Switching to nilotinib is associated with deeper molecular responses in chronic myeloid leukemia chronic phase with major molecular responses to imatinib: STAT1 trial in Japan

[Observational study of chronic myeloid leukemia Chinese patients who discontinued tyrosine kinase inhibitors in the real-world]

Objective: This study aimed to observe whether the treatment-free remission (TFR) of second-generation tyrosine kinase inhibitors (TKI) in chronic myeloid leukemia (CML) is better than imatinib (IM) . Methods: The clinical data of 274 CML patients who discontinued treatment and with complete clinical data were retrospectively studied from June 2013 to March 2021. Using both univariate and multivariate Cox proportional hazards regression models, risk factors influencing TFR outcomes after drug withdrawal in CML patients were assessed. Results: A total of 274 patients were enrolled, 140 patients were women (51.1%) , with a median age of 48 (9-84) years at the time of TKI discontinuation. Prior to TKI discontinuation, 172 (62.8%) patients were treated with IM, and 102 (37.2%) had received second-generation TKI treatment, including 73 patients who had shifted from IM to a second-generation TKI and 29 patients who used second-generation TKI as the first-line treatment. The rationale for converting to a second-generation TKI are as follows: 37 patients aimed deep molecular response (DMR) to achieve TFR, seven patients changed due to IM intolerance, and 29 patients changed because of failure to achieve the optimal treatment response. The use of the last type of TKI included 96 patients (94.1%) with nilotinib, three patients (2.9%) with dasatinib, and two patients (2%) with flumatinib, including one patient who changed to IM due to second-generation TKI intolerance. No statistical differences were found in the median age at diagnosis and TKI discontinuation, sex, Sokal score, IFN treatment before TKI, median time of TKI treatment to achieve DMR, and the reasons for TKI discontinuation between the second TKI and IM (P>0.05) .The median cumulative treatment time of TKI (71.5 months vs 88 months, P<0.001) , the last TKI median treatment time (60 months vs 88 months, P<0.001) , and the median duration of DMR (58 months vs 66 months, P=0.002) were significantly shorter in the second-generation TKI compared with IM. In the median follow-up of 22 (6-118) months after TKI discontinuation, 88 patients (32.1%) had lost their MMR at a median of 6 (1-91) months; of the 53 patients (60.2%) who lost MMR within 6 months, the overall TFR rate was 67.9%, and the cumulative TFR rates at 12 and 24 months were 70.5% and 67.5%, respectively. Withdrawal syndrome occurred in 26 patients (9.5%) . For patients who restarted TKI treatment, 72 patients (83.7%) achieved DMR again at a median treatment of 4 (1 to 18) months. The univariate analysis showed that the TFR rate of patients treated with second-generation TKI was significantly higher than those who were treated with IM (77.5% vs 62.2%, P=0.041) . A further subgroup analysis found that the TFR rate of the second-generation TKI patients was significantly higher than those treated with IM (80.8% vs 62.2%, P=0.026) . No significant difference was found in the second-generation TKI used as the first line treatment compared with those who were treated with IM (69.0% vs 62.2%, P=0.599) . The multivariate analysis results showed that second-generation TKI treatment was an independent prognostic factor affecting TFR in patients who discontinued TKI (RR=1.827, 95%CI 1.015-3.288, P=0.044) . Conclusion: In the clinical setting, more CML patients rapidly achieved TFR using second-generation TKI than IM treatment.

Pharmacological Effects of Polyphenol Phytochemicals on the JAK-STAT Signaling Pathway

The JAK-STAT signaling pathway is a common pathway of many cytokine signal transductions, closely related to cell proliferation, apoptosis, differentiation, and inflammatory response. It is essential for inhibiting the inflammatory response, initiating innate immunity, and coordinating adaptive immune mechanisms. Owing to the nature of this pathway and its potential cross-epitopes with multiple alternative pathways, the long-term efficacy of monotherapy-based adaptive targeting therapy is limited, and the majority of drugs targeting STATs are still in the preclinical phase. Meanwhile, curcumin, quercetin, and several kinds of plant polyphenol chemicals play roles in multiple sites of the JAK-STAT pathway to suppress abnormal activation. Polyphenol compounds have shown remarkable effects by acting on the JAK-STAT pathway in anti-inflammatory, antitumor, and cardiovascular disease control. This review summarizes the pharmacological effects of more than 20 kinds of phytochemicals on JAK-STAT signaling pathway according to the chemical structure of polyphenolic phytochemicals.

The BCRP inhibitor febuxostat enhances the effect of nilotinib by regulation of intracellular concentration

Nilotinib is a substrate of the breast cancer resistance protein (BCRP), which is a drug efflux transporter encoded by ABCG2 and regulates the pharmacokinetics of its substrates. We investigated the interaction between nilotinib and BCRP in chronic myeloid leukemia (CML) cells. An imatinib-resistant K562 cell line (K562/IM-R) treated with nilotinib was analyzed for BCRP expression, proliferation, apoptosis, and intracellular nilotinib concentration. K562/IM-R cells cultured with tyrosine kinase inhibitors (TKIs) showed an increased cell count and retained viability, whereas the growth of parental K562 cells was severely inhibited, suggesting that BCRP is involved in developing resistance to TKIs. Nilotinib-treated K562/IM-R cells showed a reduction in apoptosis; however, febuxostat pretreatment resulted in increased apoptosis. The intracellular concentration of nilotinib in K562/IM-R cells was significantly reduced compared to that in parental K562 cells, and febuxostat-pretreated K562/IM-R cells showed an increased intracellular nilotinib level compared to cells without pretreatment. The reduction in nilotinib levels caused by BCRP in CML cells might play a crucial role in resistance to TKIs. Moreover, febuxostat, as a BCRP inhibitor, could enhance nilotinib sensitivity, and combination therapy with nilotinib and febuxostat may represent a promising strategy for treatment of CML.

Treatment-free remission after two-year consolidation therapy with nilotinib in patients with chronic myeloid leukemia: STAT2 trial in Japan

The purpose of this trial was to evaluate the efficacy of 2-year consolidation therapy with nilotinib, at a dose of 300 mg twice daily, for achieving treatment-free remission in chronic myeloid leukemia patients with a deep molecular response (BCR-ABL1^IS ≤0.0032%). Successful treatment-free remission was defined as no confirmed loss of deep molecular response. We recruited 96 Japanese patients, of whom 78 sustained a deep molecular response during the consolidation phase and were therefore eligible to discontinue nilotinib in the treatment-free remission phase; of these, 53 patients (67.9%; 95% confidence interval: 56.4–78.1%) remained free from molecular recurrence in the first 12 months. The estimated 3-year treatment-free survival was 62.8%. Nilotinib was readministered to all patients (n=29) who experienced a molecular recurrence during the treatment-free remission phase. After restarting treatment, rapid deep molecular response returned in 25 patients (86.2%), with 50% of patients achieving a deep molecular response within 3.5 months. Tyrosine kinase inhibitor withdrawal syndrome was reported in 11/78 patients during the early treatment-free remission phase. The treatment-free survival curve was significantly better in patients with undetectable molecular residual disease than in patients without (3-year treatment-free survival, 75.6 versus 48.6%, respectively; P=0.0126 by the log-rank test). There were no significant differences in treatment-free survival between subgroups based on tyrosine kinase inhibitor treatment before the nilotinib consolidation phase, tyrosine kinase inhibitor-withdrawal syndrome, or absolute number of natural killer cells. The results of this study indicate that it is safe and feasible to stop tyrosine kinase inhibitor therapy in patients with chronic myeloid leukemia who have achieved a sustained deep molecular response with 2 years of treatment with nilotinib. This study was registered with UMIN-CTR (UMIN000005904).