Focal adhesion kinase (FAK)

FAK phosphorylation at Tyr397 is inhibited by defactinib (VS-6063) in a dose- and time-dependent manner. Defactinib lowers AKT and YB-1 levels in taxane-resistant cell lines, according to RPPA findings. Defactinib dose-dependently and statistically significantly suppressed the expression of pFAK (Tyr397) in all cell lines. Within three hours, defactinib blocks the expression of pFAK (Tyr397), and within 48 hours, expression progressively returns [1].

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Effect of FAK Inhibition on Sensitivity to PTX [1]
We first tested the in vitro effects of Defactinib/VS-6063 on FAK phosphorylation. The expression of pFAK (Tyr397) was statistically significantly inhibited by VS-6063 in a dose-dependent manner in all cell lines (Figure 1A; Supplementary Figure 1A, available online). VS-6063 inhibited pFAK (Tyr397) expression within 3 hours, with a gradual return of expression by 48 hours (Figure 1B; Supplementary Figures 1B and 2, available online). Supplementary Figure 3 (available online) represents a typical experiment in which statistical analysis of triplicate experiments showed no statistically significant changes in FAK phosphorylation at the other residues tested (Tyr 576/577, Tyr 925, or Tyr 861). Because Pyk2 and FAK are approximately 60% identical in the central catalytic domain, we also tested Tyr402, Tyr 579/580, and Tyr 881 within PYK2. Phosphorylation inhibition of Tyr402 was observed only in the HeyA8 cells, with no phosphorylation residues changed in the HeyA8-MDR cell line after VS-6063 (1 µM) treatment for 1 hour.

VS-6063/Defactinib as a single agent (0–1 µM) did not affect the growth of any of the cells or their taxane-resistant counterparts (Supplementary Figure 4, available online). However, the combination of PTX and VS-6063 (1 µM) was more effective than either agent alone. PTX cytotoxicity was 2.1- to 4.9-fold greater in combination with VS-6063 compared with PTX alone (Figure 1C; Supplementary Figure 1C, available online). The combination effect of PTX and VS-6063 was evaluated with combination index by the Chou–Talalay method (20). Interactions between PTX and VS-6063 were synergistic in both HeyA8 and HeyA8-MDR cells (Figure 1D). Simultaneous exposure to doses of PTX and VS-6063 at ratios of 1:1000 for HeyA8 and 1:10 for HeyA8-MDR had a synergistic inhibitory effect on cell growth, with combination index values of 0.953 and 0.705, respectively. No synergy was noted between PTX and VS-6063 in SKOV3ip1 or SKOV3-TR cells, but an additive inhibitory effect on proliferation was noted (data not shown).

Next, we tested the effects of VS-6063/Defactinib based therapy on proliferation and apoptosis. Compared with PTX alone, the combination of VS-6063 (1 µM) with PTX (at the median inhibitory concentration [IC50] levels of PTX for the SKOV3 and HeyA8 cells of 8.5 and 6.3 nmol/L, respectively) decreased the proliferation rate in both taxane-sensitive and taxane-resistant cells (Figure 1E; Supplementary Figure 1D, available online). For apoptosis, the greatest effects were observed with combined PTX and VS-6063 (Figure 1F; Supplementary Figure 1E, available online). These findings suggest that VS-6063 in combination with PTX had at least an additive effect on both cell proliferation and apoptosis. PTX increased the proportion of the cell population in the G2 cell cycle fraction to 51.0% ± 0.4% in the HeyA8 cells compared with control (34.3% ± 0.3%; P < .001), and when combined with VS-6063 treatment, the percentage of cells in the G2 phase statistically significantly increased to 60.8% ± 0.9% (P < .001 compared with PTX). HeyA8-MDR cells were not arrested in G2 phase in either the PTX group or the combination group (P = .05) (Figure 1G; Supplementary Figure 1F, available online).

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Impact of FAK Inhibition on Downstream Signaling [1]
Because FAK is known to signal through beta 1 integrin, we first tested whether beta 1 integrin levels were affected by Defactinib/VS-6063, but no statistically significant changes were noted (Supplementary Figure 8, available online). To identify potential signaling pathways downstream of FAK in taxane-resistant cell lines, RPPAs were used and analyzed (DAVID Bioinformatics Resources; http://david.abcc.ncifcrf.gov/). In the VS-6063-treated group, 53 of the 161 proteins analyzed demonstrated a statistically significant change compared with the untreated group in both resistant cell lines (P < .05) (Figure 3A; Supplementary Table 1, available online). We found that the AKT pathway was the most involved pathway, including pFAK (Tyr 397), pAKT (Thr308), GSK-3 alpha/beta (Ser21/9), p27(T198), p70S6K (Thr389), PRAS40 (T246), and pYB-1(Ser102). Among these, pYB-1 (Ser102) was the most statistically significantly decreased protein (36.6% decreased by Defactinib/VS-6063 treatment; P < .001). Given the potential role of YB-1 in oncogenic and drug-resistance pathways, we focused on the potential relationship between FAK and YB-1 in subsequent studies.Figure 3B shows that PTX increased nuclear YB-1 expression, whereas PTX combined with VS-6063 decreased its expression in the HeyA8-MDR cells. Immunofluorescence studies also revealed similar findings (Figure 3C).

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FAK inhibition suppresses the malignant progression of ESCC cells [2]
Because FAK is hyperactivated in several ESCC cell lines, including KYSE150, KYSE180, KYSE30, KYSE410, KYSE450, KYSE510, Colo680, and KYSE70,9 we measured the growth inhibitory effect of Defactinib on these ESCC cell lines using MTS assay. As shown in Figure 1A, Defactinib treatment for 72 h dose-dependently decreased the viability of these indicated ESCC cell lines (Figure 1A). We further observed the anti-invasive or migratory ability of defactinib in KYSE410 and KYSE510 using Transwell assay. As shown in Figure 1B,C, defactinib dose-dependently inhibited the migration and invasion of indicated ESCC cells. Taken together, these results indicate that defactinib exerts excellent antitumor effects in ESCC cells. Next, FAK enhances the activity of PI3K/AKT pathway via interacting with PI3K catalytic subunit-p85. As shown in Figure 2E,F, defactinib dose-dependently disrupted the interaction between FAK and PI3K p85 subunit after 4 or 24 h treatment. In conclusion, the kinetics and magnitude of PI3K/AKT pathway inhibition suggest that this effect has an important role in the defactinib response.

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Effective inhibition of the downstream gene network by Defactinib [2]
To further understand molecular effects elicited by Defactinib treatment, we analyzed the transcriptomic profile of KYSE410 cells incubated with 10 μM defactinib from 4 to 24 h (Figure 3A), and focused on transcripts significantly downregulated in defactinib treatment. As shown in Figure 3B–J, strikingly, several target genes were substantially enriched in same functional sets, such as chemoresistance (Figure 3B), cell cycle (Figure 3C), growth factors, cytokines, and chemokines (Figure 3D), malignant progression (Figure 3E), cell plasticity (Figure 3F), heat shock protein family (Figure 3G), metabolism (Figure 3H), oncogene (Figure 3I), or transcriptional factors (Figure 3J), after 4 or 24 h defactinib treatment. A detailed analysis of representative genes involved in these functional sets suggested that many of these genes were sustained inhibition by defactinib after 4 or 24 h treatment (Table S1).

Within three hours, defactinib (VS-6063) at doses of 25 mg/kg twice day or more induced statistically significant suppression of pFAK (Tyr397), and within twenty-four hours, expression was restored. As a result, the dosage schedule for the ensuing treatment trials was determined to be Defactinib at 25 mg/kg twice day. In the course of the treatment trials, four groups of ten female nude mice with intraperitoneal HeyA8 tumors were randomly assigned: 1) oral administration of vehicle twice a day and weekly intraperitoneal injection of phosphate buffered saline (control); 2) Defactinib 25 mg/kg PO twice a day; 3) PTX weekly IP; and 4) VDefactinib 25 mg/kg PO twice a day. The HeyA8 model showed that PTX monotherapy reduced tumor weight by 87.4%, however combination therapy reduced tumor weight by the highest amount, 97.9% (P=0.05 compared with PTX). Tumor weight decreased in the combination therapy group in the SKOV3ip1 model by 92.7% as compared to PTX (P<0.001)[1].

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In Vivo Effects of VS-6063/Defactinib [1]
Defactinib/VS-6063 doses of 25mg/kg twice a day or greater statistically significantly inhibited pFAK (Tyr397) at 3 hours, with return of expression noted by 24 hours (Supplementary Figure 5, available online). Therefore, administration of Defactinib/VS-6063 at 25mg/kg twice a day was selected as the dosing schedule for subsequent therapy experiments. For therapy experiments, female nude mice bearing HeyA8 tumors in the peritoneal cavity were randomly divided into 4 groups (n = 10 per group): 1) vehicle orally twice daily and phosphate-buffered saline intraperitoneally weekly (control); 2) VS-6063/Defactinib 25mg/kg orally twice daily; 3) PTX intraperitoneally weekly; and 4) both VS-6063 25mg/kg orally twice daily and PTX intraperitoneally weekly. There was an 87.4% reduction in tumor weight by PTX monotherapy in the HeyA8 model, and combination therapy resulted in the greatest tumor weight reduction, with a 97.9% reduction (P = .05 compared with PTX) (Figure 2, A and B). In the SKOV3ip1 model, a 92.7% tumor weight reduction was observed in the combination group compared with PTX (P < .001).

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Defactinib is efficient for inhibition of tumor malignancy in vivo [2]
We further used three xenografted models, including subcutaneous tumor cell inoculation model (evaluation of tumor growth), popliteal lymph node metastasis model (evaluation of the lymph node metastatic ability of tumor cells), or lung colonization model (evaluation of metastatic ability of tumor cells), to comprehensively observe Defactinib-mediated antitumor effect in vivo. We subcutaneously inoculated KYSE410 and KYSE510 cells into the right flank of BALB/c mice. When xenografts reached approximately 100 mm3, we treated animals with defactinib (25 mg/kg/day, p.o.) for approximately 3 consecutive weeks and observed tumor growth. As shown in Figure 5A, after 2 weeks of treatment, tumor growth in defactinib group was significantly delayed, compared with control group. The tumor growth regression-mediated by defactinib was sustained to Week 3. Furthermore, after 3 weeks treatment, defactinib effectively blocked the activation of FAK in indicated tumor tissues (Figure S4). Results of popliteal lymph node metastasis model showed that FAK inhibition dramatically reduced the volume of ESCC cells in the lymph nodes from defactinib treatment group, compared with control group (Figure 5B). We further evaluated the effect of Defactinib on ESCC progression in a lung colonization model. Animals were intravenously injected with the indicated ESCC cells. As shown in Figure 5C, THE number of tumor nests in lungs from defactinib-treated group was significantly lower than that of control group. Results of Figure 5D showed that defactinib significantly extended the survival period of ESCC tumor-beared animals, compared with control treatment. IHC assay showed that dafactinib significantly decreased the expression of proliferation biomarker-Ki-67 (Figure 5E) and angiogenic biomarker-CD31 (Figure 5F) in indicated tumors. Importantly, histological analysis of heart, liver, spleen and kidney tissues showed no obvious alterations between control group and Defactinib treatment group, suggesting that defactinib did not produce significantly toxic effects on normal tissues (Figure 6A). Body weight between defactinib and control treatment groups was no apparent difference (Figure 6B).

Enzyme-linked immunosorbent assay analysis of nulcear factor-κB transcriptional activity [2]
Human nulcear factor-κB (NF-κB) p65 transcription factor activity assay kit was applied to evaluate the activity of NF-κB, according to the manufacturer's instructions. Briefly, nuclear extracts, DNA binding buffer, DTT, and transcriptional factor-activity assay reagent were added to 96-well (100 μl/well) for 2 h at room temperature. After washing four times with washing buffer, the 96-well plate was added with NF-κB p65 primary antibody solution (100 μl/well) for 1 h at room temperature. Then, horseradish peroxidase-conjugated secondary antibody, TMB one-step substrate reagent and stop solution were sequentially added. The optical denstiy value of NF-κB p65 activity was read at 450 nm using a microplate reader. The experiment was repeated five times.

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Microarray assay [2]
The Agilent SurePrint G3 human gene expression v3 8 × 60 K microarray was used to evaluate the changes of downstream genes. Briefly, total ribonucleic acid (RNA) of KYSE410 cells was extracted and transcribed to complementary deoxyribonucleic acid (cDNA). Then, cDNA was labeled with cyanine-3-CTP, hybridized with microarray, which was washed and scanned using the Agilent Scanner G2505C. The fluorescent intensity data were extracted with Feature Extraction software, and then Genespring as used to obtain the raw data. The threshold set for upregulated or downregulated genes was a fold change of ≥2 and a p value of  ≤.05.

In Vitro Gene Silencing [1]
YB-1 small interfering RNA (siRNA) 1 (target sequence 5′-CCUAUGGGCGUCGACCACA-3′) and siRNA2 (target sequence 5′-GUUCCAGUUCAAGGCAGUA-3′) and used to silence YB-1 expression in the ovarian cancer cell lines. A nonsilencing siRNA that did not share sequence homology with any known human mRNA from a Basic Local Alignment Search Tool (BLAST) search was used as control, as previously described.

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Western Blot Analysis [1]
Lysates from cultured cells was prepared as previously described. Typically, 30 μg of protein was fractionated by 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis and transferred to a nitrocellulose membrane. Additional details for immunoblotting are provided in the Supplementary Methods (available online).

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Cell Viability, Proliferation, and Apoptosis Assays [1]
Viability [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT)], proliferation (5-ethynil-2’-deoxyuridine), and apoptosis (annexin-V phycoerythrin [PE]/7AAD staining) assays were performed as previously described.

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Cell proliferation/viability assay [2]
The antiproliferative effect of Defactinib on ESCC cells was evaluated using 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) method. Briefly, 3 × 103 indicated cells in 100 μl of RPMI 1640 medium were seeded in 96-well plates. Twenty-four hours later, cells were attached and treated with different doses of Defactinib (0–25 μM) for 72 h. Then, the medium was discarded, and cells were incubated with MTS solution for 1 h. Plates were scanned spectrophotometrically at 490 nm, and the number of viable cells was positively correlated with the formazan product.

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Transwell migration/invasion assays [2]
Migration of cells was assayed using Transwell chamber systems with polycarbonate membrane inserts containing 8-μm pore size. The indicated ESCC cells (~1 × 105 cells) were seeded in the upper chamber with 200 μl FBS-free RPMI 1640 medium, and the lower chamber was added with 1 ml of RPMI 1640 medium with 20% FBS. After 24 h, the upper chambers were fixed in methanol for 10 min, stained with 2% crystal violet solution for 30 min, and the nonmigratory cells in the upper chamber were removed with cotton swabs. The migratory cells were then photographed under a microscope. The experiment was repeated five times. For the transwell invasion assay, the membrane of the upper chamber was precoated with 50 μl of 2.5 mg/ml matrigel solution. Other experimental conditions were similar to the migration assay.

Female BALB/c nude mice aged 4 weeks old were purchased from Beijing Vital River Laboratories and maintained under standard pathogen-free conditions. All animal experiment was conducted in accordance with the protocol approved by the Institutional Review Board of Peking University Cancer Hospital & Institute. For evaluating the antitumor growth ability of Defactinib, the indicated ESCC cells (1 × 106/100 μl PBS/mouse) were subcutaneously inoculated into the right flank of each mouse (n = 5/group). When tumors reached approximately 100 mm3, animals were treated with defactinib (25 mg/kg/day, p.o.) for 3 weeks. The selected dosage and administration of defactinib were referred to previous report.17 For evaluation of FAK activity in tumor tissues, the human phospho-FAK (Tyr397) kit was used. The exact protocol was according to the manufacturer's instruction. Briefly, tumor lysates were incubated in wells of enzyme-linked immunosorbent assay plate for 2 h at 37°C. Then, lysates were discarded and detection antibody solutions were added into the appropriated well to measure the expression of phosphorylated FAK (Tyr397).[2]

The antilymphatic metastasis effect of Defactinib on ESCC cells was examined using a popliteal lymph node metastasis model, which was established in mice by injecting the foot pads with the indicated ESCC cells (1 × 106/100 μl PBS/mouse, n = 5/group). Tumor and lymph node volumes were measured and calculated using the formula: length × width2 × 0.5.[2]

The effect of Defactinib on ESCC metastasis was evaluated using a lung colonization model. Animals were intravenously injected with indicated ESCC cells (1 × 105/100 μl PBS/mouse, n = 5/group) and treated with defactinib. 4 weeks after injection, the mice were killed and the lungs were harvested for hematoxylin and eosin (H&E) staining.[2]

For survival assay, treatments were consistent with above subcutaneous xenografted model. Survival event was recorded when tumor burden reached more than 1 cm3 in diameter or per absolute survival events. For immunohistochemical (IHC) staining evaluation of Ki-67 and CD31 expressions in tumor tissues, tumors were fixed in 10% neutral-buffered formalin for 24 h. Then, tumors were paraffin-embedded and 5 μm sections were cut. Ki-67 and CD31 antibodies (diluted at 1:500) were used for IHC staining.[2]

For evaluation of toxicity of Defactinibon mice, organ tissues, including liver, heart, spleen, and kidney of mice in subcutaneous xenografted model, were collected for H&E staining.[2]

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Dissolved in PBS; 50 mg/kg; Administered through p.o.

Mice bearing SKOV3ip1, SKOV3-TR, HeyA8 or HeyA8-MDR tumors

Pharmacokinetics [https://pubmed.ncbi.nlm.nih.gov/27025608/]
VS-6063/Defactinib is rapidly absorbed, with a median time to peak concentration (Tmax) of 2.0 hours (range 0.5–4.0 hours) after oral administration of 200–600 mg BID. Increased plasma VS-6063 exposure (Cmax and AUC) was not due to dose-proportional increases, and the mean AUC0–12 and AUC0–24 values remained relatively stable across the entire dose range assessed (Figure 1). Doses exceeding 400 mg BID did not result in a significant increase in VS-6063 exposure. On days 1 and 15, the Cmax values were similar in the 400 mg and 600 mg twice-daily dosing groups, and the mean AUC values were relatively consistent across the 200–600 mg twice-daily dosing dose range. On days 1 and 15, clearance appeared to increase with dose, consistent with the fact that the increase in exposure was less than the dose-proportional increase. The median half-life was 2.3 to 4.3 hours for all dosing regimens and on both pharmacokinetic study days. On day 1, the mean CL/F values for the 200 mg, 400 mg, and 600 mg dose groups were 45.6, 105, and 204 L/h, respectively. On day 15, the mean CL/F values for the 200 mg, 400 mg, and 600 mg dose groups were 32.1, 70, and 123 L/h, respectively (Table 3). VS-6063 was detected in the urine of all patients, consistently across all dose groups. The mean renal clearance (CLr) ranged from 0.0855 to 0.179 L/h, representing 0.0439% to 0.356% of the total dose. Systemic concentrations of the four evaluated VS-6063/Defactinib metabolites (M2, M3, M4, and M5) were detected in all nine subjects. On both pharmacokinetic sampling days, the median time to peak plasma concentration (Tmax) for all metabolites across all dose groups ranged from 2.0 to 4.0 hours post-dose. Based on peak plasma concentration (Cmax) and AUC0-12 values relative to VS-6063, M2 was the most abundant metabolite, followed by M4, M3, and finally M5. Exposures to M2 and M4 were both more than 10% higher than that to the parent compound, while exposures to M3 and M5 were less than 10% higher. In urine, the M2 metabolite was the most abundant and was excreted at a higher rate than the parent compound.

Safety and Tolerability [https://pubmed.ncbi.nlm.nih.gov/27025608/]
Table 2 summarizes treatment-related adverse events (AEs) that occurred in at least two subjects. The most common AEs were unconjugated hyperbilirubinemia (7 cases, 78%), fatigue (6 cases, 67%), decreased appetite (4 cases, 44%), and diarrhea (3 cases, 33%). Only one patient in the 200 mg dose group experienced grade 3 unconjugated hyperbilirubinemia. All other toxicities were manageable and predominantly mild (grade 1 or 2). No AEs resulting in death or serious adverse events (SAEs) or premature withdrawal from the study occurred. No dose-limiting toxicities (DLTs) were reported in any dose group. Hyperbilirubinemia is usually asymptomatic and typically develops within the first two weeks of treatment. Patients with grade 1 or 2 unconjugated hyperbilirubinemia can continue treatment, but bilirubin levels may fluctuate significantly during treatment. Hyperbilirubinemia was reported in all dose groups: 3 cases (100%) in the 200 mg dose group, 2 cases (67%) in the 400 mg dose group, and 2 cases (67%) in the 600 mg dose group. One case of grade 3 hyperbilirubinemia occurred in the 200 mg dose group. This patient developed grade 1-2 hyperbilirubinemia on day 7; grade 3 hyperbilirubinemia occurred on day 42 and resolved 6 days after discontinuation of the study drug. All reports of hyperbilirubinemia were considered to be related to Defactinib. No subjects experienced ALT or AST levels exceeding the upper limit of normal. The most common gastrointestinal adverse events were diarrhea (3 cases, 33%) and nausea (2 cases, 22%). One subject (33%) in the 400 mg dose group and two subjects (67%) in the 600 mg dose group reported diarrhea. One patient (33%) in the 200 mg dose group and one patient (33%) in the 600 mg dose group reported nausea. Both cases of nausea were mild. Two of the three cases of diarrhea were also mild. One patient in the 600 mg dose group experienced moderate diarrhea. No clinically significant changes in ECG parameters were observed in any dose group, and the QTc interval was not ≥500 ms in any subject, with no increase in QTc interval from baseline exceeding 30 ms.

[1]. Role of focal adhesion kinase in regulating YB-1-mediated resistance in ovarian cancer. J Natl Cancer Inst. 2013 Oct 2;105(19):1485-95.

[2]. Focal adhesion kinase (FAK) inhibitor-defactinib suppresses the malignant progression of human esophageal squamous cell carcinoma (ESCC) cells via effective blockade of PI3K/AKT axis and downstream molecular network. Mol Carcinog. 2021 Feb;60(2):113-124.

Defactinib has been investigated for the treatment of malignant pleural mesothelioma. Defactinib is a small molecule focal adhesion kinase (FAK) inhibitor with high oral bioavailability and potential anti-angiogenic and antitumor activity. Defactinib inhibits FAK, potentially preventing the activation of multiple integrin-mediated downstream signaling pathways, including the RAS/MEK/ERK and PI3K/Akt pathways, thereby inhibiting tumor cell migration, proliferation, survival, and tumor angiogenesis. Tyrosine kinase FAK is an integrin signaling molecule that is normally activated by binding to integrins in the extracellular matrix (ECM), but may be upregulated and constitutively activated in various tumor cell types. See also: Defactinib hydrochloride (note moved to). Background: We previously found that focal adhesion kinase (FAK) inhibition enhances the sensitivity of ovarian cancer to taxanes; however, the mechanism is not fully understood.
Methods
We characterized the biological responses of taxane-resistant and taxane-sensitive ovarian cancer models using a novel FAK inhibitor (VS-6063). We used reverse-phase protein microarray (RPPA) technology to identify novel downstream targets in taxane-resistant cell lines. Furthermore, we analyzed the correlation between nuclear and cytoplasmic expression of FAK and YB-1 and clinicopathological data in 105 ovarian cancer samples. All statistical tests were two-tailed, and p-values were calculated using Student's t-test or Fisher's exact test.
Results
We found that VS-6063 inhibited FAK phosphorylation at Tyr397 in a time- and dose-dependent manner. Combination therapy of VS-6063 with paclitaxel significantly reduced cell proliferation and promoted apoptosis, resulting in a 92.7% to 97.9% reduction in tumor weight. RPPA data showed that VS-6063 reduced AKT and YB-1 levels in taxane-resistant cell lines. FAK inhibition enhances the chemosensitivity of taxane-resistant cells by reducing YB-1 phosphorylation levels and subsequently reducing CD44 expression in an AKT-dependent manner. In human ovarian cancer samples, nuclear FAK expression was associated with increased nuclear YB-1 expression (χ² = 37.7; P < .001). Co-expression of nuclear FAK and YB-1 was associated with significantly shortened median overall survival (24.9 months vs 67.3 months; hazard ratio = 2.64; 95% confidence interval = 1.38 to 5.05; P = .006). Conclusion We have discovered a new pathway by which VS-6063 overcomes YB-1-mediated paclitaxel resistance by inhibiting FAK in an AKT-dependent manner. These findings are of great significance for clinical trials that target FAK. [1] Due to the lack of targeted drugs, the clinical treatment of esophageal squamous cell carcinoma (ESCC) is not ideal. Follicular adhesion kinase (FAK) is a non-receptor tyrosine kinase involved in various tumorigenesis processes, and recent studies have shown it to be a promising target for ESCC treatment. This study found that the specific FAK inhibitor defactinib effectively inhibited the malignant proliferation of ESCC cells. Mechanistically, defactinib induces the dissociation of phosphatidylinositol-3-kinase (PI3K) from FAK in a dose- and time-dependent manner, thereby blocking the protein kinase B (AKT) signaling pathway and inhibiting the expression of multiple oncogenes, such as SOX2, MYC, EGFR, MET, MDM2, and TGFBR2. The expression of these oncogenes has been confirmed by microarray and real-time polymerase chain reaction (RT-PCR). Specifically, in vitro experiments showed that the inhibition of the FAK-mediated PI3K/AKT signaling pathway and its downstream ESCC-specific biomarkers can last for 24 hours, thus ensuring the durability and efficacy of treatment. Importantly, defactinib inhibited tumor growth and metastasis and improved overall survival in xenograft animals without producing significant systemic toxicity. Our data suggest that FAK inhibition can provide an excellent targeted therapy for ESCC by effectively inhibiting the PI3K/AKT pathway and its downstream molecular networks. [2]

C20H21F3N8O3S

510.492751836777

510.14

C, 47.06; H, 4.15; F, 11.16; N, 21.95; O, 9.40; S, 6.28

1073154-85-4

Defactinib hydrochloride;1073160-26-5; 1073154-85-4; 1345713-71-4

25117126

White to off-white solid powder

1.5±0.1 g/cm3

1.616

-0.74

3

13

8

35

804

0

S(C)(N(C)C1C(CNC2C(C(F)(F)F)=CN=C(NC3C=CC(C(NC)=O)=CC=3)N=2)=NC=CN=1)(=O)=O

FWLMVFUGMHIOAA-UHFFFAOYSA-N

InChI=1S/C20H21F3N8O3S/c1-24-18(32)12-4-6-13(7-5-12)29-19-28-10-14(20(21,22)23)16(30-19)27-11-15-17(26-9-8-25-15)31(2)35(3,33)34/h4-10H,11H2,1-3H3,(H,24,32)(H2,27,28,29,30)

N-methyl-4-((4-(((3-(N-methylmethylsulfonamido)pyrazin-2-yl)methyl)amino)-5-(trifluoromethyl)pyrimidin-2-yl)amino)benzamide

VS-6063; PF-04554878; Defactinib; 1073154-85-4; PF-04554,878; VS-6,063; 1345713-71-4; N-methyl-4-((4-(((3-(N-methylmethylsulfonamido)pyrazin-2-yl)methyl)amino)-5-(trifluoromethyl)pyrimidin-2-yl)amino)benzamide; N-methyl-4-[[4-[[3-[methyl(methylsulfonyl)amino]pyrazin-2-yl]methylamino]-5-(trifluoromethyl)pyrimidin-2-yl]amino]benzamide; Defactinib (VS-6063, PF-04554878); VS6063; VS 6063; PF04554878; PF 04554878; PF4554878;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: 2.5 mg/mL (4.90 mM) in 5% DMSO + 40% PEG300 + 5% Tween80 + 50% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (4.07 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (4.07 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 5% DMSO+50% PEG 300+5% Tween 80+ddH2O: 5mg/mL

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 (Please use freshly prepared in vivo formulations for optimal results.)