In a phase I trial, how many sites is ideal?

In the last few posts we’ve been talking about site selection criteria.  We’ve discussed looking for sites that have dedicated phase I oncology teams, private versus academic centers, and how to evaluate a site. The next question: how many sites is ideal?

The nature of the indication can dictate this number. If it’s a rare indication or one that’s not readily diagnosed by the patient’s primary oncologist, you might need 5 to 10 sites to get enough patients to complete your study within a calendar year. If the protocol is fairly standard, we typically prefer to use two sites.

Two sites = tighter control

With two sites, cooperation between the sites is pretty easy. Each site alternates enrolling a patient, making it easy to exercise tight control over data flow, monitoring, and the information sponsors are evaluating to make important decisions such as trial continuation.

While logic dictates that more sites = more patients = faster data collection, it’s not always the reality in phase I oncology trials. Sometimes, a third site (or more) can add complexities that slow down a trial.

"Three’s a crowd"

Surprisingly enough, three sites can be a crowd in a standard phase I oncology trial. Sometimes sites will argue over whose turn it is to enroll a patient. This leads to unproductive complexity, and it’s prevalent enough that some phase I investigators will not conduct a study that involves more than two sites.

Another reason some investigators object to more than two sites is the ethical concern of delaying potentially critical treatments to terminally ill oncology patients because other sites are next in line to enroll patients.

It’s a good idea to match the number of sites to the sponsor’s priorities. If speed is important, remember that using more sites doesn’t always equal faster completion. Sometimes one or two private sites can produce faster results than three or more academic sites.

The decision tree

So to determine the number of sites you need for your next trial, here are the key criteria to evaluate:

  1. If you’re studying a rare cancer type, cast a wider net by engaging multiple sites.
  2. The position of your trial’s investigators on the number of sites needed.
  3. Your timelines and expectations.

If your indication or investigators don’t require a large number of sites, then two sites is often the ideal arrangement since it allows you to retain control while ensuring quality and safety measures are being followed at all times.