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 prephase 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.