Kinetics of early and late molecular recurrences after first-line imatinib cessation in chronic myeloid leukemia: updated results from the STIM2 trial.

Discontinuation of tyrosine kinase inhibitors in chronic phase chronic myeloid leukemia is feasible in clinical practice based on recently published international recommendations. Nevertheless, factors predictive of molecular recurrence have not been fully elucidated and long-term follow-up of patients enrolled in clinical studies are required in order to update knowledge on discontinuation attempts particularly in terms of the safety and durability of treatment-free remission (TFR). In the current study, we updated results from the STIM2 study in the light of the consensual criterion of molecular recurrence reported in different international recommendations. Among the 199 patients included in the perprotocol study, 108 patients lost a major molecular response. With a median follow-up of 40.8 months (5.5-111 months), the probability of treatment-free remission was 43.4% [36.3-50.4] at 5 years, 40.9% [32.8-47.3] at 7 years and 34.5% [25.6- 43.3] at 9 years. Molecular recurrence occurred between 0 to 6 months, 6 to 24 months and after 24 months in 75 patients (69%), 15 patients (14%) and 18 patients (17%), respectively. Notably, the kinetics of molecular recurrence differed significantly between these three subgroups with a median time from loss of MR4 (BCR::ABL1 IS≤0.01%) to loss of major molecular response of 1, 7 and 22 months, respectively. Predictive factors of molecular recurrence differed according to the time of occurrence of the molecular recurrence. Durations of imatinib treatment and deep molecular response as well as BCR::ABL1/ABL1 levels at cessation of tyrosine kinase inhibitor treatment, as quantified by reverse transcriptase droplet digital polymerase chain reaction, are involved in molecular recurrence occurring up to 24 months but not beyond. (ClinicalTrial. gov Identifier NCT#0134373).

Evaluation of Residual Disease and TKI Duration Are Critical Predictive Factors for Molecular Recurrence after Stopping Imatinib First-line in Chronic Phase CML Patients.

PURPOSE: Tyrosine kinase inhibitor (TKI) discontinuation is an emerging goal in chronic myelogenous leukemia (CML) management and several studies have demonstrated the feasibility of safely stopping imatinib. A sustained deep molecular response on long-term TKI is critical prior to attempting treatment-free remission. Reproducible results from several studies reported recently, failed to identify robust and reproducible predictive factors for the selection of the best candidates for successful TKI cessation. PATIENTS AND METHODS: We conducted a prospective national phase II study evaluating the cessation of imatinib after at least 2 years of MR4.5 obtained on imatinib first-line in patients with chronic phase CML. RESULTS: A total of 218 patients with de novo chronic phase CML were involved in the study. The median follow-up after imatinib cessation was 23.5 (1-64) months, 2 patients died from unrelated causes, and 107 experienced a confirmed increase in BCR-ABL1 levels defined as molecular recurrence. The molecular recurrence-free survival was 52% [95% confidence interval (CI), 45%-59%] at 6 months, and 50% (95% CI, 43%-57%) at 24 months. Droplet digital PCR (ddPCR) was used to evaluate more accurately low levels of BCR-ABL1 in 175 of 218 patients at imatinib cessation. To apply positive BCR-ABL1/ABL1 ratios on the international scale (IS), a conversion factor was calculated for ddPCR and the significant cut-off point was established at 0.0023%IS. In a multivariate analysis, the duration of TKI (≥74.8 months) and ddPCR (≥0.0023%IS) were the two identified predictive factors of molecular recurrence, with P = 0.0366 (HR, 0.635; 95% CI, 0.415-0.972] and P = 0.008 (HR, 0.556; 95% CI, 0.360-0.858), respectively. CONCLUSIONS: We conclude that the duration of TKI and residual leukemic cell load as determined by ddPCR are key factors for predicting successful treatment-free remission for patients with de novo chronic phase CML.See related commentary by Yan et al., p. 6561.

Persistent chronic inflammation and infection by Chikungunya arthritogenic alphavirus in spite of a robust host immune response.

Alphaviruses, including Chikungunya virus (CHIKV), produce a transient illness in humans, but severe forms leading to chronic incapacitating arthralgia/arthritis have been reported by mechanisms largely ill-characterized. The pathogenesis of CHIKV was addressed in a prospective cohort study of 49 hospitalized patients from Reunion Island subsequently categorized into two distinct groups at 12 mo postinfection. Comprehensive analyses of the clinical and immunological parameters throughout the disease course were analyzed in either the "recovered" or the "chronic" groups to identify prognostic markers of arthritis-like pathology after CHIKV disease. We found that the chronic group consisted mainly of more elderly patients (>60 y) and with much higher viral loads (up to 10(10) viruses per milliliter of blood) during the acute phase. Remarkably, a rapid innate immune antiviral response was demonstrated by robust dendritic/NK/CD4/CD8 cell activation and accompanied by a rather weak Th1/Th2 cytokine response in both groups. Interestingly, the antiviral immune response witnessed by high levels of IFN-alpha mRNA in PBMCs and circulating IL-12 persisted for months only in the chronic group. CHIKV (RNA and proteins) was found in perivascular synovial macrophages in one chronic patient 18 mo postinfection surrounded by infiltrating NK and T cells (CD4(++) but rare cytotoxic CD8). Fibroblast hyperplasia, strong angiogenesis, tissue lesions given the high levels of matrix metalloproteinase 2, and acute cell death [high cleaved poly(ADP-ribose) polymerase staining] were observed in the injured synovial tissue. These observed cellular and molecular events may contribute to chronic arthralgia/arthritis targeted by methotrexate used empirically for effective treatment but with immunosuppressive function in a context of viral persistence.