Reviewing the genetic alterations in high-risk cutaneous squamous cell carcinoma: A search for prognostic markers and therapeutic targets

Cutaneous squamous cell carcinoma (SCC) is second only in incidence to basal cell carcinoma (BCC), effecting up to 500 000 people in the United States annually. Metastasis to regional lymph nodes occurs in approximately 5% of cases and imparts significant morbidity. Standard treatment in this group involves a combination of surgery and adjuvant radiation. Currently, there are no clinically useful biomarkers of metastatic potential in primary cutaneous SCC and histological predictors can be unreliable. The high level of mutational burden in normal UV-exposed skin has hampered the search for novel drivers of invasive disease, and indeed metastatic potential. This review outlines the clinical problems in high-risk and metastatic cutaneous SCCs, reviews the known genetic events and molecular mechanisms in high-risk primary cutaneous SCC and metastasis, and identifies avenues for further investigation and potential therapy.

Phase 1 study of infusional or bolus deflexifol (a novel formulation of 5FU, folinic acid, and cyclodextrin) after failure of standard treatment

TPS812

Background: 5FU is a commonly used anti-cancer agent first synthesized in 1957, and is now most commonly used in combination with FA, which enhances its clinical activity. Physical incompatibilities between 5FU and LV necessitate the infusion of each component separately, often through a central line due to high pH; resulting in adverse events, which leads to poor outcomes due to treatment interruption and discontinuation. A novel all in one reformulation of 5FU/LV at physiological pH has been developed as an alternative to serial administration of 5FU and LV in a high Ph solution [Locke JM, Anticancer Drugs 2009]. Preclinical testing demonstrated that the reformulation is stable bioequivalent to 5FU with reduced side effects [Stutchbury TK, Anticancer drugs 2011]. Methods: An open label phase 1 dose escalation study is underway in 2 schedules (bolus and infusion) to assess the safety and tolerability in patients with advanced malignancy after failure of standard treatment (including fluoropyrimidine regimens). To determine the maximum tolerated dose defined as: 2 out of 6 patients experience DLTs dose escalation is halted and declared DLT Dose. The previous dose level will be considered for expansion to x6 patients to confirm Maximum Tolerated Dose (MTD). Also to determine pharmacokinetic profile. Patients enrolled in Cohorts 1 to 4, have been completed without DLT. Dose-limiting toxicity (DLT) is defined as: Any Grade 3 or 4 non-haematologic toxicity (CTACE criteria). Patients developing Grade 3 or 4 diarrhoea, failing maximal anti-diarrheal medications. Febrile neutropenia, Grade 4 neutropenia > 7 days, Grade 4 thrombocytopenia > 7 days Any grade of thrombocytopenia associated with bleeding. Currently proceeding with (bolus 575mg/m2 weekly x 6, infusion 3600mg/m2/46h q2W). Limited sampling PK of 5-FU and dihydoFU is being conducted (3 at each of the 5 dose levels, doses 1 and 6). In both schedules to assess PK variability, adequacy of dosing in comparison to previous reports. The incidence of AEs and SAEs (CTACE 4.03) will be summarized by severity and relationship to study treatment. Clinical trial information: 044867.

A phase I, pharmacokinetic and pharmacodynamic study of GSK2256098, a focal adhesion kinase inhibitor, in patients with advanced solid tumors

BACKGROUND

Focal adhesion kinase (FAK) is important in cancer growth, survival, invasion, and migration. The purpose of this study was to determine the maximum tolerated dose (MTD), safety, pharmacokinetics (PK), and pharmacodynamics (PD) of the FAK inhibitor, GSK2256098, in cancer patients.

PATIENTS AND METHODS

The dose of GSK2256098 was escalated, in cohorts of patients with advanced cancer, from 80 to 1500 mg, oral twice daily (BID), until the MTD was determined. Serial blood samples were obtained from all patients, and the PK was determined. Paired tumor biopsies were obtained in select patients, and the level of phospho-FAK (pFAK) was determined.

RESULTS

Sixty-two patients (39 males, 23 females; median age 61 y.o., range 21-84) received GSK2256098. Dose-limiting toxicities of grade 2 proteinuria (1000 mg BID), grade 2 fatigue, nausea, vomiting (1250 mg BID), and grade 3 asthenia and grade 2 fatigue (1500 mg BID) were reported with the MTD identified as 1000 mg BID. The most frequent adverse events (AEs) were nausea (76%), diarrhea (65%), vomiting (58%), and decreased appetite (47%) with the majority of AEs being grades 1-2. The PK was generally dose proportional with a geometric mean elimination half-life range of 4-9 h. At the 750, 1000, and 1500 mg BID dose levels evaluated, the pFAK, Y397 autophosphorylation site, was reduced by ∼80% from baseline. Minor responses were observed in a patient with melanoma (-26%) and three patients with mesothelioma (-13%, -15%, and -17%). In the 29 patients with recurrent mesothelioma, the median progression-free survival was 12 weeks with 95% CI 9.1, 23.4 weeks (23.4 weeks merlin negative, n = 14; 11.4 weeks merlin positive, n = 9; 10.9 weeks merlin status unknown, n = 6).

CONCLUSIONS

GSK2256098 has an acceptable safety profile, has evidence of target engagement at doses at or below the MTD, and has clinical activity in patients with mesothelioma, particularly those with merlin loss.

PZP and PAI-2: Structurally-diverse, functionally similar pregnancy proteins?

Pregnancy zone protein (PZP) and plasminogen activator inhibitor type 2 (PAI-2) are two multifunctional proteins that are elevated in normal pregnancy and numerous other inflammatory states. Both proteins were originally identified as protease inhibitors, but current evidence supports the notion that they may also function as modulators of T-helper cells and/or extracellular chaperones. Exacerbated inflammation, fibrinolytic disturbances and misfolded proteins are all implicated in the pathology of preeclampsia, a leading cause of maternal and foetal mortality and morbidity. Notably, reduced levels of PZP or PAI-2 are associated with preeclampsia and clarification of their diverse functions in normal pregnancy could provide much needed insight regarding the pathogenesis of this disorder. Given that inflammation and protein misfolding underlie the pathology of a very large number of disorders, the contributions of PZP and PAI-2 to extracellular proteostasis and immunoregulation could be broad-reaching.

Circulating tumour cells in regionally metastatic cutaneous squamous cell carcinoma: A pilot study

BACKGROUND

Circulating tumour cells (CTCs) are increasingly being used in the surveillance of cancer, allowing for potential early detection and real-time monitoring of disease progression. The presence of CTCs in patients with metastatic cutaneous head and neck squamous cell carcinoma (cHNSCC) has not been evaluated.

RESULTS

CTCs were detected in eight of ten patients with regional metastatic cHNSCC (80%; range 1-44 cells/9 mL blood). CTMs were detected in three of ten patients (30%, range 1-4 cells/9 mL blood).

METHODS

Preoperative blood samples from ten patients with nodal metastases from cutaneous squamous cell carcinomas (cSCC) were analyzed using the IsoFluxTM System for the detection and enumeration of CTCs and circulating tumour microemboli (CTMs).

CONCLUSIONS

For the first time CTCs have been detected in patients with nodal metastases from cHNSCC. Further work is required to understand their prognostic significance and potential to directly influence clinical practice.

A phase I, dose escalation, pharmacodynamic, pharmacokinetic, and food-effect study of α2 integrin inhibitor E7820 in patients with advanced solid tumors

Introduction E7820 is an orally administered sulfonamide that inhibits alfa-2-integrin mRNA expression. Pre-clinically E7820 showed tumor anti-angiogenic effects in various tumor cell lines and xenograft mouse models. Human daily dosing of 100 mg QD had previously been shown to be safe and tolerable. Methods The study consisted of two parts: Part A (food effect) and Part B (determination of maximum tolerated dose (MTD) for bi-daily (BID) dosing). E7820 dosing started at 50 mg BID with planned escalation to 60, 80 and 100 mg BID every 28 days. Results Fifteen patients were enrolled in Part A and 26 in Part B. The most frequent adverse events of all grades were constipation, diarrhea, nausea, and fatigue while anemia, neutropenia, and fatigue were most frequent grade ≥3 toxicities. At dose-level 60 mg BID, two patients experienced dose-limiting toxicities (grade 3 neutropenic sepsis and grade 4 neutropenia). Therefore the recommended dose (RD) was 50 mg BID. Food had no effect on E7820 exposure. E7820 exposure following twice daily administration was dose-proportional. Expression of platelet integrin-α2 measured as a response biomarker in Part B, generally decreased by a median 7.7 % from baseline following treatment with 50 mg BID E7820. Reduction was most pronounced within 1-week post treatment. The median duration of treatment was median 54, range 20-111 days. The best overall response in any treatment group was stable disease (SD): 23.1 % in Part A (100 mg QD); at the RD 66.7 % (12 of 18 patients) and 40 % in the 60 mg BID group in Part B.

CONCLUSIONS

Food had no effect on E7820 exposure. A dose of 50 mg BID was considered the MTD. Treatment with E7820 is safe and tolerable with 2/3 of patients (66.7 %) at MTD having SD as their best response.

N-alkylated isatins evade P-gp mediated efflux and retain potency in MDR cancer cell lines

The search for novel anticancer therapeutics with the ability to overcome multi-drug resistance (MDR) mechanisms is of high priority. A class of molecules that show potential in overcoming MDR are the N-alkylated isatins. In particular 5,7-dibromo-N-alkylisatins are potent microtubule destabilizing agents that act to depolymerize microtubules, induce apoptosis and inhibit primary tumor growth in vivo. In this study we evaluated the ability of four dibrominated N-alkylisatin derivatives and the parent compound, 5,7-dibromoisatin, to circumvent MDR. All of the isatin-based compounds examined retained potency against the MDR cell lines; U937VbR and MES-SA/Dx5 and displayed bioequivalent dose-dependent cytotoxicity to that of the parental control cell lines. We show that one mechanism by which the isatin-based compounds overcome MDR is by circumventing P-glycoprotein (P-gp) mediated drug efflux. Thus, as the isatin-based compounds are not susceptible to extrusion from P-gp overexpressing tumor cells, they represent a promising alternative strategy as a stand-alone or combination therapy for treating MDR cancer.

Abstract 2251: Serglycin proteoglycan promotes progression and metastasis of triple-negative breast cancers

Introduction. Triple-negative breast cancers have a propensity to metastasize and a poor outcome relative to other breast cancer subtypes. No molecularly targeted therapies exist for triple-negative disease and the standard of care for remains surgery followed by adjuvant radiotherapy and/or chemotherapy. Therefore, new therapies that target the molecular alterations present in triple-negative tumors are needed to either prevent metastatic dissemination or kill micrometastatic lesions at distant sites. The serglycin gene encodes a large secreted proteoglycan decorated with chondroitin sulfate modifications and expressed primarily by the hematopoietic system.1 While serglycin was recently shown to be expressed by mammary epithelial cells2, its role in breast oncogenesis is unclear.

Methods. Serglycin expression was analyzed by RNA-based (qRT-PCR) and protein-based (immunohistochemistry) methods3. Serglycin expression was specifically knocked down in triple-negative breast cancer lines (MDA-MB-231_HM4, SUM159) by shRNA technology using the pGIPZ lentiviral system. Genetically engineered cells were assessed in vitro using standard assays. Tumor growth and spontaneous metastasis to lung, liver and spleen was analyzed in vivo by orthotopic inoculation of cells into Nod.Scid.IL-2Rgamma-null (NSG)5 immuno-deficient mice.

Results. Serglycin was found to over-expressed in a subset of triple-negative breast cancers as well as in several metastatic triple-negative/claudin-low breast cancer cell lines including MDA-MB-231, SUM159 and Hs578T. Knockdown of serglycin was engineered in highly-metastatic MDA-MB-231_HM (231_HM) cells and in a metastatic variant of SUM159 cells. In vivo experiments showed that knockdown of serglycin reduced the growth rate of primary 231_HM tumours implanted in the mammary fat pads of mice. Moreover, following resection of the primary tumours, spontaneous metastasis to lung, liver and spleen was reduced in serglycin-depleted 231_HM cells.

Conclusions. The hematopoietic proteoglycan serglycin is over-expressed in a subset of triple-negative breast cancers and may represent a novel target for anti-cancer therapy.

References:

1. Korpetinou A, et al., Serglycin: at the crossroad of inflammation and malignancy. Front Oncol. 2014 3:327

2. Korpetinou A, et al., Serglycin is implicated in the promotion of aggressive phenotype of breast cancer cells. PLoS One 2013 8:e78157

3. Li XJ, et al., Serglycin is a theranostic target in nasopharyngeal carcinoma that promotes metastasis. Cancer Res. 2011 71:3162-3172

4. Chang XZ, et al., Identification of the functional role of peroxiredoxin 6 in the progression of breast cancer. Breast Cancer Res. 2007 9:R76

5. Shultz LD, et al., Human lymphoid and myeloid cell development in NOD/LtSz-scid IL2R gamma null mice engrafted with mobilized human hemopoietic stem cells. J Immunol. 2005 174:6477-6489

Citation Format: Cameron N. Johnstone, Nathaniel Harris, Marie Ranson, Anil K. Rustgi, Robin L. Anderson. Serglycin proteoglycan promotes progression and metastasis of triple-negative breast cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2251. doi:10.1158/1538-7445.AM2015-2251

SerpinB2 (PAI-2) Modulates Proteostasis via Binding Misfolded Proteins and Promotion of Cytoprotective Inclusion Formation

SerpinB2 (PAI-2), a member of the clade B family of serine protease inhibitors, is one of the most upregulated proteins following cellular stress. Originally described as an inhibitor of urokinase plasminogen activator, its predominant cytoplasmic localisation suggests an intracellular function. SerpinB2 has been reported to display cytoprotective properties in neurons and to interact with intracellular proteins including components of the ubiquitin-proteasome system (UPS). In the current study we explored the potential role of SerpinB2 as a modulator of proteotoxic stress. Initially, we transiently transfected wild-type SerpinB2 and SerpinB2-/- murine embryonic fibroblasts (MEFs) with Huntingtin exon1-polyglutamine (fused C-terminally to mCherry). Inclusion body formation as result of Huntingtin aggregation was evident in the SerpinB2 expressing cells but significantly impaired in the SerpinB2-/- cells, the latter concomitant with loss in cell viability. Importantly, recovery of the wild-type phenotype and cell viability was rescued by retroviral transduction of SerpinB2 expression. SerpinB2 modestly attenuated Huntingtin and amyloid beta fibril formation in vitro and was able to bind preferentially to misfolded proteins. Given the modest chaperone-like activity of SerpinB2 we tested the ability of SerpinB2 to modulate UPS and autophagy activity using a GFP reporter system and autophagy reporter, respectively. Activity of the UPS was reduced and autophagy was dysregulated in SerpinB2-/- compared to wild-type MEFs. Moreover, we observed a non-covalent interaction between ubiquitin and SerpinB2 in cells using GFP-pulldown assays and bimolecular fluorescence complementation. We conclude that SerpinB2 plays an important role in proteostasis as its loss leads to a proteotoxic phenotype associated with an inability to compartmentalize aggregating proteins and a reduced capacity of the UPS.

AZD3514, an oral selective androgen receptor down-regulator in patients with castration-resistant prostate cancer - results of two parallel first-in-human phase I studies

BACKGROUND

AZD3514 is a first-in-class, orally bio-available, androgen-dependent and -independent androgen receptor inhibitor and selective androgen-receptor down-regulator (SARD).

METHODS

In study 1 and 2, castration-resistant prostate cancer (CRPC) patients (pts) were initially recruited into a once daily (QD) oral schedule (A). In study 1, pharmacokinetic assessments led to twice daily (BID) dosing (schedule B) to increase exposure. Study 2 explored a once daily schedule.

RESULTS

In study 1, 49 pts were treated with escalating doses of AZD3514 (A 35 pts, B 14 pts). Starting doses were 100 mg (A) and 1000 mg (B). The AZD3514 formulation was switched from capsules to tablets at 1000 mg QD. 2000 mg BID was considered non-tolerable due to grade (G) 2 toxicities (nausea [N], vomiting [V]). No adverse events (AEs) met the dose-limiting toxicity (DLT) definition. Thirteen pts received AZD3514 in study 2, with starting doses of 250 mg QD. The most frequent drug-related AEs were N: G1/2 in 55/70 pts (79 %); G3 in 1 pt (1.4 %); & V: G1/2 in 34/70 pts (49 %) & G3 in 1 pt (1.4 %). PSA declines (≥50 %) were documented in 9/70 patients (13 %). Objective soft tissue responses per RECIST1.1 were observed in 4/24 (17 %) pts in study 1.

CONCLUSION

AZD3514 has moderate anti-tumour activity in pts with advanced CRPC but with significant levels of nausea and vomiting. However, anti-tumour activity as judged by significant PSA declines, objective responses and durable disease stabilisations, provides the rationale for future development of SARD compounds.

HER2 and uPAR cooperativity contribute to metastatic phenotype of HER2-positive breast cancer

Human epidermal growth factor receptor type 2 (HER2)-positive breast carcinoma is highly aggressive and mostly metastatic in nature though curable/manageable in part by molecular targeted therapy. Recent evidence suggests a subtype of cells within HER2-positive breast tumors that concomitantly expresses the urokinase plasminogen activator receptor (uPAR) with inherent stem cell/mesenchymal-like properties promoting tumor cell motility and a metastatic phenotype. This HER-positive/uPAR-positive subtype may be partially responsible for the failure of HER2-targeted treatment strategies. Herein we discuss and substantiate the cumulative preclinical and clinical evidence on HER2-uPAR cooperativity in terms of gene co-amplification and/or mRNA/protein co-overexpression. We then propose a regulatory signaling model that we hypothesize to maintain upregulation and cooperativity between HER2 and uPAR in aggressive breast cancer. An improved understanding of the HER2/uPAR interaction in breast cancer will provide critical biomolecular information that may help better predict disease course and response to therapy.

Plasmin(ogen) acquisition by group A Streptococcus protects against C3b-mediated neutrophil killing

The globally significant human pathogen group A Streptococcus (GAS) sequesters the host protease plasmin to the cell surface during invasive disease initiation. Recent evidence has shown that localized plasmin activity prevents opsonization of several bacterial species by key components of the innate immune system in vitro. Here we demonstrate that plasmin at the GAS cell surface resulted in degradation of complement factor C3b, and that plasminogen acquisition is associated with a decrease in C3b opsonization and neutrophil-mediated killing in vitro. Furthermore, the ability to acquire cell surface plasmin(ogen) correlates directly with a decrease in C3b opsonization, neutrophil phagocytosis, and increased bacterial survival in a humanized plasminogen mouse model of infection. These findings demonstrate that localized plasmin(ogen) plays an important role in facilitating GAS escape from the host innate immune response and increases bacterial virulence in the early stages of infection.

A key role for the urokinase plasminogen activator (uPA) in invasive Group A streptococcal infection

Recruitment of the serine protease plasmin is central to the pathogenesis of many bacterial species, including Group A streptococcus (GAS), a leading cause of morbidity and mortality globally. A key process in invasive GAS disease is the ability to accumulate plasmin at the cell surface, however the role of host activators of plasminogen in this process is poorly understood. Here, we demonstrate for the first time that the urokinase-type plasminogen activator (uPA) contributes to plasmin recruitment and subsequent invasive disease initiation in vivo. In the absence of a source of host plasminogen activators, streptokinase (Ska) was required to facilitate cell surface plasmin acquisition by GAS. However, in the absence of Ska, host activators were sufficient to promote cell surface plasmin acquisition by GAS strain 5448 during incubation with plasminogen or human plasma. Furthermore, GAS were able mediate a significant increase in the activation of zymogen pro-uPA in human plasma. In order to assess the contribution of uPA to invasive GAS disease, a previously undescribed transgenic mouse model of infection was employed. Both C57/black 6J, and AlbPLG1 mice expressing the human plasminogen transgene, were significantly more susceptible to invasive GAS disease than uPA−/− mice. The observed decrease in virulence in uPA−/−mice was found to correlate directly with a decrease in bacterial dissemination and reduced cell surface plasmin accumulation by GAS. These findings have significant implications for our understanding of GAS pathogenesis, and research aimed at therapeutic targeting of plasminogen activation in invasive bacterial infections.

Subversion of the host fibrinolytic system by bacterial pathogens is recognised as a key process in severe disease initiation. Co-opting of plasmin by bacteria contributes to tissue destruction and bacterial dissemination, both hallmarks of invasive Group A streptococcal disease, and research aimed at therapeutic targeting of the nexus between group A streptococcus and the fibrinolytic system is increasing. The host plasminogen activator uPA is found at the surface of cells that contribute to epithelial and innate immune defense against bacterial infection, and may contribute to bacterial recruitment of plasmin, however, the role of uPA in group A streptococcal infection is not well characterised. Here, we describe for the first time the key role played by uPA in invasive group A streptococcal disease. The ability of this pathogen to cause severe infection, even in the absence of the bacterial plasminogen activator streptokinase, has significant implications for the development of therapeutics to control invasive bacterial infection.