Clinical Pharmacokinetics of the Androgen Receptor Inhibitor Darolutamide in Healthy Subjects and Patients with Hepatic or Renal Impairment.

BACKGROUND: Darolutamide is a second-generation androgen receptor inhibitor approved for the treatment of nonmetastatic castration-resistant prostate cancer at a dosage of 600 mg orally twice daily. OBJECTIVE: We aimed to fully characterize the pharmacokinetic profile of darolutamide, its diastereomers, and its main active metabolite, keto-darolutamide. METHODS: Single-dose and multiple-dose pharmacokinetics of 14C-labeled and non-labeled darolutamide were evaluated in healthy subjects and patients with hepatic or renal impairment. RESULTS: Following darolutamide oral tablet administration, peak plasma concentrations were reached 4-6 h after dosing. Darolutamide elimination was characterized by a half-life of 13 h. Steady state was reached after approximately 2 days of twice-daily dosing. Pharmacokinetics of the diastereomers and keto-darolutamide followed similar trends to the parent compound. Darolutamide absorption from the tablet was lower than from the oral solution; tablet absolute bioavailability was ~30% in the fasted state but improved to 60-75% when given with food. The unbound fraction of darolutamide in plasma was 7.8%. The administered 1:1 ratio of the diastereomers (S,R)-darolutamide and (S,S)-darolutamide changed to ~1:6 in plasma following multiple dosing. Similar exposure and diastereomer ratios after single and multiple dosing indicate time-independent (no autoinduction) linear pharmacokinetics. Darolutamide exposure increased in patients with moderate hepatic or severe renal impairment vs healthy subjects; dose adaptation at treatment initiation should be considered in these patients. CONCLUSIONS: Darolutamide 600 mg twice daily demonstrates predictable linear pharmacokinetics and sustainably high plasma concentrations, suggesting the potential for constant inhibition of the androgen receptor signaling pathway. CLINICAL TRIALS REGISTRATION: NCT02418650, NCT02894385, NCT02671097.

First-in-Human Trial of the Oral Ataxia Telangiectasia and RAD3-Related (ATR) Inhibitor BAY 1895344 in Patients with Advanced Solid Tumors.

Targeting the ataxia telangiectasia and RAD3-related (ATR) enzyme represents a promising anticancer strategy for tumors with DNA damage response (DDR) defects and replication stress, including inactivation of ataxia telangiectasia mutated (ATM) signaling. We report the dose-escalation portion of the phase I first-in-human trial of oral ATR inhibitor BAY 1895344 intermittently dosed 5 to 80 mg twice daily in 21 patients with advanced solid tumors. The MTD was 40 mg twice daily 3 days on/4 days off. Most common adverse events were manageable and reversible hematologic toxicities. Partial responses were achieved in 4 patients and stable disease in 8 patients. Median duration of response was 315.5 days. Responders had ATM protein loss and/or deleterious ATM mutations and received doses ≥40 mg twice daily. Overall, BAY 1895344 is well tolerated, with antitumor activity against cancers with certain DDR defects, including ATM loss. An expansion phase continues in patients with DDR deficiency. SIGNIFICANCE: Oral BAY 1895344 was tolerable, with antitumor activity in heavily pretreated patients with various advanced solid tumors, particularly those with ATM deleterious mutations and/or loss of ATM protein; pharmacodynamic results supported a mechanism of action of increased DNA damage. Further study is warranted in this patient population.See related commentary by Italiano, p. 14.This article is highlighted in the In This Issue feature, p. 1.

Safety and efficacy of BAY1436032 in IDH1-mutant AML: phase I study results.

The mutant IDH1 (mIDH1) inhibitor BAY1436032 demonstrated robust activity in preclinical AML models, supporting clinical evaluation. In the current dose-escalation study, BAY1436032 was orally administered to 27 mIDH1 AML subjects across 4 doses ranging from 300 to 1500 mg twice-daily. BAY1436032 exhibited a relatively short half-life and apparent non-linear pharmacokinetics after continuous dosing. Most subjects experienced only partial target inhibition as indicated by plasma R-2HG levels. BAY1436032 was safe and a maximum tolerated dose was not identified. The median treatment duration for all subjects was 3.0 months (0.49-8.5). The overall response rate was 15% (4/27; 1 CRp, 1 PR, 2 MLFS), with responding subjects experiencing a median treatment duration of 6.0 months (3.9-8.5) and robust R-2HG decreases. Thirty percent (8/27) achieved SD, with a median treatment duration of 5.5 months (3.1-7.0). Degree of R-2HG inhibition and clinical benefit did not correlate with dose. Although BAY1436032 was safe and modestly effective as monotherapy, the low overall response rate and incomplete target inhibition achieved at even the highest dose tested do not support further clinical development of this investigational agent in AML.

Phase 1 Dose Escalation Study of the Allosteric AKT Inhibitor BAY 1125976 in Advanced Solid Cancer-Lack of Association between Activating AKT Mutation and AKT Inhibition-Derived Efficacy.

This open-label, phase I first-in-human study (NCT01915576) of BAY 1125976, a highly specific and potent allosteric inhibitor of AKT1/2, aimed to evaluate the safety, pharmacokinetics, and maximum tolerated dose of BAY 1125976 in patients with advanced solid tumors. Oral dose escalation was investigated with a continuous once daily (QD) treatment (21 days/cycle) and a twice daily (BID) schedule. A dose expansion in 28 patients with hormone receptor-positive metastatic breast cancer, including nine patients harboring the AKT1E17K mutation, was performed at the recommended phase 2 dose (R2D) of 60 mg BID. Dose-limiting toxicities (Grades 3-4) were increased in transaminases, γ-glutamyltransferase (γ-GT), and alkaline phosphatase in four patients in both schedules and stomach pain in one patient. Of the 78 patients enrolled, one patient had a partial response, 30 had stable disease, and 38 had progressive disease. The clinical benefit rate was 27.9% among 43 patients treated at the R2D. AKT1E17K mutation status was not associated with tumor response. Genetic analyses revealed additional mutations that could promote tumor cell growth despite the inhibition of AKT1/2. BAY 1125976 was well tolerated and inhibited AKT1/2 signaling but did not lead to radiologic or clinical tumor responses. Thus, the refinement of a selection of biomarkers for AKT inhibitors is needed to improve their monotherapy activity.

Drug-Drug Interaction Potential of Darolutamide: In Vitro and Clinical Studies.

BACKGROUND AND OBJECTIVES: Darolutamide is a novel androgen receptor (AR) antagonist approved for the treatment of nonmetastatic castration-resistant prostate cancer (nmCRPC). Accordingly, the drug-drug interaction (DDI) potential of darolutamide was investigated in both nonclinical and clinical studies. METHODS: In vitro studies were performed to determine the potential for darolutamide to be a substrate, inducer or inhibitor for cytochrome P450 (CYP) isoforms, other metabolizing enzymes and drug transporters. A phase I drug-interaction study in healthy volunteers evaluated the impact of co-administering rifampicin [CYP3A4 and P-glycoprotein (P-gp) inducer] and itraconazole [CYP3A4, P-gp and breast cancer resistance protein (BCRP) inhibitor] on the pharmacokinetics of darolutamide. Two further phase I studies assessed the impact of co-administering oral darolutamide on the pharmacokinetics of midazolam (sensitive CYP3A4 substrate) and dabigatran etexilate (P-gp substrate) and the impact on the pharmacokinetics of co-administered rosuvastatin [a substrate for BCRP, organic anion-transporting polypeptide (OATP)1B1, OATP1B3 and organic anion transporter (OAT)3]. RESULTS: In vitro, darolutamide was predominantly metabolized via oxidative biotransformation catalyzed by CYP3A4 and was identified as a substrate for P-gp and BCRP. The enzymatic activity of nine CYP isoforms was not inhibited or slightly inhibited in vitro with darolutamide, and a rank order and mechanistic static assessment indicated that risk of clinically relevant DDIs via CYP inhibition is very low. In vitro, darolutamide exhibited no relevant induction of CYP1A2 or CYP2B6 activity. Inhibition of BCRP-, P-gp-, OAT3-, MATE1-, MATE2-K-, OATP1B1- and OATP1B3-mediated transport was observed in vitro. Phase I data showed that darolutamide exposure increased 1.75-fold with co-administered itraconazole and decreased by 72% with rifampicin. Co-administration of darolutamide with CYP3A4/P-gp substrates showed no effect or only minor effects. Rosuvastatin exposure increased 5.2-fold with darolutamide because of BCRP and probably also OATPB1/OATPB3 inhibition. CONCLUSIONS: Darolutamide has a low potential for clinically relevant DDIs with drugs that are substrates for CYP or P-gp; increased exposure of BCRP and probably OATP substrates was the main interaction of note.

First-in-human phase I study of the bromodomain and extraterminal motif inhibitor BAY 1238097: emerging pharmacokinetic/pharmacodynamic relationship and early termination due to unexpected toxicity.

BACKGROUND: Bromodomain and extraterminal motif (BET) protein inhibition is a promising cancer treatment strategy, notably for targeting MYC- or BRD4-driven diseases. A first-in-human study investigated the safety, pharmacokinetics, maximum tolerated dose and recommended phase II dose of the BET inhibitor BAY 1238097 in patients with advanced malignancies. MATERIAL AND METHODS: In this phase I, open-label, non-randomised, multicentre study, patients with cytologically or histologically confirmed advanced refractory malignancies received oral BAY 1238097 twice weekly in 21-day cycles using an adaptive dose-escalation design at a starting dose of 10 mg/week. Model-based dose-response analysis was performed to guide dose escalation. Safety, pharmacokinetics, pharmacodynamics and tumour response were evaluated. RESULTS: Eight patients were enrolled at three dose levels (10 mg/week, n = 3; 40 mg/week, n = 3; 80 mg/week, n = 2). Both patients receiving 80 mg/week had dose-limiting toxicities (DLTs) (grade 3 vomiting, grade 3 headache and grade 2/3 back pain). The most common adverse events were nausea, vomiting, headache, back pain and fatigue. Pharmacokinetic analysis indicated a linear dose response with increasing dose. Two patients displayed prolonged stable disease; no responses were observed. Biomarker evaluation of MYC and HEXIM1 expression demonstrated an emerging pharmacokinetic/pharmacodynamic relationship, with a trend towards decreased MYC and increased HEXIM1 expression in response to treatment. CONCLUSION: The study was prematurely terminated because of the occurrence of DLTs at a dose below targeted drug exposure. Pharmacokinetic modelling indicated that an alternate dosing schedule whereby DLTs could be avoided while reaching efficacious exposure was not feasible. Registration number: NCT02369029.

Discovery and Characterization of AZD6738, a Potent Inhibitor of Ataxia Telangiectasia Mutated and Rad3 Related (ATR) Kinase with Application as an Anticancer Agent.

The kinase ataxia telangiectasia mutated and rad3 related (ATR) is a key regulator of the DNA-damage response and the apical kinase which orchestrates the cellular processes that repair stalled replication forks (replication stress) and associated DNA double-strand breaks. Inhibition of repair pathways mediated by ATR in a context where alternative pathways are less active is expected to aid clinical response by increasing replication stress. Here we describe the development of the clinical candidate 2 (AZD6738), a potent and selective sulfoximine morpholinopyrimidine ATR inhibitor with excellent preclinical physicochemical and pharmacokinetic (PK) characteristics. Compound 2 was developed improving aqueous solubility and eliminating CYP3A4 time-dependent inhibition starting from the earlier described inhibitor 1 (AZ20). The clinical candidate 2 has favorable human PK suitable for once or twice daily dosing and achieves biologically effective exposure at moderate doses. Compound 2 is currently being tested in multiple phase I/II trials as an anticancer agent.

Preliminary pharmacokinetic and bioanalytical studies of SJG-136 (NSC 694501), a sequence-selective pyrrolobenzodiazepine dimer DNA-cross-linking agent.

SJG-136 is a synthetic pyrrolobenzodiazepine (PBD) dimer in which two DNA-alkylating subunits are linked through an inert propanedioxy tether. Biophysical and biochemical studies of SJG-136 have shown a remarkable affinity for DNA and potent cytotoxicity in vitro. On this basis, together with its unique sequence selectivity and interstrand DNA cross-linking activity, SJG-136 has been selected for clinical trials. This study examines the pharmacological characteristics of SJG-136 and provides the first report of pharmacokinetic properties for this agent. A sensitive, selective and reproducible reversed-phase gradient LC/MS assay has been developed for detection and analysis, where a molecular ion ( m / z 557.2) is detectable for the SJG-136 parent imine. Fluorescence detection (260 nm excitation, 420 nm emission) gives a limit of sensitivity of 5 nM (2.5 ng ml(-1)) for analysis of SJG-136 in mouse plasma. Extraction efficiencies from plasma were >65% across a range of concentrations (5-1000 nM). Following administration to mice at the MTD (i.p., 0.2 mg kg(-1)), high peak plasma concentrations of SJG-136 were seen ( C (max) = 336 nM) at 30 min after dosing. A calculated terminal t (1/2) of 0.98 h and AUC of 0.34 microM.h resulted in a clearance rate of 17.7 ml min(-1) kg(-1). The PBD dimer binds only moderately to proteins (65-75%), and in vitro cytotoxicity studies confirmed IC(50) values of 4-30 nM with a panel of human cell lines. This finding demonstrates that plasma concentrations achieved in the mouse are substantially higher than those required to elicit an anti tumour response in vitro. This report forms an important phase in the pre-clinical characterization of the compound.