Frequency and type of mutations at start of treatment
| Time of sample collection . | No. of patients analyzed . | Patients with WT BCR-ABL, n (%) . | n (%) mutations . | |
|---|---|---|---|---|
| Overall . | P-loop . | |||
| All samples collected prior to or during induction therapy | 42 | 25/42 (60) | 17/42 (40) | 13/42 (31) |
| Prior to induction therapy | 22 | 13/22 (59) | 9/22 (41) | 7/22 (32) |
| During chemotherapy induction, prior to imatinib | 10 | 7/10 (70) | 3/10 (30) | 3/10 (30) |
| All patients prior to imatinib | 32 | 20 (63) | 12 (37) | 10 (33) |
| During imatinib induction | 10 | 5 (50) | 5 (50) | 3 (30) |
| Time of sample collection . | No. of patients analyzed . | Patients with WT BCR-ABL, n (%) . | n (%) mutations . | |
|---|---|---|---|---|
| Overall . | P-loop . | |||
| All samples collected prior to or during induction therapy | 42 | 25/42 (60) | 17/42 (40) | 13/42 (31) |
| Prior to induction therapy | 22 | 13/22 (59) | 9/22 (41) | 7/22 (32) |
| During chemotherapy induction, prior to imatinib | 10 | 7/10 (70) | 3/10 (30) | 3/10 (30) |
| All patients prior to imatinib | 32 | 20 (63) | 12 (37) | 10 (33) |
| During imatinib induction | 10 | 5 (50) | 5 (50) | 3 (30) |
To determine the prevalence of BCR-ABL KD mutations at the beginning of treatment, we examined 42 patients by D-HPLC. Thirty-two of these patients were imatinib-naive, 22 of whom had received either no or only prephase therapy. Samples from the other 10 imatinib-naive patients were collected within the first 2 to 4 weeks of induction chemotherapy, before commencement of imatinib. In an additional 10 cases, the first available sample was obtained during the first 4 weeks of single-agent imatinib induction. WT (wild-type) denotes unmutated BCR-ABL. The frequency of the mutant allele prior to induction therapy was always low, ranging from 0.1% to 2% (median, 0.5%).