[A multicenter study on the revalidation of validated conversion factor for the conversion of BCRABL（P210）transcript levels to the international scale in chronic myeloid leukemia]

[Analysis on tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia in the real world: experience from single center]

Objective: To explore status of tyrosine kinase inhibitor (TKI) discontinuation in patients with chronic myeloid leukemia (CML) in the chronic phase (CP) in the real world, to analyze causes, factors and outcomes associated with TKI discontinuation and the possibility of pursuit treatment-free remission (TFR) in China. Methods: From January 2013 to August 2016, data of CML-CP patients in Peking University People's Hospital which were not enrolled in clinical trials were retrospectively collected and analyzed. Results: Data of 662 CML-CP patients were collected. With a median follow-up after TKI-therapy of 26 months (range, 3-187 months) , 187 patients (28.2%) experienced TKI cessation of at least 2 weeks. Causes of TKI discontinuation included hematologic adverse events 57.8% (n=108) , non-hematologic adverse events 30.4% (n=57) , financial burden 25.1% (n=47) , and others 7.0% (n= 13) . Multivariate analyses showed female, ≥40 years, no co-morbidity, and interval from diagnosis to TKI initiation ≥6 months, TKI switch and patients from other hospitals were factors associated with TKI discontinuation because of hematologic adverse effects. Female and patients from other hospitals were factors associated with TKI discontinuation because of non-hematologic adverse effect. TKI switch, generic TKI used and patients from other hospitals were factors associated with TKI discontinuation because of financial toxicity. Patients TKI discontinuation because of hematologic, non-hematologic or financial toxicity achieved a lower complete cytogenetic response or complete molecular response (CMR) than those with uninterrupted TKI-therapy. Patients with TKI discontinuation because of hematologic or financial toxicity had a shorter progression-free survival than those with uninterrupted TKI-therapy. 5 of 7 patients who obtained sustained CMR and discontinued TKI-therapy experienced disease recurrence with a median duration of 3 months (range, 2-32 months) . In 39 patients from other hospitals who aimed to confirm their optimal response of sustained CMR in Peking University People's Hospital, 21 (53.8%) were BCR-ABL positive. Conclusion: In the real world in China, half of CML-CP patients who discontinued TKI-therapy were incurred to TKI-related hematologic adverse effect, and both a quarter of them, TKI-related non-hematologic toxicities and financial toxicity, respectively. Discontinued TKI-therapy due to hematologic adverse events or financial toxicity was associated with lower TKI-therapy response rates. Nowadays, based on the Chinese situation, it is too early to talk about TFR.

[The establishment and application of internal quality control system for real-time quantitative PCR detection of BCR-ABL (P210) transcript levels]

Objective: To set internal quality control system of BCR-ABL (P210) transcript levels for real-time quantitative PCR (RQ-PCR). Methods: Using K562 cells and HL-60 cells, we prepared high- and low-level BCR-ABL internal quality control substance. The BCR-ABL (P210) transcript levels of internal quality control substance have been determined for 184 times together with clinical samples from August 2013 to October 2015. The slope rate, intercept and correlation coefficient of standard curve were calculated according to different reagent lots (lots number 20130303, 20131212, 20140411 and 20150327 are called R1、R2、R3 and R4 for short respectively), and the detection results of quality control substance were calculated according to different reagent lots and quality control substance lots (lots number 20130725, 20140611 are called Q1、Q2 for short respectively). Then the results were analyzed by Levey-Jennings quality control chart combined with Westgard multi-rules theory. Results: ①We analyzed the slope rate and intercept of standard curve. Fifty-three times of the R1 reagent detection, 80 times of the R3 reagent detection and 14 times of the R4 reagent detection were all under control. For 37 times detection of R2 reagent, the slope rate was out of control for 6 times. It was lower than x-s for the 2-8 tests and upper the average for the 12-37 tests. The intercept was out of control for 9 times, upper the x+s for the 1-8 tests and lower the average for the 12-37 tests. ② According to the detection results of quality control substance, for Q1 quality control substance, 49 tests by R1 reagent were under control, and 1 out of 23 tests by R2 reagent was out of control. For Q2 quality control substance, 14 tests by R2 reagent detection, 72 tests by R3 reagent detection and 14 tests by R4 reagent were all under control. Conclusion: The preparation of high- and low-level quality control substance using K562 and HL-60 cells was convenient and the detection results were reliable and stable. The application of quality control substance combined with slope rate and intercept in the internal quality control may contribute to quality assurance for quantitative detection of BCR-ABL (P210) transcript levels.