Moving Synergistically Acting Drug Combinations to the Clinic by Comparing Sequential versus Simultaneous Drug Administrations.

Drug combinations acting synergistically to kill cancer cells have become increasingly important in melanoma as an approach to manage the recurrent resistant disease. Protein kinase B (AKT) is a major target in this disease but its inhibitors are not effective clinically, which is a major concern. Targeting AKT in combination with WEE1 (mitotic inhibitor kinase) seems to have potential to make AKT-based therapeutics effective clinically. Since agents targeting AKT and WEE1 have been tested individually in the clinic, the quickest way to move the drug combination to patients would be to combine these agents sequentially, enabling the use of existing phase I clinical trial toxicity data. Therefore, a rapid preclinical approach is needed to evaluate whether simultaneous or sequential drug treatment has maximal therapeutic efficacy, which is based on a mechanistic rationale. To develop this approach, melanoma cell lines were treated with AKT inhibitor AZD5363 [4-amino-N-[(1S)-1-(4-chlorophenyl)-3-hydroxypropyl]-1-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)piperidine-4-carboxamide] and WEE1 inhibitor AZD1775 [2-allyl-1-(6-(2-hydroxypropan-2-yl)pyridin-2-yl)-6-((4-(4-methylpiperazin-1-yl)phenyl)amino)-1H-pyrazolo[3,4-d]pyrimidin-3(2H)-one] using simultaneous and sequential dosing schedules. Simultaneous treatment synergistically reduced melanoma cell survival and tumor growth. In contrast, sequential treatment was antagonistic and had a minimal tumor inhibitory effect compared with individual agents. Mechanistically, simultaneous targeting of AKT and WEE1 enhanced deregulation of the cell cycle and DNA damage repair pathways by modulating transcription factors p53 and forkhead box M1, which was not observed with sequential treatment. Thus, this study identifies a rapid approach to assess the drug combinations with a mechanistic basis for selection, which suggests that combining AKT and WEE1 inhibitors is needed for maximal efficacy.

Modulating cancer cell survival by targeting intracellular cholesterol transport.

BACKGROUND: Demand for cholesterol is high in certain cancers making them potentially sensitive to therapeutic strategies targeting cellular cholesterol homoeostasis. A potential approach involves disruption of intracellular cholesterol transport, which occurs in Niemann-Pick disease as a result of acid sphingomyelinase (ASM) deficiency. Hence, a class of lysosomotropic compounds that were identified as functional ASM inhibitors (FIASMAs) might exhibit chemotherapeutic activity by disrupting cancer cell cholesterol homoeostasis. METHODS: Here, the chemotherapeutic utility of ASM inhibition was investigated. The effect of FIASMAs on intracellular cholesterol levels, cholesterol homoeostasis, cellular endocytosis and signalling cascades were investigated. The in vivo efficacy of ASM inhibition was demonstrated using melanoma xenografts and a nanoparticle formulation was developed to overcome dose-limiting CNS-associated side effects of certain FIASMAs. RESULTS: Functional ASM inhibitors inhibited intracellular cholesterol transport leading to disruption of autophagic flux, cellular endocytosis and receptor tyrosine kinase signalling. Consequently, major oncogenic signalling cascades on which cancer cells were reliant for survival were inhibited. Two tested ASM inhibitors, perphenazine and fluphenazine that are also clinically used as antipsychotics, were effective in inhibiting xenografted tumour growth. Nanoliposomal encapsulation of the perphenazine enhanced its chemotherapeutic efficacy while decreasing CNS-associated side effects. CONCLUSIONS: This study suggests that disruption of intracellular cholesterol transport by targeting ASM could be utilised as a potential chemotherapeutic approach for treating cancer.

Plasmablastic Lymphoma Found on Autopsy in a Post-Transplant Patient.

Plasmablastic lymphoma (PBL) is an aggressive lymphoma often seen in immunodeficient patients. It can be a diagnostic challenge given its high-grade appearance and lack of staining for traditional B-cell markers. We present an interesting case of a 65-year-old African-American female who presented to the emergency department (ED) with complaints of progressively worsening weakness, fatigue, and dizziness for one month, and dark-colored urine for three days. The patient's medical history was remarkable for a renal and pancreatic transplant in 2008.

Spindle Cell Carcinoma of the Lung/Pleura: An Incidental Finding.

A 59-year-old male with a medical history of abdominal aortic dissection underwent a follow-up computed tomography (CT) scan abdomen, which showed an incidental pleural-based mass in the left lung base. The patient underwent an ultrasound (US)-guided biopsy and the histology was consistent with spindle cell carcinoma (SpCC). Staging workup was concerning for a metastatic lesion on the adrenal gland. The patient refused surgery and was subsequently started on chemotherapy. SpCC is a rare histological variant of sarcomatoid carcinoma. The prognosis is generally poor and treatment is the same as for other non-small cell lung cancers (NSCLC). The literature on disease progression and treatment is limited.

Identification of WEE1 as a target to make AKT inhibition more effective in melanoma.

AKT3 is one of the major therapeutic targets in melanoma but clinically targeting AKT3 alone seems to be an ineffective therapeutic approach. To identify unique strategies to enhance the efficacy of targeting AKT3, a screen was undertaken where AKT3 was co-targeted with a panel of kinases important in melanoma development. The screen identified WEE1 as the most potent target that when inhibited along with AKT3 would enhance the efficacy of targeting AKT3 in melanoma. RNAi mediated inhibition of AKT3 and WEE1 synergistically inhibited the viability of melanoma cells leading to a 65-75% decrease in tumor development. This approach was effective by mechanistically modulating pathways associated with the transcription factors p53 and FOXM1. Simultaneously regulating the activity of these two transcriptionally driven pathways, cooperatively deregulated cell cycle control and DNA damage repair to synergistically kill melanoma cells. This study uniquely identifies a potential approach to improve the efficacy of targeting AKT3 in melanoma.

Improving pharmacological targeting of AKT in melanoma.

Targeting AKT with pharmacological agents inhibiting this protein in the melanoma clinic is ineffective. This is a major contradiction considering the substantial preclinical data suggesting AKT as an effective target. Various approaches have been undertaken to unravel this contradiction and drug combinations sought that could resolve this concern. We have shown that genetic targeting AKT3 or WEE1 can be effective for inhibiting tumor growth in preclinical animal models. However, no one has examined whether combining pharmacological agents targeting each of these enzymes could be more effective than inhibiting each alone and enhance the efficacy of targeting AKT in melanoma. This report shows that combining the AKT inhibitors (AZD5363 or MK1775) with the WEE1 inhibitor, AZD5363, can synergistically kill cultured melanoma cells and decrease melanoma tumor growth by greater than 90%. Co-targeting AKT and WEE1 led to enhanced deregulation of the cell cycle and DNA damage repair pathways by modulating the transcription factors p53 and FOXM1, as well as the proteins whose expression is regulated by these two proteins. Thus, this study identifies a unique combination of pharmacological agents and the ratio needed for efficacy that could be used to potentially improve the therapeutic effectiveness of targeting AKT in the clinic.

The Role of Cholesterol in Cancer.

The roles played by cholesterol in cancer development and the potential of therapeutically targeting cholesterol homeostasis is a controversial area in the cancer community. Several epidemiologic studies report an association between cancer and serum cholesterol levels or statin use, while others suggest that there is not one. Furthermore, the Cancer Genome Atlas (TCGA) project using next-generation sequencing has profiled the mutational status and expression levels of all the genes in diverse cancers, including those involved in cholesterol metabolism, providing correlative support for a role of the cholesterol pathway in cancer development. Finally, preclinical studies tend to more consistently support the role of cholesterol in cancer, with several demonstrating that cholesterol homeostasis genes can modulate development. Because of space limitations, this review provides selected examples of the epidemiologic, TCGA, and preclinical data, focusing on alterations in cholesterol homeostasis and its consequent effect on patient survival. In melanoma, this focused analysis demonstrated that enhanced expression of cholesterol synthesis genes was associated with decreased patient survival. Collectively, the studies in melanoma and other cancer types suggested a potential role of disrupted cholesterol homeostasis in cancer development but additional studies are needed to link population-based epidemiological data, the TCGA database results, and preclinical mechanistic evidence to concretely resolve this controversy. Cancer Res; 76(8); 2063-70. ©2016 AACR.

Current State of Animal (Mouse) Modeling in Melanoma Research.

Despite the considerable progress in understanding the biology of human cancer and technological advancement in drug discovery, treatment failure remains an inevitable outcome for most cancer patients with advanced diseases, including melanoma. Despite FDA-approved BRAF-targeted therapies for advanced stage melanoma showed a great deal of promise, development of rapid resistance limits the success. Hence, the overall success rate of melanoma therapy still remains to be one of the worst compared to other malignancies. Advancement of next-generation sequencing technology allowed better identification of alterations that trigger melanoma development. As development of successful therapies strongly depends on clinically relevant preclinical models, together with the new findings, more advanced melanoma models have been generated. In this article, besides traditional mouse models of melanoma, we will discuss recent ones, such as patient-derived tumor xenografts, topically inducible BRAF mouse model and RCAS/TVA-based model, and their advantages as well as limitations. Although mouse models of melanoma are often criticized as poor predictors of whether an experimental drug would be an effective treatment, development of new and more relevant models could circumvent this problem in the near future.