A Phase III, Multicenter, Randomized, Double-blind, Placebo-controlled, Parallel-group Study of 2 Dosing Regimens of Fostamatinib in Patients with Rheumatoid Arthritis with an Inadequate Response to a Tumor Necrosis Factor-α Antagonist

Objective.

Our 24-week study (NCT01197755; OSKIRA-3) compared the efficacy and safety of fostamatinib versus placebo in patients taking background methotrexate treatment with active rheumatoid arthritis (RA) and an inadequate response to a single tumor necrosis factor-α antagonist.

Methods.

Adult patients were randomized (1:1:1) to fostamatinib [100 mg bid for 24 weeks (n = 105; Group A)], or 100 mg bid for 4 weeks, then 150 mg qd (n = 108; Group B), or to placebo (n = 110; Group C) for 24 weeks. Nonresponders at Week 12 could enter a longterm extension study. The primary endpoint was the proportion of patients achieving an American College of Rheumatology 20% (ACR20) response at Week 24.

Results.

Baseline characteristics were well balanced. Significantly more patients in fostamatinib Group A (36.2%; p = 0.004), but not B (27.8%; p = 0.168), achieved ACR20 at Week 24 versus placebo (21.1%). Frequently reported adverse events were diarrhea, hypertension, and headache. Elevated blood pressure (≥ 140/90 mm Hg) at ≥ 1 visit was observed in 46.7%, 51.9%, and 26.6% of patients, respectively. There were 2 deaths in the study, 1 in Group B and 1 in the placebo group.

Conclusion.

Fostamatinib 100 mg bid, but not fostamatinib 100 mg bid for 4 weeks then 150 mg qd, achieved statistical improvements in ACR20 at 24 weeks versus placebo. Because of efficacy and safety results from the phase III clinical program, the companies developing fostamatinib have decided not to study it further in RA at this time.

Discovery of small molecular inhibitors targeting HIV-1 gp120-CD4 interaction drived from BMS-378806

The HIV-1 entry into host cells is a complex, multi-factors involved, and multi-step process. Especially, the attachment of HIV-1 envelope glycoprotein gp120 to the host cell receptor CD4 is the first key step during entry process, representing a promising antiviral therapeutic target. Among the HIV-1 attachment inhibitors blocking the interaction between gp120 and CD4 cells, BMS-378806 and NBD-556 are two representative small molecular chemical entities. Particularly, BMS-378806 and its derivatives are newly identified class of orally bioavailable HIV-1 inhibitors that interfere gp120-CD4 interaction. In this review, we focused on describing the structure-activity relationships (SARs), structural modifications, in vitro or even in vivo pharmacodynamics and pharmacokinetics of BMS-378806 and its analogues as HIV-1 gp120 attachment inhibitors. In addition, the brief SARs, structural modifications of NBD-556 and its derivatives targeting the "Phe-43 cavity" as CD4 mimics were also described.

OSKIRA-4: a phase IIb randomised, placebo-controlled study of the efficacy and safety of fostamatinib monotherapy

Objectives

OSKIRA-4 evaluated the efficacy of fostamatinib monotherapy versus placebo on the signs and symptoms of rheumatoid arthritis over 6 weeks by Disease Activity Score C reactive protein (DAS-28(CRP)) and assessed non-inferiority to adalimumab monotherapy at Week 24 by DAS-28(CRP).

Methods

Overall, 279 patients not currently taking disease-modifying antirheumatic drugs were randomised to: (A) fostamatinib 100 mg twice daily for 24 weeks plus placebo injection every 2 weeks (PBOI); (B) fostamatinib 100 mg twice daily for 4 weeks, then 150 mg once daily up to Week 24, plus PBOI; (C) fostamatinib 100 mg twice daily for 4 weeks, then 100 mg once daily up to Week 24, plus PBOI; (D) adalimumab 40 mg every 2 weeks for 24 weeks, plus oral placebo twice daily; or (E) oral placebo twice daily for 6 weeks, plus PBOI, then a switch to arm A or B.

Results

Fostamatinib demonstrated a significant improvement in DAS-28(CRP) score from baseline versus placebo at Week 6 for arms A and B, but not C. Fostamatinib was significantly less effective than adalimumab at Week 24 based on DAS-28(CRP). Adverse events observed with fostamatinib treatment were consistent with those reported in previous studies, including hypertension and diarrhoea.

Conclusions

Fostamatinib demonstrated efficacy as monotherapy, showing superior DAS-28(CRP) score changes between baseline and 6 weeks when compared with placebo in treatment arms A and B. However, all fostamatinib regimens demonstrated inferior responses compared with adalimumab at Week 24.

Trial registration number

Clinicaltrials.gov: NCT01264770.

Pharmacokinetics and efficacy of the spleen tyrosine kinase inhibitor r406 after ocular delivery for retinoblastoma

PURPOSE

Retinoblastoma is a childhood cancer of the retina. Clinical trials have shown that local delivery of broad spectrum chemotherapeutic agents is efficacious. Recent studies characterizing the genomic and epigenomic landscape of retinoblastoma identified spleen tyrosine kinase (SYK) as a promising candidate for targeted therapy. The purpose of this study was to conduct preclinical testing of the SYK antagonist R406 to evaluate it as a candidate for retinoblastoma treatment.

METHODS

The efficacy of the SYK antagonist R406 delivered locally in a human orthotopic xenograft mouse model of retinoblastoma was tested. Intraocular exposure of R406 was determined for various routes and formulations.

RESULTS

There was no evidence of efficacy for subconjunctival. R406. Maximal vitreal concentration was 10-fold lower than the minimal concentration required to kill retinoblastoma cells in vitro. Dosage of R406 subconjunctivally from emulsion or suspension formulations, direct intravitreal injection of the soluble prodrug of R406 (R788), and repeated topical administration of R406 all increased vitreal exposure, but failed to reach the exposure required for retinoblastoma cell death in culture.

CONCLUSION

Taken together, these data suggest that R406 is not a viable clinical candidate for the treatment of retinoblastoma. This study highlights the importance of pharmacokinetic testing of molecular targeted retinoblastoma therapeutics.

Pharmacokinetics of fostamatinib, a spleen tyrosine kinase (SYK) inhibitor, in healthy human subjects following single and multiple oral dosing in three phase I studies

AIM

Fostamatinib (R788) is an orally dosed prodrug designed to deliver the active metabolite R940406 (R406), a spleen tyrosine kinase (SYK) inhibitor, for the treatment of rheumatoid arthritis. The objectives were to evaluate the human pharmacokinetic properties of fostamatinib and R406.

METHOD

Three clinical studies were conducted in healthy subjects: (A) A single ascending dose study for R406 with doses ranging from 80-600 mg, (B) a single- and multiple-dose study of fostamatinib in aqueous suspension, with single doses ranging from 80-400 mg and multiple doses at 160 mg twice daily and (C) a study comparing suspension and tablet of fostamatinib, with the latter tested in both fed and fasted states.

RESULTS

These studies demonstrated that when administered as a solution, R406 was rapidly absorbed. Increases in exposure were observed with doses up to 400 mg. A terminal half-life of 12-21 h was observed. Similar R406 exposure could be achieved with fostamatinib suspension and steady-state was achieved after 3-4 days following twice daily administration. Fostamatinib tablet and suspension exhibited similar R406 exposure. Upon co-administration with food, a delay in peak time and lower peak concentrations of R406 were observed but at the same time the overall exposure did not change.

CONCLUSION

Fostamatinib demonstrates rapid and extensive conversion to R406, an inhibitor of SYK. Solid dosage forms of fostamatinib overcome the challenge of low aqueous solubility of R406. The PK profile of R406 could potentially allow once daily or twice daily oral administration of fostamatinib.

Fluorine-Containing Diazines in Medicinal Chemistry and Agrochemistry

The combination of a fluorine atom and a diazine ring, which both possess unique structural and chemical features, can generate new relevant building blocks for the discovery of efficient fluorinated biologically active agents. Herein we give a comprehensive review on the biological activity and synthesis of fluorine containing, pyrimidine, pyrazine and pyridazine derivatives with relevance to medicinal and agrochemistry.

The status of fostamatinib in the treatment of rheumatoid arthritis

Fostamatinib (R788) is a prodrug rapidly converted to its active metabolite on oral administration. This (known as R406) is a potent inhibitor of spleen tyrosine kinase, required for the expression of a number of proinflammatory cytokines. Fostamatinib has shown significantly superior efficacy (when compared with placebo) in the control of patients with rheumatoid arthritis not responding to methotrexate in Phase II clinical trials. Treatment emergent adverse events with a higher frequency than in those on placebo included diarrhea, hypertension, urinary tract infections, neutropenia and elevated transaminases. The studied doses have shown a linear pharmacokinetic pattern and the administration of methotrexate does not affect it. Fostamatinib may have a role in the therapy of patients with rheumatoid arthritis with poor response to conventional therapy. If these results are confirmed once Phase III studies are completed, it may find a place in the evolving treatment algorithm for rheumatoid arthritis.

A multi-histology trial of fostamatinib in patients with advanced colorectal, non-small cell lung, head and neck, thyroid, and renal cell carcinomas, and pheochromocytomas

PURPOSE

A multi-cohort phase II study of fostamatinib, an oral multi-kinase inhibitor, was conducted to determine the response rate in patients with advanced colorectal (CRC), thyroid, non-small cell lung, head and neck, and renal cell carcinomas, and pheochromocytomas.

METHODS

Patients received 200 mg fostamatinib BID in 4-week cycles with response assessed every 2 cycles. Blood was collected for pharmacokinetic analysis and measurements of circulating tumor cells and circulating endothelial (progenitor) cells (CE(P)Cs).

RESULTS

A total of 37 patients (22 CRC), median of 4 prior therapies, were enrolled. Due to toxicities in four of the first five patients, the study was amended to incorporate a dose escalation phase for each histology. The maximum-tolerated dose was established at 50 mg BID in CRC but was not established for the other cancers. Common grade 3/4 toxicities included transaminitis, hyperbilirubinemia, and hypertension. Pharmacokinetic profile was similar to previous reports. Seventy-three percent of CRC patients had liver involvement and 91 % had prior anti-angiogenic therapy. Patients with abnormal liver tests at baseline were more likely to experience grade ≥ 2 hepatotoxicity than those with normal tests (44 vs. 0 %). No responses were observed; disease stabilization rate was 27 % in CRC. Reduction in CECs following treatment was associated with a better disease stabilization rate (75 vs. 0 %) in CRC.

CONCLUSION

Fostamatinib had limited anti-tumor activity in this first clinical trial in patients with advanced refractory solid tumors; reduction in CECs and CEPs was indicative of anti-angiogenic effects. Abnormal liver testing at baseline appeared to influence drug tolerability.

Targeting kinases: a new approach to treating inflammatory rheumatic diseases

After two decades of research and development activity focussed on orally active kinase inhibitors, the first such drug (the JAK inhibitor Xeljanz, tofacitinib) was approved by the FDA in November 2012 for the treatment of rheumatoid arthritis (RA). There is an intense activity in many companies both on expanding the utility of JAK inhibitors in other auto-immune indications and in discovering inhibitors of the JAK family with different and more selective profiles. Progress is also being made with orally active Syk inhibitors. One such inhibitor (fostamatinib) is currently in large-scale phase 3 trials, and there are others in clinical development. The last two to three years have been transformative for kinase inhibitors in auto-immune diseases, as several inhibitors have finally progressed beyond phase 2 trials after so many failures on other targets. Thus, there are new treatment options for RA patients beyond existing oral DMARDs and parenteral biologics.

Challenges and opportunities of metabolomics

The metabolome is a data-rich source of information concerning all the low-molecular-weight metabolites in a biofluid, which can indicate early biological changes to the host due to perturbations in metabolic pathways. Major changes can be seen after minor stimuli, which make it a valuable target for analysis. Due to the diverse and sensitive nature of the metabolome, studies must be designed in a manner to maintain consistency, reduce variation between subjects, and optimize information recovery. Technological advancements in experimental design, mouse models and instrumentation have aided in this effort. Metabolomics has the ultimate potential to be valuable in a clinical setting where it could be used for early diagnosis of a disease and as a predictor of treatment response and survival. During drug treatment, the metabolic status of an individual could be monitored and used to indicate possible toxic effects. Metabolomics therefore has great potential for improving diagnosis, treatment and aftercare of disease.

Characterization of the metabolism of sibiricaxanthone F and its aglycone in vitro by high performance liquid chromatography coupled with Q-trap mass spectrometry

To explain the low bioavailability of sibiricaxanthone F (SF) following oral administration and to predict its possible metabolites in vivo, the in vitro biotransformation of SF and its metabolic stability in intestinal bacteria (BI) were studied. The metabolism of SF and its aglycone (1,3,6-trihydroxy-2,7-dimethoxyxanthone, Xan) was characterized after incubation with human and rat liver microsomes (HLMs and RLMs). The chemical structures of the metabolites were tentatively identified on the basis of their mass profiles using high performance liquid chromatography coupled with an enhanced mass spectrometry-information dependent acquisition-enhanced product ion (EMS-IDA-EPI) scan mode on a hybrid triple quadrupole-linear ion trap mass spectrometer. The metabolic stability of SF in BI was determined using the multiple reaction monitoring (MRM) mode. As a result, five hydrolyzed metabolites (M1-M4 and Xan) were generated stepwise for SF when it was incubated with BI, whereas two demethylated products (M1 and M5) were detected for Xan in BI. The metabolic stability study of SF in BI revealed that the parent compound could be rapidly hydrolyzed by BI and that Xan, the main corresponding metabolite, increased rapidly. In RLMs and HLMs, two hydrolyzed metabolites (M2 and M3) mediated by CYP450 isoenzymes appeared for SF in the presence of an NADPH-regenerating system, whereas no metabolite was detected for Xan under the same conditions. One (M6) and three glucuronidated metabolites (M7-M9) were generated from SF and Xan, respectively, by phase II isoenzymes in liver microsomal proteins in the presence of uridine 5'-diphosphoglucuronic acid (UDPGA). Overall, the present study revealed that extensive first-pass elimination occurred for SF in intestinal bacteria and hepatic subcellular proteins in vitro, which could be one of the main reasons for the low bioavailability of SF; furthermore, the possible SF-related metabolites in rats and humans were elucidated to be mono-glucuronidated derivatives of Xan following oral administration of SF.

Adjunctive TNF inhibition with standard treatment enhances bacterial clearance in a murine model of necrotic TB granulomas

BACKGROUND

It has been hypothesized that early host-responses during TB treatment may paradoxically promote survival of persistent bacteria. We therefore evaluated whether adjunctive inhibition of tumor necrosis factor alpha (TNF-α)-a key cytokine in host responses against TB-could hasten bacterial clearance in a mouse strain that develops necrotic lesions in response to Mycobacterium tuberculosis infection.

METHODOLOGY/PRINCIPAL FINDINGS

Six weeks after an aerosol infection, C3HeB/FeJ mice received standard TB treatment with or without adjunctive TNF inhibition (etanercept for the initial six weeks). Functional TNF-α levels and lung pathology were found to be reduced in the mice receiving etanercept. Compared to standard TB treatment, the addition of etanercept resulted in a significantly lower pulmonary bacterial burden, corresponding to the phase when a significant proportion of bacteria are multiplying slowly (p<0.0233). Finally, only 10.5% of mice receiving adjunctive etanercept versus 27.8% receiving standard TB treatment alone relapsed.

CONCLUSION

This study provides proof-of-principle that modulation of TNF-α activity can hasten bacterial clearance during standard multi-drug TB treatment. Oral agents that modulate TNF-α should therefore be considered as adjunct therapies for shortening TB treatments. However, due to concerns of reactivation disease, additional studies need to be performed before TNF-α inhibitors are used for TB treatment in humans.

Tyrosine kinase inhibitors as potential drugs for B-cell lymphoid malignancies and autoimmune disorders

INTRODUCTION

In the last few years, several tyrosine kinase inhibitors (TKIs) have been synthesized and become available for preclinical studies and clinical trials. This article summarizes recent achievements in the mechanism of action, pharmacological properties, and clinical activity and toxicity, as well as the emerging role of TKIs in lymphoid malignancies, allergic diseases, and autoimmune disorders.

AREAS COVERED

A literature review was conducted of the MEDLINE database PubMed for articles in English. Publications from 2000 through January 2012 were scrutinized. The search terms used were Bruton's tyrosine kinase (Btk) inhibitors, PCI-32765, GDC-0834, LFM-A13, AVL-101, AVL-292, spleen tyrosine kinase (Syk) inhibitors, R343, R406, R112, R788, fostamatinib, BAY-61-3606, C-61, piceatannol, Lyn, imatinib, nilotinib, bafetinib, dasatinib, GDC-0834, PP2, SU6656 in conjunction with lymphoid malignancy, NHL, CLL, autoimmune disease, allergic disease, asthma, and rheumatoid arthritis. Conference proceedings from the previous 5 years of the American Society of Hematology, European Hematology Association, American Society of Clinical Oncology, and ACR/ARHP Annual Scientific Meetings were searched manually. Additional relevant publications were obtained by reviewing the references from the chosen articles.

EXPERT OPINION

The use of TKIs, especially inhibitors of Btk, Syk, and Lyn, is a promising new strategy for targeted treatment of B-cell lymphoid malignancies, autoimmune disorders and allergic diseases. However, definitive data from ongoing and future clinical trials will aid in better defining the status of TKIs in the treatment of these disorders.

Inhibitors of human immunodeficiency virus type 1 (HIV-1) attachment 6. Preclinical and human pharmacokinetic profiling of BMS-663749, a phosphonooxymethyl prodrug of the HIV-1 attachment inhibitor 2-(4-benzoyl-1-piperazinyl)-1-(4,7-dimethoxy-1H-pyrrolo[2,3-c]pyridin-3-yl)-2-oxoethanone (BMS-488043)

BMS-663749, a phosphonooxymethyl prodrug 4 of the HIV-1 attachment inhibitor 2-(4-benzoyl-1-piperazinyl)-1-(4,7-dimethoxy-1H-pyrrolo[2,3-c]pyridin-3-yl)-2-oxoethanone (BMS-488043) (2) was prepared and profiled in a variety of preclinical in vitro and in vivo models designed to assess its ability to deliver parent drug following oral administration. The data showed that prodrug 4 had excellent potential to significantly reduce dissolution rate-limited absorption following oral dosing in humans. Clinical studies in normal healthy subjects confirmed the potential of 4, revealing that the prodrug significantly increased both the AUC and C(max) of 2 compared to a solid capsule formulation containing the parent drug upon dose escalation. These data provided guidance for further efforts to obtain an effective HIV-1 attachment inhibitor.

Role of spleen tyrosine kinase inhibitors in the management of rheumatoid arthritis

Spleen tyrosine kinase (Syk) is a cytoplasmic tyrosine kinase involved in signalling in many of the cells that drive immune inflammation. The development of small molecules that inhibit Syk kinase may change the way we treat disorders such as rheumatoid arthritis (RA), as well as a range of other inflammatory diseases. Fostamatinib (R-788) is an orally bioavailable small molecule. It is the prodrug of R406, which is a potent Syk inhibitor. Fostamatinib was developed because it has more favourable physiochemical properties. It is rapidly converted to R406 by intestinal enterocytes. It has been evaluated in experimental models of RA, such as collagen-induced arthritis. In these models, fostamatinib suppressed clinical arthritis, bone erosions, pannus formation and synovitis. A phase II programme with fostamatinib has largely been completed. Three key trials have been published, lasting 12-26 weeks and each enrolling 189-457 patients (875 in total). All these trials involved placebo therapy and patients continued to receive methotrexate in addition to active treatment with fostamatinib. The first dose-ranging trial evaluated three treatment doses in RA patients who had not fully responded to methotrexate therapy. The second trial compared two treatment doses in patients who had not responded to methotrexate therapy. The third trial compared a single treatment dose with placebo in patients who had not responded to biological therapy. The primary outcome measure was the number of patients achieving American College of Rheumatology (ACR) 20% (ACR20) responses. Placebo ACR20 response rates in all three trials were similar (35-38%). All three trials involved one treatment arm receiving fostamatinib 100 mg twice daily; ACR20 responses with this active treatment ranged from 38% to 67%. A meta-analysis of ACR responses in these trials, using responses to the highest dose in each trial for comparisons with placebo therapy in a random effects model, showed a borderline benefit with ACR20 responses. There were more significant differences with ACR50 and ACR70 responses. The reason that this meta-analysis was not more strongly positive is that the third trial, which evaluated patients who had failed to respond to biological treatments, gave negative results. Individual ACR response components, such as changes in swollen joint counts, showed significant differences in the first two trials, but there were no definite treatment benefits in the third trial. Overall, the differences were significant in a meta-analysis of all three trials. The most important adverse reactions were diarrhoea, neutropenia and raised ALT levels, which all showed significant excesses with active treatment compared with placebo. Too few patients have been studied for a definitive safety profile to be known. Overall, the results of the phase II trials were sufficiently encouraging for a phase III programme to be initiated. It will be some years before their definitive results are available.

Fostamatinib, a Syk-kinase inhibitor, does not affect methotrexate pharmacokinetics in patients with rheumatoid arthritis

Fostamatinib (R788) is being investigated as an add-on therapy for the treatment of rheumatoid arthritis (RA) in patients with inadequate response to methotrexate (MTX). This study evaluated the potential pharmacokinetic interaction between R788 and MTX. Sixteen RA subjects on a stable weekly MTX regimen were enrolled and received MTX on days 1 and 8. Twelve subjects received 100 mg of R788 orally, and 4 subjects received a matching placebo twice daily from days 4 to 8 and once daily on days 3 and 9. Blood samples were collected on days 1 and 8 for MTX and 7-hydroxymethotrexate (7-OH-MTX), and days 3 and 9 for R788 and its active metabolite, R406. MTX and 7-OH-MTX pharmacokinetic parameters were similar on days 1 and 8. In the R788 group, the mean day 8 to day 1 ratios (90% confidence intervals) of maximum concentration and area under the plasma concentration-time curve estimates were 1.01 (0.85-1.20) and 1.12 (0.90-1.40) for MTX and 1.06 (0.82-1.35) and 1.06 (0.83-1.36) for 7-OH-MTX, respectively. Urinary excretion of MTX and 7-OH-MTX was also similar with or without R788, averaging 58% to 69% and 4% to 5% of the MTX dose, respectively. The data suggest that there is no clinically significant pharmacokinetic interaction of R788 and MTX in RA patients.

Fostamatinib Disodium

The non-receptor tyrosine kinase Syk has a diverse range of biological functions, including a critical role in the intracellular signalling cascade for the surface immunoglobulin receptor on B lymphocytes, and the Fc receptor expressed on numerous immune effector cells. It is therefore seen as a potential therapeutic target in a variety of conditions, including autoimmune, allergic and malignant diseases. Fostamatinib disodium is the orally bioavailable prodrug of R406, a relatively selective small molecule inhibitor of Syk, that has accordingly shown activity in numerous cell types in vitro, and efficacy in a remarkable range of animal models in vivo, including rodent models of asthma, inflammatory arthritis, lupus, glomerulonephritis, diabetes and lymphoma. Success in these models has translated to phase II clinical trials in autoimmune thrombocytopenia, lymphoma and, most notably, rheumatoid arthritis, in which larger phase III trials are currently in progress. Whilst the diverse biological functions of Syk, coupled to the potential off-target effects of this kinase inhibitor are a source of possible toxicity, the available data thus far augurs well for future clinical use of Fostamatinib in a wide range of human diseases.