ABSTRACT
Chronic GVHD was recognized as a complication of allogeneic hematopoietic cell transplantation more than 30 years ago, but progress has been slowed by the limited insight into the pathogenesis of the disease and the mechanisms that lead to development of immunological tolerance. Only 6 randomized phase III treatment studies have been reported. Results of retrospective studies and prospective phase II clinical trials suggested overall benefit from treatment with mycophenolate mofetil or thalidomide, but these results were not substantiated by phase III studies of initial systemic treatment for chronic GVHD. A comprehensive review of published reports showed numerous deficiencies in studies of secondary treatment for chronic GVHD. Fewer than 10% of reports documented an effort to minimize patient selection bias, used a consistent treatment regimen, or tested a formal statistical hypothesis that was based on a contemporaneous or historical benchmark. In order to enable valid comparison of the results from different studies, eligibility criteria, definitions of individual organ and overall response, and time of assessment should be standardized. Improved treatments are more likely to emerge if reviewers and journal editors hold authors to higher standards in evaluating manuscripts for publication.