Regressed melanocytic nevi secondary to pembrolizumab therapy: an emerging melanocytic dermatologic effect from immune checkpoint antibody blockade

Cutaneous Toxicities in the Setting of Immune Checkpoint Blockade:: The Era of Oncodermatopathology

Advancements in cancer therapy with monoclonal immune checkpoint antibody blockade have impacted the practice of all medical specialties. Cutaneous immune-related adverse events (irAEs) are a frequent, unintended, off-target consequence of immune checkpoint inhibitor (ICI) therapy that have ushered in the era of oncodermatopathology. Knowledge of the diverse morphologic types of cutaneous irAEs from ICI therapy allows further classification of cutaneous irAEs according to major histopathologic reaction patterns. Early studies suggest that immune mechanisms of lichenoid dermatitis irAE, psoriasiform dermatitis irAE, and bullous pemphigoid irAE show some similarities and differences from their histopathologic counterparts not associated with ICI therapy.

Tertiary lymphoid structures with overlapping histopathologic features of cutaneous marginal zone lymphoma during neoadjuvant cemiplimab therapy are associated with antitumor response

The development of immune checkpoint inhibitor (ICI) therapy with anti-CTLA-4 and anti-PD-1/L1 monoclonal antibodies has led to a paradigm shift in cancer therapy. ICI neoadjuvant therapy followed by surgery has become the standard of care for several advanced-stage cancers. The pathology associated with ICI therapy is vast and includes neoadjuvant-associated tissue reactions and activation of tertiary lymphoid structures (TLSs) at the site of the tumor bed and off-target immune-related adverse events. TLSs are thought to recapitulate lymph node function and may act as localized immune machinery to mount an antitumor response. B-cell activation in TLSs during neoadjuvant ICI therapy has been correlated with antitumor response. We report a patient with a history of sarcomatoid squamous cell carcinoma treated with neoadjuvant ICI cemiplimab who developed clonal expansion of B-cells in the TLSs of the tumor bed. The TLSs morphologically mimicked a cutaneous marginal zone lymphoma with plasmacytic differentiation. Awareness of clonal expansion of B-cells in TLSs during neoadjuvant ICI therapy is critical to recognize a response to ICI therapy and to avoiding an incorrect diagnosis of low-grade B-cell lymphoma.

Dermatologic toxicities to immune checkpoint inhibitor therapy: A review of histopathologic features

Antineoplastic agents that use the immune system have revolutionized cancer treatment. Specifically, implementation of immune checkpoint inhibitors, monoclonal antibodies that block cytotoxic T-lymphocyte-associated antigen-4, programmed cell death protein 1, or programmed cell death ligand 1 show improved and sustained responses in patients with cancer. However, these agents are associated with a plethora of adverse events, many manifesting in the skin. As the clinical application of cancer immunotherapies expands, understanding the clinical and histopathologic features of associated cutaneous toxicities becomes increasingly important to dermatologists, oncologists, and pathologists to ensure timely diagnosis and appropriate care. This review discusses cutaneous reactions to immune checkpoint inhibitors, focusing on histopathologic features.

Pathology of immune-mediated tissue lesions following treatment with immune checkpoint inhibitors

Immune check point inhibitor (CPI) therapy has revolutionized treatment paradigms for several cancers, but at the cost of triggering a diverse spectrum of immune-mediated injury to non-cancer tissues. The complex biology of these toxicities remains incompletely understood, partly because tissue acquisition from affected areas can be challenging to retrieve, thus hindering development of targeted therapy. Here, we review the literature describing pathology of immune-mediated tissue lesions including gastrointestinal, skin, rheumatic, pulmonary, cardiac, renal and hepatic lesions and highlight key immunological insights.

Gene expression profiling of lichenoid dermatitis immune-related adverse event from immune checkpoint inhibitors reveals increased CD14+ and CD16+ monocytes driving an innate immune response

BACKGROUND

Cancer patients receiving antibodies abrogating immune checkpoint pathways may develop a diverse array of immune-related adverse events (irAEs), of which lichenoid dermatitis (LD) is the most common. The mechanism driving the emergence of these irAEs remain understudied, underscoring a critical need to determine the unique gene expression profiles and immune composition in LD-irAE.

METHODS

LD-irAE (n = 3) and benign lichenoid keratosis (BLK) control (n = 3) were profiled with NanoString nCounter PanCancer Immune Profiling Panel interrogating the mRNA levels of 770 genes. Immunohistochemical (IHC) studies (n = 14 samples) for CD14, CD16, T-Bet, Gata-3, and FoxP3 were further evaluated using Aperio digital image analysis.

RESULTS

The LD-irAE showed downregulation of 93 mRNA transcripts (P < 0.05) and upregulation of 74 mRNA transcripts (P < 0.04) including toll-like receptor (TLR) 2 and TLR4 (P < 0.05). CD14⁺ and CD16⁺ monocytes quantified by IHC (H-score) were higher in LD-irAE than in the BLK control (P < 0.05). The immune composition of LD-irAE exhibited higher numbers of T-Bet⁺ (Th1) cells compared with Gata-3⁺ (Th2) cells (P = 0.016) and lower numbers of FoxP3 (T regulatory) cells (P = 0.008).

CONCLUSIONS

LD-irAE exhibited activation of CD14/TLR innate immune response with increased CD14⁺ and CD16⁺ monocytes compared with BLK control. CD14/TLR signaling may drive the development of LD-irAE.

Suprabasal acantholytic dermatologic toxicities associated checkpoint inhibitor therapy: A spectrum of immune reactions from paraneoplastic pemphigus-like to Grover-like lesions

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

Granulomatous/sarcoid-like lesions associated with checkpoint inhibitors: a marker of therapy response in a subset of melanoma patients

BACKGROUND

Immune checkpoint therapy has dramatically changed the landscape of cancer therapy, providing an efficacious and durable therapeutic option for patients with advanced-stage disease. However, dermatologic toxicities are a well-recognized side effect in patients receiving this therapy. A spectrum of immune related adverse events (irAEs) involving the skin can occur and include immunobullous disorders, lichenoid dermatitis, and vitiligo. Granulomatous/sarcoid-like lesions are now being recognized with the current class of checkpoint inhibitors (CPIs) that involve the dermis, the subcutaneous tissue (panniculitis), and lymph nodes.

CASE PRESENTATION

We report 3 patients who developed granulomatous/sarcoid-like lesions while being treated with immune checkpoint therapy for advanced-stage melanoma, and we provide a comprehensive review of the literature in which similar cases are described. To date, 26 patients (including the 3 from this report) have been described with a median age of 57 years who developed granulomatous/sarcoid-like lesions associated with CPIs (median onset 6 months), of which 77% of patients had melanoma as primary tumor. To manage this adverse side effect, therapy was withheld in 38% of patients and 44% of the patients were treated with systemic steroids and 8% patients with localized therapy (one patient with intralesional triamcinolone). 96% of patients demonstrated either resolution or improvement of granulomatous/sarcoid-like lesions associated with CPIs irrespective of medical intervention. Therapeutic response, stable disease, or remission of primary malignancy was observed in 71% of reported patients who developed granulomatous/sarcoid-like lesions associated with CPIs over a median follow-up of 11.5 months since initiation of treatment.

CONCLUSIONS

The development of granulomatous/sarcoid-like lesions associated with CPIs is a recognized manifestation with the current class of immune checkpoint therapy that may clinically and radiographically mimic disease recurrence. Awareness of this type of toxicity is important for appropriate management and possible measurement of therapeutic response in a subset of patients who manifest this type of immune-mediated reaction.