The Phase 3 IMAGINE trial, designed to assess the efficacy of clazakizumab in treating chronic active antibody-mediated rejection (caAMR) in kidney transplant recipients, was halted prematurely after an interim analysis indicated it would not meet its primary endpoint. The study, the largest placebo-controlled trial in this patient population, aimed to evaluate whether clazakizumab could stabilize kidney function and prevent allograft loss.
IMAGINE Trial Design and Interim Analysis
The international, double-blind IMAGINE trial randomized approximately 350 kidney transplant recipients with caAMR in a 1:1 ratio to receive either clazakizumab or placebo. The primary efficacy outcome was defined as the time to a composite endpoint of all-cause allograft loss or irreversible loss of allograft function. Notably, the trial's design incorporated a 1-year estimated glomerular filtration rate (eGFR) slope, a measure of kidney function changes, which had been accepted by the FDA as a reasonably likely surrogate endpoint.
However, an interim analysis conducted after approximately 100 participants completed one year of the study revealed that clazakizumab was unlikely to demonstrate a significant benefit in achieving the primary efficacy outcome. Consequently, the data and safety monitoring board recommended the termination of the trial.
Final Analysis and Results
The final analysis, conducted following the early termination, focused on the change in eGFR from baseline at week 52. The results indicated no statistically significant difference in the Least Squares mean change in eGFR between the clazakizumab and placebo groups. Furthermore, the study did not identify any new safety concerns associated with clazakizumab treatment.
Implications and Future Directions
According to Arjang Djamali, MD, of Maine Medical Center, treating patients with caAMR remains a significant challenge. While the results of the IMAGINE trial are disappointing, Djamali emphasized the ongoing commitment to advancing research and addressing the unmet needs of kidney transplant patients. The researchers expressed gratitude to the patients, research sites, and CSL, the study sponsor, for their contributions to the trial.
Clazakizumab is a monoclonal antibody that targets interleukin-6 (IL-6), an inflammatory cytokine. Chronic active antibody-mediated rejection (caAMR) is a major cause of allograft loss after kidney transplantation, and currently, there are no approved therapies specifically targeting this condition.
