US drug companies have increased the number of new clinical trials by more than 50% since 2002, signaling a possible resurgence in R&D productivity, according to a new study by the Tufts Center for the Study of Drug Development (CSDD). The study found that from 2003 to 2005, the rate at which the 10 top-selling US drug companies initiated clinical trials for new drug candidates rose by 52%, following a 21% decline from 1993–1997 to 1998–2002. “This robust improvement could be the start of a break-out from the R&D productivity doldrums that has plagued the major research-based pharmaceutical companies in recent years,” said Tufts CSDD director Kenneth Kaitin. “The real proof will be in the ability of companies to avoid late-stage development terminations and boost overall clinical success rates.” The study also found that: • Of six specific broad therapeutic categories analyzed, oncology/immunologic and CNS had the greatest shares of new drugs entering clinical testing during the 1993–2002 period. • Respiratory, oncology/immunologic and systemic anti-infective drugs had the highest clinical approval success rates for the 1993–2002 period, while gastrointestinal/metabolism, CNS and cardiovascular drugs had the lowest. • Approximately 20% of self-originated new drugs that enter clinical testing received US marketing approval.