Treosulfan-Based Tandem High-Dose Chemo-Immuno- Therapy with Autologous Stem Cell Transplantation for Relapsed and Refractory Aggressive B-Cell Lymphomas.

Feasibility and high efficacy of repetitive dose-intensive chemo-immuno-therapy in relapsed and refractory aggressive B-cell lymphoma (adjusted IPI at relapse 2 and 3) was proven by double-induction followed by tandem high-dose chemo-immuno-therapy with stem cell transplantation including a treosulfan-based conditioning regimen. For cytoreduction and stem cell mobilisation, 2 cycles of a cisplatin-based chemotherapy plus rituximab (R), R-VIPE or R-DHAP, were applied followed by two identical cycles of high-dose chemotherapy (HD-CT) consisting of treosulfan 14 g/m² iv day −4 to day -2, carboplatin 300 mg/m² iv day −4 to day −2 and etoposide 500 mg/m² iv day −2 to day −4. Each HD-CT was combined with rituximab 375 mg/m². Thirty patients (pts), mean age 53 years (range 35–68), stage III: n=9, stage IV: n=21, have been enrolled. 80% of the pts suffered from early relapse within 6 months (n=6) or refractory disease and no available matched related or unrelated donor (n=18), 6 pts had a late relapse (≥ 6 months). All patients received previously CHOP-based CTs. Histology revealed diffuse-large cell lymphoma (n=19), follicular lymphoma Grade 3 (n=6), immunoblastic lymphoma (n=3), and mantle cell lymphoma (n=2). In 7 pts both, low- and high-grade lymphomas were observed. Only one stem cell mobilization was necessary to collect sufficient CD34+ cells for two transplantations. Median hematologic recovery (> 1.0 leukocytes/nl and platelets >20/nl) after 1^st and 2^nd HD-CT was achieved by day 10 (8–11). No therapy-related death occurred. CTC °III and °IV non-hematologic toxicities were as follows: 11 of 29 pts after 1^st HD-CT had °III toxicities (infection, vomiting, enteritis, stomatitis, diarrhea), after 2^nd HD-CT 10 of 27 pts, respectively. Complete remission (CR 3 months post transplantation) was achieved in 22 of 30 pts (73%). CR was documented after double-induction (n=2), 1^st HD-CT (n=9), and 2^nd HD-CT (n=11), PR in 6 pts, and 2 pts had progressive disease during induction CT and HD-CT, respectively. At a median observation time of 19 months (range 3.6 to 4.6 months) 26 pts (87%) are alive. Sequential R-HD-CT results (in poor risk pts) in a median PFS of 14.0 months (CI 8.7 to 19.3 months), median overall survival (OS, intent-to-treat analysis) has not been reached (at 4 years 72%). In conclusion, treosulfan-based tandem R-HD-CT is feasible with a manageable toxicity profile. CR and continuous CR rates argue for a dose-response relationship even in high-risk patients with aggressive B-cell lymphomas. Some poor risk pts seem to be cured with the treosulfan-based HD-chemo-immuno-therapy. In cases of progression rescue therapies may be successfully administered as shown by the favorable OS rate. This study has now been extended as a multicenter trial.