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Although smoothened inhibitors (SMOi) have demonstrated efficacy in the management of basal cell carcinoma, no guidelines are available on how to utilize SMOi in the treatment of Gorlin syndrome (GS). This review's objective is to assess the clinical response to SMOi in GS, provide practical guidance for clinicians, and identify areas for future research. Through comprehensive searches of previous publications and expert opinion, this review demonstrates that intermittent dosing of SMOi and daily dosing have similar efficacy. While the adverse events of SMOi may result in their discontinuation during treatment of GS, intermittent dosing may improve compliance., Competing Interests: Conflicts of interest None disclosed., (Copyright © 2024 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Abstract: Targeting the mammalian target of rapamycin (mTOR) pathway represents a potentially novel approach to treat basal cell carcinoma (BCC), but activation of this pathway has not been well described in human BCCs. The purpose of this study was to assess whether mTOR pathway activation occurs in BCCs (both sporadic and syndromic) and report a case of a patient with Gorlin syndrome (GS) whose clinically suspicious BCCs responded to mTOR inhibition through topical sirolimus treatment. After Stanford Institutional Review Board Approval, archived BCCs from patients with GS (n = 25), sporadic BCCs (n = 35), and control tissues were subjected to immunohistochemical analysis for the activation of mTOR pathway, and immunohistochemical staining intensity was evaluated by a dermatopathologist. BCCs (compared with normal skin) had elevated levels of eIF4EBP1 ( Padjusted = 0.0336), which is downstream of mTOR. a serine/threonine kinase Phospho-(AKT), which interacts with mTOR, was also significantly elevated (perinuclear: Padjusted < 0.0001; cytoplasmic: Padjusted = 0.0021). When off-label topical 1% sirolimus was used on a pediatric patient with GS, we noted reduction of new BCC development and decreased size of existing neoplasms clinically suspicious for BCCs. This treatment was well tolerated after 2 years of continuous use, with no other treatments needed during this period. Topical sirolimus is a promising therapeutic candidate against both sporadic and GS-associated BCC. Multicenter, prospective studies are needed to understand the efficacy and safety of topical mTOR inhibitors in BCC treatment, and ascertain whether the immunohistochemical markers downstream of mTOR could have predictive value in identifying BCCs most likely to respond to topical mTOR inhibitors, such as sirolimus., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Treatment with Hedgehog Inhibitors in Gorlin-Goltz syndrome (GGS) yields favourable objective clinical responses, yet secondary resistance and class-related toxicity restrict treatment duration. This study aims to review current data on GGS patients undergoing vismodegib therapy, focusing on treatment duration, clinical outcomes and schedule modifications. A systematic search of the PubMed database was conducted for English articles from 1993 to 2023, identifying 31 papers suitable for inclusion. A total of 351 patients, with a mean age of 52 years, were analysed. The average treatment duration was 9.3 months for patients who discontinued treatment, and 25.1 months for those who continued vismodegib at the time this study was published. Vismodegib achieved a complete response rate of 44%. Treatment interruption predominantly occurred due to side effects (69.1%) and secondary resistance (9.1%). The use of alternative regimens, although not compromising efficacy, may enhance treatment compliance. Further investigations are warranted to ascertain the optimal treatment regimen and timeline for GGS patients. Schedule modifications offer promise in ameliorating side effects and facilitating long-term treatment., (© 2024 Australasian College of Dermatologists.)

Although basal cell carcinomas arise from ectopic Hedgehog pathway activation and can be treated with pathway inhibitors, sporadic basal cell carcinomas display high resistance rates, whereas tumors arising in patients with Gorlin syndrome with germline Patched (PTCH1) alterations are uniformly suppressed by inhibitor therapy. In rare cases, patients with Gorlin syndrome on long-term inhibitor therapy will develop individual resistant tumor clones that rapidly progress, but the basis of this resistance remains unstudied. In this study, we report a case of an SMO inhibitor-resistant tumor arising in a patient with Gorlin syndrome on suppressive SMO inhibitor for nearly a decade. Using a combination of multiomics and spatial transcriptomics, we define the tumor populations at the cellular and tissue level to conclude that Gorlin tumors can develop resistance to SMO inhibitors through the previously described basal to squamous cell carcinoma transition. Intriguingly, through spatial whole-exome genomic analysis, we nominate PCYT2, ETNK1, and the phosphatidylethanolamine biosynthetic pathway as genetic suppressors of basal to squamous cell carcinoma transition resistance. These observations provide a general framework for studying tumor evolution and provide important clinical insight into mechanisms of resistance to SMO inhibitors for not only Gorlin syndrome but also sporadic basal cell carcinomas., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)