Bédard PL, et al. - Authors performed this first-in-human study to assess the maximum tolerated dose, safety, pharmacokinetics (PK), pharmacodynamics, and preliminary activity of SAR260301, a potent phosphoinositide 3-kinase (PI3K)β-selective inhibitor. As per results, an acceptable safety profile of SAR260301 was evident, but exposure sufficient to inhibit the PI3K pathway was unachievable because of rapid clearance, and clinical development was terminated. Results thereby highlighted the significance of PK and pharmacodynamic assessments in early drug development.