Zoe Blake

Talimogene laherparepvec (T-Vec) for the treatment of melanoma and other cancers

Talimogene laherparepvec (T-Vec) is the first live virus to be approved by the US Food and Drug Administration for the treatment of cancer. This engineered version of herpes simplex virus type 1 (HSV-1) is the product of decades of preclinical work aimed at identifying and modifying aspects of the viral genome involved in virulence and immunogenicity. T-Vec preferentially infects and lyses tumor cells and, in some cases, induces a systemic immune response against the tumor. These properties have translated into significant and durable clinical responses, particularly in advanced melanoma. Many unanswered questions remain, including how to augment these clinical responses and which other tumor types may respond to oncolytic therapy. Here, we review the development of T-Vec, our current understanding of its impact on the tumor immune micro-environment, and its safety and efficacy in clinical trials for melanoma and other cancers.

Complete intracranial response to talimogene laherparepvec (T-Vec), pembrolizumab and whole brain radiotherapy in a patient with melanoma brain metastases refractory to dual checkpoint-inhibition

BackgroundImmunotherapy, in particular checkpoint blockade, has changed the clinical landscape of metastatic melanoma. Nonetheless, the majority of patients will either be primary refractory or progress over follow up. Management of patients progressing on first-line immunotherapy remains challenging. Expanded treatment options with combination immunotherapy has demonstrated efficacy in patients previously unresponsive to single agent or alternative combination therapy.Case presentationWe describe the case of a patient with diffusely metastatic melanoma, including brain metastases, who, despite being treated with stereotactic radiosurgery and dual CTLA-4/PD-1 blockade (ipilimumab/nivolumab), developed systemic disease progression and innumerable brain metastases. This patient achieved a complete CNS response and partial systemic response with standard whole brain radiation therapy (WBRT) combined with Talimogene laherparepvec (T-Vec) and pembrolizumab.ConclusionPatients who do not respond to one immunotherapy combination may respond during treatment with an alternate combination, even in the presence of multiple brain metastases. Biomarkers are needed to assist clinicians in evidence based clinical decision making after progression on first line immunotherapy to determine whether response can be achieved with second line immunotherapy.

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 A41: Combination immunotherapy leads to decreased tumor growth

Introduction/Background: Talimogene Laherparepvec (T-Vec) is the first oncolytic virus to be FDA approved for the treatment of cancer. T-Vec, a modified Herpes Simplex Type I virus (HSV I), has two mechanisms of action: direct cell lysis and immune activation. Combination immunotherapy using T-Vec and check-point blockade has shown promise in clinical trials.1 In preliminary work, our lab has shown that T-Vec causes up-regulation of programmed cell death protein 1 (PD-1) on infiltrating T cells in mice, suggesting potential synergy of T-Vec and anti-PD1 (α-PD1). The purpose of our study is to evaluate the effectiveness of combination immunotherapy to treat melanoma tumors in a transgenic BRAF melanoma model and study the immune microenvironment of these tumors post treatment. Materials and Methods: In a temporally and spatially regulated murine model of BRAFCA PTEN-/- spontaneous melanoma2, tumors are induced on the shaved right flank of mice. When tumors reach ≥5mm in diameter, mice are randomized into 6 treatment groups comparing combinations of BRAF inhibition (BRAFi) or control chow, intraperitoneal injections of α-PD1 or control (2A3), and intratumoral injections of T-Vec or control (PBS) by intratumoral injection. Treatment Groups: 1: Control + 2A3 + PBS 2: BRAFi + 2A3 + PBS 3: BRAFi + α-PD1 + PBS 4: BRAFi + 2A3 + T-Vec 5: BRAFi + α-PD1 + T-Vec 6: Control + α-PD1 + T-Vec Tumor growth is measured biweekly until end of study. Flow cytometry is performed on tumor, lymph node, and spleen to assess immune microenvironment. Multiplex immunohistochemistry will also be performed and analyzed with Mantra, using 6 immune biomarkers. Results: Mean tumor volume and survival was plotted to compare groups. Mice treated with combination T-Vec + BRAFi with or without α-PD1 have decreased tumor growth and longer survival compared to mice treated with control or single drug arms. Flow cytometry shows an increase in percent CD3+ cells in tumors of mice treated with combination α-PD1 + T-Vec compared to the control and single drug arms. Further analysis revealed very few CD45+ cells in tumors of the control group whilst mice receiving combination immunotherapy without BRAFi have higher CD45+ cells in tumor. Percent CD8+/CD3+ cells in tumors treated with immunotherapy appears to be increased compared to the control and BRAFi only group. Additionally, percent of CD4+/FOXP3+ cells in tumors appears to be decreased in groups receiving T-Vec while no change in CD4+/FOXP3+ populations was observed in draining lymph node or spleen. Conclusions: Initial findings show that combination therapy of BRAFi + α-PD1 + T-Vec is more effective than any single treatment. Combination immunotherapy increases infiltration of T cells into tumor. Furthermore, oncolytic virus appears to decrease CD4+/FOXP3+ (regulatory T cells) infiltrating tumor. This study is ongoing and further analysis will continue as we further evaluate the immune microenvironment using flow cytometry and immunohistochemistry. Acknowledgements: The study was funded by the Melanoma Research Alliance and Amgen (Amgen-CUMC-MRA Established Investigator Academic-Industry Partnership Award). References: 1. Andtbacka, R.H.I., et al. OPTiM: A randomized phase III trial of talimogene laherparepvec (T-VEC) versus subcutaneous (SC) granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment (tx) of unresected stage IIIB/C and IV melanoma. ASCO Meeting Abstracts 31, LBA9008 (2013). 2. Dankort, D., et al. Braf(V600E) cooperates with Pten loss to induce metastatic melanoma. Nature genetics 41, 544-552 (2009). Citation Format: Robyn Gartrell, Zoe Blake, Ines Simoes, Yichun Fu, Takuro Sato, Yingzhi Qian, James Zhang, Yan Lu, Yvonne Saenger. Combination immunotherapy leads to decreased tumor growth. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A41.