Lymphocyte recovery after bendamustine therapy in patients with mantle cell lymphoma. Results of a retrospective analysis and prognostic impact in the CAR-T era.

Bendamustine in combination with rituximab (BR) or with rituximab and cytarabine (R-BAC) is the standard first-line immunochemotherapy in mantle cell lymphoma (MCL) for elderly patients and patients ineligible for intensive regimens or autologous transplantation. As bendamustine causes prolonged lymphopenia and the literature lacks evidence of its persistence in patients with MCL, this retrospective analysis aims to estimate the lymphocyte recovery time, also in view of potential immunotherapy with CAR-T cells. Data were collected from 44 consecutive MCL patients who received bendamustine (BR or R-BAC) as first-line therapy at the Hematology Unit of Sapienza University Hospital between May 2011 and April 2022. Twenty patients (45%) were treated with R-BAC and 24 (55%) with BR. At baseline, the median lymphocyte count was 1795/µl (range: 370-11730/µL). One month after the end of therapy, it was 450/µl (range: 50-3300/µl) and 3 months after 768/µl (range: 260-1650/µl). After 6 and 9 months, we observed a gradual increase in median lymphocyte count of 900/µl (range: 370-2560/µl and 130-2770/µl, respectively). After 12 months median lymphocyte count was 1256/µl (range: 240-4140/µl). Median lymphocyte count at 1, 3, 6, and 9 months post-treatment was significantly lower than baseline but showed recovery by the 12 months. This finding is crucial for MCL patients considering CAR-T cell therapy, suggesting a minimum 9-month interval between bendamustine administration and leukapheresis.