In early August 2018, the Food and Drug Administration (“FDA”) announced the availability for guidance in Clinical Research projects relating to expansion cohorts used in first-in-human (“FIH”) clinical trials that are used to expedite the development of Oncology Drugs and Biologics. The guidance is directed towards clinical sponsors in their design and conduct of FIH clinical trials intended to expedite the development of cancer drugs, including biological products that use multiple expansion cohort study designs. These studies typically employ multiple, concurrently accruing, patient cohorts, which use individual cohorts that assess the different aspects of the safety, pharmacokinetics, and antitumor activity of the drug. The FDA provides guidance for (1) the characteristics of drug product best suited for consideration for development under a multiple cohort study; (2) information to include in investigational new drug application submissions to justify the design of multiple expansion cohorts; (3) when to interact with FDA on planning and conduct of multiple expansion cohort studies; and (4) safeguards to protect patients enrolled in FIH expansion cohort studies.