Energy analysis of PDT using thermography during the treatment of basal cell carcinoma

The changes in tissue temperature of basal cell carcinoma lesions were investigated during photodynamic therapy in order to better understand the effects and mechanisms of PDT in tissue. In this study, the monitoring of 40 lesions of basal cell carcinoma was performed during photodynamic therapy. The lesion region becomes thermally evident throughout the procedure, and there is an improved contrast of the lesion edges after the end of the irradiation. The comparison between thermal and fluorescence images showed a correlation between the PpIX evidenced through widefield fluorescence and the temperature gradient of the thermal images after the procedure, indicating that thermography is a potential diagnostic tool to evaluate the selective response of PDT. A model was created to calculate the amount of light energy converted to heat, tissue damage, and other energy transfer processes involved in the PDT. Using this model, it was shown that most of the energy conversion was in photodynamic action (48.7% and 48.3%, in first and second session, respectively), followed by the energy ratio attributable to blood perfusion (37.2%). This is evidence that photodynamic therapy does not generate a significant thermal component, an important aspect of the study of its mechanisms.

Clonal replacement of tumor-specific T cells following PD-1 blockade

Immunotherapies that block inhibitory checkpoint receptors on T cells have transformed the clinical care of patients with cancer1. However, whether the T cell response to checkpoint blockade relies on reinvigoration of pre-existing tumor-infiltrating lymphocytes or on recruitment of novel T cells remains unclear2-4. Here we performed paired single-cell RNA and T cell receptor sequencing on 79,046 cells from site-matched tumors from patients with basal or squamous cell carcinoma before and after anti-PD-1 therapy. Tracking T cell receptor clones and transcriptional phenotypes revealed coupling of tumor recognition, clonal expansion and T cell dysfunction marked by clonal expansion of CD8+CD39+ T cells, which co-expressed markers of chronic T cell activation and exhaustion. However, the expansion of T cell clones did not derive from pre-existing tumor-infiltrating T lymphocytes; instead, the expanded clones consisted of novel clonotypes that had not previously been observed in the same tumor. Clonal replacement of T cells was preferentially observed in exhausted CD8+ T cells and evident in patients with basal or squamous cell carcinoma. These results demonstrate that pre-existing tumor-specific T cells may have limited reinvigoration capacity, and that the T cell response to checkpoint blockade derives from a distinct repertoire of T cell clones that may have just recently entered the tumor.

A Practical Guide for the Follow-Up of Patients with Advanced Basal Cell Carcinoma During Treatment with Hedgehog Pathway Inhibitors

The Hedgehog pathway inhibitors (HPIs), vismodegib and sonidegib, are increasingly employed in the treatment of patients with advanced basal cell carcinoma (BCC). The aim of this review is to create a synthesis of available information in the literature regarding the follow-up of patients with advanced BCC treated with HPIs and to provide the treating physician with a structured practical guide to standardize clinical practice. Several challenges during treatment are addressed: to optimally evaluate tumor responses, to differentiate between resistance (HPI rechallenge not possible) and recurrence (HPI rechallenge may be possible) in case of BCC regrowth, to readily assess for toxicity and tolerability issues, to provide patients with practical ways and behaviors to effectively cope with adverse events, and to improve patient adherence and quality of life. IMPLICATIONS FOR PRACTICE: This is a practical guide for clinical practice regarding the monitoring and follow-up of patients with advanced basal cell carcinoma (BCC) during treatment with the Hedgehog pathway inhibitors (HPIs) vismodegib and sonidegib. This review aims to bridge the gap in knowledge of assessing tumor response for BCC with both an externally visible component and an infiltrating component measurable with imaging. Furthermore, it addresses the follow-up for adverse events as a challenging multistep process involving practices aiming to readily assess new-onset symptoms of HPI toxicity, perform total-body skin examination, and improve patient adherence and quality of life.

Characterisation of resistance mechanisms developed by basal cell carcinoma cells in response to repeated cycles of Photodynamic Therapy

Photodynamic Therapy (PDT) with methyl-aminolevulinate acid (MAL-PDT) is being used for the treatment of Basal cell carcinoma (BCC), but recurrences have been reported. In this work, we have evaluated resistance mechanisms to MAL-PDT developed by three BCC cell lines (ASZ, BSZ and CSZ), derived from mice on a ptch+/- background and with or without p53 expression, subjected to 10 cycles of PDT (10thG). The resistant populations showed mesenchymal-like structure and diminished proliferative capacity and size compared to the parental (P) cells. The resistance was dependent on the production of the endogenous photosensitiser protoporphyrin IX in the CSZ cell line and on its cellular localisation in ASZ and BSZ cells. Moreover, resistant cells expressing the p53 gene presented lower proliferation rate and increased expression levels of N-cadherin and Gsk3β (a component of the Wnt/β-catenin pathway) than P cells. In contrast, 10thG cells lacking the p53 gene showed lower levels of expression of Gsk3β in the cytoplasm and of E-cadherin and β-catenin in the membrane. In addition, resistant cells presented higher tumorigenic ability in immunosuppressed mice. Altogether, these results shed light on resistance mechanisms of BCC to PDT and may help to improve the use of this therapeutic approach.

Common skin bacteria protect their host from oxidative stress through secreted antioxidant RoxP

Cutibacterium acnes is an abundant skin commensal with several proposed mutualistic functions. A protein with strong antioxidant activity was recently identified from the C. acnes secretome. This protein, termed RoxP, facilitated aerobic bacterial growth in vitro and ex vivo. As reducing events naturally occurred outside of the bacterial cell, it was further hypothesized that RoxP could also serve to modulate redox status of human skin. The biological function of RoxP was here assessed in vitro and in vivo, through oxidatively stressed cell cultures and through protein quantification from skin affected by oxidative disease (actinic keratosis and basal cell carcinoma), respectively. 16S rDNA amplicon deep sequencing and single locus sequence typing was used to correlate bacterial prevalence to cutaneous RoxP abundances. We show that RoxP positively influence the viability of monocytes and keratinocytes exposed to oxidative stress, and that a congruent concentration decline of RoxP can be observed in skin affected by oxidative disease. Basal cell carcinoma was moreover associated with microbial dysbiosis, characterized by reduced C. acnes prevalence. C. acnes's secretion of RoxP, an exogenous but naturally occurring antioxidant on human skin, is likely to positively influence the human host. Results furthermore attest to its prospective usability as a biopharmaceutical.

Development of posaconazole-based analogues as hedgehog signaling pathway inhibitors

Inhibition of the hedgehog (Hh) signaling pathway has been validated as a therapeutic strategy to treat basal cell carcinoma and holds potential for several other forms of human cancer. Itraconazole and posaconazole are clinically useful triazole anti-fungals that are being repurposed as anti-cancer agents based on their ability to inhibit the Hh pathway. We have previously demonstrated that removal of the triazole from itraconazole does not affect its ability to inhibit the Hh pathway while abolishing its primary side effect, potent inhibition of Cyp3A4. To develop structure-activity relationships for the related posaconazole scaffold, we synthesized and evaluated a series of des-triazole analogues designed through both ligand- and structure-based methods. These compounds demonstrated improved anti-Hh properties compared to posaconazole and enhanced stability without inhibiting Cyp3A4. In addition, we utilized a series of molecular dynamics and binding energy studies to probe specific interactions between the compounds and their proposed binding site on Smoothened. These studies strongly suggest that the tetrahydrofuran region of the scaffold projects out of the binding site and that π-π interactions between the compound and Smoothened play a key role in stabilizing the bound analogues.

Resistance to anti-PD-1-based immunotherapy in basal cell carcinoma: a case report and review of the literature

BACKGROUND

Immunotherapy with immune checkpoint inhibitors has radically changed the management of a broad spectrum of tumors. In contrast, only very limited information is available about the efficacy of these therapies in non-melanoma skin cancers, especially in basal cell carcinoma. The latter malignancy is often associated with both an impairment of the host immune response and a high mutation burden, suggesting that immune checkpoint inhibitor-based immunotherapy may be effective in the treatment of this tumor.

CASE PRESENTATION

A 78-year-old woman was diagnosed with a metastatic non-small-cell-lung-cancer. Following the lack of response to two lines of systemic chemotherapy, she was treated with the anti-PD-1 monoclonal antibody nivolumab, obtaining a prolonged stable disease. Under nivolumab treatment, the patient developed a basal cell carcinoma of the nose. The latter was surgically resected. Immunohistochemical staining of tumor tissue showed a PD-L1 expression < 1% and lack of human leukocyte antigen class I subunit (i.e. heavy and light chain) expression on tumor cells. In addition, a limited number of T cells (CD3+) was present in the tumor microenvironment, with a higher number of regulatory T cells (Foxp3+) and macrophages (Cd11b+) as compared to a low infiltration of activated cytotoxic T cells (CD8+/ Granzyme B+). Two months following the surgical removal of the tumor, while still on nivolumab treatment, the patient relapsed with a basal cell carcinoma in the same anatomic site of the previous surgical excision. The tumor displayed the same pathological characteristics.

CONCLUSION

Preclinical lines of evidence suggest a potential role of immune checkpoint inhibitors for basal cell carcinoma treatment. However, limited clinical data is available. In the patient we have described administration of the immune checkpoint inhibitor nivolumab for the treatment of a responsive non-small cell carcinoma was associated with the development and relapse of a basal cell carcinoma tumor. This association is likely to reflect the resistance of basal cell carcinoma cells to anti-PD-1 based immunotherapy because of a "cold" tumor microenvironment characterized by lack of human leukocyte antigen class I expression, low PD-L1 expression and high number of immune regulatory cells.

A systematic review on the use of cryotherapy versus other treatments for basal cell carcinoma

BACKGROUND

Cryotherapy is a commonly discussed method for treatment of basal cell carcinoma skin cancer. Some uncertainty remains about its efficacy relative to other modalities.

OBJECTIVE

To determine the efficacy and adverse events profile of cryotherapy for the treatment of basal cell carcinoma compared to other therapeutic options or non-intervention.

METHODS

We systematically searched PubMed, OVID, Cochrane Library, EMBASE, CINHAL, and CANCERLIT databases for the following terms: "cryotherapy", AND "basal cell carcinoma", OR "cryosurgery" OR "cryoablation" up to April 2018. Two independent reviewers screened the results and extracted the data. Study endpoints included basal cell carcinoma recurrence, cosmetic outcome, and healing time. Study quality was assessed using the Jadad scale.

RESULTS

Six clinical studies met our inclusion criteria. The efficacy and safety of cryotherapy alone or with curettage in the treatment of primary superficial and nodular basal cell carcinoma was comparable to photodynamic therapy and surgery, respectively. Cryotherapy was inferior to radiation in terms of recurrence rate. Most patients had better cosmetic outcomes with photodynamic therapy and surgery compared to cryotherapy alone, and cryotherapy with curettage.

CONCLUSION

Current available data suggests equivalent efficacy of cryotherapy alone compared to photodynamic therapy or surgery, but inferior to radiotherapy. More studies are necessary to draw definitive conclusions.

Methods for multivariate recurrent event data with measurement error and informative censoring

In multivariate recurrent event data regression, observation of recurrent events is usually terminated by other events that are associated with the recurrent event processes, resulting in informative censoring. Additionally, some covariates could be measured with errors. In some applications, an instrumental variable is observed in a subsample, namely a calibration sample, which can be applied for bias correction. In this article, we develop two non-parametric correction approaches to simultaneously correct for the informative censoring and measurement errors in the analysis of multivariate recurrent event data. A shared frailty model is adopted to characterize the informative censoring and dependence among different types of recurrent events. To adjust for measurement errors, a non-parametric correction method using the calibration sample only is proposed. In the second approach, the information from the whole cohort is incorporated by the generalized method of moments. The proposed methods do not require the Poisson-type assumption for the multivariate recurrent event process and the distributional assumption for the frailty. Moreover, we do not need to impose any distributional assumption on the underlying covariates and measurement error. Both methods perform well, but the second approach improves efficiency. The proposed methods are applied to the Nutritional Prevention of Cancer trial to assess the effect of selenium treatment on the recurrences of basal cell carcinoma and squamous cell carcinoma.

A computational study of hedgehog signalling involved in basal cell carcinoma reveals the potential and limitation of combination therapy

BACKGROUND

The smoothened (SMO) receptor is an essential component of the Sonic hedgehog (SHH) signalling, which is associated with the development of skin basal cell carcinoma (BCC). SMO inhibitors are indicated for BCC patients when surgical treatment or radiation therapy are not possible. Unfortunately, SMO inhibitors are not always well tolerated due to severe side effects, and their therapeutical success is limited by resistance mutations.

METHODS

We investigated how common are resistance-causing mutations in two genomic databases which are not linked to BCC or other cancers, namely 1000 Genomes and ExAC. To examine the potential for combination therapy or other treatments, we further performed knowledge-based simulations of SHH signalling, in the presence or absence of SMO and PI3K/Akt inhibitors.

RESULTS

The database analysis revealed that of 18 known mutations associated with Vismodegib-resistance, three were identified in the databases. Treatment of individuals carrying such mutations is thus liable to fail a priori. Analysis of the simulations suggested that a combined inhibition of SMO and the PI3K/Akt signalling pathway may provide an effective reduction in tumour proliferation. However, the inhibition dosage of SMO and PI3K/Akt depended on the activity of phosphodiesterases (PDEs). Under high PDEs activities, SMO became the most important control node of the network. By applying PDEs inhibition, the control potential of SMO decreased and PI3K appeared as a significant factor in controlling tumour proliferation.

CONCLUSIONS

Our systems biology approach employs knowledge-based computer simulations to help interpret the large amount of data available in public databases, and provides application-oriented solutions for improved cancer resistance treatments.

Vismodegib and the Hedgehog Pathway Inhibitors: A Historical Perspective to Current Clinical Application

Vismodegib (Erivedge, Genentech-Roche) is the first in class of Hedgehog pathway inhibitors approved for treatment of metastatic basal cell carcinoma (BCC), or locally advanced BCC that has recurred after surgery or is not amenable to surgery or radiation. Its path to discovery has been unique and traces its origin to corn lilies, sheep, Drosophila flies, and the Hedgehog signaling pathway. J Drugs Dermatol. 2018;17(5):506-508.

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.

Long-term efficacy and safety of sonidegib in patients with locally advanced and metastatic basal cell carcinoma: 30-month analysis of the randomized phase 2 BOLT study

BACKGROUND

Patients with locally advanced basal cell carcinoma (laBCC) or metastatic BCC (mBCC), two difficult-to-treat populations, have had limited treatment options. Sonidegib, a hedgehog pathway inhibitor (HPI), was approved in laBCC based on results from the BOLT trial.

OBJECTIVE

To evaluate long-term efficacy and safety of sonidegib in laBCC and mBCC in the BOLT 18- and 30-month analyses.

METHODS

BOLT (NCT01327053, ClinicalTrials.gov), a double-blind phase 2 study, enrolled patients from July 2011 until January 2013. Eligible HPI-treatment-naïve patients with laBCC not amenable to curative surgery/radiotherapy or mBCC were randomized 1 : 2 to sonidegib 200 mg (laBCC, n = 66; mBCC, n = 13) or 800 mg (laBCC, n = 128; mBCC, n = 23). Tumour response was assessed per central and investigator review.

RESULTS

With 30 months of follow-up, among patients treated with sonidegib 200 mg (approved dose), objective response rates were 56.1% (central) and 71.2% (investigator) in laBCC and 7.7% (central) and 23.1% (investigator) in mBCC. Tumour responses were durable as follows: median duration of response was 26.1 months (central) and 15.7 months (investigator) in laBCC and 24.0 months (central) and 18.1 months (investigator) in mBCC. Five patients with laBCC and three with mBCC in the 200-mg arm died. Median overall survival was not reached in either population; 2-year overall survival rates were 93.2% (laBCC) and 69.3% (mBCC). In laBCC, efficacy was similar regardless of aggressive or non-aggressive histology. Sonidegib 200 mg continued to have a better safety profile than 800 mg, with lower rates of grade 3/4 adverse events (43.0% vs. 64.0%) and adverse events leading to discontinuation (30.4% vs. 40.0%).

CONCLUSION

Sonidegib continued to demonstrate long-term efficacy and safety in these populations. These data support the use of sonidegib 200 mg per local treatment guidelines.

A case illustrating successful eradication of recurrent, aggressive basal cell carcinoma located in a scar with vismodegib

Vismodegib is a small molecule inhibitor of the Hedgehog signaling pathway that has shown efficacy in the control of locally advanced or metastatic basal cell carcinoma, although proof of its effectiveness in the elimination of aggressive tumors is lacking. We report a case and provide complete histological evidence of a 69-year-old gentleman who presented with a recurrent, infiltrative, and sclerosing (morpheiform) basal cell carcinoma on his left upper lip that was entirely eradicated with a three-month course of vismodegib 150 mg daily. Complete histologic clearance of a tumor in a recurrent, infiltrative, and sclerosing basal cell carcinoma with vismodegib is uncommon.

Tumor Architecture and Notch Signaling Modulate Drug Response in Basal Cell Carcinoma

Hedgehog (Hh) pathway inhibitors such as vismodegib are highly effective for treating basal cell carcinoma (BCC); however, residual tumor cells frequently persist and regenerate the primary tumor upon drug discontinuation. Here, we show that BCCs are organized into two molecularly and functionally distinct compartments. Whereas interior Hh⁺/Notch⁺ suprabasal cells undergo apoptosis in response to vismodegib, peripheral Hh⁺⁺⁺/Notch^- basal cells survive throughout treatment. Inhibiting Notch specifically promotes tumor persistence without causing drug resistance, while activating Notch is sufficient to regress already established lesions. Altogether, these findings suggest that the three-dimensional architecture of BCCs establishes a natural hierarchy of drug response in the tumor and that this hierarchy can be overcome, for better or worse, by modulating Notch.

Vismodegib Use in Clinical Practice: Analysis of a United States Medical Claims Database

BACKGROUND

Information is limited on the use of vismodegib for treatment of advanced basal cell carcinoma beyond the setting of clinical trials.

OBJECTIVE

To investigate the treatment patterns and characteristics of patients treated with vismodegib in clinical practice.

METHODS

A longitudinal, retrospective cohort study was undertaken using data from a US commercial insurance claims (Truven Health Analytics MarketScan) database. Eligible patients were ≥18 years of age, with ≥1 claim for vismodegib from January 2012 to December 2015.

RESULTS

A total of 321 patients were included in the analysis. Approximately 20% of the patients took 1 or more treatment breaks of ≥ 30 days each before treatment discontinuation. Median duration of vismodegib treatment before the first treatment break and discontinuation was 4.0 and 5.5 months, respectively. Older age ( > 65 years) and absence of Gorlin syndrome were associated with increased risk for treatment interruption or discontinuation. Overall, 47% and 36% of patients underwent surgery or radiotherapy within the 6 months before and after vismodegib initiation, respectively.

CONCLUSIONS

Real-world evidence indicates that vismodegib is being used in clinical practice as part of combination treatment strategies. J Drugs Dermatol. 2018;17(2):143-148.

Pemphigus vulgaris induced by 5-aminolaevulinic acid-based photodynamic therapy

Pemphigus vulgaris (PV) is an autoimmune disorder resulting from the interaction between autoantibodies and desmoglein. Here, we report a case of PV developed after 5-aminolaevulinic acid-based photodynamic therapy (ALA-PDT). The harmful and deleterious effects of UV radiation on the onset, during course, and perpetuation of PV have been observed for decades. Correlation between reactive oxygen species (ROS) and PV have also been reported. Oxidative proteins, which are modified by ROS, and subsequent production of antibodies by immune system seem to be responsible for PV developed following ALA-PDT. We emphasize that ALA-PDT should be added to the list of possible factors triggering PV and this condition should be considered if blistering arises following ALA-PDT.