Tricia R. Cottrell

Neoadjuvant PD-1 Blockade in Resectable Lung Cancer

BACKGROUND Antibodies that block programmed death 1 (PD‐1) protein improve survival in patients with advanced non–small‐cell lung cancer (NSCLC) but have not been tested in resectable NSCLC, a condition in which little progress has been made during the past decade. METHODS In this pilot study, we administered two preoperative doses of PD‐1 inhibitor nivolumab in adults with untreated, surgically resectable early (stage I, II, or IIIA) NSCLC. Nivolumab (at a dose of 3 mg per kilogram of body weight) was administered intravenously every 2 weeks, with surgery planned approximately 4 weeks after the first dose. The primary end points of the study were safety and feasibility. We also evaluated the tumor pathological response, expression of programmed death ligand 1 (PD‐L1), mutational burden, and mutation‐associated, neoantigen‐specific T‐cell responses. RESULTS Neoadjuvant nivolumab had an acceptable side‐effect profile and was not associated with delays in surgery. Of the 21 tumors that were removed, 20 were completely resected. A major pathological response occurred in 9 of 20 resected tumors (45%). Responses occurred in both PD‐L1–positive and PD‐L1–negative tumors. There was a significant correlation between the pathological response and the pretreatment tumor mutational burden. The number of T‐cell clones that were found in both the tumor and peripheral blood increased systemically after PD‐1 blockade in eight of nine patients who were evaluated. Mutation‐associated, neoantigen‐specific T‐cell clones from a primary tumor with a complete response on pathological assessment rapidly expanded in peripheral blood at 2 to 4 weeks after treatment; some of these clones were not detected before the administration of nivolumab. CONCLUSIONS Neoadjuvant nivolumab was associated with few side effects, did not delay surgery, and induced a major pathological response in 45% of resected tumors. The tumor mutational burden was predictive of the pathological response to PD‐1 blockade. Treatment induced expansion of mutation‐associated, neoantigen‐specific T‐cell clones in peripheral blood. (Funded by Cancer Research Institute–Stand Up 2 Cancer and others; ClinicalTrials.gov number, NCT02259621.)

PD-L1 Expression in Melanoma: A Quantitative Immunohistochemical Antibody Comparison

Purpose: PD-L1 expression in the pretreatment tumor microenvironment enriches for response to anti-PD-1/PD-L1 therapies. The purpose of this study was to quantitatively compare the performance of five monoclonal anti-PD-L1 antibodies used in recent landmark publications. Experimental Design: PD-L1 IHC was performed on 34 formalin-fixed paraffin-embedded archival melanoma samples using the 5H1, SP142, 28-8, 22C3, and SP263 clones. The percentage of total cells (including melanocytes and immune cells) demonstrating cell surface PD-L1 staining, as well as intensity measurements/H-scores, were assessed for each melanoma specimen using a computer-assisted platform. Staining properties were compared between antibodies. Results: Strong correlations were observed between the percentage of PD-L1(+) cells across all clones studied (R2 = 0.81–0.96). When present, discordant results were attributable to geographic heterogeneity of the melanoma tissue section rather than differences in PD-L1 antibody staining characteristics. PD-L1 intensity/H-scores strongly correlated with percentage of PD-L1(+) cells (R2 > 0.78, all clones). Conclusions: The 5H1, SP142, 28-8, 22C3, and SP263 clones all demonstrated similar performance characteristics when used in a standardized IHC assay on melanoma specimens. Reported differences in PD-L1 IHC assays using these antibodies are thus most likely due to assay characteristics beyond the antibody itself. Our findings also argue against the inclusion of an intensity/H-score in chromogenic PD-L1 IHC assays. Clin Cancer Res; 23(16); 4938–44. ©2017 AACR.

Implications of the tumor immune microenvironment for staging and therapeutics

Characterizing the tumor immune microenvironment enables the identification of new prognostic and predictive biomarkers, the development of novel therapeutic targets and strategies, and the possibility to guide first-line treatment algorithms. Although the driving elements within the tumor microenvironment of individual primary organ sites differ, many of the salient features remain the same. The presence of a robust antitumor milieu characterized by an abundance of CD8+ cytotoxic T-cells, Th1 helper cells, and associated cytokines often indicates a degree of tumor containment by the immune system and can even lead to tumor elimination. Some of these features have been combined into an ‘Immunoscore’, which has been shown to complement the prognostic ability of the current TNM staging for early stage colorectal carcinomas. Features of the immune microenvironment are also potential therapeutic targets, and immune checkpoint inhibitors targeting the PD-1/PD-L1 axis are especially promising. FDA-approved indications for anti-PD-1/PD-L1 are rapidly expanding across numerous tumor types and, in certain cases, are accompanied by companion or complimentary PD-L1 immunohistochemical diagnostics. Pathologists have direct visual access to tumor tissue and in-depth knowledge of the histological variations between and within tumor types and thus are poised to drive forward our understanding of the tumor microenvironment. This review summarizes the key components of the tumor microenvironment, presents an overview of and the challenges with PD-L1 antibodies and assays, and addresses newer candidate biomarkers, such as CD8+ cell density and mutational load. Characteristics of the local immune contexture and current pathology-related practices for specific tumor types are also addressed. In the future, characterization of the host antitumor immune response using multiplexed and multimodality biomarkers may help predict which patients will respond to immune-based therapies.

Melanoma subtypes demonstrate distinct PD-L1 expression profiles

PD-L1 expression in the tumor immune microenvironment is recognized as both a prognostic and predictive biomarker in patients with cutaneous melanoma, a finding closely related to its adaptive (IFN-γ-mediated) mechanism of expression. Approximately 35% of cutaneous melanomas express PD-L1, however, the expression patterns, levels, and prevalence in rarer melanoma subtypes are not well described. We performed immunohistochemistry for PD-L1 and CD8 on 200 formalin-fixed paraffin-embedded specimens from patients with acral (n=16), mucosal (n=36), uveal (n=103), and chronic sun-damaged (CSD) (n=45) melanomas (24 lentigo maligna, 13 mixed desmoplastic, and 8 pure desmoplastic melanomas). CD8+ tumor-infiltrating lymphocyte (TIL) densities were characterized as mild, moderate, or severe, and their geographic association with PD-L1 expression was evaluated. Discrete lymphoid aggregates, the presence of a spindle cell morphology, and the relationship of these features with PD-L1 expression were assessed. PD-L1 expression was observed in 31% of acral melanomas, 44% of mucosal melanomas, 10% of uveal melanomas, and 62% of CSD melanomas (P<0.0001). Compared to our previously characterized cohort of cutaneous melanomas, the proportion of PD-L1(+) tumors was lower in uveal (P=0.0002) and higher in CSD (P=0.0073) melanomas, while PD-L1 expression in the acral and mucosal subtypes was on par. PD-L1 expression in all subtypes correlated with a moderate-severe grade of CD8+ TIL (all, P<0.003), supporting an adaptive mechanism of expression induced during the host antitumor response. The tumor microenvironments observed in CSD melanomas segregated by whether they were the pure desmoplastic subtype, which showed lower levels of PD-L1 expression when compared to other CSD melanomas (P=0.047). The presence of lymphoid aggregates was not associated with the level of PD-L1 expression, while PD-L1(+) cases with spindle cell morphology demonstrated higher levels of PD-L1 than those with a nested phenotype (P<0.0001). Our findings may underpin the reported clinical response rates for anti-PD-1 monotherapy, which vary by subtype.

Identification of novel autoantigens by a triangulation approach

High titer autoantibodies, which are often associated with specific clinical phenotypes, are useful diagnostically and prognostically in systemic autoimmune diseases. In several autoimmune rheumatic diseases (e.g. myositis and Sjogrens syndrome), 20-40% of patients are autoantibody negative as assessed by conventional assays. The recent discovery of new specificities (e.g., anti-MDA5) in a subset of these autoantibody-negative subjects demonstrates that additional specificities await identification. In this manuscript, we describe a rapid multidimensional method to identify new autoantigens. A central foundation of this rapid approach is the use of an antigen source in which a pathogenic pathway active in the disease is recapitulated. Additionally, the method involves a modified serological proteome analysis strategy which allows confirmation that the correct gel plug has been removed prior to sending for sequencing. Lastly, the approach uses multiple sources of information to enable rapid triangulation and identification of protein candidates. Possible permutations and underlying principles of this triangulation strategy are elaborated to demonstrate the broad utility of this approach for antigen discovery.

Pd-l1 and Emerging Biomarkers in Immune Checkpoint Blockade Therapy

Abstract PD-L1 checkpoint blockade is revolutionizing cancer therapy, and biomarkers capable of predicting which patients are most likely to respond are highly desired. The detection of PD-L1 protein expression by immunohistochemistry can enrich for response to anti–PD-(L)1 blockade in a variety of tumor types, but is not absolute. Limitations of current commercial PD-L1 immunohistochemical (IHC) assays and improvements anticipated in next-generation PD-L1 testing are reviewed. Assessment of tumor-infiltrating lymphocytes in conjunction with PD-L1 testing could improve specificity by distinguishing adaptive (interferon &ggr; driven and cytotoxic T-lymphocyte associated) from constitutive (non–immune mediated) expression. The presence of a high tumor mutational burden also enriches for response to therapy, and early data indicate that this may provide additive predictive value beyond PD-L1 IHC alone. As candidate biomarkers continue to emerge, the pathologists assessment of the tumor microenvironment on hematoxylin-eosin stain combined with PD-L1 IHC remains a rapid and robust way to evaluate the tumor-immune dynamic.

Pathologic features of response to neoadjuvant anti-PD-1 in resected non-small-cell lung carcinoma: a proposal for quantitative immune-related pathologic response criteria (irPRC)

BackgroundnNeoadjuvant anti-PD-1 may improve outcomes for patients with resectable NSCLC and provides a critical window for examining pathologic features associated with response. Resections showing major pathologic response to neoadjuvant therapy, defined as ≤10% residual viable tumor (RVT), may predict improved long-term patient outcome. However, %RVT calculations were developed in the context of chemotherapy (%cRVT). An immune-related %RVT (%irRVT) has yet to be developed.nnnPatients and methodsnThe first trial of neoadjuvant anti-PD-1 (nivolumab, NCT02259621) was just reported. We analyzed hematoxylin and eosin-stained slides from the post-treatment resection specimens of the 20 patients with non-small-cell lung carcinoma who underwent definitive surgery. Pretreatment tumor biopsies and preresection radiographic tumor measurements were also assessed.nnnResultsnWe found that the regression bed (the area of immune-mediated tumor clearance) accounts for the previously noted discrepancy between CT imaging and pathologic assessment of residual tumor. The regression bed is characterized by (i) immune activation-dense tumor infiltrating lymphocytes with macrophages and tertiary lymphoid structures; (ii) massive tumor cell death-cholesterol clefts; and (iii) tissue repair-neovascularization and proliferative fibrosis (each feature enriched in major pathologic responders versus nonresponders, Pu2009<u20090.05). This distinct constellation of histologic findings was not identified in any pretreatment specimens. Histopathologic features of the regression bed were used to develop Immune-Related Pathologic Response Criteria (irPRC), and these criteria were shown to be reproducible amongst pathologists. Specifically, %irRVT had improved interobserver consistency compared with %cRVT [median per-case %RVT variability 5% (0%-29%) versus 10% (0%-58%), Pu2009=u20090.007] and a twofold decrease in median standard deviation across pathologists within a sample (4.6 versus 2.2, Pu2009=u20090.002).nnnConclusionsnirPRC may be used to standardize pathologic assessment of immunotherapeutic efficacy. Long-term follow-up is needed to determine irPRC reliability as a surrogate for recurrence-free and overall survival.

Abstract 1464: The tumor immune microenvironment is similar in anal squamous cell carcinomas (SCCs) from HIV-infected and uninfected patients

Tumors may evade immune attack by constitutive (oncogene-driven) and/or adaptive (IFN-g inducible) expression of PD-L1. PD-1/PD-L1 blockade can mediate tumor regression in immunocompetent patients. In HIV-infected patients, developing tumors may face little immune selection pressure and therefore may not evolve to evade immune attack. Expression of PD-L1 has not been systematically assessed in cancers from HIV-infected people. In the current study, immunohistochemistry for PD-L1, and CD3 and CD68 (immune cells, ICs) was performed on biopsies from 46 anal SCCs, including 27 from HIV-infected and 19 from uninfected patients. The proportion of cases with tumor cell PD-L1 expression was similar in patients with and without HIV (52% vs. 47%, respectively, p = 0.76), as was the presence of moderate/severely dense ICs (33% vs. 37%, p = 0.81) (Table). Among HIV-infected patients, 19% of anal SCC tumors (5/27) both expressed PD-L1 and had moderate/severe IC infiltration. Tumors from HIV-infected and uninfected patients had similar densities of CD68+ macrophages (mean 517 vs. 404 cells/mm2, p = 0.33) and CD3+ T- lymphocytes (mean 501 vs. 428 cells/mm2, p = 0.57). A component of adaptive PD-L1 expression (juxtaposed to tumor infiltrating ICs) was also observed in both groups (56% vs. 47%, p = 0.58), consistent with comparable T-cell functionality. Further studies will explore the expression of other immune checkpoint proteins and lymphocyte subsets. Despite expectations that cancers from HIV-infected patients would show reduced inflammation, our preliminary findings demonstrate an immune-reactive microenvironment in both HIV+ and HIV- anal SCCs and suggest that anti-PD-1/PD-L1 therapies should be evaluated in anal SCC patients.n Citation Format: Elizabeth L. Yanik, Suzanne L. Topalian, Genevieve Kaunitz, Jessica Esandrio, Tricia Cottrell, Janis M. Taube. The tumor immune microenvironment is similar in anal squamous cell carcinomas (SCCs) from HIV-infected and uninfected patients. [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 1464.

Evaluation of Peritumoral Fibrosis in Metastatic Colorectal Adenocarcinoma to the Liver Using Digital Image Analysis

ObjectivesnIt is challenging to separate peritumoral fibrosis from fibrosis due to chronic liver disease in mass-directed liver biopsies. We evaluated the distance that peritumoral fibrosis extends from metastatic colorectal adenocarcinoma in liver.nnnMethodsnPeritumoral and distant uninvolved liver trichrome stains from 25 cases were analyzed using digital image analysis. Fibrosis was quantitated at concentric intervals from each tumor and in uninvolved liver.nnnResultsnThere was a 3.9 fold (range 0.9-18.6) median increase in fibrosis in the first 0.5 mm of peritumoral liver compared to distant liver. Fibrosis levels returned to baseline at median 2.5 mm (interquartile range 1.5-5.0 mm) from tumor.nnnConclusionsnFibrosis is markedly increased in peritumoral liver. Fibrosis levels returned to baseline by 5 mm from tumor in approximately 75% of cases. Pathologists should be cautious of fibrosis in mass-directed liver biopsies without at least 5 mm of liver tissue distal to the mass.