Anti-tissue factor antibody conjugated with monomethyl auristatin E or deruxtecan in pancreatic cancer models.

Antibody-drug conjugates (ADCs) have been recognized as a promising class of cancer therapeutics. Tissue factor (TF), an initiator of the blood coagulation pathway, has been investigated regarding its relationship with cancer, and several preclinical and clinical studies have presented data on anti-TF ADCs, including tisotumab vedotin, which was approved in 2021. However, the feasibility of other payloads in the design of anti-TF ADCs is still unclear because no reports have compared payloads with different cytotoxic mechanisms. For ADCs targeting other antigens, such as Her2, optimizing the payload is also an important issue in order to improve in vivo efficacy. In this study, we prepared humanized anti-TF Ab (clone.1084) conjugated with monomethyl auristatin E (MMAE) or deruxtecan (DXd), and evaluated the efficacy in several cell line- and patient-derived xenograft models of pancreatic cancer. As a result, optimizing the drug / Ab ratio was necessary for each payload in order to prevent pharmacokinetic deterioration and maximize delivery efficiency. In addition, MMAE-conjugated anti-TF ADC showed higher antitumor effects in tumors with strong and homogeneous TF expression, while DXd-conjugated anti-TF ADC was more effective in tumors with weak and heterogeneous TF expression. Analysis of a pancreatic cancer tissue array showed weak and heterogeneous TF expression in most TF-positive specimens, indicating that the response rate to pancreatic cancer might be higher for DXd- than MMAE-conjugated anti-TF ADC. Nevertheless, our findings indicated that optimizing the ADC payloads individually in each patient could maximize the potential of ADC therapeutics.

Tumor Targeting of 211At-Labeled Antibody under Sodium Ascorbate Protection against Radiolysis.

Astatine-211 (211At) is an alpha emitter applicable to radioimmunotherapy (RIT), a cancer treatment that utilizes radioactive antibodies to target tumors. In the preparation of 211At-labeled monoclonal antibodies (211At-mAbs), the possibility of radionuclide-induced antibody denaturation (radiolysis) is of concern. Our previous study showed that this 211At-induced radiochemical reaction disrupts the cellular binding activity of an astatinated mAb, resulting in attenuation of in vivo antitumor effects, whereas sodium ascorbate (SA), a free radical scavenger, prevents antibody denaturation, contributing to the maintenance of binding and antitumor activity. However, the influence of antibody denaturation on the pharmacokinetics of 211At-mAbs relating to tumor accumulation, blood circulation time, and distribution to normal organs remains unclear. In this study, we use a radioactive anti-human epidermal growth factor receptor 2 (anti-HER2) mAb to demonstrate that an 211At-induced radiochemical reaction disrupts active targeting via an antigen-antibody interaction, whereas SA helps to maintain targeting. In contrast, there was no difference in blood circulation time as well as distribution to normal organs between the stabilized and denatured immunoconjugates, indicating that antibody denaturation may not affect tumor accumulation via passive targeting based on the enhanced permeability and retention effect. In a high-HER2-expressing xenograft model treated with 1 MBq of 211At-anti-HER2 mAbs, SA-dependent maintenance of active targeting contributed to a significantly better response. In treatment with 0.5 or 0.2 MBq, the stabilized radioactive mAb significantly reduced tumor growth compared to the denatured immunoconjugate. Additionally, through a comparison between a stabilized 211At-anti-HER2 mAb and radioactive nontargeted control mAb, we demonstrate that active targeting significantly enhances tumor accumulation of radioactivity and in vivo antitumor effect. In RIT with 211At, active targeting contributes to efficient tumor accumulation of radioactivity, resulting in a potent antitumor effect. SA-dependent protection that successfully maintains tumor targeting will facilitate the clinical application of alpha-RIT.

Radioimmunotherapy with an 211 At-labeled anti-tissue factor antibody protected by sodium ascorbate.

Tissue factor (TF), the trigger protein of the extrinsic blood coagulation cascade, is abundantly expressed in various cancers including gastric cancer. Anti-TF monoclonal antibodies (mAbs) capable of targeting cancers have been successfully applied to armed antibodies such as antibody-drug conjugates (ADCs) and molecular imaging probes. We prepared an anti-TF mAb, clone 1084, labeled with astatine-211 (211 At), as a promising alpha emitter for cancer treatment. Alpha particles are characterized by high linear energy transfer and a range of 50-100 µm in tissue. Therefore, selective and efficient tumor accumulation of alpha emitters results in potent antitumor activities against cancer cells with minor effects on normal cells adjacent to the tumor. Although the 211 At-conjugated clone 1084 (211 At-anti-TF mAb) was disrupted by an 211 At-induced radiochemical reaction, we demonstrated that astatinated anti-TF mAbs eluted in 0.6% or 1.2% sodium ascorbate (SA) solution were protected from antibody denaturation, which contributed to the maintenance of cellular binding activities and cytocidal effects of this immunoconjugate. Although body weight loss was observed in mice administered a 1.2% SA solution, the loss was transient and the radioprotectant seemed to be tolerable in vivo. In a high TF-expressing gastric cancer xenograft model, 211 At-anti-TF mAb in 1.2% SA exerted a significantly greater antitumor effect than nonprotected 211 At-anti-TF mAb. Moreover, the antitumor activities of the protected immunoconjugate in gastric cancer xenograft models were dependent on the level of TF in cancer cells. These findings suggest the clinical availability of the radioprotectant and applicability of clone 1084 to 211 At-radioimmunotherapy.

Toxicological implication of prostaglandin transporter SLCO2A1 inhibition by cigarette smoke in exacerbation of lung inflammation.

We reported that bleomycin (BLM)-induced pulmonary fibrosis was exacerbated in the prostaglandin transporter gene (Slco2a1)-deficient mice (Slco2a1(-/-)). Because cigarette smoke (CS) contributes to creating a profibrotic milieu in the respiratory region, the present study aimed to investigate the impact of CS on SLCO2A1-associated pathogenesis in the lungs of BLM-instilled mice. Bronchoalveolar lavage (BAL) fluid cell analysis indicated more severe inflammation in Slco2a1(-/-) on day 5 after BLM intratracheal instillation, and Slco2a1 deletion increased mRNA expression of pro-inflammatory cytokines (Tnf-α and Il-1ß) and chemokine (Ccl5) in BAL cells. Male Slco2a1(-/-) exhibited significantly higher amounts of released Il-1ß in BAL fluid, compared with female Slco2a1(-/-), male or female Slco2a1(+/+) group. The amount of PGE2 collected in BAL fluid tended to increase in Slco2a1(-/-) compared with Slco2a1(+/+) group, whereas the PGE2 concentrations in lung tissues were comparable between both groups. Besides, PGE2 accumulated more in BAL fluid of male than that of female mice. Therefore, Slco2a1-deficient male mice were found to be more susceptible to BLM-treatment. Moreover, CS extracts (CSE) significantly reduced initial PGE2 uptake by rat type1 alveolar epithelial cell-like (AT1-L) cells and human SLCO2A1-transfected cells. Exposure of AT1-L cells to CSE resulted in decreased mRNA expression of Slco2a1, suggesting that CS modulates SLCO2A1 function. These results indicate that exacerbated lung inflammation is attributed to an increase in Il-1ß peptide and PGE2 accumulation in the alveolar space, which exhibits a male predominance. SLCO2A1 inhibition by CSE is considered to be a new rationale for the lung toxicity of CS.

Evaluation of the antitumor mechanism of antibody-drug conjugates against tissue factor in stroma-rich allograft models.

Tissue factor (TF) is known to be overexpressed in various cancers including pancreatic cancer. The upregulation of TF expression has been observed not only in tumor cells, but also in tumor stromal cells. Because of the potential of TF as a delivery target, several studies investigated the effectiveness of Ab-drug conjugates (ADCs) against TF for cancer therapy. However, it is still unclear whether anti-TF ADC can exert toxicity against both tumor cells and tumor stromal cells. Here, we prepared ADC using a rat anti-mouse TF mAb (clone.1157) and 2 types of in vivo murine pancreatic cancer models, one s.c. and other orthotopic with an abundant tumor stroma. We also compared the feasibility of bis-alkylating conjugation (bisAlk) with that of conventional maleimide-based conjugation (MC). In the s.c. models, anti-TF ADC showed greater antitumor effects than control ADC. The results also indicated that the bisAlk linker might be more suitable than the MC linker for cancer treatments. In the orthotopic model, anti-TF ADC showed greater in vivo efficacy and more extended survival time control ADC. Treatment with anti-TF ADC (20 mg/kg, three times a week) did not affect mouse body weight changes in any in vivo experiment. Furthermore, immunofluorescence staining indicated that anti-TF ADC delivered agents not only to TF-positive tumor cells, but also to TF-positive tumor vascular endothelial cells and other tumor stromal cells. We conclude that anti-TF ADC should be a selective and potent drug for pancreatic cancer therapy.

Experimental Evidence for Resecretion of PGE2 across Rat Alveolar Epithelium by OATP2A1/SLCO2A1-Mediated Transcellular Transport.

Prostaglandin transporter Oatp2a1/Slco2a1 is expressed at the apical (AP) membranes of type-1 alveolar epithelial (AT1) cells. To investigate the role of OATP2A1 in prostaglandin E2 (PGE2) handling by alveolar epithelium, we studied PGE2 transport across and secretion from monolayers of rat AT1-like (AT1-L) cells obtained by trans-differentiation of type-2 alveolar epithelial cells isolated from male Wistar rats. Rat AT1-L cells expressed Oatp2a1/Slco2a1, together with smaller amounts of Mrp4/Abcc4 and Oct1/Slc22a1 PGE2 uptake was saturable with Km 43.9 ± 21.9 nM. Transcellular transport of PGE2 across AT1-L cells grown on permeable filters in the AP-to-basolateral (BL) direction was 5-fold greater than that in the reverse direction and was saturable with Km 118 ± 26.8 nM; it was significantly inhibited by OATP inhibitors bromosulfophthalein (BSP) and suramin, and an MRP4 inhibitor, Ceefourin 1. We simultaneously monitored the effects of BSP on the distribution of PGE2 produced by bradykinin-treated AT1-L cells and PGE2-d4 externally added on the AP side of the cells. In the presence of BSP, PGE2 increased more rapidly on the AP side, whereas PGE2-d4 decreased more slowly on the AP side. The decrease in PGE2-d4 from the AP side corresponded well to the increase on the BL side, indicating that intracellular metabolism did not occur. These results suggest that Oatp2a1 and Mrp4 mediate transepithelial transport of PGE2 in the AP-to-BL direction. Therefore, OATP2A1 may be an important regulator of PGE2 in alveolar epithelium by reducing secretion of PGE2 and facilitating "resecretion" of PGE2 present in the alveolar lumen to the interstitial space or blood.

Utility of epirubicin-incorporating micelles tagged with anti-tissue factor antibody clone with no anticoagulant effect.

Tissue factor (TF), an initiator of the extrinsic blood coagulation cascade, is overexpressed in different types of cancer. Tissue factor overexpression is also known as a poor prognostic factor in pancreatic cancer. We recently developed anti-TF antibody (clone1849)-conjugated epirubicin-incorporating micelles (NC-6300), and reported that this anti-TF1849-NC-6300 showed enhanced antitumor activity against TF-high expressed human pancreatic cancer cells, when compared with NC-6300 alone. However, clone 1849 antibody inhibited TF-associated blood coagulation activity. We studied another anti-TF antibody, clone 1859, which had no effect on blood coagulation and prepared anti-TF1859-NC-6300. In addition, to determine the optimum size of the antibody fragment to conjugate with NC-6300, three forms of the 1859 antibody (whole IgG, F[ab']2 , and Fab') were conjugated to NC-6300. The antitumor effect of each anti-TF1859-NC-6300 was studied in vitro and in vivo, using two human pancreatic cancer cell lines, BxPC3 with high-expressed TF, and SUIT2 with low levels of TF. In vitro, all forms of anti-TF1859-NC-6300 showed higher cytocidal effects than NC-6300 in BxPC3, whereas this enhanced effect was not observed in SUIT2. Likewise, all forms of anti-TF1859-NC-6300 significantly suppressed tumor growth when compared to NC-6300 in the BxPC3, but not in the SUIT2, xenograft model. Among the three forms of conjugates, anti-TF1859-IgG-NC-6300 had a higher antitumor tendency in TF-high expressed cells. Thus, we have confirmed an enhanced antitumor effect of anti-TF1859-NC-6300 in a TF-high expressing tumor; anti-TF1859-IgG-NC-6300 could be used to simplify the manufacturing process of the antibody-micelle conjugation for future clinical studies.

Comparison of Treatment Outcomes of Different Immobilized Finger Positions After Repair of Flexor Tendon Rupture in Zones I and II: A Nonrandomized Controlled Trial With Historical Control Group.

Introduction The position of finger immobilization after flexor tendon rupture repair is changed to the extended position to prevent flexion contracture of the interphalangeal (IP) joint. However, in Strickland's assessment, We believe that a reduction in TAF (total active flexion) affects the outcome and that extension fixation is not necessarily the primary focus. For example, there are management methods that swap the fixed position between day and night. It is assumed that some effect is sought by placing the fingers in the flexed position. That is, the method of fixation is currently selected at individual facilities through twists and turns; however, the indications and criteria for selecting finger fixation positions are ambiguous, and they are apparently subject to the experience of therapists. This study aimed to characterize follow-up outcomes of flexion and extension fixation after zones I and II flexor tendon rupture repair. Methods This nonrandomized controlled trial with historical controls included 25 patients with flexor tendon ruptures of 30 fingers. The flexion fixation group consisted of 12 patients (n=16 fingers) and the extension fixation group consisted of 13 patients (n=14 fingers). The group with flexion fixation comprised patients who slept with their injured fingers in the flexed position (intervention group). The group with extension was retrospectively selected between April 2017 and March 2019, who slept with their injured finger in the extended position (historical control group). Strickland assessments of the range of motion (ROM) of each joint at the conclusion of hand therapy, the ratio of total active motion of the repaired, to the healthy finger (%TAF), and IP joint extension limitation angles were compared using Mann-Whitney U tests. Ratios of excellent and good ratings based on the Strickland assessment were compared using Fisher exact tests. Result The results of the Strickland assessment showed excellent or good outcomes for 22 (73%) of 30 fingers, which was in line with our previous findings. Strickland ratings of excellent were achieved in seven (44%) of 16 fingers and four (28%) of 14 fingers in the groups with flexion and extension fixation, respectively. The outcomes for two (22%) of 16 fingers and seven (78%) of 14 fingers in the groups with flexion and extension fixation were, respectively, rated as good. The proportion of patients rated as excellent was significantly higher in the group with flexion than extension fixation (p=0.040). The %TAF and the active flexion angle of the distal interphalangeal (DIP) joint were higher in the group with flexion than extension fixation (p=0008 and p=0.025, respectively). Furthermore, the total angle of the IP joint limit of extension did not significantly differ between the groups. Conclusion Flexion fixation after flexor tendon rupture achieved an excellent Strickland rating and was more effective than extension fixation, especially in terms of the active flexion ROM of the DIP joint. Flexion fixation might be an alternative to extension fixation because the range of flexion should be greater and might provide a range of finger extension motion equivalent to that of extension fixation.

Subtracted 3D CT angiography for the evaluation of intracranial aneurysms in 256-slice multidetector CT: usefulness of the 80-kVp plus compact contrast medium bolus protocol.

OBJECTIVES: To evaluate the usefulness of an 80-kVp and compact contrast material protocol for arterial phase subtracted cerebral 3D-CTA using 256-slice multidetector CT. METHODS: Thirty-two patients underwent CT with 100 kVp and received a contrast dose of 370 mgI/kg body weight over 15 s (protocol A). Thirty-three patients underwent CT with 100 kVp and received a contrast dose of 296 mgI/kg body weight over 10 s (protocol B). Thirty-three other patients underwent CT with 80 kVp and received a contrast medium dose of 296 mgI/kg body weight over 10 s (protocol C). We compared the arterial attenuation and contrast noise ratio (CNR) of each protocol. Two independent readers assessed overall image quality. RESULTS: Arterial attenuation was significantly higher under protocols A (418.6 ± 71.1 HU) and C (442.7 ± 79.3 HU) than under protocol B (355.8 ± 107.2 HU; P < 0.05). The CNR of protocol C (26.1 ± 6.1) was higher than that of protocol A (20.7 ± 8.4; P < 0.05). The overall image quality of protocol A was higher than that of protocol C (P < 0.01). CONCLUSION: The 80-kVp plus compact contrast protocol is well suited to arterial phase subtracted cerebral 3D-CTA without confounding venous enhancement. KEY POINTS: • Subtracted 3D CT angiography is useful in the evaluation of intracranial aneurysms. • A compact contrast material protocol increased arterial attenuation without venous contamination. • Low-kVp CT compensated for the decreased amount of contrast medium. • An 80-kVp CT with a compact enhancement bolus provides good intracranial 3D-CT angiography.

Special Issue: Evaluation of the Antitumor Mechanism of Armed Antibodies.

This Special Issue focuses on the use of therapeutic antibodies in vitro, in vivo, and in clinical studies [...].

Chromatographic Analysis of the N-Glycan Profile on Therapeutic Antibodies Using FcγRIIIa Affinity Column Chromatography.

N-Linked glycosylation on IgG has a profound impact on antibody functions. The relationship between the N-glycan structure and the binding affinity of FcγRIIIa, relating to antibody-dependent cell-mediated cytotoxicity (ADCC) activity, is important for the efficient development of a therapeutic antibody. Here, we report an influence of the N-glycan structure of IgGs, Fc fragments, and antibody-drug conjugates (ADCs) on FcγRIIIa affinity column chromatography. We compared the retention time of several IgGs with heterogeneous and homogeneous N-glycans. IgGs with a heterogeneous N-glycan structure provided several peaks in column chromatography. On the other hand, homogeneous IgGs and ADCs gave a single peak in column chromatography. The length of glycan on IgG also affected the retention time of the FcγRIIIa column, suggesting that the length of glycan is also impacted by binding affinity to FcγRIIIa, resulting in ADCC activity. This analytic methodology provides evaluation of the binding affinity of FcγRIIIa and ADCC activity, not only full-length IgG but also Fc fragments, which are difficult to measure in a cell-based assay. Furthermore, we showed that the glycan-remodeling strategy controls the ADCC activity of IgGs, Fc fragment, and ADCs.

Identification of CD73 as the Antigen of an Antigen-Unknown Monoclonal Antibody Established by Exosome Immunization, and Its Antibody-Drug Conjugate Exerts an Antitumor Effect on Glioblastoma Cell Lines.

Development of antibodies against the native structure of membrane proteins with multiple transmembrane domains is challenging because it is difficult to prepare antigens with native structures. Previously, we successfully developed a monoclonal antibody against multi-pass membrane protein TMEM180 by exosome immunization in rats. This approach yielded antibodies that recognized cancer-specific antigens on the exosome. In this study, we performed immunoprecipitation using magnetic beads to identify the antigen of one of the rat antibody clones, 0614, as CD73. We then converted antibody 0614 to human chimeric antibody 0614-5. Glioblastoma (GB) was the cancer type with the highest expression of CD73 in the tumor relative to healthy tissue. An antibody-drug conjugate (ADC) of 0614-5 exerted an antitumor effect on GB cell lines according to expression of CD73. The 0614-5-ADC has potential to be used to treat cancers with high CD73 expression. In addition, our strategy could be used to determine the antigen of any antibody produced by exosome immunization, which may allow the antibody to advance to new antibody therapies.

Protection from contamination by 211At, an enigmatic but promising alpha-particle-emitting radionuclide.

PURPOSE: 211At, a promising alpha-particle-emitting radionuclide, can easily volatilize and contaminate the environment. To safely manage this unique alpha-particle-emitting radionuclide, we investigated the permeability of four types of plastic films and two types of rubber gloves against 211At and identified suitable materials that prevent contamination by 211At. METHODS: Four types of plastic films, polyethylene, polyvinylidene chloride, polyvinyl chloride, and a laminated film, and two types of rubber gloves, latex and nitrile, were examined. Small pieces of filter paper were covered with these materials, and a drop containing 100 kBq of 211At was placed on them. The radioactivity of the pieces of filter paper under the materials was evaluated by measuring counts using a gamma counter and obtaining autoradiograms 3.5 h later. These experiments were also performed using 225Ac, 125I, 111In, 201Tl, and 99mTc. RESULTS: 211At solution easily penetrated polyethylene, polyvinyl chloride, and latex rubber. Similar results were obtained for 125I, while other radionuclides did not penetrate films or gloves. These results suggest that halogenic radionuclides under anionic conditions are likely to penetrate plastic films and rubber gloves. CONCLUSION: Our evaluation revealed that, when 211At solution is used, the protection by polyvinylidene chloride, a laminated film, or nitrile rubber would be more effective than that by polyethylene, polyvinyl chloride, or latex rubber.

Antitumor effect of humanized anti­tissue factor antibody­drug conjugate in a model of peritoneal disseminated pancreatic cancer.

Tissue factor (TF) is an attractive target for cancer therapy due to its overexpression in multiple types of malignancies. In addition, TF has been reported to play functional roles in both cancer development and metastasis. Several groups have already developed antibody­drug conjugates (ADCs) against TF for use as cancer treatments, and have demonstrated their efficacies in conventional subcutaneous xenograft models and patient­derived xenograft models. However, no previous studies have investigated the effectiveness of anti­TF ADC in an advanced­stage cancer model. The present study developed an original humanized anti­TF monoclonal antibody conjugated with monomethyl auristatin E, and evaluated its in vivo efficacy in a pancreatic cancer xenograft model with peritoneal dissemination. In vitro assays demonstrated that the anti­TF ADC had potent binding affinity and cytotoxic activity against human pancreatic cancer cells that strongly expressed TF antigens. The anti­TF ADC also exhibited greater antitumor effect than that of a control ADC in conventional subcutaneous xenograft models, with efficacy depending on the TF expression in the tumor tissues. Furthermore, the anti­TF ADC significantly inhibited tumor growth in an orthotopic xenograft model, and extended the survival period in a murine peritoneal dissemination model. These results indicated that anti­TF ADC has the potential to be an effective treatment not only for primary tumors, but also for those that are widely disseminated. Therefore, it can be concluded that ADC targeting TF may be a promising agent for advanced pancreatic cancer therapy.

Stabilization of an 211At-Labeled Antibody with Sodium Ascorbate.

211At, an α-particle emitter, has recently attracted attention for radioimmunotherapy of intractable cancers. However, our sodium dodecyl sulfate polyacrylamide gel electrophoresis and flow cytometry analyses revealed that 211At-labeled immunoconjugates are easily disrupted. Luminol assay revealed that reactive oxygen species generated from radiolysis of water caused the disruption of 211At-labeled immunoconjugates. To retain their functions, we explored methods to protect 211At-immunoconjugates from oxidation and enhance their stability. Among several other reducing agents, sodium ascorbate most safely and successfully protected 211At-labeled trastuzumab from oxidative stress and retained the stability of the 211At-labeled antibody and its cytotoxicity against antigen-expressing cells for several days.

Reinforcement of antitumor effect of micelles containing anticancer drugs by binding of an anti-tissue factor antibody without direct cytocidal effects.

It has been preclinically and clinically proven that anticancer agent-incorporating (ACA-incorporating) polymeric micelles selectively accumulate in tumor via the enhanced permeability and retention (EPR) effect, yielding a wider therapeutic window and greater safety than conventional low-molecular weight ACAs. To increase the antitumor effect of these safer micelle formulations, epirubicin-incorporating polymer micelles (NC-6300) conjugated with monoclonal antibodies (mAbs) have been prepared. In this study, we used two types of mAb: an anti-tissue factor (TF) mAb that does not exert a direct cytocidal effect, and an anti-HER2 mAb that has a direct cytocidal effect. We compared the antitumor effects and pharmacological properties of the two types of antibody conjugated to NC-6300. Immunomicelles conjugated to anti-TF mAb exerted greater antitumor activity toward TF-positive stomach cancer than the combination of anti-TF mAb and NC-6300, and were distributed more uniformly throughout TF-positive tumor tissue than NC-6300. On the other hand, immunomicelles conjugated to anti-HER2 mAb did not exert significant antitumor activity toward HER2-positive stomach cancer relative to the combined use of anti-HER2 mAb and NC-6300. Thus, this immunomicelle-based strategy may be useful for antibodies that target cancer as pilot molecules even when the antibodies themselves do not have an antitumor effect.

Anti­tissue factor antibody­mediated immuno­SPECT imaging of tissue factor expression in mouse models of pancreatic cancer.

Tissue factor (TF) has emerged as a critical factor in oncogenic events, leading to the development of TF­targeted diagnostic and therapeutic approaches. A non­invasive imaging method to evaluate target molecule expression with high sensitivity and high quantitative ability is imperative for selecting the appropriate patients for TF­targeted therapy. To elucidate the potential of 111In­labeled anti­TF antibody 1849 (111In­1849) as an immuno­single photon emission computed tomography (SPECT) probe targeting TF, we evaluated TF­dependent in vitro binding as well as in vivo biodistribution and tumor accumulation of 111In­1849 in pancreatic cancer cells/models with varying TF expression levels. TF expression levels in five human pancreatic cancer cell lines, BxPC­3, BxPC­3­TF­knockout (BxPC­3­TFKO), Capan­1, PSN­1 and SUIT­2, were examined by immunofluorescence. Binding of 111In­1849 to each cell line was assessed. Biodistribution and imaging studies were also conducted in tumor­bearing mice. Furthermore, the relationship of TF expression with cell binding and tumor uptake was analyzed. In the immunofluorescence studies, BxPC­3 exhibited the highest TF expression, followed by Capan­1, PSN­1, SUIT­2 and BxPC­3­TFKO. Cell binding assays revealed that BxPC­3 cells had the highest 111In­1849 binding, followed by PSN­1, Capan­1 and SUIT­2; no binding was detected in BxPC­3­TFKO cells. The BxPC­3 xenograft was clearly visualized on 111In­1849 SPECT/CT, and the highest uptake was detected on day 4. The biodistribution of 111In­1849 on day 4 revealed that tumor uptake ranged from 8.68 to 50.58% of the injected dose per gram of tissue; BxPC­3 had the highest uptake and SUIT­2 had the lowest. TF expression was significantly associated with cell binding (R2=0.79, P<0.05) and tumor uptake (R2=0.92, P<0.01). The association of 111In­1849 uptake with TF expression suggests the potential application of non­invasive imaging with radiolabelled 1849 for selecting the appropriate patients who would likely respond to TF­targeted therapies in clinical practice.

Preparation and applications of a variety of fluoroalkyl end-capped oligomer/hydroxyapatite composites.

A variety of fluoroalkyl end-capped oligomers were applied to the preparation of fluorinated oligomer/hydroxyapatite (HAp) composites (particle size: 38-356 nm), which exhibit a good dispersibility in water and traditional organic solvents. These fluoroalkyl end-capped oligomer/HAp composites were easily prepared by the reactions of disodium hydrogen phosphate and calcium chloride in the presence of self-assembled molecular aggregates formed by fluoroalkyl end-capped oligomers in aqueous solutions. In these fluorinated HAp composites thus obtained, fluoroalkyl end-capped acrylic acid oligomers and 2-methacryloyloxyethanesulfonic acid oligomer/HAp nanocomposites afforded transparent colorless solutions toward water; however, fluoroalkyl end-capped N,N-dimethylacrylamide oligomer and acryloylmorpholine oligomer were found to afford transparent colorless solutions with trace amounts of white-colored HAp precipitants under similar conditions. HAp could be encapsulated more effectively into fluorinated 2-methacryloyloxyethanesulfonic acid oligomeric aggregate cores to afford colloidal stable fluorinated oligomer/HAp composites, compared to that of fluorinated acrylic acid oligomers. These fluorinated oligomer/HAp composites were applied to the surface modification of glass and PVA to exhibit a good oleophobicity imparted by fluorine. HAp formation was newly observed on the modified polyethylene terephthalate film surface treated with fluorinated 2-methacryloyloxyethanesulfonic acid oligomers and acrylic acid oligomer/HAp composites by soaking these films into the simulated body fluid.

Influence of the dissociation rate constant on the intra-tumor distribution of antibody-drug conjugate against tissue factor.

Antibody-drug conjugates (ADCs) are currently considered to be promising agents for cancer therapy. However, especially in solid tumors, the uneven distribution of ADCs would decrease their efficacy in clinical studies. We suggest that in addition to optimizing ADC components, such as the linker structure and anticancer agent, it is necessary to consider the distribution of the ADC within tumor tissue. In this study, we established three kinds of anti-tissue factor (TF) ADCs: 1849ADC with a low kd, 444ADC with an intermediate kd, and 1084ADC with a high kd. All three of the anti-TF ADCs exhibited almost the same in vitro cytotoxicity and pharmacological and biochemical characteristics, although the binding kinetics parameters differed. In vivo, all ADCs exerted equivalent antitumor effects against small BxPC3 tumors. However, on larger BxPC3 tumors, 1084ADC (higher kd) exerted higher antitumor activity than 1849ADC (lower kd). Furthermore, immunofluorescence staining indicated that 1084ADC was distributed throughout the whole tumor, whereas 1849ADC was mainly localized close to tumor vessels. We conclude that the ADC with a higher kd increased the antitumor effect of because it penetrated and distributed evenly throughout the entire solid tumor. These findings highlight the importance of the kd of a mAb in ADC design.

Near-infrared photoimmunotherapy of pancreatic cancer using an indocyanine green-labeled anti-tissue factor antibody.

AIM: To investigate near-infrared photoimmunotherapeutic effect mediated by an anti-tissue factor (TF) antibody conjugated to indocyanine green (ICG) in a pancreatic cancer model. METHODS: Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that utilizes an antibody-photosensitizer conjugate administration, followed by NIR light exposure. Anti-TF antibody 1849-ICG conjugate was synthesized by labeling of rat IgG2b anti-TF monoclonal antibody 1849 (anti-TF 1849) to a NIR photosensitizer, ICG. The expression levels of TF in two human pancreatic cancer cell lines were examined by western blotting. Specific binding of the 1849-ICG to TF-expressing BxPC-3 cells was examined by fluorescence microscopy. NIR-PIT-induced cell death was determined by cell viability imaging assay. In vivo longitudinal fluorescence imaging was used to explore the accumulation of 1849-ICG conjugate in xenograft tumors. To examine the effect of NIR-PIT, tumor-bearing mice were separated into 5 groups: (1) 100 µg of 1849-ICG i.v. administration followed by NIR light exposure (50 J/cm2) on two consecutive days (Days 1 and 2); (2) NIR light exposure (50 J/cm2) only on two consecutive days (Days 1 and 2); (3) 100 µg of 1849-ICG i.v. administration; (4) 100 µg of unlabeled anti-TF 1849 i.v. administration; and (5) the untreated control. Semiweekly tumor volume measurements, accompanied with histological and immunohistochemical (IHC) analyses of tumors, were performed 3 d after the 2nd irradiation with NIR light to monitor the effect of treatments. RESULTS: High TF expression in BxPC-3 cells was observed via western blot analysis, concordant with the observed preferential binding with intracellular localization of 1849-ICG via fluorescence microscopy. NIR-PIT-induced cell death was observed by performing cell viability imaging assay. In contrast to the other test groups, tumor growth was significantly inhibited by NIR-PIT with a statistically significant difference in relative tumor volumes for 27 d after the treatment start date [2.83 ± 0.38 (NIR-PIT) vs 5.42 ± 1.61 (Untreated), vs 4.90 ± 0.87 (NIR), vs 4.28 ± 1.87 (1849-ICG), vs 4.35 ± 1.42 (anti-TF 1849), at Day 27, P < 0.05]. Tumors that received NIR-PIT showed evidence of necrotic cell death-associated features upon hematoxylin-eosin staining accompanied by a decrease in Ki-67-positive cells (a cell proliferation marker) by IHC examination. CONCLUSION: The TF-targeted NIR-PIT with the 1849-ICG conjugate can potentially open a new platform for treatment of TF-expressing pancreatic cancer.