Single cell transcriptomics reveals dysregulated immnue homeostasis in different stages in HPV-induced cutaneous squamous cell carcinoma.

In order to explore the huge impact of impaired immnue homeostasis on the occurrence and development of cutaneous squamous cell carcinoma (cSCC), and investigate characterization of the cellular components and their changes which is crucial to understanding the pathologic process of HPV-induced cSCC, we diagnosed and followed up on a very rare HPV-induced cSCC patient who progressed at a very fast rate and transferred to death quickly. We performed single-cell RNA sequencing (scRNA-seq) of 11 379 cells from the skin tissues of this patient with four different skin statuses after HPV infection. Immunofluorescence experiments were used for validation. scRNA-seq identified that CD52+ HLA-DOA- macrophages only existed in paracancerous cutaneous squamous cell carcinoma (pc-cSCC) and cSCC tissue. Besides, immune cells including CD8+ exhausted T cells and CD4+ regulatory T cells as well as matrix cells like MMP1+, and MMP11+ fibroblasts were gradually increased. Meanwhile, COMP+ ASPN+ fibroblasts gradually decreased. Cell interaction analysis revealed enhancement in interactions between monocytes/macrophages, fibroblasts and tumour-specific keratinocytes. scRNA-seq was performed in HPV-induced cSCC for the first time, to explore the correlation between infection and tumour. It is the first time to study the development of tumours from different stages of infection in HPV-induced cSCC. In this study, the tumour itself and the tumour microenvironment were both analysed and explored. And it was validated in clinical samples from different patients. Our findings reveal the dynamic immnue homeostasis from normal skin to cSCC tissue, this alteration might drive HPV-induced cSCC.

Metastatic Axillary Cutaneous Squamous Cell Carcinoma in an African-American Female: A Rare Case.

Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer, typically affecting older White males in sun-exposed areas, and metastasis is rare. We present a unique case of a 46-year-old obese African-American woman with a recurrent, deep abscess in her left axilla. It was initially treated with several incision and drainage procedures and antibiotics. Despite multiple interventions, the abscess recurred with severe pain and drainage. Subsequent biopsies revealed a high-grade malignant neoplasm, later confirmed as poorly differentiated cSCC with primary metastases to the lungs and secondary metastases to the adrenal glands and periaortic lymph nodes. Immunohistochemical staining supported the diagnosis. The patient's atypical presentation, including her race, a non-sun-exposed site, and younger age, highlights the need for vigilance in diagnosing cSCC in atypical cases. This case underscores the importance of early consideration of cSCC in differential diagnoses for persistent or recurrent abscesses, which can facilitate timely treatment, potentially preventing extensive metastasis and improving patient outcomes.

Immune Checkpoints and Cellular Landscape of the Tumor Microenvironment in Non-Melanoma Skin Cancer (NMSC).

Non-melanoma skin cancer (NMSC) is primarily categorized into basal cell carcinoma (BCC), the most prevalent form of skin cancer, and cutaneous squamous cell carcinoma (cSCC), the second most common type. Both BCC and cSCC represent a significant health burden, particularly in immunocompromised individuals and the elderly. The immune system plays a pivotal role in the development and progression of NMSC, making it a critical focus for therapeutic interventions. This review highlights key immunological targets in BCC and cSCC, with a focus on immune checkpoint molecules such as PD-1/PD-L1 and CTLA-4, which regulate T cell activity and contribute to immune evasion. This review also highlights anti-tumor immune cell subsets within the tumor microenvironment (TME), such as tumor-infiltrating lymphocytes (TILs) and dendritic cells. Additionally, it examines the immunosuppressive elements of the TME, including regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and cancer-associated fibroblasts (CAFs), as well as their roles in NMSC progression and resistance to therapy. Emerging strategies targeting these immune elements, such as monoclonal antibodies, are also discussed for their potential to enhance anti-tumor immune responses and improve clinical outcomes. By elucidating the immunological landscape of BCC and cSCC and drawing comparisons to melanoma, this review highlights the transformative potential of immunotherapy in treating these malignancies.

Predicting adjuvant radiation therapy benefit in cutaneous squamous cell carcinoma with the 40-gene expression profile.

Aim: To independently confirm that the 40-gene expression profile (40-GEP) test can identify patients with high-risk cutaneous squamous cell carcinoma who are more or less likely to benefit from adjuvant radiation therapy (ART).Materials & methods: Primary cutaneous squamous cell carcinoma tumors from two academic centers received retrospective 40-GEP testing and were analyzed for 5-year metastasis-free survival and projected time to event.Results: Random sampling of matched patient pairs (n = 52 ART-treated; 371 no ART) showed a median 50% decrease in 5-year progression rate for ART-treated patients (vs no ART) with 40-GEP Class 2B. Class 2A was associated with a modest ART benefit, but not Class 1.Conclusion: The 40-GEP identified patients most likely to benefit from ART (Class 2B) and those that can consider deferring treatment (Class 1).

Independent validation study: 40-GEP identifies patients with cutaneous squamous cell carcinoma who would be most likely to benefit from adjuvant radiation therapy.

Cervical squamous cell carcinoma outcomes across continents: A retrospective study.

OBJECTIVE: To assess the influence of geographies and race on the survival outcomes in patients diagnosed with cervical squamous cell carcinoma (CSCC) across three continents. METHODS: This multicontinental retrospective study was conducted in 8 hospitals across Asia, Europe, and North America (NA). Clinicopathologic data of 595 patients with presumed early stages of CSCC, treated surgically, with curative intent was collected. Descriptive analysis and Cox regression models were produced. RESULTS: A total of 595 patients, consisting of 445 (74.8 %) white, 75 (12.6 %) Blacks, and 75 (12.6 %) Asian patients were included. Geographical distribution comprised 69 % of patients from NA, 22 % from Europe, and 9 % from Asia. The median age at diagnosis was 46 years. The median overall survival (OS) and relapse-free survival (RFS) were 22.09 years and 21.19 years, respectively. Patient characteristics varied significantly across geographical regions, except for consensus tumor grade. Patients in Europe from middle-income countries with limited CC screening had a substantially higher risk of death than those in NA (HR, 1.79; 95 % CI, 1.13 to 2.79; p = 0.015). Patients from single center in Japan had higher risk of relapse than those from the four heterogeneous NA centers (sub-distribution hazard ratio, 2.19; 95 % CI, 1.22 to 3.95; p = 0.009), although OS did not differ significantly. Race remained statistically insignificant for survival outcomes across the three continents but seemed to influence survival outcomes in NA centers. CONCLUSION: Our study highlights impact of geographies and races on CSCC survival outcomes, emphasizing the need of considering these factors when developing targeted interventions against CSCC.

Comparative Analysis of Inhibitory and Activating Immune Checkpoints PD-1, PD-L1, CD28, and CD86 in Non-Melanoma Skin Cancer.

The establishment of immunotherapy applying immune checkpoint inhibitors (ICI) has provided an important new option for the treatment of solid malignant diseases. However, different tumor entities show dramatically different responses to this therapy. BCC responds worse to anti-PD-1 ICIs as compared to cSCC. Differential immune checkpoint expression could explain this discrepancy and, therefore, the aim of this study was to analyze activating and inhibitory immune checkpoints in cSCC and BCC tissues. Tissue microarrays of the invasive front as well as the tumor core of BCC and cSCC samples were used to evaluate PD-1, PD-L1, CD28, and CD86 expression and their topographic distribution profiles by chromogenic immunohistochemistry. QuPath was used to determine the labeling index. The expression of PD-1, PD-L1, and CD28 was significantly higher in both the tumor core and the invasive front of cSCC samples as compared to BCC (p < 0.001). In addition, the ratios of PD-L1/CD86 (p < 0.001) and CD28/CD86 (p < 0.001) were significantly higher in cSCC. The invasive front of both tumor entities showed higher expression levels of all immune markers compared to the tumor core in both tumor entities. The significantly higher expression of PD-1, PD-L1, and CD28 in cSCC, along with the predominance of the inhibitory ligand PD-L1 as compared to the activating CD86 in cSCC, provide a potential explanation for the better objective response rates to anti-PD-1 immunotherapy as compared to BCC. Furthermore, the predominant site of interaction between the immune system and the tumor was within the invasive front in both tumor types.

Overexpression of CCL-20 and CXCL-8 genes enhances tumor escape and resistance to cemiplimab, a programmed cell death protein-1 (PD-1) inhibitor, in patients with locally advanced and metastatic cutaneous squamous cell carcinoma.

Cemiplimab has demonstrated relevant clinical activity in cutaneous squamous cell carcinoma (cSCC) but mechanisms of primary and acquired resistance to immunotherapy are still unknown. We collected clinical data from locally advanced and/or metastatic cSSC patients treated with cemiplimab in two Italian University centers. In addition, gene expression analysis by using Nanostring Technologies platform to evaluate 770 cancer- and immune-related genes on 20 tumor tissue samples (9 responders and 11 non-responders to cemiplimab) was performed. We enrolled 81 patients with a median age of 82 years. After 16.4 months of median follow-up, 12- and 24-months PFS were 53% and 42%, respectively; while 12- and 24-months OS were 71% and 61%, respectively. Treatment was well tolerated. Overall response rate (ORR) was 58%, with a disease control rate (DCR) of 77.8%. The difference between genes expressed in responder versus non-responder patient samples was substantial, particularly for genes involved in immune system regulation. Cemiplimab-resistant tumors were associated with over-expression of CCL-20 and CXCL-8. Cemiplimab confirmed efficacy and safety data in real-life cSCC patients. Overexpression of CCL-20 and CXCL-8 could represent biomarkers of lack of response to immunotherapy.

The Mutational and Microenvironmental Landscape of Cutaneous Squamous Cell Carcinoma: A Review.

Cutaneous squamous cell carcinoma (cSCC) manifests through the complex interactions of UV-induced DNA damage, genetic mutations, and alterations in the tumor microenvironment. A high mutational burden is present in cSCC, as well as both cSCC precursors and normal skin, making driver genes difficult to differentiate. Despite this, several key driver genes have been identified, including TP53, the NOTCH family, CDKN2A, PIK3CA, and EGFR. In addition to mutations, the tumor microenvironment and the manipulation and evasion of the immune system play a critical role in cSCC progression. Novel therapeutic approaches, such as immunotherapy and EGFR inhibitors, have been used to target these dysregulations, and have shown promise in treating advanced cSCC cases, emphasizing the need for targeted interventions considering both genetic and microenvironmental factors for improved patient outcomes.

The Role of the Neurotrophin Network in Skin Squamous Cell Cancer and the Novel Use of the Zebrafish System.

Cutaneous squamous cell carcinoma (cSCC) is the second most prevalent form of skin cancer. An increasing number of cSCCs are associated with dysregulation of key molecules that control skin homeostasis. These observations have increased interest in the role of neurotrophins and their receptors in the pathogenesis of cSCC. They have been demonstrated to have a considerable impact on the aggressiveness potential of skin cancer by both in vitro and in vivo models. In this context, mouse models are classically used to dissect proliferation versus differentiation balance, but they have some limitations in terms of time, space, and costs. Recently, zebrafish models have been implemented as a new tool to obtain information regarding the invasive capacity and metastasis of neoplastic cells. By xenotransplantation technique, cSCC cells from a patient's biopsy or cell line can be successfully characterized, with or without the presence of genetic manipulation or treatments. In addition, the evaluation of the immune microenvironment contributes to potentially identifying connections and homologies with humans. In this review, we retrace the role of the neurotrophin network in healthy and pathological skin, particularly in cSCC. We review how zebrafish models can be important tools for studying cSCC development, growth, and potential treatments.

Real-world evidence study on the early use of cemiplimab in the UK: REACT-CEMI (Real World evidence of advanced CSCC treatment with cemiplimab).

Background: Cemiplimab was licensed in the United Kingdom (UK) in 2019 for the treatment of patients with locally advanced and metastatic CSCC not suitable for curative surgery or radiotherapy (advanced CSCC [aCSCC]). No UK multi-center studies have investigated the real-world experience of cemiplimab post marketing authorization in aCSCC. Methods: This non-interventional retrospective study (10 UK centers) involved data collection from medical records of patients with aCSCC who initiated cemiplimab treatment between 2 July 2019 and 30 November 2020. The study period was a minimum of 12 and a maximum of 36 months post cemiplimab initiation. The primary objective was to describe the real-world clinical effectiveness of cemiplimab (primary outcome: overall response rate [ORR]). Results: Of 105 patients, 70% (n=73/105) were male (median [range] age at index of 78.5 [55.4-93.2] years); most patients (63% [n=50/80]) had an Eastern Cooperative Oncology Group (ECOG) score of 1 and 62% (n=63/102) had metastatic disease. The ORR within 12 months was 42% (95% confidence interval [CI] 32%-51%) and the disease control rate was 62% (n=65/105). The median (95% CI) real-world progression-free survival and overall survival from index was 8.6 (6.0-18.7) and 21.0 (14.7-25.2) months, respectively. The median (range) number of cemiplimab infusions was 11.0 (1.0-44.0). Eighty-seven percent experienced no cemiplimab treatment interruptions; 13% (n=14/105) interrupted treatment due to immune-related adverse reactions (irARs) (47% [n=9/19] of treatment interruption events). Eighty-five percent (n=89/105) of patients had discontinued cemiplimab treatment by the end of the study; where reasons for discontinuation were recorded, 20% (n=17/87) discontinued due to the completion of their 2-year treatment course. Nineteen percent (n=20/105) of patients experienced irARs. Conclusion: Effectiveness and safety data in this study are broadly similar to previous real-world studies of cemiplimab and the EMPOWER-CSCC1 clinical trial; with our cohort representing a broader population (included immunocompromised and transplant patients). Results support the use of cemiplimab for the treatment of aCSCC in a real-world setting.

IGF1R signaling induces epithelial-mesenchymal plasticity via ITGAV in cutaneous carcinoma.

BACKGROUND: Early cutaneous squamous cell carcinomas (cSCCs) generally show epithelial differentiation features and good prognosis, whereas advanced cSCCs present mesenchymal traits associated with tumor relapse, metastasis, and poor survival. Currently, the mechanisms involved in cSCC progression are unclear, and the established markers are suboptimal for accurately predicting the clinical course of the disease. METHODS: Using a mouse model of cSCC progression, expression microarray analysis, immunofluorescence and flow cytometry assays, we have identified a prognostic biomarker of tumor relapse, which has been evaluated in a cohort of cSCC patient samples. Phosphoproteomic analysis have revealed signaling pathways induced in epithelial plastic cancer cells that promote epithelial-mesenchymal plasticity (EMP) and tumor progression. These pathways have been validated by genetic and pharmacological inhibition assays. RESULTS: We show that the emergence of epithelial cancer cells expressing integrin αV (ITGAV) promotes cSCC progression to a mesenchymal state. Consistently, ITGAV expression allows the identification of patients at risk of cSCC relapse above the currently employed clinical histopathological parameters. We also demonstrate that activation of insulin-like growth factor-1 receptor (IGF1R) pathway in epithelial cancer cells is necessary to induce EMP and mesenchymal state acquisition in response to tumor microenvironment-derived factors, while promoting ITGAV expression. Likewise, ITGAV knockdown in epithelial plastic cancer cells also blocks EMP acquisition, generating epithelial tumors. CONCLUSIONS: Our results demonstrate that ITGAV is a prognostic biomarker of relapse in cSCCs that would allow improved patient stratification. ITGAV also collaborates with IGF1R to induce EMP in epithelial cancer cells and promotes cSCC progression, revealing a potential therapeutic strategy to block the generation of advanced mesenchymal cSCCs.

GBP1 promotes cutaneous squamous cell carcinoma proliferation and invasion through activation of STAT3 by SP1.

Cutaneous squamous cell carcinoma (cSCC) ranks as the second most prevalent skin tumour (excluding melanoma). However, the molecular mechanisms driving cSCC progression remain elusive. This study aimed to investigate GBP1 expression in cSCC and elucidate its potential molecular mechanisms underlying cSCC development. GBP1 expression was assessed across public databases, cell lines and tissue samples. Various assays, including clone formation, CCK8 and EdU were employed to evaluate cell proliferation, while wound healing and transwell assays determined cell migration and invasion. Subcutaneous tumour assays were conducted to assess in vivo tumour proliferation, and molecular mechanisms were explored through western blotting, immunofluorescence and immunoprecipitation. Results identified GBP1 as an oncogene in cSCC, with elevated expression in both tumour tissues and cells, strongly correlating with tumour stage and grade. In vitro and in vivo investigations revealed that increased GBP1 expression significantly enhanced cSCC cell proliferation, migration and invasion. Mechanistically, GBP1 interaction with SP1 promoted STAT3 activation, contributing to malignant behaviours. In conclusion, the study highlights the crucial role of the GBP1/SP1/STAT3 signalling axis in regulating tumour progression in cSCC. These findings provide valuable insights into the molecular mechanisms of cSCC development and offer potential therapeutic targets for interventions against cSCC.

Anti-tumor effects of tirbanibulin in squamous cell carcinoma cells are mediated via disruption of tubulin-polymerization.

Topical tirbanibulin is a highly effective and well tolerated novel treatment option for actinic keratoses (AKs). This study aimed to characterize the mode of action of tirbanibulin in keratinocytes (NHEK) and cutaneous squamous cell carcinoma (cSCC) cell lines (A431, SCC-12) in vitro. Tirbanibulin significantly reduced proliferation in a dose-dependent manner in all investigated cell lines, inhibited migration, and induced G2/M-cell cycle arrest only in the cSCC cell lines analyzed, and induced apoptosis solely in A431, which showed the highest sensitivity to tirbanibulin. In general, we detected low basal expression of phosphorylated SRC in all cell lines analyzed, therefore, interference with SRC signaling does not appear to be the driving force regarding the observed effects of tirbanibulin. The most prominent tirbanibulin-mediated effect was on ß-tubulin-polymerization, which was especially impaired in A431. Additionally, tirbanibulin induced an increase of the proinflammatory cytokines IL-1α, bFGF and VEGF in A431. In conclusion, tirbanibulin mediated anti-tumor effects predominantly in A431, while healthy keratinocytes and more dedifferentiated SCC-12 were less influenced. These effects of tirbanibulin are most likely mediated via dysregulation of ß-tubulin-polymerization and may be supported by proinflammatory aspects.

Targeting of S-phase kinase associated protein 2 stabilized tumor suppressors leading to apoptotic cell death in squamous skin cancer cells.

S-phase kinase-associated protein 2 (Skp2) is an F-box protein overexpressed in human cancers and linked with poor prognosis. It triggers cancer pathogenesis, including stemness and drug resistance. In this study, we have explored the potential role of Skp2 targeting in restoring the expression of tumor suppressors in human cutaneous squamous cell carcinoma (cSCC) cells. Our results showed that genetic and pharmacological Skp2 targeting markedly suppressed cSCC cell proliferation, colony growth, spheroid formation, and enhanced sensitization to chemotherapeutic drugs. Further, western blot results demonstrated restoration of tumor suppressor (KLF4) and CDKI (p21) and suppression of vimentin and survivin in Skp2-knocked-down cSCC cells. Importantly, we also explored that Skp2 targeting potentiates apoptosis of cSCC cells through MAPK signaling. Moreover, co-targeting of Skp2 and PI3K/AKT resulted in increased cancer cell death. Interestingly, curcumin, a well-known naturally derived anticancer agent, also inhibits Skp2 expression with concomitant CDKI upregulation. In line, curcumin suppressed cSCC cell growth through ROS-mediated apoptosis, while the use of N-acetyl cysteine (NAC) reversed curcumin-induced cell death. Curcumin treatment also sensitized cSCC cells to conventional anticancer drugs, such as cisplatin and doxorubicin. Altogether, these data suggest that Skp2 targeting restores the functioning of tumor suppressors, inhibits the expression of genes associated with cell proliferation and stemness, and sensitizes cancer cells to anticancer drugs. Thus, genetic, and pharmacological ablation of Skp2 can be an important strategy for attenuating cancer pathogenesis and associated complications in skin squamous cell carcinoma.

Echinatin suppresses cutaneous squamous cell carcinoma by targeting GSTM3-mediated ferroptosis.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin cancers for which effective drugs are urgently needed. Echinatin, a natural compound extracted from Glycyrrhiza plants, has shown promising antitumour effects. However, the efficacy and the direct target of echinatin in cSCC remain unclear. PURPOSE: This study conducted a systematic investigation of the antitumour effects of echinatin on cSCC and the underlying mechanisms involved. STUDY DESIGN AND METHODS: Three cSCC cell lines, a xenograft model, and a UV-induced cSCC mouse model were used to investigate the potential protective effects of echinatin. The interactions between echinatin and glutathione S-transferase mu3 (GSTM3) and between echinatin and peroxiredoxin-2 (PRDX2) were evaluated by a proteome microarray assay, pull-down LC‒MS/MS analysis, surface plasmon resonance, and molecular docking. The potential mechanisms of GSTM3-mediated echinatin activity were analysed by using western blotting, lentivirus infection and small interfering RNA (siRNA) transfection. RESULTS: In this study, we found that echinatin inhibited the proliferation and migration of cSCC cells but had no cytotoxic effect on primary human keratinocytes. Furthermore, echinatin significantly inhibited tumour growth in vivo. Mechanistically, our data showed that echinatin could directly bind to GSTM3 and PRDX2. Notably, echinatin inhibited GSTM3 and PRDX2 levels by promoting their proteasomal degradation, which led to the disruption of ROS production. We then revealed that echinatin increased mitochondrial ROS production by inhibiting GSTM3. Moreover, echinatin triggered ferroptosis by inhibiting GSTM3-mediated ferroptosis negative regulation (FNR) proteins. In addition, echinatin regulated GSTM3-mediated ROS/MAPK signalling. CONCLUSION: Echinatin has good antitumour effects both in vitro and in vivo. Moreover, our findings indicate that GSTM3 and PRDX2 could function as viable targets of echinatin in cSCC. Consequently, echinatin represents a novel treatment for cSCC through the targeting of GSTM3-mediated ferroptosis.

Mutational Profiles of Cutaneous Squamous Cell Carcinomas with Different Patterns of Clinical Aggression from Head and Neck Regions.

Cutaneous squamous cell carcinoma is a prevalent malignancy with a rising incidence and a notably high mutational load. Exploring the genetic nuances of cSCC and investigating molecular approaches stands as a potential avenue for improving outcomes in high-risk patients. This retrospective case-control study involved two cohorts, one of 14 patients (the "discovery cohort") and the other of 12 patients (the "validation cohort"), with cSCC located in the head/neck anatomical region and diagnosed at the pT2 stage. Overall, cases developed early local relapses of the disease, whereas controls never relapsed during the entire follow-up period. A next-generation sequencing (NGS) approach conducted on histological samples revealed that TP53 and CDKN2A were the most frequently mutated genes in our series. No specific mutations were identified as potential prognostic or therapeutic targets. Controls exhibited a tendency toward a higher mutational rate compared to cases. It is possible that an increased number of mutations could prompt the cSCC to expose more antigens, becoming more immunogenic and facilitating recognition by the immune system. This could enhance and sustain the immunological response, potentially preventing future recurrences.

Metastatic patterns and treatment options for head and neck cutaneous squamous cell carcinoma (Review).

According to current predictions, one-fifth of all Americans will develop skin cancer during their lifetime. Cutaneous squamous cell carcinoma (cSCC) most commonly occurs in the head and neck region, which is the area of the body with the highest level of sun exposure. High-risk head and neck cSCC (HNcSCC) is a broad category with numerous high-risk factors that are associated with unfavorable results. In cSCC staging systems, clinical and tumor traits that are likely to result in poor outcomes are identified. Metastasis occurs in ~2.5% of patients with cSCC, most often in the local lymph nodes, and there is some indication that lymph node metastasis has a distinct pattern based on the tumor site. Current findings on tumor molecular targets have suggested the use of systemic treatments, particularly immunotherapy (such as cemiplimab, pembrolizumab and nivolumab), over radiotherapy or chemotherapy for this type of metastasis. However, when used simultaneously with immunotherapy, radiotherapy may be beneficial in the treatment of metastatic HNcSCC by improving the efficacy of immunotherapy. The present review aims to assess the existing literature on metastatic HNcSCC pathways and treatment options, in order to define current and future directions. Notably, there is an urgent need to identify patients who may benefit from local or systemic cancer treatments. The treatment of lymph node metastasis presents a therapeutic challenge and requires comprehensive management.

Cemiplimab-Induced Hyperosmolar Hyperglycemic State With Concurrent Diabetic Ketoacidosis in a Patient Receiving Treatment for Cutaneous Squamous Cell Carcinoma.

The immune checkpoint inhibitor (ICI) cemiplimab is a human monoclonal antibody used in the treatment of locally advanced and metastatic cutaneous squamous cell carcinoma (CSCC) not amenable to surgery or radiation therapy. Although cemiplimab shows excellent efficacy with a good tolerability profile, it can cause side effects, including potentially life-threatening endocrinopathies. We discuss the case of a 77-year-old Caucasian female with CSCC treated with only three cycles of cemiplimab who presented with altered mental status and was found to have severe hyperglycemia, hyperosmolarity, ketonemia, glucosuria, and ketonuria concerning for hyperosmolar hyperglycemic syndrome (HHS) with concurrent diabetic ketoacidosis (DKA). The patient made a rapid recovery in the hospital while on standard therapies for HHS/DKA and cemiplimab was discontinued upon discharge. While there have been reports of cemiplimab-induced DKA, to our knowledge, this is the first reported case of cemiplimab-induced HHS-DKA. This report aims to shed light on cemiplimab-induced HHS-DKA and to underscore the need to elucidate the molecular mechanisms underlying ICI-induced diabetes mellitus (ICI-DM).

Intralesional 5-Fluorouracil in the Treatment of Squamous Cell Carcinoma in an Elderly Patient.

Squamous cell carcinoma (SCC) is the second leading form of skin cancer. In the elderly population, surgery may carry more risk and significant morbidity in comparison to less invasive forms of treatment. This case report describes the successful use of intralesional 5-fluorouracil (IL5-FU) to treat cutaneous squamous cell carcinoma (cSCC). A 98-year-old white woman presented in early May 2017 with a 3.5-cm rapidly growing crusted nodule on her left proximal-lateral arm. She had a past medical history of chronic obstructive pulmonary disease, atrial fibrillation, and heart failure. The patient also had a frail body habitus and weighed 80 pounds. Physical examination revealed a large, ulcerated, crateriform mass on the left proximal-lateral arm. A shave biopsy was performed, which revealed a well-differentiated SCC, composed of nodular masses of neoplastic squamous cells with atypical nuclei, keratin pearl formation, and scattered mitotic figures with surrounding fibrosis and inflammation. The patient was wheelchair-bound and oxygen-dependent and, thus, not considered a good surgical or radiation candidate. Treatment was decided with 5-fluorouracil. At a four-week follow-up appointment, there was no visible or palpable evidence of the tumor. There was no sign of recurrence at three months, indicating treatment success. The patient later died due to cardiac arrest in September 2017. The elderly population with cSCC can benefit from intervention and treatment with IL5-FU when surgery is not an option due to patient comorbidities. IL5-FU can potentially be used in areas where access to a dermatologist, surgeon, or surgical services is limited.