Which statement best describes the difference between a hit and a lead?

Which statement best describes the difference between a hit and a lead?

• A. A hit is an initial active compound identified by screening; a lead is a compound that has shown promise after further testing and characterization.
• B. A hit is a marketed drug; a lead is an experimental compound with poor PK.
• C. A hit is always safe; a lead is not.
• D. A hit is a natural product; a lead is synthetic.

Answer: (A)

The main idea here is the progression from an initial active finding to a more developed drug candidate. A hit is an initial active compound discovered in a screening assay showing activity against the target. It confirms that the compound can affect the target, but its potency, selectivity, and drug-like properties are often rough or borderline, so it isn’t ready to be a drug. A lead, on the other hand, has shown more than just activity: after additional testing and characterization, it demonstrates enough promise in areas like potency, specificity for the target, and early drug-like properties (such as absorption, distribution, metabolism, and safety profiles) to justify optimization. Lead optimization then refines these qualities through medicinal chemistry to improve potency and developability toward a potential candidate. So, the best description is that a hit is an initial active compound from screening, while a lead is a compound that has shown promise after further testing and characterization. The other statements mix up who the compound is (e.g., a marketed drug or a natural product) or imply safety guarantees or poor PK by definition, which isn’t how hits and leads are defined.

The main idea here is the progression from an initial active finding to a more developed drug candidate. A hit is an initial active compound discovered in a screening assay showing activity against the target. It confirms that the compound can affect the target, but its potency, selectivity, and drug-like properties are often rough or borderline, so it isn’t ready to be a drug. A lead, on the other hand, has shown more than just activity: after additional testing and characterization, it demonstrates enough promise in areas like potency, specificity for the target, and early drug-like properties (such as absorption, distribution, metabolism, and safety profiles) to justify optimization. Lead optimization then refines these qualities through medicinal chemistry to improve potency and developability toward a potential candidate. So, the best description is that a hit is an initial active compound from screening, while a lead is a compound that has shown promise after further testing and characterization. The other statements mix up who the compound is (e.g., a marketed drug or a natural product) or imply safety guarantees or poor PK by definition, which isn’t how hits and leads are defined.