Faculty Bibliography

Background: TCR repertoire of TILs is increasingly used as a fingerprint for identifying unique immune responses to cancer and as a biomarker for prognosticating clinical course and response to immunotherapy.
Method(s): CD8+ tumor infiltrating lymphocytes (TILs) obtained from fresh basal cell carcinoma ("BCC") tumor specimens from nodular subtype ("nBCC", n=6) versus infiltrative subtype ("iBCC", n=6) were subject to single-cell VDJ profiling. Data were analyzed using iCellR and ImmunArch.
Result(s): Pooled CD8+ TILs from nBCC and iBCC generated a significantly more diverse TCR repertoire than CD8+ T cells from healthy skin, but a significantly less diverse repertoire than CD8+ from healthy PBMCs. TCR gene bias analysis revealed that nBCC and iBCC TILs expressed a differential preference for certain V genes on both the alpha and beta CDR3 chain. Clonotype analysis revealed the top 10 most expanded clonotypes among iBCC TILs represented 25% of the TCR repertoire versus 20% of the nBCC TIL repertoire; also, iBCC TIL singletons represented 37% of the TCR repertoire while nBCC TIL singletons represented 50% of the TCR repertoire, indicating a greater degree of clonality among iBCC TILs. Additionally, cytotoxic TILs recovered from nBCC possessed a more diverse TCR repertoire than those from iBCC. Moreover, cytotoxic TILs from nBCC possessed a distinct TCR repertoire with little overlap with exhausted TILs; cytotoxic TILs from iBCC possess a TCR repertoire that highly overlapped with exhausted TILs.
Conclusion(s): TILs from nBCC generally possessed a less clonal TCR repertoire than iBCC TILs, possibly contributing to observed relative clinical aggressiveness of these tumors. Additionally, TCR repertoire in exhausted TILs in iBCC overlapped more with cytotoxic TILs, informing clinical decision-making with regards to check point inhibitor immunotherapy.
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Background: The immune tumor microenvironment (TME) is key to controlling disease progression in skin cancer. We aim to compare the TME in these cancers to better inform prognosis and therapeutic decision making.
Method(s): CD8+ tumor infiltrating lymphocytes (TILs) obtained from fresh immunocompetent SCC (n=5) and BCC (n=12) tumors and solid-organ transplant recipient SCC ("TSCC", n=6) tumors were subject to single-cell RNA profiling. Data were analyzed using iCellR.
Result(s): CD8+ TILs were clustered based on gene expression: cytotoxic (GZMA, GZMB, IFN-gamma, PRF1); naive (CCR7, LEF1, TCF7, IL7R, OX40); exhausted (BTLA, CTLA4, PDCD1, TIM3, LAG3, STAT3, 4-1BB); and regulatory (FOXP3, TIM3, OX40); additional subtypes were observed for naive, exhausted, and regulatory T cells. Similar percentages of cytotoxic TILs were observed in SCC and BCC, significantly greater than in TSCC. Conversely, TSCC had the highest percentage of exhausted TILs. TSCC exhausted cells also tended to be more terminally exhausted, while those in SCC and BCC tended to be more progenitor exhausted. While the overall percentage of the regulatory CD8 compartment was similar across all three groups, SCC had a significantly greater proportion of a more suppressive subtype.
Conclusion(s): Many significant differences in the CD8 TME were observed between SCC, TSCC, and BCC. TSCC was associated with a proportionally larger and extensively terminally exhausted CD8 compartment. BCC was also associated with a significantly greater exhausted compartment than SCC, possibly correlating to the relatively slow-growing clinical course of BCC. Additionally, SCC was associated with a significantly greater proportion of more suppressive regulatory CD8s, possibly correlating to the greater clinical aggressiveness of SCC.
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Importance/UNASSIGNED:There is a paucity of evidence to guide physicians regarding prevention strategies for cutaneous squamous cell carcinoma (CSCC) in solid organ transplant recipients (SOTRs). Objective/UNASSIGNED:To examine the development and results of a Delphi process initiated to identify consensus-based medical management recommendations for prevention of CSCC in SOTRs. Evidence Review/UNASSIGNED:Dermatologists with more than 5 years' experience treating SOTRs were invited to participate. A novel actinic damage and skin cancer index (AD-SCI), consisting of 6 ordinal stages corresponding to an increasing burden of actinic damage and CSCC, was used to guide survey design. Three sequential web-based surveys were administered from January 1, 2019, to December 31, 2020. Pursuant to Delphi principles, respondents thoroughly reviewed all peer responses between rounds. Supplemental questions were also asked to better understand panelists' rationale for their responses. Findings/UNASSIGNED:The Delphi panel comprised 48 dermatologists. Respondents represented 13 countries, with 27 (56%) from the US. Twenty-nine respondents (60%) were Mohs surgeons. Consensus was reached with 80% or higher concordance among respondents when presented with a statement, question, or management strategy pertaining to prevention of CSCC in SOTRs. A near-consensus category of 70% to less than 80% concordance was also defined. The AD-SCI stage-based recommendations were established if consensus or near-consensus was achieved. The panel was able to make recommendations for 5 of 6 AD-SCI stages. Key recommendations include the following: cryotherapy for scattered actinic keratosis (AK); field therapy for AK when grouped in 1 anatomical area, unless AKs are thick in which case field therapy and cryotherapy were recommended; combination lesion directed and field therapy with fluorouracil for field cancerized skin; and initiation of acitretin therapy and discussion of immunosuppression reduction or modification for patients who develop multiple skin cancers at a high rate (10 CSCCs per year) or develop high-risk CSCC (defined by a tumor with approximately ≥20% risk of nodal metastasis). No consensus recommendation was achieved for SOTRs with a first low risk CSCC. Conclusions and Relevance/UNASSIGNED:Physicians may consider implementation of panel recommendations for prevention of CSCC in SOTRs while awaiting high-level-of-evidence data. Additional clinical trials are needed in areas where consensus was not reached.

Standard histopathology is currently the gold standard for assessment of margin status in Mohs surgical removal of skin cancer. Ex vivo confocal microscopy (XVM) is potentially faster, less costly and inherently 3D/digital compared to standard histopathology. Despite these advantages, XVM use is not widespread due, in part, to the need for pathologists to retrain to interpret XVM images. We developed artificial intelligence (AI)-driven XVM pathology by implementing algorithms that render intuitive XVM pathology images identical to standard histopathology and produce automated tumor positivity maps. XVM images have fluorescence labeling of cellular and nuclear biology on the background of endogenous (unstained) reflectance contrast as a grounding counter-contrast. XVM images of 26 surgical excision specimens discarded after Mohs micrographic surgery were used to develop an XVM data pipeline with 4 stages: flattening, colorizing, enhancement and automated diagnosis. The first two stages were novel, deterministic image processing algorithms, and the second two were AI algorithms. Diagnostic sensitivity and specificity were calculated for basal cell carcinoma detection as proof of principal for the XVM image processing pipeline. The resulting diagnostic readouts mimicked the appearance of histopathology and found tumor positivity that required first collapsing the confocal stack to a 2D image optimized for cellular fluorescence contrast, then a dark field-to-bright field colorizing transformation, then either an AI image transformation for visual inspection or an AI diagnostic binary image segmentation of tumor obtaining a diagnostic sensitivity and specificity of 88% and 91% respectively. These results show that video-assisted micrographic XVM pathology could feasibly aid margin status determination in micrographic surgery of skin cancer.

It is well known that solid-organ transplant recipients (SOTRs) have a 65- to 100-fold increase in the risk of developing skin cancer, namely, nonmelanoma skin cancers (NMSCs) such as cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC). In addition, these patients are also at increased risk for development of melanoma as well as other less common cutaneous malignancies (Merkel's cell carcinoma, Kaposi's sarcoma). SOTRs with NMSC (namely cSCC) are also at significantly increased risk of poor clinical outcomes including local recurrence, nodal and distant metastasis, and disease-specific death relative to patients who are not immunosuppressed. Increased surveillance and monitoring in patients at risk of aggressive disease and poor outcomes who are on immunosuppression is essential in patients with lung transplants given the high degree of immunosuppression. Increased awareness of risks, treatments, and management allows for improved outcomes in these patients. This article will provide an overview of the risk factors for the development of cutaneous malignancies in organ transplant recipients as well as a detailed discussion of various immunosuppressant and prophylactic medications used in this patient population that contribute to the risk of developing cutaneous malignancies, with an emphasis on NMSC (cSCC and BCC) in lung transplant recipients. Finally, this article includes a discussion on the clinical and dermatologic management of this high-risk immunosuppressed population including a review of topical and systemic agents for field therapy of actinic damage and chemoprevention of keratinocyte carcinomas. In addition, indications for additional treatment and preventive measures such as adjuvant radiation treatment after surgical management of cutaneous malignancies and potential modification of immunosuppressive medication regimens are discussed.

Merkel cell carcinoma (MCC) is an aggressive and rare cutaneous cancer of the mechanoreceptor unit of the skin with a neuroendocrine origin. MCC incidence has been on the rise over the past two decades. Risk factors include old age, chronic UV exposure, and immunosuppression. Although MCC is a cutaneous malignancy that is often misdiagnosed as a benign nodule at the time of diagnosis, it has an aggressive disease course due to its high recurrence and metastatic potential. The PD-1/PD-L1 checkpoint blockade has recently shown promising results in the management of advanced MCC. Avelumab and pembrolizumab are considered the new standard of care for metastatic MCC. Despite advances in the field, studies are needed to elucidate the role of immunotherapy for patients who are resistant to treatment. Most ongoing clinical trials aim to assess the efficacy of checkpoint inhibitor combination therapies. This article reviews the most current literature on the surgical and medical management of MCC.