The BCR-ABL1 rise was consistent with an exponential growth model; therefore, the doubling time for individual patients remained constant over time. (A) Twenty-nine patients had more than 2 consecutive BCR-ABL1 measurements during the time of the rise and did not have a change of therapy. Patients 1 to 15 discontinued imatinib in CMR or had a complete interruption during the measurement intervals, whereas patients 16 to 29 had a mutation and maintained CP. The exponential nature of the rise meant that the doubling time of the first rise was consistent with the rise that occurred in the second measurement interval. Only 1 patient had a doubling time that differed by greater than 2.5 times at the second rise (patient 7). (B-C) Representative plots of the BCR-ABL1 rise of 2 patients to demonstrate that the doubling time remained constant wherever the rise was measured: over the first rise, the second rise, or over the duration of the total rise. In contrast, the fold rise was highly variable for each of these measurements. A shorter measurement interval led to a smaller rise (B, second rise; and C, first rise), whereas a longer measurement interval led to a greater rise (B, first rise; and C, second rise). The total fold rise was similar for both patients, although the kinetics were markedly different.