Tumor Clearance and Immune Cell Recruitment in UV-Induced Murine Squamous Cell Carcinoma Exposed to Ablative Fractional Laser and Imiquimod Treatment

Laser-assisted topical delivery of vismodegib reduces hedgehog gene expression in human basal cell carcinomas in vivo

BACKGROUND

Systemically delivered hedgehog inhibitors including vismodegib and sonidegib are widely used to treat basal cell carcinomas (BCCs). Ablative fractional laser (AFL)-assisted topical delivery of vismodegib has been demonstrated in preclinical studies. The aim of this explorative clinical study was to evaluate intratumoral vismodegib concentrations and effect on hedgehog pathway gene expression following AFL-assisted topical vismodegib delivery to BCCs.

METHODS

In an open-label clinical trial, 16 nodular BCCs (in n = 9 patients) received one application of CO2 -AFL (40 mJ/microbeam, 10% density) followed by topical vismodegib emulsion. After 3-4 days, vismodegib concentrations in tumor biopsies (n = 15) and plasma were analyzed and compared with samples from patients receiving oral treatment (n = 3). GLI1, GLI2, PTCH1, and PTCH2 expression was determined by quantitative polymerase chain reaction (n = 7) and GLI1 additionally by in situ hybridization (n = 3).

RESULTS

Following AFL-assisted topical administration, vismodegib was detected in 14/15 BCCs and reached a median concentration of 6.2 µmol/L, which compared to concentrations in BCC tissue from patients receiving oral vismodegib (9.5 µmol/L, n = 3, p = 0.8588). Topical vismodegib reduced intratumoral GLI1 expression by 51%, GLI2 by 55%, PTCH1 and PTCH2 each by 73% (p ≤ 0.0304) regardless of vismodegib concentrations (p ≥ 0.3164). In situ hybridization demonstrated that GLI1 expression was restricted to tumor tissue and downregulated in response to vismodegib exposure.

CONCLUSION

A single AFL-assisted topical application of vismodegib resulted in clinically relevant intratumoral drug concentrations and significant reductions in hedgehog pathway gene expressions.

Anti-PD-1 immunotherapy with adjuvant ablative fractional laser displays increased tumour clearance of squamous cell carcinoma, a murine study

PD-1 checkpoint inhibitors are used as systemic immunotherapy for locally advanced and metastatic cutaneous squamous cell carcinoma (SCC); however, improved treatment efficacy is urgently needed. In this study, we aimed to investigate the effect of combining systemic anti-PD-1 treatment with adjuvant ablative fractional laser (AFL) in a spontaneous SCC mouse model. Tumours induced by ultraviolet radiation in the strain C3.Cg-Hrhr /TifBomTac were divided into four groups: anti-PD-1-antibody+AFL (n = 33), AFL alone (n = 22) anti-PD-1-antibody alone (n = 31) and untreated controls (n = 46). AFL was given at Day 0 (100 mJ/mb, 5% density), while anti-PD-1-antibody (ip, 200 μg) at Days 0, 2, 4, 6 and 8. Response to treatment was evaluated by tumour growth, survival time and by dividing response to treatment into complete responders (clinically cleared tumours), partial responders (reduced tumour growth rate compared to untreated controls) and non-responders (no decrease in tumour growth rate compared to untreated controls). The strongest tumour response was observed following the combination of systemic anti-PD-1 treatment combined with laser exposure, resulting in the highest percentage of complete responders (24%) compared with untreated controls (0%, p < 0.01), AFL monotherapy (13%, p > 0.05) and anti-PD-1-antibody monotherapy (3%, p > 0.05). Moreover, all three treatment interventions demonstrated significantly reduced tumour growth rates compared with untreated controls (p < 0.01), and the mice had significantly longer survival times (p < 0.01). In conclusion, the combination treatment revealed an improved treatment effect that significantly enhanced the complete tumour clearance not observed with the monotherapies, indicating a possible additive effect of anti-PD-1 with adjuvant AFL in treatment of SCC.

Large area fractional laser treatment of mouse skin increases energy expenditure

Fractional laser (FL) treatment is a common dermatologic procedure that generates arrays of microscopic treatment zones separated by intact tissue, promoting fast wound healing. Using a mouse model, we introduced a large area fractional laser treatment (LAFLT) method to study metabolic effects. Using two laser modalities, ablative FL (AFL) and non-ablative FL (NAFL), and exposing different percentages of mice's total body surface area (TBSA), we followed changes in metabolic parameters in real time using metabolic cages. Additionally, body composition, markers of inflammation, neurohormonal signaling, and browning of adipocytes were investigated. LAFLT, especially in high TBSA groups, had specific metabolic effects such as significantly increased average daily energy expenditure, increased fat mass loss, systemic browning of adipocytes, and inflammatory states, without compromising other organs. The ability of LAFLT to stimulate metabolism in a controlled way could develop into a promising therapeutic treatment to induce positive metabolic changes that replace or augment systemic drugs.

Repeated exposure to fractional CO2 laser delays squamous cell carcinoma formation and prevents clinical and subclinical photodamage visualized by line-field confocal optical coherence tomography and histology

OBJECTIVES

Ablative fractional laser (AFL) is a well-established modality for treating ultraviolet radiation (UVR)-induced skin photodamage. We aimed to investigate the potential of AFL to delay squamous cell carcinoma (SCC) formation and prevent photodamage in a preclinical UVR-induced SCC model.

MATERIALS AND METHODS

Hairless C3.Cg-Hrhr /TifBomTac mice (n = 50) were exposed to UVR three times weekly throughout the study. UV-exposed mice were randomized to two groups that received dorsal CO2 AFL (10 mJ/mb, 10% density) or no treatment. AFL was performed every other week for a total of 16 weeks (nine treatments in total). The primary outcome was time to tumor occurrence. In a subset of mice on Day 150, prevention of clinical photodamage was assessed by examination of skin tightness and dyspigmentation. Concomitantly, assessment of subclinical photoprevention based on normalization of keratinocyte dysplasia, dermo-fiber morphology (collagen and elastin fibers), and skin thickness, was performed using line-field confocal optical coherence tomography (LC-OCT) and histology.

RESULTS

Repeated AFL treatments delayed SCC tumor development compared to UVR control mice by 12, 19, and 30 days for first, second, and third tumors, respectively (p ≤ 0.0017). Compared to UVR controls, AFL prevented photodamage both clinically and subclinically, based on LC-OCT and histology. In the epidermal layer, AFL imparted photopreventative effects including reduced dyspigmentation and keratinocyte dysplasia (1 vs. 2.5, p = 0.0079) and partial normalization of the epidermal thickness (p < 0.0001). In the dermis, AFL led to twofold greater skin tightness (p = 0.0079), improved dermo-fiber structure, and dermal thickness (p = 0.0011).

CONCLUSION

In conclusion, repeated AFL treatments of UVR-exposed skin significantly delayed SCC tumor formation and prevented clinical and imaging-assessed subclinical signs of photodamage, indicating a potential for AFL in prevention strategies for SCC and photodamage in high-risk populations.

A comparison of cancer vaccine adjuvants in clinical trials

Cancer treatment has come a long way in increasing overall survival; however, evasion of the immune system continues to be a challenge in treating individuals with established disease burdens. Due to the difficulty in stimulating an immune response against cancer, approaches utilizing combination adjuvants with different mechanisms may be beneficial. A combination of these adjuvants with other adjuvants or other treatments has demonstrated synergistic effects in the form of a robust and sustained immune response, demonstrating the importance of further development. This review discusses the intricacies of immune evasion, applications of adjuvants with different mechanisms of action, and adjuvants used for cancer immunotherapy in clinical trials.

Feasibility of Intratumoral Anti-PD1 as Treatment of Human Basal Cell Carcinoma: An Explorative Study with Adjuvant Ablative Fractional Laser

The use of immune checkpoint inhibitors (ICI) is expanding with the approval for advanced/metastatic keratinocyte carcinoma; however, most tumors are non-aggressive. Local administration could broaden ICI, but adequate immune response might require an immune-attractive adjuvant such as ablative fractional laser (AFL). Accordingly, this study aimed to explore intratumoral injection of anti-PD1 with and without AFL in basal cell carcinoma (BCC), exploring anti-PD1 concentration, immune cell infiltration, tumor response, and safety. This open-label, proof-of-concept trial investigated intratumoral anti-PD1 + AFL combination therapy versus anti-PD1 or AFL monotherapy in 28 BCC patients. The primary endpoints were immune cell infiltration evaluated immunohistochemically and clinical tumor response after 3 months. The secondary outcomes were tumoral drug concentration and safety. The most robust response was obtained following intervention with combined anti-PD1+AFL, leading to a ~2.5-fold increase in CD3+ cells (p = 0.027), and tumor reduction ≥25% in 73%, including two tumors with complete remission. Upon anti-PD1 monotherapy, a slight decrease in CD3+ cells was observed while a non-significant increase following AFL was seen. Tumor reduction ≥25% was seen in 45% and 50%, respectively, after anti-PD1 and AFL monotherapy. The CD8/CD3 ratio remained unchanged after anti-PD1+AFL and anti-PD1 monotherapy, while AFL led to a decreased ratio. A non-significant decline in the Foxp3/CD3 ratio was observed for all groups. Side-effects were mild with no systemic drug concentration detected. Intratumoral anti-PD1 injection is feasible, and a single exposure to locally injected anti-PD1 with adjuvant AFL increased immune cell infiltration and reduction in BCC with limited side-effects.

Neutrophils and their extracellular traps impair ablative fractional carbon dioxide laser-induced dermal remolding in mice

OBJECTIVES

Ablative fractional CO₂ laser (AFL) therapy is an effective intervention to induce dermal remodeling. AFL treatment of the skin triggers the recruitment of immune cells, with neutrophils dominating the early phase. However, the role of recruited neutrophils in AFL-induced microinjuries and their subsequent dermal remodeling capacity remains elusive.

MATERIALS AND METHODS

A mouse model of AFL-induced dermal remodeling was established. RNA sequencing was used to identify the prominent features of AFL-treated tissues. Histological analysis, including H&E and Masson staining, ultrastructure observation by transmission microscopy, immunofluorescence, and quantitative real-time polymerase chain reaction were used for dermal remodeling analysis. Moreover, AFL-treated mice were intraperitoneally injected with anti-mouse Ly6G antibodies to deplete neutrophils. Neutrophil extracellular traps (NETs) were explored using immunofluorescence, transmission microscopy, and in vitro coculture experiments.

RESULTS

Dermal remodeling, characterized by an increased number of CD31-positve vessels and elevated messenger RNA (mRNA) expression of genes encoding transforming growth factor-β (TGF-β), collagen I, and collagen III, was observed at 15 days after AFL treatment. In the AFL-induced inflammation phase, RNA sequencing identified neutrophil chemotaxis, and degranulation genes were significantly enriched. Histology and immunofluorescence staining of human and mouse tissues harvested at Day 1 after AFL treatment revealed significant neutrophil infiltration surrounding thermal-induced microinjuries. Neutrophil depletion decreased the expression of stress-related genes such as S100A8 and S100A9 in the early phase following AFL treatment. Importantly, neutrophil depletion enhanced dermal remodeling at Day 15, as reflected by enrichment of the extracellular matrix and collagen biosynthesis genes based on RNA sequencing. Moreover, increased collagen I, collagen III, and TGF-β mRNA expression, increased cell proliferation, and vascularity were observed. Interestingly, NETs, which could be induced by AFL-treated fibroblasts in vitro, were identified in both human and mouse tissues on Day 1 after AFL treatment.

CONCLUSIONS

AFL-treated human and mouse skin recruited a large number of neutrophils. The neutrophil surge impaired dermal remodeling in mice. The microenvironment and fibroblast functional modulation mediated by neutrophil degranulation and NET formation were determined to be the underlying mechanisms. Our results indicate that modification of infiltrated neutrophil activity might be a potential therapeutic target for AFL-induced dermal remodeling.

Anti-PD-1 Therapy with Adjuvant Ablative Fractional Laser Improves Anti-Tumor Response in Basal Cell Carcinomas

Simple Summary

In some mouse models, ablative fractional laser (AFL) enhances the efficacy of anti-programmed cell death1 therapy (aPD-1), which was recently approved for basal cell carcinoma (BCC). In this explorative study, we aimed to assess locally applied AFL as an adjuvant to systemic aPD-1 treatment in a clinically relevant BCC model. BCC-carrying mice received aPD-1 alone, AFL alone, aPD-1+AFL, or no treatment. Both aPD-1 and AFL alone significantly increased survival time relative to the untreated controls, while aPD-1 that had been complemented with AFL further promoted survival and improved tumor clearance and growth rates. The BCCs were poorly immune infiltrated, but aPD-1 with adjuvant AFL and AFL alone induced substantial immune cell infiltration in tumors and increased the levels of relevant immune cell subtypes. Thus, the anti-tumor response that was generated by aPD-1 with adjuvant AFL may potentially be promoted by increased immune activity in tumors. In conclusion, the use of a local AFL adjuvant to systemic aPD-1 therapy could hold substantial promise for BCC treatment.

Abstract

The efficacy of anti-programmedcelldeath1therapy (aPD-1), which was recently approved for basal cell carcinoma (BCC) treatment, can be enhanced by adjuvant ablative fractional laser (AFL) in syngeneic murine tumor models. In this explorative study, we aimed to assess locally applied AFL as an adjuvant to systemic aPD-1 treatment in a clinically relevant autochthonous BCC model. BCC tumors (n = 72) were induced in Ptch1^+/−K14-CreER2p53^fl/fl-mice (n = 34), and the mice subsequently received aPD-1 alone, AFL alone, aPD-1+AFL, or no treatment. The outcome measures included mouse survival time, tumor clearance, tumor growth rates, and tumor immune infiltration. Both aPD-1 and AFL alone significantly increased survival time relative to untreated controls (31 d and 34.5 d, respectively vs. 14 d, p = 0.0348–0.0392). Complementing aPD-1 with AFL further promoted survival (60 d, p = 0.0198 vs. aPD-1) and improved tumor clearance and growth rates. The BCCs were poorly immune infiltrated, but aPD-1 with adjuvant AFL and AFL alone induced substantial immune cell infiltration in the tumors. Similar to AFL alone, combined aPD-1 and AFL increased neutrophil counts (4-fold, p = 0.0242), the proportion of MHCII-positive neutrophils (p = 0.0121), and concordantly, CD4⁺ and CD8⁺ T-cell infiltration (p = 0.0061–0.0242). These descriptive results suggest that the anti-tumor response that is generated by aPD-1 with adjuvant AFL is potentially promoted by increased neutrophil and T-cell engraftment in tumors. In conclusion, local AFL shows substantial promise as an adjuvant to systemic aPD-1 therapy in a clinically relevant preclinical BCC model.

Laser Immunotherapy: A Potential Treatment Modality for Keratinocyte Carcinoma

Simple Summary

In light of expanding incidences of keratinocyte carcinoma (KC) with many patients developing multiple tumors, the demand for new treatment modalities is high. With the approval of cemplimab for locally advanced and metastasizing basal cell carcinoma and squamous cell carcinoma, KC is now included as an indication for systemic immunotherapy. At present, however, systemic KC therapy remains limited by the severe side effects associated with treatment. Immunotherapy might be more broadly applied if locally administered. Localized to the skin, KCs are easily accessible to topical drugs and physical interventions such as laser. There is an increasing appreciation of lasers’ potential to activate an immune response. Further enhancement of the laser-based immune activation might be obtained by combining laser and immunotherapeutic agents, known as laser immunotherapy. In search of new treatment modalities for KC and aiming to broaden the field of KC immunotherapy, this review discusses the current literature on immune activation following both laser monotherapy and laser immunotherapy.

Abstract

The role of the immune system in cancer growth is well recognized and the development of immunotherapy represents a breakthrough in cancer treatment. Recently, the use of systemic immunotherapy was extended to keratinocyte carcinoma (KC), specifically locally advanced and metastasizing basal and squamous cell carcinoma. However, since most KC lesions are non-aggressive, systemic treatment with associated side effects is rarely justified. Conversely, topical immunotherapy with imiquimod remains restricted to premalignant and superficial lesions. Use of laser in the treatment of KC has evolved from physical tumor destruction and laser-assisted drug delivery to laser-mediated immune modulation. Evidence indicates that laser monotherapy can lead to immune cell infiltration, tumor reduction and resistance to tumor re-inoculation. Combining laser with immunotherapeutic agents, termed laser immunotherapy (LIT), may further potentiate immune activation and tumor response. Studies on LIT show not only direct anti-tumor effects but systemic adaptive immunity, illustrated by the prevention of tumor recurrence and regression in distant untreated tumors. These findings imply a therapeutic potential for both local and metastatic disease. This work provides rationales for immune-based treatment of KC and presents the current status of KC immunotherapy. Aiming to expand the field of KC immunotherapy, the review discusses the literature on immune activation following laser monotherapy and LIT.