To investigate the use of liposomal irinotecan (Irinophore C™) plus or minus 5-fluorouracil (5-FU) for the treatment of colorectal cancer.
The effect of irinotecan (IRI) and/or 5-FU exposure times on ...cytotoxicity was assessed in vitro against HT-29 or LS174T human colon carcinoma cells. The pharmacokinetics and biodistribution of Irinophore C™ (IrC™) and 5-FU, administered alone or in combination, were compared in vivo. A subcutaneous model of HT-29 human colorectal cancer in Rag2-M mice was utilized to assess the efficacy of IrC™ alone, and in combination with 5-FU.
The cytotoxicity of IRI and 5-FU were strongly dependent on exposure time. Synergistic interactions were observed following prolonged exposure to IRI/5-FU combinations. Pharmacokinetics/biodistribution studies demonstrated that the 5-FU elimination rate was decreased significantly when 5-FU was co-administered intravenously with IrC™, versus alone. Significant decreases in 5-FU elimination were also observed in plasma, with an associated increase of 5-FU in some tissues when 5-FU was given by intraperitoneal injection and IrC™ was given intravenously. The elimination of IrC™ was not significantly different when administered alone or in combination with 5-FU. Therapeutic studies demonstrated that single agent IrC™ was significantly more effective than the combination of IRI/5-FU; surprisingly, IrC™/5-FU combinations were no more effective than IrC™ alone. The administration of combinations of 5-FU (16 mg/kg) and IrC™ (60 mg IRI/kg) showed increased toxicity when compared to IrC™ alone. Treatment with IrC™ alone (60 mg IRI/kg) delayed the time required for a 5-fold increase in initial tumor volume to day 49, compared to day 23 for controls. When IrC™ (40 mg IRI/kg) was used in combination with 5-FU (16 mg/kg), the time to increase tumor volume 5-fold was 43 days, which was comparable to that achieved when using IrC™ alone (40 mg IRI/kg).
Single agent IrC™ was well tolerated and has significant therapeutic potential. IrC™ may be a suitable replacement for IRI treatment, but its use with free 5-FU is complicated by IrC™-engendered changes in 5-FU pharmacokinetics/biodistribution which are associated with increased toxicity when using the combination.
Autophagy, a lysosome-mediated degradation and recycling process, functions in advanced malignancies to promote cancer cell survival and contribute to cancer progression and drug resistance. While ...various autophagy inhibition strategies are under investigation for cancer treatment, corresponding patient selection criteria for these autophagy inhibitors need to be developed. Due to its central roles in the autophagy process, the cysteine protease ATG4B is one of the autophagy proteins being pursued as a potential therapeutic target. In this study, we investigated the expression of ATG4B in breast cancer, a heterogeneous disease comprised of several molecular subtypes. We examined a panel of breast cancer cell lines, xenograft tumors, and breast cancer patient specimens for the protein expression of ATG4B, and found a positive association between HER2 and ATG4B protein expression. We showed that HER2-positive cells, but not HER2-negative breast cancer cells, require ATG4B to survive under stress. In HER2-positive cells, cytoprotective autophagy was dependent on ATG4B under both starvation and HER2 inhibition conditions. Combined knockdown of ATG4B and HER2 by siRNA resulted in a significant decrease in cell viability, and the combination of ATG4B knockdown with trastuzumab resulted in a greater reduction in cell viability compared to trastuzumab treatment alone, in both trastuzumab-sensitive and -resistant HER2 overexpressing breast cancer cells. Together these results demonstrate a novel association of ATG4B positive expression with HER2 positive breast cancers and indicate that this subtype is suitable for emerging ATG4B inhibition strategies.
Lung cancer is a heterogeneous disease consisting of multiple histological subtypes each driven by unique genetic alterations. Despite the development of targeted therapies that inhibit the oncogenic ...mutations driving a subset of lung cancer cases, there is a paucity of effective treatments for the majority of lung cancer patients and new strategies are urgently needed. In recent years, the concept of synthetic lethality has been established as an effective approach for discovering novel cancer-specific targets as well as a method to improve the efficacy of existing drugs which provide partial but insufficient benefits for patients. In this review, we discuss the concept of synthetic lethality, the various types of synthetic lethal interactions in the context of oncology and the approaches used to identify these interactions, including recent advances that have transformed the ability to discover novel synthetic lethal combinations on a global scale. Lastly, we describe the specific synthetic lethal interactions identified in lung cancer to date and explore the pharmacological challenges and considerations in translating these discoveries to the clinic.
A liposomal formulation of irinotecan, Irinophore C™ (IrC™) is efficacious in a panel of tumor models, normalizes tumor vasculature, and increases the accumulation of a second drug in the same tumor. ...We now show that Irinophore C™ is also effective against patient derived xenografts (PDX) of colon cancer, and examine the kinetics of vascular normalization in the HT-29 tumor model and assess how these changes might be used with 5-FU sequentially.
Rag2M mice bearing HT-29 tumors were treated with IrC™ (25mg/kg; Q7D×3) for up to three weeks. Groups of tumors were harvested for analysis at 7, 14 and 21days after the start of treatment. Drug and lipid levels in the tumor were evaluated using HPLC and scintillation counts, respectively. Changes in tumor morphology (H&E), vasculature (CD31), perfusion (Hoechst 33342) and apoptosis (TUNEL) were quantified using microscopy. The accumulation of a second drug (14C-5-FU, 40mg/kg) given 3h before sacrifice was determined using liquid scintillation. The efficacy of IrC™ (Q7D×3) followed by 5-FU treatment (Q7D×3) was assessed in mice bearing established HT-29 tumors. The efficacy of IrC™ was also evaluated in primary human colorectal tumors grown orthotopically in NOD-SCID mice.
Following a single dose of IrC™ the active lactone forms of irinotecan and its metabolite SN-38 were measurable in HT-29 tumors after 7days. The treatment reduced tumor cell density and increased apoptosis. Hoechst 33342 perfusion and accumulation of 14C-5-FU in the treated tumors increased significantly on days 7 and 14. This was accompanied by an increase in the number of endothelial cells relative to total nuclei in the tumor sections. Pre-treatment with IrC™ (Q7D×3) followed by 5-FU (Q7D×3) delayed the time taken for tumors to reach 1cm3 by 9days (p<0.05). IrC™ was just as effective as free irinotecan when used on patient derived xenografts of colorectal cancer.
Treatment with IrC™ reduces tumor cell viability and appears to normalize the vascular function of the tumor after a single treatment cycle. A concomitant increase in the accumulation of a second drug (5-FU) in the tumor was observed in tumors from IrC™ treated animals and this was correlated with changes in vascular structure consistent with normalization. The treatment effects of sequential 5-FU dosing following IrC™ are additive with no additional toxicity in contrast to previous studies where concurrent 5-FU and IrC™ treatment exacerbated 5-FU toxicity. The studies with PDX tumors also indicate that IrC™ is just as effective as free irinotecan on PDX tumors even though the delivered dose is halved.
Irinophore C™ (IrC™), extends the bioavailability of the active form of irinotecan, is more efficacious, and has little systematic toxicity. Cancer cells in primary orthotopic colon cancer tumors are obliterated with 6cycles of IrC™ treatment (H&E sections). Display omitted
A small molecule inhibitor (QLT0267) targeting integrin-linked kinase is able to slow breast tumor growth in vivo; however, the mechanism of action remains unknown. Understanding how targeting ...molecules involved in intersecting signaling pathways impact disease is challenging. To facilitate this understanding, we used tumor tissue microarrays (TMA) and digital image analysis for quantification of immunohistochemistry (IHC) in order to investigate how QLT0267 affects signaling pathways in an orthotopic model of breast cancer over time. Female NCR nude mice were inoculated with luciferase-positive human breast tumor cells (LCC6Luc) and tumor growth was assessed by bioluminescent imaging (BLI). The plasma levels of QLT0267 were determined by LC-MS/MS methods following oral dosing of QLT0267 (200 mg/kg). A TMA was constructed using tumor tissue collected at 2, 4, 6, 24, 78 and 168 hr after treatment. IHC methods were used to assess changes in ILK-related signaling. The TMA was digitized, and Aperio ScanScope and ImageScope software were used to provide semi-quantitative assessments of staining levels. Using medium-throughput IHC quantitation, we show that ILK targeting by QLT0267 in vivo influences tumor physiology through transient changes in pathways involving AKT, GSK-3 and TWIST accompanied by the translocation of the pro-apoptotic protein BAD and an increase in Caspase-3 activity.
Low aqueous solubility is a major barrier to the clinical application of otherwise promising drug candidates. We demonstrate that this issue can be resolved in medicinal molecules containing ...potential ligating groups, through the addition of labile transition‐metal ions. Incubation of the chemotherapeutic CX5461 with Cu2+ or Zn2+ enables solubilization at neutral pH but does not affect intrinsic cytotoxicity. Spectroscopic and computational studies demonstrate that this arises from coordination to the pyrazine functionality of CX5461 and may involve bidentate coordination at physiological pH.
Overcoming insolubility: A new method for solubilizing a hydrophobic drug while maintaining its intrinsic activity is demonstrated, using transition‐metal–ion interactions with ligating functional groups.
Clioquinol (CQ) is an FDA-approved topical antifungal agent known to kill cancer cells. This facilitated the initiation of clinical trials in patients with refractory hematologic malignancies. These ...repurposing efforts were not successful; this was likely due to low intracellular levels of the drug owing to poor absorption and rapid metabolism upon oral administration. CQ forms a sparingly soluble copper complex (Cu(CQ)
2
) that exhibits enhanced anticancer activity in some cell lines. We have utilized a novel method to synthesize Cu(CQ)
2
inside liposomes, an approach that maintains the complex suspended in solution and in a format suitable for intravenous administration. The complex was prepared inside 100-nm liposomes composed of 1,2-distearoyl-sn-glycero-3-phosphocholine/cholesterol (55:45). The therapeutic activity of the resultant formulation was evaluated in two subcutaneous tumor models (glioblastoma and ovarian cancers) but was not active. We also assessed the ability of the Cu(CQ)
2
formulation to increase copper delivery to cancer cells in vitro and its potential to be used in combination with disulfiram (DSF). The results suggested that addition of Cu(CQ)
2
enhanced cellular copper levels and the activity of DSF in vitro; however, this combination did not result in a statistically significant reduction in tumor growth in vivo. These studies demonstrate that a Cu(CQ)
2
formulation suitable for intravenous use can be prepared, but this formulation used alone or in combination with DSF was not efficacious. The methods described are suitable for development formulations of other analogues of 8-hydroxyquinoline which could prove to be more potent.
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