Observational Study Alternating R-CHOP21 and R-Cytarabine (3+3 Cycles) for Patients with Newly Diagnosed Mantle Cell Lymphoma Not Eligible for High-Dose Therapy: A Czech Lymphoma Study Group Trial Preliminary Results

Background: Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma characterized by frequent relapses and adverse prognosis. Implementation of high-dose cytarabine (HDAC) and incorporation of anti-CD20 antibody rituximab (R) into induction and maintenance, and consolidation with high-dose therapy and autologous stem cell transplantation (HDT-ASCT) significantly improved pt´s outcome. Therapy of the elderly or comorbid (not eligible for HDT-ASCT) is largely based on R-CHOP or R-bendamustin induction with or without R maintenance. Minimal residual disease (MRD) assessment by quantitative PCR (qPCR) from peripheral blood or bone marrow (BM) has emerged as a powerful molecular marker of outcome. Based on the results of the younger pts some centers adopted the use of HDAC in elderly as well, but no data has been presented yet.

Aim: We initiated the observational study as a non-intervention, multi-center trial with the primary objectives to prospectively evaluate efficacy of alternating R-CHOP21 and R-HDAC (1 or 2 g / m2, 2 doses a 24 hours) in newly diagnosed MCL pts not eligible for HDT-ASCT.

Methods: Primary endpoints were overall response rate (ORR) by PET-CT, and MRD assessment by qPCR after completion of induction. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity. The choice between 1 and 2 g / m2 cytarabine was left at investigator´s discretion, as well as the rituximab maintenance. Patients with known cardiac co-morbidity could be treated with R-COEP (etoposid 50 mg / m2, D1-D3) instead of R-CHOP. Exclusion criteria included eligibility to HDT-ASCT, ECOG≥ 4, and CNS involvement.

Results: Altogether 61 pts (38 men and 23 women, ratio 1.7:1) were enrolled into the study between 16-JUN-2011 and 18-MAR-2014. Median age was 70 years both for men and women. 91.5%, and 80% pts presented with stage 3/4 disease, and infiltration of BM, resp. According to the MIPI, 55.7%, 39.4%, and 4.9% pts had high, intermediate and low risk disease, resp. B-symptoms were recorded in 33.3% of pts. 76.8% and 24.2% pts were diagnosed from the lymph node, and trephine biopsy, resp. 62.8%, 27.9%, and 9.3% pts presented with classical, pleomorphic and blastoid variant MCL, resp. Ki67/MIB1 ≥ 30% was observed in 38% of pts. Bulky disease >5cm, and >10cm, was noticed in 31% and 13% pts. Spleen involvement was observed in 53% pts. Extra-nodal involvement other than BM was histologically confirmed in 11.5% pts. R-CHOP was used in 88% pts (12% pts received R-COEP), 86% pts received 2g / m2 cytarabine (14% pts 1g / m2). 86.3% pts with response were treated with R maintenace. Only one patient was excluded from the study due to unacceptable toxicity. 57.7% pts developed grade 3/4 hematologic toxicity (neutropenia, anemia or thrombocytopenia). Grade 3/4 non-hematologic toxicity occurred in 27.3% pts. All pts had PET-CT restaging after completion of induction. Overall response rate (CR+PR) reached 91.7%. CR and PR rate by PET was 76.7%, and 15%, resp. SD, and progression on therapy was noticed in 3.3%, and 5.0%, resp. Samples for MRD assessment were collected from 41 out of 54 pts, who completed induction and achieved response (CR or PR). At the time of abstract submission 21, 7, and 7 (out of 36 so far evaluated pts) were MRD negative, MRD positive-not quantifiable, and MRD positive-quantifiable, resp. With the median follow-up 19.1 month, there were 7 progressions and 6 deaths. 2-year PFS and OS probability were 83.9% and 88.1%.

Conclusion: Alternation of R-CHOP and R-HDAC in newly diagnosed elderly or co-morbid MCL pts represents a promising, very effective and well-tolerated treatment approach that induces high ORR, and MRD negativity.

Grant Support: IGA-MZ NT/13072-4, PRVOUK-27/LF1/1