SAN FRANCISCO – Data on the cost and efficiency of clinical trials are downright depressing. The ratio of dollars invested in R&D to the return on investment has declined about threefold over the past 15 years, according to a study by McKinsey & Co. cited by Lawrence Klein, an associate partner at the consulting firm, who led a lively discussion at the BIO Investor Forum examining methods and tools that could lower costs while speeding drug development.