Phase 2 studies are designed to provide an estimate of the safety of a drug and its efficacy for a particular indication. A relatively homogenous patient population is typically studied, to minimize the ‘noise’ that would affect interpretation of results.
The evaluation of safety and tolerability provides data on common short-term side effects and risks, and helps to identify the optimal dose for future studies.
Phase 2 clinical trials may also include exploratory analyses of additional study endpoints, target populations, or subsets of infection (e.g. those caused by a particular strain of pathogen or at a particular site in the body).
As with phase 1 trials, a phase 2 trial requires clinical trial authorization (CTA) from a regulatory authority and ethical approval.
International studies: Phase 2 and 3 studies are often multinational. If sites in multiple countries are participating in a phase 2 trial, the study must comply with national regulatory requirements in all countries. Guidance is available from the US FDA and the EMA on planning of multinational trials.
General trial essentials
Trial registration: All studies evaluating a drug in patients must be publicly posted before a trial starts, for example at clinicaltrials.gov or Eudract.
Good Clinical Practice (GCP): To ensure the safety of participants and the reliability of data, all clinical trials must comply with GCP.
Other considerations
Before a clinical trial can be started in patients with pneumonia (whether in phase 2 or phase 3), a phase 1 study must be carried out to evaluate the lung penetration of a test drug in healthy subjects, to ensure an adequate drug concentration is achieved in epithelial lining fluid (ELF), the site of infection.