Phase II - Typically Therapeutic Exploratory
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After the successful completion of Phase I, the experimental medicine is next tested for efficacy (and safety) in Phase II clinical trials. If a significant portion of patients (afflicted with the disease or condition for which the medicine is developed) respond to the treatment, the treatment is judged to work or be ‘active’.
Phase II usually starts with studies in which the primary objective is to explore therapeutic efficacy and safety in patients. Patients are selected by strict selection (inclusion) criteria, leading to a relatively homogenous population, this is done in order to facilitate the interpretation of study results. Phase II studies typically involve:
- Determining the dose(s) and regimen for Phase III trials - often dose finding designs are utilised to give an early estimate of dose response for a pursued indication. Confirmatory dose response studies may be conducted in Phase II or left for Phase III.
- Exploratory analysis of multiple endpoints.
- Exploratory analysis of therapeutic regimens including concomitant medications (medicines which are used at the same time or shortly after another).
- Exploratory analysis of target populations (e.g. mild versus severe disease) for further study in Phase II or III.
The objectives of the Phase II development are:
- To explore therapeutic efficacy (and safety) in patients
- Proof of concept (PoC): to determine the existence of activity or ‘response’ (often using surrogate endpoints) of a new treatment in a particular patient population.
- To determine the dose(s) and regimen (schedule) for Phase III trials
- To explore potential trial endpoints, concomitant medications, and target populations (e.g. age, gender, disease stage/degree), and cumulative effects for subsequent studies, and provide the basis for confirmatory trial design.
The outcomes of PoC should unambiguously be associated with clinical improvement. These outcomes and results must be considered which making a ‘go/no-go’ decision to progress to Phase III development.