Results of the APML3 trial incorporating all-trans-retinoic acid and idarubicin in both induction and consolidation as initial therapy for patients with acute promyelocytic leukemia

Riferimento: 
Haematologica. 2012 Feb;97(2):227-34.
Autori: 
Iland H, Bradstock K, Seymour J, Hertzberg M, Grigg A, Taylor K, Catalano J, Cannell P, Horvath N, Deveridge S, Browett P, Brighton T, Chong L, Springall F, Ayling J, Catalano A, Supple S, Collins M, Di Iulio J, Reynolds J; Australasian Leukaemia ...
Fonte: 
Haematologica. 2012 Feb;97(2):227-34.
Anno: 
2012
Azione: 
La combinazione di acido all-trans retinoico (ATRA) e solo due cicli di idarubicina seguita da mantenimento produce remissioni durature nella maggior parte dei pazienti con leucemia promielocitica acuta (APML).
Target: 
ATRA-Idarubicina/leucemia promielocitica acuta.

BACKGROUND:
Initial therapy for patients with acute promyelocytic leukemia most often involves the combination of all-trans-retinoic acid with anthracycline-based chemotherapy. The role of non-anthracycline drugs in induction and consolidation is less well-established and varies widely between different cooperative group protocols.
DESIGN AND METHODS:
In an attempt to minimize relapse and maximize survival for patients with newly diagnosed acute promyelocytic leukemia, the Australasian Leukaemia and Lymphoma Group utilized all-trans-retinoic acid and idarubicin as anti-leukemic therapy for both induction and consolidation. The protocol (known as APML3) was subsequently amended to incorporate maintenance with all-trans-retinoic acid, methotrexate and 6-mercaptopurine.
RESULTS:
Eight (8%) of 101 patients died within 30 days, and 91 (90%) achieved complete remission. With a median estimated potential follow-up of 4.6 years, 4-year overall survival was 84%, and 71% of the patients remained in remission at 4 years. The cumulative incidence of all relapses was 28.1%, with 15 of the 25 relapses initially identified as an isolated molecular relapse. Both FLT3 mutations (internal tandem duplications and codon 835/836 kinase domain mutations) and increased white cell count at diagnosis were associated with inferior overall survival, but in multivariate analyses only FLT3 mutations remained significant (hazard ratio 6.647, P=0.005). Maintenance therapy was significantly associated with improved remission duration (hazard ratio 0.281, P<0.001) and disease-free survival (hazard ratio 0.290, P<0.001).
CONCLUSIONS:
The combination of all-trans-retinoic acid and just two cycles of idarubicin followed by triple maintenance produced durable remissions in most patients, but patients with high-risk disease, especially those with FLT3 mutations, require additional agents or alternative treatment approaches. The significant reduction in relapse seen after the addition of maintenance to the protocol supports a role for maintenance in the context of relatively low chemotherapy exposure during consolidation.

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