First Results of the GRAAPH-2005 Study in younger Adult Patients with De Novo Philadelphia Positive Acute Lymphoblastic Leukemia

The GRAAPH-2005 International study for adults with newly diagnosed chromosome Philadelphia positive (Ph+) acute lymphoblastic leukemia (ALL) was designed to compare an imatinib-based induction regimen with an imatinib-HyperCVAD induction regimen and to evaluate the role of imatinib prior to stem cell transplantation (SCT).

The protocol enrolled patients > 18 years and < 60 years. Among 118 enrolled patients from May 2006 onwards, 83 had a follow-up long enough to allow at least induction and consolidation evaluation. Median age was 42 years; 60% were male. A 7-day pre-phase steroid regimen (prednisone 60 mg/m²/day) allowed identification of the BCR/ABL transcript. In arm A (imatinib-based), imatinib 800 mg was given days 1-28, only combined with vincristine (2 mg at days 1, 8, 15, 22) and dexamethasone (40 mg at days 1-2, 8-9, 15-16, and 22-23). In arm B (imatinib-HyperCVAD), imatinib 800 mg was given days 1-14 of each course, combined with adriamycin (50 mg/m² at day 4), cyclophosphamide (300 mg/m²/12h at day 1, 2, 3), vincristine (2 mg at days 4 and 11), and dexamethasone (40 mg at days 1-4 and 11-14) in the induction course, and combined with high-dose methotrexate (1 g/m² at day 1) and high-dose cytarabine (3 g/m²/12h at days 2 and 3) in the salvage/consolidation course. Salvage/consolidation course was similar for patients initially following arm A. Four intrathecal infusions (methotrexate + cytarabine + methylprednisolone) were included within induction/consolidation courses. Complete hematological remission (CR) rate at the end of the two courses of induction/consolidation was 100% with arm A (42 patients of whom 2 after salvage course) and 95% with arm B (39/41 patients; all after induction course): overall 97.5% vs 70% in the pre imatinib era (LALA-94 trial). One patient died during the first course and 2 during the second course (of which 1 in CR after the induction course). Overall, median number of days to response was 37 (range, 28-136 days). Minimal residual disease (MRD) was centrally evaluated by quantitative RT-PCR at the end of induction (MRD-1) and at the end of salvage/consolidation chemotherapy (MRD-2). Molecular disease was undetectable in 11% at the time of MRD-1 and in 18% at the time of MRD-2, and at a level < 0.1% in 40% at the time of MRD-1 and in 60% at that of MRD-2. Although this did not translate into significant difference in terms of survival, monitoring of MRD (< 0.1%) documented that arm B was capable of inducing a deeper marked clearance of leukemic cells than arm A at the end of salvage/consolidation chemotherapy: 35% in arm A and 45% in armB (p = 0.3) for MRD-1, and 48% in arm A and 72% in arm B (p = 0.05) for MRD-2. After the two phases of induction/consolidation, patients received intensification by allogeneic SCT using related or unrelated donor stem cells or autologous SCT when a donor was not available and MRD < 0.1%. In absence of potential SCT, they underwent repeated cycles of imatinib-HyperCVAD regimen. Of the 61 patients with enough follow-up after induction/consolidation courses, 52 (85%) actually received SCT: 41 allogeneic SCT (of which 25 from related- and 16 from unrelated-donor) and 11 autologous SCT. Overall survival (OS) was 62% at 2-year (68% and 54% in arm A and arm B, respectively; p = 0.3), which differ significantly from the 29% observed in the pre imatinib era (LALA-94 trial). Disease-free survival (DFS) was 43% at 2-year (54% and 32% in arm A and arm B, respectively; p = 0.7). After a median follow-up of 12.6 months (95% CI, 10.6-15 months), 18 relapses (22%) were observed. Eighteen patients have died after induction/consolidation phase: 8 patients with progressive disease and 10 patients in CR (1 from septic shock waiting for allogeneic SCT, and 9 from toxicity during allogeneic SCT).

The preliminary data of this study suggest that an imatinib-based regimen induces a high rate of hematological CR, similar to a more intensive (HyperCVAD) regimen. However the rate of molecular response has a tendency to be lower with imatinib-based regimen. The combination of imatinib with chemotherapy allows a majority of patient to have consolidation with SCT.