Psoriasis and psoriasiform reactions secondary to immune checkpoint inhibitors

Psoriasis and psoriatic arthritis following use of dostarlimab for endometrial cancer

Immune checkpoint inhibitors (ICIs) are associated with immune-related adverse events (irAEs), but psoriasis and psoriatic arthritis (PsA) after use of dostarlimab have not been reported. We present a woman who received dostarlimab for endometrial cancer and subsequently developed rash and polyarthralgia, diagnosed as overlapping palmoplantar pustular and plaque psoriasis with PsA. She was treated with discontinuation of dostarlimab, topical steroids, oral methylprednisolone and methotrexate. This case highlights phenotypic heterogeneity in cutaneous irAEs influenced by malignancy and ICI type and underscores the need for multidisciplinary care in treating irAEs. We review three current professional society guidelines for managing irAEs, highlighting their emphasis on management based on severity grading, early initiation of systemic corticosteroids and steroid-sparing agents and discontinuation of ICI for severe events. Certain recommendations deviate from typical approaches to idiopathic rheumatologic disease. Further research is needed to support the ongoing development of approaches to irAE management.

A systematic review and meta-analysis of observational studies and uncontrolled trials reporting on the use of checkpoint blockers in patients with cancer and pre-existing autoimmune disease

BACKGROUND

Cancer patients with autoimmune disease have been excluded from randomized trials of immune checkpoint blockers (ICBs). We conducted a systematic review of observational studies and uncontrolled trials including cancer patients with pre-existing autoimmune disease who received ICBs.

METHODS

We searched 5 electronic databases through November 2023. Study selection, data collection, and quality assessment were performed independently by 2 investigators. We performed a meta-analysis to pool incidence of immune-related adverse events (irAEs), including de novo events and flares of existing autoimmune disease, hospitalizations due to irAEs, as well as deaths.

RESULTS

A total of 95 studies were included (23,897 patients with cancer and preexisting autoimmune disease). The most common cancer evaluated was lung cancer (30.7 %) followed by skin cancer (15.7 %). Patients with autoimmune disease were more likely to report irAEs compared to patients without autoimmune disease (relative risk 1.3, 95 % CI 1.0 to 1.6). The pooled occurrence rate of any irAEs (flares or de novo) was 61 % (95 % CI 54 % to 68 %); that of flares was 36 % (95 % CI 30 % to 43 %), and that of de novo irAEs was 23 % (95 % CI 16 % to 30 %). Flares were mild (grade <3) in half of cases and more commonly reported in patients with psoriasis/psoriatic arthritis (39 %), inflammatory bowel disease (37 %), and rheumatoid arthritis (36 %). 32 % of the patients with irAEs required hospitalization and treatment of irAEs included corticosteroids in 72 % of the cases. The irAEs mortality rate was 0.07 %. There were no statistically significant differences in cancer response to ICBs between patients with and without autoimmune disease.

CONCLUSIONS

Although more patients with pre-existing autoimmune disease had irAEs, these were mild and managed with corticosteroids in most cases, with no impact on cancer response. These results suggest that ICBs can be used in these patients, but careful monitoring is required, as over a third of the patients will experience a flare of their autoimmune disease and/or require hospitalization. These findings provide a crucial foundation for oncologists to refine their monitoring and management strategies, ensuring that the benefits of ICB therapy are maximized while minimizing its risks.

[Translated article] Recommendations from the Spanish Academy of Dermatology and Venereology Psoriasis Working Group on the Management of Patients with Cancer and Psoriasis

Several studies suggest that patients with psoriasis have a higher incidence of neoplasms, especially of the skin, which could be associated with the use of therapies to treat psoriasis. Furthermore, the evidence available on the safety profile of some treatments in this context, and the management of these patients is scarce, which is why clinical practice guidelines with recommendations on the management of psoriasis in cancer patients are ambiguous. This study provides recommendations on the management and use of the therapies currently available for these patients. They are the result of a Delphi consensus reached by 45 dermatologists of the Spanish Academy of Dermatology and Venereology Psoriasis Working Group, and their goal is to help specialists in the field in their decision-making processes.

Recommendations from the Spanish Academy of Dermatology and Venereology Psoriasis Working Group on the Management of Patients with Cancer and Psoriasis

Several studies suggest that patients with psoriasis have a higher incidence of neoplasms, especially of the skin, which could be associated with the use of therapies to treat psoriasis. Furthermore, the evidence available on the safety profile of some treatments in this context, and the management of these patients is scarce, which is why clinical practice guidelines with recommendations on the management of psoriasis in cancer patients are ambiguous. This study provides recommendations on the management and use of the therapies currently available for these patients. They are the result of a Delphi consensus reached by 45 dermatologists of the Spanish Academy of Dermatology and Venereology Psoriasis Working Group, whose goal is to help specialists in the field in their decision-making processes.

Psoriasis in the Era of Targeted Cancer Therapeutics: A Systematic Review on De Novo and Pre-existing Psoriasis in Oncologic Patients Treated with Emerging Anti-neoplastic Agents

New advancements in medicine have paved the way for targeted therapies and immune checkpoint inhibitors (ICIs), which have become mainstays of cancer therapy. Targeted therapies work by pinpointing specific molecules in cancer pathways and inhibiting their function, while ICIs target irregularities in the immune system and DNA repair, participating in the induction of cell death. Although these agents have demonstrated great efficacy in treating a diverse set of cancers, they can frequently provoke serious dermatologic adverse effects. The side effects caused by an ICI are classified as immune-related adverse events since ICIs are immunomodulating, while the cutaneous side effects of targeted therapies are known as dermatologic adverse effects. Multiple studies have reported psoriasis and psoriasiform eruptions among the side effects observed in neoplastic patients receiving targeted therapies or ICIs. Psoriasis is an immune-mediated disease characterized by overactive T-cells and keratinocytes. To conduct this review, we retrieved 1363 studies from the PubMed database published between 2008 and 2023 using the terms "psoriasis" AND "cancer treatment." Many of these studies aimed to understand how patients with cancer receiving treatment may develop or even achieve psoriasis remission. Given that cancer and psoriasis involve a delicate balance between immune activation and suppression, ICIs and targeted therapies might produce varying effects. The aim of this review was to explore the relationship between psoriasis and cancer therapeutics while also highlighting the need to prioritize proper management of cutaneous side effects in neoplastic patients.

Immune Checkpoint Inhibitor-Induced Psoriasis: Diagnosis, Management, and a Review of Cases

Immune checkpoint inhibitors (ICIs) are effective antitumor agents but are associated with immune-related adverse events. ICI-induced psoriasis commonly presents in patients with a history of psoriasis but may occur de novo, and it has a significant physical and psychosocial impact. ICI-induced and non-ICI-induced psoriasis are likely mediated by similar cytokines, and similar treatments are employed. Topical treatment often suffices, and when needed, several systemic treatments appear to be effective without impacting antitumor response. Development of psoriasis may indicate a superior response to ICIs. Thus, recognition and management of ICI-induced psoriasis is essential to avoid ICI interruption and maximize therapeutic potential.

Cytokine release syndrome triggered by programmed death 1 blockade (sintilimab) therapy in a psoriasis patient: A case report

BACKGROUND

In recent years, immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy across diverse malignancies. Notably, in patients with advanced gastric cancer, the use of programmed death 1 (PD-1) blockade has significantly prolonged overall survival, marking a pivotal advancement comparable to the impact of Herceptin over the past two decades. While the therapeutic benefits of ICIs are evident, the increasing use of immunotherapy has led to an increase in immune-related adverse events.

CASE SUMMARY

This article presents the case of a patient with advanced gastric cancer and chronic plaque psoriasis. Following sintilimab therapy, the patient developed severe rashes accompanied by cytokine release syndrome (CRS). Fortunately, effective management was achieved through the administration of glucocorticoid, tocilizumab, and acitretin, which resulted in favorable outcomes.

CONCLUSION

Glucocorticoid and tocilizumab therapy was effective in managing CRS after PD-1 blockade therapy for gastric cancer in a patient with chronic plaque psoriasis.

Advances in Foxp3+ regulatory T cells (Foxp3+ Treg) and key factors in digestive malignancies

Foxp3+ regulatory T cells (Foxp3+ Treg) play a role in regulating various types of tumors, but uncertainty still exists regarding the exact mechanism underlying Foxp3+ Treg activation in gastrointestinal malignancies. As of now, research has shown that Foxp3+ Treg expression, altered glucose metabolism, or a hypoxic tumor microenvironment all affect Foxp3+ Treg function in the bodies of tumor patients. Furthermore, it has been demonstrated that post-translational modifications are essential for mature Foxp3 to function properly. Additionally, a considerable number of non-coding RNAs (ncRNAs) have been implicated in the activation of the Foxp3 signaling pathway. These mechanisms regulating Foxp3 may one day serve as potential therapeutic targets for gastrointestinal malignancies. This review primarily focuses on the properties and capabilities of Foxp3 and Foxp3+Treg. It emphasizes the advancement of research on the regulatory mechanisms of Foxp3 in different malignant tumors of the digestive system, providing new insights for the exploration of anticancer treatments.

Cutaneous Hypersensitivity Reactions to Immune Checkpoint Inhibitors

The introduction of immune checkpoint inhibitors (ICIs) has transformed the management of various malignancies. Alongside their therapeutic success, the widespread application of ICIs has unveiled a spectrum of immune-related adverse events (irAEs), most often affecting the skin. Cutaneous irAEs (cirAEs) encompass a range from common morbilliform and lichenoid rashes to more severe conditions such as bullous dermatoses and psoriasiform eruptions, each presenting distinct clinical challenges. Moreover, less common but clinically severe cutaneous reactions like toxic epidermal necrolysis have also been observed. cirAEs are frequently observed, with an incidence ranging from 37% to 70% for anti-cytotoxic T lymphocyte-associated antigen-4 antibodies and 17% to 40% for anti- programmed death-1/anti-programmed death ligand-1 antibodies. Recognizing the critical need for effective therapeutic strategies, this review carefully examines current approaches and guidelines for managing cirAEs.

A Case of Punctate Psoriasis Following Treatment with Cetuximab in a Patient with Metastatic Gastric Adenocarcinoma

Background

In contemporary times, malignancies characterized by metastatic growth have been subjected to innovative therapeutic approaches involving immunological agents known as Programmed Death Receptor 1 (PD-1) inhibitors. Notwithstanding their remarkable immunotherapeutic effectiveness, these treatments can give rise to undesirable immune-related effects. Sintilimab, a PD-1 inhibitor sanctioned for marketing by the Chinese National Medical Products Administration in 2018, has been associated with 51 reported cases of adverse reactions on the market, excluding psoriasis, up to the present moment.

Case Description

Herein, we report the clinical characteristics of a patient with metastatic gastric adenocarcinoma who developed guttate psoriasis after receiving Sintilimab. The patient was an elderly male presenting with papules varying in size from that of rice grains to soybeans, accompanied by scattered erythematous lesions across his body. Notably, an atypical Auspitz's sign was observed, wherein certain lesions were covered with a minimal amount of scale, coupled with reported persistent itching. The progression of the disease manifested within a span of one week.

Conclusion

PD1 inhibitors have been associated with the recurrence, exacerbation, or new onset of psoriasis. Consequently, a personal or family history of psoriasis is an essential risk factor that needs to be considered before PD1 inhibitor medication, which helps with the early diagnosis of psoriasis. Early diagnosis of new-onset guttate psoriasis poses challenges. An early consultation with a dermatologist is recommended, and a conclusive diagnosis can be obtained through a histopathologic examination.

Literature analysis of cutaneous adverse reactions induced by tislelizumab

OBJECTIVE

Tislelizumab may induce immune-related adverse events, especially adverse skin events. Early detection and timely intervention of cutaneous adverse events are crucial to improve patients' quality of life and reduce the disruption of therapeutic regimens. This study aimed to determine the clinical characteristics of cutaneous adverse reactions to tislelizumab and offer a reference for its rational clinical use.

METHODS

Case reports of cutaneous adverse reactions induced by tislelizumab were collected from the relevant databases (up to 31 March 2023). Patient age, sex, primary disease, medication use, occurrence of adverse skin conditions, treatment, and outcomes were recorded and descriptively analysed.

RESULTS

A total of 13 patients were enrolled, including six males and seven females, aged 55-79 years, with a median age of 75 years and a mean age of 70.92 ± 8.84 years. The original disease was lung carcinoma in none patients, cervical carcinoma in two, and urothelial carcinoma and squamous cell carcinoma in one each. The time from the initiation of medication use to the occurrence of cutaneous adverse reactions ranged from 7 to 177 days. Among the 13 patients, 10 showed improvement after drug withdrawal or symptomatic treatment. Two patients died (one died of disease progression and multiorgan failure, one died of acute coronary syndrome), and one patient's adverse skin reactions persisted without treatment.

CONCLUSIONS

Tislelizumab-related cutaneous adverse reactions mostly occur after several days to months of treatment. In clinical practice, evaluation and monitoring should be strengthened. More attention should be paid to erythema and rashes, which may be signs of serious adverse skin reactions. Early detection and intervention can ensure the safe use of drugs and provide greater clinical benefits to patients.

Cutaneous immune-related adverse events to immune checkpoint inhibitors: from underlying immunological mechanisms to multi-omics prediction

The development of immune checkpoint inhibitors (ICIs) has dramatically altered the landscape of therapy for multiple malignancies, including urothelial carcinoma, non-small cell lung cancer, melanoma and gastric cancer. As part of their anti-tumor properties, ICIs can enhance susceptibility to inflammatory side effects known as immune-related adverse events (irAEs), in which the skin is one of the most commonly and rapidly affected organs. Although numerous questions still remain unanswered, multi-omics technologies have shed light into immunological mechanisms, as well as the correlation between ICI-induced activation of immune systems and the incidence of cirAE (cutaneous irAEs). Therefore, we reviewed integrated biological layers of omics studies combined with clinical data for the prediction biomarkers of cirAEs based on skin pathogenesis. Here, we provide an overview of a spectrum of dermatological irAEs, discuss the pathogenesis of this "off-tumor toxicity" during ICI treatment, and summarize recently investigated biomarkers that may have predictive value for cirAEs via multi-omics approach. Finally, we demonstrate the prognostic significance of cirAEs for immune checkpoint blockades.

Exacerbation of psoriasis induced by Nivolumab in a patient with stage IIIc gastric adenocarcinoma: A case report and literature review

Nivolumab, the programmed cell death 1 inhibitor, is a kind of immune checkpoint inhibitor commonly used to treat advanced cancers. Unfortunately, such drugs often induce various immune-related adverse events involving different body systems, with psoriasis being one of the skin toxicities. We report the clinical features of an exacerbated psoriasis induced by using nivolumab after three days in a patient with stage IIIc gastric adenocarcinoma. At the same time, we searched 27 case reports published from 2015 to 2021 over the world and systematically summarized the clinical manifestation of a total of 44 cases with psoriasis caused or exacerbated by Nivolumab. Commonly traditional treatment could be useful, and small molecule drugs such as apremilast are effective among some patients. However, more studies are needed to evaluate the efficacy and safety of biologics or small molecule drugs in treating psoriasis induced by nivolumab.

Mechanisms of dermatologic toxicities to immune checkpoint inhibitor cancer therapies

The discovery of immune checkpoint inhibition (ICI) sparked a revolution in the era of targeted anticancer therapy. While monoclonal antibodies targeting the CTLA-4 and PD-1 axes have improved survival in patients with advanced cancers, these immunotherapies are associated with a wide spectrum of dermatologic immune-related adverse events (irAEs). Several publications have addressed the clinical and histopathologic classification of these skin-directed irAEs, their impact on antitumor immunity and survival, and the critical role of supportive oncologic dermatology in their management. Here, we review the current understanding of the mechanistic drivers of immune-related skin toxicities with a focus on inflammatory, immunobullous, melanocyte/pigment-related reactions. We detail the specific immune-based mechanisms that may underlie different cutaneous reactions. We also discuss potential mechanisms as they relate to non-cutaneous irAEs and potential overlap with cutaneous irAEs, techniques to study differences in immune-related versus de novo skin reactions, and how treatment of these adverse events impacts cancer treatment, patient quality of life, and overall survival. An improved understanding of the mechanistic basis of cutaneous irAEs will allow us to develop and utilize blood-based biomarkers that could help ultimately predict onset and/or severity of these irAEs and to implement rational mechanistic-based treatment strategies that are targeted to the irAEs while potentially avoiding abrogating anti-tumor effect of ICIs.

High Grade Dermatologic Adverse Events Associated With Immune Checkpoint Blockade for Cancer

Immune checkpoint blockade (ICB) improves survival in many types of cancers including melanoma, non-small cell lung, renal cell, breast, and cervical cancers. However, many of these therapies are also associated with high grade dermatologic adverse events (DAEs), including Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN), SJS/TEN-like reactions, high grade maculopapular and psoriasiform rashes, autoimmune bullous eruptions, drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP), which may limit their tolerability and use. It is important to properly identify and treat DAEs to ICB because these DAEs may be associated with positive anti-tumor response and patients may have limited options for alternative anti-cancer therapeutics. In this review, we describe high grade DAEs to increasingly used ICB agents, which target CTLA-4 and PD-1 or its ligand, PD-L1 and enable the immune system to target cancer cells. We further differentiate life-threatening adverse reactions from mimickers and report cases of serious DAEs which have been recorded in association with ICB through the FDA Adverse Events Reporting System (FAERS), which is an archive of adverse events associated with various drugs and therapeutic biologic products reported voluntarily by consumers and healthcare professionals as well as mandatorily by manufacturers. Lastly, we summarize management recommendations for these adverse events and discuss knowledge and evidence gaps in this area.

Loss of epidermal Langerhans cells in psoriasiform lesions of de novo induced or worsened pre-existing psoriasis following uses of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICI), including monoclonal antibodies to programmed death 1, programmed death ligand 1, and cytotoxic T lymphocyte-associated antigen 4, have provided great therapeutic benefits for cancer patients at advanced stages. However, the introduction of ICI frequently results in the development of immune-related adverse events (irAE) through activation of autoreactive T cells. Here, we present three cases of cancer patients with cutaneous irAE, including development of de novo psoriasis and exacerbation of pre-existing psoriasis. Interestingly, these patients shared an altered histological feature characterized by loss of epidermal CD1a⁺ cells, namely Langerhans cells (LC), in the psoriasiform lesions in contrast to "conventional psoriasis" exhibiting unchanged or activated LC. A possible underlying mechanism was that ICI-mediated hyperactivation of effector T cells contributed to aggravation or establishment of psoriasis phenotype, which might be associated with direct cytotoxicity or expulsion of LC from the epidermis.

Clinical Treatment Study of Secondary Multiple Squamous Cell Carcinoma with Psoriasis Vulgaris

Dermatologic diseases are the fourth most frequent nonfatal common illness, yet they have a psychological, economical, and professional burden that is comparable to or larger than other chronic conditions. From a survey in China of 6 provinces, the overall prevalence of psoriasis with squamous cell carcinoma was 0.47%. According to the current investigation, the outburst of skin disease was not associated with gender, but mainly with the climate of the environment; that is, dry cold weather will more likely to induce psoriasis. Approximately 3% of people around the world have psoriasis, which is near the most common autoimmune skin disease in adults. By simple estimation, there are at least two hundred million psoriasis patients in the world. Therefore, it is not just a simple health problem in a country or a region but a serious global challenge. Of note, about half of the adult patients had been reported to be sick in their childhood and they mostly fell ill around 10 years old. Actinic keratosis is perhaps the most common, followed by squamous cell carcinoma and, to a lesser extent, acne vulgaris, psoriasis, and hidradenitis suppurativa, as well as dermatitis herpetiformis. 5-Fluorouracil (5-FU) 0.5 percent is used topically to treat actinic keratosis and squamous cell carcinoma with good outcomes, while it might cause significant toxicity in certain patients. Dapsone, a Valosin-containing protein, is a medication that is often used to treat inflammatory skin disorders like psoriatic arthritis, but it can occasionally cause hemolytic anemia. Furthermore, biologic medications for the treatment of moderate-to-severe psoriasis and multiple squamous cell carcinoma have proven to be successful and safe; nevertheless, a small percentage of patients do not react to biologic treatment in the long term or do not respond at all. Based on the data from the China Food and Drug Administration, the majority of chemical drugs are utilized as the topical formulations, while Chinese medicines are mainly delivered by an oral route, suggesting that the market for topical preparations of Chinese medicine to treat skin diseases like psoriasis is worth exploration. This large interindividual diversity in response could be caused by changes in genes that encode proteins implicated in the disease's pathologic environment or the medication's mechanism of action. Pharmacogenetics is the study of the association between genetic differences and medication response, which is valuable for identifying nonresponsive patients and those who are more likely to suffer toxicity as a result of treatment. This study highlights the pharmacogenetic recommendations for dermatology therapies that have the strongest evidence at this time, highlighting those that have been incorporated in clinical practice guides. Pharmacogenetic clinical guidelines for multiple squamous cell carcinoma and psoriasis vulgaris were found in this investigation. Here, for multiple squamous cell carcinoma trichohyalin-like 1 (TCHHL1), 5-fluorouracil (5-FU) 0.5% is recommended. Along with that dapsone, Valosin-containing protein can be recommended for treating the psoriasis vulgaris. We made some clinical trials over the two diseases, and from the result obtained, we hypothesize that the suggested drug may be a novel therapeutic target in treating the multiple squamous cell carcinoma with psoriasis vulgaris.

Prevalence of inverse psoriasis subtype with immune checkpoint inhibitors

Background

Cutaneous immune-related adverse events (irAEs) are the most common irAEs caused by immune-checkpoint inhibitors (ICI). Psoriasiform eruptions, both de novo and flares, may occur. Evidence is lacking on inverse psoriasis subtype.

Methods

A retrospective study was conducted at Dana-Farber Cancer Institute/Mass General Brigham through February 2020 using databases. Confirmed inverse psoriasis cases pre-/post-ICI initiation either independently or in conjunction with other psoriasis subtypes were included. Known psoriasis cases without flare post-ICI were excluded.

Results

A total of 262 (3%) individuals with any ICI-mediated psoriasiform cutaneous irAE were identified out of the 8683 DFCI ICI-treated patients. Of these, 13 (5% of psoriasis patients) had inverse psoriasis (mean age 68.7 years; 7/13 male sex). Median (range) time from ICI initiation to inverse psoriasis development or flare was 7 (4–12) and 3.5 (2–6) weeks, respectively. Pruritus occurred in 12/13 (92.30%) cases. 11 (85%) had inguinal involvement; other sites included gluteal cleft (6; 46%), inframammary (3; 23%), perianal (2; 15%), axilla (2; 15%), umbilicus (2; 15%), and infra-abdominal folds (1; 8%). Most (9/13) individuals had more than one site involved. The Common Terminology Criteria for Adverse Events severity was 1 in 10 (76.92%) individuals and 2 in 3 (15.38%) individuals. Six (46.15%) patients were treated initially by oncology with topical (nystatin, econazole, or clotrimazole) or systemic antifungals (fluconazole) for median (range) of 3.5 (1–7) months without improvement, for presumed candida intertrigo.

Conclusion

Patients on ICI may develop inverse psoriasis, which may be initially confused for fungal intertrigo. Delayed diagnosis can prolong symptoms, while patients are treated ineffectively with topical/systemic antifungals for presumed candida infection. Oncologist and dermatologist awareness is important to improve diagnosis of ICI-mediated inverse psoriasis, its management and affected patients’ quality of life.

Severe de novo pustular psoriasiform immune-related adverse event associated with nivolumab treatment for metastatic esophageal adenocarcinoma

Breakthrough targeted therapies have produced significant improvements in survival for cancer patients, but have a propensity to cause cutaneous immune-related adverse events (irAEs). Psoriasiform irAEs, representing about 4% of dermatologic toxicities associated with immune checkpoint inhibitor (ICI) therapy, are usually mild, occur in older patients and present as an exacerbation of existing psoriasis after several doses of ICI therapy. We report a case of a 58-year-old woman with metastatic esophageal adenocarcinoma and no prior history of psoriasis who developed a pustular psoriasiform irAE, beginning 3 days after initiation of nivolumab and progressing to confluent erythroderma with pustules over 2 weeks despite topical steroid use. She had concurrent acrodermatitis enteropathica, clinically diagnosed and confirmed with a low serum zinc level, that improved with supplementation. Her psoriasiform irAE was refractory to systemic steroids and acitretin, prompting discontinuation of nivolumab and treatment with ustekinumab and concomitant slow taper of acitretin and prednisone. Pustular psoriasiform irAE is a rare but severe dermatologic toxicity resulting from ICI therapy. Given the diverse morphologic types of cutaneous irAEs that can occur during ICI therapy, a clinical and histopathologic examination of dermatologic toxicities is critical to identify patients who may benefit from biologic therapy.

Immune Checkpoint Blockade and Skin Toxicity Pathogenesis

Immune checkpoint blockade has revolutionized the treatment of multiple tumor types, including melanoma and nonmelanoma skin cancers. The use of immune checkpoint blockade is curtailed by tissue toxicities termed immune-related adverse events (irAEs), which occur most quickly and most often in the skin. We review the rationale for immune checkpoint blockade use, current agents, use in skin cancers, autoimmune manifestations in the skin, and considerations for predictive biomarkers and treatment options on the basis of skin pathogenesis. We also highlight major gaps in the field and the lack of preclinical modeling in the skin. A deeper understanding of irAE pathophysiology may help to uncouple toxicity and efficacy but mandates an interdisciplinary approach, including foundational skin immunology and autoimmune pathogenesis.