Exploring Keratinocyte Carcinoma Models for Preclinical Treatment Evaluation

Martin Wiinberg Bardenfleth

Research output: Book/ReportPh.D. thesis

Abstract

Keratinocyte carcinoma arises in the keratinocytes of the skin and encompasses basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC). Keratinocyte carcinoma is the most common type of cancer and presents a major health and economical challenge for healthcare systems in the Western World. Current treatment options for inoperable cases of keratinocyte carcinoma are limited. In recent years, the approval of immune checkpoint inhibitors has marked a breakthrough in the treatment of keratinocyte carcinoma. This success has sparked renewed interest in developing new immunotherapies for keratinocyte carcinoma.
Mouse models play an irreplaceable role in the development of new treatments by providing a platform for evaluating therapeutic strategies and understanding treatment mechanisms. Despite the high prevalence of keratinocyte carcinoma, current mouse models of keratinocyte carcinoma are sparse and impractical to include in treatment evaluation studies due to their complexity or requirement of immunocompromised mice. This thesis presents the development and utilization of immunocompetent transplantable mouse models of keratinocyte carcinoma that mimic the current models but offer more practical models in preclinical drug development.
A transplantable model of BCC was established by serial passaging tumor cells in vivo from a well-established genetically engineered mouse model of BCC. Comparative analysis using histology, flow cytometry and RNA sequencing revealed that the transplantable BCC model resembled microscopic structures, immune cell populations and key transcriptional features of its parental genetically modified BCC model, while being more practical and resource efficient.
Building upon the same approach, a transplantable cSCC tumor model was established from an ultraviolet radiation-induced cSCC model. This cSCC model was utilized to evaluate the therapeutic potential of intratumoral resiquimod-gel (RSQ-gel), a toll-like receptor 7/8 agonist formulated into a sustained-release platform. The efficacy of the RSQ-gel was further compared with the clinically approved topical imiquimod cream treatment. Both treatments were evaluated alone and in combination with ablative fractional laser (AFL), a treatment previously shown to induce antitumor immune responses in preclinical studies. RSQ-gel treatment with adjuvant AFL demonstrated significant antitumor efficacy in the cSCC model. Additionally, the efficacy of weekly RSQ-gel was comparable to daily imiquimod treatment. This study highlights the utility of the transplantable cSCC model for initial preclinical evaluation of treatments for keratinocyte carcinoma.
AFL has been shown to induce both pro-inflammatory, antitumor immune responses in tumor models and anti-inflammatory, healing responses in skin tissue. To uncover the ambiguity of AFL immunological responses, AFL’s impact on macrophages was investigated as they play a key role in both pro-inflammatory anticancer responses and anti-inflammatory, healing responses. AFL treatment of healthy mouse skin polarized macrophages towards an anti-inflammatory wound-healing-like phenotype characterized by an upregulation of arginase-1 protein. These findings suggest that AFL treatment potentially induces anti-inflammatory response that could counteract the immune activation required for effective antitumor immune responses.
In summary, this thesis presents the development of transplantable keratinocyte carcinoma models that provide practical and representative platforms for preclinical development. The practical application of the developed transplantable keratinocyte carcinoma models was demonstrated in the included preclinical evaluation study. This thesis also discovered that anti-inflammatory responses that resemble wound-healing processes occur in skin in response AFL treatment.
Original languageEnglish
PublisherDTU Health Technology
Number of pages119
Publication statusPublished - 2024

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