In the early-stage trial, 77% of 31 evaluable patients receiving the 50-milligram dose experienced a PSA decline of at least 50%, while 48% recorded reductions of 90% or more. Oct 24 (Reuters) - Johnson & Johnson on Saturday said its experimental once-daily oral prostate cancer drug caused tumors to disappear or shrink in an early-stage trial. Johnson & Johnson shares early trial data for its new prostate cancer drug, JNJ-6143.