Sherif S. Morgan

Treatment of Unresectable and Metastatic Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (SCC) is an already common disorder with a rapidly increasing incidence. Treatment of early disease depends primarily on surgery or destructive techniques. In contrast to the frequency of early SCC, unresectable or metastatic SCC is relatively rare, but potentially life-threatening without clearly proven treatment options. Few rigorous studies of the treatment of advanced SCC have been undertaken. In the past, various agents have been explored in a limited fashion, including chemotherapy (cisplatin, fluoropyrimidines, bleomycin, doxorubicin), 13-cis-retinoic acid, and interferon-α2a. Clinical activity has been suggested by these trials, but their small sizes, heterogeneous patient populations, and lack of randomization have hindered the use of their results in defining treatment paradigms. Only one rigorous randomized trial has focused on cutaneous SCC. Enrolling 66 patients, that trial randomized patients at high recurrence risk to either observation or postoperative interferon-α2a and 13-cis-retinoic acid. This treatment did not improve time to recurrence or prevent secondary cutaneous SCC from developing. Though not in the metastatic setting, this study casts doubt on the ability of this regimen to control metastatic disease. Recently, agents targeting the human epidermal growth factor receptor (erlotinib, gefitinib, cetuximab) have displayed preliminary evidence of activity in phase II clinical trials and case series reports. Expression of this receptor is frequent in cutaneous SCC and appears to be prognostically adverse. Only the conduct of rigorous trials, with well-defined endpoints, adequate patient numbers, and preferably randomization, can prove the clinical efficacy of this promising treatment approach and define better therapy for this vexing clinical problem.

Thermostability of firefly luciferases affects efficiency of detection by in vivo bioluminescence.

Luciferase from the North American firefly (Photinis pyralis) is a useful reporter gene in vivo, allowing noninvasive imaging of tumor growth, metastasis, gene transfer, drug treatment, and gene expression. Luciferase is heat labile with an in vitro halflife of approximately 3 min at 37 degrees C. We have characterized wild type and six thermostabilized mutant luciferases. In vitro, mutants showed half-lives between 2- and 25-fold higher than wild type. Luciferase transfected mammalian cells were used to determine in vivo half-lives following cycloheximide inhibition of de novo protein synthesis. This showed increased in vivo thermostability in both wild-type and mutant luciferases. This may be due to a variety of factors, including chaperone activity, as steady-state luciferase levels were reduced by geldanamycin, an Hsp90 inhibitor. Mice inoculated with tumor cells stably transfected with mutant or wild-type luciferases were imaged. Increased light production and sensitivity were observed in the tumors bearing thermostable luciferase. Thermostable proteins increase imaging sensitivity. Presumably, as more active protein accumulates, detection is possible from a smaller number of mutant transfected cells compared to wild-type transfected cells.

Roles for Endothelin Receptor B and BCL2A1 in Spontaneous CNS Metastasis of Melanoma

Metastatic spread of melanoma to the central nervous system (CNS) is a common and devastating manifestation of disease progression, which, despite its clinical importance, remains poorly understood with respect to underlying molecular mechanisms. Using a recently developed preclinical model of spontaneous melanoma CNS metastasis, we have identified alterations in expression of endothelin receptor B (EDNRB) as a potential factor that influences brain metastatic potential. Induced overexpression of this gene mediated enhanced overall metastatic disease, and resulted in an increased incidence of spontaneous CNS metastases. In contrast, the overexpression of other highlighted genes, such as BCL2A1, did not affect the incidence of CNS metastases but nevertheless appears to facilitate intracranial tumor growth. The prometastatic effect in the CNS associated with EDNRB appears to be mediated by the interaction with its ligands resulting in enhanced tumor cell proliferation and thus intracranial melanoma growth. That EDNRB contributes to melanoma metastasis is underscored by the fact that its therapeutic inhibition by the EDNRB-specific inhibitor A192621 translated into improved outcomes when treating mice with either visceral metastases or intracranial tumors. The identification of an influential role of EDNRB in CNS melanoma spontaneous metastasis may provide both a target for therapeutic intervention as well as a potential prognostic marker for patients having an increased predisposition for incidence of CNS melanoma metastases.

Quantitative histopathology identifies patients with thin melanomas who are at risk for metastases.

This small exploratory study was designed to test the hypothesis that thin melanoma lesions contain nuclei of two similar phenotypes, in different proportions. In lesions likely to progress to metastatic disease, one of these phenotypes predominates. Histopathological sections from 18 cases of thin melanomas which did not progress to metastasis, and from 10 cases which did progress were imaged and digitized at high resolution, with a total of 2084 and 1148 nuclei, respectively, recorded. Five karyometric features were used to discriminate between nuclei from indolent and from potentially metastatic lesions. For each case, the percentage of nuclei classified by the discriminant function as having come from a potentially metastatic lesion was determined and termed as case classification criterion. Standard histopathological criteria, such as ulceration and high mitotic index, indicated in this material the need for intensive therapy for only one of the 10 participants, as compared with 7/10 identified correctly by the karyometric measure. Using a case classification criterion threshold of 40%, the overall accuracy was 86% in the test set. The proportion of nuclei of an aggressive phenotype may lend itself as an effective prognostic clue for thin melanoma lesions. The algorithm developed in this training set appears to identify those patients at high risk for metastatic disease, and demonstrates a basis for a further study to assess the utility of prognostic clues for thin melanomas.

Whole-brain radiation therapy in melanoma: an open question

However, we must disagree with their recommendations regarding melanoma patients. They suggest that “for the so-called radioresistant brain metastases from melanoma, renalcell carcinoma and sarcoma, it might be even more justifi ed to omit WBRT for one to three brain metastases, as it is thought that WBRT is less eff ective in this setting.” Their data do not support this recommendation. Like many brain metastasis studies, this study focuses on non-small-cell lung cancer (55% of patients). Only seven patients (12%) with melanoma were enrolled. A reference cited to support this recommendation, by the same group, was a retrospective study of SRS in patients with melanoma, sarcoma, and renal-cell carcinoma.

Abstract 2820: Vorinostat abrogates ridaforolimus-induced activation of Akt in synovial sarcoma cells: A possible rationale for their synergism

Background: Curative treatments for patients with metastatic synovial sarcoma (SS) do not exist and such patients have a poor prognosis. Previously, we demonstrated that the combination of the mTOR inhibitor ridaforolimus and the HDAC inhibitor vorinostat exhibited synergism in a variety of cell lines. Here, we explore whether the Akt pathway is potentially involved in mediating the synergistic effects of ridaforolimus and vorinostat. Methods: Two SS cell lines (HS-SY-II and SYO-I) were treated with the single agents or with combinations of ridaforolimus and vorinostat. After 72 hours, cell viability was measured using the cell proliferation assay (MTS). Combination Indices (CI) were calculated to determine whether each combination was synergistic, additive, or antagonistic. Western Blot analysis assessed alterations in total and phospho-Akt protein levels in response to drug treatment. Results: Ridaforolimus IC50 was 10.9nM in HS-SY-II and 23.1nM in SYO-I; vorinostat IC50 was 440nM in HS-SY-II and 561nM in SYO-I. CI were 0.28 and 0.63 in HS-SY-II and SYO-I, respectively, indicating synergism between the two agents. The ridaforolimus/vorinostat combination was assessed in other tumor types, including osteosarcoma (U2OS), metastatic melanoma (Stew1 and Stew2), pancreatic cancer (Panc1 and BxPC3), and lung cancer (A549). The combination was synergistic in all cell lines: CI ranged from 0.37 to 0.77, except in Panc1, where it was additive (CI=0.92). As previously observed with other mTOR inhibitors, ridaforolimus alone increased pAkt-ser473 levels in SS cell lines; this effect was abrogated by the addition of vorinostat. Conclusions: The combination of ridaforolimus and vorinostat demonstrates in vitro synergism in SS as well as in a variety of other tumor types. The addition of vorinostat prevented ridaforolimus-induced Akt activation, a possible mechanism of resistance to mTOR inhibition. Adding HDAC inhibition to mTOR inhibitors may be a route to circumvent Akt-mediated resistance to mTOR inhibitors. Our results also indicate that this combination may demonstrate broad anti-neoplastic activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2820. doi:1538-7445.AM2012-2820

Abstract A242: A novel AKT inhibitor, PH427, prevents UVB-induced signaling in human squamous skin carcinomas.

Non-melanoma skin cancers (NMSC) are a significant and increasing health problem in the United States that occur primarily on sun-exposed areas of the body and are strongly associated with chronic sun exposure. Recent advances in our understanding of the molecular basis of carcinogenesis have lead to the identification of potential molecular targets that might be used to prevent the progression of early skin cancer. AKT (protein kinase B), a pleckstrin homology (PH) lipid binding domain and a serine/threonine kinase containing protein is a key component of the phophatidylinositol-3-kinase (PtdIns3-K) cell survival signaling pathway which is activated in skin cancers. In this study, we describe the effects of a novel inhibitor of AKT (PH427) that binds to the PH domain of AKT thus preventing its binding to PtIns-(3,4,5)P3 at the plasma membrane and subsequent activation. PH427 inhibits AKT activity at low micromolar concentrations in HaCat human keratinocytes and HaCat-II,4, a ras transformed human keratinocyte cell line. We demonstrate that PH427 is able to prevent UVB-induced AKT activation and expression in both cell lines. PH427 also induced apoptosis in both HaCat and HaCat II,4 keratinocytes. Moreover, the compound is lipophilic and penetrates the skin in SKH-1 mice when applied topically. Short term in vitro studies showed that PH427 prevents UVB-induced AKT activation and UVB-induced signaling, as measured by p70S6 Kinase and p-GSK3-activation. Long-term in vivo studies utilizing SKH-1 mice have also shown significant reduction of UVB-induced skin tumors when PH427 is topically applied when compared to acetone-only control or PH427 alone. Additionally, drug treated mice exhibit reduced levels of phospho-Ser473AKT in the epidermal layers. We conclude that the topical application of PH427 may be beneficial for preventing NMSC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A242.

Retrospective analysis of nanoparticle albumin-encapsulated paclitaxel versus dacarbazine in advanced melanoma.

e19002 Background: Despite limited activity, dacarbazine (D) remains standard treatment for metastatic melanoma. Nanoparticle albumin-encapsulated-paclitaxel (nab-p; Abraxane) has demonstrated prom...