LONDON (Reuters) - Elan and Wyeth's key new drug bapineuzumab worked for a substantial proportion of Alzheimer's disease patients in an intermediate clinical trial, supporting a prior decision to start final phase III tests. The two companies said on Tuesday that although the drug did not achieve overall statistically significant results in the phase II study, its benefits over placebo were significant in an important subgroup. The update on the antibody medicine, also known as AAB-001, is perhaps the year's most keenly awaited biotech trial result. If successful in final-stage trials, the medicine could be the world's first drug to...