Phase 1 dose escalation trial of ilorasertib, a dual Aurora/VEGF receptor kinase inhibitor, in patients with hematologic malignancies

BACKGROUND

Ilorasertib (ABT-348) is a novel inhibitor of Aurora kinase, vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptors, and the Src families of tyrosine kinases. Ilorasertib alone or in combination with azacitidine demonstrated activity in preclinical models in various hematological malignancies, indicating that pan-Aurora kinase and multiple kinase inhibition may have preferential antileukemic activity. This phase 1 trial determined the safety, pharmacokinetics, and preliminary antitumor activity of ilorasertib alone or combined with azacitidine in advanced hematologic malignancies.

PATIENTS AND METHODS

Fifty-two patients (median age, 67 years; 35 % with >4 prior regimens) with acute myelogenous leukaemia (AML; n = 38), myelodysplastic syndrome (n = 12), or chronic myelomonocytic leukaemia (n = 2) received 3 or 6 doses of ilorasertib per 28-day cycle and were assigned to arm A (once-weekly oral), B (twice-weekly oral), C (once-weekly oral plus azacitidine), or D (once-weekly intravenous) treatment.

RESULTS

Maximum tolerated doses were not determined; the recommended phase 2 oral monotherapy doses were 540 mg once weekly and 480 mg twice weekly. The most common grade 3/4 adverse events were hypertension (28.8 %), hypokalemia (15.4 %), anemia (13.5 %), and hypophosphatemia (11.5 %). Oral ilorasertib pharmacokinetics appeared dose proportional, with a 15-hour half-life and no interaction with azacitidine. Ilorasertib inhibited biomarkers for Aurora kinase and VEGF receptors, and demonstrated clinical responses in 3 AML patients.

CONCLUSIONS

Ilorasertib exhibited acceptable safety and pharmacokinetics at or below the recommended phase 2 dose, displayed evidence of dual Aurora kinase and VEGF receptor kinase inhibition, and activity in AML.

Randomized phase II study of carboplatin and paclitaxel with either linifanib or placebo for advanced nonsquamous non-small-cell lung cancer

PURPOSE

Linifanib, a potent, selective inhibitor of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptors, has single-agent activity in non-small-cell lung cancer (NSCLC). We evaluated linifanib with carboplatin and paclitaxel as first-line therapy of advanced nonsquamous NSCLC.

PATIENTS AND METHODS

Patients with stage IIIB/IV nonsquamous NSCLC were randomly assigned to 3-week cycles of carboplatin (area under the curve 6) and paclitaxel (200 mg/m(2)) with daily placebo (arm A), linifanib 7.5 mg (arm B), or linifanib 12.5 mg (arm C). The primary end point was progression-free survival (PFS); secondary efficacy end points included overall survival (OS) and objective response rate.

RESULTS

One hundred thirty-eight patients were randomly assigned (median age, 61 years; 57% men; 84% smokers). Median PFS times were 5.4 months (95% CI, 4.2 to 5.7 months) in arm A (n = 47), 8.3 months (95% CI, 4.2 to 10.8 months) in arm B (n = 44), and 7.3 months (95% CI, 4.6 to 10.8 months) in arm C (n = 47). Hazard ratios (HRs) for PFS were 0.51 for arm B versus A (P = .022) and 0.64 for arm C versus A (P = .118). Median OS times were 11.3, 11.4, and 13.0 months in arms A, B, and C, respectively. HRs for OS were 1.08 for arm B versus A (P = .779) and 0.88 for arm C versus A (P = .650). Both linifanib doses were associated with increased toxicity, including a higher incidence of adverse events known to be associated with VEGF/PDGF inhibition. Baseline plasma carcinoembryonic antigen/cytokeratin 19 fragments biomarker signature was associated with PFS improvement and a trend toward OS improvement with linifanib 12.5 mg.

CONCLUSION

Addition of linifanib to chemotherapy significantly improved PFS (arm B), with a modest trend for survival benefit (arm C) and increased toxicity reflective of known VEGF/PDGF inhibitory effects.

Extracellular matrix mineralization in murine MC3T3-E1 osteoblast cultures: an ultrastructural, compositional and comparative analysis with mouse bone

Bone cell culture systems are essential tools for the study of the molecular mechanisms regulating extracellular matrix mineralization. MC3T3-E1 osteoblast cell cultures are the most commonly used in vitro model of bone matrix mineralization. Despite the widespread use of this cell line to study biomineralization, there is as yet no systematic characterization of the mineral phase produced in these cultures. Here we provide a comprehensive, multi-technique biophysical characterization of this cell culture mineral and extracellular matrix, and compare it to mouse bone and synthetic apatite mineral standards, to determine the suitability of MC3T3-E1 cultures for biomineralization studies. Elemental compositional analysis by energy-dispersive X-ray spectroscopy (EDS) showed calcium and phosphorus, and trace amounts of sodium and magnesium, in both biological samples. X-ray diffraction (XRD) on resin-embedded intact cultures demonstrated that similar to 1-month-old mouse bone, apatite crystals grew with preferential orientations along the (100), (101) and (111) mineral planes indicative of guided biogenic growth as opposed to dystrophic calcification. XRD of crystals isolated from the cultures revealed that the mineral phase was poorly crystalline hydroxyapatite with 10 to 20nm-sized nanocrystallites. Consistent with the XRD observations, electron diffraction patterns indicated that culture mineral had low crystallinity typical of biological apatites. Fourier-transform infrared spectroscopy (FTIR) confirmed apatitic carbonate and phosphate within the biological samples. With all techniques utilized, cell culture mineral and mouse bone mineral were remarkably similar. Scanning (SEM) and transmission (TEM) electron microscopy showed that the cultures had a dense fibrillar collagen matrix with small, 100nm-sized, collagen fibril-associated mineralization foci which coalesced to form larger mineral aggregates, and where mineralized sites showed the accumulation of the mineral-binding protein osteopontin. Light microscopy, confocal microscopy and three-dimensional reconstructions showed that some cells had dendritic processes and became embedded within the mineral in an osteocyte-like manner. In conclusion, we have documented characteristics of the mineral and matrix phases of MC3T3-E1 osteoblast cultures, and have determined that the structural and compositional properties of the mineral are highly similar to that of mouse bone.

Linifanib versus Sorafenib in patients with advanced hepatocellular carcinoma: results of a randomized phase III trial

PURPOSE

This open-label phase III trial evaluated efficacy and tolerability of linifanib versus sorafenib in patients with advanced hepatocellular carcinoma (HCC) without prior systemic therapy.

PATIENTS AND METHODS

Patients were randomly assigned in a 1:1 ratio to linifanib 17.5 mg once daily or sorafenib 400 mg twice daily. Patients were stratified by region (Outside Asia, Japan, and rest of Asia), Eastern Cooperative Oncology Group performance score (ECOG PS; 0 or 1), vascular invasion or extrahepatic spread (yes or no), and hepatitis B virus (HBV) infection (yes or no). The primary end point of the study was overall survival (OS). Secondary end points were time to progression (TTP) and objective response rate (ORR) per RECIST v1.1.

RESULTS

We randomly assigned 1,035 patients (median age, 60 years; Asian, 66.6%; ECOG PS 0, 65.2%; HBV, 49.1%; vascular invasion or extrahepatic spread, 70.1%). Median OS was 9.1 months on the linifanib arm (95% CI, 8.1 to 10.2) and 9.8 months on the sorafenib arm (95% CI, 8.3 to 11.0; hazard ratio [HR], 1.046; 95% CI, 0.896 to 1.221). For prespecified stratification subgroups, OS HRs ranged from 0.793 to 1.119 and the 95% CI contained 1.0. Median TTP was 5.4 months on the linifanib arm (95% CI, 4.2 to 5.6) and 4.0 months on the sorafenib arm (95% CI, 2.8 to 4.2; HR, 0.759; 95% CI, 0.643 to 0.895; P = .001). Best response rate was 13.0% on the linifanib arm versus 6.9% on the sorafenib arm. Grade 3/4 adverse events (AEs); serious AEs; and AEs leading to discontinuation, dose interruption, and reduction were more frequent with linifanib (all P < .001).

CONCLUSION

Linifanib and sorafenib had similar OS in advanced HCC. Predefined superiority and noninferiority OS boundaries were not met for linifanib and the study failed to meet the primary end point. TTP and ORR favored linifanib; safety results favored sorafenib.

Randomized phase II open-label study of mFOLFOX6 in combination with linifanib or bevacizumab for metastatic colorectal cancer

BACKGROUND

Although CRC is the third most commonly diagnosed cancer in the United States, second-line CRC treatment is limited. In this trial we examined the efficacy and safety of linifanib, an oral, potent, selective tyrosine kinase inhibitor of vascular endothelial growth factor and platelet-derived growth factor receptor families, with mFOLFOX6, compared with bevacizumab and mFOLFOX6, in previously treated metastatic CRC.

PATIENTS AND METHODS

One hundred forty-eight patients with advanced CRC previously treated with fluoropyrimidine or irinotecan received bevacizumab (10 mg/kg, intravenous), low-dose linifanib (7.5 mg), or high-dose linifanib (12.5 mg), with mFOLFOX6. The primary end point was progression-free survival (PFS). Secondary objectives included overall survival (OS), objective response rate (ORR), and safety.

RESULTS

No statistically significant differences in PFS occurred between bevacizumab and linifanib doses (low, hazard ratio [HR], 1.453 [95% confidence interval [CI], 0.830-2.539]; high, HR, 1.257 [95% CI, 0.672-2.351]). Median OS values were similar for bevacizumab and high-dose linifanib (bevacizumab, 16.5 months [95% CI, 13.0-not available]; high-dose linifanib, 16.4 months [95% CI, 11.9-21.7]; low-dose linifanib, 12.0 months [95% CI, 10.1-13.0]). ORRs were similar (bevacizumab, 34.7% [95% CI, 21.7-49.6]; low-dose linifanib, 24.0% [95% CI, 13.1-38.2]; high-dose linifanib, 22.4% [95% CI, 11.8-36.6]). Median cycles of 5-fluorouracil were reduced in the linifanib arms, versus the bevacizumab arm. Grade 3/4 adverse event occurrences were more frequent with linifanib. Palmar-plantar erythrodysesthesia, hypothyroidism, and thrombocytopenia were more common with high-dose linifanib than bevacizumab.

CONCLUSION

Combining linifanib with mFOLFOX6 as a second-line treatment for metastatic CRC did not improve PFS, radiographic findings, or duration of response versus bevacizumab and mFOLFOX6.

A phase 1 study of linifanib in combination with carboplatin/paclitaxel as first-line treatment of Japanese patients with advanced or metastatic non-small cell lung cancer (NSCLC)

INTRODUCTION

Linifanib is a potent, orally active, and selective inhibitor of vascular endothelial growth factor and platelet-derived growth factor receptor kinase activities with clinical efficacy in non-small cell lung cancer (NSCLC). This phase 1 dose-escalation study evaluated the pharmacokinetics, safety, and efficacy of linifanib in combination with carboplatin/paclitaxel in Japanese patients with advanced NSCLC.

METHODS

Carboplatin (AUC = 6 mg/mL/min) and paclitaxel (200 mg/m²) were administered on day 1 of each 21-day cycle up to a maximum of six cycles. Oral linifanib (7.5 mg) was given to six patients once daily throughout all cycles and escalated to 12.5 mg/day in a second cohort of six patients.

RESULTS

Twelve patients received at least one dose of linifanib. The most common adverse events were hematologic and consistent with expected toxicities with carboplatin/paclitaxel. With 12.5 mg linifanib, grade 3/4 neutropenia, leukopenia, and thrombocytopenia occurred in 100, 83, and 83 % of patients, respectively. Dose-limiting grade 4 thrombocytopenia occurred in one patient at each dose level. Linifanib pharmacokinetics was similar to that in non-Japanese patients. At 12.5 mg, linifanib Cmax was 0.32 μg/mL and AUC₂₄ was 4.29 μg h/mL. Linifanib Cmax occurred at 2-3 h with both doses and when given alone or in combination with carboplatin/paclitaxel. Exposure to linifanib appeared to be increased by carboplatin/paclitaxel, and exposure to paclitaxel appeared to be increased by linifanib. Partial responses were observed in nine patients.

CONCLUSIONS

Linifanib added to carboplatin/paclitaxel is well tolerated in Japanese patients with advanced/metastatic NSCLC. The recommended dose of linifanib with carboplatin/paclitaxel is 12.5 mg, same as for US patients.

Compounded PHOSPHO1/ALPL deficiencies reduce dentin mineralization

Phosphatases are involved in bone and tooth mineralization, but their mechanisms of action are not completely understood. Tissue-nonspecific alkaline phosphatase (TNAP, ALPL) regulates inhibitory extracellular pyrophosphate through its pyrophosphatase activity to control mineral propagation in the matrix; mice without TNAP lack acellular cementum, and have mineralization defects in dentin, enamel, and bone. PHOSPHO1 is a phosphatase found within membrane-bounded matrix vesicles in mineralized tissues, and double ablation of Alpl and Phospho1 in mice leads to a complete absence of skeletal mineralization. Here, we describe mineralization abnormalities in the teeth of Phospho1(-/-) mice, and in compound knockout mice lacking Phospho1 and one allele of Alpl (Phospho1(-/-);Alpl(+/-) ). In wild-type mice, PHOSPHO1 and TNAP co-localized to odontoblasts at early stages of dentinogenesis, coincident with the early mineralization of mantle dentin. In Phospho1 knockout mice, radiography, micro-computed tomography, histology, and transmission electron microscopy all demonstrated mineralization abnormalities of incisor dentin, with the most remarkable findings being reduced overall mineralization coincident with decreased matrix vesicle mineralization in the Phospho1(-/-) mice, and the almost complete absence of matrix vesicles in the Phospho1(-/-);Alpl(+/-) mice, whose incisors showed a further reduction in mineralization. Results from this study support prominent non-redundant roles for both PHOSPHO1 and TNAP in dentin mineralization.

Latissimus dorsi tendon transfer for irreparable tears of the rotator cuff: An anatomical study to assess the neurovascular hazards and ways of improving tendon excursion

Latissimus dorsi tendon transfer (LDTT) is technically challenging. In order to clarify the local structural anatomy, we undertook a morphometric study using six complete cadavers (12 shoulders). Measurements were made from the tendon to the nearby neurovascular structures with the arm in two positions: flexed and internally rotated, and adducted in neutral rotation. The tendon was then transferred and measurements were taken from the edge of the tendon to a reference point on the humeral head in order to assess the effect of a novel two-stage release on the excursion of the tendon. With the shoulder flexed and internally rotated, the mean distances between the superior tendon edge and the radial nerve, brachial artery, axillary nerve and posterior circumflex artery were 30 mm (26 to 34), 28 mm (17 to 39), 21 mm (12 to 28) and 15 mm (10 to 21), respectively. The mean distance between the inferior tendon edge and the radial nerve, brachial artery and profunda brachii artery was 18 mm (8 to 27), 22 mm (15 to 32) and 14 mm (7 to 21), respectively. Moving the arm to a neutral position reduced these distances. A mean of 15 mm (8 to 21) was gained from a standard soft-tissue release, and 32 mm (20 to 45) from an extensile release. These figures help to define further the structural anatomy of this region and the potential for transfer of the latissimus dorsi tendon.

Phase I study of ABT-888 in combination with carboplatin and gemcitabine in subjects with advanced solid tumors

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Background: Veliparib (V) is an oral inhibitor of poly(ADP-ribose) polymerases (PARP)-1 and -2, which are essential for base excision repair of ssDNA breaks. BRCA deficient tumors are more sensitive to PARP inhibitors when used as monotherapy or in combination with DNA-damaging agents. The objectives of this study were to determine the maximum tolerated dose (MTD), pharmacokinetic interactions, and safety/tolerability profile of V in combination with carboplatin (C) and gemcitabine (G). Methods: Eligibility criteria included patients (pts) with metastatic or unresectable solid tumors for which C/G was a treatment option. During the study, eligibility was amended to limit prior chemotherapy regimens to ≤ 2. C AUC 4 /G 800 mg/m2was given intravenously on Day 1 and G given on Day 8 of 21 day cycles. To assess tolerability of C/G prior to V, V was started in Cycle 2. When C/G was stopped, pts could stay on monotherapy V until progression. Dose-escalation used a Bayesian continual reassessment method. Results: 59 pts (51 female, median age 52) were enrolled. The most common tumor types were ovarian (n=39) and breast (n=10). Germline BRCA mutations were known in 24 ovarian pts. 58 pts had prior chemotherapy (1-6 regimens, median 2), and 51 had prior platinum. Grade 3/4 AEs in >10% of pts were neutropenia, thrombocytopenia, anemia, and leukopenia. Dose limiting toxicities were thrombocytopenia (n=3) and neutropenia at V 310 mg twice daily (BID) and thrombocytopenia at 250 mg BID. Other frequent AEs were nausea, constipation, and fatigue. Preliminary results showed co-administration of V did not affect C or G pharmacokinetics. Treatment cycles (range, median) were 1-28, 5 for V; 2-10, 5 for C; and 2-10, 4 for G. Day 8 G was stopped in some pts to improve tolerability. 28 pts stayed on monotherapy V (1-23 cycles). Partial and complete responses were seen in 11 and 2 pts. Response rates were 47% (8/17) in known BCRA deficient ovarian, 25% (3/12) in other ovarian, and 13% (2/15) in other evaluable pts. Conclusions: V combined with C and G was tolerated with a safety profile similar to C and G alone. The MTD was V 250 mg BID, C AUC 4.0, G 800 mg/m2. Promising anti-tumor activity was observed in BRCA deficient ovarian pts. Clinical trial information: NCT01063816.

Mineralization of dense collagen hydrogel scaffolds by human pulp cells

While advances in biomineralization have been made in recent years, unanswered questions persist on bone- and tooth-cell differentiation, on outside-in signaling from the extracellular matrix, and on the link between protein expression and mineral deposition. In the present study, we validate the use of a bioengineered three-dimensional (3D) dense collagen hydrogel scaffold as a cell-culture model to explore these questions. Dental pulp progenitor/stem cells from human exfoliated deciduous teeth (SHEDs) were seeded into an extracellular matrix-like collagen gel whose fibrillar density was increased through plastic compression. SHED viability, morphology, and metabolic activity, as well as scaffold mineralization, were investigated over 24 days in culture. Additionally, measurements of alkaline phosphatase enzymatic activity, together with immunoblotting for mineralized tissue cell markers ALPL (tissue-non-specific alkaline phosphatase), DMP1 (dentin matrix protein 1), and OPN (osteopontin), demonstrated osteo/odontogenic cell differentiation in the dense collagen scaffolds coincident with mineralization. Analyses of the mineral phase by electron microscopy, including electron diffraction and energy-dispersive x-ray spectroscopy, combined with Fourier-transform infrared spectroscopy and biochemical analyses, were consistent with the formation of apatitic mineral that was frequently aligned along collagen fibrils. In conclusion, use of a 3D dense collagen scaffold promoted SHED osteo/odontogenic cell differentiation and mineralization.

Phase III trial of linifanib versus sorafenib in patients with advanced hepatocellular carcinoma (HCC)

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Background: Linifanib (ABT-869; Lin) is a potent and selective inhibitor of the vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor tyrosine kinase families. In a phase II trial in patients (pts) with advanced HCC, Lin showed clinical activity (objective response rate [ORR] 10.5% in Child-Pugh A [CPA] pts). This open-label, global phase 3 trial evaluated Lin versus sorafenib (Sor) as first-line therapy in pts with advanced CPA HCC (NCT01009593). Methods: Pts were randomized 1:1 to Lin 17.5 mg QD or Sor 400 mg BID and stratified by region (non-Asia/Japan/rest of Asia), ECOG performance status (0/1), vascular invasion or extrahepatic spread (yes/no) and HBV infection (yes/no). The primary efficacy endpoint was overall survival (OS); both non-inferiority (margin 1.0491) and superiority hypotheses were to be tested. Secondary efficacy endpoints included time to progression (TTP) and ORR, using RECIST v1.1. AE severity was graded using NCI-CTCAE v4.0. Results: 1035 pts (median age 60 y, 68% Asian, 65% ECOG 0, 49% HBV, 70% vascular invasion or extrahepatic spread) were randomized at 149 sites in 26 countries. Hazard ratio (HR) for OS was 1.046 (95% CI: 0.896, 1.221). Median OS (95% CI) was 9.1 months (m) (8.1, 10.2) on Lin and 9.8 m (8.3, 11.0) on Sor. For all pre-specifed subgroup analyses, OS HRs ranged from 0.793-1.119, and the 95% CI contained 1.0. TTP HR was 0.759 (95% CI: 0.643, 0.895; p=0.001) favoring Lin. Median TTP (95% CI) was 5.4 m (4.2, 5.6) on Lin and 4.0 m (2.8. 4.2) on Sor. ORR was 13.0% on Lin and 6.9% on Sor. Grade 3/4 AEs, serious AEs and AEs leading to discontinuations, dose interruptions and reductions were more frequent on Lin versus Sor (all p<0.001). Conclusions: Lin and Sor resulted in similar OS in advanced HCC. Predefined superiority and non-inferiority OS boundaries were not met for Lin. Secondary endpoints (TTP and ORR) favored Lin while safety results favored Sor. Clinical trial information: NCT01009593.

Tooth root dentin mineralization defects in a mouse model of hypophosphatasia

Tissue-nonspecific alkaline phosphatase (TNAP) is expressed in mineralizing tissues and functions to reduce pyrophosphate (PP(i) ), a potent inhibitor of mineralization. Loss of TNAP function causes hypophosphatasia (HPP), a heritable disorder marked by increased PP(i) , resulting in rickets and osteomalacia. Tooth root cementum defects are well described in both HPP patients and in Alpl(-/-) mice, a model for infantile HPP. In Alpl(-/-) mice, dentin mineralization is specifically delayed in the root; however, reports from human HPP patients are variable and inconsistent regarding dentin defects. In the current study, we aimed to define the molecular basis for changes in dentinogenesis observed in Alpl(-/-) mice. TNAP was found to be highly expressed by mature odontoblasts, and Alpl(-/-) molar and incisor roots featured defective dentin mineralization, ranging from a mild delay to severely disturbed root dentinogenesis. Lack of mantle dentin mineralization was associated with disordered and dysmorphic odontoblasts having disrupted expression of marker genes osteocalcin and dentin sialophosphoprotein. The formation of, initiation of mineralization within, and rupture of matrix vesicles in Alpl(-/-) dentin matrix was not affected. Osteopontin (OPN), an inhibitor of mineralization that contributes to the skeletal pathology in Alpl(-/-) mice, was present in the generally unmineralized Alpl(-/-) mantle dentin at ruptured mineralizing matrix vesicles, as detected by immunohistochemistry and by immunogold labeling. However, ablating the OPN-encoding Spp1 gene in Alpl(-/-) mice was insufficient to rescue the dentin mineralization defect. Administration of bioengineered mineral-targeting human TNAP (ENB-0040) to Alpl(-/-) mice corrected defective dentin mineralization in the molar roots. These studies reveal that TNAP participates in root dentin formation and confirm that reduction of PP(i) during dentinogenesis is necessary for odontoblast differentiation, dentin matrix secretion, and mineralization. Furthermore, these results elucidate developmental mechanisms underlying dentin pathology in HPP patients, and begin to explain the reported variability in the dentin/pulp complex pathology in these patients.

Cohesive behavior of soft biological adhesives: experiments and modeling

Extracellular proteins play a key role in generating and maintaining cohesion and adhesion in biological tissues. These "natural glues" are involved in vital biological processes such as blood clotting, wound healing and maintaining the structural integrity of tissues. Macromolecular assemblies of proteins can be functionally stabilized in a variety of ways in situ that include ionic interactions as well as covalent crosslinking to form protein networks that can extend both within and between tissues. Within tissues, myriad cohesive forces are required to preserve tissue integrity and function, as are additional appropriate adhesive forces at interfaces both within and between tissues of differing composition. While the mechanics of some key structural adhesive proteins have been characterized in tensile experiments at both the macroscopic and single protein levels, the fracture toughness of thin proteinaceous interfaces has never been directly measured. Here, we describe a novel and simple approach to measure the cohesive behavior and toughness of thin layers of proteinaceous adhesives. The test is based on the standard double-cantilever beam test used for engineering adhesives, which was adapted to take into account the high compliance of the interface compared with the beams. This new "rigid double-cantilever beam" method enables stable crack propagation through an interfacial protein layer, and provides a direct way to measure its full traction-separation curve. The method does not require any assumption of the shape of the cohesive law, and the results provide abundant information contributing to understanding the structural, chemical and molecular mechanisms acting in biological adhesion. As an example, results are presented using this method for thin films of fibrin-a protein involved in blood clotting and used clinically as a tissue bio-adhesive after surgery-with the effects of calcium and crosslinking by Factor XIII being examined. Finally, a simple model is proposed, demonstrating how a bell-shaped cohesive law forms during the failure of the fibrin interface based on an eight-chain model whose structure degrades and changes configuration with stress.

Randomized phase II open-label study of mFOLFOX6 in combination with linifanib or bevacizumab for metastatic colorectal cancer

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Background: Linifanib is a potent and selective inhibitor of VEGF/PDGF receptors. This trial assessed the efficacy and safety of mFOLFOX6 in combination with linifanib or bevacizumab as second-line treatment for metastatic colorectal cancer (mCRC). Methods: Patients (pts) with measurable mCRC refractory to 1 prior regimen and ECOG PS 0–1, stratified by prior bevacizumab treatment and radiotherapy, were randomized to receive mFOLFOX6 with bevacizumab 10 mg/kg on day (d) 1 of 14-d cycle (Arm A), mFOLFOX6 with daily linifanib 7.5 mg (Arm B), or mFOLFOX6 with daily linifanib 12.5 mg (Arm C). The primary endpoint was progression-free survival (PFS). Severity of adverse events (AEs) was graded using NCI-CTCAE v3.0. Results: 148 pts were randomized at 45 sites in 14 countries. 32 pts (21.6%) had received prior bevacizumab. PFS and response data are shown below (Table). Median survival (OS) was not reached at median follow up 7.6 months. Palmar-plantar erythrodysesthesia (PPE) was the only Grade 3/4 AE significantly higher on linifanib (high dose, 16.3%) vs. bevacizumab (0%). Rate of any Grade 3+ AE was significantly higher on linifanib vs. bevacizumab.Hypertension rates were 41.7% (Arm A), 40.0% (Arm B), and 36.7% (Arm C). AEs dose-related to linifanib were constipation, proctalgia, stomatitis, fatigue, weight decrease, decreased appetite, and PPE. Conclusions: The addition of linifanib to mFOLFOX6, compared to mFOLFOX6 + bevacizumab, did not provide a PFS advantage for mCRC. OS results will be updated for conference presentation. [Table: see text]

Randomized phase II study of carboplatin and paclitaxel with either linifanib or placebo for advanced nonsquamous NSCLC

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Background: Linifanib is a potent and selective inhibitor of VEGF and PDGF receptors with modest single-agent activity in NSCLC. We evaluated the combination of linifanib with carboplatin (C) and paclitaxel (P) for first-line therapy of advanced non-squamous NSCLC. Methods: Patients (pts) with stage IIIB/IV, non-squamous NSCLC, stratified by ECOG PS and gender, were randomized to receive up to six 3-wk cycles of C (AUC 6 mg/ml/min) and P (200 mg/m2) with daily placebo (Arm A), linifanib 7.5 mg (Arm B), or linifanib 12.5 mg (Arm C). The primary endpoint was progression-free survival (PFS); secondary endpoints included overall survival (OS), 12 m survival rate, and objective response rate (ORR). Safety was assessed by NCI-CTCAE v3.0. Results: 138 pts were randomized at 37 sites in 6 countries. Baseline characteristics were: median age, 61 y; men, 57%; smoker, 84%. Efficacy results are shown in the table. Thrombocytopenia was the only Grade 3/4 AE significantly higher on linifanib (Arm B: 16.7%; Arm C: 29.8%) vs. placebo (2.1%). Other adverse events (AEs) related to the dose of linifanib were diarrhea, thrombocytopenia, hypertension, weight loss, palmar-plantar erythrodysaesthesia syndrome, and hypothyroidism. Analysis of samples for predictive biomarkers including serum VEGF and placental growth factor are underway. Conclusions: The addition of linifanib to chemotherapy was tolerable at the doses tested and resulted in a significant improvement in PFS, with a modest survival improvement for Arm C in first-line therapy of advanced non-squamous NSCLC. [Table: see text]

Association of baseline plasma biomarker signature with survival in advanced NSCLC patients on linifanib

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Background: Linifanib is a potent and selective VEGF and PDGF receptor inhibitor that has activity in unselected, advanced NSCLC patients (pts) both as monotherapy in the relapsed setting and with carboplatin (C) and paclitaxel (P) in the first-line setting. A baseline plasma biomarker signature identifying NSCLC pts most sensitive to linifanib is needed. Methods: An exploratory retrospective analysis of four randomized clinical trials including linifanib or other treatments in relapsed NSCLC was conducted. Evaluable baseline plasma samples were obtained from 116 pts who received linifanib and 71 pts on other treatments. A signature combining established tumor markers (carcinoembryonic antigen [CEA] and fragments of cytokeratin 19 [CYFRA 21-1]) was derived using a sequential BATTing approach. The signature was then tested across a randomized trial of CP + placebo, linifanib 7.5 mg, or linifanib 12.5 mg in first-line advanced, non-squamous NSCLC. Results: In 2/3L NSCLC, the signature was associated with improvement in survival on linifanib monotherapy (HR=0.51 vs. signature negative; P=0.0017), but no improvement in survival on other treatments (P=0.87). In the first-line setting with CP, the signature was associated with significant PFS improvement with linifanib and a trend towards significant overall survival improvement at high dose (Table). Conclusions: A baseline plasma biomarker signature is associated with improved survival in advanced NSCLC patients on linifanib. Incorporation of this signature should be considered in any further investigation of linifanib in NSCLC. [Table: see text]

An open-label, phase 1 study evaluating safety, tolerability, and pharmacokinetics of linifanib (ABT-869) in Japanese patients with solid tumors

Purpose

This phase 1 study assessed the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of linifanib in Japanese patients with advanced solid tumors.

Methods

Patients were assigned to one of four sequential cohorts (0.05, 0.10, 0.20, or 0.25 mg/kg) of oral, once-daily linifanib on a 21-day cycle. Adverse events (AEs) were assessed per common terminology criteria for adverse events v3.0; tumor responses were assessed by response evaluation criteria in solid tumors.

Results

Eighteen patients were enrolled. Eleven (61%) received ≥3 prior therapies. Dose-limiting toxicities were Grade 3 ALT increase (0.10 mg/kg linifanib) and Grade 1 T-wave inversion (0.25 mg/kg linifanib) requiring dose interruption for >7 days and discontinuation on day 29. The most common linifanib-related AE was hypertension. Other significant treatment-related AEs included proteinuria, fatigue, and palmar-plantar erythrodysaesthesia. Linifanib pharmacokinetics were dose-proportional across 0.10–0.25 mg/kg. Two patients (11.1%) had confirmed partial responses, 12 had a best response of stable disease (11 had stable disease for ≥12 weeks), and four patients were not evaluable due to incomplete data. Four patients (lung cancer, breast cancer, thymic cancer, sarcoma) have continued linifanib for ≥48 weeks (range, 48–96+ weeks).

Conclusion

Linifanib was well tolerated with promising preliminary clinical activity in Japanese patients. Later-phase global studies examining linifanib efficacy will include Japanese patients.

Enzyme replacement therapy prevents dental defects in a model of hypophosphatasia

Hypophosphatasia (HPP) occurs from loss-of-function mutation in the tissue-non-specific alkaline phosphatase (TNALP) gene, resulting in extracellular pyrophosphate accumulation that inhibits skeletal and dental mineralization. TNALP-null mice (Akp2(-/-)) phenocopy human infantile hypophosphatasia; they develop rickets at 1 week of age, and die before being weaned, having severe skeletal and dental hypomineralization and episodes of apnea and vitamin B(6)-responsive seizures. Delay and defects in dentin mineralization, together with a deficiency in acellular cementum, are characteristic. We report the prevention of these dental abnormalities in Akp2(-/-) mice receiving treatment from birth with daily injections of a mineral-targeting, human TNALP (sALP-FcD(10)). sALP-FcD(10) prevented hypomineralization of alveolar bone, dentin, and cementum as assessed by micro-computed tomography and histology. Osteopontin--a marker of acellular cementum--was immuno-localized along root surfaces, confirming that acellular cementum, typically missing or reduced in Akp2(-/-) mice, formed normally. Our findings provide insight concerning how acellular cementum is formed on tooth surfaces to effect periodontal ligament attachment to retain teeth in their osseous alveolar sockets. Furthermore, they provide evidence that this enzyme-replacement therapy, applied early in post-natal life--where the majority of tooth root development occurs, including acellular cementum formation--could prevent the accelerated tooth loss seen in individuals with HPP.

Melanoma-associated antigen expression in lymphangioleiomyomatosis renders tumor cells susceptible to cytotoxic T cells

The antibody HMB45 is used to diagnose lymphangioleiomyomatosis, a hyperproliferative disorder of lung smooth muscle cells with mutations in both alleles of either TSC1 or TSC2. A subset of these tumor cells expresses the melanoma-associated antigens gp100 and melanoma antigen recognized by T cells (MART-1). To explore the feasibility of targeting tumors in lymphangioleiomyomatosis by melanoma immunotherapy, we therefore assessed melanoma target antigen expression and existing immune infiltration of affected tissue compared with normal lung and melanoma as well as the susceptibility of cultured lymphangioleiomyomatosis cells to melanoma reactive cytotoxic T lymphocytes in vitro. Tumors expressed tyrosinase-related proteins 1 and 2 but not tyrosinase, in addition to gp100 and MART-1, and were densely infiltrated by macrophages, but not dendritic cells or T cell subsets. Although CD8(+) lymphocytes were sparse compared with melanoma, cells cultured from lymphangioleiomyomatosis tissue were susceptible to cytotoxic, gp100 reactive, and major histocompatibility complex class I restricted CD8(+) T cells in functional assays. Responder T cells selectively clustered and secreted interferon-gamma in response to HLA-matched melanocytes and cultured lymphangioleiomyomatosis cells. This reactivity exceeded that based on detectable gp100 expression; thus, tumor cells in lymphangioleiomyomatosis may process melanosomal antigens different from melanocytic cells. Therefore, boosting immune responses to gp100 in lymphangioleiomyomatosis may offer a highly desirable treatment option for this condition.