Subject terms
aggressive lymphoma, Richter transformation, Richter’s transformation
CHRONIC LYMPHOCYTIC LEUKEMIA
In patients with chronic lymphocytic leukemia, Richter transformation (RT) reflects the development of an aggressive lymphoma that is associated with poor response to chemotherapy and short survival. We initiated an international, investigator-initiated, prospective, open-label phase 2 study in which patients with RT received a combination of the PD-1 inhibitor tislelizumab plus the BTK inhibitor zanubrutinib for 12 cycles. Patients responding to treatment underwent maintenance treatment with both agents. The primary end point was overall response rate after six cycles. Of 59 enrolled patients, 48 patients received at least two cycles of treatment and comprised the analysis population according to the study protocol. The median observation time was 13.9 months, the median age was 67 (range 45–82) years. Ten patients (20.8%) had received previous RT-directed therapy. In total, 28 out of 48 patients responded to induction therapy with an overall response rate of 58.3% (95% confidence interval (CI) 43.2–72.4), including 9 (18.8%) complete reponse and 19 (39.6%) partial response, meeting the study’s primary end point by rejecting the predefined null hypothesis of 40% (In a large single-arm phase 2 trial, the anti-PD-1 inhibitor tislelizumab combined with the next-generation BTK inhibitor zanubrutinib had an overall response rate of 58.3% and was well tolerated in patients with Richter’s transformation.