Chemoimmunotherapy with a Modified Hyper-CVAD and Rituximab Regimen Improves Outcome for Patients with De Novo Philadelphia Negative Precursor B-Cell Acute Lymphoblastic Leukemia (ALL).

Abstract 836

The hyper-CVAD regimen is an effective frontline program for de novo adult ALL and LL [Kantarjian, JCO 18:547, 2000; Kantarjian, Cancer 101:2788, 2004, Thomas, Blood 104:1624, 2004]. Intensive chemotherapy with hyper-CVAD (fractionated cyclophosphamide, vincristine [VCR], doxorubicin, dexamethasone) alternates with high dose methotrexate (MTX) and cytarabine every 21 days for 8 courses, followed by maintenance therapy with POMP (6-mercaptopurine, MTX, VCR, prednisone). Historical CR rate was 92% with 3-year disease-free survival (DFS) rate of 38%. The regimen was modified in 1999. Induction chemotherapy was given in a protective environment owing to higher mortality in patients (pts) aged 60 years or older (17% vs 3%). Course 2 of liposomal daunorubicin and cytarabine was incorporated owing to reports suggesting benefit of early anthracycline intensification. Rituximab 375 mg/m2 (days 1 & 11 of hyper-CVAD, days 1 & 8 of methotrexate-cytarabine) was given if CD20 expression was 20% or greater due to its association with disease recurrence [Thomas, Blood 113:6330, 2009]. The maintenance phase was extended to 30 months with additional intensifications owing to late relapses after completion of POMP therapy. Newly diagnosed or primary refractory (1 course only) pts with ALL (n=204) or LL (n=27) were treated on the two sequential studies. Burkitt-type leukemia/lymphoma (BLL) and Philadelphia positive ALL were treated on alternative protocols. From May 2000 to December 2001, 69 pts were treated with modified hyper-CVAD with anthracycline intensification (9 induction-consolidation courses). Course 2 was then eliminated from the regimen (8 courses), with an additional 162 pts treated to date (pts age 30 years or less are now treated with augmented BFM). Median age was 43 yrs (range, 15–83). CD20 expression was noted in 49%. Overall CR rate of the evaluable group (n=225) was 93%; 7 pts achieved PR (LL with residual disease), five failed to respond, and 4 died during the induction phase. Three-yr CRD and OS rates were 70% and 62%, respectively after a median follow-up of 50 months (range, 2–106+). In the younger CD20 positive precursor B-cell ALL subset (n=99), rituximab improved outcome compared to historical experience with hyper-CVAD alone (n=127), with 3-yr CRD rates (75% vs 45%, p<.001) and OS rates (65% vs 38%, p<.001) approaching those of their CD20 negative counterparts. In contrast to the Burkitt experience, rituximab was not beneficial for the elderly subgroup (OS rates 28% vs 34%, p NS). Anthracycline intensification did not improve outcome. The addition of rituximab to the hyper-CVAD regimen appears to benefit the younger pts (age less than 60 yrs) with CD20 positive precursor B-cell ALL. Incorporation of rituximab and other monoclonal antibodies (e.g., ofatumumab, epratuzumab) into frontline chemotherapy regimens for ALL should be investigated systematically.