Final answer:
In phase II clinical trials, endpoints that are overly complex, not directly linked to the drug's primary effect, or that require long-term data, are avoided in favor of those that provide clear evidence of efficacy and safety.
Step-by-step explanation:
In the context of phase II clinical trials, certain types of endpoints are typically avoided. This is because phase II studies are designed to assess the dose/response relationship and establish effective doses for the subsequent phase III trials. The ideal endpoints for phase II trials should provide clear evidence of a drug's efficacy and safety profile without requiring the large patient numbers that phase III trials involve. Thus, endpoints that are overly complex, not directly related to the primary therapeutic effect of the drug, or require long periods to obtain conclusive data are generally not preferred. In phase II, the focus is on gaining preliminary evidence of efficacy, pharmacokinetics, and safety based on which decisions can be made to progress the drug to phase III trials where more definitive endpoints can be studied in a larger, more diverse population.