A half-log increase in BCR-ABL RNA predicts a higher risk of relapse in patients with chronic myeloid leukemia with an imatinib-induced complete cytogenetic response.
OBJECTIVE
Imatinib induces a complete cytogenetic response (CCR) in most chronic myeloid leukemia patients in chronic phase. Although CCR is usually durable, a minority of patients relapse. Biomarkers capable of predicting those CCR patients with a higher risk of relapse would improve therapeutic management.


METHODS
To assess whether changes in BCR-ABL RNA levels are a prognostic biomarker predictive of relapse, we regularly monitored transcript levels [every 3 months (median)] in 90 patients with CCR during 49 months (median) of imatinib therapy.


RESULTS
Throughout follow-up, the 20 patients with eventual relapse had higher transcript levels than the durable responders. Major molecular response (MMR; >3-log reduction of BCR-ABL RNA) was attained by 76 patients (12 with subsequent relapse) and was a significant predictor of prolonged relapse-free survival (P = 0.0008). A minimal 0.5-log increase in transcripts (before relapse; experienced by 42 patients, 16 with subsequent relapse) conveyed a significantly shorter relapse-free survival (P = 0.0017). Loss of MMR (transcript increase to <2.5-log reduction, before relapse; experienced by 33 patients, 11 with subsequent relapse) was also predictive of shortened relapse-free survival (P = 0.0003). A complete molecular response (undetectable transcripts by nested PCR) was attained by 28 MMR patients (one with subsequent relapse) and conveyed a significantly prolonged relapse-free survival (P = 0.0052).


CONCLUSIONS
In chronic myeloid leukemia patients with an imatinib-induced CCR, a minimal half-log increase in BCR-ABL RNA (including loss of MMR) is a significant risk factor for future relapse. The achievement of a complete molecular response imparts longer progression-free survival than the achievement of an MMR.
Press
Richard D
RD
Department of Pathology, Center for Hematologic Malignancies, Cancer Institute, and Howard Hughes Medical Institute, Oregon Health & Science University, Portland, Oregon 97201, USA. pressr@ohsu.edu
Galderisi
Chad
C
Yang
Rui
R
Rempfer
Carole
C
Willis
Stephanie G
SG
Mauro
Michael J
MJ
Druker
Brian J
BJ
Deininger
Michael W N
MW
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D014408:Biomarkers, Tumor; D003582:Cytogenetics; D004252:DNA Mutational Analysis; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D000068877:Imatinib Mesylate; D007700:Kinetics; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D011743:Pyrimidines / Q000627:therapeutic use*; D012334:RNA, Neoplasm / Q000378:metabolism; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D010879:Piperazines; D011743:Pyrimidines; D012334:RNA, Neoplasm; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl