Scientists at the US National Cancer Institute (NCI) in Bethesda, Maryland, have conducted the first phase 0 oncology trial, which they claim could help accelerate drug development. The NCI phase 0 study tested a single dose of Abbott's small-molecule candidate ABT-888 in 13 patients with advanced cancers. The results, obtained in five months, proved that the drug from the Abbott Park, Illinois, company is well tolerated and inhibits its target—the poly(ADP-ribose) polymerase (PARP) enzyme—in tumor samples and blood cells. In a phase 0 study, a small number of patients is treated with nontoxic microdoses or a single dose of a new drug to obtain pharmacodynamic and pharmacokinetic data. Phase 0 trials can help identify and discard inactive drugs early in the process, ultimately improving success rates. But they are unlikely to become routine in cancer drug development, says Susan Galbraith, vice president oncology discovery medicine and clinical biomarkers at Bristol-Myers Squibb. “There are other approaches that can achieve the same goals faster and for less cost.” Nicola Curtin, professor of experimental therapies at Britain's Northern Institute for Cancer Research (Newcastle), says a phase 0 study can be rolled in with a phase 1 to obtain the same data. For monoclonal antibodies, microdosing may present a challenge. “Traditional antibodies have a 1–2 week half-life so one dose of those drugs would give equivalent exposure to multiple doses of a small-molecule drug,” Galbraith points out.