A. Hochhaus et al., VARIABLE NUMBERS OF BCR-ABL TRANSCRIPTS PERSIST IN CML PATIENTS WHO ACHIEVE COMPLETE CYTOGENETIC REMISSION WITH INTERFERON-ALPHA, British Journal of Haematology, 91(1), 1995, pp. 126-131
A substantial minority of patients with chronic myeloid leukaemia (CML
) achieve a complete response to treatment with interferon-alpha (IFN-
alpha), defined as the disappearance of Philadelphia chromosome positi
ve metaphases or, for patients who are Philadelphia chromosome negativ
e but BCR-ABL positive, the disappearance of the leukaemic clone as as
sayed by Southern blot. We have measured the levels of BCR-ABL transcr
ipts in 20 such patients by quantitative PCR. Results were standardize
d for both quality and quantity of cDNA by quantification of ABL as an
internal control. All 20 patients had evidence of residual disease; t
he median number of transcripts was 750/mu g RNA (range 10-22 000) and
the median BCR-ABL/ABL ratio was 0.17% (range 0.0008-3.6%). Our findi
ngs show that CML has not been eradicated in any patient and that the
quantity of residual disease in complete responders may vary by as muc
h as four orders of magnitude.