BCR-ABL1 transcript doubling time as a predictor for treatment-free remission failure after imatinib discontinuation in chronic myeloid leukaemia in chronic phase.

The doubling time (DT) of the BCR-ABL1 quantitative polymerase chain reaction (qPCR) transcript level reflects the re-growing fraction of leukaemic cells after discontinuation of tyrosine kinase inhibitor (TKI). The present study analyzed monthly DT within six months after imatinib discontinuation in 131 patients. Monthly DT was calculated as x = ln(2)/K, where x is the DT and K is the fold BCR-ABL1 change from the previous value divided by the number of days between each measurement. The optimal DT value was determined as 12·75 days at two months using a recursive partitioning method. The patients were stratified into three groups: the high-risk group (DT<12·75 days but >0, with rapidly proliferating chronic myeloid leukaemia (CML) cells; n = 26) showed the lowest molecular relapse-free survival (mRFS) of 7·7% at 12 months, compared to 53·6% in the intermediate-risk group (DT≥12·75 days, with slowly proliferating CML cells; n = 16) or 90·0% in the low-risk group (DT≤0, i.e., without proliferating CML cells; n = 71; P < 0·001). Monthly assessment of DT helps identify high-risk patients for treatment-free remission failure with an imminent risk of molecular recurrence, and to define low-risk patients who can be spared the frequent monitoring of monthly molecular tests.

Kim DDH ，Kim TS ，Atenafu EG ，Novitzky Basso I ，Forrest D ，Bence-Bruckler I ，Savoie L ，Busque L ，Keating MM ，Delage R ，Xenocostas A ，Liew E ，Paulson K ，Stockley T ，Laneuville P ，Lipton JH ，Kamel-Reid S ，Leber B ... -  《-》

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

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. 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. 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. 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.

Nicolini FE ，Dulucq S ，Boureau L ，Cony-Makhoul P ，Charbonnier A ，Escoffre-Barbe M ，Rigal-Huguet F ，Coiteux V ，Varet B ，Dubruille V ，Lenain P ，Rousselot P ，Rea D ，Guerci-Bresler A ，Legros L ，Liu J ，Gardembas M ，Ianotto JC ，Turlure P ，Johnson-Ansah H ，Martiniuc J ，Jardel H ，Joly B ，Zunic P ，Henni T ，Villemagne B ，Berger MG ，Cayssials E ，Guilhot F ，Larosa F ，Guilhot J ，Etienne G ，Mahon FX ... -  《-》

BCR-ABL1 transcript at 3 months predicts long-term outcomes following second generation tyrosine kinase inhibitor therapy in the patients with chronic myeloid leukaemia in chronic phase who failed Imatinib.

The BCR-ABL1 transcript level at 3 months can predict long-term outcomes following frontline therapy with Imatinib or Dasatinib in chronic myeloid leukaemia (CML) patients. However, data is lacking for second-generation tyrosine kinase inhibitor (2GTKI) therapy after Imatinib failure. A total of 112 patients with CML in chronic phase receiving 2GTKI after Imatinib failure were reviewed. Treatment outcomes including complete cytogenetic (CCyR), major molecular (MMR) and molecular response 4.5 (4.5 log reduction of BCR-ABL1 transcript level, MR(4.5) ), treatment failure, progression-free and overall survival (OS) were compared according to BCR-ABL1 transcript levels at 3 or 6 months, divided into <1%(IS) , 1-10%(IS) and ≥ 10%(IS) . BCR-ABL1 transcript level at 3 months showed better correlation with OS (P < 0.001) than that at 6 months (P = 0.147). Better OS was also observed in the patients achieving <1%(IS) (100%) and 1-10%(IS) (100%) than those with ≥ 10%(IS) at 3 months (70.6%, P < 0.001). Those with <1%(IS) showed the best CCyR, MMR and MR(4.5) rates; 1-10%(IS) , intermediate; and ≥ 10%(IS) , the lowest CCyR, MMR and MR(4.5) rates. The group with <1%(IS) at 3 months maintained significantly lower BCR-ABL1 transcript level compared to other two groups. In conclusion, the BCR-ABL1 transcript level at 3 months is the most relevant surrogate for outcomes following 2GTKI therapy after Imatinib failure.

Kim DD ，Lee H ，Kamel-Reid S ，Lipton JH ... -  《-》

Dasatinib rapidly induces deep molecular response in chronic-phase chronic myeloid leukemia patients who achieved major molecular response with detectable levels of BCR-ABL1 transcripts by imatinib therapy.

Shiseki M ，Yoshida C ，Takezako N ，Ohwada A ，Kumagai T ，Nishiwaki K ，Horikoshi A ，Fukuda T ，Takano H ，Kouzai Y ，Tanaka J ，Morita S ，Sakamoto J ，Sakamaki H ，Inokuchi K ... -  《-》

A prospective analysis of clinical efficacy and safety in chronic myeloid leukemia-chronic phase patients with imatinib resistance or intolerance as evaluated using European LeukemiaNet 2013 criteria.

We conducted a phase II study to evaluate the efficacy and safety of dasatinib in Japanese patients with imatinib-resistant or imatinib-intolerant chronic myeloid leukemia (CML). From 2009 to 2011, 54 CML-chronic phase (CP) patients with resistance (n = 40) or intolerance (n = 25) to imatinib were registered to undergo dasatinib treatment. Eleven patients showed both resistance and intolerance to imatinib. Coincidentally, the resistance criteria in this study were the same as a non-optimal response to tyrosine kinase inhibitors (TKIs) as defined in the European LeukemiaNet (ELN) 2013 recommendations. The overall incidence rate of major molecular response (MMR) at 12 months was 62.3% (n = 47). Forty patients with resistance to imatinib who were 'warning' and 'failure' patients based on the ELN 2013 recommendations were assessed; cumulative MMR and MR(4.5) rates were 62.5% (n = 39) and 21.0% (n = 40), respectively, at 12 months. Twelve patients who showed a BCR-ABL transcript level >1% on the international scale did not achieve a MMR or discontinued dasatinib treatment because of insufficient effects. With regard to safety issues, grade 3/4 non-hematologic adverse events (AEs) were infrequent. Patients with non-optimal responses (who meet ELN 2013 warning and failure criteria) to imatinib should be switched quickly to dasatinib, which is less toxic in CML-CP patients, to improve their prognoses. A BCR-ABL1 IS of <1% at 3 months of dasatinib administration is a landmark for good therapeutic outcome.

Murai K ，Akagi T ，Shimosegawa K ，Sugawara T ，Ishizawa K ，Ito S ，Murai K ，Motegi M ，Yokoyama H ，Noji H ，Tajima K ，Kimura J ，Chou T ，Ogawa K ，Harigae H ，Kubo K ，Oba K ，Sakamoto J ，Ishida Y ... -  《-》