Carfilzomib Promotes the Unfolded Protein Response and Apoptosis in Cetuximab-Resistant Colorectal Cancer.

Cetuximab is a common treatment option for patients with wild-type K-Ras colorectal carcinoma. However, patients often display intrinsic resistance or acquire resistance to cetuximab following treatment. Here we generate two human CRC cells with acquired resistance to cetuximab that are derived from cetuximab-sensitive parental cell lines. These cetuximab-resistant cells display greater in vitro proliferation, colony formation and migration, and in vivo tumour growth compared with their parental counterparts. To evaluate potential alternative therapeutics to cetuximab-acquired-resistant cells, we tested the efficacy of 38 current FDA-approved agents against our cetuximab-acquired-resistant clones. We identified carfilzomib, a selective proteosome inhibitor to be most effective against our cell lines. Carfilzomib displayed potent antiproliferative effects, induced the unfolded protein response as determined by enhanced CHOP expression and ATF6 activity, and enhanced apoptosis as determined by enhanced caspase-3/7 activity. Overall, our results indicate a potentially novel indication for carfilzomib: that of a potential alternative agent to treat cetuximab-resistant colorectal cancer.

Association Between Smoking Status and the Efficacy and Safety of Tofacitinib in Patients with Ulcerative Colitis.

Background: Tofacitinib is an oral Janus kinase inhibitor for the treatment of ulcerative colitis (UC). This analysis assessed the impact of cigarette smoking on tofacitinib efficacy and safety in the UC clinical program. Methods: Efficacy endpoints and adverse events (AEs) were evaluated by smoking status (ever smokers [current and ex-smokers] and never smokers) in the phase (P)2 induction study (baseline demographics and safety only), P3 studies (OCTAVE Induction 1&2, OCTAVE Sustain, OCTAVE Open), and P3/4b RIVETING study. Results: This post hoc analysis included 1156 patients (ever smokers, n = 416 [36.0%; current smokers, n = 59 (5.1%); ex-smokers, n = 357 (30.9%)]; never smokers, n = 740 [64.0%]; median [range] treatment duration 654 [1-2712] and 615.5 [1-2850] days, respectively). Similar proportions of ever smokers and never smokers achieved efficacy endpoints. AEs were reported in 88.7% of ever smokers and 83.8% of never smokers. Overall, 60.6% of ever smokers had an infection (serious infections, 5.5%; herpes zoster [nonserious and serious], 10.8%; Clostridioides difficile infection, 12.0%; lower respiratory tract infection, 19.5%: corresponding values among never smokers were 53.1%, 3.9%, 6.8%, 8.5%, and 11.4%). Major adverse cardiovascular events were reported in 1.0% of ever smokers and 0.7% of never smokers and thromboembolism events (venous and arterial) in 1.0% of ever smokers and 0.9% never smokers. Deaths, malignancies (excluding non-melanoma skin cancer [NMSC]), and NMSC occurred infrequently in ever smokers (0.5%, 2.5%, and 3.7%, respectively) and never smokers (0.1%, 1.5%, and 1.0%, respectively). Colorectal cancer was reported in 0.6% of never smokers; no cases occurred in ever smokers. Conclusions: Efficacy and safety of tofacitinib were generally similar in ever smokers and never smokers. Overall, serious AEs and, as expected, infections were more frequent in ever smokers versus never smokers. This may inform treatment selection and monitoring strategies. ClinicalTrialsgov: NCT00787202;NCT01465763;NCT01458951;NCT01458574;NCT01470612;NCT03281304.

In Vitro and In Vivo Toxicity and Biodistribution of Paclitaxel-Loaded Cubosomes as a Drug Delivery Nanocarrier: A Case Study Using an A431 Skin Cancer Xenograft Model.

Cubosomes with an internal three-dimensional (3D) periodic and porous particulate nanostructure have emerged as a promising drug delivery system for hydrophobic small molecules as well as large biomolecules over the past several decades. Limited understanding of their safety profiles and biodistribution, however, hinders clinical translation. This study used monoolein-based cubosomes stabilized by Pluronic F127 and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide(polyethylene glycol)] polymers to encapsulate paclitaxel (PTX) as a model drug and investigated the in vitro cytotoxicity, in vivo acute response, and whole body biodistribution of the developed nanoparticles. Comparison of the PTX and nanoparticle cytotoxicity in two-dimensional and 3D spheroid cell models revealed distinct differences, with the cells in the 3D model found to be more tolerable to unloaded PTX as well as the PTX-loaded nanoparticle form. One-time intraperitoneal (i.p.) injection of unloaded cubosomes were generally well tolerated up to 400 mg/kg. Using the A431 skin cancer xenograft model, in vivo imaging studies showed the preferential accumulation of PTX-loaded cubosomes at the tumor sites following i.p. injection. Lastly, average tumor size was reduced by approximately 50% in the nanoparticle-based treatment group compared to the unloaded PTX drug group. The study provides significant information on the biological response of cubosomes and highlights their potential as a versatile drug delivery platform for safe and effective delivery of chemotherapeutic drugs.

HPV16/18 prevalence in high-grade cervical lesions in an Australian population offered catch-up HPV vaccination.

OBJECTIVES: Using laser capture microdissection (LCM) and sensitive human papillomavirus (HPV) genotyping, we aimed to determine the distribution of vaccine-preventable types in cervical intraepithelial neoplasia grade 3 (CIN3) lesions and adenocarcinoma in situ (AIS) in young women in Victoria, Australia, offered catch-up HPV vaccination, as a baseline for ongoing vaccine impact monitoring. We also compared findings with available pre-vaccination estimates from women with HPV detected on concurrently-collected cytology samples. METHODS: Consecutive histologically-confirmed CIN3/AIS biopsies were collected between May 2011 and December 2014 from vaccine-eligible women (born after 30th June 1981). Genotypes present in whole tissue sections (WTS) were determined by a sensitive reverse hybridisation assay; RHA kit HPV SPF10-LiPA25, v1 (Labo Bio-medical Products). Where multiple genotypes were detected, lesions were isolated using LCM and genotyped. Cervical cytology samples from a pre-vaccine cohort had been previously collected and genotyped using HPV Linear Array HPV Genotyping Test (Roche Diagnostics). Mixed-genotype detections in this cohort were resolved to single-lesion-attributable genotypes using hierarchical attribution. RESULTS: Overall, 213 and 530 cases were included from pre- and post-vaccine time-periods, respectively. In 18-25 year-olds, the proportion of HPV16/18-positive CIN3/AIS decreased significantly over time from 69% in 2001-2005 (pre-vaccine), to 62% in 2011-2012 (post-vaccine), to 47% in 2013-2014 (p-trend = 0.004). There was no significant change in HPV16/18 in 26-32 year-olds (p-trend = 0.15). In 2013/14, nonavalent vaccine types accounted for 80% of CIN3/AIS in 18-25 year old women and 90% in 26-32 year old women. CONCLUSION: Four to 8 years following implementation of HPV vaccination in Australia, approximately 70% of CIN3/AIS in young women was due to HPV16/18. Our data, despite some limitations due to change in methods between pre- and post-vaccine periods, suggests that for vaccine-eligible women aged 18-25 at the time of biopsy, the proportion of HPV16/18-attributable CIN3/AIS lesions is significantly declining post-vaccination.

Assessment of attribution algorithms for resolving CIN3-related HPV genotype prevalence in mixed-genotype biopsy specimens using laser capture microdissection as the reference standard.

To make accurate determinations regarding potential and actual impact of HPV vaccine programs, precise estimates of genotype-specific contributions to disease are required for pre- and post-vaccine populations. Definitive determination of lesion-specific genotypes, particularly where multiple genotypes are detected in a sample, can be technically demanding and resource intensive; therefore, most prevalence studies use mathematical algorithms to adjust for multiple genotype detections. There are currently several algorithms, which can produce genotype estimates within a wide range of variability. The use of these for cervical cytology samples has recently been assessed for accuracy against a definitive reference standard, but none have yet been assessed for multiple-genotype-containing whole biopsy specimens. Using laser capture microdissection (LCM) on biopsy samples, lesion-specific genotype prevalence data were generated for a cohort of 516 young Australian women (aged 18-32 years) with cervical intraepithelial neoplasia grade 3 or adenocarcinoma in situ. Using whole tissue section genotype data from the same cohort, including 71 (13.7%) with multiple genotypes, lesion-associated genotype prevalence was estimated using four different attribution algorithms. The proportion of lesions attributable to HPV16 and HPV18 by LCM were 58.4% and 5%, respectively; hierarchical, proportional, single type/minimum and any type/maximum attribution estimates were comparable across genotypes. For analyses utilising whole tissue biopsy cervical specimens, attribution estimates are appropriate for estimating the proportional contribution of individual genotypes to lesions in a population.

mTOR Signalling in Head and Neck Cancer: Heads Up.

The mammalian target of rapamycin (mTOR) signalling pathway is a central regulator of metabolism in all cells. It senses intracellular and extracellular signals and nutrient levels, and coordinates the metabolic requirements for cell growth, survival, and proliferation. Genetic alterations that deregulate mTOR signalling lead to metabolic reprogramming, resulting in the development of several cancers including those of the head and neck. Gain-of-function mutations in EGFR, PIK3CA, and HRAS, or loss-of-function in p53 and PTEN are often associated with mTOR hyperactivation, whereas mutations identified from The Cancer Genome Atlas (TCGA) dataset that potentially lead to aberrant mTOR signalling are found in the EIF4G1, PLD1, RAC1, and SZT2 genes. In this review, we discuss how these mutant genes could affect mTOR signalling and highlight their impact on metabolic processes, as well as suggest potential targets for therapeutic intervention, primarily in head and neck cancer.

Ponatinib: a novel multi-tyrosine kinase inhibitor against human malignancies.

Human malignancies are often the result of overexpressed and constitutively active receptor and non-receptor tyrosine kinases, which ultimately lead to the mediation of key tumor-driven pathways. Several tyrosine kinases (ie, EGFR, FGFR, PDGFR, VEGFR), are aberrantly activated in most common tumors, including leukemia, glioblastoma, gastrointestinal stromal tumors, non-small-cell lung cancer, and head and neck cancers. Iclusig™ (ponatinib, previously known as AP24534) is an orally active multi-tyrosine kinase inhibitor and is currently approved by the US Food and Drug Administration for patients with chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, specifically targeting the BCR-ABL gene mutation, T315I. Due to ponatinib's unique multi-targeted characteristics, further studies have demonstrated its ability to target other important tyrosine kinases (FGFR, PDGFR, SRC, RET, KIT, and FLT1) in other human malignancies. This review focuses on the available data of ponatinib and its molecular targets for treatment in various cancers, with a discussion on the broader potential of this agent in other cancer indications.

Loss of GRHL3 leads to TARC/CCL17-mediated keratinocyte proliferation in the epidermis.

Identifying soluble factors that influence epidermal integrity is critical for the development of preventative and therapeutic strategies for disorders such as ichthyosis, psoriasis, dermatitis and epidermal cancers. The transcription factor Grainyhead-like 3 (GRHL3) is essential for maintaining barrier integrity and preventing development of cutaneous squamous cell carcinoma (SCC); however, how loss of this factor, which in the skin is expressed exclusively within suprabasal epidermal layers triggers proliferation of basal keratinocytes, had thus far remained elusive. Our present study identifies thymus and activation-regulated chemokine (TARC) as a novel soluble chemokine mediator of keratinocyte proliferation following loss of GRHL3. Knockdown of GRHL3 in human keratinocytes showed that of 42 cytokines examined, TARC was the only significantly upregulated chemokine. Mouse skin lacking Grhl3 presented an inflammatory response with hallmarks of TARC activation, including heightened induction of blood clotting, increased infiltration of mast cells and pro-inflammatory T cells, increased expression of the pro-proliferative/pro-inflammatory markers CD3 and pSTAT3, and significantly elevated basal keratinocyte proliferation. Treatment of skin cultures lacking Grhl3 with the broad spectrum anti-inflammatory 5-aminosalicylic acid (5ASA) partially restored epidermal differentiation, indicating that abnormal keratinocyte proliferation/differentiation balance is a key driver of barrier dysfunction following loss of Grhl3, and providing a promising therapeutic avenue in the treatment of GRHL3-mediated epidermal disorders.

Ponatinib Inhibits Multiple Signaling Pathways Involved in STAT3 Signaling and Attenuates Colorectal Tumor Growth.

Signal transducer and activator of transcription 3 (STAT3) signaling is a major driver of colorectal cancer (CRC) growth, however therapeutics, which can effectively target this pathway, have so far remained elusive. Here, we performed an extensive screen for STAT3 inhibitors among a library of 1167 FDA-approved agents, identifying Ponatinib as a lead candidate. We found that Ponatinib inhibits STAT3 activity driven by EGF/EGFR, IL-6/IL-6R and IL-11/IL-11R, three major ligand/receptor systems involved in CRC development and progression. Ponatinib was able to inhibit CRC migration and tumor growth in vivo. In addition, Ponatinib displayed a greater ability to inhibit STAT3 activity and mediated superior anti-proliferative efficacy compared to five FDA approved SRC and Janus Kinase (JAK) inhibitors. Finally, long-term exposure of CRC cells to Ponatinib, Dasatinib and Bosutinib resulted in acquired resistance to Dasatinib and Bosutinib occurring within six weeks. However, acquired resistance to Ponatinib was observed after long-term exposure of >4 months. Overall, our results identify a novel anti-STAT3 property of Ponatinib and thus, Ponatinib offers a potential therapeutic strategy for CRC.

Paclitaxel-Loaded Self-Assembled Lipid Nanoparticles as Targeted Drug Delivery Systems for the Treatment of Aggressive Ovarian Cancer.

Chemotherapy using cytotoxic agents, such as paclitaxel (PTX), is one of the most effective treatments for advanced ovarian cancer. However, due to nonspecific targeting of the drug and the presence of toxic solvents required for dissolving PTX prior to injection, there are several serious side effects associated with this treatment. In this study, we explored self-assembled lipid-based nanoparticles as PTX carriers, which were able to improve its antitumour efficacy against ovarian cancer. The nanoparticles were also functionalized with epidermal growth factor receptor (EGFR) antibody fragments to explore the benefit of tumor active targeting. The formulated bicontinuous cubic- and sponge-phase nanoparticles, which were stabilized by Pluronic F127 and a lipid poly(ethylene glycol) stabilizer, showed a high capacity of PTX loading. These PTX-loaded nanoparticles also showed significantly higher cytotoxicity than a free drug formulation against HEY ovarian cancer cell lines in vitro. More importantly, the nanoparticle-based PTX treatments, with or without EGFR targeting, reduced the tumor burden by 50% compared to PTX or nondrug control in an ovarian cancer mouse xenograft model. In addition, the PTX-loaded nanoparticles were able to extend the survival of the treatment groups by up to 10 days compared to groups receiving free PTX or nondrug control. This proof-of-concept study has demonstrated the potential of these self-assembled lipid nanomaterials as effective drug delivery nanocarriers for poorly soluble chemotherapeutics, such as PTX.

STAT3 signaling mediates tumour resistance to EGFR targeted therapeutics.

Several EGFR inhibitors are currently undergoing clinical assessment or are approved for the clinical management of patients with varying tumour types. However, treatment often results in a lack of response in many patients. The majority of patients that initially respond eventually present with tumours that display acquired resistance to the original therapy. A large number of receptor tyrosine and intracellular kinases have been implicated in driving signaling that mediates this tumour resistance to anti-EGFR targeted therapy, and in a few cases these discoveries have led to overall changes in prospective tumour screening and clinical practice (K-RAS in mCRC and EGFR T790M in NSCLC). In this mini-review, we specifically focus on the role of the STAT3 signaling axis in providing both intrinsic and acquired resistance to inhibitors of the EGFR. We also focus on STAT3 pathway targeting in an attempt to overcome resistance to anti-EGFR therapeutics.

The role of STAT3 signaling in mediating tumor resistance to cancer therapy.

Signal transducer and activator of transcription 3 (STAT3) is activated in many cancer types and can regulate pathways involving tumorigenesis, cell proliferation, cell survival and angiogenesis. Upstream cytokine signaling through multiple trans-membrane receptors can enhance the activation of STAT3 and promote tumor progression. Importantly, STAT3 activation can also be induced via the Janus-activated kinase 1/2 (JAK1/2) and Src family kinases. Target-specific drug therapies have been developed to inhibit many of the upstream receptor and non-receptor activators of STAT3 and are now approved for clinical use. Recently, resistance to standard-of-care therapies has been linked to constitutive or unabated STAT3 activation, suggesting that combination therapy with STAT3 inhibitors may be of clinical benefit. Furthermore, STAT3 activity has also been shown to regulate self-renewal of cancer stem cells that are often refractory to chemotherapy treatment. This review will focus on STAT3 mediated resistance to cancer therapy and discuss strategies to overcome this resistance.