Personalized oncology and BRAFK601N melanoma: model development, drug discovery, and clinical correlation.

PURPOSE: Mutations in BRAF are the most prominent activating mutations in melanoma and are increasingly recognized in other cancers. There is currently no accepted treatment regimen for patients with mutant BRAFK601N melanoma, and the study of melanoma driven by BRAF mutations at the 601 locus is lacking due to a paucity of cellular model systems. Therefore, we sought to better understand the treatment and clinical approach to patients with mutant BRAFK601N melanoma and subsequently develop a novel personalized oncology platform for rare or treatment-refractory cancers. METHODS: We developed and characterized the first patient-derived, naturally occurring BRAFK601N melanoma model, described herein as OHRI-MEL-13, and assessed efficacy using the Prestwick Chemical Library and select targeted therapeutics. RESULTS: OHRI-MEL-13 exhibits loss of heterozygosity of BRAF, closely mimics the original tumor's gene expression profile, is tumorigenic in immune-deficient murine models, and is available for public accession through American Type Culture Collection. We present in silico modeling data, which illustrates the therapeutic failure of BRAFV600E-targeted therapies in BRAFK601N mutants. Our platform elucidated a unique role for MEK inhibition with cobimetinib, which resulted in short-term clinical success by reducing the metastatic burden. CONCLUSION: Our model of BRAFK601N-activated melanoma was developed, thoroughly characterized, and made available for public accession. This model served to demonstrate the feasibility of a novel personalized oncology platform that could be optimized at an institutional level for rare variant or treatment-refractory cancers. We also demonstrate the clinical utility of monotherapy MEK inhibition in a case of BRAFK601N melanoma.

Enhancing Expression of Functional Human Sodium Iodide Symporter and Somatostatin Receptor in Recombinant Oncolytic Vaccinia Virus for In Vivo Imaging of Tumors.

Oncolytic virus (OV) therapy has emerged as a novel tool in our therapeutic arsenals for fighting cancer. As a live biologic agent, OV has the ability to target and selectively amplify at the tumor sites. We have reported that a vaccinia-based OV (Pexa-Vec) has shown good efficacy in preclinical models and in clinical trials. To give an additional tool to clinicians to allow both treatment of the tumor and improved visualization of tumor margins, we developed new viral-based platforms with 2 specific gene reporters. METHODS: We incorporated the human sodium iodide symporter (hNIS) and the human somatostatin receptor 2 (hSSR2) in the vaccinia-based OV and tested viral constructs for their abilities to track and treat tumor development in vivo. RESULTS: Early and high-level expression of hNIS is detrimental to the recombinant virus, leading to the aggregation of hNIS protein and early cell death. Putting hNIS under a late synthetic promoter allowed a higher functional expression of the protein and much stronger 123I or 99Tc uptake. In vivo, the hNIS-containing virus infected and amplified in the tumor site, showing a better efficacy than the parental virus. The hNIS expression at the tumor site allowed for the imaging of viral infection and tumor regression. Similarly, hSSR2-containing OV vaccinia infected and lysed cancer cells. CONCLUSION: When tumor-bearing mice were given hNIS- and hSSR2-containing OV, 99Tc and 111In signals coalesced at the tumor, highlighting the power of using these viruses for tumor diagnosis and treatment.

Lovastatin enhances gefitinib activity in glioblastoma cells irrespective of EGFRvIII and PTEN status.

The epidermal growth factor receptor (EGFR) is commonly amplified and mutated in glioblastoma, making it a compelling therapeutic target. Recent reports have demonstrated clinical activity of the EGFR inhibitors gefitinib and erlotinib in a subset of glioblastoma patients. Co-expression of EGFRvIII, a constitutively active mutant receptor expressed in 50% of tumours, and PTEN, an inhibitor of PI3K activity, by glioblastoma cells is associated with clinical response to these EGFR kinase inhibitors. PTEN loss and resulting increased PI3K pathway activity appears to act as a resistance factor. A critical therapeutic challenge is to identify agents that enhance the anti-cancer effects of these agents and promote responsiveness to EGFR kinase inhibitors in a broader spectrum of glioblastoma patients. For example, combining gefitinib with inhibitors of the PI3K/AKT pathway show enhanced cytotoxicity in glioblastoma derived cell lines. Here, we show that targeting HMG-CoA reductase with lovastatin, that can affect the activity of multiple cell signaling pathways, significantly enhanced the sensitivity of glioblastoma cells to the EGFR kinase inhibitor gefitinib in the five cell lines tested. In an isogenic model system, U87MG glioblastoma cells expressing EGFRvIII and PTEN in relevant combinations, we show that combined gefitinib and lovastatin treatments induce potent synergistic cytotoxicity irrespective of EGFRvIII and PTEN status. These studies demonstrate the potential of lovastatin to augment the cytotoxic effects of gefitinib and provide a rationale for combined statin/EGFR targeted therapies in glioblastoma patients.

Recombinant bovine growth hormone-induced reduction of atrial natriuretic peptide is associated with improved left ventricular contractility and reverse remodeling in cardiomyopathic UM-X7.1 hamsters with congestive heart failure.

OBJECTIVE: To assess the effect of short-term treatment with GH on left ventricular contractility and remodeling, after the development of heart failure in cardiomyopathic hamsters (CMH). DESIGN: Two groups of 200-day-old UM-X7.1 CMH received daily subcutaneous injections of recombinant bovine (rb) GH (1mg/kg/day) or 0.9% NaCl for 40 days. Golden Syrian hamsters (GSH) were used as controls. At 240-day-old, the hamsters were randomly subjected to (i) assessment of left ventricular systolic function in a Langendorff perfused mode followed by the determination of the passive diastolic pressure-volume relationship and morphometric measurements; (ii) assessment of left ventricular mRNA expression of genes belonging to the fetal gene program including atrial (ANP) and brain (BNP) natriuretic peptides and cardiac myosin heavy chain isoforms and of the circulating levels of the natriuretic peptides. RESULTS: Hearts from CMH were hypertrophied and dilated (p<0.05) compared to hearts from GSH, along with a approximately 10-fold increase in the circulating ANP and BNP levels. Left ventricular BNP and ANP mRNAs were elevated by 2- and 3-fold, respectively, compared to GSH. rbGH reduced both ANP mRNA and ANP circulating levels by 34% (p<0.01) but did not significantly modulate BNP levels. This effect was associated with a preserved systolic function and reverse remodeling as assessed by a leftward shift of the passive diastolic pressure-volume relationship indicating reduced ventricular dilatation. CONCLUSIONS: The data show that a short-term administration of GH in the terminal phase of the disease confers cardioprotection by attenuating systolic dysfunction and by inducing beneficial reverse remodeling.

Effect of chronic treatment with bovine recombinant growth hormone on cardiac dysfunction and lesion progression in UM-X7.1 cardiomyopathic hamsters.

In view of the potentially beneficial effect of GH on ventricular function of humans suffering from idiopathic dilated cardiomyopathy, we undertook a study to evaluate the optimal time to initiate treatment with GH and its duration in UM-X7.1 cardiomyopathic hamsters (CMH). GH (1 mg/kg.d) therapy was initiated either in the early or late (30 and 160 d old, respectively) phases of the disease and continued until death at 240 d of age. Age- and sex-matched Golden Syrian hamsters (GSH) were used as controls. Basal IGF-1 levels in serum were reduced by nearly half in CMH compared with GSH but were increased within a physiological range in male hamsters. In contrast, female hamsters presented elevated basal serum IGF-1 levels that were not further elevated by GH administration, as reported in experimental models and humans. Accordingly, the present study will focus on the effects of GH therapy on cardiac performance in male hamsters. GH did not improve ventricular function when starting at a late stage of the disease compared with CMH controls. Maximum rate of left ventricular pressure development decreased by approximately 64% in CMH treated early with recombinant bovine GH. Ventricular dysfunction was associated with morphologic indices of hypertrophy, ventricular dilatation, and extensive fibrosis. Mortality was strikingly increased in GH-treated CMH for 210 d (four males and eight females), as opposed to four females (and no male) in the vehicle-treated group. These results suggest that chronic treatment with recombinant bovine GH in CMH, starting at an early stage of lesion development, is associated with a reduced cardiac performance at the terminal stage of the disease.