Single and multiple dose intravenous and oral pharmacokinetics of the hedgehog pathway inhibitor vismodegib in healthy female subjects

Evaluation of the Tolerability of Hedgehog Pathway Inhibitors in the Treatment of Advanced Basal Cell Carcinoma: A Narrative Review of Treatment Strategies

Hedgehog pathway inhibitors (HHIs) have broadened the treatment options available for patients with advanced basal cell carcinoma (BCC) for whom traditional therapeutic approaches are not feasible or effective. Sonidegib and vismodegib are oral HHIs that were approved for treatment of patients with advanced BCC after demonstrating promising efficacy in the pivotal Phase II BOLT (NCT01327053) and ERIVANCE (NCT00833417) trials, respectively. However, the incidence and types of treatment-emergent adverse events (AEs) observed with these agents may limit continuous use of HHIs and ultimately impact clinical outcomes. In this review, we summarize the safety and tolerability profiles of sonidegib and vismodegib and discuss potential management strategies for HHI class-effect AEs, including muscle spasms, creatine phosphokinase increase, alopecia, and dysgeusia. These AEs primarily occur early in treatment and can lead to treatment discontinuation. Differences in the pharmacokinetic profiles of sonidegib and vismodegib may contribute to the variability noted in times to onset and resolution of these and other AEs. Evidence suggests that protocol modifications, such as treatment interruptions and dose reductions, are effective ways to manage AEs while maintaining disease control. Nonpharmacologic and pharmacologic interventions may also be considered as part of an AE management strategy. Overall, healthcare providers and patients with advanced BCC should be aware of the HHI class-effect AEs and plan effective management strategies to avoid treatment discontinuation and optimize therapeutic response.

Upholding or Breaking the Law of Superposition in Pharmacokinetics

The law of superposition underpins first-order linear pharmacokinetic relationships. Most drugs, therefore, after a single dose can be described by first-order or linear processes, which can be superposed to understand multiple-dose regimen behavior. However, there are a number of situations where drugs could display behaviors after multiple dosing that leads to capacity-limited or saturation non-linear kinetics and the law of superposition is overruled. This review presents a practical guide to understand the equations and calculations for single and multiple-dosing regimens after intravenous and oral administration. It also provides the pharmaceutical basis for saturation in ADME processes and the consequent changes in the area under the concentration-time curve, which represents drug exposure that can lead to the modulation of efficacy and/or toxic effects. The pharmacokineticist must implicitly understand the principles of superposition, which are a central tenet of drug behavior and disposition during drug development.

The application of Phase 0 and microtracer approaches in early clinical development: past, present, and future

Phase 0 microdosing studies were introduced to the drug development community approximately 20 years ago. A microdose is defined as less than 1/100th of the dose calculated based on animal data to yield a pharmacological effect in humans, with a maximum of 100 μg, or 30 nmoles for protein products. In our experience, Phase 0 microdose studies have not been fully embraced by the pharmaceutical industry. This notion is based on the number of Phase 0 studies that we have been involved in. Thus, we conducted at least 17 Phase 0 microdose studies in the Zero's (on average, two per year), but in the years beyond this, it was only 15 studies (1.4 per year); in these latter years, we did conduct a total of 23 studies which employed an intravenous (i.v.) microdose for absolute bioavailability (ABA) assessments (two per year on average), which are the most used and potentially informative type of clinical study using a microdose, albeit they are formally not microdose studies. In the current review, we summarize the past use of and experience with Phase 0 microdose designs in early clinical development, including intravenous 14C microdose ABA studies, and assess what is needed to increase the adoption of useful applications of Phase 0/microdose studies in the near future.

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.

Plasma Protein-Mediated Uptake and Contradictions to the Free Drug Hypothesis: A Critical Review

According to the free drug hypothesis (FDH), only free, unbound drug is available to interact with biological targets. This hypothesis is the fundamental principle that continues to explain the vast majority of all pharmacokinetic and pharmacodynamic processes. Under the FDH, the free drug concentration at the target site is considered the driver of pharmacodynamic activity and pharmacokinetic processes. However, deviations from the FDH are observed in hepatic uptake and clearance predictions, where observed unbound intrinsic hepatic clearance (CL_int,u) is larger than expected. Such deviations are commonly observed when plasma proteins are present and form the basis of the so-called plasma protein-mediated uptake effect (PMUE). This review will discuss the basis of plasma protein binding as it pertains to hepatic clearance based on the FDH, as well as several hypotheses that may explain the underlying mechanisms of PMUE. Notably, some, but not all, potential mechanisms remained aligned with the FDH. Finally, we will outline possible experimental strategies to elucidate PMUE mechanisms. Understanding the mechanisms of PMUE and its potential contribution to clearance underprediction is vital to improving the drug development process.

The current clinical approach to difficult-to-treat basal cell carcinomas

INTRODUCTION

Basal cell carcinoma (BCC) is the most common malignant tumor in adult white populations. If BCCs are not treated for years, if they cause massive destruction of the surrounding tissues, if they are considered unresectable or not eligible for radiotherapy they become progressively 'locally advanced' (laBCC) or metastatic (mBCC). These tumors are defined as 'difficult-to-treat BCC.'

AREAS COVERED

A comprehensive search on PubMed was conducted to identify relevant literature about the several approved and recommended treatment options for the management of difficult-to-treat BCC published from January 2012 to July 2022. Surgical options, radiotherapy, hedgehog inhibitors, immunotherapy, and combined treatments are discussed. The keywords used were basal cell carcinoma; difficult-to-treat BCC; management of difficult-to-treat BCC; surgical therapy; radiotherapy; hedgehog inhibitors; immunotherapy.

EXPERT OPINION

Identifying the best approach to DTT BCCs is one of the main challenges for the dermato-oncologist. The introduction of HHI for the treatment of advanced BCCs has revolutionized the clinical management of DTT BCCs. The immune checkpoint inhibitor cemiplimab has been approved for the treatment of locally advanced or metastatic BCC refractory to HHI therapy or in patients intolerant to HHI therapy. Multidisciplinary teams (MDTs) play a key role in managing these complex patients.

Using drug scheduling to manage adverse events associated with hedgehog pathway inhibitors for basal cell carcinoma

Basal cell carcinoma (BCC) is the most common malignancy and form of skin cancer worldwide; advanced BCC, either as locally advanced BCC (laBCC) or metastatic BCC (mBCC), can cause substantial tissue invasion and morbidity. Until the recent availability of the hedgehog pathway inhibitors (HHIs) sonidegib and vismodegib, treatment options for advanced BCC were limited. These agents demonstrate efficacy in patients with laBCC and mBCC; however, the adverse events (AEs) associated with these agents can lead to treatment interruption or discontinuation and reduced quality of life, all of which significantly impact long-term adherence to therapy, which might affect clinical outcome. Given that most AEs are class-related effects, switching HHIs does not appear to lead to a significantly different AE profile, underscoring the importance of maintaining patients on their first HHI. Interrupting treatment of sonidegib and vismodegib does not appear to undermine the efficacy of these agents and is therefore a practical option to manage AEs in order to maintain continued treatment and disease control.

Evaluation of Hedgehog Pathway Inhibition on Nevoid Basal Cell Carcinoma Syndrome Fibroblasts and Basal Cell Carcinoma-Associated Fibroblasts: Are Vismodegib and Sonidegib Useful to Target Cancer-Prone Fibroblasts?

Activating mutations in the Hh pathway underlies the development of sporadic and familial skin BCC. For these oncogenic proliferations displaying ligand-independent activation of the intracellular pathway, two molecules have been approved for therapeutic purposes: vismodegib and sonidegib. Improper Hh signalling occurs in many human tumours also via a paracrine mechanism (ligand-dependent) in which the secretion of Hh ligands by stromal cells support tumour growth. On the other hand, the mobilization of neoplastic stroma by cancer cells is sustained by the activation of Hh signalling in surrounding fibroblasts suggesting a central role of this bidirectional crosstalk in carcinogenesis. Additionally, loss-of-function mutations in the PTCH1 gene in the context of NBCCS, an autosomal dominant disorder predisposing to multiple BCCs, determine tumour permissive phenotypes in dermal fibroblasts. Here, profiling syndromic and BCC-associated fibroblasts unveiled an extraordinary similarity characterized by overexpression of several Hh target genes and a marked pro-inflammatory outline. Both cell types exposed to Hh inhibitors displayed reversion of the tumour-prone phenotype. Under vismodegib and sonidegib treatment, the Wnt/β-catenin pathway, frequently over-active in tumour stroma, resulted down-regulated by pAKT-GSK3β axis and consequent increase of β-catenin turnover. Overall, this study demonstrated that vismodegib and sonidegib impacting on fibroblast tumour supportive functions might be considered in therapy for BCC independently to the mutation status of Hh components in neoplastic cells.

Poly(2-oxazoline) nanoparticle delivery enhances the therapeutic potential of vismodegib for medulloblastoma by improving CNS pharmacokinetics and reducing systemic toxicity

We report a nanoparticle formulation of the SHH-pathway inhibitor vismodegib that improves efficacy for medulloblastoma, while reducing toxicity. Limited blood-brain barrier (BBB) penetration and dose-limiting extitle/citraneural toxicities complicate systemic therapies for brain tumors. Vismodegib is FDA-approved for SHH-driven basal cell carcinoma, but implementation for medulloblastoma has been limited by inadequate efficacy and excessive bone toxicity. To address these issues through optimized drug delivery, we formulated vismodegib in polyoxazoline block copolymer micelles (POx-vismo). We then evaluated POx-vismo in transgenic mice that develop SHH-driven medulloblastomas with native vasculature and tumor microenvironment. POx-vismo improved CNS pharmacokinetics and reduced bone toxicity. Mechanistically, the nanoparticle carrier did not enter the CNS, and acted within the vascular compartment to improve drug delivery. Unlike conventional vismodegib, POx-vismo extended survival in medulloblastoma-bearing mice. Our results show the broad potential for non-targeted nanoparticle formulation to improve systemic brain tumor therapy, and specifically to improve vismodegib therapy for SHH-driven cancers.

Sonidegib for the Treatment of Advanced Basal Cell Carcinoma

Basal cell carcinoma (BCC) accounts for almost 80% of skin cancers, and its healthcare workload burden is substantial within dermatology departments. Although most BCCs are small, well-defined tumors amenable of surgery or conservative procedures, in a small proportion of patients, BCCs can progress to an advanced stage including locally advanced BCC. The goal of the clinician in the treatment of BCC should be the right therapeutic approach at diagnosis, and different guidelines propose treatment strategies in order to prevent relapses or disease progression. In case of unresectable and untreatable BCC with radiotherapy, the first-choice medical therapy is Hedgehog-GLI (HH) pathway inhibitors. Sonidegib was approved by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) as a first-line treatment for adult patients with locally advanced BCC, becoming the second HH pathway inhibitor receiving approval after vismodegib. In this review, data on pharmacology, safety, tolerability, and efficacy of sonidegib are summarized and compared to those of vismodegib. Lastly, indications on the management of advanced basal cell carcinoma based on author’s clinical experience are provided.

A Physiologically Based Pharmacokinetic Model of Vismodegib: Deconvoluting the Impact of Saturable Plasma Protein Binding, pH-Dependent Solubility and Nonsink Permeation

Vismodegib displays unique pharmacokinetic characteristics including saturable plasma protein binding to alpha-1 acid glycoprotein (AAG) and apparent time-dependent bioavailability leading to non-linear PK with dose and time, significantly faster time to steady-state and lower than predicted accumulation. Given these unique characteristics, a PBPK model was developed to explore mechanistic insights into saturable protein binding and complex oral absorption processes and de-convolute the impact of these independent non-linear processes on vismodegib exposure. Simcyp V18 was used for model development; oral absorption was characterized using the multi-layer gut wall (M-ADAM) model and mechanistic permeability model, incorporating transport across an unstirred boundary layer (UBL) between the luminal fluid and enterocyte in each segment of the gastrointestinal tract. PBPK simulations were compared with observed PK data from clinical trials in oncology patients and healthy subjects. Saturation of vismodegib protein binding to AAG led to substantially lower total drug accumulation, time to steady-state, and Css_total. For free exposure, Css_free and accumulation were unchanged, but time to steady-state was substantially reduced. Vismodegib oral absorption declined with both dose and dosing frequency; the concentration gradient driving vismodegib oral absorption declined with multiple doses, leading to a 32% decrease in vismodegib f_a from first dose to steady-state. Fed simulations suggested that increased solubility and dissolution are partially offset by reduced permeability across the UBL due to slower diffusion of micelle-bound drug. This work demonstrates the value of PBPK modeling to simultaneously capture and de-convolute multi-faceted absorption and disposition processes and provide mechanistic insights for compounds with complex pharmacokinetics.

A Phase 1b Study of Vismodegib with Pirfenidone in Patients with Idiopathic Pulmonary Fibrosis

INTRODUCTION

Components of the hedgehog signaling pathway are upregulated in patients with idiopathic pulmonary fibrosis (IPF). Vismodegib, a small-molecule inhibitor of hedgehog signaling, when used in combination with currently available antifibrotic therapy, may be more efficacious than antifibrotics alone. The objective of this study was to evaluate the safety and tolerability of vismodegib plus pirfenidone in patients with IPF.

METHODS

Twenty-one patients were enrolled in a phase 1b open-label trial to receive vismodegib 150 mg plus pirfenidone 2403 mg/day once daily. Key endpoints were safety, tolerability, and pharmacokinetics. Exploratory endpoints included change from baseline to week 24 in % predicted forced vital capacity (FVC) and University of California, San Diego Shortness of Breath Questionnaire (UCSD-SOBQ) scores, as well as pharmacodynamic changes in hedgehog biomarker C-X-C motif chemokine ligand 14 (CXCL14).

RESULTS

All patients reported at least one treatment-emergent adverse event (AE), most frequently muscle spasms (76.2%). Serious AEs were reported in 14.3% of patients; one event of dehydration was considered related to vismodegib. One patient died due to IPF progression, unrelated to either treatment. More patients discontinued vismodegib than pirfenidone (42.9% vs. 33.3%, respectively). Changes from baseline to week 24 in % predicted FVC and UCSD-SOBQ scores were within known endpoint variability. In contrast to findings in basal cell carcinoma, vismodegib had no effect on circulating CXCL14 levels.

CONCLUSION

The safety profile was generally consistent with the known profiles of both drugs, with no new safety signals observed in this small cohort. There was no pharmacodynamic effect on CXCL14 levels. Future development of vismodegib for IPF may be limited due to tolerability issues.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02648048. Plain language summary available for this article.

FUNDING

F. Hoffmann-La Roche Ltd. and Genentech, Inc.

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.

Pharmacokinetic and Pharmacodynamic Considerations for Drugs Binding to Alpha-1-Acid Glycoprotein

According to the free drug hypothesis only the unbound drug is available to act at physiological sites of action, and as such the importance of plasma protein binding primarily resides in its impact on pharmacokinetics and pharmacodynamics. Of the major plasma proteins, alpha-1-acid glycoprotein (AAG) represents an intriguing one primarily due to the high affinity, low capacity properties of this protein. In addition, there are marked species and age differences in protein expression, homology and drug binding affinity. As such, a thorough understanding of drug binding to AAG can help aid and improve the translation of pharmacokinetic/pharmacodynamic (PK/PD) relationships from preclinical species to human as well as adults to neonates. This review provides a comprehensive overview of our current understanding of the biochemistry of AAG; endogenous function, impact of disease, utility as a biomarker, and impact on PK/PD. Experimental considerations are discussed as well as recommendations for understanding the potential impact of AAG on PK through drug discovery and early development.

New developments in the treatment of basal cell carcinoma: update on current and emerging treatment options with a focus on vismodegib

Basal cell carcinoma (BCC) is the most common form of skin cancer worldwide. Although most BCCs can be treated by relatively simple surgical or nonsurgical methods, some patients with BCC may eventually develop advanced disease which can either be locally destructive or even include metastatic spread. The present review summarizes the current literature on the treatment of both early and advanced BCC with a focus on the hedgehog inhibitor vismodegib which has become an integral part of the management of patients with advanced BCC since its regulatory approval in 2012.

A survey of renal impairment pharmacokinetic studies for new oncology drug approvals in the USA from 2010 to early 2015: a focus on development strategies and future directions

The US Food and Drug Administration (FDA) issued a guidance document in 2010 on pharmacokinetic (PK) studies in renal impairment (RI) on the basis of observations that substances such as uremic toxins might result in altered drug metabolism and excretion. No specific recommendations for oncology drugs were included. We surveyed the publicly available FDA review documents of 29 small molecule oncology drugs approved between 2010 and the first quarter of 2015. The objectives were as follows: (i) summarize the impact of RI on PK at the time of the initial new drug application; (ii) identify limitations of the guidance; and (iii) outline an integrated approach to study the impact of RI on these drugs. Our survey indicates that the current FDA guidance does not appear to provide clear strategic or decision pathways for RI studies in terms of small molecule oncology drugs. The FDA review documents indicate an individualized approach to the review because of the complex pharmacologic nature of these drugs and patient populations. Overall, the strategy for carrying out a RI study during clinical development or as a postmarketing study requires integration with the totality of data, including mass balance, absolute bioavailability, drug–drug interaction, hepatic dysfunction, population PK, exposure–response analysis, the therapeutic window for best guidance, and determination of the optimal doses for special oncology populations.

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.

Adding value through accelerator mass spectrometry-enabled first in human studies

Accelerator mass spectrometry (AMS) is an ultra-sensitive technique for the analysis of radiocarbon. It is applicable to bioanalysis of any ¹⁴ C-labelled analyte and any sample type. The increasing body of data generated using LC+AMS indicates that the methodology is robust and reliable, and capable of meeting the same validation criteria as conventional bioanalytical techniques. Because it is a tracer technique, AMS is capable of discriminating between an administered radiolabelled dose and endogenous compound or non-radiolabelled compound administered separately. This paper discusses how it can be used to enhance the design of first in human (FIH) clinical studies and generate significant additional data, including: fundamental pharmacokinetics (CL and V), absolute bioavailability, mass balance, routes and rates of excretion, metabolic fate (including first-pass metabolism, identification of biliary metabolites and quantitative data to address metabolite safety testing issues), and tissue disposition of parent compound and metabolites. Because the ¹⁴ C-labelled microtracer dose is administered at the same time as a pharmacologically relevant non-radiolabelled dose, there is no concern about dose-linearity. However the mass of the microtracer dose itself is negligible and therefore does not affect the outcome of the FIH study. The addition of microtracer doses to a FIH study typically requires little additional expense, apart from the AMS analytics, making the approach cost-effective. It can also save significant time, compared to conventional approaches, and, by providing reliable human in vivo data as early as possible, prevent unnecessary expenditure later in drug development.

The synthesis of [(14) C]AZD5122. Incorporation of an IV (14) C-microtracer dose into a first in human study to determine the absolute oral bioavailability of AZD5122

AZD5122, N-(2-(2,3-difluorobenzylthio)-6-((2R,3R)-3,4-dihydroxybutan-2-ylamino)pyrimidin-4-yl)azetidine-1-sulfonamide was under investigation as a potential chemokine receptor CXCR2 antagonist for the treatment for inflammatory diseases. To gain a better understanding of the human pharmacokinetic profile, an exploratory phase I IV microtracer study was conducted using carbon-14 radiolabelled AZD5122. [(14) C]AZD5122 was carbon-14 labelled in the pyrimidine ring in five steps in an overall radiochemical yield of 19% from [(14) C]thiourea. The absolute oral bioavailability of AZD5122 was assessed in healthy subjects by an oral administration of AZD5122, followed by a concomitant intravenous [(14) C]AZD5122 microdose.

Absorption, distribution, metabolism and excretion (ADME) of the ALK inhibitor alectinib: results from an absolute bioavailability and mass balance study in healthy subjects

1. Alectinib is a highly selective, central nervous system-active small molecule anaplastic lymphoma kinase inhibitor. 2. The absolute bioavailability, metabolism, excretion and pharmacokinetics of alectinib were studied in a two-period single-sequence crossover study. A 50 μg radiolabelled intravenous microdose of alectinib was co-administered with a single 600 mg oral dose of alectinib in the first period, and a single 600 mg/67 μCi oral dose of radiolabelled alectinib was administered in the second period to six healthy male subjects. 3. The absolute bioavailability of alectinib was moderate at 36.9%. Geometric mean clearance was 34.5 L/h, volume of distribution was 475 L and the hepatic extraction ratio was low (0.14). 4. Near-complete recovery of administered radioactivity was achieved within 168 h post-dose (98.2%) with excretion predominantly in faeces (97.8%) and negligible excretion in urine (0.456%). Alectinib and its major active metabolite, M4, were the main components in plasma, accounting for 76% of total plasma radioactivity. In faeces, 84% of dose was excreted as unchanged alectinib with metabolites M4, M1a/b and M6 contributing to 5.8%, 7.2% and 0.2% of dose, respectively. 5. This novel study design characterised the full absorption, distribution, metabolism and excretion properties in each subject, providing insight into alectinib absorption and disposition in humans.

Mechanistic investigations into the species differences in pinometostat clearance: impact of binding to alpha-1-acid glycoprotein and permeability-limited hepatic uptake

1. The plasma clearance of the first-in-class DOT1L inhibitor, EPZ-5676 (pinometostat), was shown to be markedly lower in human compared to the preclinical species, mouse, rat and dog. 2. This led to vertical allometry where various interspecies scaling methods were applied to the data, with fold-errors between 4 and 13. We had previously reported the elimination and metabolic pathways of EPZ-5676 were similar across species. Therefore, the aim of this work was to explore the mechanistic basis for the species difference in clearance for EPZ-5676, focusing on other aspects of disposition. 3. The protein binding of EPZ-5676 in human plasma demonstrated a non-linear relationship suggesting saturable binding at physiologically relevant concentrations. Saturation of protein binding was not observed in plasma from preclinical species. Kinetic determinations using purified serum albumin and alpha-1-acid glycoprotein (AAG) confirmed that EPZ-5676 is a high affinity ligand for AAG with a dissociation constant (K_d) of 0.24 μM. 4. Permeability limited uptake was also considered since hepatocyte CL_int was much lower in human relative to preclinical species. Passive unbound CL_int for EPZ-5676 was estimated using a correlation analysis of logD and data previously reported on seven drugs in sandwich cultured human hepatocytes. 5. Incorporation of AAG binding and permeability limited hepatic uptake into the well-stirred liver model gave rise to a predicted clearance for EPZ-5676 within 2-fold of the observed value of 1.4 mL min^-1kg^-1. This analysis suggests that the marked species difference in EPZ-5676 clearance is driven by high affinity binding to human AAG as well as species-specific hepatic uptake invoking the role of transporters.

A clinical drug-drug interaction study to evaluate the effect of a proton-pump inhibitor, a combined P-glycoprotein/cytochrome 450 enzyme (CYP)3A4 inhibitor, and a CYP2C9 inhibitor on the pharmacokinetics of vismodegib

PURPOSE

The Hedgehog pathway inhibitor vismodegib exhibits pH-dependent solubility, and in vitro studies have shown that vismodegib is a substrate of P-glycoprotein (P-gp) and is metabolized by cytochrome P450 (CYP) 2C9 and 3A4. The objective of this four-arm parallel study in healthy subjects was to evaluate the effect of the proton-pump inhibitor rabeprazole, the P-gp/CYP3A4 inhibitor itraconazole, and the CYP2C9 and 3A4 inhibitor fluconazole on vismodegib steady-state pharmacokinetics.

METHODS

Cohorts included a control arm (n = 22), in which vismodegib 150 mg was administered once daily (QD) for 7 days, and 3 arms in which vismodegib was co-administered QD for 7 days with rabeprazole 20 mg (including a 4-day lead-in; n = 24); itraconazole 200 mg (n = 22); or fluconazole 400 mg (n = 22).

RESULTS

Area under the vismodegib concentration-time curve from zero to 24 h (AUC0-24h) at steady state was lower with concomitant rabeprazole administration relative to vismodegib alone [geometric mean ratio (GMR), 86.2 (associated 90 % confidence interval [CI], 76.1, 97.7)]. There was no effect of itraconazole on steady-state exposure of vismodegib [GMR, 96.4 (90 % CI 84.9, 109.6)]. Co-administration with fluconazole increased vismodegib steady-state AUC0-24h [GMR, 130.9 (90 % CI 115.2, 148.7)]. Co-administration of rabeprazole, itraconazole, and fluconazole had similar effects on the exposure of unbound vismodegib and total vismodegib.

CONCLUSION

The results of this study suggest that vismodegib can be administered with acid-reducing agents and P-gp and CYP inhibitors without the risk of a clinically meaningful pharmacokinetic drug-drug interaction. CLINICALTRIALS.

GOV IDENTIFIER

NCT01772290.

Basal Cell Carcinoma: A Comprehensive Review of Existing and Emerging Nonsurgical Therapies

Basal cell carcinoma is the most commonly occurring cancer in the world and overall incidence is still on the rise. While typically a slow-growing tumor for which metastases is rare, basal cell carcinoma can be locally destructive and disfiguring. Given the vast prevalence of this disease, there is a significant overall burden on patient well-being and quality of life. The current mainstay of basal cell carcinoma treatment involves surgical modalities, such as electrodessication and curettage, excision, cryosurgery, and Mohs micrographic surgery. Such methods are typically reserved for localized basal cell carcinoma and offer high five-year cure rates, but come with the risk of functional impairment, disfigurement, and scarring. Here, the authors review the evidence and indications for nonsurgical treatment modalities in cases where surgery is impractical, contraindicated, or simply not desired by the patient.

Opportunities in low-level radiocarbon microtracing: applications and new technology

¹⁴C-radiolabeled (radiocarbon) drug studies are central to defining the disposition of therapeutics in clinical development. Concerns over radiation, however, have dissuaded investigators from conducting these studies as often as their utility may merit. Accelerator mass spectrometry (AMS), originally designed for carbon dating and geochronology, has changed the outlook for in-human radiolabeled testing. The high sensitivity of AMS affords human clinical testing with vastly reduced radiative (microtracing) and chemical exposures (microdosing). Early iterations of AMS were unsuitable for routine biomedical use due to the instruments' large size and associated per sample costs. The situation is changing with advances in the core and peripheral instrumentation. We review the important milestones in applied AMS research and recent advances in the core technology platform. We also look ahead to an entirely new class of ¹⁴C detection systems that use lasers to measure carbon dioxide in small gas cells.

A comprehensive review of the role of the hedgehog pathway and vismodegib in the management of basal cell carcinoma

BACKGROUND

Basal cell carcinoma (BCC) is the most common cancer. Most cases of BCCs are treated with only optimal surgical resection. However, unresectable, locally advanced or metastatic tumors might have potential to progress. In this patient group, there is no standardized treatment approach. Vismodegib is a new selective inhibitor of the hedgehog (Hh) pathway. This manuscript is aimed to review the efficacy of the Hh pathway inhibitor vismodegib in BCC patients with locally advanced or metastatic disease.

SCOPE

Vismodegib showed positive results in clinical studies. A computerized search of the PubMed and American Society of Clinical Oncology Meeting abstracts was performed, by searching for the following keywords: 'vismodegib', 'pathway', 'inhibitor', and 'targeted therapies for BCC'. The last search was done on 1 September 2014. Most of the vismodegib data depend on phase I and II trials.

FINDINGS

Preclinical and clinical studies have shown that Hh pathway activation occurs in BCC. In BCC patients the role of chemotherapy is not completely known. Although conventional chemotherapies like cisplatins increase the response rate in BCC, improvement in overall survival and progression free survival were not demonstrated. Results of both phase I and phase II studies have shown that vismodegib is a potential new treatment strategy for patients with locally advanced and metastatic BCC. As in previously published phase I trials, in the ERIVANCE BCC study the primary endpoint, objective response rate, significantly increased by 43% and 30% in patients with locally advanced and metastatic BCC, respectively. Because of the promising results in phase I and II trials, vismodegib was approved by the Food and Drug Administration (FDA) in the treatment of patients with BCC who are not suitable for surgery or radiotherapy or with relapsed locally advanced disease following surgery or metastatic disease.

CONCLUSION

Recent trials have shown that vismodegib has produced promising activity in patients with locally advanced and metastatic BCC. The ongoing studies with vismodegib in other solid tumors and BCC will shed light on more certain treatment pathways.

Application of a method used to deconstruct a single dose pharmacokinetic profile from multiple dose data

With traditional non-compartmental methods, it is challenging to deconstruct plasma concentration versus time curves to assess the influence of individual doses. This study describes the application of a mathematical approach used to deconstruct a single dose curve using data derived from the second, third, fourth or nth dosing interval. Using data from a prospective clinical trial it is demonstrated that this approach reliably estimates pharmacokinetic parameters measured following two doses of zolpidem tartrate. Additionally, the study demonstrates the application of this approach using previously published data from a single- and multiple-dose pharmacokinetic study of the antibiotic gatifloxacin. Copyright © 2015 John Wiley & Sons, Ltd.

Discovery and preclinical development of vismodegib

INTRODUCTION

Vismodegib is the first Hedgehog (Hh) pathway inhibitor approved in the US for the treatment of adults with metastatic or locally advanced basal cell carcinoma (BCC). It was approved by the US FDA on 30 January 2012, and by the European Commission on 12 July 2013, for the treatment of adult patients with symptomatic metastatic BCC, or locally advanced BCC inappropriate for surgery or radiotherapy. Vismodegib selectively inhibits the Hh signaling pathway, binding to and inhibiting a critical signal-transducing component of the pathway, Smoothened (SMO). Vismodegib was discovered by Genentech, Inc., under a collaboration agreement with Curis, Inc.

AREAS COVERED

This article reviews the development of vismodegib from its discovery, preclinical pharmacology and validation to the clinical pharmacokinetics and validation in Phase I and II clinical investigations. We also provide a survey of other Hh pathway inhibitors in clinical development.

EXPERT OPINION

The authors' experience in target-based drug discovery suggests that vismodegib's path to the clinic deserves some reflection to identify key steps that have contributed to its success. Targeting the Hh pathway with vismodegib blocks the abberant signaling caused by mutational inactivation of the negative regulator PTCH1 or mutational activation of SMO. Vismodegib gives physicians a treatment option for patients with locally advanced or metastatic BCC for whom surgery or radiation is not recommended.

Emerging drugs and combination strategies for basal cell carcinoma

INTRODUCTION

Basal cell carcinoma (BCC) is a malignancy that is driven by an activated Hedgehog (Hh) pathway. Smoothened inhibitors are a new promising treatment option for patients with locally advanced or metastatic BCC or basal cell nevus syndrome. But long-term data are still limited, the optimal treatment duration is not yet defined and there are already documented cases with acquired resistance.

AREAS COVERED

Treatment modalities with Hh inhibitors, side effects and potential pharmacological combination options are discussed. The current literature, including PubMed, Cochrane database and registered trials on ClinicalTrials.gov, was searched.

EXPERT OPINION

BCCs typically regress during therapy with Hh inhibitors. Muscle toxicity, dysgeusia and hair loss can be considered as on target adverse reactions. Muscle toxicity is the dose-limiting toxicity of sonidegib. It was not seen with vismodegib because of its high binding to plasma protein α-1-acid glycoprotein. Sonidegib is different and shows a clear dose-toxicity relationship, which allows to address the question of whether there is a dose dependency of regression rate, cure rate and progression-free survival. In addition, basic research has offered strategies to enhance efficacy by the combination with other molecules, such as EGFR inhibitors, MEK inhibitors or immunotherapy.

Vismodegib for the treatment of basal cell skin cancer

PURPOSE

The pharmacology, clinical efficacy, adverse effects, cost, and place in therapy of vismodegib are reviewed.

SUMMARY

Vismodegib, the first oral treatment for basal cell carcinoma (BCC), was recently approved for the treatment of patients with locally advanced or metastatic BCC whose cancer is refractory to standard treatments or who are not candidates for surgery or radiation. Vismodegib is a small molecule that potently inhibits signal transduction in the hedgehog signaling pathway, demonstrates nonlinear pharmacokinetics, and has a half-life of 13 days. Agents that increase gastrointestinal pH may reduce the solubility and bioavailability of vismodegib. It is effective in both locally advanced and metastatic BCCs, with response rates ranging from 30% to 60% in two clinical trials. Vismodegib is available as a 150-mg capsule, and the approved dosage is 150 mg orally once daily. The most common adverse effects of vismodegib include mild-to-moderate hair loss, muscle cramps, taste disturbance, and weight loss. The estimated cost of one month of treatment with vismodegib is $7500.

CONCLUSION

Vismodegib was recently approved for the treatment of locally advanced or metastatic BCC that is refractory to standard treatments or if patients are not candidates for surgery or radiation. Vismodegib may have little effect on the treatment of BCC, given its high cost, the high cure rates achieved with standard therapies, and its unacceptable toxicity profile in patients with a non-life-threatening disease. However, vismodegib's novel mechanism of action, oral dosage form, preliminary efficacy, and tolerability compared with cytotoxic chemotherapy may make it an attractive candidate for the treatment of other cancers.

Vismodegib: an inhibitor of the Hedgehog signaling pathway in the treatment of basal cell carcinoma

OBJECTIVE

To review vismodegib, the first Food and Drug Administration (FDA)-approved Hedgehog (Hh) signaling pathway inhibitor, in the treatment of advanced basal cell carcinoma (BCC).

DATA SOURCES

MEDLINE and PubMed were searched using the terms vismodegib, GDC-0449, RG3616, and basal cell carcinoma for relevant clinical trials through September 2013. The FDA Web site, the National Clinical Trials registry, and abstracts from the American Society of Clinical Oncology (ASCO) were also evaluated to identify unpublished data and future clinical trials.

STUDY SELECTION/DATA EXTRACTION

All identified clinical and preclinical studies published in the English language were assessed, including selected references from the bibliographies of articles.

DATA SYNTHESIS

Activation of the Hh signaling pathway is well documented in BCC. Vismodegib is a small-molecule inhibitor of Hh signaling that acts by antagonizing the protein Smoothened (SMO), thereby preventing downstream transcriptional activation of genes involved in cell proliferation and survival. Vismodegib was approved by the FDA in January 2012 for the treatment of recurrent, locally advanced BCC (laBCC), or metastatic BCC (mBCC) for which surgery or radiation cannot be utilized. A pivotal phase 2 trial evaluating 104 patients demonstrated that treatment with vismodegib, 150 mg orally once daily, resulted in a 30% and 43% objective response rate in patients with mBCC and laBCC, respectively. The most common adverse effects from vismodegib were mild to moderate and included muscle spasms, dysgeusia, decreased weight, fatigue, alopecia, and diarrhea. However, clinical studies noted a high incidence of discontinuation of therapy by patients for reasons other than disease progression.

CONCLUSIONS

The approval of vismodegib represents the only targeted, prospectively studied treatment option for patients with advanced BCC. Further research assessing the utility of vismodegib in the treatment of other malignancies and the development of resistance patterns will more clearly define the role of Hedgehog inhibition in the broader scheme of oncological disorders.

Evaluation of food effect on pharmacokinetics of vismodegib in advanced solid tumor patients

PURPOSE

Vismodegib, an orally bioavailable small-molecule Smoothened inhibitor, is approved for treatment of advanced basal cell carcinoma (BCC). We conducted a pharmacokinetic study of vismodegib in patients with advanced solid tumors to explore the effects of food on drug exposure.

EXPERIMENTAL DESIGN

In part I, patients were randomized to fasting overnight (FO), a high fat meal (HF), or a low fat meal (LF) before a single dose of vismodegib 150 mg. Plasma concentrations of vismodegib were determined by a validated liquid chromatography-tandem mass spectrometry assay. Primary endpoints were C(max) and area under the curve (AUC(0-168)). In part II, patients randomized to FO or HF in part I took vismodegib 150 mg daily after fasting; those randomized to LF took it after a meal. Primary endpoints after two weeks were C(max) and AUC(0-24).

RESULTS

Sixty (22 FO, 20 HF, 18 LF) and 52 (25 fasting, 27 fed) patients were evaluable for primary endpoints in parts I and II, respectively. Mean C(max) and AUC(0-168) after a single dose were higher in HF than FO patients [ratios of geometric means (90% CI) = 1.75 (1.30, 2.34) and 1.74 (1.25, 2.42), respectively]. There were no significant differences in C(max) or AUC(0-24) between fasting and fed groups after daily dosing. The frequencies of drug-related toxicities were similar in both groups.

CONCLUSIONS

A HF meal increases plasma exposure to a single dose of vismodegib, but there are no pharmacokinetic or safety differences between fasting and fed groups at steady-state. Vismodegib may be taken with or without food for daily dosing.

U.S. Food and Drug Administration approval: vismodegib for recurrent, locally advanced, or metastatic basal cell carcinoma

The data and regulatory considerations leading to the U.S. Food and Drug Administration (FDA) January 30, 2012 approval of Erivedge (vismodegib) capsules for the treatment of patients with recurrent, locally advanced, or metastatic basal cell carcinoma (BCC) are described. The FDA's approval decision was based primarily on the results observed in a single-arm, parallel cohort, international trial of vismodegib, administered orally at 150 mg daily until disease progression, in patients with pathologically confirmed, recurrent, locally advanced basal cell carcinoma (laBCC) or metastatic basal cell carcinoma (mBCC). An independent review committee confirmed an overall response rate (ORR) of 30.3% [95% confidence interval (CI): 15.6-48.2] in 33 patients with mBCC and an ORR of 42.9% (95% CI: 30.5-56.0) in 63 patients with laBCC; median response durations were 7.6 months and 7.6 months for patients with mBCC and laBCC, respectively. The most common adverse reactions were muscle spasms, alopecia, dysgeusia, weight loss, fatigue, nausea, diarrhea, decreased appetite, constipation, cough, arthralgias, vomiting, headache, ageusia, insomnia, and upper respiratory tract infection. Animal toxicology studies confirmed that vismodegib is a potent teratogenic agent. Approval was based on durable objective tumor responses supported by knowledge of the pathologic role of Hedgehog signaling in BCC and acceptable toxicity in a population without effective alternative therapies.

Vismodegib: in locally advanced or metastatic basal cell carcinoma

Vismodegib is the first Hedgehog pathway inhibitor to be approved in the US, where it is indicated for the treatment of adults with metastatic basal cell carcinoma (BCC), or with locally advanced BCC that has recurred following surgery or who are not candidates for surgery, and who are not candidates for radiation. Vismodegib selectively and potently inhibits the Hedgehog signalling pathway by binding to Smoothened, thereby inhibiting the activation of Hedgehog target genes. Oral vismodegib was effective in the treatment of patients with locally advanced (n = 63) or metastatic (n = 33) BCC, according to the results of an ongoing, noncomparative, multinational, pivotal, phase II trial (ERIVANCE BCC). In this trial (using a clinical cutoff date of 26 November 2010), the independent review facility overall response rate was 42.9% in patients with locally advanced BCC and 30.3% in patients with metastatic BCC. In both patients with locally advanced BCC and those with metastatic BCC, the median duration of response was 7.6 months and median progression-free survival was 9.5 months. Oral vismodegib had an acceptable tolerability profile in patients with advanced BCC.