Diverse landscape of dermatologic toxicities from small-molecule inhibitor cancer therapy

Cutaneous adverse reactions resulting from targeted cancer therapies: histopathologic and clinical findings

Targeted cancer treatments-designed to interfere with specific molecular signals responsible for tumor survival and progression-have shown benefit over conventional chemotherapies but may lead to diverse cutaneous adverse effects. This review highlights clinically significant dermatologic toxicities and their associated histopathologic findings, resulting from various targeted cancer drugs. Case reports and series, clinical trials, reviews, and meta-analyses are included for analysis and summarized herein. Cutaneous side effects resulting from targeted cancer therapies were reported with incidences as high as 90% for certain medications, and reactions are often predictable based on mechanism(s) of action of a given drug. Common and important reaction patterns included: acneiform eruptions, neutrophilic dermatoses, hand-foot skin reaction, secondary cutaneous malignancies, and alopecia. Clinical and histopathologic recognition of these toxicities remains impactful for patient care.

Gene expression profiling and multiplex immunofluorescence analysis of bullous pemphigoid immune-related adverse event reveal upregulation of toll-like receptor 4/complement-induced innate immune response and increased density of TH 1 T-cells

BACKGROUND

Immune checkpoint inhibitor (ICI)-based cancer therapies cause a variety of cutaneous immune-related adverse events (irAEs) including immunobullous skin eruptions like bullous pemphigoid (BP). However, little is known about the underlying immunopathogenic drivers of these reactions, and understanding the unique gene expression profile and immune composition of BP-irAE remains a critical knowledge gap in the field of oncodermatology/oncodermatopathology.

METHODS

BP-irAE (n = 8) and de novo BP control (n = 8) biopsy samples were subjected to gene expression profiling using the NanoString® Technologies nCounter PanCancer Immune Profiling Panel. Multiplex immunofluorescence (mIF) studies using markers for T-cells (CD3 and CD8), T helper 1 (T_H 1) cells (Tbet), T_H 2 cells (Gata3), T_H 17 cells (RORγT), and regulatory T-cells (Tregs; FoxP3) were further evaluated using InForm® image analysis.

RESULTS

Compared with de novo BP controls, BP-irAE samples exhibited upregulation of 30 mRNA transcripts (p < 0.025), including toll-like receptor 4 (TLR4) and genes associated with complement activation, and downregulation of 89 mRNA transcripts (p < 0.025), including genes associated with T_H 2, T_H 17, and B-cell immune response. BP-irAE demonstrated a greater density of Tbet⁺ (T_H 1) cells in the dermis (p = 0.004) and fewer Tregs in the blister floor (p = 0.028) when compared with that of de novo control BP samples.

CONCLUSIONS

BP-irAE exhibited activation of the TLR4/complement-driven classical innate immune response pathway, with dermal T_H 1 immune cell polarization and decreased Tregs in the blister floor. TLR/complement signaling may underlie the immunopathogenesis of BP-irAE.

The diverse landscape of dermatologic toxicities of non-immune checkpoint inhibitor monoclonal antibody-based cancer therapy

BACKGROUND

Since their first approval 25 years ago, monoclonal antibodies (mAbs) have become important targeted cancer therapeutics. However, dermatologic toxicities associated with non-immune checkpoint inhibitor (non-ICI) mAbs may complicate the course of cancer treatment. Data on the incidence and types of these reactions are limited.

METHODS

A comprehensive review was conducted on dermatologic toxicities associated with different classes of non-ICI mAbs approved for treatment of solid tumors and hematologic malignancies. The review included prospective Phase 1, 2, and 3 clinical trials; retrospective literature reviews; systematic reviews/meta-analyses; and case series/reports.

RESULTS

Dermatologic toxicities were associated with several types of non-ICI mAbs. Inflammatory reactions were the most common dermatologic toxicities, manifesting as maculopapular, urticarial, papulopustular/acneiform, and lichenoid/interface cutaneous adverse events (cAEs) with non-ICI mAbs. Immunobullous reactions were rare and a subset of non-ICI mAbs were associated with the development of vitiligo cAEs.

CONCLUSION

Dermatologic toxicities of non-ICI mAbs are diverse and mostly limited to inflammatory reactions. Awareness of the spectrum of the histopathologic patterns of cAE from non-ICI mAbs therapy is critical in the era of oncodermatology and oncodermatopathology.

Bosutinib-Induced Stevens-Johnson Syndrome and Evidence of Tolerance to a Structurally Dissimilar Tyrosine Kinase Inhibitor

Bosutinib is a breakpoint cluster region-Abelson gene (BCR-ABL) tyrosine kinase inhibitor (TKI) used for the treatment of chronic myeloid leukemia (CML). Patients on TKIs may develop severe cutaneous adverse reactions (SCARs). A 73-year-old female with CML treated with a second-generation TKI (bosutinib) was evaluated after developing fever and a maculopapular exanthema with skin-peeling affecting her lips, oral mucosa, and genitals 10 days after starting the medication. She required hospitalization, bosutinib discontinuation, and management with intravenous corticosteroids and antibiotics. Patch testing was contraindicated due to the severity of the reaction. The patient was subsequently challenged with first-generation TKI along with careful observation without any adverse reactions. She has not reported any adverse reactions while on therapy in the last two years. In patients who have suffered from SCARs, the suspected triggers must be avoided in all instances. In some cases, the underlying condition limits the use of alternative agents, but low-concentration patch testing may help guide alternative therapies within the same medication group. There appears to be a low cross-reactivity among generational TKIs, and our patient benefited from treatment with a structurally dissimilar alternative TKI for her CML.