Thomas D Hart

The Role of Oncolytic Viruses in the Treatment of Melanoma

Purpose of ReviewOncolytic virotherapy is a new approach to the treatment of cancer and its success in the treatment of melanoma represents a breakthrough in cancer therapeutics. This paper provides a review of the current literature on the use of oncolytic viruses (OVs) in the treatment of melanoma.Recent FindingsTalimogene laherparepvec (T-VEC) is the first OV approved for the treatment of melanoma and presents new challenges as it enters the clinical setting. Several other OVs are at various stages of clinical and pre-clinical development for the treatment of melanoma. Reports from phase Ib-III clinical trials combining T-VEC with checkpoint blockade are encouraging and demonstrate potential added benefit of combination immunotherapy.SummaryOVs have recently emerged as a standard treatment option for patients with advanced melanoma. Several OVs and therapeutic combinations are in development. Immunooncolytic virotherapy combined with immune checkpoint inhibitors is promising for the treatment of advanced melanoma.

Quantitative Analysis of Immune Infiltrates in Primary Melanoma

Quantitative multiplex immunofluorescence and quantitative spatial analysis were used to evaluate the tumor microenvironment and allowed for the identification of a biomarker that correlated with survival in melanoma—the cytotoxic T lymphocyte-to-macrophage ratio. Novel methods to analyze the tumor microenvironment (TME) are urgently needed to stratify melanoma patients for adjuvant immunotherapy. Tumor-infiltrating lymphocyte (TIL) analysis, by conventional pathologic methods, is predictive but is insufficiently precise for clinical application. Quantitative multiplex immunofluorescence (qmIF) allows for evaluation of the TME using multiparameter phenotyping, tissue segmentation, and quantitative spatial analysis (qSA). Given that CD3+CD8+ cytotoxic lymphocytes (CTLs) promote antitumor immunity, whereas CD68+ macrophages impair immunity, we hypothesized that quantification and spatial analysis of macrophages and CTLs would correlate with clinical outcome. We applied qmIF to 104 primary stage II to III melanoma tumors and found that CTLs were closer in proximity to activated (CD68+HLA-DR+) macrophages than nonactivated (CD68+HLA-DR−) macrophages (P < 0.0001). CTLs were further in proximity from proliferating SOX10+ melanoma cells than nonproliferating ones (P < 0.0001). In 64 patients with known cause of death, we found that high CTL and low macrophage density in the stroma (P = 0.0038 and P = 0.0006, respectively) correlated with disease-specific survival (DSS), but the correlation was less significant for CTL and macrophage density in the tumor (P = 0.0147 and P = 0.0426, respectively). DSS correlation was strongest for stromal HLA-DR+ CTLs (P = 0.0005). CTL distance to HLA-DR− macrophages associated with poor DSS (P = 0.0016), whereas distance to Ki67− tumor cells associated inversely with DSS (P = 0.0006). A low CTL/macrophage ratio in the stroma conferred a hazard ratio (HR) of 3.719 for death from melanoma and correlated with shortened overall survival (OS) in the complete 104 patient cohort by Cox analysis (P = 0.009) and merits further development as a biomarker for clinical application. Cancer Immunol Res; 6(4); 481–93. ©2018 AACR.

Abstract P5-03-03: Cytotoxic t-lymphocyte density increased within the tumor immune microenvironment of patients with breast cancer following treatment with Akt inhibitor MK-2206

Background: The PAM (PI3K/Akt/mTOR) signaling pathway has been implicated in the oncogenesis of multiple solid malignancies, including breast cancer (BC). Tumor infiltrating lymphocytes (TILs) found within the tumor immune microenvironment (TME) are both prognostic of overall survival as well as predictive of response to neoadjuvant chemotherapy in BC. Our aim is to characterize the TME in a series of patients with operable stage I-III BC treated with MK-2206, an allosteric Akt inhibitor as part of a presurgical, window of opportunity, trial. In our presurgical trial (clinicaltrials.gov #: NCT01319539), patients received 2 doses of MK-2206 with first dose at day -9 and second at day -2 from surgery. Methods: Quantitative multiplex immunofluorescence (qmIF) was performed using immune biomarkers (DAPI, CD3, CD8, CD4, FOXP3, CD68, Pancytokeratin) on full section (4uM) tissue slides from core biopsy specimens and postsurgical specimens of 10 patients - 5 patient treated with MK-2206, and 5 prospectively collected untreated controls. Images were taken using Vectra, a novel pathology workstation and analyzed using inForm software to perform cell classification and phenotyping. Student T- test was used to compare biomarker changes before and after MK-2206. Results: Preliminary analysis demonstrates that patients treated with MK-2206 exhibited a significantly increased median cytotoxic T-cells (CD3CD8+) density, as compared to the matched control cohort (87% vs.0.2%, p Citation Format: Marks DK, Gartrell RD, Asmar ME, Hart TD, Lu Y, Esancy CL, Hibshoosh H, Connolly EP, Kalinsky KM, Saenger YM. Cytotoxic t-lymphocyte density increased within the tumor immune microenvironment of patients with breast cancer following treatment with Akt inhibitor MK-2206 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-03-03.