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The biotransformation and excretion of darolutamide were investigated in a phase I study. Six healthy male volunteers received a single dose of 300 mg 14C-darolutamide as an oral solution in the fasted state. Plasma, urine, and feces samples were analyzed for mass balance evaluation by liquid scintillation counting (LSC). Metabolite profiling and identification were determined using liquid chromatography mass-spectrometry with off-line radioactivity detection using LSC. Complete mass balance was achieved, with mean radioactivity recovery of 95.9% within 168 hours (63.4% in urine, 32.4% in feces). The administered 1:1 ratio of (S,R)- and (S,S)-darolutamide changed to approximately 1:5, respectively, in plasma. Darolutamide and the oxidation product, keto-darolutamide, were the only components quantifiable by LSC in plasma, accounting for 87.4% of total radioactivity, with a 2.1-fold higher plasma exposure for keto-darolutamide. Aside from darolutamide, the most prominent metabolites in urine were O-glucoronide (M-7a/b) and N-glucuronide (M-15a/b), as well as pyrazole sulfates (M-29, M-24) and glucuronides (M-21, M-22) resulting from oxidative cleavage of the parent. The darolutamide diastereomers were mainly detected in feces. In vitro assays showed that darolutamide metabolism involves a complex interplay between oxidation and reduction, as well as glucuronidation. Interconversion of the diastereomers involves oxidation to keto-darolutamide, primarily mediated by CYP3A4, followed by reduction predominantly catalyzed by cytosolic reductase(s), with aldo-keto reductase 1C3 playing the major role. The latter reaction showed stereoselectivity with preferential formation of (S,S)-darolutamide. SIGNIFICANCE STATEMENT: The metabolism and excretion of darolutamide in humans revealed that oxidation (CYP3A4) and glucuronidation (UGT1A9, UGT1A1) were the main metabolic routes of elimination. Direct excretion also contributed to overall clearance. The two pharmacologically equipotent diastereomers of darolutamide interconvert primarily via oxidation to the active metabolite keto-darolutamide, followed by reduction predominantly by cytosolic reductase(s). The latter reaction showed stereoselectivity with preferential formation of (S,S)-darolutamide. Data indicate a low drug-drug interaction potential of darolutamide with inducers or inhibitors of metabolizing enzymes.

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. Electronic supplementary material The online version of this article (10.1007/s13318-019-00577-5) contains supplementary material, which is available to authorized users.

Background: Saini et al. recently investigated the pharmacokinetics of darolutamide and its diastereomers in vitro and in vivo in Balb/c mice, reporting higher levels of (S,S)-darolutamide than (S,R)-darolutamide following intravenous or oral dosing, and interconversion of (S,R)-darolutamide to (S,S)-darolutamide. Objective: To present our in vitro and in vivo studies of darolutamide pharmacokinetics in mice, which contrast with the findings of Saini et al. Methods: Nude male Balb/c mice were orally dosed for 7 days with 25, 50, or 100 mg/kg of darolutamide twice daily. Pharmacokinetic parameters in plasma and tissue samples were assessed by liquid chromatography-tandem mass spectrometry. Metabolism and interconversion of darolutamide and its diastereomers were investigated in cryopreserved Balb/c mouse hepatocytes. Protein binding was determined in plasma samples by equilibrium dialysis. Results : On day 7, Cmaxwas reached 30 min after the last dose. Rapid formation and greater exposure of keto-darolutamide versus darolutamide were observed. Plasma exposure of (S,R)-darolutamide was 3-5-fold higher than that of (S,S)-darolutamide. The fraction of unbound keto-darolutamide was almost 6-fold lower than for darolutamide. Conclusion: The darolutamide diastereomer ratio changes upon administration in mice and other species due to interconversion through keto-darolutamide. This is not considered clinically relevant since both diastereomers and keto- darolutamide are pharmacologically similar in vitro. Based on the high protein binding of keto-darolutamide, its contribution in vivo in humans is considered low.

1. Darolutamide is a novel selective androgen receptor antagonist consisting of two pharmacologically equipotent diastereoisomers. The absorption, distribution, metabolism and excretion properties of darolutamide in rats are reported.2. Non- or [

Background Darolutamide, an androgen receptor antagonist with a distinct molecular structure, significantly prolonged metastasis-free survival versus placebo in the phase III ARAMIS study in men with nonmetastatic castration-resistant prostate cancer (nmCRPC). In this population, polypharmacy for age-related comorbidities is common and may increase drug–drug interaction (DDI) risks. Preclinical/phase I study data suggest darolutamide has a low DDI potential—other than breast cancer resistance protein/organic anion transporter protein substrates (e.g., statins), no clinically relevant effect on comedications is expected. Objective Our objective was to evaluate the effect of commonly administered drugs on the pharmacokinetics of darolutamide and the effect of comedications potentially affected by darolutamide on safety in patients with nmCRPC. Patients and Methods Comorbidities and comedication use in the 1509 ARAMIS participants treated with darolutamide 600 mg twice daily or placebo were assessed. A population pharmacokinetic analysis evaluated whether comedications affected the pharmacokinetics of darolutamide in a subset of 388 patients. A subgroup analysis of adverse events (AEs) in statin users versus nonusers was conducted. Results Most participants (median age 74 years) had at least one comorbidity (98.4% in both arms) and used at least one comedication (98.7% with darolutamide vs. 98.0% with placebo); these were similar across study arms. Despite frequent use of comedications with DDI potential, no significant effects on darolutamide pharmacokinetics were identified. Comedications included lipid-modifying agents (34.5%), β-blockers (29.7%), antithrombotics (42.8%), and systemic antibiotics (26.9%). AE incidence was similar across study arms in statin users and nonusers. Study limitations include the small sample size for sub-analyses. Conclusions These analyses suggest the pharmacokinetic profile of darolutamide is not affected by a number of commonly administered drugs in patients with nmCRPC. Although pharmacokinetic data have indicated that darolutamide has the potential to interact with rosuvastatin, used to assess DDI in these studies, this finding did not seem to translate into increased AEs due to statin use in the ARAMIS trial. Clinicaltrials.gov identifier: NCT02200614. Electronic supplementary material The online version of this article (10.1007/s11523-019-00674-0) contains supplementary material, which is available to authorized users., Plain Language Summary Background Darolutamide is a medicine used to treat men with prostate cancer that has not spread to other parts of the body (nonmetastatic). Often, these patients are taking other medicines for common age-related illnesses. Taking more than one medicine at the same time increases the chances of what is known as drug–drug interactions. Drug–drug interactions can decrease how well the medicines work or may sometimes increase side effects. Study Aim To test for possible drug–drug interactions in men with prostate cancer who take darolutamide alongside other medicines. Study Participants Men with nonmetastatic prostate cancer who were being treated with a medicine that lowers testosterone, a chemical in the body that causes prostate cancer tumors to grow. Participants took two darolutamide 300 mg tablets, or an inactive placebo, twice a day. What Did the Researchers Measure? The researchers documented the number of medicines taken by each participant and the number of other medical conditions that they had. Tests were done to find out whether other medicines affected the way that darolutamide works in the body and whether patients taking darolutamide alongside other medicines experienced more side effects. Results As would be expected, based on the typical age of patients with prostate cancer, more than 90% of participants in this study used medicines other than darolutamide to manage common age-related illnesses or medical conditions. Taking medicines alongside darolutamide did not impact how darolutamide worked in the body and did not increase the number of side effects experienced by patients. Darolutamide is known to interact with rosuvastatin, a cholesterol-lowering drug. However, in this study, there was no overall increase in side effects among darolutamide-treated patients who took this type of drug compared with in those who did not. Conclusion In this study of patients with nonmetastatic prostate cancer, limited drug–drug interactions were seen when taking darolutamide alongside other medicines given to these patients to manage age-related medical conditions. Electronic supplementary material The online version of this article (10.1007/s11523-019-00674-0) contains supplementary material, which is available to authorized users.

Background DARO is an androgen receptor antagonist with a distinct molecular structure, which has demonstrated prolonged metastasis-free survival vs placebo (PBO) in the phase 3 ARAMIS study in non-metastatic castration-resistant prostate cancer patients. These typically older patients often receive multiple comedications. We assessed DDIs with DARO both in vitro and in clinical trial development. Methods The effects of induction and inhibition of transporters and CYP enzymes on DARO, and the effect of DARO on other comedications were studied in vitro and in several phase 1 trials using rifampicin (CYP3A4, P-gp inducer), itraconazole (ICZ; CYP3A4, P-gp inhibitor), rosuvastatin (BCRP, OATP1B1, OATP1B3 and OAT3 substrate), midazolam (CYP3A4 substrate) and dabigatran etexilate (P-gp substrate). The impact of comedication on DARO was investigated in a population pharmacokinetic (popPK) and covariate analysis of a subset of ARAMIS patients. The adverse event (AE) profile for comedication use between PBO and DARO was also analysed. Results Concomitant rifampicin led to a 3.5-fold decrease in DARO area under the curve (AUC) vs DARO alone. ICZ resulted in 1.8-fold increase in DARO AUC vs DARO alone. No significant effect of comedications that are CYP or P-gp inhibitors was identified in the popPK analysis; proton pump inhibitors did not significantly affect the PK of DARO. Effects of DARO on CYP inhibition in vitro were negligible and coadministration of midazolam or dabigatran showed no clinically relevant effects. Rosuvastatin AUC increased by 5.2-fold with DARO vs rosuvastatin alone, attributed mainly to BCRP inhibition. The incidence of AEs in ARAMIS was low; comedication use (98.7% in DARO, 98.0% in PBO arms) and AE profile were similar between study arms. Conclusions DDIs with DARO and P-gp or CYP enzyme substrates, e.g. antithrombotics, calcium channel blockers or proton pump inhibitors, are not expected. Strong CYP3A4 inducers, e.g. rifampicin and carbamazepine, showed some interaction with DARO. Effects of CYP3A4 or P-gp inhibitors on DARO were not considered clinically relevant. DARO may increase the exposure of concomitant BCRP substrates, e.g. statins, although a safety and AE analysis from ARAMIS did not indicate any relevant impact of DARO. Clinical trial identification NCT03237416, NCT03048110, NCT02671097, NCT02200614. Editorial acknowledgement Medical writing support: Lucy Smithers, PhD, and editorial support: Beth King, both of Scion Medica, London, supported by Bayer according to Good Publication Practice guidelines. Legal entity responsible for the study Bayer. Funding Bayer and Orion Corporation. Disclosure C.R. Zurth: Full / Part-time employment: Bayer. K. Fizazi: Honoraria (self), Advisory / Consultancy: Merck, Sharp & Dohme; Advisory / Consultancy: Bayer; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Janssen; Advisory / Consultancy: AstraZeneca; Honoraria (self), Advisory / Consultancy: Sanofi; Honoraria (self), Advisory / Consultancy: Astellas; Advisory / Consultancy: Orion; Advisory / Consultancy: CureVac; Advisory / Consultancy: Clovis. R. Fricke: Full / Part-time employment: Bayer. H. Gieschen: Full / Part-time employment: Bayer. K. Graudenz: Full / Part-time employment: Bayer. M. Koskinen: Full / Part-time employment: Orion Corporation. B.A. Ploeger: Full / Part-time employment: Bayer. O. Prien: Shareholder / Stockholder / Stock options, Full / Part-time employment: Bayer. M.R. Smith: Advisory / Consultancy: Bayer; Advisory / Consultancy: Amgen; Advisory / Consultancy: Astellas; Advisory / Consultancy: Clovis; Advisory / Consultancy: Gilead; Honoraria (self): Hinova; Honoraria (self), Advisory / Consultancy: Janssen; Honoraria (self), Advisory / Consultancy: Eli Lilly; Honoraria (self), Advisory / Consultancy: Novartis; Honoraria (self), Advisory / Consultancy: Pfizer. T. Tammela: Honoraria (self), Research grant / Funding (institution): Bayer; Advisory / Consultancy: Janssen; Advisory / Consultancy, Research grant / Funding (institution): Lidds AB; Advisory / Consultancy, Research grant / Funding (institution): Astellas. N.D. Shore: Advisory / Consultancy, Research grant / Funding (self): Ferring; Advisory / Consultancy, Speaker Bureau / Expert testimony: Bayer; Honoraria (self), Research grant / Funding (self): Amgen; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Janssen; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Dendreon; Advisory / Consultancy, Research grant / Funding (self): Tolmar; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Astellas.

156 Background: Darolutamide ([14C]Daro) is an investigational oral androgen receptor antagonist, structurally distinct from enzalutamide ([14C]Enza) and apalutamide ([14C]Apa). In a retrospective analysis of the ARADES database, central nervous system (CNS)-related adverse events (AEs) were not linked with Daro (Fizazi, et al. 2015). CNS-related AEs have been observed with Enza and Apa, eg, fatigue, mental impairment, and seizure (Hussain et al, 2018; Smith et al, 2018). In preclinical studies, low blood–brain barrier (BBB) penetration of Daro was observed, suggesting low impact on the CNS. To understand the different CNS effects, we report in vivo tissue distribution data in rats with [14C]-labeled Apa compared to previously presented [14C]Enza and [14C]Daro distribution data (Zurth, ASCO GU 2018) using quantitative whole-body autoradiography (QWBA). Methods: Male rats were orally dosed with 10 mg/kg [14C]Apa under similar experimental conditions as previously reported for [14C]Daro or [14C]Enza, prior to QWBA. One animal was sacrificed at each timepoint: (tmax) 3h, 8h, and 24h post-dose. Timepoint selection was based on a single oral Apa dose pharmacokinetic study in rats. Results: Apa displayed good absorption and homogeneous distribution throughout the body early post-dose, comparable to previous observations for Enza and Daro. As observed for [14C]Enza, [14C]Apa remained constant in the body (t1/2 ~4h vs ~3h) up to 8h post-dose, whereas [14C]Daro was eliminated from all tissues (t1/2 ~1h). High concentrations of [14C]Apa persisted in the brain for up to 8h, although concentrations were ~2-fold lower than previously reported for [14C]Enza. [14C]Daro brain concentrations were near the lower limit of quantification, and ~26x and 46x lower than [14C]Apa and [14C]Enza brain concentrations, respectively. Conclusions: The current preclinical study demonstrated moderate BBB penetration for Apa, similar to the previous Enza data, whereas Daro displayed > 25-fold lower BBB penetration, suggesting that Daro may be less likely to induce CNS-related AEs, which is expected to be confirmed by data from the ARAMIS study.

345 Background: Darolutamide (ODM-201) (Daro) is an investigational oral and high-affinity androgen receptor antagonist. In preclinical studies, penetration of Daro through the blood–brain barrier (BBB) is negligible and in a retrospective safety analysis of the ARADES database for CNS-related adverse events (AEs), only 1 report of urinary incontinence was linked to Daro (Fizazi K, et al. 2015). Various clinical trials on enzalutamide (Enza) have reported CNS AEs (eg, seizure, falls, fatigue, pain). To understand the differences in CNS outcomes, we report an in vivo tissue distribution study with [14C]-labelled Enza and Daro in a head-to-head study in rats by means of quantitative whole-body autoradiography (QWBA). Methods: Male rats were orally dosed with 10 mg/kg [14C]Daro or [14C]Enza in the same formulation, administration volume, and radioactive dose. The animals were sacrificed at each drug’s specific tmax (time to reach the maximum concentration) in blood and brain and processed for QWBA. Results: At early time points [14C]Daro- and [14C]Enza-derived radioactivity was rapidly absorbed from the gastrointestinal tract and homogenously distributed throughout the body. By 8 h post dose, [14C]Daro was significantly eliminated from almost all organs/tissues, whereas [14C]Enza remained constant within the body. In contrast to [14C]Daro, high and persistent radioactivity was observed in brain for [14C]Enza. At tmax, the brain/blood-ratio of [14C]Enza was ~0.765, while [14C]Daro was about 10-fold lower at ~0.074. Conclusions: Results show that post dose, there was a 10-fold lower BBB penetration of [14C]Daro compared with [14C]Enza. At 8 h, [14C]Daro was rapidly eliminated and almost undetectable in all tissues, including brain, in contrast to [14C]Enza that remained constant. These data suggest that Daro might have a lower risk of inducing CNS-related AEs than Enza. Further clinical studies are ongoing.

Establishing esterase assays allows the determination and comparison of esteratic activities of tissues of one organism and between organisms. We have developed a high-performance liquid chromatography (HPLC) assay for the determination of S-acetylthiocholine (ATC) and p-nitrophenyl acetate (NPA) hydrolyzing activities of rat serum esterases based on ion pair chromatography with on-line radiochemical and ultraviolet (UV) detection. ATC is a substrate for cholinesterases, whereas NPA is cleaved by a variety of esterases and other proteins (e.g., cholinesterases, paraoxonase, carboxylesterase, albumin). Both substrates were incubated, simultaneously or separately, with rat serum to explore potential interferences between the enzymatic hydrolyses of the compounds. The ratio of the peak area of the 14C-labeled substrates to the total peak area of the substrates and their corresponding cleavage products was compared with the UV quantitation of ATC and p-nitrophenolate (NP), the cleavage product of NPA, measured at 230 and 350 nm, respectively. The peak identity of ATC and NP was confirmed by electrospray ionization–tandem mass spectrometry (ESI–MS/MS). The reaction rates of the assays using one substrate or both, as well as using radiochemical or UV detection, were equal. Moreover, the correlation between rat serum volumes and reaction rates was shown for both substrates. In conclusion, one can (i) choose between the two detection methods reliably, (ii) take advantage of monitoring both substrate and product by using radiochemical detection, and (iii) combine both substrates to determine esterase activities in rat serum and probably other biological matrices.

INTRODUCTION: A prospective, open and randomized, two-way crossover study was conducted to evaluate the pharmacokinetics and bioavailability of oral fludarabine phosphate when taken on a full versus an empty stomach. The effectiveness of therapy was also assessed after two cycles of treatment, four weeks apart MATERIALS AND METHODS: Patients with chronic lymphocytic leukemia or low-grade non-Hodgkin's lymphoma were randomly assigned to two groups, both of which received two cycles of treatment with 90 mg of oral fludarabine phosphate administered when either fed or fasted. Patients in Group 1 (n = 8) received oral treatment on a full stomach for the first cycle then on a fasted stomach for the second, while those in Group 2 (n = 10) received their treatment in the reverse sequence. Oral fludarabine phosphate was administered on the first day of the two study cycles and intravenous fludarabine phosphate was administered on days 3-6. RESULTS AND CONCLUSION: Of 22 patients recruited, 18 (CLL n = 10; NHL n = 8) were eligible for efficacy and safety evaluation, and 16 for bioavailability and pharmacokinetic analyses. The response to oral 2-F-ara-AMP was rapid: by two treatment cycles, 12 out of 18 patients (66.7%) had achieved partial response. Of the six patients who did not respond, five patients (27.7%) had stable disease. There was no notable difference in the rate of response between patients with B-CLL and lg-NHL. There was a marginal increase in total systemic availability of fludarabine phosphate when administered orally on a fed stomach (2-F-ara-A AUC((0-24 h)) = 3.28 +/- 1.48 microg.h/ml) compared to a fasted stomach (2-F-ara-A AUC((0-24 h)) = 3.05 +/- 1.56 microg.h/ml). Time to peak plasma concentration was slightly extended by the presence of food (2.2 +/- 1.0 versus 1.3 +/- 0.74 h) but the terminal half-life was unaffected. The minor differences in the pharmacokinetics of oral fludarabine phosphate when taken after food were not statistically significantly different and seem unlikely to be clinically relevant. The efficacy and safety data closely paralleled previous experience with the intravenous formulation.

Expression of human cytochrome P450 (CYP) in heterologous cells is a means of specifically studying the role of these enzymes in drug metabolism. The complete cDNA encoding CYP2D6-VAL 374 was inserted into an expression vector containing the strong mycloproliferative sarcoma virus promotor in combination with the enhancer of the cytomegalovirus and stably expressed in V79 Chinese hamster cells. The presence of genomically integrated CYP2D6 cDNA was confirmed by polymerase chain reaction analysis. The protein expression was shown by Western blotting. Functional expression could be demonstrated by O -demethylation of dextromethorphan to dextrorphan in live cells. The enzymatic activity of 154 ± 16 pmol min −1 mg −1 protein was comparable with dextromethorphan- O -demethylation activities of human liver. The metabolism of two dopaminergic ergoline derivatives was investigated in whole recombinant V19 cells. Both lisuride and terguride were monodeethylated; in case of lisuride a correlation to the in vivo situation was demonstrated comparing poor and extensive metabolizers.

Expression of human cytochrome (CYP) in heterologous cells is a means of specifically studying the role of these enzymes in drug metabolism. The complete cDNA encoding CYP3A4 (PCN1) was inserted into an expression vector containing the strong myeloproliferative sarcoma virus promoter in combination with the enhancer of the cytomegalovirus and stably expressed in V79 Chinese hamster cells. The presence of genomically integrated CYP3A4 cDNA cell clones was confirmed by polymerase chain reaction analysis. Transcription was detected by reverse transcribed polymerase chain reaction analysis. Functional expression could be demonstrated by conversion of testosterone to the specific 6beta-hydroxylated product. In recombinant V79 cells expressing CYP3A4 about 6% of the substrate was converted to 6beta-hydroxytestosterone. The metabolism of two dopaminergic ergot derivatives was investigated in live recombinant V79 cells. Both lisuride and terguride were monodeethylated.