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Immune checkpoint blockade represents a major breakthrough in cancer therapy; however, responses are not universal. Genomic and immune features in pretreatment tumor biopsies have been reported to correlate with response in patients with melanoma and other cancers, but robust biomarkers have not been identified. We studied a cohort of patients with metastatic melanoma initially treated with cytotoxic T-lymphocyte–associated antigen-4 (CTLA4) blockade (n = 53) followed by programmed death-1 (PD-1) blockade at progression (n = 46), and analyzed immune signatures in longitudinal tissue samples collected at multiple time points during therapy. In this study, we demonstrate that adaptive immune signatures in tumor biopsy samples obtained early during the course of treatment are highly predictive of response to immune checkpoint blockade and also demonstrate differential effects on the tumor microenvironment induced by CTLA4 and PD-1 blockade. Importantly, potential mechanisms of therapeutic resistance to immune checkpoint blockade were also identified. Significance: These studies demonstrate that adaptive immune signatures in early on-treatment tumor biopsies are predictive of response to checkpoint blockade and yield insight into mechanisms of therapeutic resistance. These concepts have far-reaching implications in this age of precision medicine and should be explored in immune checkpoint blockade treatment across cancer types. Cancer Discov; 6(8); 827–37. ©2016 AACR. See related commentary by Teng et al., p. 818. This article is highlighted in the In This Issue feature, p. 803

BRAF inhibitor (BRAFi) treatment enhances antitumor immunity, but is associated with increased intratumoral PD-L1 expression. MEK inhibitors (MEKi) may alter T-cell function; however, recent studies demonstrate preserved T-cell infiltrate during treatment with BRAFi/MEKi. These data have important implications for combining BRAFi/MEKi and checkpoint blockade in the treatment of melanoma. Clin Cancer Res; 21(14); 3102–4. ©2015 AACR. See related article by Kakavand et al., p. 3140

Medical research for human benefit is greatly impeded by the necessity for human tissues and subjects. However, upon obtaining consent for human specimens, precious samples must be handled with the greatest care in order to ensure integrity of organs, tissues, and cells to the highest degree. Unfortunately, tissue processing by definition requires extraction of tissues from the host, a change which can cause great cellular stress and have major repercussions on subsequent analyses. These stresses could result in the specimen being no longer representative of the site from which it was retrieved. Therefore, a strict protocol must be adhered to while processing these specimens to ensure representativeness. The desired assay(s) must also be taken into consideration in order to ensure that an optimal technique is used for sample processing. Outlined here is a protocol for tissue retrieval, processing and various analyses which may be performed on processed tissue in order to maximize downstream production from limited tissue samples.

There have been significant advances in the treatment of metastatic melanoma through targeted and immunotherapy, however a significant proportion of patients still progress on these regimens with many experiencing mixed responses. Intense research efforts to better understand resistance are underway, and multiple molecular resistance mechanisms to targeted therapy have been identified. The appreciation of genetic heterogeneity as a contributor to resistance to therapy has grown, though immune heterogeneity has been poorly characterized. The goal of the present study is to better understand the molecular and immune heterogeneity in synchronous melanoma metastases at the time of disease progression. In this study, we prospectively evaluated 32 tumors from 15 patients who were treatment-naïve (n = 4), or had received prior targeted (n = 4) or immunotherapy (n = 7). Whole exome sequencing demonstrated between 4-41% of non-synonymous exonic mutations (NSEM) were restricted to individual tumors within a patient. Deep profiling of infiltrating immune cell subsets by flow cytometry and immunohistochemistry analyses confirmed the immune infiltrate between synchronous metastases to be highly heterogeneous, specifically in regards to CD4 and CD8 T lymphocytes. In aggregate, 92% of these T cell clones were unique to distinct tumors within the same patient, with limited overlap with clones detected in the blood. NetMHC3.4 neoantigen prediction demonstrated a large fraction of predicted neoantigens were restricted to individual tumors, with over 10% of these presenting extremely high predicted affinity. Importantly, analysis of RECIST measurements of individual lesions within the same patient suggested this molecular and immune heterogeneity could contribute to differential tumor growth and response to therapy within the same patient. This has important clinical implications, and suggests a single tumor biopsy may not be sufficiently representative of the molecular and immune landscape of multiple tumors within the same individual. Citation Format: Alexandre Reuben, Christine N. Spencer, Peter A. Prieto, John P. Miller, Xizeng Mao, Wei-Shen Chen, Hannah Cheung, Hong Jiang, Cara Haymaker, Mariana Petaccia De Macedo, Haven R. Garber, Pei-Ling Chen, Vancheswaran Gopalakrishnan, Jacob Austin-Breneman, Courtney W. Hudgens, Jason Roszik, Patrick Hwu, Scott E. Woodman, Lynda Chin, Michael A. Davies, Rodabe N. Amaria, Sapna P. Patel, Alexander J. Lazar, Michael T. Tetzlaff, Karen C. Dwyer, Ignacio I. Wistuba, Padmanee Sharma, James P. Allison, Jianhua Zhang, Andrew Futreal, Zachary A. Cooper, Jennifer A. Wargo. Genomic and immune heterogeneity in synchronous melanoma metastases is associated with differential tumor growth and response to therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2392.

We have made major advances in the treatment of melanoma through the use of targeted therapy and immune checkpoint blockade; however, clinicians are posed with therapeutic dilemmas regarding timing and sequence of therapy. There is a growing appreciation of the impact of antitumor immune responses to these therapies, and we performed studies to test the hypothesis that clinical patterns and immune infiltrates differ at progression on these treatments. We observed rapid clinical progression kinetics in patients on targeted therapy compared to immune checkpoint blockade. To gain insight into possible immune mechanisms behind these differences, we performed deep immune profiling in tumors of patients on therapy. We demonstrated low CD8+ T-cell infiltrate on targeted therapy and high CD8+ T-cell infiltrate on immune checkpoint blockade at clinical progression. These data have important implications, and suggest that antitumor immune responses should be assessed when considering therapeutic options for patients with melanoma.

There have been significant advances in the treatment of metastatic melanoma via the use of targeted and immunotherapy, however a significant proportion of patients still progress on treatment. Intense research efforts to better understand resistance are underway, and multiple molecular resistance mechanisms to targeted therapy have been identified. Appreciation of intratumoral genetic heterogeneity as a contributor to resistance to therapy is growing, although immune heterogeneity in multiple solid tumors within a same patient has been less well characterized. The goal of the present study is to better understand the leukocyte infiltrate in multiple melanoma tumors within the same patient at the time of disease progression, with the potential to identify actionable strategies to overcome resistance to therapy. In this study, we prospectively evaluated 8 tumors from 4 patients on either targeted or immunotherapy. Tissues were evaluated by polychromatic flow cytometry, complemented with immunohistochemical (IHC) analysis of tissue sections. Specifically, we utilized 5 distinct flow cytometry panels comprising 35 antibodies and an 11-marker IHC antibody panel to better understand the intratumoral leukocyte composition as well as presence of immune checkpoint molecules PD-1 and PD-L1. Results demonstrate significant immune heterogeneity between different melanoma tumors within the same patient in the majority of patients studied. Of note, there were significant differences in CD4+, CD8+, and regulatory T cells (p Citation Format: Alexandre Reuben, Zachary A. Cooper, Whijae Roh, Yu Cao, Jacob Austin-Breneman, Hong Jiang, Rodabe N. Amaria, Pei-Ling Chen, Michael T. Tetzlaff, Lynda Chin, Andrew Futreal, Michael A. Davies, Jennifer A. Wargo. Inter- and intra-tumoral immune and genomic heterogeneity in patients with metastatic melanoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1301. doi:10.1158/1538-7445.AM2015-1301

e20097 Background: Significant advances have been made in the treatment of stage IV melanoma through the use of targeted therapies in patients (pts) with BRAF V600 mutations. However, there is a cr...