Development of squamous cell carcinoma into basal cell carcinoma under treatment with Vismodegib

Exploring vismodegib: A non-surgical breakthrough in the management of advanced periocular basal cell carcinoma

The management of periocular basal cell carcinoma (BCC) is challenging due to its proximity to the eyeball. Vismodegib, a Hedgehog pathway inhibitor, has emerged as a therapeutic option for locally advanced and metastatic BCC. To critically appraise the relevant evidence, we conducted a systematic review of observational and experimental studies assessing the efficacy and safety of vismodegib for periocular BCC. Thirty-seven trials, including 435 patients, were eligible. No randomized trials were retrieved. Complete and overall clinical response rates were 20-88 % and 68-100 %, respectively. Disease progression was observed at a maximum rate of 14 %. Recurrence rates varied between 0 % and 31 %. The most common side effects were muscle cramps, dysgeusia, weight loss and alopecia. Treatment with vismodegib improved health-related quality of life. In conclusion, vismodegib represents an important novel treatment for advanced periocular BCC, with good response rates and acceptable tolerability profile. Nevertheless, its full potential needs clarification through randomized controlled trials.

LY6D marks pre-existing resistant basosquamous tumor subpopulations

Improved response to canonical therapies requires a mechanistic understanding of dynamic tumor heterogeneity by identifying discrete cellular populations with enhanced cellular plasticity. We have previously demonstrated distinct resistance mechanisms in skin basal cell carcinomas, but a comprehensive understanding of the cellular states and markers associated with these populations remains poorly understood. Here we identify a pre-existing resistant cellular population in naive basal cell carcinoma tumors marked by the surface marker LY6D. LY6D+ tumor cells are spatially localized and possess basal cell carcinoma and squamous cell carcinoma-like features. Using computational tools, organoids, and spatial tools, we show that LY6D+ basosquamous cells represent a persister population lying on a central node along the skin lineage-associated spectrum of epithelial states with local environmental and applied therapies determining the kinetics of accumulation. Surprisingly, LY6D+ basosquamous populations exist in many epithelial tumors, such as pancreatic adenocarcinomas, which have poor outcomes. Overall, our results identify the resistant LY6D+ basosquamous population as an important clinical target and suggest strategies for future therapeutic approaches to target them.

c-FOS drives reversible basal to squamous cell carcinoma transition

While squamous transdifferentiation within subpopulations of adenocarcinomas represents an important drug resistance problem, its underlying mechanism remains poorly understood. Here, using surface markers of resistant basal cell carcinomas (BCCs) and patient single-cell and bulk transcriptomic data, we uncover the dynamic roadmap of basal to squamous cell carcinoma transition (BST). Experimentally induced BST identifies activator protein 1 (AP-1) family members in regulating tumor plasticity, and we show that c-FOS plays a central role in BST by regulating the accessibility of distinct AP-1 regulatory elements. Remarkably, despite prominent changes in cell morphology and BST marker expression, we show using inducible model systems that c-FOS-mediated BST demonstrates reversibility. Blocking EGFR pathway activation after c-FOS induction partially reverts BST in vitro and prevents BST features in both mouse models and human tumors. Thus, by identifying the molecular basis of BST, our work reveals a therapeutic opportunity targeting plasticity as a mechanism of tumor resistance.

Neoadjuvant vismodegib in the management of locally advanced periocular basal cell carcinoma

BACKGROUND/OBJECTIVES

Vismodegib, a hedgehog pathway inhibitor, has been used in the management of locally advanced basal cell carcinoma (BCC) not suitable for surgery or radiation therapy. We report our experience using neoadjuvant vismodegib for locally advanced periocular BCC, followed by surgical excision. Our aim was to assess the effect on the extent of surgical excision and histological response.

SUBJECTS/METHODS

A retrospective case series of patients treated with neoadjuvant vismodegib, for the management of locally advanced periocular BCC prior to surgical excision, with intraoperative margin control. Patients were treated until a maximum clinical response was seen. The difference between the estimated surgical margins prior to vismodegib and the eventual margins used was compared. Fine (1 mm) vertical sections through the excised tumour were performed to assess the histological response and look for a multifocal tumour.

RESULTS

Eight Caucasian patients had neoadjuvant treatment with vismodegib for a median duration of 6 months. Some clinical response was seen in all cases but was only partial in 6/8 patients. Histological evaluation of the excised specimen showed residual BCC in 6/8 cases and thus 2/8 showed complete histological regression. Two cases showed squamous differentiation. Side effects occurred in 7/8 patients all which resolved on cessation of therapy. The mean follow-up was 13.4 ± 5.2 months.

CONCLUSIONS

Neoadjuvant treatment of periocular BCC showed a mixed clinical and histological response. Final surgical excision achieved clear margins in all patients with no recurrence at 13 months and a reduction in predicted defect size, but possible squamous differentiation in two cases.

Cutaneous Squamous Cell Carcinoma: From Biology to Therapy

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and its incidence continues to rise. Although CSCC usually display a benign clinical behavior, it can be both locally invasive and metastatic. The signaling pathways involved in CSCC development have given rise to targetable molecules in recent decades. In addition, the high mutational burden and increased risk of CSCC in patients under immunosuppression were part of the rationale for developing the immunotherapy for CSCC that has changed the therapeutic landscape. This review focuses on the molecular basis of CSCC and the current biology-based approaches of targeted therapies and immune checkpoint inhibitors. Another purpose of this review is to explore the landscape of drugs that may induce or contribute to the development of CSCC. Beginning with the pathogenetic basis of these drug-induced CSCCs, we move on to consider potential therapeutic opportunities for overcoming this adverse effect.

Targeting cancer stem cells in drug discovery: Current state and future perspectives

In recent decades, cancer stem cells (CSCs) have been increasingly identified in many malignancies. CSC-related signaling pathways and their functions provide new strategies for treating cancer. The aberrant activation of related signaling pathways (e.g., Wnt, Notch, and Hedgehog pathways) has been linked to multiple types of malignant tumors, which makes these pathways attractive targets for cancer therapy. CSCs display many characteristic features, such as self-renewal, differentiation, high tumorigenicity, and drug resistance. Therefore, there is an urgent need to develop new therapeutic strategies to target these pathways to control stem cell replication, survival, and differentiation. Notable crosstalk occurs among different signaling pathways and potentially leads to compensatory escape. Therefore, multitarget inhibitors will be one of the main methods to overcome the drug resistance of CSCs. Many small molecule inhibitors of components of signaling pathways in CSCs have entered clinical trials, and some inhibitors, such as vismodegib, sonidegib, and glasdegib, have been approved. Tumor cells are susceptible to sonidegib and vismodegib resistance due to mutations in the Smo protein. The signal transducers and activators of transcription 3 (STAT3) inhibitor BBI608 is being evaluated in a phase III trial for a variety of cancers. Structural derivatives of BBI608 are the main focus of STAT3 inhibitor development, which is another strategy for CSC therapy. In addition to the potential pharmacological inhibitors targeting CSC-related signaling pathways, other methods of targeting CSCs are available, such as nano-drug delivery systems, mitochondrion targeting, autophagy, hyperthermia, immunotherapy, and CSC microenvironment targeting. In addition, we summarize the latest advances in the clinical development of agents targeting CSC-related signaling pathways and other methods of targeting CSCs.

Genetic Mutations Underlying Phenotypic Plasticity in Basosquamous Carcinoma

Basosquamous carcinoma (BSC) is an aggressive skin neoplasm with the features of both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). While genetic drivers of BCC and SCC development have been extensively characterized, BSC has not been well studied, and it remains unclear whether these tumors originally derive from BCC or SCC. In addition, it is unknown which molecular pathways mediate the reprogramming of tumor keratinocytes toward basaloid or squamatized phenotypes. We sought to characterize the genomic alterations underlying sporadic BSC to elucidate the derivation of these mixed tumors. We identifed frequent Hedgehog (Hh) pathway mutations in BSCs, implicating Hh deregulation as the primary driving event in BSC. Principal component analysis of BCC and SCC driver genes further demonstrate the genetic similarity between BCC and BSC. In addition, 45% of the BSCs harbor recurrent mutations in the SWI/SNF complex gene, ARID1A, and evolutionary analysis revealed that ARID1A mutations occur after PTCH1 but before SCC driver mutations, indicating that ARID1A mutations may bestow plasticity enabling squamatization. Finally, we demonstrate mitogen-activated protein kinase pathway activation and the loss of Hh signaling associated with the squamatization of BSCs. Overall, these results support the genetic derivation of BSCs from BCCs and highlight potential factors involved in modulating tumor reprogramming between basaloid and squamatized phenotypes.

Vismodegib: A Review in Advanced Basal Cell Carcinoma

Vismodegib (Erivedge^®) is the first-in-class, oral small molecule inhibitor of the Hedgehog (Hh) pathway, abnormal activation of which is associated with basal cell carcinoma (BCC). In the USA, vismodegib is indicated for the treatment of adults with metastatic BCC (mBCC) or with locally-advanced BCC (LaBCC) that has recurred following surgery or who are not candidates for surgery, and who are not candidates for radiation. Similarly, in the EU, vismodegib is indicated for the treatment of adult patients with symptomatic mBCC, or with laBCC inappropriate for surgery or radiotherapy. The full European approval of vismodegib was based on the results of two phase II, open-label, noncomparative, international trials (ERIVANCE BCC and STEVIE), both of which showed high rates of tumour control in the indicated patient populations, including individuals with or without Gorlin syndrome. These studies also showed that vismodegib has an acceptable and manageable tolerability profile characterized by a number of class-related treatment-emergent adverse events, including muscle spasms, taste disturbances, alopecia, weight loss and asthenia (fatigue). Primary and secondary resistance to vismodegib has been documented, albeit at a low rate compared with some other targeted therapies. Vismodegib is therefore an effective and generally well tolerated systemic therapy for patients with mBCC and laBCC that can no longer be suitably controlled with surgery and/or radiotherapy. Historically, it is the first member of a class of drugs (Hh pathway inhibitors) that are now considered to be first-line treatment options for such individuals.

Loss of Primary Cilia Drives Switching from Hedgehog to Ras/MAPK Pathway in Resistant Basal Cell Carcinoma

Basal cell carcinomas (BCCs) rely on Hedgehog (HH) pathway growth signal amplification by the microtubule-based organelle, the primary cilium. Despite naive tumor responsiveness to Smoothened inhibitors (Smoⁱ), resistance in advanced tumors remains common. Although the resistant BCCs usually maintain HH pathway activation, squamous cell carcinomas with Ras/MAPK pathway activation also arise, and the molecular basis of tumor type and pathway selection are still obscure. Here, we identify the primary cilium as a critical determinant controlling tumor pathway switching. Strikingly, Smoothened inhibitor-resistant BCCs have an increased mutational load in ciliome genes, resulting in reduced primary cilia and HH pathway activation compared with naive or Gorlin syndrome patient BCCs. Gene set enrichment analysis of resistant BCCs with a low HH pathway signature showed increased Ras/MAPK pathway activation. Tissue analysis confirmed an inverse relationship between primary cilia presence and Ras/MAPK activation, and primary cilia removal in BCCs potentiated Ras/MAPK pathway activation. Moreover, activating Ras in HH-responsive cell lines conferred resistance to both canonical (vismodegib) and noncanonical (atypical protein kinase C and MRTF inhibitors) HH pathway inhibitors and conferred sensitivity to MAPK inhibitors. Our results provide insights into BCC treatment and identify the primary cilium as an important lineage gatekeeper, preventing HH-to-Ras/MAPK pathway switching.

Use of vismodegib for the treatment of multiple basal cell carcinomas in a patient with xeroderma pigmentosum

A female patient with xeroderma pigmentosum and multiple basal cell carcinomas was treated with a hedgehog pathway inhibitor (vismodegib), which successfully treated the majority of her basal cell carcinomas while preventing the appearance of new lesions. The sum diameter of lesions showed a 61% decrease after 16.5 months of treatment, although after 18.5 months of treatment, a persistent lesion showed progression and metatypical characteristics; adverse events included persistent alopecia muscle cramps, dysgeusia, and amenorrhea. Despite these limitations, vismodegib may have a role in the treatment of some patients with xeroderma pigmentosum.

Ocular preservation with neoadjuvant vismodegib in patients with locally advanced periocular basal cell carcinoma

Background/Aims

Locally advanced (T4 per American Joint Committee on Cancer (AJCC) 8th edition) periocular basal cell carcinoma (BCC) can lead to loss of the eye. We report the neoadjuvant use of vismodegib followed by surgery in patients with such lesions with eye preservation as primary goal.

Methods

This retrospective interventional study includes all patients with a T4 periocular BCC (per 8th edition AJCC for eyelid carcinoma) treated by the senior author between 2013 and 2017 with neoadjuvant vismodegib prior to definitive surgery.

Results

Eight patients had a T4 tumour. Six patients presented with recurrent disease. Indications for neoadjuvant treatment were an unresectable tumour in one patient, an attempt to avoid an orbital exenteration in six patients and an attempt to avoid disfiguring facial surgery in one patient. Patients were treated for a median of 14 months (range: 4–36 months). All patients underwent an eye-sparing surgery following neoadjuvant vismodegib and all final surgical margins were negative for tumour. Five patients had a complete response to vismodegib with no microscopic residual BCC found during surgery; three patients had a significant partial response with residual tumour found on pathology. At last follow-up, a mean of 18 (range: 6–43) months after surgery, all patients were off-vismodegib and alive without evidence of disease.

Conclusions

Neoadjuvant vismodegib for locally advanced (T4) periocular BCC enabled an eye-sparing surgery in all patients in our cohort. Prolonged treatment was well tolerated by most patients. Over half of patients achieved a complete response with no residual microscopic disease. Careful long-term follow-up is needed to confirm long-term disease-free survival.

Small Molecule Inhibitors of the Hedgehog Pathway in the Treatment of Basal Cell Carcinoma of the Skin

Basal cell carcinoma (BCC) is the most common type of skin cancer, with rising incidence rates primarily attributed to an aging population and ultraviolet radiation exposure. While the majority of BCCs are localized and respond to standard therapies, a very small minority of these tumors become locally destructive or metastasize. These advanced BCCs may not be amenable to localized treatment with surgery and/or radiation therapy. Most BCCs result from mutations in key receptors in the Hedgehog (HH) signaling pathway. As a result, identification of drugs that inhibit the receptor Smoothened (SMO) in the HH pathway has resulted in novel therapeutic approaches to treating patients with advanced BCC. These HH-pathway inhibiting medications have shown efficacy in clinical trials, and two medications, vismodegib and sonidegib, have received FDA approval. However, several limitations of these drugs have been identified, including treatment-limiting adverse events, drug resistance, and the formation of additional malignancies. This paper aims to summarize the clinical trials leading to the approval of SMO inhibitors, as well as reviewing potential mechanisms driving tumor resistance and the formation of cutaneous squamous cell carcinomas. Strategies to overcome some of these challenges, including the development of drugs that inhibit other downstream targets in the HH pathway, are the subject of ongoing clinical trials.

Chimeric Monoclonal Antibody Cetuximab Targeting Epidermal Growth Factor-Receptor in Advanced Non-Melanoma Skin Cancer

BACKGROUND:

Non-melanoma skin cancer (NMSC) is the most common malignancy in humans. Targeted therapy with monoclonal antibody cetuximab is an option in case of advanced tumor or metastasis.

AIM:

We present and update of the use of cetuximab in NMSC searching PUBMED 2011-2017.

METHODS:

The monoclonal antibody cetuximab against epidermal growth factor receptor (EGFR) has been investigated for its use in NMSC during the years 2011 to 2017 by a PUBMED research using the following items: “Non-melanoma skin cancer AND cetuximab,” “cutaneous squamous cell carcinoma AND cetuximab,” and “basal cell carcinoma AND cetuximab”, and “cetuximab AND skin toxicity”. Available data were analyzed including case reports.

RESULTS:

Current evidence of cetuximab efficacy in NMSC was mainly obtained in cutaneous SCC and to a lesser extend in BCC. Response rates vary for neoadjuvant, adjuvant, mono- and combined therapy with cetuximab. Management of cutaneous toxicities is necessary. Guidelines are available.

CONCLUSIONS:

Cetuximab is an option for recurrent or advanced NMSC of the skin. It seems to be justified particularly in very high-risk tumors. There is a need for phase III trials.

Carcinogenicity assessment of the Hedgehog pathway inhibitor, vismodegib in Tg.rasH2 mice and Sprague-Dawley rats

Vismodegib (also known as GDC-0449) is a novel small molecule inhibitor of the Hedgehog (Hh) signaling pathway currently approved for the treatment of metastatic or locally advanced basal cell carcinoma (BCC) in humans. Its tumorigenic potential was assessed in dedicated carcinogenicity studies in rasH2 transgenic (Tg.rasH2) mice and Sprague Dawley (SD) rats. Tumorigenicity potential of vismodegib was identified in rats only and was limited to benign hair follicle tumors, including pilomatricomas and keratoacanthomas at exposures of ≥0.1-fold and ≥0.6-fold, respectively, of the steady-state exposure (AUC_0-24h) of the recommended human dose. No malignant tumors were identified in either species. Overall, the totality of pharmacology and nonclinical safety data (lack of genotoxicity, in vitro secondary pharmacological binding, and immunoregulatory effects, and limited effects on the endocrine system) suggests that the development of the benign hair follicle tumors may be related to pharmacologically-mediated disruption of hair follicle morphogenesis, although the exact mechanism of tumorigenesis is unclear. Hair follicle tumors have not been reported in vismodegib-treated patients. The relevance of this finding in rats to patients is uncertain.

Long-Term Follow-Up Results of Topical Imiquimod Treatment in Basal Cell Carcinoma

BACKGROUND

Imiquimod 5% topical cream is approved for treatment of superficial basal cell carcinoma (BCC). Data on the long-term efficacy and usage in other BCC subtypes are scarce.

OBJECTIVE

Evaluation of long-term safety and efficacy of topical imiquimod treatment in various BCC subtypes and locations, with individualized treatment duration.

MATERIALS AND METHODS

Histopathologically confirmed BCCs treated solely with topical imiquimod were identified retrospectively and included in this study. Clinical and histopathologic tumor clearances were the primary end point. After treatment was concluded, patients were examined every 3 to 6 months.

RESULTS

In total, 24 BCC samples from 22 patients (F:M = 9:13; mean age: 73.5 years, SD: 10.767) were evaluated. The majority of the lesions were located in the head and neck area (83%). Mean treatment duration until complete clearance was 15.7 ± 6.9 weeks (6-28 weeks). Imiquimod was discontinued in 3 lesions, due to either clinically or histopathologically insufficient response. During follow-up, 2 lesions recurred, at 42 and 50 months after treatment. During a mean follow-up time of 72.7 (SD = 9) months, 79.1% of the lesions were cured without local recurrence.

CONCLUSION

Although imiquimod is only approved for superficial BCC, treatment success was high among the study patients with various histological subtypes, with good long-term cosmetic results.

Inoperable infiltrative basal cell carcinoma successfully treated with vismodegib

Basal cell carcinoma (BCC) is the most common skin cancer but usually has a good prognosis. However, there is a subset of BCC cases with a less favorable prognosis. For patients with locally advanced, recurrent or metastatic BCCs who are not suitable for surgery or radiotherapy, small-molecule drug inhibitors of hedgehog pathway are a new therapeutic opportunity. Here, we present a case of infiltrative BCC with multiple recurrences. Wide excision with reconstructive plastic surgery was performed initially with adjuvant radiotherapy. Due to multiple recurrences afterward, radiotherapy, topical imiquimod and oral itraconazole were used but were not effective. Finally, the patient was treated with vismodegib which led to a complete response. Moreover, the patient's symptoms due to the locally diffused cancer resolved.

Basosquamous Carcinoma: Controversy, Advances, and Future Directions

BACKGROUND

Basosquamous carcinoma is a rare cutaneous neoplasm that has caused considerable controversy as to its classification, pathogenesis, and management.

OBJECTIVE

To review and summarize current literature on the definition, pathogenesis, incidence, and management of basosquamous carcinoma.

MATERIALS AND METHODS

Through December 2015, an electronic search of the Pubmed database was performed using combinations of basosquamous carcinoma and metatypical basal cell carcinoma as search terms.

RESULTS

A selection of 39 publications including case reports and series, retrospective studies, and systematic reviews of the literature were included. Descriptions of the definition of basosquamous carcinoma, clinical behavior, histopathological characteristics, current treatment therapies, and future advances are summarized.

CONCLUSION

This systematic review provides a comprehensive overview of the current understanding of basosquamous carcinoma. Further study is required to elucidate the mechanisms driving the formation of this aggressive tumor.

Role of Vismodegib in the Management of Advanced Periocular Basal Cell Carcinoma

BACKGROUND

Vismodegib is the first selective hedgehog pathway inhibitor approved to treat locally advanced and metastatic basal cell carcinoma (BCC). Limited information is available concerning its role in managing advanced BCC around the eye.

METHODS

The medical literature was searched for cases of nonsyndromic periocular BCC treated with vismodegib. Clinical information was abstracted and analyzed. In addition, a review of the pharmacology of vismodegib, including general effectiveness and safety, was conducted.

RESULTS

Thirty study patients with nonsyndromic periocular BCC treated with vismodegib were found in the literature. Vismodegib was used in 3 ways: medical therapy, adjuvant therapy prior to surgery or radiotherapy, and treatment of positive surgical margins. Complete regression was reported in 9 study patients (30%), with follow-up visits after therapy averaging fewer than 5 months. Four study participants developed squamous cell carcinoma while receiving treatment.

CONCLUSIONS

Too few cases exist to draw any conclusions on the role that vismodegib might play in the management of periocular BCC. In addition, long-term follow-up data are not yet available. Although the objective response rate of advanced BCC is impressive in study patients receiving vismodegib, well-controlled clinical studies are needed to determine whether vismodegib has any impact on survival or quality of life.

Advanced basal cell carcinoma, the hedgehog pathway, and treatment options - role of smoothened inhibitors

Cutaneous basal cell carcinoma (BCC) is the most common human cancer and its incidence is rising worldwide. Ultraviolet radiation exposure, including tanning bed use, as well as host factors play a role in its development. The majority of cases are treated and cured with local therapies including surgery. Yet, the health care costs of diagnosis and treatment of BCCs in the US is substantial. In the United States, the cost of nonmelanoma skin cancer care in the Medicare population is estimated to be US$426 million per year. While rare, locally advanced BCCs that can no longer be controlled with surgery and/or radiation, and metastatic BCCs do occur and can be associated with significant morbidity and mortality. Vismodegib (GDC-0449), a smoothened inhibitor targeted at the hedgehog pathway, is the first US Food and Drug Association (FDA)-approved agent in the treatment of locally advanced, unresectable, and metastatic BCCs. This class of agents appears to be changing the survival rates in advanced BCC patients, but appropriate patient selection and monitoring are important. Multidisciplinary assessments are essential for the optimal care and management of these patients. For some patients with locally advanced BCC, treatment with a hedgehog inhibitor may eliminate the need for an excessively disfiguring or morbid surgery.

RAS/MAPK Activation Drives Resistance to Smo Inhibition, Metastasis, and Tumor Evolution in Shh Pathway-Dependent Tumors

Aberrant Shh signaling promotes tumor growth in diverse cancers. The importance of Shh signaling is particularly evident in medulloblastoma and basal cell carcinoma (BCC), where inhibitors targeting the Shh pathway component Smoothened (Smo) show great therapeutic promise. However, the emergence of drug resistance limits long-term efficacy, and the mechanisms of resistance remain poorly understood. Using new medulloblastoma models, we identify two distinct paradigms of resistance to Smo inhibition. Sufu mutations lead to maintenance of the Shh pathway in the presence of Smo inhibitors. Alternatively activation of the RAS-MAPK pathway circumvents Shh pathway dependency, drives tumor growth, and enhances metastatic behavior. Strikingly, in BCC patients treated with Smo inhibitor, squamous cell cancers with RAS/MAPK activation emerged from the antecedent BCC tumors. Together, these findings reveal a critical role of the RAS-MAPK pathway in drug resistance and tumor evolution of Shh pathway-dependent tumors.