Children's Oncology Group AALL0434: A Phase III Randomized Clinical Trial Testing Nelarabine in Newly Diagnosed T-Cell Acute Lymphoblastic Leukemia.

PURPOSE: Nelarabine is effective in inducing remission in patients with relapsed and refractory T-cell acute lymphoblastic leukemia (T-ALL) but has not been fully evaluated in those with newly diagnosed disease. PATIENTS AND METHODS: From 2007 to 2014, Children's Oncology Group trial AALL0434 (ClinicalTrials.gov identifier: NCT00408005) enrolled 1,562 evaluable patients with T-ALL age 1-31 years who received the augmented Berlin-Frankfurt-Muenster (ABFM) regimen with a 2 × 2 pseudo-factorial randomization to receive escalating-dose methotrexate (MTX) without leucovorin rescue plus pegaspargase (C-MTX) or high-dose MTX (HDMTX) with leucovorin rescue. Intermediate- and high-risk patients were also randomly assigned after induction to receive or not receive six 5-day courses of nelarabine that was incorporated into ABFM. Patients who experienced induction failure were nonrandomly assigned to HDMTX plus nelarabine. Patients with overt CNS disease (CNS3; ≥ 5 WBCs/µL with blasts) received HDMTX and were randomly assigned to receive or not receive nelarabine. All patients, except those with low-risk disease, received cranial irradiation. RESULTS: The 5-year event-free and overall survival rates were 83.7% ± 1.1% and 89.5% ± 0.9%, respectively. The 5-year disease-free survival (DFS) rates for patients with T-ALL randomly assigned to nelarabine (n = 323) and no nelarabine (n = 336) were 88.2% ± 2.4% and 82.1% ± 2.7%, respectively (P = .029). Differences between DFS in a four-arm comparison were significant (P = .01), with no interactions between the MTX and nelarabine randomizations (P = .41). Patients treated with the best-performing arm, C-MTX plus nelarabine, had a 5-year DFS of 91% (n = 147). Patients who received nelarabine had significantly fewer isolated and combined CNS relapses compared with patients who did not receive nelarabine (1.3% ± 0.63% v 6.9% ± 1.4%, respectively; P = .0001). Toxicities, including neurotoxicity, were acceptable and similar between all four arms. CONCLUSION: The addition of nelarabine to ABFM therapy improved DFS for children and young adults with newly diagnosed T-ALL without increased toxicity.

Improved Survival for Children and Young Adults With T-Lineage Acute Lymphoblastic Leukemia: Results From the Children's Oncology Group AALL0434 Methotrexate Randomization.

PURPOSE: Early intensification with methotrexate (MTX) is a key component of acute lymphoblastic leukemia (ALL) therapy. Two different approaches to MTX intensification exist but had not been compared in T-cell ALL (T-ALL): the Children's Oncology Group (COG) escalating dose intravenous MTX without leucovorin rescue plus pegaspargase escalating dose, Capizzi-style, intravenous MTX (C-MTX) regimen and the Berlin-Frankfurt-Muenster (BFM) high-dose intravenous MTX (HDMTX) plus leucovorin rescue regimen. PATIENTS AND METHODS: COG AALL0434 included a 2 × 2 randomization that compared the COG-augmented BFM (ABFM) regimen with either C-MTX or HDMTX during the 8-week interim maintenance phase. All patients with T-ALL, except for those with low-risk features, received prophylactic (12 Gy) or therapeutic (18 Gy for CNS3) cranial irradiation during either the consolidation (C-MTX; second month of therapy) or delayed intensification (HDMTX; seventh month of therapy) phase. RESULTS: AALL0434 accrued 1,895 patients from 2007 to 2014. The 5-year event-free survival and overall survival rates for all eligible, evaluable patients with T-ALL were 83.8% (95% CI, 81.2% to 86.4%) and 89.5% (95% CI, 87.4% to 91.7%), respectively. The 1,031 patients with T-ALL but without CNS3 disease or testicular leukemia were randomly assigned to receive ABFM with C-MTX (n = 519) or HDMTX (n = 512). The estimated 5-year disease-free survival ( P = .005) and overall survival ( P = .04) rates were 91.5% (95% CI, 88.1% to 94.8%) and 93.7% (95% CI, 90.8% to 96.6%) for C-MTX and 85.3% (95% CI, 81.0%-89.5%) and 89.4% (95% CI, 85.7%-93.2%) for HDMTX. Patients assigned to C-MTX had 32 relapses, six with CNS involvement, whereas those assigned to HDMTX had 59 relapses, 23 with CNS involvement. CONCLUSION: AALL0434 established that ABFM with C-MTX was superior to ABFM plus HDMTX for T-ALL in approximately 90% of patients who received CRT, with later timing for those receiving HDMTX.