Frequency of major molecular responses to imatinib or interferon alfa plus cytarabine in newly diagnosed chronic myeloid leukemia.
BACKGROUND
In a randomized trial, 1106 patients with chronic myeloid leukemia (CML) in chronic phase were assigned to imatinib or interferon alfa plus cytarabine as initial therapy. We measured levels of BCR-ABL transcripts in the blood of all patients in this trial who had a complete cytogenetic remission.


METHODS
Levels of BCR-ABL transcripts were measured by a quantitative real-time polymerase-chain-reaction assay. Results were expressed relative to the median level of BCR-ABL transcripts in the blood of 30 patients with untreated CML in chronic phase.


RESULTS
In patients who had a complete cytogenetic remission, levels of BCR-ABL transcripts after 12 months of treatment had fallen by at least 3 log in 57 percent of those in the imatinib group and 24 percent of those in the group given interferon plus cytarabine (P=0.003). On the basis of the rates of complete cytogenetic remission of 68 percent in the imatinib group and 7 percent in the group given interferon plus cytarabine at 12 months, an estimated 39 percent of all patients treated with imatinib but only 2 percent of all those given interferon plus cytarabine had a reduction in BCR-ABL transcript levels of at least 3 log (P<0.001). For patients who had a complete cytogenetic remission and a reduction in transcript levels of at least 3 log at 12 months, the probability of remaining progression-free was 100 percent at 24 months, as compared with 95 percent for such patients with a reduction of less than 3 log and 85 percent for patients who were not in complete cytogenetic remission at 12 months (P<0.001).


CONCLUSIONS
The proportion of patients with CML who had a reduction in BCR-ABL transcript levels of at least 3 log by 12 months of therapy was far greater with imatinib treatment than with treatment with interferon plus cytarabine. Patients in the imatinib group with this degree of molecular response had a negligible risk of disease progression during the subsequent 12 months.
Hughes
Tim P
TP
Institute of Medical and Veterinary Science, Adelaide, SA, Australia. timothy.hughes@imvs.sa.gov.au
Kaeda
Jaspal
J
Branford
Susan
S
Rudzki
Zbigniew
Z
Hochhaus
Andreas
A
Hensley
Martee L
ML
Gathmann
Insa
I
Bolton
Ann E
AE
van Hoomissen
Iris C
IC
Goldman
John M
JM
Radich
Jerald P
JP
D000206:Actuarial Analysis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001549:Benzamides; D014408:Biomarkers, Tumor / Q000097:blood; D003561:Cytarabine / Q000627:therapeutic use*; D018572:Disease-Free Survival; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000097:blood*; D006801:Humans; D000068877:Imatinib Mesylate; D016898:Interferon-alpha / Q000627:therapeutic use*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D011743:Pyrimidines / Q000627:therapeutic use*; D012074:Remission Induction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects
D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D016898:Interferon-alpha; D010879:Piperazines; D011743:Pyrimidines; D003561:Cytarabine; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl