Changes of the lower limb deformity in children with FGF23-related hypophosphatemic rickets treated with Burosumab: a single-center prospective study

Fibroblast growth factor 23 (FGF23)-related hypophosphatemic rickets (HPR) are characterized by excess circulating FGF23 and low concentrations of serum phosphorus, leading to skeletal manifestations of rickets, including lower limb deformities in children. The objective of this study was to prospectively evaluate whether treatment with burosumab, a monoclonal antibody neutralizing FGF23, changes lower limb deformities in HPR. Patients who were 15 years of age or younger with a documented clinical diagnosis of HPR, receiving burosumab treatment, and had a minimum follow-up period of one year were included in the study. Various radiological parameters were measured from anteroposterior and lateral radiographs of the bilateral lower limbs taken before administration of burosumab and at 3, 6, 9, and 12 months after treatment for evaluation of lower limb alignment. Outcome was classified as 'improvement', 'no change', or 'deterioration' after 12 months treatment. Five patients (10 limbs), with a mean age of 7.2 years were included in this study. The outcome was 'improvement' in six limbs and 'no change' in four limbs. There were no limbs of 'deterioration'. The improvement in deformities after treatment was more significant in younger patients who originally showed severe lower limb deformities. Older patients with milder deformities, on the other hand, showed less improvement. Burosumab therapy favorably changed lower-limb malalignment in children with FGF23-related HPR.

Synthetic and Naturally Occurring Heterocyclic Anticancer Compounds with Multiple Biological Targets

Cancer is a complex group of diseases initiated by abnormal cell division with the potential of spreading to other parts of the body. The advancement in the discoveries of omics and bio- and cheminformatics has led to the identification of drugs inhibiting putative targets including vascular endothelial growth factor (VEGF) family receptors, fibroblast growth factors (FGF), platelet derived growth factors (PDGF), epidermal growth factor (EGF), thymidine phosphorylase (TP), and neuropeptide Y4 (NY4), amongst others. Drug resistance, systemic toxicity, and drug ineffectiveness for various cancer chemo-treatments are widespread. Due to this, efficient therapeutic agents targeting two or more of the putative targets in different cancer cells are proposed as cutting edge treatments. Heterocyclic compounds, both synthetic and natural products, have, however, contributed immensely to chemotherapeutics for treatments of various diseases, but little is known about such compounds and their multimodal anticancer properties. A compendium of heterocyclic synthetic and natural product multitarget anticancer compounds, their IC50, and biological targets of inhibition are therefore presented in this review.

Fibroblast Growth Factor Inhibitors for Treating Locally Advanced/Metastatic Bladder Urothelial Carcinomas via Dual Targeting of Tumor-Specific Oncogenic Signaling and the Tumor Immune Microenvironment

Locally advanced or metastatic urothelial bladder cancer (a/m UBC) is currently treated using platinum-based combination chemotherapy. Immune checkpoint inhibitors (ICIs) are the preferred second-line treatment options for cisplatin-eligible a/m UBC patients and as first-line options in cisplatin-ineligible settings. However, the response rates for ICI monotherapy are modest (~20%), which necessitates the exploration of alternative strategies. Dysregulated activation of fibroblast growth factor receptor (FGFR) signaling enhances tumor proliferation, survival, invasion, angiogenesis, and immune evasion. The recent U.S. Food and Drug Administration approval of erdafitinib and the emergence of other potent and selective FGFR inhibitors (FGFRis) have shifted the treatment paradigm for patients with a/m UBC harboring actionable FGFR2 or FGFR3 genomic alterations, who often have a minimal-to-modest response to ICIs. FGFRi-ICI combinations are therefore worth exploring, and their preliminary response rates and safety profiles are promising. In the present review, we summarize the impact of altered FGFR signaling on a/m UBC tumor evolution, the clinical development of FGFRis, the rationale for FGFRi-ICI combinations, current trials, and prospective research directions.

Chemical modification of NSC12 leads to a specific FGF-trap with antitumor activity in multiple myeloma

Inhibition of FGF/FGFR signaling is a promising strategy for the treatment of malignances dependent from FGF stimulation, including multiple myeloma (MM). The steroidal derivative NSC12 (compound 1) is a pan-FGF trap endowed with antitumor activity in vivo. Chemical modifications of compound 1 were explored to investigate structure-activity relationships, focusing on the role of the bis(trifluoromethyl)1,3-propanediol chain, the stereochemistry at C20 and functionalization of C3 position. Our studies unveiled compound 25b, the pregnane 3-keto 20R derivative of compound 1 as an effective agent, blocking the proliferation of MM cells in vitro by inhibiting FGF-dependent receptor activation and slowing MM growth in vivo. Importantly, the absence of the hydroxyl group at C3 prevents binding to estrogen receptors, which might concur to the antitumor activity observed for compound 1, leading to a specific FGF/FGFR system inhibitor, and further supporting the role of FGFR in anticancer therapy in MM.

Expression Atlas of FGF and FGFR Genes in Pancancer Uncovered Predictive Biomarkers for Clinical Trials of Selective FGFR Inhibitors

BACKGROUND

Clinical trials based on FGFR mutation or amplification as a druggable target of FGFR inhibitors have produced disappointing clinical outcomes. Therefore, the identification of predictive biomarkers for FGFR-targeted agents has remained a crucial issue.

METHODS

Expression profiles of FGFs and FGFRs in 8,111 patients with 24 types of solid tumors and 879 tumor cell lines along with drug sensitivity data were obtained and followed by integrative bioinformatics analysis.

RESULTS

FGFs and FGFRs were frequently dysregulated in pancancer. Most of the expression of FGFs and FGFRs were significantly associated with overall survival in at least two cancer types. Moreover, tumor cell lines with high FGFR1/3 expression were more sensitive to FGFR inhibitor PD173074, especially in breast, liver, lung and ovarian cancer. The predicted positive ratios of FGFR1-4 were generally over 10% in most tumor types, especially in squamous cell carcinoma. High positive FGFR1 or 3 expression ratios were predicted in cholangiocarcinoma (58%), followed by bladder cancer (42%), endometrial carcinoma (35%), and ovarian cancer (34%).

CONCLUSIONS

FGFR expression was a promising predictive biomarker for FGFR inhibition response in clinical trials, and different combinations of FGFR genes should be used in screening for patients in certain tumor types.

Clinical Potential of Targeting Fibroblast Growth Factor-23 and αKlotho in the Treatment of Uremic Cardiomyopathy

Chronic kidney disease is highly prevalent, affecting 10% to 15% of the adult population worldwide and is associated with increased cardiovascular morbidity and mortality. As chronic kidney disease worsens, a unique cardiovascular phenotype develops characterized by heart muscle disease, increased arterial stiffness, atherosclerosis, and hypertension. Cardiovascular risk is multifaceted, but most cardiovascular deaths in patients with advanced chronic kidney disease are caused by heart failure and sudden cardiac death. While the exact drivers of these deaths are unknown, they are believed to be caused by uremic cardiomyopathy: a specific pattern of myocardial hypertrophy, fibrosis, with both diastolic and systolic dysfunction. Although the pathogenesis of uremic cardiomyopathy is likely to be multifactorial, accumulating evidence suggests increased production of fibroblast growth factor-23 and αKlotho deficiency as potential major drivers of cardiac remodeling in patients with uremic cardiomyopathy. In this article we review the increasing understanding of the physiology and clinical aspects of uremic cardiomyopathy and the rapidly increasing knowledge of the biology of both fibroblast growth factor-23 and αKlotho. Finally, we discuss how dissection of these pathological processes is aiding the development of therapeutic options, including small molecules and antibodies, directly aimed at improving the cardiovascular outcomes of patients with chronic kidney disease and end-stage renal disease.

Diagnosis, treatment-monitoring and follow-up of children and adolescents with X-linked hypophosphatemia (XLH)

Early diagnosis, optimal therapeutic management and regular follow up of children with X-linked hypophosphatemia (XLH) determine their long term outcomes and future quality of life. Biochemical screening of potentially affected newborns in familial cases and improving physician's knowledge on clinical signs, symptoms and biochemical characteristics of XLH for de novo cases should lead to earlier diagnosis and treatment initiation. The follow-up of children with XLH includes clinical, biochemical and radiological monitoring of treatment (efficacy and complications) and screening for XLH-related dental, neurosurgical, rheumatological, cardiovascular, renal and ENT complications. In 2018, the European Union approved the use of burosumab, a humanized monoclonal anti-FGF23 antibody, as an alternative therapy to conventional therapy (active vitamin D analogues and phosphate supplements) in growing children with XLH and insufficiently controlled disease. Diagnostic criteria of XLH and the principles of disease management with conventional treatment or with burosumab are reviewed in this paper.

Management of X-linked hypophosphatemia in adults

X-linked hypophosphatemia (XLH) is caused by mutations in the PHEX gene which result in Fibroblast Growth Factor-23 (FG-F23) excess and phosphate wasting. Clinically, XLH children present with rickets, bone deformities and short stature. In adulthood, patients may still be symptomatic with bone and joint pain, osteomalacia-related fractures or pseudofractures, precocious osteoarthrosis, enthesopathy, muscle weakness and severe dental anomalies. Besides these musculoskeletal and dental manifestations, adult XLH patients are also prone to secondary and tertiary hyperparathyroidism, cardiovascular and metabolic disorders. Pathophysiology of hyperparathyroidism is only partially understood but FGF23 excess and deficient production of calcitriol likely contributes to its development. Similarly, the pathophysiological mechanisms of potential cardiovascular and metabolic involvements are not clear, but FGF-23 excess may play an essential role. Treatment should be considered in symptomatic patients, patients undergoing orthopedic or dental surgery and women during pregnancy and lactation. Treatment with oral phosphate salts and active vitamin D analogs has incomplete efficacy and potential risks. Burosumab, a recombinant human monoclonal antibody against FGF-23, has proven its efficacy in phase 2 and phase 3 clinical trials in adult patients with XLH, but currently its position as first line or second line treatment differ among the countries.

Generation and validation of novel conditional flox and inducible Cre alleles targeting fibroblast growth factor 18 (Fgf18)

BACKGROUND

Fibroblast growth factor 18 (FGF18) functions in the development of several tissues, including the lung, limb bud, palate, skeleton, central nervous system, and hair follicle. Mice containing a germline knockout of Fgf18 (Fgf18 -/- ) die shortly after birth. Postnatally, FGF18 is being evaluated for pathogenic roles in fibrosis and several types of cancer. The specific cell types that express FGF18 have been difficult to identify, and the function of FGF18 in postnatal development and tissue homeostasis has been hampered by the perinatal lethality of Fgf18 null mice.

RESULTS

We engineered a floxed allele of Fgf18 (Fgf18 flox ) that allows conditional gene inactivation and a CreERT2 knockin allele (Fgf18 CreERT2 ) that allows the precise identification of cells that express Fgf18 and their lineage. We validated the Fgf18 flox allele by targeting it in mesenchymal tissue and primary mesoderm during embryonic development, resulting in similar phenotypes to those observed in Fgf18 null mice. We also use the Fgf18 CreERT2 allele, in combination with a conditional fluorescent reporter to confirm known and identify new sites of Fgf18 expression.

CONCLUSION

These alleles will be useful to investigate FGF18 function during organogenesis and tissue homeostasis, and to target specific cell lineages at embryonic and postnatal time points.

FGF19-FGFR4 Signaling in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common type of cancer, with an increasing mortality rate. Aberrant expression of fibroblast growth factor 19-fibroblast growth factor receptor 4 (FGF19-FGFR4) is reported to be an oncogenic-driver pathway for HCC patients. Thus, the FGF19-FGFR4 signaling pathway is a promising target for the treatment of HCC. Several pan-FGFR (1-4) and FGFR4-specific inhibitors are in different phases of clinical trials. In this review, we summarize the information, recent developments, binding modes, selectivity, and clinical trial phases of different available FGFR4/pan-FGF inhibitors. We also discuss future perspectives and highlight the points that should be addressed to improve the efficacy of these inhibitors.

Efficacy and safety of burosumab in children aged 1-4 years with X-linked hypophosphataemia: a multicentre, open-label, phase 2 trial

BACKGROUND

Children with X-linked hypophosphataemia have high concentrations of circulating phosphatonin fibroblast growth factor 23 (FGF23), which causes renal phosphate wasting and hypophosphataemia, rickets, skeletal deformities, and growth impairment. Burosumab, a human monoclonal antibody against FGF23, improves phosphate homoeostasis and rickets in children aged 5-12 years with X-linked hypophosphataemia. We aimed to assess the safety and efficacy of burosumab in younger children with X-linked hypophosphataemia.

METHODS

In this open-label, phase 2 trial at three hospitals in the USA, children (aged 1-4 years) with X-linked hypophosphataemia received burosumab (0·8 mg/kg) via subcutaneous injection every 2 weeks for 64 weeks. The dose was increased to 1·2 mg/kg if two consecutive pre-dose serum phosphorus concentrations were below 1·03 mmol/L (3·2 mg/dL), serum phosphorus had increased by less than 0·16 mmol/L (<0·5 mg/dL) from baseline, and a dose of burosumab had not been missed. Participants could continue to receive burosumab for up to an additional 96 weeks during the extension period. Key inclusion criteria were age 1-4 years at the time of informed consent; fasting serum phosphorus concentration of less than 0·97 mmol/L (3·0 mg/dL); serum creatinine 8·8-35·4 μmol/L (0·1-0·4 mg/dL); radiographic evidence of rickets (at least five participants were required to have a Thacher Rickets Severity Score of ≥1·5 at the knee); and a confirmed PHEX mutation or a variant of unknown significance in the patient or direct relative also affected with X-linked hypophosphataemia. Conventional therapy was stopped upon enrolment. The coprimary endpoints were safety and change from baseline to week 40 in fasting serum phosphorus concentrations. Changes in rickets severity from baseline to weeks 40 and 64 (assessed radiographically using Thacher Rickets Severity Score and an adaptation of the Radiographic Global Impression of Change), and recumbent length or standing height, were key secondary outcomes. This trial is registered with ClinicalTrials.gov, number NCT02750618, and is ongoing.

FINDINGS

Between May 16, 2016, and June 10, 2016, we enrolled 13 children with X-linked hypophosphataemia. All 13 children completed 64 weeks of treatment and were included in the efficacy and safety analysis; none exceeded 70 weeks of treatment at the time of analysis. Serum phosphorus least squares mean increase from baseline to week 40 of treatment was 0·31 mmol/L (SE 0·04; 95% CI 0·24-0·39; 0·96 mg/dL [SE 0·12]; p<0·0001). All patients had at least one adverse event. 14 treatment-related adverse events, mostly injection site reactions, occurred in five children. One serious adverse event considered unrelated to treatment (tooth abscess) occurred in a child with a history of tooth abscess. All other adverse events were mild to moderate, except a severe food allergy considered unrelated to treatment. No instances of nephrocalcinosis or noteworthy changes in the results of a standard safety chemistry panel emerged. Total Thacher Rickets Severity Score decreased by a least squares mean of -1·7 (SE 0·1; p<0·0001) from baseline to week 40 and by -2·0 (SE 0·1; p<0·0001) by week 64. The Radiographic Global Impression of Change score also indicated significant improvement, with a least squares mean score of +2·3 (SE 0·1) at week 40 and +2·2 (0·1) at week 64 (both p<0·0001). Mean length or standing height Z score was maintained from baseline to week 64.

INTERPRETATION

Burosumab had a favourable safety profile, increased serum phosphorus, and improved rickets and prevented early declines in growth in children aged 1-4 years with X-linked hypophosphataemia. These findings could substantially alter the treatment of young children with X-linked hypophosphataemia.

FUNDING

Ultragenyx Pharmaceutical and Kyowa Kirin International.

Outcome of adult patients with X-linked hypophosphatemia caused by PHEX gene mutations

X-linked hypophosphatemia (XLH) is the most common monogenic disorder causing hypophosphatemia. This case-note review documents the clinical features and the complications of treatment in 59 adults (19 male, 40 female) with XLH. XLH is associated with a large number of private mutations; 37 different mutations in the PHEX gene were identified in this cohort, 14 of which have not been previously reported. Orthopaedic involvement requiring surgical intervention (osteotomy) was frequent. Joint replacement and decompressive laminectomy were observed in those older than 40 years. Dental disease (63%), nephrocalcinosis (42%), and hearing impairment (14%) were also common. The rarity of the disease and the large number of variants make it difficult to discern specific genotype-phenotype relationships. A new treatment, an anti-FGF23 antibody, that may affect the natural history of the disease is currently being investigated in clinical trials.

Targeting FXR and FGF19 to Treat Metabolic Diseases-Lessons Learned From Bariatric Surgery

Bariatric surgery procedures, such as Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), are the most effective interventions available for sustained weight loss and improved glucose metabolism. Bariatric surgery alters the enterohepatic bile acid circulation, resulting in increased plasma bile levels as well as altered bile acid composition. While it remains unclear why both VSG and RYGB can alter bile acids, it is possible that these changes are important mediators of the effects of surgery. Moreover, a molecular target of bile acid synthesis, the bile acid-activated transcription factor FXR, is essential for the positive effects of VSG on weight loss and glycemic control. This Perspective examines the relationship and sequence of events between altered bile acid levels and composition, FXR signaling, and gut microbiota after bariatric surgery. We hypothesize that although bile acids and FXR signaling are potent mediators of metabolic function, unidentified downstream targets are the main mediators behind the benefits of weight-loss surgery. One of these targets, the gut-derived peptide FGF15/19, is a potential molecular and therapeutic marker to explain the positive metabolic effects of bariatric surgery. Focusing research efforts on identifying these complex molecular mechanisms will provide new opportunities for therapeutic strategies to treat obesity and metabolic dysfunction.

Inhibition of fibroblast growth factor 23 (FGF23) signaling rescues renal anemia

Severe anemia and iron deficiency are common complications in chronic kidney disease. The cause of renal anemia is multifactorial and includes decreased erythropoietin (Epo) production, iron deficiency, and inflammation, and it is currently treated with injections of synthetic Epo. However, the use of recombinant Epo has several adverse effects. We previously reported that high fibroblast growth factor 23 (FGF23) levels in mice are associated with decreased red blood cell production, whereas genetic inactivation of Fgf23 results in expansion of the erythroid lineage. The present study is the first to show that high FGF23 levels in a mouse model of renal failure contribute to renal anemia, and inhibiting FGF23 signaling stimulates erythropoiesis and abolishes anemia and iron deficiency. Moreover, we show that inhibition of FGF23 signaling significantly decreases erythroid cell apoptosis and influences the commitment of hematopoietic stem cells toward the erythroid linage. Furthermore, we show that blocking FGF23 signaling attenuates inflammation, resulting in increased serum iron and ferritin levels. Our data clearly demonstrate that elevated FGF23 is a causative factor in the development of renal anemia and iron deficiency, and importantly, blocking FGF23 signaling represents a novel approach to stimulate erythropoiesis and possibly improve survival for millions of chronic kidney disease patients worldwide.-Agoro, R., Montagna, A., Goetz, R., Aligbe, O., Singh, G., Coe, L. M., Mohammadi, M., Rivella, S., Sitara, D. Inhibition of fibroblast growth factor 23 (FGF23) signaling rescues renal anemia.

Ferric Citrate Decreases Fibroblast Growth Factor 23 and Improves Erythropoietin Responsiveness in Hemodialysis Patients

BACKGROUND

Serum phosphate and vitamin D receptor activator regulate fibroblast growth factor 23 (FGF23), and iron may modulate FGF23 metabolism. The aim of the present study was to elucidate the effects of ferric citrate hydrate and lanthanum carbohydrate on serum FGF23 levels in hemodialysis patients.

METHODS

This prospective, open-label, multicenter study enrolled 60 patients on hemodialysis treated with lanthanum carbonate. Patients were randomly assigned to 2 groups: those switching from lanthanum carbonate to ferric citrate hydrate (ferric citrate group, n = 30) or those continuing lanthanum carbonate (control group, n = 30). Patients were monitored for 24 weeks. Endpoints included changes in FGF23, phosphate, and the dose of erythropoiesis stimulating agent (ESA), erythropoietin responsiveness index (ERI), and adverse events.

RESULTS

FGF-23 levels were significantly lower in the ferric citrate group compared with the levels in the control group (change from baseline -6,160 vs. -1,118 pg/mL; p = 0.026). There were no significant changes in serum calcium, phosphate, and intact parathyroid hormone levels in either group. The ferric citrate group had significantly increased serum iron, ferritin, and transferrin saturation. Hemoglobin levels were significantly elevated, and the dose of ESA was significantly decreased in the ferric citrate group but not in the control group. ERI and the dose of intravenous saccharated ferric oxide were significantly lower in the ferric citrate group compared with those of the control group (p = 0.015 and p = 0.002).

CONCLUSION

In patients on hemodialysis, 24-week treatment with ferric citrate hydrate resulted in significant reduction in FGF23 and ERI independently of serum phosphate level.

[Correlation of fibroblast growth factor 23 with adverse prognosis of chronic kidney disease and therapy strategy]

Fibroblast growth factor 23 (FGF23) is a hormone secreted by the bone. It is not only involved in the pathophysiological process of chronic kidney disease (CKD), but also associated with the poor prognosis. In patients with CKD, serum FGF23 levels are elevated in early phase. The increased FGF23 levels gradually lead to myocardial hypertrophy, inflammatory, vascular calcification, and low level of vitamin D, which contribute to the progress of CKD, cardiovascular complications and even death. Presently, there are several ways to reduce FGF23 levels, including decrease of intake and block of phosphorus absorption, supplement of FGF23 antibody and pseudo calcium or renal transplantation.

Burosumab Therapy in Children with X-Linked Hypophosphatemia

BACKGROUND

X-linked hypophosphatemia is characterized by increased secretion of fibroblast growth factor 23 (FGF-23), which leads to hypophosphatemia and consequently rickets, osteomalacia, and skeletal deformities. We investigated burosumab, a monoclonal antibody that targets FGF-23, in patients with X-linked hypophosphatemia.

METHODS

In an open-label, phase 2 trial, we randomly assigned 52 children with X-linked hypophosphatemia, in a 1:1 ratio, to receive subcutaneous burosumab either every 2 weeks or every 4 weeks; the dose was adjusted to achieve a serum phosphorus level at the low end of the normal range. The primary end point was the change from baseline to weeks 40 and 64 in the Thacher rickets severity total score (ranging from 0 to 10, with higher scores indicating greater disease severity). In addition, the Radiographic Global Impression of Change was used to evaluate rachitic changes from baseline to week 40 and to week 64. Additional end points were changes in pharmacodynamic markers, linear growth, physical ability, and patient-reported outcomes and the incidence of adverse events.

RESULTS

The mean Thacher rickets severity total score decreased from 1.9 at baseline to 0.8 at week 40 with every-2-week dosing and from 1.7 at baseline to 1.1 at week 40 with every-4-week dosing (P<0.001 for both comparisons); these improvements persisted at week 64. The mean serum phosphorus level increased after the first dose in both groups, and more than half the patients in both groups had levels within the normal range (3.2 to 6.1 mg per deciliter [1.0 to 2.0 mmol per liter]) by week 6. Stable serum phosphorus levels were maintained through week 64 with every-2-week dosing. Renal tubular phosphate reabsorption increased from baseline in both groups, with an overall mean increase of 0.98 mg per deciliter (0.32 mmol per liter). The mean dose of burosumab at week 40 was 0.98 mg per kilogram of body weight with every-2-week dosing and 1.50 mg per kilogram with every-4-week dosing. Across both groups, the mean serum alkaline phosphatase level decreased from 459 U per liter at baseline to 369 U per liter at week 64. The mean standing-height z score increased in both groups, with greater improvement seen at all time points with every-2-week dosing (an increase from baseline of 0.19 at week 64) than with every-4-week dosing (an increase from baseline of 0.12 at week 64). Physical ability improved and pain decreased. Nearly all the adverse events were mild or moderate in severity.

CONCLUSIONS

In children with X-linked hypophosphatemia, treatment with burosumab improved renal tubular phosphate reabsorption, serum phosphorus levels, linear growth, and physical function and reduced pain and the severity of rickets. (Funded by Ultragenyx Pharmaceutical and Kyowa Hakko Kirin; ClinicalTrials.gov number, NCT02163577 ; EudraCT number, 2014-000406-35 ).

Ensemble docking to difficult targets in early-stage drug discovery: Methodology and application to fibroblast growth factor 23

Ensemble docking is now commonly used in early-stage in silico drug discovery and can be used to attack difficult problems such as finding lead compounds which can disrupt protein-protein interactions. We give an example of this methodology here, as applied to fibroblast growth factor 23 (FGF23), a protein hormone that is responsible for regulating phosphate homeostasis. The first small-molecule antagonists of FGF23 were recently discovered by combining ensemble docking with extensive experimental target validation data (Science Signaling, 9, 2016, ra113). Here, we provide a detailed account of how ensemble-based high-throughput virtual screening was used to identify the antagonist compounds discovered in reference (Science Signaling, 9, 2016, ra113). Moreover, we perform further calculations, redocking those antagonist compounds identified in reference (Science Signaling, 9, 2016, ra113) that performed well on drug-likeness filters, to predict possible binding regions. These predicted binding modes are rescored with the molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) approach to calculate the most likely binding site. Our findings suggest that the antagonist compounds antagonize FGF23 through the disruption of protein-protein interactions between FGF23 and fibroblast growth factor receptor (FGFR).

[Bone and calcium metabolism associated with malignancy. Tumor-induced osteomalacia.]

Tumor-induced osteomalacia(TIO)is a paraneoplastic syndrome caused by excessive production and secretion of fibroblast growth factor 23(FGF23)from causative tumors which induces hypophosphatemia and osteomalacia. Mesenchymal benign tumors in bone or soft tissue are the most frequent causes for TIO. The first choice treatment of TIO is complete resection of the responsible tumors. In patients whose tumors cannot be completely removed, phosphate salt and active vitamin D are usually prescribed. The effect of anti-FGF23 monoclonal antibody that inhibits the actions of FGF23 is being tested in clinical trials.

[Rickets/Osteomalacia. Anti-FGF23 antibody therapy in patients with FGF23-related hypophosphatemic rickets and osteomalacia.]

Fibroblast growth factor 23(FGF23)is a phosphaturic hormone, and its excess causes several kinds of congenital and acquired hypophosphatemic diseases. A combination of oral active vitamin D3 and phosphate salt is the current standard therapy for patients with FGF23-related hypophosphatemic rickets and osteomalacia. However, these medications may cause long-term complications, such as secondary hyperparathyroidism and chronic kidney disease. Therefore, an anti-FGF23 neutralizing antibody that blocks FGF23 activity has been produced. X-linked hypophosphatemic rickets(XLHR)is the most prevalent form of hereditary FGF23-related hypophosphatemia. The safety and efficacy of a human anti-FGF23 antibody, KRN23 or burosumab, has been confirmed in adults and children with XLHR. Moreover, Burosumab is being tested as a potential treatment for patients with tumor-induced osteomalacia(TIO), which is the most prevalent form of acquired FGF23-related hypophosphatemia.

Nymphaeol-C, a prenylflavonoid from Macaranga tanarius, suppresses the expression of fibroblast growth factor 18

BACKGROUND

Fibroblast growth factor 18 (FGF18) is one of the key factors in human signaling pathways and has been reported to be associated with the formation of various tissues. Additionally, FGF18 has been reported to maintain the telogen stage of the hair cycle, and its over-expression has also been observed in cancer cells.

HYPOTHESIS/PURPOSE

We searched for natural compounds that inhibit the expression of FGF18 expression in vitro and evaluated their inhibitory mechanisms.

STUDY DESIGN

Various plant samples were screened using a luciferase assay targeting FGF18. One active compound was selected by the screening, isolated and identified.

METHODS

The active compound was isolated using chromatographic techniques and identified by specific rotation measurements, LC-MS and NMR. Additionally, its inhibitory mechanism was evaluated using real-time RT-PCR and Western blotting.

RESULTS

As a result of screening various plant leaf samples, Macaranga tanarius was identified as the most active plant and a prenylflavonoid nymphaeol-C was isolated as the active compound. Using real-time RT-PCR and Western blotting analysis, this compound was confirmed to strongly suppress the expression of FGF18. The compound lowered the β-catenin level in the Wnt/β-catenin pathway. Thus, it was suggested that nymphaeol-C suppresses the expression of FGF18 by suppressing β-catenin expression. Additionally, the compound lowered the extracellular signal-regulated kinase1/2 (ERK1/2) phosphorylation level in the mitogen-activated protein kinase cascade (MAPK cascade). Therefore, nymphaeol-C suppressed downstream signals of FGF18 by suppressing the expression of FGF18.

CONCLUSION

We isolated and identified prenylflavonoid nymphaeol-C from M. tanarius. The compound suppresses the expression of FGF18 and affects FGF18 related signals.

Androgen Receptor Pathway-Independent Prostate Cancer Is Sustained through FGF Signaling

Androgen receptor (AR) signaling is a distinctive feature of prostate carcinoma (PC) and represents the major therapeutic target for treating metastatic prostate cancer (mPC). Though highly effective, AR antagonism can produce tumors that bypass a functional requirement for AR, often through neuroendocrine (NE) transdifferentiation. Through the molecular assessment of mPCs over two decades, we find a phenotypic shift has occurred in mPC with the emergence of an AR-null NE-null phenotype. These "double-negative" PCs are notable for elevated FGF and MAPK pathway activity, which can bypass AR dependence. Pharmacological inhibitors of MAPK or FGFR repressed the growth of double-negative PCs in vitro and in vivo. Our results indicate that FGF/MAPK blockade may be particularly efficacious against mPCs with an AR-null phenotype.

Sprouting strategies and dead ends in anti-angiogenic targeting of NETs

Neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms that arise from cells of the neuroendocrine system. NETs are characterized by being highly vascularized tumors that produce large amounts of proangiogenic factors. Due to their complexity and heterogeneity, progress in the development of successful therapeutic approaches has been limited. For instance, standard chemotherapy-based therapies have proven to be poorly selective for tumor cells and toxic for normal tissues. Considering the urge to develop an efficient therapy to treat NET patients, vascular targeting has been proposed as a new approach to block tumor growth. This review provides an update of the mechanisms regulating different components of vessels and their contribution to tumor progression in order to develop new therapeutic drugs. Following the description of classical anti-angiogenic therapies that target VEGF pathway, new angiogenic targets such as PDGFs, EGFs, FGFs and semaphorins are further explored. Based on recent research in the field, the combination of therapies that target multiple and different components of vessel formation would be the best approach to specifically target NETs and inhibit tumor growth.

Chemical inhibition reveals differential requirements of signaling pathways in krasV12- and Myc-induced liver tumors in transgenic zebrafish

Previously we have generated inducible liver tumor models by transgenic expression of an oncogene and robust tumorigenesis can be rapidly induced by activation of the oncogene in both juvenile and adult fish. In the present study, we aimed at chemical intervention of tumorigenesis for understanding molecular pathways of tumorigenesis and for potential development of a chemical screening tool for anti-cancer drug discovery. Thus, we evaluated the roles of several major signaling pathways in krasV12- or Myc-induced liver tumors by using several small molecule inhibitors: SU5402 and SU6668 for VEGF/FGF signaling; IWR1 and cardionogen 1 for Wnt signaling; and cyclopamine and Gant61 for Hedgehog signaling. Inhibition of VEGF/FGF signaling was found to deter both Myc- and krasV12-induced liver tumorigenesis while suppression of Wnt signaling relaxed only Myc- but not krasV12-induced liver tumorigenesis. Inhibiting Hedgehog signaling did not suppress either krasV12 or Myc-induced tumors. The suppression of liver tumorigenesis was accompanied with a decrease of cell proliferation, increase of apoptosis, distorted liver histology. Collectively, our observations suggested the requirement of VEGF/FGF signaling but not the hedgehog signaling in liver tumorigenesis in both transgenic fry. However, Wnt signaling appeared to be required for liver tumorigenesis only in Myc but not krasV12 transgenic zebrafish.