Slowing down to speed up: optimizing country and site selection in atopic dermatitis trials
The atopic dermatitis (AD) clinical trial market is crowded and competitive. Unlike oncology trials, which may span years, dermatology trials are more often a sprint. There is immense pressure on sponsors and CROs to expedite site start-up, first patient in (FPI) milestones, and enrollment above all else.
However, focusing solely on speed can compromise results. Enrolling the wrong patients—such as those with mismatched disease severity or complex comorbidities—can yield high placebo response rates and noisy data, obscuring a drug's efficacy signal. Success in AD trials requires shifting the priority from patient quantity to quality. This starts with expert country and site selection based on historical quality performance, not just enrollment data.
At Parexel, we have completed 69 global AD trials in the past five years, including for a first-in-class biologic approval. We slow down at the beginning of a study to get country and site selection right the first time. This upfront investment enables us to speed up at the end.
Regional standards of care drive strategic country selection
Choosing countries for an AD trial depends on the protocol, sponsor’s timeline and budget, the tested agent, and the target patient group. However, the regional standard of care (SOC) is crucial. For example, as the SOC evolves worldwide, identifying patients who are biologic-naïve is increasingly challenging. Sponsors must select countries where these patients still exist rather than targeting markets saturated with biologics, which often leads to poor enrollment or protocol deviations.
At Parexel, we utilize real-world data to profile patient populations, support protocol development, and refine overall study design. While access to such data is common, interpreting it requires clinical AD expertise. Many trials struggle to enroll enough patients with severe disease. Severe AD is more common in high-income countries, where patients may have access to advanced treatments but also face complex environmental triggers, or in developing regions, where many cases are undertreated due to limited access.
In highly saturated and competitive markets such as the U.S. and Canada, access to biologic-naïve patients is limited. Likewise, in certain European countries, the high standard of care and strict site regulations may hinder recruitment. We often advise sponsors to consider adding Eastern European countries such as Serbia, Slovakia, and Romania to accelerate enrollment of biologic-naïve patients.
Expert site selection expedites study timelines
Every CRO has access to public databases listing top enrolling sites, but quality matters more than quantity. We advise sponsors to focus on fewer, high-performing sites that consistently deliver quality patients and data. It is more efficient to reduce the total site count to concentrate resources on proven contributors.
We rate sites based on four key metrics: AD trial experience, reliability (promised versus enrolled patients), a 1-3 quality rating, and trial activation speed (including average contracting timelines). Our quality rating is derived from internal data on queries, protocol deviations, and screen failures from previous collaborations. This allows us to identify sites that deliver clean, high-quality data, not just high volume. Our dermatology team maintains a comprehensive database that tracks screen failures and patient withdrawal reasons and conducts regular analyses of these data. It's better to avoid a "top enroller" if they have historically produced noisy data that could threaten a study's statistical significance.
We maintain contact with high-performing sites through our Dermatology Sites Network. Understanding the composition and key trigger points of these sites enables us to align study strategies with site expectations. For example, we promote local advertising campaigns rather than insisting on global approaches, due to our knowledge of dermatology sites.
Deep diligence in competition analysis upfront takes time but yields faster qualification and start-up times. To mitigate competitive risks in the crowded AD market, sponsors must assess site-level competition during pre-qualification and engage key Investigators early to secure resources. We recently performed a competitive landscape analysis for a sponsor planning a Phase III AD trial. We found that they would face competition for patients from 115 open and planned Phase I-III/V trials in moderate-to-severe AD, with 26 of them in countries on their list. As a result, we fine-tuned the country and site selection. We leveraged our relationships with key dermatology sites to ensure their study would be the “study of choice” in a crowded environment.
We deliver aggressive FPI timelines by relying on internal teams with experience in running dermatology trials. We recently launched a Phase Ib AD study for a sponsor with a tight budget and timeline. The scope was limited to 12 sites in Bulgaria, Germany, and Poland. Because the budget allowed for only 12 remote qualification visits, we created a concise, high-impact pre-qualification questionnaire to ensure only the most capable sites were targeted. To avoid delays, we negotiated a streamlined confidentiality agreement (CDA) strategy using pre-approved templates. All proposed sites were approved for the trial, and the study met its aggressive startup goals without compromising site quality.
After meeting the FPI timelines, we plan regulatory activities to ensure smooth and continuous enrollment. For example, we recently completed a global Phase II basket trial with sites in the U.S. and Europe. There was a several-month lag between the activation of the U.S. and EU sites. We focused on sites in Georgia to bridge that gap because we knew the trial’s target patient population was well represented there. We assigned a local team to translate trial documents (avoiding notarization delays), used a local customs vendor, and customized processes for Georgian sites—for instance, shipping the study drug upon site activation rather than after the first screening. These strategies allowed us to activate the first Georgian site and achieve FPI just one month after the U.S.
Precision at the start ensures speed at the finish
In AD trials, the fastest way to fail is to rush country and site selection. A study that recruits quickly but produces a high placebo response or poor data quality due to ineligible patients, limited resources, or poor investigator training is a wasted investment. Speed and efficiency come from selecting the right countries for the specific patient profile and partnering with sites known for data integrity.