Trametinib, a first-in-class oral MEK inhibitor mass balance study with limited enrollment of two male subjects with advanced cancers

Support Vector Machine-Based Prediction Models for Drug Repurposing and Designing Novel Drugs for Colorectal Cancer

Colorectal cancer (CRC) has witnessed a concerning increase in incidence and poses a significant therapeutic challenge due to its poor prognosis. There is a pressing demand to identify novel drug therapies to combat CRC. In this study, we addressed this need by utilizing the pharmacological profiles of anticancer drugs from the Genomics of Drug Sensitivity in Cancer (GDSC) database and developed QSAR models using the Support Vector Machine (SVM) algorithm for prediction of alternative and promiscuous anticancer compounds for CRC treatment. Our QSAR models demonstrated their robustness by achieving a high correlation of determination (R2) after 10-fold cross-validation. For 12 CRC cell lines, R2 ranged from 0.609 to 0.827. The highest performance was achieved for SW1417 and GP5d cell lines with R2 values of 0.827 and 0.786, respectively. Further, we listed the most common chemical descriptors in the drug profiles of the CRC cell lines and we also further reported the correlation of these descriptors with drug activity. The KRFP314 fingerprint was the predominantly occurring descriptor, with the KRFPC314 fingerprint following closely in prevalence within the drug profiles of the CRC cell lines. Beyond predictive modeling, we also confirmed the applicability of our developed QSAR models via in silico methods by conducting descriptor-drug analyses and recapitulating drug-to-oncogene relationships. We also identified two potential anti-CRC FDA-approved drugs, viomycin and diamorphine, using QSAR models. To ensure the easy accessibility and utility of our research findings, we have incorporated these models into a user-friendly prediction Web server named "ColoRecPred", available at https://project.iith.ac.in/cgntlab/colorecpred. We anticipate that this Web server can be used for screening of chemical libraries to identify potential anti-CRC drugs.

Colon Cancer Cells Evade Drug Action by Enhancing Drug Metabolism

Colorectal cancer (CRC) is the second most deadly cancer worldwide. One key reason is the failure of therapies that target RAS proteins, which represent approximately 40% of CRC cases. Despite the recent discovery of multiple alternative signalling pathways that contribute to resistance, durable therapies remain an unmet need. Here, we use liquid chromatography/mass spectrometry (LC/MS) analyses on Drosophila CRC tumour models to identify multiple metabolites in the glucuronidation pathway-a toxin clearance pathway-as upregulated in trametinib-resistant RAS/APC/P53 ("RAP") tumours compared to trametinib-sensitive RASG12V tumours. Elevating glucuronidation was sufficient to direct trametinib resistance in RASG12V animals while, conversely, inhibiting different steps along the glucuronidation pathway strongly reversed RAP resistance to trametinib. For example, blocking an initial HDAC1-mediated deacetylation step with the FDA-approved drug vorinostat strongly suppressed trametinib resistance in Drosophila RAP tumours. We provide functional evidence that pairing oncogenic RAS with hyperactive WNT activity strongly elevates PI3K/AKT/GLUT signalling, which in turn directs elevated glucose and subsequent glucuronidation. Finally, we show that this mechanism of trametinib resistance is conserved in an KRAS/APC/TP53 mouse CRC tumour organoid model. Our observations demonstrate a key mechanism by which oncogenic RAS/WNT activity promotes increased drug clearance in CRC. The majority of targeted therapies are glucuronidated, and our results provide a specific path towards abrogating this resistance in clinical trials.

Evaluation of a Low-Fat Low-Calorie Meal on the Relative Bioavailability of Trametinib and Dabrafenib: Results From a Randomized, Open-Label, 2-Part Study in Healthy Participants

In this randomized, open-label, 2-part, 2 × 2 crossover, phase 1 study, the effect of a low-fat low-calorie (LFLC) meal on the relative bioavailability of a trametinib 2-mg tablet or dabrafenib 150-mg capsule was evaluated in healthy participants. Trametinib adjusted geometric mean ratios (90%CI) of fed : fasted for area under the concentration-time curve (AUC) from time 0 to the last quantifiable concentration and AUC from time 0 extrapolated to infinity were 0.76 (0.71-0.82) and 0.82 (0.77-0.88), respectively. For dabrafenib, the adjusted geometric mean ratios of AUC from time 0 to the last quantifiable concentration and AUC from time 0 extrapolated to infinity (90%CI) for fed:fasted were 0.85 (0.79-0.91) and 0.86 (0.80-0.92), respectively. Consumption of an LFLC meal delayed trametinib and dabrafenib absorption, with an increase in time to maximum concentration of ≈15 and ≈30 minutes, respectively, compared to the fasted state. These findings indicate that consumption of an LFLC meal reduced the bioavailability and delayed the absorption of trametinib and dabrafenib, supporting current recommendations to administer both drugs in the fasting state; however, an occasional LFLC meal is unlikely to affect the pharmacokinetics of the drugs once steady state is reached and, by consequence, not likely to alter the overall intended efficacy.

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.

Comparative Bioavailability of a Single Dose of Trametinib (TMT212) Containing 9% vs 11% Dimethyl Sulfoxide in Randomized Healthy Volunteers to Assess Long-Term Storage at Room Temperature

Storage of trametinib tablets outside of 2-8°C protected from moisture may lead to loss of dimethyl sulfoxide (DMSO) and adversely impact trametinib bioavailability. In this open-label, phase 1, single-dose, randomized, 2-treatment, 2-period crossover study in healthy volunteers, bioavailability of a single 2-mg tablet of trametinib containing 9% DMSO (test formulation), corresponding to the lowest DMSO content in the tablet after storage at 25°C for 36 months, was evaluated vs bioavailability of a 2-mg tablet containing 11% DMSO (reference formulation). Sixty-five percent of subjects (n = 39/65) were men, and mean (standard deviation) age was 45.6 (11.17) years. Time to reach maximum plasma concentration occurred at 1.5 hours after dosing. The geometric mean ratio (90%CI) comparing 2-mg trametinib containing 9% DMSO with 2-mg trametinib containing 11% DMSO for area under the concentration-time curve from time 0 to the last measurable plasma concentration sampling time was 0.890 (0.848-0.935), suggesting the 2 formulations have similar bioavailability. The majority of adverse events were mild, with 1 subject experiencing 1 grade 3 headache. These results indicated that storage of trametinib at room temperatures ≤25°C during the overall shelf life of 36 months would not negatively impact trametinib bioavailability.

Pharmacokinetic Interaction Between the MEK1/MEK2 Inhibitor Trametinib and Oral Contraceptives Containing Norethindrone and Ethinyl Estradiol in Female Patients With Solid Tumors

This phase 1 postapproval study assessed the effect of the mitogen-activated protein kinase kinase enzyme 1/enzyme 2 inhibitor trametinib (2 mg once daily, repeat dosing) on the pharmacokinetics of combined oral contraceptives (COCs) containing norethindrone (NE; 1 mg daily) and ethinyl estradiol (EE; 0.035 mg daily) in 19 female patients with solid tumors. Compared with NE/EE administered without trametinib, NE/EE administered with steady-state trametinib was associated with a clinically nonrelevant 20% increase in NE exposure (area under the curve [AUC]) and no effect on EE exposure (geometric mean ratio [geo-mean] of NE/EE + trametinib to NE/EE [90%CI]: NE AUC calculated to the end of a dosing interval at steady-state [AUCtau ] 1.20 [1.02-1.41]; NE AUC from time zero to the last measurable concentration sampling time [AUClast ] 1.2 [0.999-1.45]; EE AUCtau 1.06 [0.923-1.22]; EE AUClast 1.05 [0.883-1.25]). Maximum serum concentration (Cmax ) of NE increased by 13% and Cmax of EE decreased by 8.5% when dosed with steady-state trametinib compared with COCs administered alone (geo-mean ratio [90%CI]: NE Cmax 1.13 [0.933-1.36]; EE Cmax 0.915 [0.803-1.04]). These results indicate that repeat-dose trametinib does not lower exposure to NE or EE and, hence, is unlikely to impact the contraceptive efficacy of COCs. The pharmacokinetic parameters of trametinib and its metabolite M5 were consistent with historic data of trametinib alone. Coadministration of trametinib and COCs was generally well tolerated in this study, with observed safety signals consistent with the known safety profile of trametinib and no new reported safety events. Overall, the findings indicate that hormonal COCs can be coadministered in female patients who receive trametinib monotherapy without compromising the contraceptive efficacy.

Tandem mass spectrometry of small-molecule signal transduction inhibitors: Accurate-m/z data to adapt structure proposals of product ions

Protein kinases inhibitors or, more generally, signal transduction inhibitors (STIs) can be used to treat diseases in which deregulation of the protein kinase activity plays a role, such as in cancer. A wide variety of drugs has been developed and/or is under investigation to act as protein kinase inhibitors, especially in tyrosine kinase inhibition. The bioanalysis of STIs has received considerable attention in the past 20 years. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) in selected-reaction monitoring (SRM) mode is the method-of-choice in such studies. In several of these studies from us and others, structures are proposed for the product ions applied in SRM. A critical review of these proposed structures is presented using accurate-m/z data, which we have now generated with a linear-ion-trap-Orbitrap hybrid mass spectrometer. This led to adaptation and new structural proposals of 18 product ions for 13 STIs. Our investigation endorses the power of accurate-m/z analysis in structure elucidation of product ions in bioanalytical LC-MS-MS studies and for which the SRM mode in tandem-quadrupole instruments is apparently less suitable.

Biliary Excretion-Mediated Food Effects and Prediction

Many orally administered drugs with negative food effects (i.e., lower exposure under fed conditions) are often primarily or partially eliminated by biliary excretion. The aim of this study is to assess the potential correlation between a negative food effect and biliary excretion. Correlation analysis was conducted using a training dataset containing 27 drugs which met the following criteria: (1) immediate-release formulations, (2) shows a negative food effect, (3) > 10% biliary clearance, and (4) does not undergo extensive metabolism. A correlation between fed-state biliary clearance (CL_b,fed) and fasted-state biliary clearance (CL_b,fast) (y = 1.81*x, R² = 0.68) was observed. The 1.8-fold increase in biliary clearance was then used as a correction factor to improve physiologically based pharmacokinetic (PBPK) prediction of food effects for 12 test drugs. The mean deviations of predicted fed/fasting AUC ratio and C_max ratio from clinically observed values were reduced from 32.4 to 17.2% and from 63.3 to 54.3%, respectively. In contrast to the positive food effects on most biopharmaceutics classification system (BCS) class II drugs for which food-stimulated bile flow increases drug solubility and absorption, our results suggest that the elimination of biliary excreted drugs is increased by food-stimulated bile flow, resulting in negative food effects.

Dabrafenib plus Trametinib: a Review in Advanced Melanoma with a BRAF (V600) Mutation

The BRAF inhibitor dabrafenib (Tafinlar(®)) and the MEK inhibitor trametinib (Mekinist(®)) are indicated, as monotherapy or in combination with each other, for the treatment of patients with unresectable or metastatic melanoma with a BRAF (V600) mutation. This article reviews the therapeutic efficacy and tolerability of combination treatment with dabrafenib and trametinib in this indication and summarizes relevant pharmacological data. Dabrafenib plus trametinib significantly prolonged progression-free survival (PFS) and overall survival (OS), improved objective response rates (ORRs) and preserved health-related quality of life (HR-QOL) to a greater extent than dabrafenib (in the double-blind COMBI-d study) and vemurafenib (in the open-label COMBI-v study) in two large, randomized, phase III studies in treatment-naïve patients with unresectable or metastatic melanoma with BRAF (V600E/K) mutation. Limited treatment benefit with the combination was also seen in patients who had progressed on prior BRAF inhibitor therapy, as indicated by ORRs of ≤ 15 % and stable disease in ≤ 50 % of patients in small phase I and II studies. Combination therapy did not increase overall toxicity relative to dabrafenib or vemurafenib monotherapy, with most adverse events (AEs) mild or moderate in severity and generally manageable. Fewer skin-related AEs (e.g. cutaneous malignancies, hyperkeratinosis and hand-foot syndrome) were reported with combination therapy than with dabrafenib or vemurafenib, probably because of reduced paradoxical activation of the MAPK pathway. Thus, dabrafenib plus trametinib provides an important treatment option for patients with BRAF (V600) mutation-positive unresectable or metastatic melanoma.

Pimasertib, a selective oral MEK1/2 inhibitor: absolute bioavailability, mass balance, elimination route, and metabolite profile in cancer patients

AIM

This trial (NCT: 01713036) investigated the absolute bioavailability, mass balance and metabolite profile of pimasertib in a new design combining these investigations in a single group of patients.

METHODS

Six male patients with pathologically confirmed, locally advanced or metastatic solid tumours were enrolled. Exclusion criteria included Eastern Cooperative Oncology Group performance status >1. In Part A of the trial, patients received a 60 mg oral dose of unlabelled pimasertib followed by an intravenous (i.v.) tracer dose of [¹⁴ C]pimasertib 2 μg (equalling 9 kBq) as a bolus injection, one hour after the oral dose, on Day 1. On Day 8, all patients received 60 mg pimasertib capsules spiked with 2.6 MBq of [¹⁴ C]pimasertib. Patients received 60 mg oral unlabelled pimasertib twice daily from Day 3 to Day 21 of Part A and in subsequent 21-day cycles in Part B.

RESULTS

Following i.v. administration, [¹⁴ C]pimasertib exhibited a geometric mean total body clearance of 45.7 l h^-1 (geometric coefficient of variation [geometric CV]: 47.2%) and a volume of distribution of 229 l (geometric CV: 42.0%). Absolute bioavailability was 73%. The majority of the oral [¹⁴ C] dose (85.1%) was recovered in excreta. Total radioactivity was mainly excreted into urine (52.8%) and faeces (30.7%) with 78.9% of the [¹⁴ C] dose recovered as metabolites. Two major circulating metabolites were identified in plasma: a carboxylic acid (M445) and a phosphoethanolamine conjugate (M554). The safety profile was in line with the published pimasertib trials.

CONCLUSION

Pimasertib showed a favourable pharmacokinetic profile with high absolute bioavailability and a unique metabolic pathway (conjugation with phosphoethanolamine).

Regulatory aspects of human radiolabeled mass balance studies in oncology: concise review

Human radiolabeled mass balance studies are performed to obtain information about the absorption, distribution, metabolism, and excretion of a drug in development. The main goals are to determine the route of elimination and major metabolic pathways. This review provides an overview of the current regulatory guidelines concerning human radiolabeled mass balance studies and discusses scientific trends seen in the last decade with a focus on mass balance studies of anticancer drugs. This paper also provides an overview of mass balance studies of anticancer agents that were executed in the last 10 years.

Safe handling of oral antineoplastic medications: Focus on targeted therapeutics in the home setting

Introduction With the growing number of oral targeted therapies being approved for use in cancer therapy, the potential for long-term administration of these drugs to cancer patients is expanding. The use of these drugs in the home setting has the potential to expose family members and caregivers to them either through direct contact with the drugs or indirectly by exposure to the parent compounds and/or their active metabolites in contaminated patients' waste. Methods A systematic literature review was performed and the known adverse health effect of 32 oral targeted therapeutics is summarized. In particular, the carcinogenicity, genotoxicity, and embryo-fetal toxicity, along with the route of excretion were evaluated. Results Carcinogenicity testing has not been performed on most of the oral targeted therapeutics and the genotoxicity data are mixed. However, the majority of these drugs exhibit adverse reproductive effects, some of which are severe. Currently, available data does not permit the possibility of a health hazard from inappropriate handling of drugs and contaminated patients waste to be ignored, especially in a long-term home setting. Further research is needed to understand these issues. Conclusions With the expanding use of targeted therapies in the home setting, family members and caregivers, especially those of reproductive risk age, are, potentially at risk. Overall basic education and related precautions should be taken to protect family members and caregivers from indirect or direct exposure from these drugs. Further investigations and discussion on this subject are warranted.

Human absorption, distribution, metabolism and excretion properties of drug molecules: a plethora of approaches

Human radiolabel studies are traditionally conducted to provide a definitive understanding of the human absorption, distribution, metabolism and excretion (ADME) properties of a drug. However, advances in technology over the past decade have allowed alternative methods to be employed to obtain both clinical ADME and pharmacokinetic (PK) information. These include microdose and microtracer approaches using accelerator mass spectrometry, and the identification and quantification of metabolites in samples from classical human PK studies using technologies suitable for non-radiolabelled drug molecules, namely liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. These recently developed approaches are described here together with relevant examples primarily from experiences gained in support of drug development projects at GlaxoSmithKline. The advantages of these study designs together with their limitations are described. We also discuss special considerations which should be made for a successful outcome to these new approaches and also to the more traditional human radiolabel study in order to maximize knowledge around the human ADME properties of drug molecules.

Concomitant oral and intravenous pharmacokinetics of trametinib, a MEK inhibitor, in subjects with solid tumours

AIMS

The aim of this phase 1, single centre, open label study in four patients with solid tumours was to determine the absolute bioavailability of a 2 mg oral dose of trametinib. Trametinib is an orally bioavailable, reversible and selective allosteric inhibitor of MEK1 and MEK2 activation and kinase activity.

METHODS

A microtracer study approach, in which a 5 μg radiolabelled i.v. microdose of trametinib was given concomitantly with an unlabelled 2 mg oral tablet formulation, was used to recover i.v. and oral pharmacokinetic parameters, simultaneously.

RESULTS

The least-squares mean (90% confidence interval) absolute bioavailability of trametinib (2 mg tablet) was 72.3% (50.0%, 104.6%). Median tmax after oral administration was 1.5 h and the geometric mean terminal half-life was 11 days. The geometric mean clearance and volume of distribution after i.v. administration were 3.21 l h(-1) and 976 l, respectively, resulting in a terminal elimination half-life of 11 days.

CONCLUSIONS

Trametinib absolute bioavailability was moderate to high, whereas first pass metabolism was low.

Targeted biopharmaceuticals for cancer treatment

Cancer is a complex invasive genetic disease that causes significant mortality rate worldwide. Protein-based biopharmaceuticals have significantly extended the lives of millions of cancer patients. This article reviews the biological function and application of targeted anticancer biopharmaceuticals. We first discuss the specific antigens and core pathways that are used in the development of targeted cancer therapy. The innovative monoclonal antibodies, non-antibody proteins, and small molecules targeting these antigens or pathways are then reviewed. Finally, the current challenges in anticancer biopharmaceuticals development and the potential solutions to address these challenges are discussed.