BackgroundWe recently reported a 56% objective response rate in patients with advanced Merkel cell carcinoma (MCC) receiving pembrolizumab. However, a biomarker predicting clinical response was not identified.MethodsPretreatment FFPE tumor specimens (n = 26) were stained for CD8, PD-L1, and PD-1 by immunohistochemistry/immunofluorescence (IHC/IF), and the density and distribution of positive cells was quantified to determine the associations with anti-PD-1 response. Multiplex IF was used to test a separate cohort of MCC archival specimens (n = 16), to identify cell types expressing PD-1.ResultsTumors from patients who responded to anti-PD-1 showed higher densities of PD-1+ and PD-L1+ cells when compared to non-responders (median cells/mm2, 70.7 vs. 6.7, p = 0.03; and 855.4 vs. 245.0, p = 0.02, respectively). There was no significant association of CD8+ cell density with clinical response. Quantification of PD-1+ cells located within 20 μm of a PD-L1+ cell showed that PD-1/PD-L1 proximity was associated with clinical response (p = 0.03), but CD8/PD-L1 proximity was not. CD4+ and CD8+ cells in the TME expressed similar amounts of PD-1.ConclusionsWhile the binomial presence or absence of PD-L1 expression in the TME was not sufficient to predict response to anti-PD-1 in patients with MCC, we show that quantitative assessments of PD-1+ and PD-L1+ cell densities as well as the geographic interactions between these two cell populations correlate with clinical response. Cell types expressing PD-1 in the TME include CD8+ T-cells, CD4+ T-cells, Tregs, and CD20+ B-cells, supporting the notion that multiple cell types may potentiate tumor regression following PD-1 blockade.Electronic supplementary materialThe online version of this article (10.1186/s40425-018-0404-0) contains supplementary material, which is available to authorized users.

Programmed cell death protein-1 (PD-1)/programmed death ligand-1 (PD-L1) checkpoint blockade has led to remarkable and durable objective responses in a number of different tumor types. A better understanding of factors associated with the PD-1/PD-L axis expression is desirable, as it informs their potential role as prognostic and predictive biomarkers and may suggest rational treatment combinations. In the current study, we analyzedPD-L1,PD-L2,PD-1, and cytolytic activity (CYT) expression, as well as mutational density from melanoma and eight other solid tumor types using The Cancer Genome Atlas database. We found that in some tumor types,PD-L2expression is more closely linked toTh1/IFNGexpression and PD-1 and CD8 signaling thanPD-L1. In contrast, mutational load was not correlated with aTh1/IFNGgene signature in any tumor type.PD-L1,PD-L2,PD-1,CYTexpression, and mutational density are all positive prognostic features in melanoma, and conditional inference modeling revealedPD-1/CYTexpression (i.e., an inflamed tumor microenvironment) as the most impactful feature, followed by mutational density. This study elucidates the highly interdependent nature of these parameters, and also indicates that future biomarkers for anti–PD-1/PD-L1 will benefit from tumor-type–specific, integrated, mRNA, protein, and genomic approaches.

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.

Purpose: PD-L1 expression in the pre-treatment 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 immunohistochemistry (IHC) was performed on thirty-four 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.

Purpose To explore factors associated with response and resistance to anti-PD-1 therapy, we analyzed multiple disease sites at autopsy in a patient with widely metastatic melanoma who had a heterogeneous response. Materials and Methods Twenty-six melanoma specimens (four pre-mortem, 22 post-mortem) were subjected to whole-exome sequencing. Candidate immunologic markers and gene expression were assessed in ten cutaneous metastases showing response or progression during therapy. Results The melanoma was driven by biallelic inactivation of NF1. All lesions had highly concordant mutational profiles and copy number alterations, indicating linear clonal evolution. Expression of candidate immunologic markers was similar in responding and progressing lesions. However, progressing cutaneous metastases were associated with over-expression of genes associated with extracellular matrix and neutrophil function. Conclusions Although mutational and immunologic differences have been proposed as the primary determinants of heterogeneous response/resistance to targeted therapies and immunotherapies, respectively, differential lesional gene expression profiles may also dictate anti-PD-1 outcomes.

Importance The programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) pathway play an important immunosuppressive role in cancer and chronic viral infection, and have been effectively targeted in cancer therapy. Anal squamous cell carcinoma (SCC) is associated with both human papillomavirus and HIV infection. To date, patients with HIV have been excluded from most trials of immune checkpoint blocking agents, such as anti-PD-1 and anti-PD-L1, because it was assumed that their antitumor immunity was compromised compared with immunocompetent patients. Objective To compare the local tumor immune microenvironment (TME) in anal SCCs from HIV-positive and HIV-negative patients. Design, Setting, and Participants Anal SCC tumor specimens derived from the AIDS and Cancer Specimen Resource (National Cancer Institute) and Johns Hopkins Hospital included specimens. Tumors were subjected to immunohistochemical analysis for immune checkpoints (PD-L1, PD-1, LAG-3) and immune cell (IC) subsets (CD3, CD4, CD8, CD68). Expression profiling for immune-related genes was performed on select HIV-positive and HIV-negative cases in PD-L1+ tumor areas associated with ICs. Main Outcomes and Measures Programmed death-ligand 1 expression on tumor cells and ICs, PD-L1 patterns (adaptive vs constitutive), degree of IC infiltration, quantified densities of IC subsets, and gene expression profiles in anal SCCs from HIV-positive vs HIV-negative patients. Results Approximately half of 40 tumor specimens from 23 HIV-positive and 17 HIV-negative patients (29 men and 11 women; mean [SD] age, 51 [9.9] years) demonstrated tumor cell PD-L1 expression, regardless of HIV status. Median IC densities were not significantly decreased in HIV-associated tumors for any cellular subset studied. Both adaptive (IC-associated) and constitutive PD-L1 expression patterns were observed. Immune cell PD-L1 expression correlated with increasing intensity of IC infiltration (r = 0.52; 95% CI, 0.26-0.78; P < .001) and with CD8+ T-cell density (r = 0.35; 95% CI, 0.11-0.59; P = .03). Gene expression profiling revealed comparable levels of IFNG in the TME of both HIV-positive and HIV-negative patients. A significant increase in IL18 expression levels was observed in HIV-associated anal SCCs (fold change, 12.69; P < .001). Conclusions and Relevance HIV status does not correlate with the degree or composition of IC infiltration or PD-L1 expression in anal SCC. These findings demonstrate an immune-reactive TME in anal SCCs from HIV-positive patients and support clinical investigations of PD-1/PD-L1 checkpoint blockade in anal SCC, irrespective of patient HIV status.

Checkpoint inhibitors (CPIs) restore the function of effector immunocytes to target and destroy cancer cells. Immune-related adverse events (irAEs) are a consequence of immune reactivation, with unpredictable inflammatory response, loss of self-tolerance, and development of autoimmunity. Adverse events from CPIs that present as dermatologic toxicities have diverse clinical and histopathologic features. CPI-associated dermatologic toxicities may exhibit histopathologic features of lichenoid dermatitis, bullous pemphigoid, and granulomatous/sarcoid-like reactions. Suprabasal acantholytic dermatologic toxicities associated with CPIs are particularly rare but represent an emerging histopathologic pattern and include lichenoid dermatitis with suprabasal acantholysis/vesicle formation to Grover disease (transient acantholytic dermatosis). Here, we report two patients who developed suprabasal acantholytic dermatologic toxicities during CPI therapy. One patient exhibited a CPI-associated autoimmune blistering disease with paraneoplastic pemphigus (PNP)-like features restricted to histopathology and immunofluorescence, while the other patient had Grover-like lesions. A review of the literature revealed a spectrum of suprabasal acantholytic dermatologic toxicities associated CPIs that may present as lichenoid dermatitis with acantholysis/vesicle formation, Grover-like eruptions, and lesions with PNP-like features restricted to histopathology and immunofluorescence. It is important for clinicians and pathologists to recognize the types of dermatologic toxicities associated with CPIs to direct appropriate therapeutic strategies.

Background: Coronavirus disease 2019 has brought teledermatology to the forefront. Understanding patients' experiences will clarify its benefits and limitations. Materials/Methods: Patients evaluated through live-interactive teledermatology at New York University Langone Health March-June 2020 were surveyed. Patient demographics, satisfaction with, and preferences between teledermatology and in-person visits across four domains (visit preparation, provider communication, physical examination, and treatment plan/follow-up) were collected. Results/Discussion: Of 602 respondents, >70% indicated at least equal satisfaction compared with in-person visits across all domains. More than a quarter of patients were dissatisfied with the virtual examination and more than half preferred in-person examinations. Male gender was associated with treatment plan/follow-up satisfaction (p = 0.03). Patients 66 years preferred in-person visit preparation, communication, and treatment plan/follow-up (all p < 0.01). New patients were less satisfied with teledermatology communication (p = 0.02) and treatment plan/follow-up (p < 0.01) but preferred teledermatology visit preparation (p = 0.01). Conclusions: Patients were satisfied with live-interactive teledermatology during the COVID-19 pandemic, although preferred in-person physical examinations. Satisfaction and preferences varied between patient populations.