Abstract

In Ph+ ALL, complete remission (CR) rates with intensive chemotherapy such hyper-CVAD is 90%, but most patients (pts) relapse within a median time of 16 months [

Kantarjian et al,
JCO
18
:
547
,
2000
;
Kantarjian et al,
Cancer
101
:
2788
,
2004
]. Single agent therapy with the tyrosine kinase inhibitor imatinib mesylate in relapsed or refractory Ph+ ALL or chronic myelogenous leukemia in lymphoid blast phase yielded CR rates of 20% with rapid disease recurrence. A phase II clinical trial of concurrent hyper-CVAD and imatinib was designed to improve these results, with the initial regimen of imatinib 400 mg orally daily days 1–14 of each course (fractionated cyclophosphamide, vincristine [VCR], doxorubicin and dexamethasone alternating with high dose methotrexate and cytarabine) followed by imatinib, VCR and prednisone maintenance with intensifications months 6 and 13. Allogeneic stem cell transplant (SCT) was performed in CR if feasible. Preliminary results of first 20 pts treated were encouraging [
Thomas et al,
Blood
103
:
4396
,
2004
]. Recent modifications included increasing dosing of imatinib to 600 mg daily days 1–14 of course 1, then daily if tolerated with courses 2–8. Maintenance was extended to 24 months with imatinib indefinitely. To date, 43 pts with Ph+ ALL have been treated from April 2004 to July 2005. Thirty-six pts had active disease, either untreated (n=31) or refractory (n=1) to one induction course without imatinib; 7 pts were in CR after one induction course without imatinib. Of 35 evaluable pts, 33 (94%) achieved CR (1 induction death, 1 failed to meet platelet criteria for CR). Median days to response was 21 days. 13 pts underwent allogeneic SCT within a median of 3 months from start of therapy (range, 1–12). After a median follow-up of 3 yrs (range 1–48 months), 1 primary refractory pt relapsed at 12 months, 1 de novo pt had isolated CNS relapse, 2 pts relapsed after allogeneic SCT (no post SCT imatinib) and 2 pts changed therapy for persistent Ph+ metaphases (1 relapsing). Deaths in CR included 5 older pts without allogeneic SCT (1 osteomyelitis, 1 mucormycosis, 1 C. difficile colitis, 1 sudden death, 1 GNR sepsis) and 4 pts after allogeneic SCT (3 graft-versus-host disease, 1 GNR sepsis). Outcome with the hyper-CVAD and imatinib regimen continues to demonstrate favorable disease-free survival rates compared with hyper-CVAD alone, particularly for the de novo group. Use of higher dose imatinib concurrently appears to be feasible. Molecular response rates appear to be improved with the higher dose imatinib; additional accrual will be required to assess impact of modifications, including role of allogeneic SCT.

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