Therapeutic Monitoring of Palbociclib, Ribociclib, Abemaciclib, M2, M20, and Letrozole in Human Plasma: A Novel LC-MS/MS Method.

BACKGROUND: Therapeutic drug monitoring (TDM) using cyclin-dependent kinase inhibitors (CDK4/6is) is a novel approach for optimizing treatment outcomes. Currently, palbociclib, ribociclib, and abemaciclib are the available CDK4/6is and are primarily coadministered with letrozole. This study aimed to develop and validate an LC-MS/MS method for the simultaneous analysis of CDK4/6is, 2 active metabolites of abemaciclib (M2 and M20), and letrozole in human plasma for use in TDM studies. METHODS: Sample pretreatment comprised protein precipitation with methanol and dilution of the supernatant with an aqueous mobile phase. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column (2.5 µm, 3.0 × 75 mm XP), with methanol serving as the organic mobile phase and pyrrolidine-pyrrolidinium formate (0.005:0.005 mol/L) buffer (pH 11.3) as the aqueous mobile phase. A triple quadrupole mass spectrometer was used for the detection, with the ESI source switched from negative to positive ionization mode and the acquisition performed in multiple reaction monitoring mode. RESULTS: The complete validation procedure was successfully performed in accordance with the latest regulatory guidelines. The following analytical ranges (ng/mL) were established for the tested compounds: 6-300, palbociclib and letrozole; 120-6000, ribociclib; 40-800, abemaciclib; and 20-400, M2 and M20. All results met the acceptance criteria for linearity, accuracy, precision, selectivity, sensitivity, matrix effects, and carryover. A total of 85 patient samples were analyzed, and all measured concentrations were within the validated ranges. The percent difference for the reanalyzed samples ranged from -11.2% to 7.0%. CONCLUSIONS: A simple and robust LC-MS/MS method was successfully validated for the simultaneous quantification of CDK4/6is, M2, M20, and letrozole in human plasma. The assay was found to be suitable for measuring steady-state trough concentrations of the analytes in patient samples.

Strategy to Improve the Oral Pharmacokinetics of Cyclin-Dependent Kinase 4/6 Inhibitors: Enhancing Permeability and CYP450 Inhibition by a Natural Bioenhancer.

Palbociclib and ribociclib an orally bioavailable, potent cyclin-dependent kinase 4/6 inhibitors, with low oral bioavailability due to substrate specificity towards CYP3A and P-glycoprotein. Thus, current research aims to examine the effect of a bioenhancer (naringin), on oral pharmacokinetics of palbociclib and ribociclib. Naringin's affinity for CYP3A4 and P-glycoprotein was studied using molecular docking; its impact on palbociclib/ribociclib CYP3A metabolism and P-glycoprotein-mediated efflux was examined using in vitro preclinical models; and its oral pharmacokinetics in rats were assessed following oral administration of palbociclib/ribociclib in presence of naringin (50 and 100 mg/kg). Naringin binds optimally to both proteins with the highest net binding energy of - 1477.23 and - 1607.47 kcal/mol, respectively. The microsomal intrinsic clearance of palbociclib and ribociclib was noticeably reduced by naringin (5-100 µM), by 3.0 and 2.46-folds, respectively. Similarly, naringin had considerable impact on the intestinal transport and efflux of both drugs. The pre-treatment with 100 mg/kg naringin increased significantly (p < 0.05) the oral exposure of palbociclib (2.0-fold) and ribociclib (1.95-fold). Naringin's concurrent administration of palbociclib and ribociclib increased their oral bioavailability due to its dual inhibitory effect on CYP3A4 and P-glycoprotein; thus, concurrent naringin administration may represent an innovative strategy for enhancing bioavailability of cyclin-dependent kinase inhibitors.

Validated HPLC-UV method for simultaneous quantification of phosphatidylinositol 3-kinase inhibitors, copanlisib, duvelisib and idelalisib, in rat plasma: Application to a pharmacokinetic study in rats.

Phosphatidylinositol 3-kinase (PI3K) inhibitors are a novel class of anticancer drugs that are approved to treat various malignancies. We report the development and validation of a HPLC method for the simultaneous quantitation of three PI3K inhibitors, namely copanlisib, duvelisib and idelalisib, in rat plasma as per the regulatory guidelines of the United States Food and Drug Administration. The method involves extraction of copanlisib, duvelisib and idelalisib along with an internal standard (IS; filgotinib) from rat plasma (100 µL) using a liquid-liquid extraction process. The chromatographic separation of the analytes was achieved using step-wise gradient elution on a Hypersil Gold C18 column. The UV detection wavelength was set at λmax = 280 nm. Copanlisib, duvelisib, idelalisib and the IS eluted at 7.16, 12.6, 11.9 and 9.86 min, respectively, with a total run time of 15 min. The calibration curve ranged from 50 to 5000 ng/mL for all the analytes. Inter- and intra-day precision and accuracy, stability studies, dilution integrity and incurred sample reanalysis were investigated for all three analytes, and the results met the acceptance criteria. The validated HPLC method was successfully applied to a pharmacokinetic study in rats.

Development of Sustained Release Baricitinib Loaded Lipid-Polymer Hybrid Nanoparticles with Improved Oral Bioavailability.

Baricitinib (BTB) is an orally administered Janus kinase inhibitor, therapeutically used for the treatment of rheumatoid arthritis. Recently it has also been approved for the treatment of COVID-19 infection. In this study, four different BTB-loaded lipids (stearin)-polymer (Poly(d,l-lactide-co-glycolide)) hybrid nanoparticles (B-PLN1 to B-PLN4) were prepared by the single-step nanoprecipitation method. Next, they were characterised in terms of physicochemical properties such as particle size, zeta potential (ζP), polydispersity index (PDI), entrapment efficiency (EE) and drug loading (DL). Based on preliminary evaluation, the B-PLN4 was regarded as the optimised formulation with particle size (272 ± 7.6 nm), PDI (0.225), ζP (-36.5 ± 3.1 mV), %EE (71.6 ± 1.5%) and %DL (2.87 ± 0.42%). This formulation (B-PLN4) was further assessed concerning morphology, in vitro release, and in vivo pharmacokinetic studies in rats. The in vitro release profile exhibited a sustained release pattern well-fitted by the Korsmeyer-Peppas kinetic model (R2 = 0.879). The in vivo pharmacokinetic data showed an enhancement (2.92 times more) in bioavailability in comparison to the normal suspension of pure BTB. These data concluded that the formulated lipid-polymer hybrid nanoparticles could be a promising drug delivery option to enhance the bioavailability of BTB. Overall, this study provides a scientific basis for future studies on the entrapment efficiency of lipid-polymer hybrid systems as promising carriers for overcoming pharmacokinetic limitations.

Duvelisib, a novel oral dual inhibitor of PI3K-δ,γ, is clinically active in advanced hematologic malignancies.

Duvelisib is an oral dual inhibitor of phosphoinositide 3-kinase-δ (PI3K-δ) and PI3K-γ in late-stage clinical development for hematologic malignancy treatment. This phase 1 study evaluated maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics (PD), efficacy, and safety of duvelisib in 210 patients with advanced hematologic malignancies. In the dose escalation phase (n = 31), duvelisib 8 to 100 mg twice daily was administered, with MTD determined as 75 mg twice daily. In the expansion phase (n = 179), patients with indolent non-Hodgkin lymphoma (iNHL), chronic lymphocytic leukemia (CLL), or T-cell lymphoma (TCL) were treated with 25 or 75 mg duvelisib twice daily continuously. Single-dose duvelisib was rapidly absorbed (time to maximum concentration, 1-2 hours), with a half-life of 5.2 to 10.9 hours. PD results showed inhibition of phospho-AKT (S473) in CLL tumor cells following a single dose and near-complete inhibition of CLL proliferation (Ki-67) by cycle 2. Clinical responses were seen across a range of doses and disease subtypes: iNHL overall response rate, 58% (n = 31) with 6 complete responses (CRs); relapsed/refractory CLL, 56% (n = 55) with 1 CR; peripheral TCL, 50% (n = 16) with 3 CR; and cutaneous TCL, 32% (n = 19). Median time to response was ∼1.8 months. Severe (grade ≥3) adverse events occurred in 84% of patients: neutropenia (32%), alanine transaminase increase (20%), aspartate transaminase increase (15%), anemia and thrombocytopenia (each 14%), diarrhea (11%), and pneumonia (10%). These data support further investigation of duvelisib in phase 2 and 3 studies. This trial was registered at clinicaltrials.gov as #NCT01476657.

Activity of the PI3K-δ,γ inhibitor duvelisib in a phase 1 trial and preclinical models of T-cell lymphoma.

Duvelisib (IPI-145) is an oral inhibitor of phosphatidylinositol 3-kinase (PI3K)-δ/γ isoforms currently in clinical development. PI3K-δ/γ inhibition may directly inhibit malignant T-cell growth, making duvelisib a promising candidate for patients with peripheral (PTCL) or cutaneous (CTCL) T-cell lymphoma. Inhibition of either isoform may also contribute to clinical responses by modulating nonmalignant immune cells. We investigated these dual effects in a TCL cohort from a phase 1, open-label study of duvelisib in patients with relapsed or refractory PTCL (n = 16) and CTCL (n = 19), along with in vitro and in vivo models of TCL. The overall response rates in patients with PTCL and CTCL were 50.0% and 31.6%, respectively (P = .32). There were 3 complete responses, all among patients with PTCL. Activity was seen across a wide spectrum of subtypes. The most frequently observed grade 3 and 4 adverse events were transaminase increases (40% alanine aminotransferase, 17% aspartate aminotransferase), maculopapular rash (17%), and neutropenia (17%). Responders and nonresponders had markedly different changes in serum cytokine profiles induced by duvelisib. In vitro, duvelisib potently killed 3 of 4 TCL lines with constitutive phospho-AKT (pAKT) vs 0 of 7 lines lacking pAKT (P = .024) and exceeded cell killing by the PI3K-δ-specific inhibitor idelalisib. Administration of duvelisib to mice engrafted with a PTCL patient-derived xenograft resulted in a shift among tumor-associated macrophages from the immunosuppressive M2-like phenotype to the inflammatory M1-like phenotype. In summary, duvelisib demonstrated promising clinical activity and an acceptable safety profile in relapsed/refractory TCL, as well as preclinical evidence of both tumor cell-autonomous and immune-mediated effects. This trial was registered at www.clinicaltrials.gov as #NCT01476657.

A phase I/II study of ribociclib following radiation therapy in children with newly diagnosed diffuse intrinsic pontine glioma (DIPG).

PURPOSE: Cyclin-dependent kinase-retinoblastoma (CDK-RB) pathway is dysregulated in some diffuse intrinsic pontine gliomas (DIPG). We evaluated safety, feasibility, and early efficacy of the CDK4/6-inhibitor ribociclib, administered following radiotherapy in newly-diagnosed DIPG patients. METHODS: Following radiotherapy, eligible patients received ribociclib in 28-day cycles (350 mg/m2; 21 days on/7 days off). Feasibility endpoints included tolerability for at least 6 courses, and a less than 2-week delay in restarting therapy after 1 dose reduction. Early efficacy was measured by 1-year and median overall survival (OS). Patient/parent-by-proxy reported outcomes measurement information system (PROMIS) assessments were completed prospectively. RESULTS: The study included 10 evaluable patients, 9 DIPG and 1 diffuse midline glioma (DMG)-all 3.7 to 19.8 years of age. The median number of courses was 8 (range 3-14). Three patients required dose reduction for grade-4 neutropenia, and 1 discontinued therapy for hematological toxicity following course 4. The most common grade-3/4 toxicity was myelosuppression. After 2 courses, MRI evaluations in 4 patients revealed increased necrotic volume, associated with new neurological symptoms in 3 patients. The 1-year and median OS for DIPG was 89% and 16.1 months (range 10-30), respectively; the DMG patient died at 6 months post-diagnosis. Five patients donated brain tissue and tumor; 3 were RB+ . CONCLUSIONS: Ribociclib administered following radiotherapy is feasible in DIPG and DMG. Increased tumor necrosis may represent a treatment effect. These data warrant further prospective volumetric analyses of tumors with necrosis. Feasibility and stabilization findings support further investigation of ribociclib in combination therapies. TRIAL REGISTRATION: NCT02607124.

Phase 1b study to investigate the safety and tolerability of idelalisib in Japanese patients with relapsed/refractory follicular lymphoma and chronic lymphocytic leukemia.

OBJECTIVE: Idelalisib is an orally administered, highly selective inhibitor of phosphatidylinositol 3-kinase-δ. In this phase 1b study, the safety, tolerability and pharmacokinetics of idelalisib, an oral inhibitor of phosphatidylinositol 3-kinase-δ, were evaluated in Japanese patients with relapsed or refractory indolent B-cell non-Hodgkin lymphoma. METHODS: In total, six patients (follicular lymphoma: n = 3, chronic lymphocytic leukemia: n = 3) were enrolled to receive idelalisib 150 mg twice daily. RESULTS: No dose-limiting toxicities were reported. The most common adverse events were diarrhea (n = 5), gastritis (n = 3), insomnia (n = 3) and pyrexia (n = 3). The most common ≥grade 3 adverse events were diarrhea (n = 2), increased transaminase levels (n = 2) and decreased appetite (n = 2). The maximum idelalisib plasma concentrations (Cmax) were achieved at 2.50 h (range: 1.50-4.00 h). The mean idelalisib plasma concentrations decreased over time but remained detectable in most patients at 12 h. All enrolled patients underwent efficacy evaluation by investigators, and five patients (follicular lymphoma: n = 2, chronic lymphocytic leukemia: n = 3) achieved partial response. The median duration of partial response was 14.5 months (range: 3.7-31.3 months). CONCLUSION: Idelalisib 150 mg twice daily was considered tolerable in Japanese patients with follicular lymphoma or chronic lymphocytic leukemia.(Clinical trial registration: NCT02242045).

Current Understanding of the Intestinal Absorption of Nucleobases and Analogs.

It has long been suggested that a Na+-dependent carrier-mediated transport system is involved in the absorption of nucleobases and analogs, including some drugs currently in therapeutic use, for their uptake at the brush border membrane of epithelial cells in the small intestine, mainly based on studies in non-primate experimental animals. The presence of this transport system was indeed proved by the recent identification of sodium-dependent nucleobase transporter 1 (SNBT1/Slc23a4) as its molecular entity in rats. However, this transporter has been found to be genetically deficient in humans and higher primates. Aware of this deficiency, we need to revisit the issue of the absorption of these compounds in the human small intestine so that we can understand the mechanisms and gain information to assure the more rational use and development of drugs analogous to nucleobases. Here, we review the current understanding of the intestinal absorption of nucleobases and analogs. This includes recent knowledge about the efflux transport of those compounds across the basolateral membrane when exiting epithelial cells, following brush border uptake, in order to complete the overall absorption process; the facilitative transporters of equilibrative nucleoside transporter 1 (ENT1/SLC29A1) and equilibrative nucleobase transporter 1 (ENBT1/SLC43A3) may be involved in that in many animal species, including human and rat, without any major species differences.

Tofacitinib and Baricitinib Are Taken up by Different Uptake Mechanisms Determining the Efficacy of Both Drugs in RA.

BACKGROUND: Rheumatoid arthritis (RA) is a systemic autoimmune disease in which synovial fibroblasts (SF) play a key role. Baricitinib and Tofacitinib both act intracellularly, blocking the ATP-binding side of JAK proteins and thereby the downstream signalling pathway via STAT-3. Therefore, we investigated the role of organic cation transporters (OCTs) in Baricitinib and Tofacitinib cellular transport. METHODS: OCT expression was analysed in SF isolated from RA and osteoarthritis (OA) patients, as well as peripheral blood mononuclear cells. The interaction of Baricitinib and Tofacitinib with OCTs was investigated using quenching experiments. The intracellular accumulation of both drugs was quantified using LC/MS. Target inhibition for both drugs was tested using Western blot for phosphorylated JAK1 and STAT3 upon stimulation with IL-6. RESULTS: MATE-1 expression increased in OASF compared to RASF. The other OCTs were not differentially expressed. The transport of Baricitinib was not OCT dependent. Tofacitinib; however, was exported from RASF in a MATE-1 dependent way. Tofacitinib and Baricitinib showed comparable inhibition of downstream signalling pathways. CONCLUSION: We observed different cellular uptake strategies for Baricitinib and Tofacitinib. Tofacitinib was exported out of healthy cells due to the increased expression of MATE1. This might make Tofacitinib the favourable drug.

A Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry Quantitative Method for Determination of Baricitinib in Plasma, and Its Application in a Pharmacokinetic Study in Rats.

Baricitinib, is a selective and reversible Janus kinase inhibitor, is commonly used to treat adult patients with moderately to severely active rheumatoid arthritis (RA). A fast, reproducible and sensitive method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of baricitinib in rat plasma has been developed. Irbersartan was used as the internal standard (IS). Baracitinib and IS were extracted from plasma by liquid-liquid extraction using a mixture of n-hexane and dichloromethane (1:1) as extracting agent. Chromatographic separation was performed using Acquity UPLC HILIC BEH 1.7 µm 2.1 × 50 mm column with the mobile phase consisting of 0.1% formic acid in acetonitrile and 20 mM ammonium acetate (pH 3) (97:3). The electrospray ionization in the positive-mode was used for sample ionization in the multiple reaction monitoring mode. Baricitinib and the IS were quantified using precursor-to-production transitions of m/z 372.15 > 251.24 and 429.69 > 207.35 for baricitinib and IS, respectively. The method was validated according to the recent FDA and EMA guidelines for bioanalytical method validation. The lower limit of quantification was 0.2 ng/mL, whereas the intra-day and inter-day accuracies of quality control (QCs) samples were ranged between 85.31% to 89.97% and 87.50% to 88.33%, respectively. Linearity, recovery, precision, and stability parameters were found to be within the acceptable range. The method was applied successfully applied in pilot pharmacokinetic studies.

Management of adverse events associated with idelalisib treatment in chronic lymphocytic leukemia and follicular lymphoma: A multidisciplinary position paper.

The introduction of new therapeutic agents in chronic lymphocytic leukemia (CLL) and follicular lymphoma (FL), including the new kinase inhibitor idelalisib, has changed the therapeutic landscape of these diseases. However, the use of idelalisib is associated with a peculiar profile of side effects, which require an optimization of the current approach to prophylaxis and supportive treatment. Moving from the recognition that the abovementioned issue represents an unmet need in CLL and FL, a multidisciplinary panel of experts was convened to produce a consensus document aiming to provide practical recommendations for the management of the side effects during idelalisib therapy for CLL and FL. The present publication represents a consensus document from a series of meetings held during 2017. The Panel generated clinical key questions using the criterion of clinical relevance through a Delphi process and explored 4 domains, ie, diarrhea/colitis, transaminitis, pneumonitis, and infectious complications. Using the consensus method, the Panel was able to shape recommendations which may assist hematologist to minimize adverse events and guarantee adherence to treatment in patients with CLL and FL candidate to receive idelalisib.

P-glycoprotein Limits Ribociclib Brain Exposure and CYP3A4 Restricts Its Oral Bioavailability.

Ribociclib is a CDK4/6 inhibitor recently approved for the treatment of some types of breast cancer in combination with an aromatase inhibitor. It is currently investigated in the clinic to treat other malignancies, including brain tumors. Using in vitro and genetically modified mouse models, we investigated the effect of the multidrug efflux transporters ABCB1 and ABCG2, and the drug-metabolizing CYP3A enzymes on ribociclib pharmacokinetics and tissue distribution. In vitro, ribociclib was avidly transported by human ABCB1, but not by human ABCG2 and only modestly by mouse Abcg2. Upon oral administration at 20 mg/kg, the plasma AUC0-24h of ribociclib was increased by 2.3-fold, and its terminal elimination was delayed in Abcb1a/1b-/-;Abcg2-/- compared to wild-type mice. The brain-to-plasma ratios of ribociclib were increased by at least 23-fold relative to wild-type mice in Abcb1a/1b-/-;Abcg2-/- and Abc1a/1b-/- mice, but not noticeably in Abcg2-/- mice. Oral coadministration of elacridar, an ABCB1 and ABCG2 inhibitor, increased the brain penetration of ribociclib in wild-type mice to the same level as seen in Abcb1a/1b-/-;Abcg2-/- mice. Plasma exposure of ribociclib further decreased by 3.8-fold when transgenic human CYP3A4 was overexpressed in Cyp3a-deficient mice. Ribociclib penetration into the brain is thus drastically limited by ABCB1 in the blood-brain barrier, but coadministration of elacridar can fully reverse this process. Moreover, human CYP3A4 can extensively metabolize ribociclib and strongly restrict its oral bioavailability. The insights obtained from this study may be useful to further optimize the clinical application of ribociclib, especially for the treatment of (metastatic) brain tumors.

Tumor pharmacokinetics and pharmacodynamics of the CDK4/6 inhibitor ribociclib in patients with recurrent glioblastoma.

INTRODUCTION: We conducted a phase Ib study (NCT02345824) to determine whether ribociclib, an inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), penetrates tumor tissue and modulates downstream signaling pathways including retinoblastoma protein (Rb) in patients with recurrent glioblastoma (GBM). METHODS: Study participants received ribociclib (600 mg QD) for 8-21 days before surgical resection of their recurrent GBM. Total and unbound concentrations of ribociclib were measured in samples of tumor tissue, plasma, and cerebrospinal fluid (CSF). We analyzed tumor specimens obtained from the first (initial/pre-study) and second (recurrent/on-study) surgery by immunohistochemistry for Rb status and downstream signaling of CDK4/6 inhibition. Participants with Rb-positive recurrent tumors continued ribociclib treatment on a 21-day-on, 7-day-off schedule after surgery, and were monitored for toxicity and disease progression. RESULTS: Three participants with recurrent Rb-positive GBM participated in this study. Mean unbound (pharmacologically active) ribociclib concentrations in plasma, CSF, MRI-enhancing, MRI-non-enhancing, and tumor core regions were 0.337 µM, 0.632 µM, 1.242 nmol/g, 0.484 nmol/g, and 1.526 nmol/g, respectively, which exceeded the in vitro IC50 (0.04 µM) for inhibition of CDK4/6 in cell-free assay. Modulation of pharmacodynamic markers of ribociclib CDK 4/6 inhibition in tumor tissues were inconsistent between study participants. No participants experienced serious adverse events, but all experienced early disease progression. CONCLUSIONS: This study suggests that ribociclib penetrated recurrent GBM tissue at concentrations predicted to be therapeutically beneficial. Our study was unable to demonstrate tumor pharmacodynamic correlates of drug activity. Although well tolerated, ribociclib monotherapy seemed ineffective for the treatment of recurrent GBM.

Ribociclib in HR+/HER2- Advanced or Metastatic Breast Cancer Patients.

OBJECTIVE: To review the chemistry, pharmacology, pharmacokinetics, safety, and efficacy of ribociclib (LEE011, Kisqali) in hormone receptor-positive/human epidermal growth factor receptor-2-negative (HR+/HER2-) metastatic breast cancer. DATA SOURCES: A PubMed search was performed using the terms 'Ribociclib', 'Kisqali', and 'LEE011' between May 2018 and November 2018. References of published articles and reviews were also assessed for additional information. STUDY SELECTION AND DATA EXTRACTION: English-language preclinical and clinical studies on the chemistry, pharmacology, pharmacokinetics, safety, and efficacy of ribociclib were evaluated. DATA SYNTHESIS: Ribociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, is Food and Drug Administration (FDA) approved in combination with endocrine therapy for treatment of HR+/HER2- advanced or metastatic breast cancer in premenopausal/perimenopausal and postmenopausal women. Three phase III trials have evaluated ribociclib in combination with endocrine therapy, including letrozole, anastrozole, tamoxifen, and fulvestrant. These studies found that ribociclib 600 mg/d, 21 days on, 7 days off, leads to a significantly greater median progression-free survival (PFS), ranging from 8 to 13 months. Ribociclib is well tolerated in elderly patients, maintains health-related quality of life, and significantly reduces pain scores. The dose-limiting toxicities found in phase I studies were neutropenia, thrombocytopenia, and QTc prolongation. Common adverse effects seen in phase III trials include neutropenia, leukopenia, nausea, diarrhea, vomiting, and fatigue. Relevance to Patient Care and Clinical Practice: Literature on the safety and efficacy of ribociclib as well as its place in therapy in comparison to other FDA-approved CDK4/6 inhibitors for breast cancer is discussed. CONCLUSIONS: Ribociclib, when added to endocrine therapy, significantly improves PFS and has manageable toxicity in premenopausal/perimenopausal and postmenopausal women with HR+/HER2- advanced breast cancer.

Simultaneous determination of idelalisib and its metabolite GS-563117 in dog plasma by LC-MS/MS: Application to a pharmacokinetic study.

The purpose of this study was to develop and validate an LC-MS/MS method for simultaneous determination of idelalisib and GS-563117 in dog plasma. The analytes were extracted using ethyl acetate and then separated on a Waters Acquity UPLC BEH C18 column (50 × 2.1 mm, i. d., 1.7 µm) using 0.1% formic acid in water and acetonitrile as mobile phase at a flow rate of 0.3 mL/min in gradient elution mode. The analytes were quantified using selected reaction monitoring with precursor-to-product transitions at m/z 416.2 → 176.1, m/z 432.2 → 192.1 and m/z 421.2 → 176.1 for idelalisib, GS-563117 and [2 H5 ]-idelalisib (internal standard). The assay showed good linearity (r > 0.9992) over the tested concentration range of 0.1-600 ng/mL for idelalisib and 0.1-300 ng/mL for GS-563117. The intra- and inter-day RSD values for idelalisib and GS-563117 were <8.84 and 12.41%, respectively. The intra- and inter-day RE values were within the range of -7.21-8.52%, and -6.44-14.23%, respectively. The extraction recovery was found to be >84.59% and no matrix effects were observed. The validated LC-MS/MS method has been successfully applied for the simultaneous determination of idelalisib and GS-563117 in a pharmacokinetic study in dogs. Our results suggested that idelalisib was rapidly metabolized into its metabolite GS-563117 in dog and the in vivo exposure of GS-563117 was 17.59% of that of idelalisib.

First-in-human study of the epichaperome inhibitor PU-H71: clinical results and metabolic profile.

Background Molecular chaperone targeting has shown promise as a therapeutic approach in human cancers of various histologies and genetic backgrounds. The purine-scaffold inhibitor PU-H71 (NSC 750424), selective for Hsp90 in epichaperome networks, has demonstrated antitumor activity in multiple preclinical cancer models. The present study was a first in-human trial of PU-H71 aimed at establishing its safety and tolerability and characterizing its pharmacokinetic (PK) profile on a weekly administration schedule in human subjects with solid tumors refractory to standard treatments. Methods PU-H71 was administered intravenously over 1 h on days 1 and 8 of 21-day cycles in patients with refractory solid tumors. Dose escalation followed a modified accelerated design. Blood and urine were collected during cycles 1 and 2 for pharmacokinetics analysis. Results Seventeen patients were enrolled in this trial. Grade 2 and 3 adverse events were observed but no dose limiting toxicities occurred, thus the human maximum tolerated dose was not determined. The mean terminal half-life (T1/2) was 8.4 ± 3.6 h, with no dependency to dose level. A pathway for the metabolic disposal of PU-H71 in humans was derived from microsome studies. Fourteen patients were also evaluable for clinical response; 6 (35%) achieved a best response of stable disease for >2 cycles, with 2 patients remaining on study for 6 cycles. The study closed prematurely due to discontinuation of drug supply. Conclusions PU-H71 was well tolerated at the doses administered during this study (10 to 470 mg/m2/day), with no dose limiting toxicities.

Duvelisib, an oral dual PI3K-δ,γ inhibitor, shows clinical and pharmacodynamic activity in chronic lymphocytic leukemia and small lymphocytic lymphoma in a phase 1 study.

Duvelisib (IPI-145), an oral, dual inhibitor of phosphoinositide-3-kinase (PI3K)-δ and -γ, was evaluated in a Phase 1 study in advanced hematologic malignancies, which included expansion cohorts in relapsed/refractory (RR) chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and treatment-naïve (TN) CLL. Per protocol, TN patients were at least 65 years old or had a del(17p)/TP53 mutation. Duvelisib was administered twice daily (BID) in 28-day cycles at doses of 8-75 mg in RR patients (n = 55) and 25 mg in TN patients (n = 18.) Diarrhea was the most common nonhematologic AE (TN 78%, RR 47%); transaminase elevations the most frequent lab-abnormality AE (TN 33.3%, RR 30.9%); and neutropenia the most common ≥grade 3 AE (RR 44%, TN 33%). The overall response rates were 56.4% for RR patients (1.8% CR, 54.5% PR) and 83.3% for TN patients (all PRs); median response duration was 21.0 months in RR patients but was not reached for TN patients. Based upon phase 1 efficacy, pharmacodynamics, and safety, duvelisib 25 mg BID was selected for further investigation in a phase 3 study in RR CLL/SLL.

Influence of hemodialysis on regadenoson clearance in an in vitro hemodialysis model.

BACKGROUND: Regadenoson is a novel pharmacological stress agent whose disposition during hemodialysis is not known. The purpose of this study was to determine the clearance of regadenoson under varying dialytic conditions using an in vitro hemodialysis model. METHODS AND RESULTS: Whole human blood was used to analyze the effect of hemodialysis on the clearance of regadenoson. Regadenoson transmembrane clearance (CLD) was assessed for both a standard permeability and a high permeability polysulfone hemodialyzer with blood/dialysate flow rates of 300/600 and 400/800 mL/min. A two-tailed, paired Student's t test was used to compare regadenoson CLD between hemodialyzer types and flow rates. The mean ± SD regadenoson CLD values ranged between 62.5 ± 11.8 and 89.1 ± 24.0 mL/min for all dialytic conditions. There was no significant difference in regadenoson CLD between hemodialyzer types and flow rates (p > .05). CONCLUSIONS: Hemodialysis enhances the clearance of regadenoson independent of hemodialyzer permeability and blood/dialysate flow rate. This clearance is modest relative to total body clearance and is unlikely to produce a clinically significant outcome.

Regadenoson use in chronic kidney disease and end-stage renal disease: A focused review.

Regadenoson is a selective A2A adenosine receptor agonist that has been approved as a vasodilator stress agent with single-photon emission-computed tomography (SPECT) myocardial perfusion imaging (MPI). Since its approval by the Food and Drug Administration (FDA) in 2008, it has become the most commonly used pharmacologic stress agent with SPECT-MPI. Given that it is predominantly renally excreted, its use in patients with chronic kidney disease has been the subject of active post-marketing clinical research. Until recently, prescribing information regarding the use of regadenoson in patients with end-stage renal disease (ESRD) was not defined in the package insert. Based on accumulating data since its initial approval, the FDA has recently outlined the use of regadenoson in patients with ESRD in a label update on January 17, 2017. In this review, we discuss the evidence leading to the recent label update, focusing on the pharmacokinetics of regadenoson in patients with impaired kidney function, the safety and tolerability of regadenoson in patients with chronic kidney disease and ESRD, and the prognostic value of regadenoson stress MPI in this patient population.