Dasatinib synergizes with doxorubicin to block growth, migration, and invasion of breast cancer cells

Background:

Src family kinases control multiple cancer cell properties including cell cycle progression, survival, and metastasis. Recent studies suggest that the Src inhibitor dasatinib blocks these critical cancer cell functions.

Methods:

Because the molecular mechanism of action of dasatinib in breast cancers has not been investigated, we evaluated the effects of dasatinib as a single agent and in combination with the commonly used chemotherapeutic doxorubicin, on the proliferation, viability, and invasive capacity of breast cancer cells lines earlier categorised as dasatinib-sensitive (MDA-MB-231) and moderately resistant (MCF7 and T47D). We also tested the effects of these drugs on the actin cytoskeleton and associated signalling pathways.

Results:

The cell lines tested varied widely in sensitivity to growth inhibition (IC₅₀=0.16–12.3 μM), despite comparable Src kinase inhibition by dasatinib (IC₅₀=17–37 nM). In the most sensitive cell line, MDA-MB-231, dasatinib treatment induced significant G₁ accumulation with little apoptosis, disrupted cellular morphology, blocked migration, inhibited invasion through Matrigel (P<0.01), and blocked the formation of invadopodia (P<0.001). Importantly, combination treatment with doxorubicin resulted in synergistic growth inhibition in all cell lines and blocked the migration and invasion of the highly metastatic, triple-negative MDA-MB-231 cell line.

Conclusion:

The observed synergy between dasatinib and doxorubicin warrants the re-evaluation of dasatinib as an effective agent in multi-drug regimens for the treatment of invasive breast cancers.     

Dasatinib dose management for the treatment of chronic myeloid leukemia

Chronic myeloid leukemia (CML) has evolved into a chronic disease that is managed with tyrosine kinase inhibitor therapy. Now that long‐term survival has been achieved in patients with CML, the focus of treatment has shifted to dose optimization, with the goal of maintaining response while improving quality of life. In this review, the authors discuss optimizing the dose of the second‐generation tyrosine kinase inhibitor dasatinib. Once‐daily dosing regimens for dasatinib in the first and later lines of treatment were established through long‐term (5‐year and 7‐year) trials. Recently published data have indicated that further dose optimization may maintain efficacy while minimizing adverse events. Results obtained from dose optimization and discontinuation trials currently in progress will help practitioners determine the best dose and duration of dasatinib for patients with CML, because treatment decisions will be made through continued discussions between physicians and patients. Cancer 2018;124:1660‐72 . © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.     

Delayed methotrexate clearance in patients with acute lymphoblastic leukemia concurrently receiving dasatinib

We aimed to determine whether patients receiving dasatinib or imatinib concurrently with high‐dose methotrexate (HDMTX) had slower methotrexate clearance than patients not receiving a tyrosine kinase inhibitor (TKI) during the HDMTX infusion. Patients concurrently receiving dasatinib and HDMTX (N = 7) had significantly slower MTX clearance (P = 0.008) than patients not receiving a TKI (N = 111). Two patients receiving a TKI during a HDMTX infusion required glucarpidase. In vitro studies showed that dasatinib significantly inhibited methotrexate uptake by SLCO1B1‐expressing cells (P = 0.009). There may be an interaction between dasatinib and HDMTX, mediated by the transporter SLCO1B1, that causes a delay in MTX clearance.     

Dasatinib cessation after deep molecular response exceeding 2 years and natural killer cell transition during dasatinib consolidation

Tyrosine kinase inhibitors (TKI) improve the prognosis of patients with chronic myelogenous leukemia (CML) by inducing substantial deep molecular responses (DMR); some patients have successfully discontinued TKI therapy after maintaining DMR for ≥1 year. In this cessation study, we investigated the optimal conditions for dasatinib discontinuation in patients who maintained DMR for ≥2 years. This study included 54 patients with CML who were enrolled in a D‐STOP multicenter prospective trial, had achieved DMR, and had discontinued dasatinib after 2‐year consolidation. Peripheral lymphocyte profiles were analyzed by flow cytometry. The estimated 12‐month treatment‐free survival (TFS) was 62.9% (95% confidence interval: 48.5%‐74.2%). During dasatinib consolidation, the percentage of total lymphocytes and numbers of CD3⁻ CD56⁺ natural killer (NK) cells, CD16⁺ CD56⁺ NK cells and CD56⁺ CD57⁺ NK‐large granular lymphocytes (LGL) were significantly higher in patients with molecular relapse after discontinuation but remained unchanged in patients without molecular relapse for >7 months. At the end of consolidation, patients whose total lymphocytes comprised <41% CD3⁻ CD56⁺ NK cells, <35% CD16⁺ CD56⁺ NK cells, or <27% CD56⁺ CD57⁺ NK‐LGL cells had higher TFS relative to other patients (77% vs 18%; P < .0008; 76% vs 10%; P < .0001; 84% vs 46%; P = .0059, respectively). The increase in the number of these NK cells occurred only during dasatinib consolidation. In patients with DMR, dasatinib discontinuation after 2‐year consolidation can lead to high TFS. This outcome depends significantly on a smaller increase in NK cells during dasatinib consolidation.     

Effects of dasatinib on EphA2 receptor tyrosine kinase activity and downstream signalling in pancreatic cancer

Eph receptors constitute the largest family of receptor tyrosine kinases in the human genome. EphA2 is one prominent member that is overexpressed and functionally altered in many invasive cancers, including pancreatic cancer. Dasatinib, which is a multi-targeted kinase inhibitor mainly developed for Bcr-Abl and Src family kinases, has recently been shown to have significant activity against EphA2. As selective small molecule EphA2 inhibitors are not currently available, we investigated the therapeutic potential to target EphA2 by dasatinib in pancreatic cancer cell lines. Using in vitro kinase assays, we found that EphA2 receptor tyrosine kinase was inhibited directly by dasatinib in a dose-dependent manner. Stimulation with ephrinA1 produced rapid increases of EphA2 phosphorylation that were inhibited by dasatinib, although the effects on activation of downstream signalling differed among the pancreatic cancer cell lines. Dasatinib also inhibited ligand-induced binding of EphA2 to the ubiquitin ligase Cbl, and the internalisation and degradation of EphA2, suggesting that these processes are dependent on kinase activity. Treatment with dasatinib decreased EphA2 phosphorylation in BxPC-3 xenografts, suggesting that dasatinib might have activity in pancreatic cancer due to EphA2 inhibition, besides its effects on Src.     

达沙替尼原料药的晶型分析

建立片剂中达沙替尼原料药的晶型分析方法。使用X射线粉末衍射(XRPD)和固态核磁共振光谱(ssNMR),分别对达沙替尼市售片剂施达赛^®和依尼舒^®中达沙替尼原料药的晶型进行分析。结果显示,施达赛^®片剂中达沙替尼原料药为一水合物,而依尼舒^®片剂中达沙替尼原料药为无水晶型。在施达赛^®片剂中没有观察到无水晶型,而依尼舒^®片剂中没有观察到一水合物。XRPD与ssNMR两种方法检测结果一致,均可用于固体片剂中达沙替尼原料药的晶型分析。