Thulium oxide nanoparticles as radioenhancers for the treatment of metastatic cutaneous squamous cell carcinoma

Metastases from cutaneous squamous cell carcinoma (cSCC) occur in 2%-5% of cases. Surgery is the standard treatment, often combined with adjuvant radiotherapy. Concurrent carboplatin treatment with post-operative radiotherapy may be prescribed, although it has not shown benefit in recent clinical trials in high-risk cSCC patients. The novel high-Z nanoparticle thulium (III) oxide has been shown to enhance radiation dose delivery to brain tumors by specific uptake of these nanoparticles into the cancerous tissue. As the dose-enhancement capacity of thulium oxide nanoparticles following radiotherapy against metastatic cSCC cells is unknown, its efficacy as a radiosensitizer was evaluated, with and without carboplatin. Novel and validated human patient-derived cell lines of metastatic cSCC were used. The sensitivity of the cells to radiation was investigated using short-term proliferation assays as well as clonogenic survival as the radiobiological endpoint. Briefly, cells were irradiated with 125 kVp orthovoltage x-rays (0-6 Gy) with and without thulium oxide nanoparticles (99.9% trace metals basis; 50 µg ml^-1) or low dose carboplatin pre-sensitization. Cellular uptake of the nanoparticles was first confirmed by microscopy and found to have no impact on short-term cell survival for the cSCC cells, highlighting the biocompatibility of thulium oxide nanoparticles. Clonogenic cell survival assays confirmed radio-sensitization when exposed to thulium nanoparticles, with the cell sensitivity increasing by a factor of 1.24 (calculated at the 10% survival fraction) for the irradiated cSCC cells. The combination of carboplatin with thulium oxide nanoparticles with irradiation did not result in significant further reductions in survival compared to nanoparticles alone. This is the first study to provide in vitro data demonstrating the independent radiosensitization effect of high-Z nanoparticles against metastatic cSCC with or without carboplatin. Further preclinical investigations with radiotherapy plus high-Z nanoparticles for the management of metastatic cSCC are warranted.

The Urokinase Plasminogen Activation System in Rheumatoid Arthritis: Pathophysiological Roles and Prospective Therapeutic Targets

Rheumatoid Arthritis (RA) is a chronic and progressive inflammatory disease characterized in its early stages by synovial hyperplasia and inflammatory cell infiltration and later by irreversible joint tissue destruction. The Plasminogen Activation System (PAS) is associated with a wide range of physiological and pathophysiological states involving fibrinolysis, inflammation and tissue remodeling. Various components of the PAS are implicated in the pathophysiology of RA. Urokinase Plasminogen Activator (uPA) in particular is a pro-inflammatory mediator that appears to play an important role in the bone and cartilage destruction associated with RA. Clinical studies have shown that uPA and its receptor uPAR are overexpressed in synovia of patients with rheumatoid arthritis. Further, genetic knockdown and antibody-mediated neutralization of uPA have been shown to be protective against induction or progression of arthritis in animal models. The pro-arthritic role of uPA is differentiated from its haemodynamic counterpart, tissue plasminogen activator (tPA), which appears to play a protective role in RA animal models. This review summarises available evidence supporting the PAS as a critical determinant of RA pathogenesis and highlights opportunities for the development of novel uPAS-targeting therapeutics.

Illustrated State-of-the-Art Capsules of the ISTH 2020 Congress

The 2020 Congress of the International Society of Thrombosis and Haemostasis (ISTH) was held virtually July 12-15, 2019, due to the coronavirus disease 2019 pandemic. The congress convenes annually to discuss clinical and basic topics in hemostasis and thrombosis. Each year, the program includes State of Art (SOA) lectures given by prominent scientists. Presenters are asked to create Illustrated Capsules of their talks, which are concise illustrations with minimal explanatory text. Capsules cover major themes of the presentation, and these undergo formal peer review for inclusion in this article. Owing to the shift to a virtual congress this year, organizers reduced the program size. There were 39 SOA lectures virtually presented, and 29 capsules (9 from talks omitted from the virtual congress) were both submitted and successful in peer review, and are included in this article. Topics include the roles of the hemostatic system in inflammation, infection, immunity, and cancer, platelet function and signaling, platelet function disorders, megakaryocyte biology, hemophilia including gene therapy, phenotype tests in hemostasis, von Willebrand factor, anticoagulant factor V, computational driven discovery, endothelium, clinical and basic aspects of thrombotic microangiopathies, fibrinolysis and thrombolysis, antithrombotics in pediatrics, direct oral anticoagulant management, and thrombosis and hemostasis in pregnancy. Capsule authors invite virtual congress attendees to refer to these capsules during the live presentations and participate on Twitter in discussion. Research and Practice in Haemostasis and Thrombosis will release 2 tweets from @RPTHJournal during each presentation, using #IllustratedReview, #CoagCapsule and #ISTH2020. Readers are also welcome to utilize capsules for teaching and ongoing education.

Design, synthesis and evaluation of carbamate-linked uridyl-based inhibitors of human ST6Gal I

Sialic acid at the terminus of cell surface glycoconjugates is a critical element in cell-cell recognition, receptor binding and immune responses. Sialyltransferases (ST), the enzymes responsible for the biosynthesis of sialylated glycans are highly upregulated in cancer and the resulting hypersialylation of the tumour cell surface correlates strongly with tumour growth, metastasis and drug resistance. Inhibitors of human STs, in particular human ST6Gal I, are thus expected to be valuable chemical tools for the discovery of novel anticancer drugs. Herein, we report on the computationally-guided design and development of uridine-based inhibitors that replace the charged phosphodiester linker of known ST inhibitors with a neutral carbamate to improve pharmacokinetic properties and synthetic accessibility. A series of 24 carbamate-linked uridyl-based compounds were synthesised by coupling aryl and hetaryl α-hydroxyphosphonates with a 5'-amino-5'-deoxyuridine fragment. The inhibitory activities of the newly synthesised compounds against recombinant human ST6Gal I were determined using a luminescent microplate assay, and five promising inhibitors with K_i's ranging from 1 to 20 µM were identified. These results show that carbamate-linked uridyl-based compounds are a potential new class of readily accessible, non-cytotoxic ST inhibitors to be further explored.

6-Substituted amiloride derivatives as inhibitors of the urokinase-type plasminogen activator for use in metastatic disease

The oral K+-sparing diuretic amiloride shows anti-cancer side-activities in multiple rodent models. These effects appear to arise, at least in part, through moderate inhibition of the urokinase-type plasminogen activator (uPA, K_i = 2.4 µM), a pro-metastatic trypsin-like serine protease that is upregulated in many aggressive solid malignancies. In applying the selective optimization of side-activity (SOSA) approach, a focused library of twenty two 6-substituted amiloride derivatives were prepared, with multiple examples displaying uPA inhibitory potencies in the nM range. X-ray co-crystal structures revealed that the potency increases relative to amiloride arise from increased occupancy of uPA's S1β subsite by the appended 6-substituents. Leading compounds were shown to have high selectivity over related trypsin-like serine proteases and no diuretic or anti-kaliuretic effects in rats. Compound 15 showed anti-metastatic effects in a xenografted mouse model of late-stage lung metastasis.

Characterizing the role of tissue-type plasminogen activator in a mouse model of Group A streptococcal infection

Plasmin(ogen) acquisition is critical for invasive disease initiation by Streptococcus pyogenes (GAS). Host urokinase plasminogen activator (uPA) plays a role in mediating plasminogen activation for GAS dissemination, however the contribution of tissue-type plasminogen activator (tPA) to GAS virulence is unknown. Using novel tPA-deficient ALBPLG1 mice, our study revealed no difference in mouse survival, bacterial dissemination or the pathology of GAS infection in the absence of tPA in AlbPLG1/tPA-/- mice compared to AlbPLG1 mice. This study suggests that tPA has a limited role in this humanized model of GAS infection, further highlighting the importance of its counterpart uPA in GAS disease.

Paracrine recruitment and activation of fibroblasts by c-Myc expressing breast epithelial cells through the IGFs/IGF-1R axis

Fibroblasts are among the most abundant stromal cells in the tumor microenvironment (TME), progressively differentiating into activated, motile, myofibroblast-like, protumorigenic cells referred to as Cancer-Associated Fibroblasts (CAFs). To investigate the mechanisms by which epithelial cells direct this transition, the early stages of tumorigenesis were exemplified by indirect cocultures of WI-38 or human primary breast cancer fibroblasts with human mammary epithelial cells expressing an inducible c-Myc oncogene (MCF10A-MycER). After c-Myc activation, the conditioned medium (CM) of MCF10A-MycER cells significantly enhanced fibroblast activation and mobilization. As this was accompanied by decreased insulin-like growth factor binding protein-6 (IGFBP-6) and increased insulin-like growth factor-1 and IGF-II (IGF-I, IGF-II) in the CM, IGFs were investigated as key chemotactic factors. Silencing IGFBP-6 or IGF-I or IGF-II expression in epithelial cells or blocking Insulin-like growth factor 1 receptor (IGF-1R) activity on fibroblasts significantly altered fibroblast mobilization. Exposure of WI-38 fibroblasts to CM from induced MCF10A-MycER cells or to IGF-II upregulated FAK phosphorylation on Tyr³⁹⁷ , as well as the expression of α-smooth muscle actin (α-SMA), features associated with CAF phenotype and increased cell migratory/invasive behavior. In three-dimensional (3D)-organotypic assays, WI-38 or human primary fibroblasts, preactivated with either CM from MCF10A-MycER cells or IGFs, resulted in a permissive TME that enabled nontransformed MCF10A matrix invasion. This effect was abolished by inhibiting IGF-1R activity. Thus, breast epithelial cell oncogenic activation and stromal fibroblast transition to CAFs are linked through the IGFs/IGF-1R axis, which directly promotes TME remodeling and increases tumor invasion.

Is high-risk cutaneous squamous cell carcinoma of the head and neck a suitable candidate for current targeted therapies?

OBJECTIVE

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy, most frequently affecting the head and neck. Treatment often requires surgery and can have significant functional morbidity. Research into disease pathogenesis and second line medical management of cSCC is limited. We assess genetic mutations in high-risk, primary head and neck cutaneous squamous cell carcinomas (HNcSCC) that may hinder or be beneficial for use of targeted therapy in disease management.

METHODS

Genetic alterations and variant allele frequencies (VAFs) were analysed using a clinically relevant 48 gene panel in 10 primary high-risk non-metastatic treatment-naïve HNcSCC to evaluate applicability of targeted therapeutics. Variants present at all VAFs were evaluated for pathogenicity. Somatic mutation patterns of individual tumours were analysed.

RESULTS

High-risk HNcSCC showed a high proportion (82%) of C to T transitions in keeping with ultraviolet-mediated damage. There was significant intratumour genetic heterogeneity in this cohort (MATH scores 20-89) with the two patients <45 years of age showing highest intratumour heterogeneity. TP53 was altered at VAF >22% in all cases, and mutations with highest VAF were observed in tumour suppressor genes in 80%. 70% of cases demonstrated at least one mutation associated with treatment resistance (KIT S821F, KIT T670I, RAS mutations at codons 12 and 13).

CONCLUSION

We demonstrate high proportion tumour suppressor loss of function mutations, high intratumour genetic heterogeneity, and presence of well recognised resistance mutations in treatment naïve primary HNcSCC. These factors pose challenges for successful utilisation of targeted therapies.

Expression of cancer stem cell markers is prognostic in metastatic gastroesophageal adenocarcinoma

Gastroesophageal adenocarcinoma is a common and highly lethal malignancy. Cancer stem cells (CSCs) have a key role in the development and progression of metastatic disease. While expression of CSC markers CD44, CD133 and aldehyde dehydrogenase 1 (ALDH1) in locoregional gastroesophageal cancer is known to be associated with poorer clinical outcomes, the significance of CSC marker expression in distal metastatic disease is unknown. We investigated the clinicopathological and prognostic associations of the CSC markers, CD44, CD133, and ALDH1, on metastatic deposits from gastroesophageal adenocarcinomas, and evaluated the association of CSC expression with urokinase-type plasminogen activator receptor (uPAR) expression. Of the 36 patients included in the study, 16 (44%) were positive for CD44, 13 (36%) were positive for CD133, and 26 (72%) were positive for ALDH1. CD44 expression was significantly associated with poorer overall survival (OS) in univariate [hazard ratio (HR) 2.9, 95% confidence interval (CI) 1.3-6.9, p=0.008] and multivariate analyses (HR 2.5, 95%CI 1.1-6.2, p=0.04). ALDH1 expression was significantly associated with poorer OS in univariate (HR 2.4, 95% CI 1.01-5.7, p=0.04) analysis but was not significant in multivariate analysis. Both CD44 and ALDH1 expression were significantly associated with uPAR expression. We found no association between CD133 expression and OS. CD44 expression on metastatic disease from gastroesophageal adenocarcinomas is an independent prognostic marker associated with poorer OS. These results expand current evidence to support the role of CSCs as biomarkers in metastatic gastroesophageal cancer.

6-Substituted Hexamethylene Amiloride (HMA) Derivatives as Potent and Selective Inhibitors of the Human Urokinase Plasminogen Activator for Use in Cancer

Metastasis is the cause of death in the majority (∼90%) of malignant cancers. The oral potassium-sparing diuretic amiloride and its 5-substituted derivative 5 -N, N-(hexamethylene)amiloride (HMA) reportedly show robust antitumor/metastasis effects in multiple in vitro and animal models. These effects are likely due, at least in part, to inhibition of the urokinase plasminogen activator (uPA), a key protease determinant of cell invasiveness and metastasis. This study reports the discovery of 6-substituted HMA analogs that show nanomolar potency against uPA, high selectivity over related trypsin-like serine proteases, and minimal inhibitory effects against epithelial sodium channels (ENaC), the diuretic and antikaliuretic target of amiloride. Reductions in lung metastases were demonstrated for two analogs in a late-stage experimental mouse metastasis model, and one analog completely inhibited formation of liver metastases in an orthotopic xenograft mouse model of pancreatic cancer. The results support further evaluation of 6-substituted HMA derivatives as uPA-targeting anticancer drugs.

Safety and Efficacy of Oxaliplatin Doublet Adjuvant Chemotherapy in Elderly Patients With Stage III Colon Cancer

BACKGROUND

Colon cancer is common in the elderly, but owing to under representation in clinical trials, the benefit of standard therapies is uncertain in this age group. We aimed to clarify the efficacy and complications of adjuvant oxaliplatin and fluoropyrimidine chemotherapy for patients 70 years and older with stage III colon cancer.

PATIENTS AND METHODS

All patients with stage III colon adenocarcinoma were identified from an Australian cancer registry (2006-2013). Multivariable Cox hazard regression was used to determine prognostic factors for all-cause mortality. Chemotherapy complications were quantified using discontinuation rates, hospital admissions, and mortality for 12 months after starting chemotherapy.

RESULTS

A total of 2164 patients fulfilled our inclusion criteria, including 1080 (49.9%) patients ≥ 70 years. Patients ≥ 70 years were less likely to receive adjuvant chemotherapy (60.7% vs. 89.6%) or oxaliplatin doublet chemotherapy (18.8% vs. 71.2%). Older patients receiving oxaliplatin were more likely to cease treatment early (18.7% vs. 7.6%) and require hospital admission (67.0% vs. 53.5%). The addition of oxaliplatin provided an overall survival benefit for patients < 70 years (hazard ratio, 0.44; 95% confidence interval, 0.3-0.6; P < .0001) and for patients ≥ 70 years (hazard ratio, 0.64; 95% confidence interval, 0.5-0.9; P = .005).

CONCLUSIONS

Despite a modestly increased rate of hospital admission and early chemotherapy cessation, we demonstrate a persistent survival benefit for the addition of oxaliplatin to a fluoropyrimidine as adjuvant treatment for stage III colon cancer in elderly patients.

Probing the pharmacokinetics of cucurbit[7, 8 and 10]uril: and a dinuclear ruthenium antimicrobial complex encapsulated in cucurbit[10]uril

The relatively non-toxic family of cucurbit[n]uril, Q[n], have shown considerable potential in vitro as drug delivery agents, with only a few examples of pharmacokinetic (PK) studies for drug⊂Q[n]. Drug-free Q[n] PK studies are the next step in determining the pharmacological applicability in their drug delivery potential. The results for the first PK and bio-distribution of drug-free ¹⁴C-Q[7] are described for administration via intravenous (i.v.) and intraperitoneal (i.p.) dosing. A study of oral administration of drug-free ¹⁴C-Q[8] has also been undertaken to determine the time course for the gastrointestinal tract (GIT), absorption and subsequent bio-distribution. Q[10], a potential drug carrier for larger drugs, was evaluated for its effect on the PK profile of a dinuclear ruthenium complex (Rubb₁₂), a potential antimicrobial agent. The Rubb₁₂⊂Q[10] complex and free Rubb₁₂ were administered by i.v. to determine differences in Rubb₁₂ plasma concentrations and organ accumulation. Interestingly, the PK profiles and bio-distribution observed for Q[7] showed similarities to those of Rubb₁₂⊂Q[10]. Drug-free Q[7] has a relatively fast plasma clearance and a generally low organ accumulation except for the kidneys. Drug-free Q[8] showed a low absorption from the GIT into the blood stream but the small percentage absorbed reflected the organ accumulation of Q[7]. These results provide a better understanding of the probable PK profile and bio-distribution for a drug⊂Q[n] through the influence of the drug delivery vehicle and the positive clearance of drug-free Q[n] via the kidneys supports its potential value in future drug delivery applications.

Towards clinical translation of ligand-functionalized liposomes in targeted cancer therapy: Challenges and opportunities

The development of therapeutic resistance to targeted anticancer therapies remains a significant clinical problem, with intratumoral heterogeneity playing a key role. In this context, improving the therapeutic outcome through simultaneous targeting of multiple tumor cell subtypes within a heterogeneous tumor is a promising approach. Liposomes have emerged as useful drug carriers that can reduce systemic toxicity and increase drug delivery to the tumor site. While clinically used liposomal drug formulations show marked therapeutic advantages over free drug formulations, ligand-functionalized liposomes that can target multiple tumor cell subtypes may further improve the therapeutic efficacy by facilitating drug delivery to a broader population of tumor cells making up the heterogeneous tumor tissue. Ligand-directed liposomes enable the so-called active targeting of cell receptors via surface-attached ligands that direct drug uptake into tumor cells or tumor-associated stromal cells, and so can increase the selectivity of drug delivery. Despite promising preclinical results demonstrating improved targeting and anti-tumor effects of ligand-directed liposomes, there has been limited translation of this approach to the clinic. Key challenges for translation include the lack of established methods to scale up production and comprehensively characterize ligand-functionalized liposome formulations, as well as the inadequate recapitulation of in vivo tumors in the preclinical models currently used to evaluate their performance. Herein, we discuss the utility of recent ligand-directed liposome approaches, with a focus on dual-ligand liposomes, for the treatment of solid tumors and examine the drawbacks limiting their progression to clinical adoption.

Cryopreservation for delayed circulating tumor cell isolation is a valid strategy for prognostic association of circulating tumor cells in gastroesophageal cancer

AIM

To demonstrate the feasibility of cryopreservation of peripheral blood mononuclear cells (PBMCs) for prognostic circulating tumor cell (CTC) detection in gastroesophageal cancer.

METHODS

Using 7.5 mL blood samples collected in EDTA tubes from patients with gastroesopheagal adenocarcinoma, CTCs were isolated by epithelial cell adhesion molecule based immunomagnetic capture using the IsoFlux platform. Paired specimens taken during the same blood draw (n = 15) were used to compare number of CTCs isolated from fresh and cryopreserved PBMCs. Blood samples were processed within 24 h to recover the PBMC fraction, with PBMCs used for fresh analysis immediately processed for CTC isolation. Cryopreservation of PBMCs lasted from 2 wk to 25.2 mo (median 14.6 mo). CTCs isolated from pre-treatment cryopreserved PBMCs (n = 43) were examined for associations with clinicopathological variables and survival outcomes.

RESULTS

While there was a significant trend to a decrease in CTC numbers associated with cryopreserved specimens (mean number of CTCs 34.4 vs 51.5, P = 0.04), this was predominately in samples with a total CTC count of > 50, with low CTC count samples less affected (P = 0.06). There was no significant association between the duration of cryopreservation and number of CTCs. In cryopreserved PBMCs from patient samples prior to treatment, a high CTC count (> 17) was associated with poorer overall survival (OS) (n = 43, HR = 4.4, 95%CI: 1.7-11.7, P = 0.0013). In multivariate analysis, after controlling for sex, age, stage, ECOG performance status, and primary tumor location, a high CTC count remained significantly associated with a poorer OS (HR = 3.7, 95%CI: 1.2-12.4, P = 0.03).

CONCLUSION

PBMC cryopreservation for delayed CTC isolation is a valid strategy to assist with sample collection, transporting and processing.

Analysis of clinically relevant somatic mutations in high-risk head and neck cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma is the second most prevalent malignancy, most frequently occurring in the head and neck (head and neck cutaneous squamous cell carcinoma). Treatment of locally advanced or metastatic disease is associated with functional morbidity and disfigurement. Underlying genetic mechanisms are poorly understood. Targeted sequencing of 48 clinically relevant genes was performed on DNA extracted from formalin-fixed and paraffin-embedded high-risk primary head and neck cutaneous squamous cell carcinomas that remained non-metastatic at minimum follow-up of 24 months. Associations of somatic mutations with clinicopathologic characteristics were evaluated and compared with those described in the literature for metastatic disease. Alterations in 44 cancer-associated genes were identified. TP53 was mutated in 100% of cases; APC, ATM, ERBB4, GNAQ, KIT, RB1 and ABL1 were altered in 60% of cases. FGFR2 mutations (40%) were exclusively seen in patients with perineural invasion. MLH1 mutations were exclusively seen in the two younger patients (<45 years). Lower incidences of NOTCH1 mutations were observed compared with that described in metastatic head and neck cutaneous squamous cell carcinoma in the literature. Somatic mutations susceptible to EGFR inhibitors, and other small molecular targeted therapeutics were seen in 60% of cases. This study provides insights into somatic mutations in non-metastatic, high-risk head and neck cutaneous squamous cell carcinoma and identifies potential therapeutic targets. Alterations in FGFR2 and NOTCH1 may have roles in local and distant disease progression.

The urokinase plasminogen activation system in gastroesophageal cancer: A systematic review and meta-analysis

Background

The urokinase plasminogen activation (uPA) system is a crucial pathway for tumour invasion and establishment of metastasis. Although there is good evidence that uPA system expression is a clinically relevant biomarker in some solid tumours, its role in gastroesophageal cancer is uncertain.

Results

We identified 22 studies encompassing 1966 patients which fulfilled the inclusion criteria. uPA, uPAR, or PAI-1 expression is significantly associated with high risk clinicopathological features. High uPA expression is associated with a shorter RFS (HR 1.90 95% 1.16–3.11, p = 0.01) and OS (HR 2.21 95% CI 1.74–2.80, p < 0.0001). High uPAR expression is associated with poorer OS (HR 2.21 95%CI 1.82–2.69, p < 0.0001). High PAI-1 expression is associated with shorter RFS (HR 1.96 96% CI 1.07–3.58, p = 0.03) and OS (HR 1.84 95%CI 1.28–2.64, p < 0.0001). There was no significant association between PAI-2 expression and OS (HR 0.97 95%CI 0.48–1.94, p < 0.92) although data was limited.

Materials and Methods

We undertook a systematic review evaluating expression of uPA, urokinase plasminogen activator receptor (uPAR), plasminogen activator inhibitor-1 (PAI-1/SerpinE1) and plasminogen activator inhibitor-2 (PAI-2/SerpinB2) on primary oesophageal, gastro-oesophageal junction, and gastric adenocarcinomas. We performed a meta-analysis of clinicopathological associations, overall survival (OS) and recurrence free survival (RFS).

Conclusions

We conclude that the uPA system is a clinically relevant biomarker in primary gastroesophageal cancer, with higher expression of uPA, uPAR and PAI-1 associated with higher risk disease and poorer prognosis. This also highlights the potential utility of the uPA system as a therapeutic target for improved treatment strategies.

Plasminogen activator inhibitor type 2 inhibits cell surface associated tissue plasminogen activator in vitro

Regulation of cellular plasminogen activation is necessary for maintenance of tissue homeostasis. Despite increasing evidence for co-expression of tissue type plasminogen activator (tPA) and plasminogen activator inhibitor type-2 (PAI-2;SERPINB2) under patho/physiological conditions, the inhibition of cell-bound tPAmediated plasminogen activation by PAI-2 has not been addressed. Here we show that PAI-2 can inhibit cell-bound tPA activity in vitro and thus prevent plasmin formation. We also examined the potential involvement in this inhibition of the annexin II heterotetramer (AIIt), one of the many well characterized cell-surface co/receptors for tPA and plasminogen that efficiently promotes plasminogen activation. This receptor was of interest because AIIt has also been shown to directly bind PAI-2. Characterization of these potential interactions using purified protein systems revealed that PAI-2 directly bound AIIt via the p11 (S100A10) subunit. However, PAI-2 prevented AIIt/tPA-mediated plasminogen activation by its classic serpin inhibitory activity rather than through competition with tPA/plasminogen for binding. Further analysis showed that PAI-2 inhibited cell bound tPA-induced plasmin activity in both an AIIt-dependent and -independent manner. These data open new possibilities for further investigations regarding the regulation of cellular plasmin generation in vivo, especially in tissues where PAI-2 and tPA may be co-expressed.

SerpinB2 regulates stromal remodelling and local invasion in pancreatic cancer

Pancreatic cancer has a devastating prognosis, with an overall 5-year survival rate of ~8%, restricted treatment options and characteristic molecular heterogeneity. SerpinB2 expression, particularly in the stromal compartment, is associated with reduced metastasis and prolonged survival in pancreatic ductal adenocarcinoma (PDAC) and our genomic analysis revealed that SERPINB2 is frequently deleted in PDAC. We show that SerpinB2 is required by stromal cells for normal collagen remodelling in vitro, regulating fibroblast interaction and engagement with collagen in the contracting matrix. In a pancreatic cancer allograft model, co-injection of PDAC cancer cells and SerpinB2-/- mouse embryonic fibroblasts (MEFs) resulted in increased tumour growth, aberrant remodelling of the extracellular matrix (ECM) and increased local invasion from the primary tumour. These tumours also displayed elevated proteolytic activity of the primary biochemical target of SerpinB2-urokinase plasminogen activator (uPA). In a large cohort of patients with resected PDAC, we show that increasing uPA mRNA expression was significantly associated with poorer survival following pancreatectomy. This study establishes a novel role for SerpinB2 in the stromal compartment in PDAC invasion through regulation of stromal remodelling and highlights the SerpinB2/uPA axis for further investigation as a potential therapeutic target in pancreatic cancer.

Amorphous protein aggregates stimulate plasminogen activation, leading to release of cytotoxic fragments that are clients for extracellular chaperones

The misfolding of proteins and their accumulation in extracellular tissue compartments as insoluble amyloid or amorphous protein aggregates are a hallmark feature of many debilitating protein deposition diseases such as Alzheimer's disease, prion diseases, and type II diabetes. The plasminogen activation system is best known as an extracellular fibrinolytic system but was previously reported to also be capable of degrading amyloid fibrils. Here we show that amorphous protein aggregates interact with tissue-type plasminogen activator and plasminogen, via an exposed lysine-dependent mechanism, to efficiently generate plasmin. The insoluble aggregate-bound plasmin is shielded from inhibition by α₂-antiplasmin and degrades amorphous protein aggregates to release smaller, soluble but relatively hydrophobic fragments of protein (plasmin-generated protein fragments (PGPFs)) that are cytotoxic. In vitro, both endothelial and microglial cells bound and internalized PGPFs before trafficking them to lysosomes. Clusterin and α₂-macroglobulin bound to PGPFs to significantly ameliorate their toxicity. On the basis of these findings, we hypothesize that, as part of the in vivo extracellular proteostasis system, the plasminogen activation system may work synergistically with extracellular chaperones to safely clear large and otherwise pathological protein aggregates from the body.

Deflexifol (a novel formulation of 5FU): Phase 1 dose escalation study of infusional and bolus schedules after failure of standard treatment

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Background: 5-Fluorouracil (5FU) is administered in combination with leucovorin (LV) to enhance clinical activity. However, simultaneous administration is not feasible as 5FU and LV are chemically incompatible, so the maximum possible interaction for benefit is not achieved Deflexifol, an all in one formulation of 5FU/LV with cyclodextrin (HP-β-CD 100mg/ml, 5-FU 15mg/ml & LV 1mg/ml) at physiological pH, was developed to improve efficacy and tolerance. Methods: A phase I dose-escalation trial to assess the safety, tolerability, MTD and DLT of Deflexifol given in two schedules has been completed. Secondary objectives included the pharmacokinetic (PK) profile and efficacy outcomes. Cohorts of patients with advanced malignancy after failure of standard treatment received Deflexifol as 46-h infusion Q2W or bolus weekly x6 in a standard 3+3 phase I design with no intra-patient dose escalation from dose level 1: 375mg/m² bolus or 1200mg/m² infusional up to dose level 5: 575mg/m² bolus or 3600mg/m² infusional. PK sampling of 5FU and dihydroFU was conducted on all patients to assess PK variability and adequacy of dosing. Results: 40 patients (21 infusional, 19 bolus) with breast (7), colorectal (24), other GI (6) & NSCLC (3) received a total 293 courses of treatment. No > grade 1 toxicity was noted at 375-475 mg/m2 bolus, or at 1200-2400 mg/m2 infusion. The DLT in bolus schedule was grade 3 diarrhea and myelosuppression at 575 mg/m2, with no DLT in the infusion schedule at the maximum dose 3600 mg/m2. The MTD have been established for both treatment arms: bolus 525mg/m²; 46-h infusion 3,600mg/m², with no grade IV toxicity observed. Other grade 3 toxicities were nausea, vomiting, and raised liver function tests. 5FU PK in this mixture is similar to 5FU alone. Encouraging efficacy results were seen with partial response in 1 patient and stable disease in 23 patients. Median PFS was (12.3 wks) and OS was (24.8 wks). Conclusions: Deflexifol has little toxicity and is effective in bolus and infusion schedules at doses equal to or greater than those feasible with 5FU and LV infused separately. A first-line phase II study in combination with oxaliplatin is planned. Clinical trial information: 044867.

Deflexifol (a novel formulation of 5FU): Pharmacokinetics in a phase 1 trial in comparison to 5FU

2530

Background: Simultaneous administration of 5-fluorouracil (5FU) and leucovorin (LV) is generally not feasible as 5FU and LV are chemically incompatible (CaPO4 crystals), so the maximum possible interaction for benefit is not achieved. Deflexifol, an all in one formulation of 5FU/LV with cyclodextrin (HP-β-CD 100mg/ml, 5-FU 15mg/ml & LV 1mg/ml) at pH 7, was developed to overcome this problem. Methods: Limited sampling PK was done with dose 1 and 6 in a standard 3+3 phase I trial of Deflexifol given in two schedules (46-h infusion Q2W or bolus weekly x6) with no intrapatient dose escalation, at doses shown in Table. Sample times were infusion: 0, 2, 46h; bolus: 0, 0.2, 0.4, 1, 24h. 5FU and dihydroFU were measured as per Ackland et al, Anal Biochem 1997. 5FU AUC, clearance (CLR) and t1/2 were estimated for each patient to assess PK variability and adequacy of dosing compared to previous reports. Results: 40 patients were treated (21 infusion, 19 bolus, median age 67, 19 M, 21 F). The MTD(bolus) was 575 mg/m2, with no DLT in infusion schedule to 3600 mg/m2. PK showed substantial inter-patient variability – CLR(bolus) 21-900 L/h, t1/2 0.11-0.52 h, with intra-patient dose 6 CLR = 54-117% of dose 1, and a trend to increased AUC (mg/L.h) with dose (Table). Infusion CLR and AUC estimates were highly variable (CLR range 2-1200), with many cases with insufficient data. Compared to historical data with 5FU alone, AUC was likely subtherapeutic until 475mg/m2 bolus and for many patients with infusion <3000mg/m2. Conclusions: 5FU PK with Deflexifol is similar to 5FU alone. No evidence of saturation of kinetics over this dose range was seen, or induction of metabolism with repeated dosing. In each schedule AUC data supports the clinical impression of reduced toxicity at the same dose of 5FU. Accurate estimation of infusion PK requires more than 2 timepoints. PK in a phase II study is planned. Clinical trial information: 044867. [Table: see text]

Sidedness is prognostic in locoregional colon cancer: an analysis of 9509 Australian patients

BACKGROUND/AIM

Right sided colon cancer (RsCC) is proposed to be a distinct disease entity to left sided colon cancer (LsCC). We seek to confirm primary tumour location as an independent prognostic factor in locoregional colorectal cancer.

METHODS

All patients with stage I - III primary adenocarcinoma of colon were identified from the New South Wales (NSW) clinical cancer registry (2006-2013). Primary tumour location (RsCC vs LsCC) survival analyses were conducted using the Kaplan-Meier method, and adjusted hazard ratios for 5-year all-cause mortality (OS) and 5-year cancer specific mortality (CSS) were obtained using Cox proportional hazards regression.

RESULTS

We identified 9509 patients including 5051 patients with RsCC and 4458 with LsCC. Patients with RsCC were more likely to be older, female, have a higher Charlson comorbidity index, and have worse tumour prognostic factors. In univariate analysis of all stages combined, those patients with RsCC had a worse overall survival (OS, HR 1.20 95% CI 1.11-1.29, p < 0.0001), although this was not significant in the multivariate analysis (HR 0.96 95% CI 0.89-1.04, p = 0.35). Stage I patients with RsCC had a trend to improved OS (multivariate HR 0.84 95% CI 0.69-1.01, p = 0.07) and a significantly improved CSS (multivariate HR 0.51 95% CI 0.35-0.75, p = 0.0006). In stage II patients with RsCC there was a significantly improved OS (multivariate HR 0.85 95% CI 0.75-0.98, p = 0.02) and CSS (multivariate HR 0.59 95% CI 0.45-0.78, p = 0.0002) compared to LsCC. In stage III patients, those with RsCC had a worse OS (multivariate HR 1.13 95% CI 1.01-1.26, p = 0.032) and a trend to worse CSS (multivariate HR 1.12 95% CI 0.94-1.33, p = 0.22).

CONCLUSIONS

Primary tumour location is an important prognostic factor in locoregional colon cancer with an effect that varies by stage. RsCC is associated with lower all-cause mortality in stage II, and higher all-cause mortality in stage III.