Unfolding a CLL mystery.

摘要

In this issue, Del Giudice and colleagues report on 9 patients with CLL who had a spontaneous regression of their tumors, providing new insights into this intriguing phenomenon. It has been known since the 1990s, mainly through anecdotal cases, that cancer can spontaneously regress (ie, complete or partial regression, usually transient, of the disease with no therapeutic intervention). However, this is a rare event with an estimated incidence of 1% in chronic lymphocytic leukemia (CLL). Although described in virtually all types of cancer, this phenomenon is most frequently seen in tumors considered to be especially sensitive to immunoregulation. The mechanisms involved in spontaneous regression of CLL are poorly characterized. Understanding the mechanisms leading to spontaneous regression would provide important biologic clues, and identify potential new treatment strategies. Which patients are most likely to undergo spontaneous tumor regression? What are the mechanisms inducing regression? What triggers it? Why is this usually a transient phenomenon?