer drugs. For the full study period, the estimated clinical approval success rate for cancer compounds was 13.4% (9.9% for the first half of the study period, 19.8% for the second half). Small molecules had a somewhat higher clinical approval success rate than did large molecules (14.3 vs. 11.5%). Compounds studied solely in hematologic indications had markedly higher estimated clinical approval success rates than did compounds studied only in solid tumor indications (36.0 vs. 9.8%). The first, second, and third cancer indications pursued had estimated clinical approval success rates of 9.0, 8.2, and 6.9%, respectively. Success rates of second and third indications were found to be highly dependent on the success or failure of the first indication pursued (54.9 and 42.4%, respectively, for second and third indications if the first indication is a success, but 2.5 and 1.8%, respectively, if the first indication is a failure).