CML-393: Incidence of Deep Molecular Response and Its Association with Clinical and Molecular Variables in Patients with Chronic Myeloid Leukemia Treated with Imatinib in a Population with Limited Health Resources

Abstract

Context Since deep molecular response (DMR) confers a better progression-free survival in chronic myeloid leukemia (CML), it is now a primary goal and also is an absolutely requirement for therapy discontinuation. Objective Here, we investigate the incidence of DMR and its association with clinical and molecular variables. Design Retrospective cohort of patients ≥18 years with chronic-phase CML treated with imatinib for at least 12 months. The primary objective was to explore the accumulate incidence of DMR and analyze the following variables: age, gender, Sokal risk, variant of the BCR/ABL1 transcript, imatinib exposure time, body mass index (BMI) and albumin and its association with the achievement of DMR. Results Ninety-six patients with a mean follow-up of 8 years were analyzed. The cumulative rate of DMR at the last follow-up was 65.62%, and the median time to document DMR was 63.13 months. The clinical and molecular variables were compared among three groups of response: no major molecular response (NO MMR), major molecular response (MMR), and DMR; the median age was 44.36, 35, and 42.87 years (p= 0.25); the median BMI was 27.71, 26.69 and 27.53 kg/m2 (p= 0.91); the median concentration of albumin was 4.18, 3.95, and 3.93 g/dL (p= 0.22); and the median time of exposure to imatinib was 63.82, 101.2, and 114.7 months (p= 0.0001). respectively. Patients with a high Sokal risk were associated with a lower incidence of MMR and DMR compared with a low risk (27.27% vs. 54.54% and 20.63 vs. 50.7%, respectively, p=0.007). The proportion of patients with a known transcript (incidence of e14a2 variant) was higher than e13a2 (31.25% vs 23.95%) but without statistically significant differences between the groups (p=0.99). Conclusions Incidence of DMR to imatinib exposure in our population is similar and even higher than reported in the literature regarding the several available data. The above findings, despite not following strict molecular monitoring, suggests that molecular monitoring by qRT-PCR can be performed in a longer interval. In this study, the prolonged exposure time to imatinib and the low Sokal risk, were significantly associated with a deeper molecular response.