Population pharmacokinetics and exposure-response of trametinib, a MEK inhibitor, in patients with BRAF V600 mutation-positive melanoma

Tyrosine kinase inhibitors in cancers: Treatment optimization - Part II

Real-life populations are more heterogeneous than those included in prospective clinical studies. In cancer patients, comorbidities and co-medications favor the appearance of severe adverse effects which can significantly impact quality of life and treatment effectiveness. Most of tyrosine kinase inhibitors (TKI) have been developed with flat oral dosing exposing patients to the risk of poor adherence due to side effects. Additionally, genetic or physiological factors, differences in diet, and drug-drug interactions can lead to inter-individual variability affecting treatment outcomes and increasing the risk of adverse events. Knowledge of the different factors of variability allows individualized patient management. This review examines the effects of adherence, food intake, and pharmaceutical form on the pharmacokinetics of oral TKI, as well as evaluating pharmacokinetics considerations improving TKI management. Concentration-effectiveness and concentration-toxicity data are presented for the selected TKI, and a simple therapeutic drug monitoring schema is outlined to help individualize dosing of oral TKI.

Topical trametinib for epidermal and sebaceous nevi in a child with Schimmelpenning-Feuerstein-Mims syndrome

We present the case of a 20-month-old girl with Schimmelpenning-Feuerstein-Mims (SFM) syndrome with extensive head, neck, and torso skin involvement successfully managed with topical trametinib. Trametinib interferes downstream of KRAS and HRAS in the MAPK signaling pathway, of which KRAS was implicated in our child's pathogenic variant. Although other dermatologic conditions have shown benefit from oral trametinib, its topical use has not been well reported. Our patient showed benefit from the use of twice-daily topical trametinib, applied to the epidermal and sebaceous nevi over a 16-month period, leading to decreased pruritus and thinning of the plaques.

Are novel oral oncolytics underdosed in obese patients?

PURPOSE

Data on the effects of obesity on drug exposure of oral targeted oncolytics is scarce. Therefore, the aim of this study was to investigate the influence of body weight and body mass index (BMI) on trough levels of oral oncolytics with an exposure-response relationship. The oral oncolytics of interest were abiraterone, alectinib, cabozantinib, crizotinib, imatinib, pazopanib, sunitinib and trametinib.

METHODS

This retrospective cohort study included patients treated with the selected oral oncolytics at the standard dose, with a measured trough level at steady state and with available body weight. The Spearman's correlation test was used to determine the correlation between body weight and trough levels. The Fisher's exact text was used to compare the frequency of inadequate trough levels between BMI categories.

RESULTS

1265 patients were included across the different oral oncolytics. A negative correlation coefficient was observed between weight and trough levels for crizotinib (n = 75), imatinib (n = 201) and trametinib (n = 310), respectively, ρ = - 0.41, ρ = - 0.24 and ρ = - 0.23, all with a p-value < 0.001. For crizotinib, a higher percentage of patients with a body weight > 100 kg had inadequate trough levels. No statistically significant differences were observed in the frequency of inadequate trough levels between BMI categories.

CONCLUSION

Higher body weight was only correlated with lower plasma trough levels for crizotinib, imatinib, and trametinib. Therefore, patients with a high body weight may require dose escalation to obtain adequate target levels when treated with these oral oncolytics.

Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Although kinase inhibitors (KI) frequently portray large interpatient variability, a 'one size fits all' regimen is still often used. In the meantime, relationships between exposure-response and exposure-toxicity have been established for several KIs, so this regimen could lead to unnecessary toxicity and suboptimal efficacy. Dose adjustments based on measured systemic pharmacokinetic levels-i.e., therapeutic drug monitoring (TDM)-could therefore improve treatment efficacy and reduce the incidence of toxicities. Therefore, the aim of this comprehensive review is to give an overview of the available evidence for TDM for the 77 FDA/EMA kinase inhibitors currently approved (as of July 1st, 2023) used in hematology and oncology. We elaborate on exposure-response and exposure-toxicity relationships for these kinase inhibitors and provide practical recommendations for TDM and discuss corresponding pharmacokinetic targets when possible.

A phase I trial of the pan-ERBB inhibitor neratinib combined with the MEK inhibitor trametinib in patients with advanced cancer with EGFR mutation/amplification, HER2 mutation/amplification, HER3/4 mutation or KRAS mutation

PURPOSE

Aberrant alterations of ERBB receptor tyrosine kinases lead to tumorigenesis. Single agent therapy targeting EGFR or HER2 has shown clinical successes, but drug resistance often develops due to aberrant or compensatory mechanisms. Herein, we sought to determine the feasibility and safety of neratinib and trametinib in patients with EGFR mutation/amplification, HER2 mutation/amplification, HER3/4 mutation and KRAS mutation.

METHODS

Patients with actionable somatic mutations or amplifications in ERBB genes or actionable KRAS mutations were enrolled to receive neratinib and trametinib in this phase I dose escalation trial. The primary endpoint was determination of the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT). Secondary endpoints included pharmacokinetic analysis and preliminary anti-tumor efficacy.

RESULTS

Twenty patients were enrolled with a median age of 50.5 years and a median of 3 lines of prior therapy. Grade 3 treatment-related toxicities included: diarrhea (25%), vomiting (10%), nausea (5%), fatigue (5%) and malaise (5%). The MTD was dose level (DL) minus 1 (neratinib 160 mg daily with trametinib 1 mg, 5 days on and 2 days off) given 2 DLTs of grade 3 diarrhea in DL1 (neratinib 160 mg daily with trametinib 1 mg daily). The treatment-related toxicities of DL1 included: diarrhea (100%), nausea (55.6%) and rash (55.6%). Pharmacokinetic data showed trametinib clearance was significantly reduced leading to high drug exposures of trametinib. Two patients achieved stable disease (SD) ≥ 4 months.

CONCLUSION

Neratinib and trametinib combination was toxic and had limited clinical efficacy. This may be due to suboptimal drug dosing given drug-drug interactions.

TRIAL REGISTRATION ID

NCT03065387.

Exposure-response analyses of BRAF- and MEK-inhibitors dabrafenib plus trametinib in melanoma patients

INTRODUCTION

Dabrafenib and trametinib are currently administered at fixed doses, at which interpatient variability in exposure is high. The aim of this study was to investigate whether drug exposure is related to efficacy and toxicity in a real-life cohort of melanoma patients treated with dabrafenib plus trametinib.

PATIENTS AND METHODS

An observational study was performed in which pharmacokinetic samples were collected as routine care. Using estimated dabrafenib Area Under the concentration-time Curve and trametinib trough concentrations (C_min), univariable and multivariable exposure-response analyses were performed.

RESULTS

In total, 140 patients were included. Dabrafenib exposure was not related to either progression-free survival (PFS) or overall survival (OS). Trametinib exposure was related to survival, with C_min ≥ 15.6 ng/mL being identified as the optimal threshold. Median OS was significantly longer in patients with trametinib C_min ≥ 15.6 ng/mL (22.8 vs. 12.6 months, P = 0.003), with a multivariable hazard ratio of 0.55 (95% CI 0.36-0.85, P = 0.007). Median PFS in patients with trametinib C_min levels ≥ 15.6 ng/mL (37%) was 10.9 months, compared with 6.0 months for those with C_min below this threshold (P = 0.06). Multivariable analysis resulted in a hazard ratio of 0.70 (95% CI 0.47-1.05, P = 0.082). Exposure to dabrafenib and trametinib was not related to clinically relevant toxicities.

CONCLUSIONS

Overall survival of metastasized melanoma patients with trametinib C_min levels ≥ 15.6 ng/mL is ten months longer compared to patients with C_min below this threshold. This would theoretically provide a rationale for therapeutic drug monitoring of trametinib. Although a high proportion of patients are underexposed, there is very little scope for dose increments due to the risk of serious toxicity.

In Vitro/In Vivo Translation of Synergistic Combination of MDM2 and MEK Inhibitors in Melanoma Using PBPK/PD Modelling: Part III

The development of in vitro/in vivo translational methods and a clinical trial framework for synergistically acting drug combinations are needed to identify optimal therapeutic conditions with the most effective therapeutic strategies. We performed physiologically based pharmacokinetic-pharmacodynamic (PBPK/PD) modelling and virtual clinical trial simulations for siremadlin, trametinib, and their combination in a virtual representation of melanoma patients. In this study, we built PBPK/PD models based on data from in vitro absorption, distribution, metabolism, and excretion (ADME), and in vivo animals' pharmacokinetic-pharmacodynamic (PK/PD) and clinical data determined from the literature or estimated by the Simcyp simulator (version V21). The developed PBPK/PD models account for interactions between siremadlin and trametinib at the PK and PD levels. Interaction at the PK level was predicted at the absorption level based on findings from animal studies, whereas PD interaction was based on the in vitro cytotoxicity results. This approach, combined with virtual clinical trials, allowed for the estimation of PK/PD profiles, as well as melanoma patient characteristics in which this therapy may be noninferior to the dabrafenib and trametinib drug combination. PBPK/PD modelling, combined with virtual clinical trial simulation, can be a powerful tool that allows for proper estimation of the clinical effect of the above-mentioned anticancer drug combination based on the results of in vitro studies. This approach based on in vitro/in vivo extrapolation may help in the design of potential clinical trials using siremadlin and trametinib and provide a rationale for their use in patients with melanoma.

The Combination of Trametinib and Ganitumab is Effective in RAS-Mutated PAX-Fusion Negative Rhabdomyosarcoma Models

PURPOSE

PAX-fusion negative rhabdomyosarcoma (FN RMS) is driven by alterations in the RAS/MAP kinase pathway and is partially responsive to MEK inhibition. Overexpression of IGF1R and its ligands is also observed in FN RMS. Preclinical and clinical studies have suggested that IGF1R is itself an important target in FN RMS. Our previous studies revealed preclinical efficacy of the MEK1/2 inhibitor, trametinib, and an IGF1R inhibitor, BMS-754807, but this combination was not pursued clinically due to intolerability in preclinical murine models. Here, we sought to identify a combination of an MEK1/2 inhibitor and IGF1R inhibitor, which would be tolerated in murine models and effective in both cell line and patient-derived xenograft models of RAS-mutant FN RMS.

EXPERIMENTAL DESIGN

Using proliferation and apoptosis assays, we studied the factorial effects of trametinib and ganitumab (AMG 479), a mAb with specificity for human and murine IGF1R, in a panel of RAS-mutant FN RMS cell lines. The molecular mechanism of the observed synergy was determined using conventional and capillary immunoassays. The efficacy and tolerability of trametinib/ganitumab was assessed using a panel of RAS-mutated cell-line and patient-derived RMS xenograft models.

RESULTS

Treatment with trametinib and ganitumab resulted in synergistic cellular growth inhibition in all cell lines tested and inhibition of tumor growth in four of six models of RAS-mutant RMS. The combination had little effect on body weight and did not produce thrombocytopenia, neutropenia, or hyperinsulinemia in tumor-bearing SCID beige mice. Mechanistically, ganitumab treatment prevented the phosphorylation of AKT induced by MEK inhibition alone. Therapeutic response to the combination was observed in models without a mutation in the PI3K/PTEN axis.

CONCLUSIONS

We demonstrate that combined trametinib and ganitumab is effective in a genomically diverse panel of RAS-mutated FN RMS preclinical models. Our data also show that the trametinib/ganitumab combination likely has a favorable tolerability profile. These data support testing this combination in a phase I/II clinical trial for pediatric patients with relapsed or refractory RAS-mutated FN RMS.

Therapeutic Drug Monitoring of Protein Kinase Inhibitors in the Treatment of Non-small Cell Lung Cancer

Targeted therapy with protein kinase inhibitors (PKIs) represents one of the important treatment options for non-small cell lung cancer (NSCLC). It has contributed to improve patients' survival and quality of life significantly. These anticancer drugs are administrated orally in flat-fixed doses despite the well-known large interpatient pharmacokinetic variability and the possible need for dose individualization. To optimize and individualize dosing of PKIs, and thereby increasing the effectiveness and safety of the treatment, therapeutic drug monitoring (TDM) is the most frequently mentioned method. Unlike other areas of medicine, TDM has been rather exceptional in oncological practise since there is a little evidence or no data for concentration-effect relationships of PKIs. Therefore, the aim of this review is to summarize the pharmacokinetic characteristics of PKIs and provide the evidence supporting the use of TDM for personalised treatment of patients with NSCLC.

Identification of an ergosterol derivative with anti-melanoma effect from the sponge-derived fungus Pestalotiopsis sp. XWS03F09

It is difficult to treat malignant melanoma because of its high malignancy. New and effective therapies for treating malignant melanoma are urgently needed. Ergosterols are known for specific biological activities and have received widespread attention in cancer therapy. Here, LH-1, a kind of ergosterol from the secondary metabolites of the marine fungus Pestalotiopsis sp., was extracted, isolated, purified, and further investigated the biological activities against melanoma. In vitro experiments, the anti-proliferation effect on tumor cells was detected by MTT and colony formation assay, and the anti-metastatic effect on tumor cells was investigated by wound healing assay and transwell assay. Subcutaneous xenograft models, histopathology, and immunohistochemistry have been used to verify the anti-tumor, toxic, and side effect in vivo. Besides, the anti-tumor mechanism of LH-1 was studied by mRNA sequencing. In vitro, LH-1 could inhibit the proliferation and migration of melanoma cells A375 and B16-F10 in a dose-dependent manner and promote tumor cell apoptosis through the mitochondrial apoptosis pathway. In vivo assays confirmed that LH-1 could suppress melanoma growth by inducing cell apoptosis and reducing cell proliferation, and it did not have any notable toxic effects on normal tissues. LH-1 may play an anti-melanoma role by upregulating OBSCN gene expression. These findings suggest that LH-1 may be a potential for the treatment of melanoma.

Monitoring of Dabrafenib and Trametinib in Serum and Self-Sampled Capillary Blood in Patients with BRAFV600-Mutant Melanoma

Patients treated with dabrafenib and trametinib for BRAFV600-mutant melanoma often experience dose reductions and treatment discontinuations. Current knowledge about the associations between patient characteristics, adverse events (AE), and exposure is inconclusive. Our study included 27 patients (including 18 patients for micro-sampling). Dabrafenib and trametinib exposure was prospectively analyzed, and the relevant patient characteristics and AE were reported. Their association with the observed concentrations and Bayesian estimates of the pharmacokinetic (PK) parameters of (hydroxy-)dabrafenib and trametinib were investigated. Further, the feasibility of at-home sampling of capillary blood was assessed. A population pharmacokinetic (popPK) model-informed conversion model was developed to derive serum PK parameters from self-sampled capillary blood. Results showed that (hydroxy-)dabrafenib or trametinib exposure was not associated with age, sex, body mass index, or toxicity. Co-medication with P-glycoprotein inducers was associated with significantly lower trough concentrations of trametinib (p = 0.027) but not (hydroxy-)dabrafenib. Self-sampling of capillary blood was feasible for use in routine care. Our conversion model was adequate for estimating serum PK parameters from micro-samples. Findings do not support a general recommendation for monitoring dabrafenib and trametinib but suggest that monitoring can facilitate making decisions about dosage adjustments. To this end, micro-sampling and the newly developed conversion model may be useful for estimating precise PK parameters.

Pharmacokinetics and therapeutic drug monitoring of anticancer protein/kinase inhibitors

Over the past two decades, protein/kinase inhibitors, as targeted therapies, raised in number and have become increasingly mainstream in the treatment of malignant diseases, thanks to the ease of oral administration and the minimal adverse drug reactions. These drugs have similar pharmacokinetic properties: a relatively good absorption and distribution, a strong hepatic metabolism, and a mainly biliary excretion. However, this pharmacokinetic and route of administration has the disadvantage of resulting in a large inter- and intra-individual variability. Despite this significant variability, these drugs are largely prescribed at the same initial dose for quite all patients (flat dose), even though this variability would require individualized adaptation for each patient and/or each new circumstance. Promptly after their commercialization, scientific teams have performed concentration measurements of several drugs and showed the existence of efficacy or toxicity thresholds. This has contributed to the development of therapeutic drug monitoring as one of the strategies to improve the response and reduce the adverse reactions of these drugs. There is still a need to determine precise thresholds for the remaining drugs and to evaluate the impact of TDM in therapeutic management. In order to determine the current state of the art, this article reviews indications, pharmacokinetics and TDM data for 49 marketed PKIs.

Phase I pharmacokinetic study of single agent trametinib in patients with advanced cancer and hepatic dysfunction

BACKGROUND

Trametinib is an oral MEK 1/2 inhibitor, with a single agent recommended phase 2 dose (RP2D) of 2 mg daily (QD). This study was designed to evaluate RP2D, maximum tolerated dose (MTD), and pharmacokinetic (PK) profile of trametinib in patients with advanced solid tumors who had various degrees of hepatic dysfunction (HD).

METHODS

Advanced cancer patients were stratified into 4 HD groups based on Organ Dysfunction Working Group hepatic function stratification criteria: normal (Norm), mild (Mild), moderate (Mod), severe (Sev). Dose escalation was based on "3 + 3" design within each HD group. PK samples were collected at cycle 1 days 15-16.

RESULTS

Forty-six patients were enrolled with 44 evaluable for safety [Norm=17, Mild=7, Mod (1.5 mg)=4, Mod (2 mg)=5, Sev (1 mg)=9, Sev (1.5 mg)=2] and 22 for PK analysis. Treatment related adverse events were consistent with prior trametinib studies. No treatment related deaths occurred. Dose limiting toxicities (DLTs) were evaluable in 15 patients (Mild=6, Mod (1.5 mg)=3, Mod (2 mg)=2, Sev (1 mg)=3 and Sev (1.5 mg)=1). One DLT (grade 3 acneiform rash) was observed in a Sev patient (1.5 mg). Dose interruptions or reductions due to treatment related adverse events occurred in 15 patients (34%) [Norm=9, 53%; Mild=2, 29%; Mod (1.5 mg)=1, 33%; Mod (2 mg)=2, 33%; Sev (1 mg)=1, 11%; Sev (1.5 mg)=1; 50%]. There were no significant differences across HD groups for all PK parameters when trametinib was normalized to 2 mg. However, only limited PK data were available for the Mod (n = 3) and Sev (n = 3) groups compared to Norm (n = 10) and Mild (n = 6) groups. Trametinib is heavily protein bound, with no correlation between serum albumin level and unbound trametinib fraction (p = 0.26).

CONCLUSIONS

RP2D for trametinib in Mild HD patients is 2 mg QD. There are insufficient number of evaluable patients due to difficulty of patient accrual to declare RP2D and MTD for Mod and Sev HD groups. DLTs were not observed in the highest dose cohorts that reached three evaluable patients - 1.5 mg QD in Mod group, and 1 mg QD in Sev group.

TRIAL REGISTRATION

This study was registered in the ClinicalTrials.gov website ( NCT02070549 ) on February 25, 2014. .

Plexiform neurofibroma: shedding light on the investigational agents in clinical trials

INTRODUCTION

Neurofibromatosis Type 1 (NF1) is an autosomal dominant genetic condition, which predisposes individuals to the development of plexiform neurofibromas (PN), benign nerve sheath tumors seen in 30-50% of patients with NF1. These tumors may cause significant pain and disfigurement or may compromise organ function. Given the morbidity associated with these tumors, therapeutic options for patients with NF1-related PN are necessary.

AREAS COVERED

We searched the www.clinicaltrials.gov database for 'plexiform neurofibroma.' This article summarizes completed and ongoing trials involving systemic therapies for PN.

EXPERT OPINION

Surgery is the mainstay treatment; however, complete resection is not possible in many cases. Numerous systemic therapies have been evaluated in patients with NF1, with MEK inhibitors (MEKi) showing the greatest efficacy for volumetric reduction and improvement in functional and patient-reported outcomes. The MEKi selumetinib is now FDA approved for the treatment of inoperable, symptomatic PN in pediatric NF1 patients. Questions remain regarding the use of this drug class in terms of when to initiate therapy, overall duration, reduced dosing schedules, and side effect management. Future studies are needed to fully understand the clinical application of MEKi and to evaluate other potential therapies through appropriate trial designs for this potentially devastating, manifestation in NF1.

Precision Dosing of Targeted Therapies Is Ready for Prime Time

Fixed dosing of oral targeted therapies is inadequate in the era of precision medicine. Personalized dosing, based on pharmacokinetic (PK) exposure, known as therapeutic drug monitoring (TDM), is rational and supported by increasing evidence. The purpose of this perspective is to discuss whether randomized studies are needed to confirm the clinical value of precision dosing in oncology. PK-based dose adjustments are routinely made for many drugs and are recommended by health authorities, for example, for patients with renal impairment or for drug-drug interaction management strategies. Personalized dosing simply extrapolates this paradigm from selected patient populations to each individual patient with suboptimal exposure, irrespective of the underlying cause. If it has been demonstrated that exposure is related to a relevant clinical outcome, such as efficacy or toxicity, and that exposure can be optimized by PK-guided dosing, it could be logically assumed that PK-guided dosing would result in better treatment outcomes without the need for randomized confirmatory trials. We propose a path forward to demonstrate the clinical relevance of individualized dosing of molecularly-targeted anticancer drugs.

Optimized Dosing: The Next Step in Precision Medicine in Non-Small-Cell Lung Cancer

In oncology, and especially in the treatment of non-small-cell lung cancer (NSCLC), dose optimization is often a neglected part of precision medicine. Many drugs are still being administered in "one dose fits all" regimens or based on parameters that are often only minor determinants for systemic exposure. These dosing approaches often introduce additional pharmacokinetic variability and do not add to treatment outcomes. Fortunately, pharmacological knowledge is increasing, providing valuable information regarding the potential of, for example, therapeutic drug monitoring. This article focuses on the evidence for the most promising and easily implemented optimized dosing approaches for the small-molecule inhibitors, chemotherapeutic agents, and monoclonal antibodies as treatment options currently approved for NSCLC. Despite limitations such as investigations having been conducted in oncological diseases other than NSCLC or the retrospective origin of many analyses, an alternative dosing regimen could be beneficial for treatment outcomes, prescriber convenience, or financial burden on healthcare systems. This review of the literature provides recommendations on the implementation of dose optimization and advice regarding promising strategies that deserve further research in NSCLC.

Evaluating the utility of therapeutic drug monitoring in the clinical use of small molecule kinase inhibitors: a review of the literature

Introduction: Orally administered small molecule kinase inhibitors (KI) are a key class of targeted anti-cancer medicines that have contributed substantially to improved survival outcomes in patients with advanced disease. Since the introduction of KIs in 2001, there has been a building body of evidence that the benefit derived from these drugs may be further enhanced by individualizing dosing on the basis of concentration.Areas covered: This review considers the rationale for individualized KI dosing and the requirements for robust therapeutic drug monitoring (TDM). Current evidence supporting TDM-guided KI dosing is presented and critically evaluated, and finally potential approaches to address translational challenges for TDM-guided KI dosing and alternate approaches to support individualization of KI dosing are discussed.Expert opinion: Intuitively, the individualization of KI dosing through an approach such as TDM-guided dosing has great potential to enhance the effectiveness and tolerability of these drugs. However, based on current literature evidence it is unrealistic to propose that TDM-guided KI dosing should be routinely implemented into clinical practice.

Monitoring of plasma concentrations of dabrafenib and trametinib in advanced BRAFV600mut melanoma patients

BACKGROUND

Dabrafenib (D) and trametinib (T) improved survival in patients with BRAFV600^mut melanoma. High plasma concentration of D (PCD) is weakly associated with adverse events (AE). We investigated the relationship between PCD/T and tumour control or AE.

METHODS

We analysed PCD/T in patients treated with D+T for metastatic melanoma. We collected data of tumour response (RECIST 1.1) and AE (CTCAE 4.0) blinded to PCD/T results.

RESULTS

We analysed 71 D and 58T assays from 34 patients. High inter-individual variability of PCD (median: 65.0ng/mL; interquartile range (IQR) [4-945]) and of PCT (median: 8.6ng/mL; IQR [5-39]) was observed. We found a weak relationship between PCD and progression-free survival, taking follow-up time into account (hazard ratio 0.991; 95%CI, 0.981 to 1.000; P=0.06). However, no difference was observed between mean PCD/T of progressing patients (n=21; 125±183ng/mL and 9.3±3.6ng/mL, respectively) and responders (complete, partial or stable response) (n=13; 159±225ng/mL, P=0.58 and 10.6±24.4ng/mL, P=0.29, respectively). No significant relationship was found between PCD/T and most common AEs (fever, lymphopenia, CPK increase, and hepatic cytolysis), body mass index, or age. Mean CPT (n=16) was significantly higher for female subjects (n=18; 11.5±4.8ng/mL) than for male subjects (8.8ng/mL±2.9, P=0.01), but no difference was observed between sex and CPD (P=0.32).

CONCLUSION

Our study showed a weak relationship between PCD and progression-free survival, but no relationship between PCD/T and AE was found. Monitoring PCD and PCT alone is unlikely to be useful in assessing response to treatment.

Dabrafenib and trametinib exposure-efficacy and tolerance in metastatic melanoma patients: a pharmacokinetic-pharmacodynamic real-life study

PURPOSE

Dabrafenib plus trametinib combination has greatly improved survival in BRAFV600^mut metastatic melanoma patients. However, data regarding the influence of pharmacokinetic markers in real-life patients are lacking. In this study, we aimed to explore dabrafenib and trametinib pharmacokinetic impact on progression-free survival (PFS), duration of response (DOR) or all grades treatment-related adverse events (ARAE) occurrence in routine care patients.

METHODS

BRAFV600^mut metastatic melanoma patients initiating standard doses of dabrafenib 150 mg BID plus trametinib 2 mg QD were included. Clinical data were collected via the French biobank MelBase, prospectively enrolling unresectable stage III or IV melanoma. Clinical response evaluation, ARAE reporting and dabrafenib and trametinib plasma quantification were performed. Association of individual Bayesian-estimated pharmacokinetic markers (AUC_0-τ and C_trough) and baseline clinical variables with DOR, PFS, clinical response, and ARAE was then assessed.

RESULTS

Fifty patients (comprising 4 AJCC stage IIIc and 46 stage IV) were included. Median PFS reached 11.4 months, and overall response rate 70%. Fifty percent of patients experienced ARAE (G3 n = 10, G4 n = 0). In univariate analysis, median dabrafenib C_trough within intermediate range was associated with a significantly higher PFS (HR [95% CI] = 0.41 [0.18; 0.91], p = 0.029) and DOR (HR [95% CI] = 0.39 [0.16; 0.94], p = 0.024), and association with DOR remained significant in multivariate analysis (HR [95% CI] = 0.34 [0.12; 0.95], p = 0.040). Trametinib pharmacokinetic markers were significantly higher in patients experiencing ARAE compared to patients without ARAE.

CONCLUSION

In this study, exposure-efficacy and tolerance analysis highlighted the interest of therapeutic drug monitoring to optimize therapeutic management in BRAFV600^mut metastatic melanoma patients based on trough concentrations of dabrafenib and trametinib.

Therapeutic drug monitoring of oral targeted antineoplastic drugs

PURPOSE

This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed.

METHODS

A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted.

RESULTS

OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy.

CONCLUSION

Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.

PD-L1 blockade in combination with inhibition of MAPK oncogenic signaling in patients with advanced melanoma

Combining PD-L1 blockade with inhibition of oncogenic mitogen-activated protein kinase (MAPK) signaling may result in long-lasting responses in patients with advanced melanoma. This phase 1, open-label, dose-escalation and -expansion study (NCT02027961) investigated safety, tolerability and preliminary efficacy of durvalumab (anti–PD-L1) combined with dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) for patients with BRAF-mutated melanoma (cohort A, n = 26), or durvalumab and trametinib given concomitantly (cohort B, n = 20) or sequentially (cohort C, n = 22) for patients with BRAF-wild type melanoma. Adverse events and treatment discontinuation rates were more common than previously reported for these agents given as monotherapy. Objective responses were observed in 69.2% (cohort A), 20.0% (cohort B) and 31.8% (cohort C) of patients, with evidence of improved tumor immune infiltration and durable responses in a subset of patients with available biopsy samples. In conclusion, combined MAPK inhibition and anti–PD-L1 therapy may provide treatment options for patients with advanced melanoma.

Immune checkpoints inhibitors or MAPK inhibitors are currently used as standard of care therapies for patients with advanced melanoma. Here the authors report a phase 1 clinical trial testing the anti-PD-L1 antibody durvalumab in combination with the BRAF inhibitor dafrafenib and the MEK inhibitor trametinib in patients with BRAFV600-mutant melanoma.

Development and validation of a sensitive liquid chromatography tandem mass spectrometry assay for the simultaneous determination of ten kinase inhibitors in human serum and plasma

A liquid chromatography tandem mass spectrometry method for the analysis of ten kinase inhibitors (afatinib, axitinib, bosutinib, cabozantinib, dabrafenib, lenvatinib, nilotinib, osimertinib, ruxolitinib, and trametinib) in human serum and plasma for the application in daily clinical routine has been developed and validated according to the US Food and Drug Administration and European Medicines Agency validation guidelines for bioanalytical methods. After protein precipitation of plasma samples with acetonitrile, chromatographic separation was performed at ambient temperature using a Waters XBridge® Phenyl 3.5 μm (2.1 × 50 mm) column. The mobile phases consisted of water-methanol (9:1, v/v) with 10 mM ammonium bicarbonate as phase A and methanol-water (9:1, v/v) with 10 mM ammonium bicarbonate as phase B. Gradient elution was applied at a flow rate of 400 μL/min. Analytes were detected and quantified using multiple reaction monitoring in electrospray ionization positive mode. Stable isotopically labeled compounds of each kinase inhibitor were used as internal standards. The acquisition time was 7.0 min per run. All analytes and internal standards eluted within 3.0 min. The calibration curves were linear over the range of 2–500 ng/mL for afatinib, axitinib, bosutinib, lenvatinib, ruxolitinib, and trametinib, and 6–1500 ng/mL for cabozantinib, dabrafenib, nilotinib, and osimertinib (coefficients of correlation ≥ 0.99). Validation assays for accuracy and precision, matrix effect, recovery, carryover, and stability were appropriate according to regulatory agencies. The rapid and sensitive assay ensures high throughput and was successfully applied to monitor concentrations of kinase inhibitors in patients.

Simultaneous quantification of dabrafenib, hydroxy-dabrafenib and trametinib in human plasma by liquid chromatography-tandem mass spectrometry

A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of dabrafenib (DAB), its main metabolite hydroxy-dabrafenib (OHD) and trametinib (TRA) in human plasma has been developed and validated. After addition of internal standard (dabrafenib-d9), extraction was achieved after protein precipitation with acetonitrile containing 1 % (v/v) formic acid. Chromatographic separation was performed on an Accucore® C18 (2.1 × 50 mm; 2.6 μm) column using a gradient elution of water acidified with 0.1 % (v/v) formic acid (A) and acetonitrile containing 0.1 % (v/v) formic acid (B) at a flow rate of 500 μL/min. The calibration ranged from 10 to 2000 ng/mL for DAB and OHD and from 5 to 50 ng/mL for TRA. This method was validated with satisfactory results including good precision (intra- and inter-assay coefficient of variation from 2.0 %-14.9 %) and good accuracy (inter- and intra-day bias between -1.2 % and 10.9 %), as well as long term stability in unprocessed plasma at -20 °C. This newly proposed method is useful for clinical research purposes as well as therapeutic drug monitoring for patients with a Rapidly Accelerated Fibrosarcoma kinase B (BRAF)-mutated cancer.

Population Pharmacokinetics/Pharmacodynamics of Dabrafenib Plus Trametinib in Patients with BRAF-Mutated Metastatic Melanoma

Patients treated with dabrafenib/trametinib (DAB/TRA) exhibit a large interindividual variability in clinical outcomes. The aims of this study were to characterize the pharmacokinetics of DAB, hydroxy-dabrafenib (OHD), and TRA in BRAF-mutated patients and to investigate the exposure–response relationship for toxicity and efficacy in metastatic melanoma (MM) patients. Univariate Fisher and Wilcoxon models including drug systemic exposure (area under the plasma concentration curve, AUC) were used to identify prognostic factors for the onset of dose-limiting toxicities (DLT), and Cox models for overall (OS) and progression-free survival (PFS). Seventy-three BRAF-mutated patients were included in pharmacokinetic (n = 424, NONMEM) and 52 in pharmacokinetic/pharmacodynamic analyses. Age and sex were identified as determinants of DAB and OHD clearances (p < 0.01). MM patients experiencing DLT were overexposed to DAB compared to patients without DLT (AUC: 9624 vs. 7485 ng∙h/mL, respectively, p < 0.01). Eastern Cooperative Oncology Group Performance Status (ECOG PS) ≥ 2 and plasma ratio AUC_OHD/AUC_DAB ≥ 1 were independently associated with shorter OS (HR: 6.58 (1.29–33.56); p = 0.023 and 10.61 (2.34–48.15), p = 0.022, respectively). A number of metastatic sites ≥3 and cerebral metastases were associated with shorter PFS (HR = 3.25 (1.11–9.50); p = 0.032 and HR = 1.23 (1.35–10.39), p = 0.011; respectively). TRA plasma exposure was neither associated with toxicity nor efficacy. Our results suggest that early drug monitoring could be helpful to prevent the onset of DLT in MM patients, especially in fragile patients such as the elderly. Regarding efficacy, the clinical benefit to monitor plasma ratio AUC_OHD/AUC_DAB deserves more investigation in a larger cohort of MM patients.

Pharmacokinetic Targets for Therapeutic Drug Monitoring of Small Molecule Kinase Inhibitors in Pediatric Oncology

In recent years new targeted small molecule kinase inhibitors have become available for pediatric patients with cancer. Relationships between drug exposure and treatment response have been established for several of these drugs in adults. Following these exposure-response relationships, pharmacokinetic (PK) target minimum plasma rug concentration at the end of a dosing interval (C_min ) values to guide therapeutic drug monitoring (TDM) in adults have been proposed. Despite the fact that variability in PK may be even larger in pediatric patients, TDM is only sparsely applied in pediatric oncology. Based on knowledge of the PK, mechanism of action, molecular driver, and pathophysiology of the disease, we bridge available data on the exposure-efficacy relationship from adults to children and propose target C_min values to guide TDM for the pediatric population. Dose adjustments in individual pediatric patients can be based on these targets. Nevertheless, further research should be performed to validate these targets.

A phase 2 study of trametinib for patients with pediatric glioma or plexiform neurofibroma with refractory tumor and activation of the MAPK/ERK pathway: TRAM-01

BACKGROUND

Pediatric low-grade gliomas (PLGG) are the most frequent brain tumors in children. Up to 50% will be refractory to conventional chemotherapy. It is now known that the majority of PLGG have activation of the MAPK/ERK pathway. The same pathway is also activated in plexiform neurofibromas (PNs) which are low-grade tumors involving peripheral nerves in patients with neurofibromatosis type 1 (NF1). These lesions are known to be refractory to chemotherapy. Specific MEK inhibitors such as trametinib are now available and have been approved for other cancers harboring mutations in the MAPK/ERK pathway such as melanoma. We have observed significant responses to trametinib in patients with refractory PLGG in our institutions and results from the phase I study are promising. The treatment appears not only efficacious but is also usually well tolerated. We hypothesize that we will observe responses in the majority of refractory PLGG and PN treated with trametinib in this phase 2 study.

METHODS

The primary objective is to determine the objective response rate of trametinib as a single agent for treatment of progressing/refractory tumors with MAPK/ERK pathway activation. The TRAM-01 study is a phase II multicentric open-label basket trial including four groups. Group 1 includes NF1 patients with progressing/refractory glioma. Group 2 includes NF1 patients with plexiform neurofibroma. Group 3 includes patients with progressing/refractory glioma with KIAA1549-BRAF fusion. Group 4 includes other patients with progressing/refractory glioma with activation of the MAPK/ERK pathway. Eligible patients for a given study group will receive daily oral trametinib at full dose for a total of 18 cycles of 28 days. A total of 150 patients will be enrolled in seven Canadian centers. Secondary objectives include the assessment of progression-free survival, overall survival, safety and tolerability of trametinib, serum levels of trametinib and evaluation of quality of life during treatment.

DISCUSSION

Trametinib will allow us to target directly and specifically the MAPK/ERK pathway. We expect to observe a significant response in most patients. Following our study, trametinib could be integrated into standard treatment of PLGG and PN.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03363217 December 6, 2017.

Individualized dosing of oral targeted therapies in oncology is crucial in the era of precision medicine

PURPOSE

While in the era of precision medicine, the right drug for each patient is selected based on molecular tumor characteristics, most novel oral targeted anticancer agents are still being administered using a one-size-fits-all fixed dosing approach. In this review, we discuss the scientific evidence for dose individualization of oral targeted therapies in oncology, based on therapeutic drug monitoring (TDM).

METHODS

Based on literature search and our own experiences, seven criteria for drugs to be suitable candidates for TDM will be addressed: (1) absence of an easily measurable biomarker for drug effect; (2) long-term therapy; (3) availability of a validated sensitive bioanalytical method; (4) significant variability in pharmacokinetic exposure; (5) narrow therapeutic range; (6) defined and consistent exposure-response relationships; (7) feasible dose-adaptation strategies.

RESULTS

All of these requirements are met for most oral targeted therapies in oncology. Also, prospective studies have already shown TDM to be feasible for imatinib, pazopanib, sunitinib, everolimus, and endoxifen.

CONCLUSIONS

In order to realize the full potential of personalized medicine in oncology, patients should not only be treated with the right drug, but also at the right dose. TDM could be a suitable tool to achieve this.

Identifying Candidate Druggable Targets in Canine Cancer Cell Lines Using Whole-Exome Sequencing

Cancer cell culture has been a backbone in cancer research, in which analysis of human cell line mutational profiles often correlates with oncogene addiction and drug sensitivity. We have conducted whole-exome sequence analyses on 33 canine cancer cell lines from 10 cancer types to identify somatic variants that contribute to pathogenesis and therapeutic sensitivity. A total of 66,344 somatic variants were identified. Mutational load ranged from 15.79 to 129.37 per Mb, and 13.2% of variants were located in protein-coding regions (PCR) of 5,085 genes. PCR somatic variants were identified in 232 genes listed in the Cancer Gene Census (COSMIC). Cross-referencing variants with human driving mutations on cBioPortal identified 61 variants as candidate cancer drivers in 30 cell lines. The most frequently mutated cancer driver was TP53 (15 mutations in 12 cell lines). No drivers were identified in three cell lines. We identified 501 non-COSMIC genes with PCR variants that functionally annotate with COSMIC genes. These genes frequently mapped to the KEGG MAPK and PI3K-AKT pathways. We evaluated the cell lines for ERK1/2 and AKT(S473) phosphorylation and sensitivity to the MEK1/2 inhibitor, trametinib. Twelve of the 33 cell lines were trametinib-sensitive (IC₅₀ < 32 nmol/L), all 12 exhibited constitutive or serum-activated ERK1/2 phosphorylation, and 8 carried MAPK pathway cancer driver variants: NF1(2), BRAF(3), N/KRAS(3). This functionally annotated database of canine cell line variants will inform hypothesis-driven preclinical research to support the use of companion animals in clinical trials to test novel combination therapies.

Therapeutic drug monitoring of small molecule kinase inhibitors in oncology in a real-world cohort study: does age matter?

AIM

Pharmacokinetics of small molecule kinase inhibitors (KIs) used in cancer treatment may alter with increasing age, but results are conflicting. This study aims to compare exposure to KIs between older and younger patients (≥70 and <70 years) in clinical practice.

METHODS

KI plasma concentrations of routinely treated patients were measured using validated assays. Calculated trough concentrations were compared in both age groups. For KIs with a clinically meaningful target concentration (erlotinib, imatinib, pazopanib, sunitinib and vemurafenib), influence of older age on target attainment was assessed.

RESULTS

We analysed 616 samples from 454 patients (median age: 61; range 20-93 years), treated with dabrafenib (n = 105), erlotinib (n = 49), imatinib (n = 165), pazopanib (n = 63), sunitinib (n = 87), trametinib (n = 95) and vemurafenib (n = 52). Older age did not significantly influence exposure to erlotinib, imatinib, pazopanib, sunitinib, trametinib and vemurafenib. Elderly patients had significantly higher dabrafenib trough concentrations than younger patients (P = 0.02; 62 ng ml^-1 (coefficient of variation [CV] 41%), vs. 53 ng ml^-1 (CV 46%), respectively). For KIs with a predefined target concentration, 68% of older and 61% of younger patients reached target.

CONCLUSIONS

In this real-world study, exposure to most included KIs was comparable in older and younger patients, except for dabrafenib, which showed higher exposure in older patients. In the absence of an absolute target for this KI, clinical relevance remains unclear. For all other included KIs, our data suggest no clinically relevant influence of older age on KI exposure.

Identification of Therapeutic Targets in Rhabdomyosarcoma through Integrated Genomic, Epigenomic, and Proteomic Analyses

Personalized cancer therapy targeting somatic mutations in patient tumors is increasingly being incorporated into practice. Other therapeutic vulnerabilities resulting from changes in gene expression due to tumor specific epigenetic perturbations are progressively being recognized. These genomic and epigenomic changes are ultimately manifest in the tumor proteome and phosphoproteome. We integrated transcriptomic, epigenomic, and proteomic/phosphoproteomic data to elucidate the cellular origins and therapeutic vulnerabilities of rhabdomyosarcoma (RMS). We discovered that alveolar RMS occurs further along the developmental program than embryonal RMS. We also identified deregulation of the RAS/MEK/ERK/CDK4/6, G2/M, and unfolded protein response pathways through our integrated analysis. Comprehensive preclinical testing revealed that targeting the WEE1 kinase in the G2/M pathway is the most effective approach in vivo for high-risk RMS.

Targeting MEK in a Translational Model of Histiocytic Sarcoma

Histiocytic sarcoma in humans is an aggressive orphan disease with a poor prognosis as treatment options are limited. Dogs are the only species that spontaneously develops histiocytic sarcoma with an appreciable frequency, and may have value as a translational model system. In the current study, high-throughput drug screening utilizing histiocytic sarcoma cells isolated from canine neoplasms identified these cells as particularly sensitive to a MEK inhibitor, trametinib. One of the canine cell lines carries a mutation in PTPN11 (E76K), and another one in KRAS (Q61H), which are associated with the activation of oncogenic MAPK signaling. Both mutations were previously reported in human histiocytic sarcoma. Trametinib inhibited sensitive cell lines by promoting cell apoptosis, indicated by a significant increase in caspase 3/7. Furthermore, in vitro findings were successfully recapitulated in an intrasplenic orthotopic xenograft mouse model, which represents a disseminated aggressive form of histiocytic sarcoma. Mice with histiocytic sarcoma xenograft neoplasms that were treated with trametinib had significantly longer survival times. Target engagement was validated as activity of ERK, downstream of MEK, was significantly downregulated in neoplasms of treated mice. Additionally, trametinib was found in plasma and neoplastic tissues within projected therapeutic levels. These findings demonstrate that in dogs, histiocytic sarcoma may be associated with a dysfunctional MAPK pathway, at least in some cases, and may be effectively targeted through MEK inhibition. Clinical trials to test safety and efficacy of trametinib in dogs with histiocytic sarcoma are warranted, and may provide valuable translational information to similar diseases in humans. Mol Cancer Ther; 17(11); 2439-50. ©2018 AACR.

Characterization of a conjunctival melanoma cell line CM-AS16, newly-established from a metastatic Han Chinese patient

Conjunctival melanoma (CM) is associated with metastases formation, can be fatal, and occurs in all different races. While cell lines are essential for experimental research, all available CM cell lines are derived from Caucasian patients. Furthermore, they are not derived from metastases. We aimed to establish a new CM cell line from a parotid metastasis in a Han Chinese patient and to depict its characteristics. The novel cell line, CM-AS16, was obtained from a surgical parotid sample and determined as a unique one with short tandem repeat (STR) analysis. It has been successively sub-cultured in vitro for more than 100 passages and exhibits rapid proliferation and migration. Chromosome analysis shows abundant chromosome aberrations, while whole exome sequencing (WES) reveals a typical NRAS mutation (Q61R). In vivo tumor growth was successfully established in a NOD/SCID mice model, and the immunophenotypes, such as HMB45, Melan A, S100, SOX10 and Ki67, manifested similar between the original tumor and the xenograft by immunohistochemistry. A MEK inhibitor binimetinib prominently suppressed in vitro cell growth by inhibiting ERK1/2 phosphorylation. In addition, monoclonal cells were used to demonstrate the drug sensitivity of different cells. In conclusion, the first cell line, CM-AS16, that is derived from a CM in a Han Chinese patient has highly malignant characteristics and a typical NRAS mutation. It may be used as a tool for further exploration of the molecular mechanisms of CM.

Development and validation of a liquid chromatography-tandem mass spectrometry analytical method for the therapeutic drug monitoring of eight novel anticancer drugs

To support therapeutic drug monitoring of patients with cancer, a fast and accurate method for simultaneous quantification of the registered anticancer drugs afatinib, axitinib, ceritinib, crizotinib, dabrafenib, enzalutamide, regorafenib and trametinib in human plasma using liquid chromatography tandem mass spectrometry was developed and validated. Human plasma samples were collected from treated patients and stored at -20°C. Analytes and internal standards (stable isotopically labeled analytes) were extracted with acetonitrile. An equal amount of 10 mm NH₄ CO₃ was added to the supernatant to yield the final extract. A 2 μL aliquot of this extract was injected onto a C₁₈ -column, gradient elution was applied and triple-quadrupole mass spectrometry in positive-ion mode was used for detection. All results were within the acceptance criteria of the latest US Food and Drug Administration guidance and European Medicines Agency guidelines on method validation, except for the carry-over of ceritinib and crizotinib. These were corrected for by the injection order of samples. Additional stability tests were carried out for axitinib and dabrafenib in relation to their reported photostability. In conclusion, the described method to simultaneously quantify the eight selected anticancer drugs in human plasma was successfully validated and applied for therapeutic drug monitoring in cancer patients treated with these drugs.

Practical Recommendations for Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Despite the fact that pharmacokinetic exposure of kinase inhibitors (KIs) is highly variable and clear relationships exist between exposure and treatment outcomes, fixed dosing is still standard practice. This review aims to summarize the available clinical pharmacokinetic and pharmacodynamic data into practical guidelines for individualized dosing of KIs through therapeutic drug monitoring (TDM). Additionally, we provide an overview of prospective TDM trials and discuss the future steps needed for further implementation of TDM of KIs.

Clinical Benefit from Trametinib in a Patient with Appendiceal Adenocarcinoma with a GNAS R201H Mutation

We report the case of a patient with appendiceal adenocarcinoma with mucinous peritoneal carcinomatosis who was treated with trametinib upon identification of a GNAS R201H mutation by comprehensive genomic profiling. The molecular pathology of appendiceal neoplasms is reviewed, and the mechanistic basis underlying the clinical benefit as well as the subsequent course on trametinib that were observed in this patient are discussed.

An UPLC-MS/MS method for the quantification of BRAF inhibitors (vemurafenib, dabrafenib) and MEK inhibitors (cobimetinib, trametinib, binimetinib) in human plasma. Application to treated melanoma patients

Targeted therapies for cancers are fast-growing therapies. For instance kinase inhibitors such as BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) are increasingly used to treat malignant melanoma. The metabolic profile of these drugs can result in great interindividual variability, justifying therapeutic drug monitoring (TDM). We describe a rapid and specific method for quantification of 2 BRAFi (vemurafenib, dabrafenib) and 3 MEKi (cobimetinib, trametinib and binimetinib). Chromatography was performed on a Waters Acquity-UPLC system with CORTECS C18+ column, under a gradient of 10% acetic acid in water/acetonitrile. An Acquity-TQD® with electrospray ionization was used for detection. Samples were prepared by solid phase extraction (Oasis® MCX microElution) before injection in the system. Calibration curves ranges from 0.4 to 100μg/ml for vemurafenib, from 1 to 1000ng/ml for dabrafenib, from 0.5 to 500ng/ml for cobimetinib and binimetinib, and from 0.75 to 250ng/ml for trametinib. At all concentrations the bias was within ±15% of the nominal concentrations and precision was ≤15%. All results were within the acceptance criteria of the EMA guidelines on method validation. This rapid, sensitive and specific UPLC-MS/MS method can perform simultaneous quantification of targeted therapies used in malignant melanoma and is usable for routine TDM.

Inventory of oral anticancer agents: Pharmaceutical formulation aspects with focus on the solid dispersion technique

Dissolution from the pharmaceutical formulation is a prerequisite for complete and consistent absorption of any orally administered drug, including anticancer agents (oncolytics). Poor dissolution of an oncolytic can result in low oral bioavailability, high variability in blood concentrations and with that suboptimal or even failing therapy. This review discusses pharmaceutical formulation aspects and absorption pharmacokinetics of currently licensed orally administered oncolytics. In nearly half of orally dosed oncolytics poor dissolution is likely to play a major role in low and unpredictable absorption. Dissolution-limited drug absorption can be improved with a solid dispersion which is a formulation method that induces super-saturated drug dissolution and with that it enhances in vivo absorption. This review discusses formulation principles with focus on the solid dispersion technology and how it works to enhance drug absorption. There are currently three licensed orally dosed oncolytics formulated as a solid dispersion (everolimus, vemurafenib and regorafenib) and these formulations result in remarkably improved dissolution and absorption compared to what can be achieved with conventional formulations of the respective oncolytics. Because of the successful implementation of these three solid dispersion formulations, we encourage the application of this formulation method for poorly soluble oral oncolytics.