Selective Fibroblast Growth Factor Receptor Inhibitors Research Articles

PD173074, a selective FGFR inhibitor, reverses ABCB1-mediated drug resistance in cancer cells

Specific tyrosine kinase inhibitors were recently reported to modulate the activity of ABC transporters, leading to an increase in the intracellular concentration of their substrate drugs. In this study, we determine whether PD173074, a specific fibroblast growth factor receptor (FGFR) inhibitor, could reverse ABC transporter-mediated multidrug resistance. 3-(4,5-Dimethylthiazol-yl)-2,5-diphenyllapatinibrazolium bromide assay was used to determine the effect of PD173074 on reversal of ABC transporter-mediated multidrug resistance (MDR). In addition, [³H]-paclitaxel accumulation/efflux assay, western blotting analysis, ATPase, and photoaffinity labeling assays were done to study the interaction of PD173074 on ABC transporters. PD173074 significantly sensitized both ABCB1-transfected and drug-selected cell lines overexpressing this transporter to substrate anticancer drugs colchicine, paclitaxel, and vincristine. This effect of PD173074 is specific to ABCB1, as no significant interaction was detected with other ABC transporters such as ABCC1 and ABCG2. The observed reversal effect seems to be primarily due to the decreased active efflux of [³H]-paclitaxel in ABCB1 overexpressing cells observed in efflux assay. In addition, no significant change in the ABCB1 expression was observed when ABCB1 overexpressing cells were exposed to 5 μM PD173074 for up to 3 days, thereby further suggesting its role in modulating the function of the transporter. In addition, PD173074 stimulated the ATPase activity of ABCB1 in a concentration-dependent manner, indicating a direct interaction with the transporter. Interestingly, PD173074 did not inhibit photolabeling of ABCB1 with [¹²⁵I]-iodoarylazidoprazosin (IAAP), showing that it binds at a site different from that of IAAP in the drug-binding pocket. Here, we report for the first time, PD173074, an inhibitor of the FGFR, to selectively reverse ABCB1 transporter-mediated MDR by directly blocking the efflux function of the transporter.

FGFR2 Gene Amplification in Gastric Cancer Predicts Sensitivity to the Selective FGFR Inhibitor AZD4547

FGFR gene aberrations are associated with tumor growth and survival. We explored the role of FGFR2 amplification in gastric cancer and the therapeutic potential of AZD4547, a potent and selective ATP-competitive receptor tyrosine kinase inhibitor of fibroblast growth factor receptor (FGFR)1-3, in patients with FGFR2-amplified gastric cancer. Array-comparative genomic hybridization and FISH were used to identify FGFR2 amplification in gastric cancer patient tumor samples. The effects of FGFR2 modulation were investigated in gastric cancer cells with FGFR2 amplification and in patient-derived gastric cancer xenograft (PDGCX) models using two approaches: inhibition with AZD4547 and short hairpin RNA (shRNA) knockdown of FGFR2. Amplification of the FGFR2 gene was identified in a subset of Chinese and Caucasian patients with gastric cancer. Gastric cancer cell lines SNU-16 and KATOIII, carrying the amplified FGFR2 gene, were extremely sensitive to AZD4547 in vitro with GI50 values of 3 and 5 nmol/L, respectively. AZD4547 effectively inhibited phosphorylation of FGFR2 and its downstream signaling molecules and induced apoptosis in SNU-16 cells. Furthermore, inhibition of FGFR2 signaling by AZD4547 resulted in significant dose-dependent tumor growth inhibition in FGFR2-amplified xenograft (SNU-16) and PDGCX models (SGC083) but not in nonamplified models. shRNA knockdown of FGFR2 similarly inhibited tumor growth in vitro and in vivo. Finally, compared with monotherapy, we showed enhancement of in vivo antitumor efficacy using AZD4547 in combination with chemotherapeutic agents. FGFR2 pathway activation is required for driving growth and survival of gastric cancer carrying FGFR2 gene amplification both in vitro and in vivo. Our data support therapeutic intervention with FGFR inhibitors, such as AZD4547, in patients with gastric cancer carrying FGFR2 gene amplification.

Abstract 980: PD173074, a selective FGFR inhibitor, reverses ABCB1-mediated drug resistance in cancer cells.

Abstract Multidrug resistance (MDR) through overexpression of ATP-binding cassette (ABC) transporters has long evaded chemotherapy in cancer patients. Specific tyrosine kinase inhibitors (TKIs) were recently reported to modulate these ABC transporters, leading to an increase in the intracellular concentration of their substrate drugs. Here, we report for the first time, PD173074 an inhibitor of the fibroblast growth factor receptor (FGFR), to selectively inhibit ABC subfamily B member 1 (ABCB1/P-glycoprotein) transporter. PD173074 significantly sensitized both ABCB1 transfected and drug selected cell lines overexpressing this transporter to anticancer drugs colchicine, paclitaxel, and vincristine. This effect of PD173074 is specific, as no significant interaction was detected with other ABC transporters such as ABCC1, and ABCG2. The observed inhibition was primarily due to the decreased active efflux of [3H]-paclitaxel in ABCB1 overexpressing cells. However, no significant change in the ABCB1 expression was observed when ABCB1 overexpressing cells were exposed to 5 μM PD173074 for up to 3 days thereby suggesting its role in modulating the function of the transporter. In addition, PD173074 stimulated the ATPase activity of ABCB1 in a concentration-dependent manner, indicating a direct interaction with the transporter. Interestingly, PD173074 did not inhibit the photolabeling of ABCB1 with [125I]-Iodoarylazidoprazosin (IAAP) showing that it binds at a site different from that of IAAP in the drug-binding pocket. In conclusion, PD173074 could selectively reverse ABCB1-mediated MDR by directly blocking the efflux function of ABCB1. Citation Format: Atish S. Patel, Amit Tiwari, Eduardo Chufan, Satyakam Singh, Kamlesh Sodani, Nagaraju Anreddy, Tanaji Talele, Suresh Ambudkar, Ralph Stephani, Zhe-Sheng Chen. PD173074, a selective FGFR inhibitor, reverses ABCB1-mediated drug resistance in cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 980. doi:10.1158/1538-7445.AM2013-980

Abstract LB-145: Results of a phase I study of AZD4547, an inhibitor of fibroblast growth factor receptor (FGFR), in patients with advanced solid tumors .

Abstract Background: AZD4547 is an orally bioavailable, selective inhibitor of FGFR 1, 2, and 3, with activity in a wide range of cell lines and xenografts dependent upon FGFR signalling, including patient-derived explant models with FGFR gene amplification. Methods: A 3-part study of AZD4547 was initiated in patients with advanced solid tumors (NCT00979134): Part A to determine the maximum tolerated dose (MTD) and/or continuous tolerable dose (RD); Part B to characterize the pharmacokinetic and safety profile (Parts A and B unselected for FGFR amplification); Part C1 to assess safety and clinical activity of AZD4547 (80 mg bid continuous dosing) in patients with advanced solid tumors prospectively selected for amplification of FGFR 1 and 2. FGFR gene amplification status was determined using fluorescent in situ hybridization (FISH) analysis of archival or fresh tumor tissue. Pharmacodynamic biomarkers including phosphate and FGF23 were assessed in plasma samples. Results: At data cut-off (15 January 2013), 43 patients had been treated (dose range 20-200 mg bid) in the dose-escalation phase (Part A) of this study, and the RD was determined as 80 mg bid continuous dosing. Dose-limiting toxicities included increased liver enzymes, stomatitis, renal failure, hyperphosphataemia, and mucositis. In the dose-expansion phase of the study (Part B), a total of 6 patients were treated to confirm the tolerability of the RD. In Part C1, 21 patients with FGFR 1 or 2 amplified tumors received AZD4547 80 mg bid; these patients had diverse tumor types and a range of gene copy number gain (mostly low gene copy number <6). One squamous NSCLC patient in the C1 arm, with high copy number FGFR 1 amplification and who had received 2 previous lines of anti-cancer therapy, experienced a partial response lasting 12 weeks (patient discontinued study treatment due to RECIST disease progression at 24 weeks). An additional 4 patients in Part C1 had long periods of disease stabilization (≥24 weeks; advanced breast cancer [n=1], squamous NSCLC [n=1] and transitional cell carcinoma [n=2]). Pharmacokinetic data were generally both predictable and linear. The most common adverse events (AEs) reported were hyperphosphataemia, dry skin and mucous membranes, and retinal pigmented epithelial detachment (RPED). AEs were generally mild to moderate and reversible. Parts C2 (squamous NSCLC) and C3 (gastric cancer) are ongoing. Conclusions: AZD4547 80 mg bid continuous dosing was generally tolerated. Encouraging evidence of anti-tumor activity was seen in some patients, most notably a partial response in a patient with squamous NSCLC who had a high level FGFR gene amplification. Pharmacodynamic plasma biomarker data will be presented. Studies remain ongoing in patients with tumors selected for high levels of FGFR amplification. Citation Format: Fabrice Andre, Malcolm Ranson, Emma Dean, Andrea Varga, Ruud van der Noll, Paul K. Stockman, Dana Ghiorghiu, Elaine Kilgour, Paul D. Smith, Merran Macpherson, Peter Lawrence, Andrew Hastie, Jan HM Schellens. Results of a phase I study of AZD4547, an inhibitor of fibroblast growth factor receptor (FGFR), in patients with advanced solid tumors . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-145. doi:10.1158/1538-7445.AM2013-LB-145

AZD4547: An Orally Bioavailable, Potent, and Selective Inhibitor of the Fibroblast Growth Factor Receptor Tyrosine Kinase Family

The fibroblast growth factor (FGF) signaling axis is increasingly implicated in tumorigenesis and chemoresistance. Several small-molecule FGF receptor (FGFR) kinase inhibitors are currently in clinical development; however, the predominant activity of the most advanced of these agents is against the kinase insert domain receptor (KDR), which compromises the FGFR selectivity. Here, we report the pharmacologic profile of AZD4547, a novel and selective inhibitor of the FGFR1, 2, and 3 tyrosine kinases. AZD4547 inhibited recombinant FGFR kinase activity in vitro and suppressed FGFR signaling and growth in tumor cell lines with deregulated FGFR expression. In a representative FGFR-driven human tumor xenograft model, oral administration of AZD4547 was well tolerated and resulted in potent dose-dependent antitumor activity, consistent with plasma exposure and pharmacodynamic modulation of tumor FGFR. Importantly, at efficacious doses, no evidence of anti-KDR-related effects were observed, confirming the in vivo FGFR selectivity of AZD4547. Taken together, our findings show that AZD4547 is a novel selective small-molecule inhibitor of FGFR with potent antitumor activity against FGFR-deregulated tumors in preclinical models. AZD4547 is under clinical investigation for the treatment of FGFR-dependent tumors.

Abstract C193: FGFR genetic alterations predict for sensitivity to NVP-BGJ398, a novel orally bioavailable, selective, and potent FGFR inhibitor.

Abstract The fibroblast growth factor receptor (FGFR) family of receptor tyrosine kinases (RTK) consists of FGFR1, FGFR2, FGFR3 and FGFR4, which are the high affinity receptors for 22 different FGF ligands. These ligand-receptor combinations elicit a broad spectrum of biological activities during development and in adult tissue homeostasis. In contrast, de-regulated FGF signaling has been linked to diseases, most prominently in the pathogenesis of multiple cancers. Epidemiological and molecular studies have revealed a variety of genetic alterations in components of the FGF/FGFR signaling system which result in aberrant receptor activation and thus, enhanced downstream signaling. Hence, on this basis, targeted inhibition of FGFRs can be exploited for therapeutic intervention. In this report we disclose NVP-BGJ398, a novel orally bioavailable, selective and potent kinase inhibitor of the FGFRs currently in Phase I clinical trials. We further describe the identification of patient stratification biomarkers for NVP-BGJ398 by intersecting genome-wide gene expression data with genomic alterations and cell line sensitivity data across an annotated collection of cancer cell lines termed “Cancer Cell Line Encyclopedia”. We show that genetic alterations for selected FGF/FGFR family members predict for sensitivity to NVP-BGJ398 in specific cancer types, thus providing the rationale for clinical trials in well defined subpopulations of cancer patients based upon the presence of these molecular abnormalities. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C193.

FGFR Signaling Promotes the Growth of Triple-Negative and Basal-Like Breast Cancer Cell Lines Both In Vitro and In Vivo

The oncogenic drivers of triple-negative (TN) and basal-like breast cancers are largely unknown. Substantial evidence now links aberrant signaling by the fibroblast growth factor receptors (FGFR) to the development of multiple cancer types. Here, we examined the role of FGFR signaling in TN breast cancer. We examined the sensitivity of a panel of 31 breast cancer cell lines to the selective FGFR inhibitor PD173074 and investigated the potential mechanisms underlying sensitivity. TN breast cancer cell lines were more sensitive to PD173074 than comparator cell lines (P = 0.011), with 47% (7/15) of TN cell lines showing significantly reduced growth. The majority of TN cell lines showed only modest sensitivity to FGFR inhibition in two-dimensional growth but were highly sensitive in anchorage-independent conditions. PD173074 inhibited downstream mitogen-activated protein kinase and PI3K-AKT signaling and induced cell-cycle arrest and apoptosis. Basal-like breast cancer cell lines were found to express FGF2 ligand (11/21 positive) and, similarly, 62% of basal-like breast cancers expressed FGF2, as assessed by immunohistochemistry compared with 5% of nonbasal breast cancers (P < 0.0001). RNA interference targeting of FGF2 in basal-like cell lines significantly reduced growth in vitro and reduced down stream signaling, suggesting an autocrine FGF2 signaling loop. Treatment with PD173074 significantly reduced the growth of CAL51 basal-like breast cancer cell line xenografts in vivo. Basal-like breast cancer cell lines, and breast cancers, express autocrine FGF2 and show sensitivity to FGFR inhibitors, identifying a potential novel therapeutic approach for these cancers.