Circassia kicks off adaptive-design PhIII grass allergy field trial

Circassia (LON:CIR) has initiated a Phase III trial of its grass allergy immunotherapy. The trial is set to enroll approximately 1,500 patients in a stepwise fashion, an approach Circassia thinks will enable it to use data from the first 400 participants to inform a decision about the overall size of the study.

Oxford, United Kingdom-based Circassia has started to activate trial sites and enroll participants with a view to recruiting approximately 1,500 subjects at more than 100 locations in North America and Europe. Initially, Circassia will give the immunotherapy to 400 participants. If it generates favorable data from this cohort, the research team will decide how big the overall study needs to be to deliver statistically compelling results.

“It allows us to power the study appropriately rather than guessing at the number of subjects that we need now,” Circassia CEO Steve Harris told FierceBiotech. “So you can do the first 400, look at the data and then power the rest of it.”

Circassia is enrolling patients for both stages of the study concurrently, an approach that means it will have participants lined up when it hits go on the second part of the trial. The company is also seeking an idea of how symptomatic the subjects are in the absence of its experimental intervention. One way to do this is simply to ask subjects how they felt in the previous grass allergy season. However, this can cause problems for researchers.

“The data show that there's very little correlation between how they thought they felt and how they actually felt,” Harris said.

Such recall failings can result in people inadvertently exaggerating the severity of their symptoms. To prevent this phenomenon from affecting the composition of the study population, Circassia has built a pretreatment monitoring stage into the trial.

“We are getting patients to record their symptoms in this grass season that's happening right now, making sure they’re sufficiently symptomatic before we look to recruit them into the main part of the study,” Harris said.

Once this grass season is over, Circassia will randomize eligible participants into either the treatment or placebo arm of the clinical trial. Patients in the treatment arm, starting with the 400-person cohort and continuing following the expansion, will receive eight 6-nmol doses of Circassia’s grass allergy immunotherapy over 14 weeks. Circassia expects to have data from the full 1,500-person study in the second half of 2018.

- read the statement