Many tyrosine kinase inhibitors (TKI) undergo extensive hepatic metabolism, but mechanisms of their hepatocellular uptake remain poorly understood. We hypothesized that liver uptake of TKIs is ...mediated by the solute carriers OATP1B1 and OATP1B3.
Transport of crizotinib, dasatinib, gefitinib, imatinib, nilotinib, pazopanib, sorafenib, sunitinib, vandetanib, and vemurafenib was studied in vitro using artificial membranes (PAMPA) and HEK293 cell lines stably transfected with OATP1B1, OATP1B3, or the ortholog mouse transporter, Oatp1b2. Pharmacokinetic studies were conducted with Oatp1b2-knockout mice and humanized OATP1B1- or OATP1B3-transgenic mice.
All 10 TKIs were identified as substrates of OATP1B1, OATP1B3, or both. Transport of sorafenib was investigated further, as its diffusion was particularly low in the PAMPA assay (<4%) than other TKIs that were transported by both OATP1B1 and OATP1B3. Whereas Oatp1b2 deficiency in vivo had minimal influence on parent and active metabolite N-oxide drug exposure, plasma levels of the glucuronic acid metabolite of sorafenib (sorafenib-glucuronide) were increased more than 8-fold in Oatp1b2-knockout mice. This finding was unrelated to possible changes in intrinsic metabolic capacity for sorafenib-glucuronide formation in hepatic or intestinal microsomes ex vivo. Ensuing experiments revealed that sorafenib-glucuronide was itself a transported substrate of Oatp1b2 (17.5-fold vs. control), OATP1B1 (10.6-fold), and OATP1B3 (6.4-fold), and introduction of the human transporters in Oatp1b2-knockout mice provided partial restoration of function.
These findings signify a unique role for OATP1B1 and OATP1B3 in the elimination of sorafenib-glucuronide and suggest a role for these transporters in the in vivo handling of glucuronic acid conjugates of drugs.
FLT3 kinase internal tandem duplication (ITD) mutations are common in acute myeloid leukemia (AML) and are associated with poor clinical outcomes. Although initial responses to FLT3 tyrosine kinase ...inhibitors (TKIs) are observed in FLT3-ITD−positive patients, subsequent relapse often occurs upon acquisition of secondary FLT3 kinase domain (KD) mutations, primarily at residues D835 and F691. Using biochemical assays, we determined that crenolanib, a novel TKI, demonstrates type I properties and is active against FLT3 containing ITD and/or D835- or F691-activating mutations. Potent activity was observed in FLT3-ITD−positive AML cell lines. Crenolanib delayed the outgrowth of MV4-11 cells in a xenograft mouse model, whereas in combination with the type II TKI sorafenib, a significant decrease in leukemic burden (P < .001) and prolonged survival (P < .01) was observed compared with either type I or II TKI alone. Crenolanib was active against Ba/F3 cells harboring FLT3-ITD and secondary KD mutations and sorafenib-resistant MOLM-13 cells containing FLT3-ITD/D835Y both in vitro and in vivo. In addition, crenolanib inhibited drug-resistant AML primary blasts with FLT3-ITD and D835H/Y mutations. These preclinical data demonstrate that crenolanib is effective against FLT3-ITD containing secondary KD mutations, suggesting that crenolanib may be a useful therapeutic agent for TKI-naive and drug-resistant FLT3-ITD−positive AML.
•The tyrosine kinase inhibitor crenolanib has type 1 inhibitor properties and has potent activity against FLT3-activating mutations.•Crenolanib is active in vitro and in vivo against FLT3 inhibitor-resistant FLT3-ITD/D835 mutations.
The activity of imatinib in leukemia has recently been linked with expression of the organic cation transporter 1 (OCT1) gene SLC22A1. Here, we characterized the contribution of solute carriers to ...imatinib transport in an effort to further understand mechanisms involved in the intracellular uptake and retention (IUR) of the drug.
IUR of 3Himatinib was studied in Xenopus laevis oocytes and HEK293 cells expressing OATP1A2, OATP1B1, OATP1B3, OCT1-3, OCTN1-2, or OAT1-3. Gene expression was determined in nine leukemia cell lines using the Affymetrix U133 array.
Imatinib was not found to be a substrate for OCT1 in oocytes (P = 0.21), whereas in HEK293 cells IUR was increased by only 1.20-fold relative to control cells (P = 0.002). Furthermore, in 74 cancer patients, the oral clearance of imatinib was not significantly altered in individuals carrying reduced-function variants in SLC22A1 (P = 0.99). Microarray analysis indicated that SLC22A1 was interrelated with gene expression of various transporters, including ABCB1, ABCC4, ABCG2 (negative), and OATP1A2 (positive). Imatinib was confirmed to be a substrate for the three efflux transporters (P < 0.05) as well as for OATP1A2 (P = 0.0001).
This study suggests that SLC22A1 expression is a composite surrogate for expression of various transporters relevant to imatinib IUR. This observation provides a mechanistic explanation for previous studies that have linked SLC22A1 with the antitumor activity of imatinib. Because of its high expression in the intestine, ciliary body, gliomas, and leukemia cells, OATP1A2 may play a key role in imatinib pharmacokinetics-pharmacodynamics.
The use of multikinase inhibitors (MKI) in oncology, such as sorafenib, is associated with a cutaneous adverse event called hand-foot skin reaction (HFSR), in which sites of pressure or friction ...become inflamed and painful, thus significantly impacting quality of life. The pathogenesis of MKI-induced HFSR is unknown, and the only available treatment options involve dose reduction or discontinuation of therapy, which have negative effects on primary disease management. To investigate the underlying mechanisms by which sorafenib promotes keratinocyte cytotoxicity and subsequent HFSR induction, we performed a transporter-directed RNAi screen in human epidermal keratinocytes and identified SLC22A20 (OAT6) as an uptake carrier of sorafenib. Further investigations into the intracellular mechanism of sorafenib activity through in situ kinome profiling identified the mitogen-activated protein kinase MAP3K7 (TAK1) as a target of sorafenib that induces cell death. Finally, we demonstrate that sorafenib induced keratinocyte injury in vivo and that this effect could be reversed by cotreatment with the OAT6 inhibitor probenecid. Collectively, our findings reveal a novel pathway that regulates the entry of some MKIs into keratinocytes and explains the basis underlying sorafenib-induced skin toxicity, with important implications for the therapeutic management of HFSR.
Improvement in survival has been achieved for children and adolescents with AML but is largely attributed to enhanced supportive care as opposed to the development of better treatment regimens. High ...risk subtypes continue to have poor outcomes with event free survival rates <40% despite the use of high intensity chemotherapy in combination with hematopoietic stem cell transplant. Here we combine high-throughput screening, intracellular accumulation assays, and in vivo efficacy studies to identify therapeutic strategies for pediatric AML. We report therapeutics not currently used to treat AML, gemcitabine and cabazitaxel, have broad anti-leukemic activity across subtypes and are more effective relative to the AML standard of care, cytarabine, both in vitro and in vivo. JAK inhibitors are selective for acute megakaryoblastic leukemia and significantly prolong survival in multiple preclinical models. Our approach provides advances in the development of treatment strategies for pediatric AML.
Acute myeloid leukemia (AML) is a heterogeneous and complex disease, and treatments for this disease have not been curative for the majority of patients. In younger patients, internal tandem ...duplication of FLT3 (FLT3-ITD) is a common mutation for which two inhibitors (midostaurin and gilteritinib) with varied potency and specificity for FLT3 are clinically approved. However, the high rate of relapse or failed initial response of AML patients suggests that the addition of a second targeted therapy may be necessary to improve efficacy. Using an unbiased large-scale CRISPR screen, we genetically identified BCL2 knockout as having synergistic effects with an approved FLT3 inhibitor. Here, we provide supportive studies that validate the therapeutic potential of the combination of FLT3 inhibitors with venetoclax in vitro and in vivo against multiple models of FLT3-ITD-driven AML. Our unbiased approach provides genetic validation for co-targeting FLT3 and BCL2 and repurposes CRISPR screening data, utilizing the genome-wide scope toward mechanistic understanding.
Purpose
Investigate antileukemic activity of artemisinins, artesunate (ART), and dihydroartemisinin (DHA), in combination with cytarabine, a key component of acute myeloid leukemia (AML) chemotherapy ...using in vitro and in vivo models.
Methods
Using ten human AML cell lines, we conducted a high-throughput screen to identify antimalarial agents with antileukemic activity. We evaluated effects of ART and DHA on cell viability, cytotoxicity, apoptosis, lysosomal integrity, and combination effects with cytarabine in cell lines and primary patient blasts. In vivo pharmacokinetic studies and efficacy of single-agent ART or combination with cytarabine were evaluated in three xenograft models.
Results
ART and DHA had the most potent activity in a panel of AML cell lines, with selectivity toward samples harboring
MLL
rearrangements and
FLT3
-ITD mutations. Combination of ART or DHA was synergistic with cytarabine. Single-dose ART (120 mg/kg) produced human equivalent exposures, but multiple dose daily administration required for in vivo efficacy was not tolerated. Combination treatment produced initial regression, but did not prolong survival in vivo.
Conclusions
The pharmacology of artemisinins is problematic and should be considered in designing AML treatment strategies with currently available agents. Artemisinins with improved pharmacokinetic properties may offer therapeutic benefit in combination with conventional therapeutic strategies in AML.
Long non-coding ribonucleic acids (RNAs) are a novel class of RNA molecules, which are increasingly recognized as important molecular players in solid and hematologic malignancies. Herein we ...investigated whether long non-coding RNA expression is associated with clinical and molecular features, as well as outcome of younger adults (aged <60 years) with
cytogenetically normal acute myeloid leukemia. Whole transcriptome profiling was performed in a training (n=263) and a validation set (n=114). Using the training set, we identified 24 long non-coding RNAs associated with event-free survival. Linear combination of the weighted expression values of these transcripts yielded a prognostic score. In the validation set, patients with high scores had shorter disease-free (
<0.001), overall (
=0.002) and event-free survival (
<0.001) than patients with low scores. In multivariable analyses, long non-coding RNA score status was an independent prognostic marker for disease-free (
=0.01) and event-free survival (
=0.002), and showed a trend for overall survival (
=0.06). Among multiple molecular alterations tested, which are prognostic in cytogenetically normal acute myeloid leukemia, only double
mutations,
mutations and
-ITD associated with distinct long non-coding RNA signatures. Correlation of the long non-coding RNA scores with messenger RNA and microRNA expression identified enrichment of genes involved in lymphocyte/leukocyte activation, inflammation and apoptosis in patients with high scores. We conclude that long non-coding RNA profiling provides meaningful prognostic information in younger adults with cytogenetically normal acute myeloid leukemia. In addition, expression of prognostic long non-coding RNAs associates with oncogenic molecular pathways in this disease.
.
To compare side-by-side the uptake of sorafenib and sunitinib in vitro by human uptake solute carriers of the SLC22A and SLCO families, the transport by and inhibition of efflux ATP-binding cassette ...(ABC) transporters, and the role of ABCB1 in the plasma pharmacokinetics and brain penetration of these agents.
Uptake of (3)Hsorafenib or (3)Hsunitinib was assessed in Xenopus laevis oocytes or mammalian cells transfected with cDNAs coding for human OATP1A2, OATP1B1, OATP1B3, OCT1, OAT2, OAT3, OCTN1, or OCTN2. Efflux and inhibition experiments were conducted in cells transfected with human ABCB1, ABCG2, ABCC2, or ABCC4. In vivo pharmacokinetic studies were done in knockout mice lacking Abcb1-type transporters.
Intracellular uptake was not appreciably affected by any of the studied solute carriers and was minute relative to the respective prototypical substrates. Sorafenib and sunitinib showed concentration-dependent (1 and 10 micromol/L), low to moderate affinity for ABCB1 but were not affected by the other ABC transporters. Both agents inhibited all tested ABC transporters. The absence of Abcb1 had no affect on plasma pharmacokinetics, but brain penetration was moderately increased by 1.9- and 2.9-fold for sorafenib and sunitinib, respectively, in knockout animals versus controls.
Unlike other tyrosine kinase inhibitors, sorafenib and sunitinib do not appear to rely on active transport to enter the cell nor are they high-affinity substrates for ABC efflux transporters. Based on these characteristics, these two drugs may be less susceptible to transporter-mediated alterations in systemic exposure and transporter-related resistance mechanisms.
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