Association between Germline Single-Nucleotide Variants in ADME Genes and Major Molecular Response to Imatinib in Chronic Myeloid Leukemia Patients

Imatinib is the most common first-line tyrosine kinase inhibitor (TKI) used to treat chronic-phase chronic myeloid leukemia (CP-CML). However, only a proportion of patients achieve major molecular response (MMR), so there is a need to find biological factors that aid the selection of the optimal therapeutic strategy (imatinib vs. more potent second-generation TKIs). The aim of this retrospective study was to understand the contribution of germline single-nucleotide variants (gSNVs) in the achievement of MMR with imatinib. In particular, a discovery cohort including 45 CP-CML patients was analyzed through the DMET array, which interrogates 1936 variants in 231 genes related to the absorption, distribution, metabolism and excretion (ADME) process. Variants statistically significant in the discovery cohort were then tested in an extended and independent cohort of 137 CP-CML patients. Finally, a total of 7 gSNVs (ABCG1-rs492338, ABCB11-rs496550, ABCB11-rs497692, CYP2D6-rs1135840, CYP11B1-rs7003319, MAT1A-rs4934027 and SLC22A1-rs628031) and one haplotype in the ABCB11 gene were significantly associated with the achievement of MMR with first-line imatinibtreatment. In conclusion, we identified a genetic signature of response to imatinib in CP-CML patients that could be useful in selecting those patients that may benefit from starting imatinib as first-line therapy, therefore avoiding the toxicity related to second-generation TKIs.

Feasibility of treatment discontinuation in chronic myeloid leukemia in clinical practice: results from a nationwide series of 236 patients

Over half of chronic myeloid leukemia (CML) patients in deep molecular response do not lose the major molecular response (MMR) after stopping treatment with tyrosine kinase inhibitors (TKI). This strategy is safe in clinical trials, but its applicability in the real-life setting remains unsettled. We describe the outcomes after TKI discontinuation in a nationwide series of 236 CML patients. Median follow-up from treatment discontinuation was 21.5 months and 5 patients died from CML-unrelated causes. TKI therapy was reinitiated due to MMR loss (n = 52), increase ≥ 1 log in BCR-ABL transcript level without losing MMR (n = 12), patient preference (n = 2), and withdrawal syndrome (n = 1). Treatment-free remission rate at 4 years was 64% (95% confidence interval, CI: 55%–72%). Cumulative incidence of molecular recurrence at 3 years was 33% (95% CI: 26%–38%). TKI treatment for < 5 years and MR4.5 duration shorter than 4 years were both associated with higher incidence of molecular recurrence. No patient had disease progression. Response status at last control was: MR4.5 (n = 196), MR4 (n = 15), MMR (n = 14), complete cytogenetic response (n = 10), and other (n = 1). A significant increase in Hb and cholesterol levels was observed after imatinib withdrawal. Our results demonstrate that TKI treatment discontinuation is feasible in real-life clinical practice.

[Comparison of two initial mobilizing strategies of peripheral blood stem cells for autologous transplantation in patients with lymphoma and human immunodeficiency virus infection]

BACKGROUND AND OBJECTIVE

Several studies have demonstrated the feasibility of autologous stem cell transplantation (ASCT) in patients with lymphoma and human immunodeficiency virus (HIV) infection. HIV infection has been described as a risk factor for poor mobilization. The aim of this study was to compare the results of two mobilization strategies of peripheral blood stem cells (PBSC) in patients with lymphoma and HIV infection in seven Spanish hospitals.

PATIENTS AND METHODS

The following variables were collected: demographic, clinical and biological features, previous chemotherapies and outcomes, as well as mobilization's strategies (classified in two groups: 1) G-CSF, and 2) G-CSF + chemotherapy).

RESULTS

Between January 2000 and May 2010, 42 patients with lymphoma and HIV infection were referred for ASCT. The rate of successful mobilization (collection >1.60 × 10(6) CD34 cells/kg) with the first regimen was 67%, with no differences between those patients mobilized with G-CSF or with G-CSF + chemotherapy (16 [72%] and 12 [60%], respectively; p=0.382). The status of the lymphoma at the time of mobilization was the only factor for successful mobilization (20/22 patients [91%] in complete remission [CR] mobilized adequately versus 5/12 [58%] in partial remission [PR]; p=0.038).

CONCLUSIONS

In patients with lymphoma and HIV infection, mobilization with G-CSF was as effective as mobilization with chemotherapy followed by G-CSF. The stage of disease prior to the mobilization was the main risk factor for the success of mobilization, with better results in patients mobilized in remission of the lymphoma.