Does the nature of residual immune function explain the differential risk of non-melanoma skin cancer development in immunosuppressed organ transplant recipients?

Effect of education on sun-safe behaviour in kidney transplant recipients

BACKGROUND

Organ transplant recipients (OTR) are more likely to develop skin cancer than the general population. One of the main components of the exposome that triggers the development of skin tumours is solar ultraviolet (UV) radiation. To reduce the incidence of harmful consequences of sun exposure, sun protection education is needed for patients taking long-term immunosuppressive drugs.

METHODS

In a previous study, we assessed the sun-safe behaviour of 221 OTR using a questionnaire before and after transplantation and personally educated the patients about proper sun protection. After the education, there were no further reminder presentations. Presently, the sun protection and sun seeking habits of the available 176 of these patients were questioned to assess the long-term effect of the previous sun protection education.

RESULTS

Two-four years after the education, more patients wore hats and protected their skin with long-sleeved clothing than before the education. In terms of sun seeking habits, both occupational and recreational sun exposure decreased significantly. Significantly fewer people went on holiday after transplantation, but those who went on holiday spent significantly less time in the sun.

CONCLUSION

The long-term positive effects of education can be seen both in the patients' sun protection and in their sun seeking habits. However, the long-term goal is to maintain these results and thereby reduce the likelihood of skin tumours and consequently the associated tumour death.

Predicting Tacrolimus Concentrations in the Skin of Adult Kidney Transplant Recipients: A Feasibility Study

Solid organ transplant recipients are at an increased risk of developing skin cancers due to chronic immunosuppression, particularly with calcineurin inhibitors. Tacrolimus is the most prescribed calcineurin inhibitor in this patient cohort, and understanding tacrolimus concentrations in the skin will facilitate the development of anti-cancer preventive and therapeutic strategies. Here, we show that in mice, tacrolimus blood levels peaked rapidly ∼1 h post last oral dose while skin levels rose more slowly and remained high for at least 6 h. Subsequently, tacrolimus skin and blood concentrations were assessed in 15 kidney transplant recipients. The mean age was 61 years, the average time post-transplant was 7 years (range 0-21 years) and 87% were male. The average skin sampling time post tacrolimus dosing was 6 h 32 min. Skin tacrolimus concentrations ranged from 7.1 ng/g to 71.2 ng/g and correlated with blood concentrations (r = 0.6). Mouse and human mean skin concentrations were in a similar range. Our data suggests that tacrolimus measurements in the blood may be used to approximate tacrolimus concentrations in the skin of kidney transplant recipients, and further exploited for the delivery of anti-cancer therapies designed to antagonize the immunosuppressive effects of tacrolimus in the skin.

Local blockade of tacrolimus promotes T-cell-mediated tumor regression in systemically immunosuppressed hosts

BACKGROUND

Immunosuppressive drugs such as tacrolimus have revolutionized our ability to transplant organs between individuals. Tacrolimus acts systemically to suppress the activity of T-cells within and around transplanted organs. However, tacrolimus also suppresses T-cell function in the skin, contributing to a high incidence of skin cancer and associated mortality and morbidity in solid organ transplant recipients. Here, we aimed to identify a compound capable of re-establishing antitumor T-cell control in the skin despite the presence of tacrolimus.

METHODS

In this study, we performed time-resolved fluorescence resonance energy transfer to identify molecules capable of antagonizing the interaction between tacrolimus and FKBP12. The capacity of these molecules to rescue mouse and human T-cell function in the presence of tacrolimus was determined in vitro, and the antitumor effect of the lead compound, Q-2361, was assessed in "regressor" models of skin cancer in immunosuppressed mice. Systemic CD8 T-cell depletion and analyses of intratumoral T-cell activation markers and effector molecule production were performed to determine the mechanism of tumor rejection. Pharmacokinetic studies of topically applied Q-2361 were performed to assess skin and systemic drug exposure.

RESULTS

Q-2361 potently blocked the interaction between tacrolimus and FKBP12 and reversed the inhibition of the nuclear factor of activated T cells activation by tacrolimus following T-cell receptor engagement in human Jurkat cells. Q-2361 rescued T-cell function in the presence of tacrolimus, rapamycin, and everolimus. Intratumoral injection of Q-2361-induced tumor regression in mice systemically immune suppressed with tacrolimus. Mechanistically, Q-2361 treatment permitted T-cell activation, proliferation, and effector function within tumors. When CD8 T cells were depleted, Q-2361 could not induce tumor regression. A simple solution-based Q-2361 topical formulation achieved high and sustained residence in the skin with negligible drug in the blood.

CONCLUSIONS

Our findings demonstrate that the local application of Q-2361 permits T-cells to become activated driving tumor rejection in the presence of tacrolimus. The data presented here suggests that topically applied Q-2361 has great potential for the reactivation of T-cells in the skin but not systemically, and therefore represents a promising strategy to prevent or treat skin malignancies in immunosuppressed organ transplant recipients.

Immunomodulators for Non-Melanoma Skin Cancers: Updated Perspectives

Non-melanoma skin cancers (NMSCs) are the most common cancers worldwide and may be associated with significant morbidity and mortality, especially in immunosuppressed populations. Successful management of NMSC must take primary, secondary and tertiary prevention strategies into consideration. In response to an improved understanding of the pathophysiology of NMSC and associated risk factors, multiple systemic and topical immunomodulatory drugs have been developed and integrated into clinical practice. Many of these drugs are efficacious in the prevention and treatment of precursor lesions (actinic keratoses; AKs), low-risk NMSC, and advanced disease. The identification of patients at high risk for the development of NMSC is critical in reducing disease morbidity. Understanding the various treatment options available and their comparative effectiveness is paramount for developing a personalized treatment regimen for such patients. This review article provides an updated overview of the various topical and systemic immunomodulatory drugs available for the prevention and treatment of NMSC, and the published data supporting their use in clinical practice.

Pharmacological Agents Used in the Prevention and Treatment of Actinic Keratosis: A Review

Actinic keratosis (AK) is among the most commonly diagnosed skin diseases with potentially life-threatening repercussions if left untreated. Usage of pharmacologic agents represents one of many therapeutic strategies that can be used to help manage these lesions. Ongoing research into these compounds continues to change our clinical understanding as to which agents most benefit particular patient populations. Indeed, factors such as past personal medical history, lesion location and tolerability of therapy only represent a few considerations that clinicians must account for when prescribing appropriate treatment. This review focuses on specific drugs used in either the prevention or treatment of AKs. Nicotinamide, acitretin and topical 5-fluorouracil (5-FU) continue to be used with fidelity in the chemoprevention of actinic keratosis, although some uncertainty persists in regard to which agents should be used in immunocompetent vs. immunodeficient/immunosuppressed patients. Topical 5-FU, including combination formulations with either calcipotriol or salicylic acid, as well as imiquimod, diclofenac and photodynamic light therapy are all accepted treatment strategies employed to target and eliminate AKs. Five percent of 5-FU is regarded as the most effective therapy in the condition, although the literature has conflictingly shown that lower concentrations of the drug might also be as effective. Topical diclofenac (3%) appears to be less efficacious than 5% 5-FU, 3.75-5% imiquimod and photodynamic light therapy despite its favorable side effect profile. Finally, traditional photodynamic light therapy, while painful, appears to be of higher efficacy in comparison to its more tolerable counterpart, daylight phototherapy.

Characterizing Skin Cancer in Transplant Recipients by Fitzpatrick Skin Phototype

INTRODUCTION

Nearly half of organ transplants occur annually in patients with Fitzpatrick skin phototypes (Fitz type) III-VI. Organ transplant recipients (OTRs) are at risk for sequelae of chronic immunosuppression, of which skin cancer is common. As literature regarding skin cancer risk is largely conducted in OTRs with Fitz types I and II, we aimed to further characterize the incidence and risk factors for skin cancer in OTRs with higher Fitz types.

METHODS

We conducted a retrospective review of OTRs with Fitz types III-VI evaluated by dermatology between 1 January 2012 and 1 June 2022. The primary outcome of this study was development of skin cancer post-transplant. Secondary outcomes included risk factors for skin cancer development. Data were analyzed using two-sample t-tests and Pearson's chi-squared.

RESULTS

Of 530 OTRs, 193 had Fitz type III or higher. Ten patients (5.18%) developed 87 skin cancers and one recurrence at a mean of 5.17 years posttransplant. Patients with skin cancer self-identified as Black (70%, p-value ≤ 0.001), male (70%, p-value ≤ 0.001), and kidney transplant recipients (70%, p-value ≤ 0.001), with a mean age of 58.20 years at transplant (p-value ≤ 0.001). Subjects with skin cancer were more likely to be former smokers (60%) and prescribed tacrolimus (p-value ≤ 0.001 each). Development of cutaneous squamous cell carcinoma (66, 75.86%) was most common, followed by basal cell carcinoma (17, 19.54%), and malignant melanoma (3, 3.45%). Skin cancer most often occurred on the face or scalp (60%, p-value = 0.027), though also developed in sun-protected sites (30%, p-value = 0.002). Verruca vulgaris was present in 10% of patients (p-value = 0.028).

CONCLUSIONS

Risk factors for skin cancer post-transplant differ in OTRs with higher Fitz types. Our results suggest that among OTRs who self-identified as Black, kidney recipients are at increased risk for skin cancer in non-sun-exposed regions. These cancers may be associated with human papillomavirus (HPV). Education is key for preventing morbidity and mortality secondary to skin cancer.

Non-melanoma skin cancers: physio-pathology and role of lipid delivery systems in new chemotherapeutic treatments

Non-melanoma carcinoma has high incidence rates and has two most common subtypes: basal cell carcinoma and squamous cell carcinoma. This type of carcinoma is usually not fatal; however, it can destroy sensory organs such as the nose, ears, and lips. The treatment of these injuries using non-invasive methods is thus strongly recommended. Some treatments for non-melanoma carcinoma are already well defined, such as surgery, cryosurgery, curettage and electrode section, and radiotherapy; however, these conventional treatments cause inflammation and scarring. In the non-surgical treatment of non-melanoma carcinoma, the topical administration of chemotherapeutic drugs contributes for an effective treatment with reduced side effects. However, the penetration of anticancer drugs in the deeper layers of the skin is required. Lipid delivery systems (liposomes, solid lipid nanoparticles, nanostructured lipid carriers) have been developed to overcome epidermal barrier of the skin and to allow the drugs to reach tumor cells. These lipid nanoparticles contribute to control the release profile of the loaded chemotherapeutic drugs, maintaining their stability and increasing death of tumor cells. In this review, the characteristics of non-melanoma carcinoma will be discussed, describing the main existing treatments, together with the contribution of lipid delivery systems as an innovative approach to increase the effectiveness of topical therapies for non-melanoma carcinomas.

Human Variation in DNA Repair, Immune Function, and Cancer Risk

DNA damage constantly threatens genome integrity, and DNA repair deficiency is associated with increased cancer risk. An intuitive and widely accepted explanation for this relationship is that unrepaired DNA damage leads to carcinogenesis due to the accumulation of mutations in somatic cells. But DNA repair also plays key roles in the function of immune cells, and immunodeficiency is an important risk factor for many cancers. Thus, it is possible that emerging links between inter-individual variation in DNA repair capacity and cancer risk are driven, at least in part, by variation in immune function, but this idea is underexplored. In this review we present an overview of the current understanding of the links between cancer risk and both inter-individual variation in DNA repair capacity and inter-individual variation in immune function. We discuss factors that play a role in both types of variability, including age, lifestyle, and environmental exposures. In conclusion, we propose a research paradigm that incorporates functional studies of both genome integrity and the immune system to predict cancer risk and lay the groundwork for personalized prevention.

Lymphocyte subsets and Langerhans cells in the skin of kidney transplant recipients under three different immunosuppressive regimens

BACKGROUND

Renal transplant recipients (RTRs) are at increased risk of developing skin cancer; however, the role of immunosuppression is not yet fully understood. In this study, we evaluated the immunohistochemical changes in the skin of RTRs under three different immunosuppression regimens: mTOR inhibitors (mTORi), sirolimus or everolimus, mycophenolic acid (MPA) precursors such as mycophenolate sodium or mofetil, or azathioprine (AZA).

METHODS

We evaluated biopsies of sun-exposed and sun-protected skin for immunohistochemical quantification of B lymphocytes (CD20+), T lymphocytes (CD3+, CD4+, and CD8+), and Langerhans cells (LCs) (CD1a+) in 30 RTRs and 10 healthy controls. The RTRs were divided into three groups: mTORi (n = 10), MPA (n = 10), and AZA (n = 10).

RESULTS

No differences were observed in the number of B lymphocytes. However, a significant decrease in the number of T lymphocytes and LCs was observed in both sun-protected and sun-exposed skin in the AZA and MPA groups, although to a lesser degree in the latter group. The skin of the mTORi group did not differ from that of the control group in terms of the number of B and T lymphocytes and LCs.

CONCLUSIONS

Patients treated with mTORi exhibit preserved cellular elements related to cutaneous immune surveillance. The use of AZA induced a greater degree of skin immunosuppression than in the control group, as demonstrated by the decrease in T lymphocytes and LCs.

Skin Cancers and Lung Transplant

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.

IFN-γ Critically Enables the Intratumoural Infiltration of CXCR3+ CD8+ T Cells to Drive Squamous Cell Carcinoma Regression

Simple Summary

Cutaneous squamous cell carcinoma (SCC) is prevalent in aged individuals and individuals with compromised or weakened immune systems, indicating a close association between immune function and SCC control. The aim of our study was to uncover the identity of key immune subsets that mediate SCC control, and to elucidate the mechanistic role of the proinflammatory cytokine Interferon-gamma in this process. We established a SCC regressor model, which we used to determine that: (1) CD8⁺ T cells, not CD4⁺ T cells or NK cells, are essential for SCC regression; (2) the neutralisation of Interferon-gamma prevents CD8⁺ T cell infiltration and SCC regression; (3) CD8⁺ T cell migration into SCC critically depends upon Interferon-gamma-induced chemokine expression. Thus, our model can be used to understand the key immune mechanisms involved in SCC regression, which will support targeted investigations into the integrity of these mechanisms in patients with progressive disease.

Abstract

Ultraviolet (UV) radiation-induced tumours carry a high mutational load, are highly immunogenic, and often fail to grow when transplanted into normal, syngeneic mice. The aim of this study was to investigate factors critical for the immune-mediated rejection of cutaneous squamous cell carcinoma (SCC). In our rejection model, transplanted SCC establish and grow in mice immunosuppressed with tacrolimus. When tacrolimus is withdrawn, established SCC tumours subsequently undergo immune-mediated tumour rejection. Through the depletion of individual immune subsets at the time of tacrolimus withdrawal, we established a critical role for CD8⁺ T cells, but not CD4⁺ T cells, γδ T cells, or NK cells, in driving the regression of SCC. Regression was critically dependent on IFN-γ, although IFN-γ was not directly cytotoxic to SCC cells. IFN-γ-neutralisation abrogated SCC regression, significantly reduced CD8⁺ T cell-infiltration into SCC, and significantly impaired the secretion of CXCL9, CXCL10 and CCL5 within the tumour microenvironment. A strong positive correlation was revealed between CXCL10 expression and CD8⁺ T cell abundance in tumours. Indeed, blockade of the CXCL10 receptor CXCR3 at the time of tacrolimus withdrawal prevented CD8⁺ T cell infiltration and the regression of SCC. Chimeric models revealed an important role for immune cells as producers of IFN-γ, but not as recipients of IFN-γ signals via the IFN-γ receptor. Together, these findings suggest a key role for IFN-γ in driving the expression of chemokines within the tumour environment essential for the destruction of established SCC by CD8⁺ T cells.

Recurrent squamous cell carcinoma in a post cardiac transplant patient

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Patient having recurrent carcinomas following heart transplant due to possible immunosuppression.

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Early Cancer surveillance in transplant patients is necessary to detect and treat malignancies early.

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Unique in having two recurrences post-transplant.

Introduction and importance

Solid organ transplantation has evolved along with dramatic advancements in definitive treatment for irreversible and uncompensated organ failure. Transplanted organ survival has improved as a result of reduced allograft rejection. However, negative long-term outcomes which were largely due to the adverse effects of rapidly evolving immunosuppressive regimens are still evident. The emergence of malignancies following prolonged exposure to immunosuppression treatment has affected the quality of life in transplant recipients. They are approximately one hundred times more likely to develop squamous cell carcinoma (SCC) compared to the general population and the incidence of malignant melanomas, basal cell carcinomas, and Kaposi’s sarcomas are also on the rise. The incidence of de novo malignancies ranges from 9 to 21% and is commonly seen in the skin and the lymphoreticular system in these patients.

Case presentation

A 78-year-old male presented with a lump in the right axilla, which had grown in size over a 4-week period. Patient had received a cardiac transplant 9 years prior and was on a regimen of Tacrolimus and Mycophenolate Mofetil since then.

Clinical discussion

Following 4 years of immunosuppression therapy, the patient developed a non-healing ulcer on his right forearm and the biopsy confirmed SCC. The recent biopsy performed on the new axillary lump also confirmed SCC. Iatrogenic immune suppressive treatment is associated with the occurrence of de novo, non-melanoma skin cancers in the solid organ transplant recipients and this necessitates early and comprehensive cancer surveillance models to be included in the pre and post-transplant assessment.

Conclusion

Advances in immunology suggest that peripheral blood mononuclear cell sequencing and immune profiling to identify immune phenotypes associated with keratinocyte cancers allow us to recognize patients who are more susceptible for SCC following organ transplantation and immunosuppression.

Evidence of BK Polyomavirus Infection in Urothelial but not Renal Tumors from a Single Center Cohort of Kidney Transplant Recipients

Emerging evidence indicates that reactivation of BK polyomavirus (BKPyV) in the kidney and urothelial tract of kidney transplant recipients (KTRs) may be associated with cancer in these sites. In this retrospective study of a single center cohort of KTRs (n = 1307), 10 clear cell renal cell carcinomas and 5 urinary bladder carcinomas were analyzed from 15 KTRs for the presence of BKPyV infection through immunohistochemistry and fluorescent in situ hybridization (FISH). Three of these patients had already exhibited biopsy-proven polyomavirus-associated nephropathies (PyVAN). Although the presence of BKPyV large-T antigen was evident in the urothelium from a kidney removed soon after PyVAN diagnosis, it was undetectable in all the formalin-fixed and paraffin-embedded (FFPE) blocks obtained from the 10 kidney tumors. By contrast, large-T antigen (LT) labeling of tumor cells was detected in two out of five bladder carcinomas. Lastly, the proportion of BKPyV DNA-FISH-positive bladder carcinoma nuclei was much lower than that of LT-positive cells. Taken together, our findings further strengthen the association between BKPyV reactivation and cancer development in KTRs, especially bladder carcinoma.

Twenty-eight-year incidence and characteristics of post-transplant skin cancers: Comparative analysis of past and recent 10-year experience

Because primary skin cancers in organ transplant recipients are rare, little is known about the characteristics and risk factors for skin cancers in organ transplant recipients. We searched the Asan Medical Center database of 13 469 organ transplant recipients for cases of all skin cancers from January 1990 to December 2018. Characteristics of and risk factors for skin cancers were analyzed and compared according to the period of transplantation. Of the identified 113 patients with skin cancers, squamous cell carcinoma was the most common cancer followed by basal cell carcinoma and Kaposi sarcoma. The cumulative incidence of skin cancers at 28 years was 5.3%. Over the 10-year period from January 2009 to December 2018, the standardized incidence ratio for premalignant in situ skin lesions increased, whereas the standardized incidence ratio for skin cancers decreased. Age at transplantation and treatment with more than two immunosuppressive agents were risk factors for the development of new skin cancers in organ transplant recipients. Over the most recent 10-year period, post-transplant skin cancers have been found earlier and diversified compared with in the previous period.

Cytokine/chemokine profiles in squamous cell carcinoma correlate with precancerous and cancerous disease stage

Actinic Keratosis (AK), Intraepidermal Carcinoma (IEC), and Squamous Cell Carcinoma (SCC) are generally considered to be advancing stages of the same disease spectrum. However, while AK often regress spontaneously, and IEC often regress in response to immune-activating treatments, SCC typically do not regress. Therefore, it is vital to define whether fundamental immunological changes occur during progression to SCC. Here we show that proinflammatory cytokine expression, chemokine expression, and immune cell infiltration density change during progression to SCC. Our findings suggest a switch from predominantly proinflammatory cytokine production to chemokine production is a key feature of progression from precancer to cancer. Together, these observations propose a model that can underpin current research and open new avenues of exploration into the clinical significance of these profiles with respect to immunotherapeutic or other treatment outcomes.

Primary squamous cell carcinoma of the peristomal skin of gastrostomy in a transplant patient: a first case report

Gastrostomy is commonly used to provide enteral nutrition when patient require a nutrition support due to not enough oral eating. Gastrostomy tube can lead to many complications; squamous cell carcinoma (SCC) is an extremely rare complication of the site of gastrostomy, it was described after several years of enteral nutrition or as part of a metastasis of head and neck tumors. We describe the case of a 60-year-old man heart-liver transplanted for hereditary amyloidosis. He required the setting of a gastrostomy-tube for enteral feeding and developed after only 18 months a SCC on the site of gastrostomy confirmed in the histologic report. The increased risk of SCC in transplant patients is due to immunosuppressive therapies, even though everolimus could reduce this risk. The pose of a gastrostomy is responsible of a chronic cutaneous inflammation, which is another risk factor for SCC. In these immunocompromised patients, gastrostomy or other chronic skin injury requires special monitoring, especially if the wound does not heal.

Homeostasis, regeneration and tumour formation in the mammalian epidermis

The epidermis is the outer covering of the skin and provides a protective interface between the body and the environment. It is well established that the epidermis is maintained by stem cells that self-renew and generate differentiated cells. In this review, we discuss how recent technological advances, including single cell transcriptomics and in vivo imaging, have provided new insights into the nature and plasticity of the stem cell compartment and the differing roles of stem cells in homeostasis, wound repair and cancer.

The Role of the Immune System in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer. In immunosuppressed populations it is a source of considerable morbidity and mortality due to its enhanced recurrence and metastatic potential. In common with many malignancies, leucocyte populations are both protective against cancer development and also play a role in 'sculpting' the nascent tumor, leading to loss of immunogenicity and tumor progression. UV radiation and chronic viral carriage may represent unique risk factors for cSCC development, and the immune system plays a key role in modulating the response to both. In this review, we discuss the lessons learned from animal and ex vivo human studies of the role of individual leucocyte subpopulations in the development of cutaneous SCC. We then discuss the insights into cSCC immunity gleaned from studies in humans, particularly in populations receiving pharmacological immunosuppression such as transplant recipients. Similar insights in other malignancies have led to exciting and novel immune therapies, which are beginning to emerge into the cSCC clinical arena.

Bacillus anthracis Protective Antigen Shows High Specificity for a UV Induced Mouse Model of Cutaneous Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) accounts for the majority of non-melanoma skin cancer related deaths, particularly in immunosuppressed persons. Identification of biomarkers that could be used to identify or treat SCC would be of significant benefit. The anthrax toxin receptors, Tumor Endothelial Marker 8 (TEM8) and Capillary Morphogenesis Gene 2 (CMG2), are endothelial receptors involved in extracellular matrix homeostasis and angiogenesis that are selectively upregulated on numerous tumors. One method of targeting these receptors is Protective Antigen (PA), a protein produced by B. anthracis that mediates binding and translocation of anthrax toxins into cells. PA targeted toxins have been demonstrated to selectively inhibit tumor growth and angiogenesis, but tumor selectivity of PA is currently unknown. In this work fluorescently labeled PA was shown to maintain receptor dependent binding and internalization in vitro. Utilizing a human papillomavirus transgenic mouse model that develops cutaneous SCC in response to ultraviolet irradiation we identified tumor uptake of PA in vivo. The intravenously administered PA resulted in tumor specific localization, with exclusive tumor detection 24 h post injection. Ex vivo analysis identified significantly higher fluorescence in the tumor compared to adjacent healthy tissue and major clearance organs, demonstrating low non-specific uptake and rapid clearance. While both TEM8 and CMG2 were observed to be overexpressed in SCC tumor sections compared to control skin, the intravenously administered PA was primarily co-localized with TEM8. These results suggest that PA could be systemically administered for rapid identification of cutaneous SCC, with potential for further therapeutic development.

A Novel mTORC1/2 Inhibitor (MTI-31) Inhibits Tumor Growth, Epithelial-Mesenchymal Transition, Metastases, and Improves Antitumor Immunity in Preclinical Models of Lung Cancer

PURPOSE

We aimed to investigate efficacy and mechanism of MTI-31 (LXI-15029), a novel mTORC1/mTORC2 inhibitor currently in human trial (NCT03125746), in non-small cell lung cancer (NSCLC) models of multiple driver mutations and tyrosine kinase inhibitor (TKI)-resistance.

EXPERIMENTAL DESIGN

Gene depletion, inhibitor treatment, immunological, flow cytometry, cellular, and animal studies were performed to determine in vitro and in vivo efficacy in NSCLC models of driver mutations and elucidate roles by mTOR complexes in regulating migration, epithelial-mesenchymal transition (EMT), metastasis, intracranial tumor growth, and immune-escape.

RESULTS

MTI-31 potently inhibited cell proliferation (IC₅₀ <1 μmol/L) and in vivo tumor growth in multiple NSCLC models of EGFR/T790M, EML4-ALK, c-Met, or KRAS (MED <10 mg/kg). In EGFR-mutant and/or EML4-ALK-driven NSCLC, MTI-31 or disruption of mTORC2 reduced cell migration, hematogenous metastasis to the lung, and abrogated morphological and functional traits of EMT. Disruption of mTORC2 inhibited EGFR/T790M-positive tumor growth in mouse brain and prolonged animal survival correlating a diminished tumor angiogenesis and recruitment of IBA1+ microglia/macrophages in tumor microenvironment. MTI-31 also suppressed programmed death ligand 1 (PD-L1) in EGFR- and ALK-driven NSCLC, mediated in part by mTORC2/AKT/GSK3β-dependent proteasomal degradation. Depletion of mTOR protein or disruption of mTOR complexes profoundly downregulated PD-L1 and alleviated apoptosis in Jurkat T and primary human T cells in a tumor-T cell coculture system.

CONCLUSIONS

Our results highlight mTOR as a multifaceted regulator of tumor growth, metastasis, and immune-escape in EGFR/ALK-mutant and TKI-resistant NSCLC cells. The newly characterized mechanisms mediated by the rapamycin-resistant mTORC2 warrant clinical investigation of mTORC1/mTORC2 inhibitors in patients with lung cancer.

Signaling Molecules in Posttransplantation Cancer

Immunosuppression is essential to prevent graft rejection. However, immunosuppression impairs the ability of the host immune system to control viral infection and decreases tumor immunosurveillance. Therefore, immunosuppression after organ transplantation is a major risk factor for posttransplantation cancer. Notably, recent reports suggest that immunosuppressive agents can activate tumorigenic pathways independent of the involvement of the host immune system. In this review, we focus on cell-intrinsic tumorigenic pathways directly activated by immunosuppressive agents and discuss the much-described infection- and immune-mediated mechanisms of cancer development in organ transplant recipients.

Ruxolitinib inhibits cyclosporine-induced proliferation of cutaneous squamous cell carcinoma

Organ transplant recipients (OTRs) on cyclosporine A (CSA) are prone to catastrophic cutaneous squamous cell carcinoma (SCC). Allograft-sparing, cancer-targeting systemic treatments are unavailable. We have shown increased risk for catastrophic SCC in OTRs via CSA-mediated induction of IL-22. Herein, we found that CSA drives SCC proliferation and tumor growth through IL-22 and JAK/STAT pathway induction. We in turn inhibited SCC growth with an FDA-approved JAK1/2 inhibitor, ruxolitinib. In human SCC cells, the greatest proliferative response to IL-22 and CSA treatment occurred in nonmetastasizing lines. IL-22 treatment upregulated JAK1 and STAT1/3 in A431 SCC cells. JAK/STAT pathway genes were highly expressed in tumors from a cohort of CSA-exposed OTRs and in SCC with high risk for metastasis. Compared with immunocompetent SCC, genes associated with innate immunity, response to DNA damage, and p53 regulation were differentially expressed in SCC from OTRs. In nude mice engrafted with human A431 cells, IL-22 and CSA treatment increased tumor growth and upregulated IL-22 receptor, JAK1, and STAT1/3 expression. Ruxolitinib treatment significantly reduced tumor volume and reversed the accelerated tumor growth. CSA and IL-22 exacerbate aggressive behavior in SCC. Targeting the IL-22 axis via selective JAK/STAT inhibition may reduce the progression of aggressive SCC in OTRs, without compromising immunosuppression.

Skin Cancer Following Solid Organ Transplantation: A Review of Risk Factors and Models of Care

The number of solid organ transplants has been increasing annually worldwide. Advances in transplantation surgery and community awareness of organ donation have been key contributors. Combined with increased understanding of immunosuppression, there are a growing number of solid organ transplant recipients in the community as a result of improved long-term outcomes. There remains a high incidence of deaths worldwide post-transplant due to non-melanoma skin cancer (NMSC), which has greater morbidity and mortality in this population than in the general community. Many transplant candidates are not screened prior to organ transplantation and not followed up dermatologically after transplant. After a comprehensive review of the MEDLINE database, we present an update of literature on risk factors for melanoma and non-melanoma skin cancer development in transplant recipients. Medications used by transplant recipients, including immunosuppressants and antibiotics, are discussed along with their respective risks of skin cancer development. We conclude with evidence-based recommendations for models of care, including patient education and dermatological review of transplant recipients.

Clinically-Relevant Rapamycin Treatment Regimens Enhance CD8+ Effector Memory T Cell Function In The Skin and Allow their Infiltration into Cutaneous Squamous Cell Carcinoma

Patients receiving immunosuppressive drugs to prevent organ transplant rejection exhibit a greatly increased risk of developing cutaneous squamous cell carcinoma (SCC). However, not all immunosuppressive drugs confer the same risk. Randomised, controlled trials demonstrate that switching renal transplant recipients receiving calcineurin inhibitor-based therapies to mammalian target of rapamycin (mTOR) inhibitors results in a reduced incidence of de novo SSC formation, and can even result in the regression of pre-existing premalignant lesions. However, the contribution played by residual immune function in this setting is unclear. We examined the hypotheses that mTOR inhibitors promote the enhanced differentiation and function of CD8⁺ memory T cells in the skin. Here, we demonstrate that the long-term oral administration of rapamycin to achieve clinically-relevant whole blood drug target thresholds, creates a "low rapamycin dose" environment in the skin. While both rapamycin and the calcineurin inhibitor tacrolimus elongated the survival of OVA-expressing skin grafts, and inhibited short-term antigen-specific CD8⁺ T cell responses, rapamycin but not tacrolimus permitted the statistically significant infiltration of CD8⁺ effector memory T cells into UV-induced SCC lesions. Furthermore, rapamycin uniquely enhanced the number and function of CD8⁺ effector and central memory T cells in a model of long-term contact hypersensitivity provided that rapamycin was present during the antigen sensitization phase. Thus, our findings suggest that patients switched to mTOR inhibitor regimens likely experience enhanced CD8⁺ memory T cell function to new antigen-challenges in their skin, which could contribute to their lower risk of de novo SSC formation and regression of pre-existing premalignant lesions.

Etiology of increased cancer incidence after solid organ transplantation

Over the past decades, there has been an encouraging increase in survival after solid organ transplantation. However, with longer life spans, more transplant recipients are at risk of dying with functioning grafts from illnesses such as cancer and cardiovascular conditions. Malignancy has emerged as an important cause of death in transplant recipients and is expected to become the leading cause of death in transplanted patients within the next decade. While it is known that solid organ transplant recipients have a three to five-fold increased risk of developing cancer compared with the general population, the mechanisms that lead to the observed excess risk in transplant recipients are less clear. This review explores the etiology of the increased cancer incidence in solid organ transplant including the effect of immunosuppressants on immunosurveillance and activation of oncogenic viruses, and carcinogenic effects of these medications; the role of chronic stimulation of the immune system on the development of cancer; and the impact of pre-existing cancer risk factors and factors related to end-stage organ disease on the cancer excess incidence in solid organ transplant recipients.

The pathogenesis of cutaneous squamous cell carcinoma in organ transplant recipients

The pathogenesis of keratinocyte carcinoma following organ transplantation is multifactorial, and recent evidence suggests a complex and often synergistic interplay between the carcinogenic effects of ultraviolet radiation, compromised immune surveillance, direct pro- and anticarcinogenic effects of drugs, oncogenic viruses (in particular, beta-genus human papillomaviruses) and host genetic susceptibility factors. We present an overview of those factors for which there is currently the most convincing evidence and highlight important gaps in our knowledge. In particular, a clear understanding of the interdependence and relative contributions of these co-factors is currently lacking, yet has important implications for rational development of clinically relevant biomarkers and targeted strategies for treatment and prevention of post-transplant keratinocyte cancers.

Sirolimus Increases T-Cell Abundance in the Sun Exposed Skin of Kidney Transplant Recipients

BACKGROUND

Kidney transplant recipients (KTRs) receiving the mammalian target of rapamycin inhibitor sirolimus may display a reduced risk of skin cancer development compared to KTRs receiving calcineurin inhibitors. Despite studies investigating the effects of these 2 drug classes on T cells in patient blood, the effect these drugs may have in patient skin is not yet known.

METHODS

Fifteen patients with chronic kidney disease (not recipients of immunosuppressive drugs), and 30 KTRs (15 receiving a calcineurin inhibitor, and 15 receiving sirolimus) provided matched samples of blood, sun exposed (SE) and non-SE skin. The abundance of total CD8⁺ and CD4⁺ T cells, memory CD8⁺ and CD4⁺ T cells, and regulatory T (Treg) cells in each sample was then assessed by flow cytometry.

RESULTS

Sirolimus treatment significantly increased absolute numbers of CD4⁺ T cells, memory CD8⁺- and CD4⁺ T cells, and Treg cells in SE skin versus paired samples of non-SE skin. No differences were found in the absolute number of any T cell subset in the blood. Correlation analysis revealed that the percentage of T cell subsets in the blood does not always accurately reflect the percentage of T-cell subsets in the skin of KTRs. Furthermore, sirolimus significantly disrupts the balance of memory CD4⁺ T cells in the skin after chronic sun exposure.

CONCLUSIONS

This study demonstrated that immunosuppressive drug class and sun exposure modify the abundance of multiple T-cell subsets in the skin of KTRs. Correlation analysis revealed that the prevalence of Treg cells in KTR blood does not accurately reflect the prevalence of Treg cells in KTR skin.

Phosphoinositide 3-Kinase-Dependent Signalling Pathways in Cutaneous Squamous Cell Carcinomas

Cutaneous squamous cell carcinoma (cSCC) derives from keratinocytes in the epidermis and accounts for 15–20% of all cutaneous malignancies. Although it is usually curable by surgery, 5% of these tumours metastasise leading to poor prognosis mostly because of a lack of therapies and validated biomarkers. As the incidence rate is rising worldwide it has become increasingly important to better understand the mechanisms involved in cSCC development and progression in order to develop therapeutic strategies. Here we discuss some of the evidence indicating that activation of phosphoinositide 3-kinases (PI3Ks)-dependent signalling pathways (in particular the PI3Ks targets Akt and mTOR) has a key role in cSCC. We further discuss available data suggesting that inhibition of these pathways can be beneficial to counteract the disease. With the growing number of different inhibitors currently available, it would be important to further investigate the specific contribution of distinct components of the PI3Ks/Akt/mTOR pathways in order to identify the most promising molecular targets and the best strategy to inhibit cSCC.

Enhanced Tumor Control with Combination mTOR and PD-L1 Inhibition in Syngeneic Oral Cavity Cancers

Significant subsets of patients with oral cancer fail to respond to single-agent programmed death (PD) blockade. Syngeneic models of oral cancer were used to determine if blocking oncogenic signaling improved in vivo responses to PD-L1 monoclonal antibody (mAb). Anti-PD-L1 enhanced durable primary tumor control and survival when combined with mTOR (rapamycin), but not in combination with MEK inhibition (PD901) in immunogenic MOC1 tumors. Conversely, PD-L1 mAb did not enhance tumor control in poorly immunogenic MOC2 tumors. Rapamycin enhanced expansion of peripheral antigen-specific CD8 T cells and IFNγ production following ex vivo antigen stimulation. More CD8 T cells infiltrated and were activated after PD-L1 mAb treatment in mice with immunogenic MOC1 tumors, which were stable or increased by the addition of rapamycin, but suppressed when PD901 was added. Rapamycin increased IFNγ production capacity in peripheral and tumor-infiltrating CD8 T cells. In vivo antibody depletion revealed a CD8 T-cell-dependent, and not NK cell-dependent mechanism of tumor growth inhibition after treatment with rapamycin and PD-L1 mAb, ruling out significant effects from NK cell-mediated antibody-dependent cellular cytotoxicity. Rapamycin also enhanced IFNγ or PD-L1 mAb treatment-associated induction of MHC class I expression on MOC1 tumor cells, an effect abrogated by depleting infiltrating CD8 T cells from the tumor microenvironment. These data conflict with traditional views of rapamycin as a universal immunosuppressant, and when combined with evidence of enhanced antitumor activity with the combination of rapamycin and PD-L1 mAb, suggest that this treatment combination deserves careful evaluation in the clinical setting. Cancer Immunol Res; 4(7); 611-20. ©2016 AACR.

[Malignancies of the skin and immunomodulatory antirheumatic therapy]

For the clinical practice there is uncertainty as to what degree the therapeutic immunomodulation of rheumatoid arthritis (RA) is associated with a weakening of protective tumor immunity. Neoplasms of the skin in particular are known to exhibit increased incidence rates in association with therapeutic immunosuppression in transplantation medicine; however, the immunosuppression required for the prevention of allogenic graft rejection is much more intensive and thus not directly transferable to the potential risks for an onset or relapse of melanoma or non-melanoma skin cancers (NMSC), e. g. spinocellular and basal cell carcinomas in association with the antirheumatic treatment of RA. This review covers the association of RA and its pharmacotherapy with conventional synthetic (cs) and biologic disease-modifying antirheumatic drugs (DMARD) on the basis of a systematic literature search. The incidence rates of NMSC are twice as high in biologic-naive RA patients compared to the general population, whereas the respective incidence rates for melanoma do not differ. A biologic treatment with tumor necrosis factor (TNF) blockers compared with administration of csDMARD only has a minor, if any effect on the increase of NMSC risk but is associated with a trend towards an elevated incidence rate of new onset melanoma although significance level was not reached in all of the reviewed studies. The data on non-TNF blocking biologics is sparse. Accordingly, it is inappropriate to draw any strong conclusions on potentially associated skin cancer risks from the present lack of safety signals. The consideration of individual risk factors, recommendations on sufficient UV protection and regular skin monitoring may serve to improve the safety of DMARD therapy in RA.

Cutaneous Squamous Cell Carcinomas in Organ Transplant Recipients

Non-melanoma skin cancers represent a major cause of morbidity after organ transplantation. Squamous cell carcinomas (SCC) are the most common cutaneous malignancies seen in this population, with a 65-100 fold greater incidence in organ transplant recipients compared to the general population. In recent years, human papillomaviruses (HPV) of the beta genus have been implicated in the pathogenesis of post-transplant SCCs. The underlying mechanism of carcinogenesis has been attributed to the E6 and E7 proteins of HPV. Specific immunosuppressive medications, such as the calcineurin inhibitors and azathioprine, are associated with a higher incidence of post-transplant SCCs compared to other immunosuppressive agents. Compared to other immunosuppressives, mTOR inhibitors and mycophenolate mofetil have been associated with a decreased risk of developing post-transplant non-melanoma skin cancers. As a result, they may represent ideal immunosuppressive medications in organ transplant recipients. Treatment options for post-transplant SCCs include surgical excision, Mohs micrographic surgery, systemic retinoid therapy, adjunct topical therapy, electrodessication and curettage, and radiation therapy. This review will discuss the epidemiology, risk factors, and management options of post-transplant SCCs. In addition, the underlying mechanisms of beta-HPV mediated carcinogenesis will be discussed.