Combination vismodegib and photodynamic therapy for multiple basal cell carcinomas

Treatment of nonmelanoma skin cancer with pro-differentiation agents and photodynamic therapy: Preclinical and clinical studies (Review)

Photodynamic therapy (PDT) is a nonscarring cancer treatment in which a pro-drug (5-aminolevulinic acid, ALA) is applied, converted into a photosensitizer (protoporphyrin IX, PpIX) which is then activated by visible light. ALA-PDT is now popular for treating nonmelanoma skin cancer (NMSC), but can be ineffective for larger skin tumors, mainly due to inadequate production of PpIX. Work over the past two decades has shown that differentiation-promoting agents, including methotrexate (MTX), 5-fluorouracil (5FU) and vitamin D (Vit D) can be combined with ALA-PDT as neoadjuvants to promote tumor-specific accumulation of PpIX, enhance tumor-selective cell death, and improve therapeutic outcome. In this review, we provide a historical perspective of how the combinations of differentiation-promoting agents with PDT (cPDT) evolved, including Initial discoveries, biochemical and molecular mechanisms, and clinical translation for the treatment of NMSCs. For added context, we also compare the differentiation-promoting neoadjuvants with some other clinical PDT combinations such as surgery, laser ablation, iron-chelating agents (CP94), and immunomodulators that do not induce differentiation. Although this review focuses mainly on the application of cPDT for NMSCs, the concepts and findings described here may be more broadly applicable towards improving the therapeutic outcomes of PDT treatment for other types of cancers.

Long-term strategies for management of advanced basal cell carcinoma with hedgehog inhibitors

Basal cell carcinoma (BCC), the most common type of skin cancer, is characterized by aberrant activation of the hedgehog molecular pathway. Systemic therapy is indicated when local approaches, such as surgery and radiation, are inappropriate. In this article, a group of clinical experts recommends the long-term management strategy for advanced BCC patients treated with systemic therapy. The hedgehog inhibitors sonidegib and vismodegib are first-line treatments for advanced BCC with a long-lasting response, but long-term treatment with hedgehog inhibitors is often challenged by tolerability issues. However, several strategies for adverse effect management are available, such as dose interruptions, on-label alternate-day dosing and supportive medications. In conclusion, although BCC shows a high tumor mutational burden that favors a response to immunotherapy, experts recommend keeping patients on hedgehog inhibitors limiting immunotherapy to those who developed resistance during hedgehog inhibitor therapy or in case of persisting toxicity despite long-term management of adverse events.

The current clinical approach to difficult-to-treat basal cell carcinomas

INTRODUCTION

Basal cell carcinoma (BCC) is the most common malignant tumor in adult white populations. If BCCs are not treated for years, if they cause massive destruction of the surrounding tissues, if they are considered unresectable or not eligible for radiotherapy they become progressively 'locally advanced' (laBCC) or metastatic (mBCC). These tumors are defined as 'difficult-to-treat BCC.'

AREAS COVERED

A comprehensive search on PubMed was conducted to identify relevant literature about the several approved and recommended treatment options for the management of difficult-to-treat BCC published from January 2012 to July 2022. Surgical options, radiotherapy, hedgehog inhibitors, immunotherapy, and combined treatments are discussed. The keywords used were basal cell carcinoma; difficult-to-treat BCC; management of difficult-to-treat BCC; surgical therapy; radiotherapy; hedgehog inhibitors; immunotherapy.

EXPERT OPINION

Identifying the best approach to DTT BCCs is one of the main challenges for the dermato-oncologist. The introduction of HHI for the treatment of advanced BCCs has revolutionized the clinical management of DTT BCCs. The immune checkpoint inhibitor cemiplimab has been approved for the treatment of locally advanced or metastatic BCC refractory to HHI therapy or in patients intolerant to HHI therapy. Multidisciplinary teams (MDTs) play a key role in managing these complex patients.

Increasing cancer permeability by photodynamic priming: from microenvironment to mechanotransduction signaling

The dense cancer microenvironment is a significant barrier that limits the penetration of anticancer agents, thereby restraining the efficacy of molecular and nanoscale cancer therapeutics. Developing new strategies to enhance the permeability of cancer tissues is of major interest to overcome treatment resistance. Nonetheless, early strategies based on small molecule inhibitors or matrix-degrading enzymes have led to disappointing clinical outcomes by causing increased chemotherapy toxicity and promoting disease progression. In recent years, photodynamic therapy (PDT) has emerged as a novel approach to increase the permeability of cancer tissues. By producing excessive amounts of reactive oxygen species selectively in the cancer microenvironment, PDT increases the accumulation, penetration depth, and efficacy of chemotherapeutics. Importantly, the increased cancer permeability has not been associated to increased metastasis formation. In this review, we provide novel insights into the mechanisms by which this effect, called photodynamic priming, can increase cancer permeability without promoting cell migration and dissemination. This review demonstrates that PDT oxidizes and degrades extracellular matrix proteins, reduces the capacity of cancer cells to adhere to the altered matrix, and interferes with mechanotransduction pathways that promote cancer cell migration and differentiation. Significant knowledge gaps are identified regarding the involvement of critical signaling pathways, and to which extent these events are influenced by the complicated PDT dosimetry. Addressing these knowledge gaps will be vital to further develop PDT as an adjuvant approach to improve cancer permeability, demonstrate the safety and efficacy of this priming approach, and render more cancer patients eligible to receive life-extending treatments.

Hedgehog Suppresses Paclitaxel Sensitivity by Regulating Akt-Mediated Phosphorylation of Bax in EGFR Wild-Type Non-Small Cell Lung Cancer Cells

Non-small cell lung cancer (NSCLC) is one of the most common and deadly cancers worldwide. Among NSCLC patients, almost half have wild-type epidermal growth factor receptor (EGFR WT). The primary therapeutic option for these EGFR WT NSCLC patients is chemotherapy, while NSCLC patients with EGFR mutations have more diverse therapeutic options, including EGFR tyrosine kinase inhibitors. Moreover, NSCLC patients with EGFR WT have worse chemotherapy response than EGFR mutant NSCLC patients. Thus, an urgent need exists for novel therapeutic strategies to improve chemotherapy response in EGFR WT NSCLC patients. Hedgehog signaling is known to be highly active in NSCLC; however, its potential role in chemoresistance is not fully understood. In the present study, we found that paclitaxel (PTX) treatment induces hedgehog signaling in EGFR WT NSCLC cells, and inhibition of hedgehog signaling with GDC-0449 (Vismodegib) increases sensitivity to PTX-stimulated apoptosis. Furthermore, GDC-0449 potentiates PTX-induced reactive oxygen species and mitochondrial dysfunction. In contrast, a hedgehog agonist, Hh-Ag1.5, attenuates PTX-induced apoptosis. Mechanistic experiments revealed that hedgehog induces phosphorylation of Akt at Ser473. Akt then phosphorylates Bax at Ser184, which can switch its activity from pro-apoptosis to anti-apoptosis. Taken together, our findings suggest that inhibition of hedgehog signaling might be a promising therapeutic strategy to improve PTX response in EGFR WT NSCLC.

The Hedgehog pathway and its inhibitors: Emerging therapeutic approaches for basal cell carcinoma

Basal cell carcinoma (BCC) is the most common non-melanoma skin cancer (NMSC). Although surgery is the first-line treatment, BCC can lead in some cases, to a metastatic or advanced form, requiring targeted combination therapies. The Hedgehog (Hh) signalling pathway is the major pathway associated with the formation of basal carcinoma tumorigenesis, thus, targeting this is a promising therapeutic approach. Some Hh inhibitors have been approved by the US Food and Drug Administration (FDA), such as vismodegib and sonidegib. However, both of these showed limited effectiveness against resistant tumors. Therefore, an essential understanding of the mechanisms involved in the Hh signaling pathway is necessary to improve tumor inhibition.

Outcomes of adjunctive therapies post hedgehog inhibitors in the management of locally advanced basal cell carcinoma: A systematic review and pooled analysis

Management of patients with locally advanced basal cell carcinoma (laBCC) with traditional strategies has yielded suboptimal outcomes. Targeted treatments including hedgehog inhibitor therapy (HHIT) present limitations when utilized as monotherapy. Herein, we report evidence-based outcomes from available literature on multimodality treatments adjuvant to HHIT in laBCC management. Utilizing a systematic search strategy in PubMed, we identified studies published from inception to April 15, 2020, screened for definitive inclusion/exclusion criteria, and performed individual study quality assessment and pooled analysis to assess impact of adjunctive treatment-based responses post-HHIT on clinical response and recurrence outcomes. Twenty-nine studies (n = 103) were included. Primary findings include a complete response (CR) rate of 90.5%, the median follow-up of 12 months post-HHIT completion. The recurrence rate was 10.8% with 12-month median time to recurrence. Mohs micrographic surgery (MMS) had 100% CR post-HHIT, while no difference was observed between surgery and radiation therapy (RT). MMS and surgery had comparable 2-year recurrence free rates (RFR) at 87% and 86% respectively, while RT had the lower 2-year RFR at 67%. Male gender portended a more advanced stage at diagnosis and worse outcomes. In a subset analysis, periorbital laBCCs with orbital involvement had a CR rate of 81.8% versus 100% in those without orbital involvement, with similar rates of recurrence. Limited available quantitative data and possible publication bias were limitations. Pooled analysis of observational data supports use of adjunctive therapies post-HHIT to improve treatment response in patients with laBCC. Longer-term follow-up is needed to study recurrence rates after combination therapy.

Switching Hedgehog inhibitors and other strategies to address resistance when treating advanced basal cell carcinoma

Although basal cell carcinoma (BCC) is often managed successfully with surgery, patients with locally advanced BCC (laBCC) or metastatic BCC (mBCC) who are not candidates for surgery or radiotherapy have limited treatment options. Most BCCs result from aberrant Hedgehog pathway activation in keratinocyte tumor cells, caused by sporadic or inherited mutations. Mutations in the patched homologue 1 gene that remove its inhibitory regulation of Smoothened homologue (SMO) or mutations in SMO that make it constitutively active, lead to Hedgehog pathway dysregulation and downstream activation of GLI1/2 transcription factors, promoting cell differentiation and proliferation. Hedgehog inhibitors (HHIs) block overactive signaling of this pathway by inhibiting SMO and are currently the only approved treatments for advanced BCC. Two small-molecule SMO inhibitors, vismodegib and sonidegib, have shown efficacy and safety in clinical trials of advanced BCC patients. Although these agents are effective and tolerable for many patients, HHI resistance occurs in some patients. Mechanisms of resistance include mutations in SMO, noncanonical cell identity switching leading to tumor cell resistance, and non-canonical pathway crosstalk causing Hedgehog pathway activation. Approaches to managing HHI resistance include switching HHIs, HHI and radiotherapy combination therapy, photodynamic therapy, and targeting Hedgehog pathway downstream effectors. Increasing understanding of the control of downstream effectors has identified new therapy targets and potential agents for evaluation in BCC. Identification of biomarkers of resistance or response is needed to optimize HHI use in patients with advanced BCC. This review examines HHI resistance, its underlying mechanisms, and methods of management for patients with advanced BCC.

Photodynamic Therapy and Hyperthermia in Combination Treatment-Neglected Forces in the Fight against Cancer

Cancer is one of the leading causes of death in humans. Despite the progress in cancer treatment, and an increase in the effectiveness of diagnostic methods, cancer is still highly lethal and very difficult to treat in many cases. Combination therapy, in the context of cancer treatment, seems to be a promising option that may allow minimizing treatment side effects and may have a significant impact on the cure. It may also increase the effectiveness of anti-cancer therapies. Moreover, combination treatment can significantly increase delivery of drugs to cancerous tissues. Photodynamic therapy and hyperthermia seem to be ideal examples that prove the effectiveness of combination therapy. These two kinds of therapy can kill cancer cells through different mechanisms and activate various signaling pathways. Both PDT and hyperthermia play significant roles in the perfusion of a tumor and the network of blood vessels wrapped around it. The main goal of combination therapy is to combine separate mechanisms of action that will make cancer cells more sensitive to a given therapeutic agent. Such an approach in treatment may contribute toward increasing its effectiveness, optimizing the cancer treatment process in the future.

Photodynamic Therapy for Basal Cell Carcinoma: The Clinical Context for Future Research Priorities

Photodynamic therapy (PDT) is an established treatment option for low-risk basal cell carcinoma (BCC). BCC is the most common human cancer and also a convenient cancer in which to study PDT treatment. This review clarifies challenges to researchers evident from the clinical use of PDT in BCC treatment. It outlines the context of PDT and how PDT treatments for BCC have been developed hitherto. The sections examine the development of systemic and subsequently topical photosensitizers, light delivery regimens, and the use of PDT in different patient populations and subtypes of BCC. The outcomes of topical PDT are discussed in comparison with alternative treatments, and topical PDT applications in combination and adjuvant therapy are considered. The intention is to summarize the clinical relevance and expose areas of research need in the BCC context, ultimately to facilitate improvements in PDT treatment.

Recent Advances in Self-Exciting Photodynamic Therapy

Photodynamic therapy (PDT) is already (Food and Drug Administration) FDA approved and used in the clinic for oncological treatment of pancreatic, lung, esophagus, bile duct, and of course several cancers of skin. It is an important tool in the oncological array of treatments, but for it exist several shortcomings, the most prominent of which is the shallow depth penetration of light within tissues. One-way researchers have attempted to circumvent this is through the creation of self-exciting "auto-PDT" nanoplatforms, which do not require the presence of an external light source to drive the PDT process. Instead, these platforms are driven either through oxidative chemical excitation in the form of chemiluminescence or radiological excitation from beta-emitting isotopes in the form of Cherenkov luminescence. In both, electronic excitations are generated and then transferred to the photosensitizer (PS) via Resonance Energy Transfer (RET) or Cherenkov Radiation Energy Transfer (CRET). Self-driven PDT has many components, so in this review, using contemporary examples from literature, we will breakdown the important concepts, strategies, and rationale behind the design of these self-propagating PDT nanoplatforms and critically review the aspects which make them successful and different from conventional PDT. Particular focus is given to the mechanisms of excitation and the different methods of transfer of excited electronic energy to the photosensitizer as well as the resulting therapeutic effect. The papers reviewed herein will be critiqued for their apparent therapeutic efficiency, and a basic rationale will be developed for what qualities are necessary to constitute an "effective" auto-PDT platform. This review will take a biomaterial engineering approach to the review of the auto-PDT platforms and the intended audience includes researchers in the field looking for a new perspective on PDT nanoplatforms as well as other material scientists and engineers looking to understand the mechanisms and relations between different parts of the complex "auto-PDT" system.

Metastatic Basal Cell Carcinoma of the Skin: A Comprehensive Literature Review, Including Advances in Molecular Therapeutics

Basal cell carcinoma (BCC) of the skin is the most common type of malignant human tumor. In Europe, the incidence of BCC ranges from 44.6 to 128 cases per 100,000 inhabitants annually, whereas in the United States, the yearly incidence rate ranges between 500 and 1500. The global incidence has been calculated to be as high as 10 million cases of BCC per year. There are 2 main clinical patterns of BCC-the familial BCC in basal cell nevus syndrome and sporadic BCC. The etiology of cutaneous BCC is usually the result of the interaction between solar ultraviolet radiation and genetic factors. Somatic or germline mutations in the effector components of the hedgehog signaling pathway (ie, PTCH1, PTCH2, SMO or SUFU genes) are responsible for ∼90% of the cases of both sporadic and familial BCC, all causing a constitutive activation of the hedgehog pathway. Cutaneous BCC very rarely metastasizes, and diagnosis in metastatic sites can be very difficult. Metastatic BCC has weakly effective therapeutic options with a poor prognosis until few years ago. In 2012, small-molecule therapies, involving inactivation of the hedgehog signaling pathway, and capable of reducing tumor growth and progression have been introduced into clinical practice for advanced (locally advanced or metastatic) BCC. We performed a comprehensive literature review on metastatic BCC and found at least 915 cases reported to date. In addition, we extensively discussed the differential diagnosis of metastatic BCC, and outlined the advances in clinical therapeutics involving these small molecules.

Targeting the Hedgehog Pathway in Cancer: Current Evidence and Future Perspectives

The Hedgehog pathway (HhP) plays an important role in normal embryonic development and its abnormal function has been linked to a variety of neoplasms. Recently, the complex mechanisms involved in this pathway have been deciphered and the cross talks with other important pathways involved in carcinogenesis have been characterized. This knowledge has led to the development of targeted therapies against key components of HhP, which culminated in the approval of vismodegib for the treatment of advanced basal cell carcinoma in 2012. Since then, other compounds have been developed and evaluated in preclinical and clinical studies with interesting results. Today, several medications against components of the HhP have demonstrated clinical activity as monotherapies and in combination with cytotoxic treatment or other targeted therapies against mitogenic pathways that are linked to the HhP. This review aims to clarify the mechanism of the HhP and the complex crosstalk with others pathways involved in carcinogenesis and to discuss both the evidence associated with the growing number of medications and combined therapies addressing this pathway and future perspectives.

Invasive Basal Cell Carcinoma of the Skin Treated Successfully with Vismodegib: A Case Report

INTRODUCTION

Basal cell carcinoma (BCC) is the most common skin cancer. It is primarily a local disease, and it very rarely causes metastatic disease. Chemotherapeutic agents had limited success in management of metastatic disease until the introduction of vismodegib. In this case report, we describe the presentation of a metastatic BCC that was not amenable to surgical resection or local treatment options and was treated successfully with vismodegib.

CASE PRESENTATION

A 69-year-old white man was referred to our surgical clinic for evaluation of an erosive left shoulder lesion. Biopsy in the clinic showed BCC with evidence of metastases on positron emission tomography-computed tomography scan. Tumors had invaded multiple bony structures and multiple organs, making surgical resection not an option. The decision was made to treat the patient with vismodegib. At 1-year follow-up, the patient's left shoulder lesion had improved with no evidence of metabolically active distant metastasis.

DISCUSSION

Although BCC is the most common skin cancer, it is usually a local disease and treated with local measures. Metastatic BCC is extremely rare, and in cases when surgical resection or local radiation are not viable options, chemotherapeutic agents typically offer very limited improvement. Vismodegib is an oral selective sonic hedgehog pathway inhibitor that shows benefit in patients with locally advanced or metastatic disease.

Hedgehog Pathway Inhibitors and Their Utility in Basal Cell Carcinoma: A Comprehensive Review of Current Evidence

Basal cell carcinoma (BCC) is the most commonly diagnosed malignancy in humans, and as such it poses a significant healthcare burden. The majority of BCC cases are amenable to cure by surgical extirpation. However, until recently there have been no good treatment options for a significant minority of advanced BCC cases, including locally advanced BCC and metastatic BCC. The introduction of a novel class of drugs, the Hedgehog pathway inhibitors, into clinical practice has ushered in a new treatment algorithm for the treatment of difficult BCC cases. In this review we present the latest available evidence and discuss areas for further research in this rapidly evolving field.

New developments in the treatment of basal cell carcinoma: update on current and emerging treatment options with a focus on vismodegib

Basal cell carcinoma (BCC) is the most common form of skin cancer worldwide. Although most BCCs can be treated by relatively simple surgical or nonsurgical methods, some patients with BCC may eventually develop advanced disease which can either be locally destructive or even include metastatic spread. The present review summarizes the current literature on the treatment of both early and advanced BCC with a focus on the hedgehog inhibitor vismodegib which has become an integral part of the management of patients with advanced BCC since its regulatory approval in 2012.