Pharmacokinetics and pharmacodynamics of Hedgehog pathway inhibitors used in the treatment of advanced or treatment-refractory basal cell carcinoma

INTRODUCTION

Sonidegib and vismodegib are currently the only US Food and Drug Administration and European Medicines Agency-approved small-molecule Hedgehog pathway inhibitors (HHIs)for treating adults with advanced or refractory basal cell carcinoma (BCC) that is not amenable to conventional surgery or radiotherapy. At this time, there are no head-to-head clinical trials comparing these two HHIs for efficacy and safety to assist clinicians with determining which HHI may be best suited for their patients.

AREAS COVERED

This review briefly describes the pathogenesis of BCC, provides a detailed overview of the key pharmacokinetic profile differences between sonidegib and vismodegib, explains their pharmacodynamics, and highlights the therapeutic considerations when either HHI is used to treat special patient populations.

EXPERT OPINION

Although both HHIs act at the same molecular target in the Hedgehog pathway, there are significant differences in their pharmacokinetic profiles that may play a potential role in their efficacy and safety. Evidence-based recommendations serve to inform clinicians until direct comparative clinical trials of sonidegib versus vismodegib are conducted to determine the clinical relevance of the reported differences in their pharmacokinetic properties.

Swiss Recommendations for Cutaneous Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common nonmelanoma skin cancer in Switzerland and worldwide. Most BCCs can be treated in a curative setting. However, patients can develop locally destructive and, rarely, metastatic tumors that require a different treatment approach. The clinical subtype of individual lesions provides prognostic information and influences management decisions. Surgical excision, topical therapies, and radiotherapy are highly effective in the majority of subtypes as well as in low- and high-risk diseases. For patients with low-risk diseases and superficial tumors not amenable to surgery, several nonsurgical alternatives are available. Systemic therapy is indicated for high-risk BCCs, which are not amenable to either surgery or radiotherapy. Hedgehog pathway inhibitors (HHI) are currently approved. Other therapeutic options such as immune checkpoint inhibitors show promising results in clinical trials. This first version of Swiss recommendations for diagnosis and management of BCC was prepared through extensive literature review and an advisory board consensus of expert dermatologists and oncologists in Switzerland. The present guidelines recommend therapies based on a multidisciplinary team approach and rate of recurrence for individual lesions. Based on the risk of recurrence, two distinct groups have been identified: low-risk (easy-to-treat) and high-risk (difficult-to-treat) tumors. Based on these classifications, evidence-based recommendations of available therapies are presented herein.

Vismodegib in Locally Advanced Basal Cell Carcinoma in Slovenia

BACKGROUND

Vismodegib is a first-in-class inhibitor of the hedgehog pathway for treatment of locally advanced basal cell carcinoma (laBCC) and metastatic BCC.

OBJECTIVES

The purpose of this study is to report outcomes of patients with laBCC, with basal cell carcinoma nevus syndrome (Gorlin Goltz syndrome [G-G Syn]) treated with vismodegib in routine clinical practice in Slovenia in 8.3-year period.

METHODS

In this retrospective cohort study, we analyzed baseline characteristics, outcomes, and treatment-related adverse events from locally advanced BCC. The patients were divided into two cohorts: 39 laBCC or multiple BCC patients and 7 patients with G-G Syn who were treated with vismodegib from November 2012 till January 2021.

RESULTS

During 100-month period, 46 patients were diagnosed with laBCC (26), multiple BCC (13), and G-G Syn (7), all inappropriate for surgery or radiotherapy. Baseline characteristics: median age was 72.8 years in laBCC + multiple BCC cohort and 47.4 years in G-G Syn cohort. The objective response rate was 80% in laBCC + multiple BCC and 86% in G-G Syn cohort. Disease control rate (DCR) was 95% in laBCC + multiple BCC and 100% in G-G Syn cohort. Median duration of treatment was 9.9 months (range: 1.5-43.1) in laBCC and multiple BCC cohort and 19.5 months (range: 3.6-94.1) in G-G Syn cohort. Majority of treatment-emergent adverse events (TEAEs) in laBCC or multiple BCC cohort were grade 1 or 2 (96%), only 4% of AEs were grade 3. Majority of TEAEs in G-G Syn cohort were also grade 1 or 2 (87%), 13% of AEs were grade 3. No grade 4 or 5 vismodegib-related AEs were reported.

CONCLUSION

Vismodegib has shown meaningful efficacy with DCR from 95% to 100% in patients with laBCC, multiple BCC, and G-G Syn in Slovenia. TEAEs were successfully alleviated with multidisciplinary approach and early supportive care.

Hedgehog pathway inhibitor real-world treatment patterns in patients with basal cell carcinoma: a claims-based analysis

Aims: To examine real-world treatment patterns for Hedgehog pathway inhibitors (HHIs) for the treatment of advanced basal cell carcinoma. Patients & methods: HHI initiators between January 2013 and June 2019 were identified from IBM MarketScan^® claims data. Time to treatment discontinuation and reinitiation were estimated using Kaplan-Meier methods using a 60-day grace period. Results: Among 526 patients with basal cell carcinoma who initiated an HHI, median time to first discontinuation was 144 days, and risk of discontinuation by 12 months was 88.0%. Probability of reinitiation within 12 months was 19.7%, and median time to second discontinuation was 118 days. Conclusion: HHI discontinuation was common and reinitiation uncommon in clinical practice. Future research should evaluate persistence with recently approved therapies.

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.

Casein Kinase 1D Encodes a Novel Drug Target in Hedgehog-GLI-Driven Cancers and Tumor-Initiating Cells Resistant to SMO Inhibition

Simple Summary

Uncontrolled activation of hedgehog (HH)—GLI signaling contributes to the development of several human malignancies. Targeted inhibition of the HH—GLI signaling cascade with small-molecule inhibitors can reduce cancer growth, but patient relapse is very common due to the development of drug resistance. Therefore, a high unmet medical need exists for new drug targets and inhibitors to achieve efficient and durable responses. In the current study, we identified CSNK1D as a novel drug target in the HH—GLI signaling pathway. Genetic and pharmacological inhibition of CSNK1D activity leads to suppression of oncogenic HH—GLI signaling, even in cancer cells in which already approved HH inhibitors are no longer effective due to resistance mechanisms. Inhibition of CSNK1D function reduces the malignant properties of so-called tumor-initiating cells, thereby limiting cancer growth and presumably metastasis. The results of this study form the basis for the development of efficient CSNK1D inhibitors for the therapy of HH—GLI-associated cancers.

Abstract

(1) Background: Aberrant activation of the hedgehog (HH)—GLI pathway in stem-like tumor-initiating cells (TIC) is a frequent oncogenic driver signal in various human malignancies. Remarkable efficacy of anti-HH therapeutics led to the approval of HH inhibitors targeting the key pathway effector smoothened (SMO) in basal cell carcinoma and acute myeloid leukemia. However, frequent development of drug resistance and severe adverse effects of SMO inhibitors pose major challenges that require alternative treatment strategies targeting HH—GLI in TIC downstream of SMO. We therefore investigated members of the casein kinase 1 (CSNK1) family as novel drug targets in HH—GLI-driven malignancies. (2) Methods: We genetically and pharmacologically inhibited CSNK1D in HH-dependent cancer cells displaying either sensitivity or resistance to SMO inhibitors. To address the role of CSNK1D in oncogenic HH signaling and tumor growth and initiation, we quantitatively analyzed HH target gene expression, performed genetic and chemical perturbations of CSNK1D activity, and monitored the oncogenic transformation of TIC in vitro and in vivo using 3D clonogenic tumor spheroid assays and xenograft models. (3) Results: We show that CSNK1D plays a critical role in controlling oncogenic GLI activity downstream of SMO. We provide evidence that inhibition of CSNK1D interferes with oncogenic HH signaling in both SMO inhibitor-sensitive and -resistant tumor settings. Furthermore, genetic and pharmacologic perturbation of CSNK1D decreases the clonogenic growth of GLI-dependent TIC in vitro and in vivo. (4) Conclusions: Pharmacologic targeting of CSNK1D represents a novel therapeutic approach for the treatment of both SMO inhibitor-sensitive and -resistant tumors.

Sonidegib in the Treatment of Locally Advanced Basal Cell Carcinoma

Sonidegib is an antagonist of the transmembrane protein Smoothened in the Hedgehog signaling pathway. It is indicated for the treatment of locally advanced basal cell carcinoma (BCC) that is not amenable to curative surgery or radiotherapy. Sonidegib's efficacy and safety were demonstrated in the phase 2 BOLT trial, where 61% (95% CI, 48-72%) of patients with locally advanced BCC treated with sonidegib 200 mg achieved an objective response to treatment with a mean time to response of 4 months. The median duration of response was 26.1 months and the median progression-free survival was 22.1 months. The most common adverse events were muscle spasms (54.4%), hair loss (49.4%), and loss of taste (44.3%); most events were grade 1 or 2. In this review, we summarize the main findings on the efficacy, safety, and tolerability of sonidegib and discuss the management of locally advanced BCC with this drug.

Targeted Therapies for Pediatric AML: Gaps and Perspective

Acute myeloid leukemia (AML) is a hematopoietic disorder characterized by numerous cytogenetic and molecular aberrations that accounts for ~25% of childhood leukemia diagnoses. The outcome of children with AML has increased remarkably over the past 30 years, with current survival rates up to 70%, mainly due to intensification of standard chemotherapy and improvements in risk classification, supportive care, and minimal residual disease monitoring. However, childhood AML prognosis remains unfavorable and relapse rates are still around 30%. Therefore, novel therapeutic approaches are needed to increase the cure rate. In AML, the presence of gene mutations and rearrangements prompted the identification of effective targeted molecular strategies, including kinase inhibitors, cell pathway inhibitors, and epigenetic modulators. This review will discuss several new drugs that recently received US Food and Drug Administration approval for AML treatment and promising strategies to treat childhood AML, including FLT3 inhibitors, epigenetic modulators, and Hedgehog pathway inhibitors.

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.

Structure-Activity Relationship Studies of Vitamin D3 Analogues Containing an Ether or Thioether Linker as Hedgehog Pathway Inhibitors

The Hedgehog (Hh) signaling pathway is critical for embryonic patterning and postembryonic tissue regeneration. Constitutive pathway activation has also been linked to human malignancies such as basal cell carcinoma (BCC) and medulloblastoma; therefore, multiple small-molecule scaffolds that inhibit Hh signaling are in development. Previously, Grundmann's alcohol, also known as the "northern region" of vitamin D3 (VD3), has been identified as a moderate Hh pathway inhibitor. In this study, isomers of Grundmann's alcohol with different orientations of the C4 hydroxy group and C3α proton were investigated to determine the optimal configuration for this hexahydroindane scaffold with respect to Hh inhibition. A series of analogues containing Grundmann's alcohol linked to a substituted phenyl or benzyl ring through an ether or thioether linker were synthesized and evaluated for their anti-Hh activity. Of these, analogue 17 ((1R,3aR,4R,7aR)-1-[(R)-1,5-dimethylhexyl]-4-(4-aminophenoxy)-7a-methyloctahydro-1H-indene) demonstrated potent anti-Hh activity in Hh-dependent BCC cells and did not activate canonical vitamin D receptor signaling, demonstrating its selective nature for the Hh signaling pathway.

Advanced Basal Cell Carcinoma: Epidemiology and Therapeutic Innovations

Advanced basal cell carcinomas are a subset of basal cell carcinomas that can be difficult to treat either due to their local invasiveness, proximity to vital structures, or metastasis. The incidence of all basal cell carcinoma is increasing in the United States, although it is not known whether advanced basal cell carcinomas (aBCCs) are also increasing. Recently, highly targeted therapy based on knowledge of the basal cell carcinoma pathogenesis has become available either commercially or through human clinical trials. These orally available drugs inhibit the Hedgehog signaling pathway, and lead to advanced basal cell carcinoma shrinkage that can enable preservation of adjacent vital organs. In this review, we outline the role of Hedgehog pathway inhibitors as well as other treatment modalities such as excision, radiotherapy and more traditional chemotherapy in treating advanced basal cell carcinomas. We also highlight current gaps in knowledge regarding the use and side effects of this targeted therapy.

Targeted therapy for advanced Basal-cell carcinoma: vismodegib and beyond

Basal-cell carcinoma is a commonly occurring skin malignancy that has the potential to progress into locally invasive or resistant disease, as well as spread distantly. Due to advances in the molecular understanding of the disease over the last two decades, it has been discovered that the Hedgehog pathway plays an important role in the pathogenesis of this disease and can be exploited as a treatment target. Several agents that inhibit the Hedgehog pathway have reached clinical studies and one drug, vismodegib, has recently been US Food and Drug Administration (FDA) approved based on clinical activity and tolerability in patients with advanced basal-cell carcinoma. This review will describe the clinical development of vismodegib, as well as the proper application of the drug in clinical practice. Other important clinical questions, such as mechanisms of resistance to vismodegib and the role of other Hedgehog pathway inhibitors currently in development will also be discussed.