Alternating Courses of 3x CHOP and 3x DHAP Plus Rituximab Followed by a High Dose ARA-C Containing Myeloablative Regimen and Autologous Stem Cell Transplantation (ASCT) Increases Overall Survival When Compared to 6 Courses of CHOP Plus Rituximab Followed by Myeloablative Radiochemotherapy and ASCT in Mantle Cell Lymphoma: Final Analysis of the MCL Younger Trial of the European Mantle Cell Lymphoma Network (MCL net)
Authors: Hermine Olivier , Hoster Eva , Walewski Jan , Ribrag Vincent , Brousse Nicole , Thieblemont Catherine , Bouabdallah Reda , Dohner Hartmut , Feugier Pierre , Forspointner Roswitha , Haioun Corinne , Kneba Michael , Hänel Mathias , Casasnovas Olivier , Mertelsmann Roland H. , Hallek Michael , Bosly Andre , Nowacki M , Klapper Wolfram , Gisselbrecht Christian , Coiffier Bertrand , Unterhalt Michael , Hiddemann Wolfgang , Dreyling Martin H. 
Published: October 2019

Abstract 151

Background

MCL outcome has improved during the last decades. In its first randomized trial, the MCL net demonstrated that myeloablative consolidation followed by ASCT resulted in a significant prolongation of PFS in advanced stage MCL (Dreyling et al Blood 2005). Recent phase II studies suggest that the addition of rituximab and/or high dose ARA-C may significantly improve outcome. A phase II trial using sequential R-CHOP/R-DHAP followed by ASCT showed an ORR of 95% with a CR rate of 61%, a median EFS of 83m and a 75% survival rate at 5 years (Delarue et al Blood 20012). Two years ago we presented preliminary results of the the MCL randomized trial comparing 6 courses of CHOP plus Rituximab followed by myeloablative radiochemotherapy (12 Gray TBI, 2×60mg/kg Cyclophosphamide) and ASCT (control arm A) versus alternating courses of 3x CHOP and 3x DHAP plus Rituximab followed by a high dose ARA-C containing myeloablative regimen (10 Gray TBI, 4×1,5 g/m2 Ara-C, 140mg/m2 melphalan) and ASCT (experimental arm B) and have shown that after a follow up (FU) median of 27m patients of Arm B experienced a significantly better time to treatment failure (TTF) (49m vs NR; p=0.0384, HR 0.68), but no overall survival difference. Here, we present final results after a longer FU.

Methods

Patient eligibility criteria included previously untreated MCL stage II-IV up to the age of 65 years. Histological diagnosis was confirmed by a central pathology review board. The primary end point TTF was monitored continuously by a sequential procedure based on a one sided triangular test. Stable diseases after induction, progression or death from any causes were considered as treatment failure. Sample size was calculated to detect a relative risk of 52% for arm B with a power of 95%. Randomization was stopped as soon as a significant difference was observed between the two arms.

Results

From July 2004 to May 2010, 497 patients were randomized in 4 countries (Germany, France, Poland, Belgium). The 455 patients evaluable for the primary analysis (19 no MCL, 13 not yet documented, 7 lost of follow up, 2 stage 1, and 1 R bendamustine chemotherapy) displayed the following characteristics (A vs B): median age 54 vs 56 year, male 79% vs 79%, stage IV 82% vs 81%, B symptoms 43% vs 31%, ECOG >2 4% vs 4%, elevated LDH 39% vs 35%, and MIPI low/int/high risk 60%/25%/15% vs 64%/23%/13%, respectively. After induction overall response (OR) was similar in both arms (90% vs 95%; p=0.19) but CR and CR/CRu rates were significantly higher in arm B (25% vs 36%; p=0.012 and 40% vs 54%; p=0.0003). The number of patients transplanted was similar in both arms (72% vs 73%). After transplantation OR and CR rates were comparable in both arms (98% vs 97% and 63% vs 61%). After a median FU of 51 months, TTF was longer in Arm B (46m vs 88m; p=0.0382, HR 0.68) mainly due to a lower number of relapses after CR/CRu/PR (n= 81 vs 40). The rate of ASCT-related death in remission was similar in both arms (4% vs 4%). Although CR rate after ASCT was similar in both arms, remission duration (RD) after ASCT was superior in Arm B (49m vs 84m; p=0.0001). At the time of final analysis, OS was superior in Arm B (NR vs 82m, p=0.045). Safety after induction was comparable in both arms except for an increased grade 3/4 hematological toxicity (Hb 9% vs 30%, WBC 50% vs 75%, platelets 10% vs 74%), renal toxicity (creatinine grade 1/2: 10% vs 44%, grade 3/4: none vs 1%), and grade 1/2 nausea and vomiting in arm B. Toxicities of both conditioning regimen were similar.

Conclusions

With a longer FU, we confirmed that high dose ARA-C in addition to R-CHOP increases significantly complete response rates, TTF and in addition overall survival without clinically relevant increase of toxicity. Therefore, induction regimen containing high dose ARA-C followed by ASCT should become the new standard of care of MCL patients <65 y.

Disclosures:

Ribrag: Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; astrazeneca: Membership on an entity's Board of Directors or advisory committees; takeda: Membership on an entity's Board of Directors or advisory committees; bayer: Research Funding; sanofi: Research Funding. Gisselbrecht:roche: Consultancy, Research Funding; baxter: Research Funding.