Delivery of Targeted Co(III)-DNA Inhibitors of Gli Proteins to Disrupt Hedgehog Signaling

The Hedgehog (Hh) signaling pathway is integral for embryonic development and normal cell maintenance. However, aberrant expression of the Hh pathway is recognized as the oncogenic driving force for basal cell carcinoma (BCC). Current chemotherapeutic treatments that inhibit Hh signaling allow treatment of only locally advanced and metastatic BCCs via inhibition of the transmembrane protein, smoothened. It is further recognized that downstream mutations often lead to chemoresistant tumor recurrence. The Gli proteins are the ultimate regulators of Hh signaling and belong to a family of Cys2His2 zinc finger transcription factors (ZnFTFs) that we have shown can be irreversibly inhibited by a series of cobalt(III) Schiff base-DNA (CoSB-DNA) conjugates. However, a significant challenge is the delivery of CoSB-DNA complexes in mammalian tissues. Herein, we report a polyethyleneimine-functionalized graphene oxide nanoconjugate (GOPEI) that delivers CoGli, a CoSB-DNA complex that targets Gli specifically. We describe the characterization of the surface functionalization of GOPEI and accumulation in ASZ murine BCC cells via confocal microscopy and inductively coupled plasma-mass spectrometry (ICP-MS). Lysosomal escape of CoGli is further confirmed by confocal microscopy. We report the successful targeting of Gli by CoGli and a 17-fold improvement in potency over small-molecule Gli inhibitor GANT-61 in inhibiting Hh-driven migration of ASZ murine BCC cells. This study provides a promising starting point for further investigating CoGli inhibitors of Hh signaling in developed mammalian tissues.

Metatypical basal cell carcinoma: from the primary tumour to a generalized metastatic process - description of diagnostics and combination therapy of an extremely rare skin cancer

INTRODUCTION

Basal cell carcinoma (BCC) is the most common form of skin cancer. The hallmarks of this carcinoma are the absence of distant metastases and local malignancy. Metatypical basal cell carcinoma (MTBBC) is rare variant that it is considered to be a more aggressive form, with a higher potential for metastases and recurrence. Probably due to its very rare occurrence, data on pathogenesis, course and treatment are inconsistent.

CASE REPORT

An unusual and very aggressive course of MTBBC with multiple metastases is prtesented. Repeated histopathological evaluation shows the diagnostic difficulties in this type of tumour. Therapeutic attempts, including targeted therapy with vismodegib, were unsuccessful.

CONCLUSIONS

This case showed that it should always be taken into account that each case of diagnosed BCC may turn out to be metatypical variant with a much more aggressive course and worse prognosis. For this reason, intensive follow-up after a completed treatment is recommended.

Real-world assessment and treatment of locally advanced basal cell carcinoma: Findings from the RegiSONIC disease registry

BACKGROUND

Limited information is available regarding real-world treatment patterns and their effectiveness and safety in patients with locally advanced basal cell carcinoma, including patients not typically represented in clinical trials. The purpose of the current study was to describe how clinicians diagnose and treat locally advanced basal cell carcinoma in the United States.

METHODS

This prospective, multicenter, observational registry study included patients with newly diagnosed, Hedgehog pathway inhibitor-naive locally advanced basal cell carcinoma without basal cell carcinoma nevus syndrome (n = 433) treated at 75 US academic and community practices, including dermatology, Mohs surgery, and medical oncology sites. The main outcomes of this study were treatment patterns and associated effectiveness and safety for patients with locally advanced basal cell carcinoma in real-world settings.

RESULTS

Determination of locally advanced basal cell carcinoma was mainly based on lesion size (79.6% of patients), histopathology (54.3%), extent of involvement (49.0%), and location (46.2%). Within 90 days of determination of locally advanced disease, 115 patients (26.6%) received vismodegib, 251 (58.0%) received surgery/other (non-vismodegib) treatment, and 67 (15.5%) had not yet received treatment (observation). Vismodegib-treated patients had a higher prevalence of high-risk clinical features predictive for locoregional recurrence than those with non-vismodegib treatment or observation. Clinical response rate was 85.1% with vismodegib and 94.9% with non-vismodegib treatment (primarily surgery). The most common adverse events with vismodegib were ageusia/dysgeusia, muscle spasms, alopecia, and weight loss. Rates of cutaneous squamous cell cancers were comparable between vismodegib and non-vismodegib treatment.

CONCLUSIONS

This prospective observational study offers insight on real-world practice, treatment selection, and outcomes for a nationally representative sample of US patients with locally advanced basal cell carcinoma. For patients with lesions that were not amenable to surgery, vismodegib treatment was associated with effectiveness and safety that was consistent with that observed in clinical trials.

The use of HCT and/or ACE inhibitors significantly increases the risk of non-melanotic skin cancer in the periocular region

Background/Aims

To investigate a possible association between the use of hydrochlorothiazide (HCT) and/or angiotensin-converting enzyme inhibitors (ACE inhibitors) and the occurrence of periocular non-melanoma skin cancer.

Methods

The files of 929 patients from the University Medical Center Hamburg-Eppendorf who were surgically treated for suspected periocular malignancy were evaluated retrospectively regarding the occurrence of non-melanoma skin cancer and concomitant medication. To be able to put the data in an overall context, we also analyzed age-matched routine data of the DAK-Gesundheit (DAK-G), a nationwide operating German health insurance company.

Results

Of the 929 patient records examined, who underwent surgical excision for suspected non-melanotic malignancy, non-melanocytic skin cancer could actually be determined by histology in 199 patients. In total, 176 patients (103 women, 72 men) had a basal cell carcinoma and 23 patients (16 women, 7 men) suffered from squamous cell carcinoma. The rate of intake of HCT or ACE inhibitors in our patient collective with non-melanotic skin cancer is significantly higher than in the general age-matched population (ORACE: 2.51, p < 0.001; ORHCT: 7.24, p < 0.001, ORBOTH: 4.61, p < 0.001).

Conclusion

The rate of intake of HCT or ACE inhibitors is significantly higher in our patient collective with non-melanotic skin cancer compared to the group from the age-matched general population (DAK insured (p < 0.001)) compared to the routine data of the DAK-G. This leads us to the conclusion that taking the medication is associated with an increased risk for non-melanotic skin cancer. We recommend regular skin cancer screening, moderate ordination of photosensitizing medication, but above all comprehensive clarification of possible risks.

Affinity-based protein profiling identifies vitamin D3 as a heat shock protein 70 antagonist that regulates hedgehog transduction in murine basal cell carcinoma

Vitamin D3 (VD3) is a seco-steroid that inhibits the Hedgehog (Hh) signaling pathway. Initial studies suggested its anti-Hh activity results from direct inhibition of Smoothened, a seven-transmembrane cell surface receptor that is a key regulator of the Hh signaling cascade. More recently, a role for the Vitamin D Receptor in mediating inhibition of Hh-signaling by seco-steroid has been suggested. Herein, an affinity-based protein profiling study was carried out to better understand the cellular proteins that govern VD3-mediated anti-Hh activity. We synthesized a novel biotinylated VD3 analogue (8) for use as a chemical probe to explore cellular binding targets of the seco-steroidal scaffold. Through a series of pull-down experiments and follow up mass spectrum analyses, heat shock protein 70 (Hsp70) was identified as a primary binding protein of VD3. Hsp70 was validated as a binding target of VD3 through a series of biochemical and cellular assays. VD3 bound with micromolar affinity to Hsp70. In addition, both selective knockdown of Hsp70 expression and pharmacological inhibition of its activity with known Hsp70 inhibitors suppressed Hh-signaling transduction in murine basal cell carcinoma cells, suggesting that Hsp70 regulates proper Hh-signaling. Additional cellular assays suggest that VD3 and its seco-steroidal metabolites inhibit Hh-signaling through different mechanisms.

[PROLONGED COMPLETE REMISSION AFTER A SHORT COURSE OF HEDGEHOG PATHWAY INHIBITORS IN PATIENTS WITH ADVANCED BASAL CELL CARCINOMA: AN ALTERNATIVE TO SURGERY?]

Basal cell carcinoma (BCC) is a cancer that arises from the basal layer of the epidermis and is most often caused by exposure to UV radiation. Most BCCs are localized and can be fully treated by surgical removal or topical treatment. In the last decade, it has been found that the hedgehog pathway, a signaling pathway that regulates embryonic development, has a pivotal role in the pathogenesis of BCC in adults. Therefore, two drugs that inhibit the hedgehog pathway have been developed. These drugs, indicated for metastatic or locally advanced BCC, may cause a rapid clinical and imaging response, but have an adverse reaction that includes muscle spasms, alopecia, dysgeusia and fatigue, and often leads to drug discontinuation. Due to the high rates of treatment discontinuation, the possibility of administering the drug intermittently was examined and, indeed, a decrease in adverse reactions together with tumor response was observed. Additionally, it seems that patients who discontinue treatment may benefit from long-term remission. These cases indicate the possibility of changing the schedule of administration of the drug. We hereby report two cases of patients who were treated with radiation therapy for ringworm in their childhood and developed BCC. The patients were treated with a hedgehog pathway inhibitor with complete tumor regression. After treatment was discontinued due to adverse reactions, no recurrence of the tumor was observed over a period of almost two years.

Phase II Open-Label, Single-Arm Trial to Investigate the Efficacy and Safety of Topical Remetinostat Gel in Patients with Basal Cell Carcinoma

PURPOSE

The mainstay of treatment for basal cell carcinoma (BCC) is surgical excision, which can result in significant associated morbidity, particularly for patients with recurrent tumors. We previously conducted a drug repositioning screen using molecular data from human BCCs and identified histone deacetylase (HDAC) inhibitors as a potential treatment for BCC. Here we conduct the first proof-of-principle study of a topical pan-HDAC inhibitor, remetinostat, in human BCC.

PATIENTS AND METHODS

We conducted a phase II, open-label, single-arm, single-institution trial of a topical HDAC inhibitor. Participants with at least one BCC were recruited. All participants applied 1% remetinostat gel three times daily for 6 weeks, with measurements of tumor diameter conducted at baseline and week 8. Surgical excision of the remaining tumor was conducted at the end of the study and microscopic evaluation was performed.

RESULTS

Thirty-three per-protocol tumors from 25 participants were included in the analysis. The overall response rate, defined as the proportion of tumors achieving more than 30% decrease in the longest diameter from baseline to week 8, was 69.7% [90% confidence interval (CI), 54%-82.5%]. On pathologic examination, 54.8% of tumors demonstrated complete resolution. Pharmacodynamic analysis demonstrated similar levels of acetylated histone H3 in skin tissue before and after treatment, however, phosphorylation was increased. No systemic adverse events were reported.

CONCLUSIONS

The HDAC inhibitor remetinostat is a well-tolerated and effective topical treatment for reducing BCC disease burden in a clinically significant manner. This provides in-human validation of HDAC inhibitors as a therapy for BCC.

18F-FDG PET/CT Monitoring of Response to Programmed Death Protein 1 Blockade in Metastatic Basal Cell Carcinoma

ABSTRACT

A 73-year-old woman with history of metastatic basal cell carcinoma presented with a large spinal mass demonstrating a high mutational burden of 111 mutations/Mb. She underwent T12 corpectomy and T10-L3 posterior spinal fusion followed by adjuvant radiation. After 2 years of surveillance, FDG PET/CT and a contrast-enhanced MRI revealed recurrence, prompting salvage therapy with the hedgehog signaling pathway inhibitor, sonidegib, which only transiently stabilized the disease. An off-label treatment with the programmed death protein 1 inhibitor, pembrolizumab, was initiated. Serial FDG PET/CT showed gradual decline in tumor metabolism over the next 12 months, leading to complete metabolic response.

A Review of Hedgehog Inhibitors Sonidegib and Vismodegib for Treatment of Advanced Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common malignancy in fair-skinned populations. Most cases are successfully treated with surgery, but in advanced BCC&mdash;including locally advanced BCC and metastatic BCC&mdash;surgery is likely to result in substantial morbidity or unlikely to be effective. In those patients, the systemic Hedgehog inhibitors (HHIs) sonidegib and vismodegib are the only approved pharmacologic treatment option. Although a number of clinical studies highlight the similarities and differences between the two HHIs, no head-to-head clinical comparison is available. Results from the pivotal BOLT and ERIVANCE clinical studies for sonidegib and vismodegib, respectively, demonstrate similar efficacy measured by objective response rate, complete response rate, and histologic tumor subtype. Safety results for both studies are comparable with similar common adverse events reported for muscle spasms, alopecia, and dysgeusia. A notable difference between sonidegib and vismodegib is their respective pharmacokinetic profiles with sonidegib reaching peak concentration in plasma within 2&ndash;4 hours of dosing and steady state in plasma achieved by week 17 of treatment, while vismodegib reaches peak plasma concentration approximately 2 days after a single dose and steady state within 21 days of repeated dosing. This review compares efficacy, safety, and pharmacokinetics of sonidegib and vismodegib based on published literature to date. J Drugs Dermatol. 2021;20(2):156-165. doi:10.36849/JDD.5657 THIS ARTICLE HAD BEEN MADE AVAILABLE FREE OF CHARGE. PLEASE SCROLL DOWN TO ACCESS THE FULL TEXT OF THIS ARTICLE WITHOUT LOGGING IN. NO PURCHASE NECESSARY. PLEASE CONTACT THE PUBLISHER WITH ANY QUESTIONS.

Intralesional 5-Fluorouracil for Treatment of Non-Melanoma Skin Cancer: A Systematic Review

BACKGROUND

Surgical excision is the paradigm treatment option for non-melanoma skin cancer (NMSC), however intralesional fluorouracil (IL 5-FU) is an efficacious alternative and superior to other chemotherapy agents in NMSC. Yet, little summative data exists on the topic.

OBJECTIVE

To assess the efficacy of IL 5-FU in the treatment of NMSC.

METHODS AND MATERIALS

A systematic review was performed using PubMed, Embase and Web of Science databases. 19 studies were included. ANOVA test was used to compare the duration of lesion prior to therapy and resolution time following IL 5-FU treatment. A two-way proportion test was performed to compare the clearance rate between squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and keratoacanthoma (KA).

RESULTS

There was no significant difference between the clearance rate of SCC and BCC after IL 5-FU therapy (87 % vs 91.4%, respectively; P=0.2); however, the clearance rate of both SCC and BCC was significantly greater than that of KA (74.5%; P&lt;0.007); 95% CI [2.56%&ndash;19.1%]. Lesion duration and resolution time did not significantly differ across SCC, BCC, and KA (P&gt;0.3).

CONCLUSION

While majority of data is derived from individual cases, IL 5-FU achieved higher clearance rate in SCC and BCC groups than in KA group. J Drugs Dermatol. 2021;20(2):192-198. doi:10.36849/JDD.5518.

Topical Application of Glycerol Increases Penetration Depth of Optical Coherence Tomography in Diagnosis of Basal Cell Carcinoma

Optical coherence tomography is a non-invasive imaging technique that enables high-resolution in vivo imaging of skin. Although optical coherence tomography is promising for diagnosing basal cell carcinoma, its limited penetration depth may impede basal cell carcinoma subtyping. This study evaluated whether topical application of glycerol can increase penetration depth and improve the image quality and visibility of characteristic features of basal cell carcinoma. A total of 61 patients with a total of 72 basal cell carcinomas were included. Optical coherence tomography scans were obtained before and after application of an 85% glycerol solution. The mean penetration depth of each optical coherence tomography scan was acquired by automatically tracing both skin surface and the point of signal loss using a custom-made MATLAB program. Mean±standard deviation penetration depth increased from 883 ± 108 to 904 ± 88 μm before and after glycerol application, respectively (p = 0.005). Topical application of glycerol leads to a significant 2.4% increase in penetration depth. However, no significant differences in image quality and visibility of basal cell carcinoma features were found.

Rapid and exceptional response to Sonidegib in a patient with multiple locally advanced basal cell carcinomas

Locally advanced basal cell carcinoma (laBCC) represents a rare but possible occurrence in the vast scenario of dermatological diseases. It is well known that most BCC has a pathological activation of the hedgehog pathway, making them susceptible to targeted therapy with selective inhibitors. Sonidegib, approved for the treatment of laBCC on the basis of the results of the basal cell carcinoma outcomes with LDE225 treatment study, demonstrated rapid efficacy and a manageable safety profile. Here, we describe the case of a patient affected by multiple laBCC treated with Sonidegib. The patient experienced an important regression of tumors after only 2 months of therapy, with few side effects. This result confirms the role of Sonidegib as a valid and well-tolerated therapeutic option for laBCC.

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.

A Vismodegib Experience in Elderly Patients with Basal Cell Carcinoma: Case Reports and Review of the Literature

Cutaneous basal cell carcinoma (BCC) is the most common type of human tumor, and its incidence rate is increasing worldwide. Up until a few years ago, therapeutic options have been limited for patients with advanced BCC (including metastatic and locally-advanced BCC). Over the last few years, promising systemic therapies have been investigated for the treatment of advanced BCC. In particular, the Hedgehog signaling inhibition has shown remarkable results for this population. Hedgehog inhibitors, represented by vismodegib and sonidegib, have been approved by the Food and Drug Administration and the European Medicines Agency for the treatment of both locally advanced and metastatic BCC, with, generally, a good safety profile. Notwithstanding the late onset of BCC in the global population, associated with life expectancy increase, only a few clinical trials have evaluated the efficacy and safety profile of Hedgehog inhibitors in this complex and neglected population. Herein, we review the major mechanisms implicated in the pathogenesis of BCC focusing on the Hedgehog signaling pathway and its therapeutic role in the elderly population. Finally, we report two case reports of BCC elderly patients in order to demonstrate both efficacy and safety of the Hedgehog inhibitors.

Anti-PD-1 antibody therapy for epithelial skin malignancies: An investigator-initiated, open-label, single-arm, multicenter, phase II clinical trial (NMSC-PD1 Study)

INTRODUCTION

Malignant cutaneous epithelial tumors comprise various skin malignancies originating from the cutaneous epithelium, including cutaneous squamous cell carcinoma, basal cell carcinoma, and malignant cutaneous adnexal tumors. Treatment options are limited, as the rarity of these tumors, especially among Asians, renders well-controlled clinical trials extremely challenging to conduct. Thus, we designed a clinical trial to evaluate the efficacy and safety of the anti-programmed cell death-1 (PD-1) monoclonal antibody nivolumab in patients with metastatic cutaneous squamous cell carcinomas and other rare metastatic cutaneous epithelial tumors.

METHODS AND ANALYSIS

This is an open-label, single-arm, multicenter, phase 2 clinical trial involving patients with metastatic malignant cutaneous epithelial tumors. Nivolumab (480 mg) will be administered intravenously every 4 weeks for a maximum of 26 doses. The primary outcome of the study will be the response rate based on response evaluation criteria in solid tumors, version 1.1. Assuming a null hypothesis of a response rate ≤5% and an alternative hypothesis of a 25% response rate, a minimum of 26 patients are required to achieve a 5% two-sided type I error and 80% power based on the exact binomial distribution. Finally, a target cohort size of 30 patients was determined as some patient dropout will be expected.

DISCUSSION

This is the first phase 2 clinical trial evaluating the efficacy and safety of the PD-1 inhibitor nivolumab in Asian patients with metastatic malignant cutaneous epithelial tumors. The findings of the study will contribute to the development of novel treatment approaches for patients with rare cutaneous malignancies, which remains an unmet clinical need.

TRIAL REGISTRATION

Registry number: jRCT 2031190048.

Basal Cell Carcinoma: A Comprehensive Review

Basal cell carcinoma (BCC) is the most common type of carcinoma worldwide. BCC development is the result of a complex interaction between environmental, phenotypic and genetic factors. However, despite the progress in the field, BCC biology and mechanisms of resistance against systemic treatments have been poorly investigated. The aim of the present review is to provide a revision of BCC histological and molecular features, including microRNA (miRNA) dysregulation, with a specific focus on the molecular basis of BCC systemic therapies. Papers from the last ten years regarding BCC genetic and phenotypic alterations, as well as the mechanism of resistance against hedgehog pathway inhibitors vismodegib and sonidegib were included. The involvement of miRNAs in BCC resistance to systemic therapies is emerging as a new field of knowledge.

Non-Melanoma Skin Cancers: Biological and Clinical Features

Non-melanoma skin cancers (NMSCs) include basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and Merkel cell carcinoma (MCC). These neoplasms are highly diverse in their clinical presentation, as well as in their biological evolution. While the deregulation of the Hedgehog pathway is commonly observed in BCC, SCC and MCC are characterized by a strikingly elevated mutational and neoantigen burden. As result of our improved understanding of the biology of non-melanoma skin cancers, innovative treatment options including inhibitors of the Hedgehog pathway and immunotherapeutic agents have been recently investigated against these malignancies, leading to their approval by regulatory authorities. Herein, we review the most relevant biological and clinical features of NMSC, focusing on innovative treatment approaches.

Outcomes of Vismodegib for Periocular Locally Advanced Basal Cell Carcinoma From an Open-label Trial

Importance

The outcomes of vismodegib treatment in a relatively large cohort of study participants with periocular locally advanced basal cell carcinoma (POLA-BCC) may guide physicians when considering this treatment.

Objective

To report the outcomes of vismodegib treatment in patients with POLA-BCC in the Safety Events in Vismodegib (STEVIE) study.

Design, Setting, and Participants

This post hoc subgroup analysis from the STEVIE single-arm, multicenter, open-label cohort study screened all 1215 participants for ocular or periocular involvement and identified 244 participants with POLA-BCC or metastatic BCC. Data for the first STEVIE trial were collected from 167 treatment locations in 36 countries from June 30, 2011, to June 14, 2017. This post hoc analysis was performed from April 1 to August 31, 2019.

Main Outcomes and Measures

Response to treatment and adverse events.

Results

Ocular or periocular involvement was found in 244 of 1215 STEVIE participants (20.1%), who constituted the analytic sample. The median age of the study participants was 72.0 (interquartile range [IQR], 60.0-82.0]) years, and they included 143 men (58.6%). Locally advanced BCC was diagnosed in 238 of the 244 participants (97.5%) and metastatic BCC, in 6 (2.5%). The median duration of exposure to vismodegib was 40.0 (IQR, 20.0-78.0) weeks, specifically 39.7 (IQR, 19.9-76.0) weeks for POLA-BCC and 92.4 (IQR, 53.2-163.0) weeks for metastatic BCC. Sixty-nine participants (28.3%) sustained serious adverse events (alopecia, muscle spasms, dysgeusia, weight loss, decreased appetite, asthenia, ageusia, nausea, fatigue, and diarrhea). Two hundred thirty-two study participants (95.1%) sustained more than 1 adverse effect. The overall mean (SD) number of drug-related adverse effects per study participant by first adverse event, regardless of the severity, was 5.48 (3.84). Discontinuation of vismodegib treatment owing to an adverse event was recorded in 58 participants (23.8%). During the study, 22 participants (9.0%) died, 70 (28.7%) achieved complete response, and 94 (38.5%) achieved partial response.

Conclusions and Relevance

Vismodegib was well tolerated by the study participants with POLA-BCC. The safety of vismodegib treatment according to the STEVIE trial findings is consistent with that reported in previous studies. These data may be helpful when considering vismodegib for patients with POLA-BCC.

In Search of a Phosphorus Dendrimer-Based Carrier of Rose Bengal: Tyramine Linker Limits Fluorescent and Phototoxic Properties of a Photosensitizer

Photodynamic therapy (PDT) is a skin cancer treatment alternative to chemotherapy and radiotherapy. This method exploits three elements: a phototoxic compound (photosensitizer), light source and oxygen. Upon irradiation by light of a specific wavelength, the photosensitizer generates reactive oxygen species triggering the cascade of reactions leading to cell death. The positive therapeutic effect of PDT may be limited due to low solubility, low tumor specificity and inefficient cellular uptake of photosensitizers. A promising approach to overcome these obstacles involves the use of nanocarrier systems. The aim of this initial study was to determine the potential of the application of phosphorus dendrimers as carriers of a photosensitizer—rose bengal (RB). The primary goal involved the synthesis and in vitro studies of covalent drug–dendrimer conjugates. Our approach allowed us to obtain RB–dendrimer conjugates with the use of tyramine as an aromatic linker between the carrier and the drug. The compounds were characterized by FT-IR, ¹H NMR, ¹³C NMR, ³¹P NMR, size and zeta potential measurements and spectrofluorimetric analysis. The dialysis to check the drug release from the conjugate, flow cytometry to specify intracellular uptake, and singlet oxygen generation assay were also applied. Finally, we used MTT assay to determine the biological activity of the tested compounds. The results of our experiments indicate that the conjugation of RB to phosphorus dendrimers via the tyramine linker decreases photodynamic activity of RB.

Regular Application of Sunscreen Can Prevent Skin Cancer

This review summarizes the evidence on the protection against skin cancer afforded by sunscreen. Solid evidence can come only from randomized controlled trials, despite a multitude of case-control and cohort studies that have addressed the issue, because observational evidence is intractably confounded since those at highest risk of skin cancer are naturally the highest users of sunscreen. Findings of the single human trial conducted in subtropical Australia during 1992-1996 with follow-up to 2014 showed that the application of a broad-spectrum, sun protection factor 16 sunscreen to exposed skin of the head and neck and upper limbs at least 3-4 days per week in adulthood can reduce the risk of developing cutaneous squamous cell carcinoma and melanoma but does not appear to reduce the risk of basal cell carcinoma (BCC) overall, although it may reduce the occurrence of multiple BCCs over time.