CDC-like kinases (CLK) and dual-specificity tyrosine-regulated kinases (DYRK) are protein kinases involved in various cellular functions, mRNA splicing, and DNA damage repair. CLK/DYRK kinases have been implicated in many disorders such as diabetes, neurodegenerative diseases, and cancer. Cirtuvivint (SM08502) is an orally bioavailable, first-in-class pan-CLK and pan-DYRK inhibitor that modulates pre-mRNA splicing and has shown the ability to inhibit cancer cell growth in vitro and reduce tumor burden in vivo. This has led to the administration of cirtuvivint in phase I clinical trials. To quantitate cirtuvivint, we have developed and validated an LC-MS/MS method in human plasma. The assay is simple and robust and consists of a protein precipitation, dilute-and-shoot extraction method using 20 μL of plasma, chromatographic separation with a Phenomenex Kinetex C18, and a gradient mobile phase system consisting of 0.1% formic acid in water and acetonitrile. The chromatographic method is followed by mass spectrometric detection with a SCIEX 4500 tandem mass spectrometer. The method has a 5-min run time and is linear from 5 to 1000 ng/mL. The assay met the criteria outlined by the US Food and Drug Administration guidance for bioanalytical method validation and will support ongoing and future clinical studies defining cirtuvivint pharmacokinetics.

Deoxyuridine (dUrd) is often misincorporated into genomic DNA in cancer patients receiving antimetabolite chemotherapy. This activates base excision repair and recruits ataxia telangiectasia-mutated and Rad3-related (ATR), which coordinates DNA repair with nucleotide metabolism by facilitating ribonucleotide reductase (RNR) activity. Ceralasertib (AZD6738) is the most clinically advanced ATR inhibitor (ATRi) and may abrogate this regulatory pathway and diminish RNR-mediated deoxynucleotide triphosphate synthesis. To further understand ATRi-induced dUrd misincorporation, we developed a highly sensitive LC-MS/MS method to quantitate: deoxyuridine, uridine, guanosine, adenosine, cytidine, thymidine, deoxyguanosine, deoxyadenosine, and deoxycytidine from digested genomic DNA. Assay application was demonstrated with genomic DNA digested from multiple murine cell lines treated with ceralasertib. Chromatographic separation was achieved with an Inertsil ODS-3 (150 × 2.1 mm, 3 μm) column and a gradient elution program of 0.1% formic acid in water and 0.1% formic acid in methanol over an 18-min run time. Detection was performed on a SCIEX 6500+ tandem mass spectrometer. The method proved to be accurate (90.8%-114.2%) and precise (< 7.73% CV) across analytes. Freeze-thaw stability (106.4%-114.3%), stability for 12 months at -80°C (88.7%-113.7%), and stability for 4 h at room temperature (104.1%-114.0%) were acceptable across QCs.

BACKGROUND:Cancers that do not respond to immunotherapy typically harbor a non-T cell-inflamed tumor microenvironment (TME), characterized by the absence of type I/II interferon signaling and CD8+ T cell infiltration. We previously reported IDH1 somatic mutations were enriched in this phenotype across histologies. Mutant IDH1 (mIDH1) drives immune exclusion via metabolic reprogramming of the TME, and preclinical models show that IDH inhibition can restore anti-tumor immunity. We conducted a Phase II study assessing the preliminary activity of ivosidenib, an IDH1 inhibitor, plus nivolumab, an anti-PD1 antibody, in patients with mIDH1 advanced solid tumors (NCT04056910). METHODS:Patients with advanced or refractory mIDH1 solid tumors and no prior exposure to IDH1 inhibitor were administered ivosidenib 500 mg by mouth daily with nivolumab 480 mg intravenously every 4 weeks. A composite primary endpoint included either six-month progression-free survival (PFS6) or overall response rate (ORR). Translational analyses incorporated pharmacodynamics, proteomics, and spatial transcriptomics. RESULTS:Fifteen patients were enrolled (median age, 54 years; female, 53.3%; ECOG 1, 60%; glioma, 46.7%; R132H, 40%). Three patients (20%) met the primary endpoint. Median PFS was 1.94 months. The most common adverse events were leukopenia (67%), rash (67%), and diarrhea (33%). Treatment reduced plasma (R)-2HG, with greater reductions observed in patients who experienced clinical benefit. Exploratory serum proteomic and tumor spatial transcriptomic analyses suggested treatment-induced immune-modulatory effects. CONCLUSIONS:Ivosidenib plus nivolumab was safe with limited clinical benefit. Translational investigation highlights potential of IDH1 inhibition to alter tumor-immune interactions and provides hypotheses for future immune-checkpoint combinations.

Polyadenosine diphosphate-ribose polymerase 1 (PARP-1) and 2 (PARP-2) are key DNA repair enzymes that promote single-strand break repair via the base excision pathway. Niraparib, a PARP inhibitor, has shown clinical efficacy with the reduction of disease progression or death and progression-free survival benefit across multiple clinical trials, leading to the Food and Drug Administration (FDA) approval for the treatment of advanced and recurrent ovarian cancers. This study presents a robust and simple 5-min assay designed for the quantitation of the single agent niraparib in human plasma utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS). A 50 mu L volume of plasma was subjected to protein precipitation, followed by chromatographic separation using a Phenomenex Kinetex C18 column (2.6 mu m, 50 x 2.1 mm) and a gradient mobile phase system consisting of 0.1% formic acid in both water and acetonitrile during a 5-min run time. Mass spectrometric detection was achieved using a SCIEX 6500 + tandem mass spectrometer with electrospray positive-mode ionization. With a stable isotopic internal standard, our assay met the criteria outlined by the FDA guidance for bioanalytical method validation, demonstrating robust performance within the range from 5 to 5000 ng/mL. This assay will support future clinical studies by defining niraparib pharmacokinetics.

Castration and enzalutamide induce BCL-2 to drive therapy resistance in prostate cancer (PCa). We conducted a phase Ib trial to test that metastatic castration-resistant PCa (mCRPC) can be effectively targeted by combining enzalutamide with the BCL-2 inhibitor venetoclax. This phase Ib single-arm trial of enzalutamide (160 mg/d) with venetoclax in patients with progressive mCRPC assessed dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Three dose levels (DL) of venetoclax (DL1 at 400 mg/d; DL2 at 600 mg/d; and DL3 at 800 mg/d) were evaluated using a 3 + 3 design. We also analyzed enzalutamide and venetoclax pharmacokinetics and conducted pharmacodynamic studies in peripheral blood mononuclear cells (PBMCs) to determine the impact of venetoclax on BCL-2 expression. A total of 10 patients were enrolled across 3 DL and no DLT was observed. Mean duration on treatment was 29 weeks (range: 8–140 weeks). Treatment-related adverse events (TRAEs) were mostly grade 1–2, and Grade 3 TRAEs included fatigue (10

Ataxia-telangiectasia and Rad3-related (ATR) protein kinase is an essential regulator of the DNA damage response (DDR) at stalled and collapsed replication forks. Tuvusertib (M1774) is a selective, orally available small molecule ATR inhibitor currently in preclinical and clinical development for cancer treatment. This study presents a robust and simple 5-min assay designed for the quantification of single agent tuvusertib in human plasma utilizing liquid chromatography tandem mass spectrometry (LC-MS/MS). A 20 μL volume of plasma was subjected to protein precipitation, followed by chromatographic separation using a Phenomenex Synergi Polar-RP (4 μm, 2.1 × 50 mm) and a gradient mobile phase system consisting of 0.1% formic acid in both water and acetonitrile during a 4-min run time. Mass spectrometric detection was achieved using a SCIEX 6500+ tandem mass spectrometer with electrospray positive-mode ionization. With a stable isotopic internal standard, our assay met the criteria outlined by the Food and Drug Administration guidance for bioanalytical method validation, demonstrating robust performance within the range from 5 to 5000 ng/mL. This assay will support ongoing and future clinical studies by defining tuvusertib pharmacokinetics.

To support a phase 1 trial in patients with lymphomas, we developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for tazemetostat quantitation in 20 μL of human plasma. After protein precipitation, chromatographic separation employed a Kinetex C18 column and a gradient of 0.1% formic acid in both water and acetonitrile, during a 3-min run time. Detection was achieved using a SCIEX 6500+ tandem mass spectrometer with electrospray positive-mode ionization. Validation was based on the latest Food and Drug Administration guidance. With a stable isotopic internal standard, the assay was linear within the range of 10-5000 ng/mL and proved to be accurate (91.9%-103.7%) and precise (<4.4% imprecision). Recovery varied between 93.3% and 121.1%, and matrix effect ranged from -25.5% to -4.9%. Hemolysis, lipemia, and dilution did not impact quantitation. Plasma stability was confirmed after three freeze-thaw cycles, 24 h at room temperature, and 4 months at -80°C. Incurred sample reanalysis yielded 94.4% samples within 20% difference (n = 36). External validation showed a mean bias of -11.1%. Pharmacokinetic (PK) data obtained from three patients suggested variable concentration time profiles, warranting collection of further data. The assay proved to be suitable for tazemetostat quantitation in human plasma and will support clinical studies by defining tazemetostat PKs.

ABSTRACT Diffuse gliomas are epigenetically dysregulated, immunologically cold, and fatal tumors characterized by mutations in isocitrate dehydrogenase (IDH). Although IDH mutations yield a uniquely immunosuppressive tumor microenvironment, the regulatory mechanisms that drive the immune landscape of IDH mutant (IDHm) gliomas remain unknown. Here, we reveal that transcriptional repression of retinoic acid (RA) pathway signaling impairs both innate and adaptive immune surveillance in IDHm glioma through epigenetic silencing of retinol binding protein 1 (RBP1) and induces a profound anti-inflammatory landscape marked by loss of inflammatory cell states and infiltration of suppressive myeloid phenotypes. Restorative retinoic acid therapy in murine glioma models promotes clonal CD4 + T cell expansion and induces tumor regression in IDHm, but not IDH wildtype (IDHwt), gliomas. Our findings provide a mechanistic rationale for RA immunotherapy in IDHm glioma and is the basis for an ongoing investigator-initiated, single-center clinical trial investigating all-trans retinoic acid (ATRA) in recurrent IDHm human subjects.

The DNA-dependent protein kinase (DNA-PK) is an abundant nuclear protein that mediates DNA double-strand break repair by nonhomologous end joining (NHEJ). As such, DNA-PK is critical for V(D)J recombination in lymphocytes and for survival in cells exposed to ionizing radiation and clastogens. Peposertib (M3814) is a small molecule DNA-PK inhibitor currently in preclinical and clinical development for cancer treatment. We have developed a high-performance liquid chromatography-mass spectrometry method for quantitating peposertib and its metabolite in 0.1 mL human plasma. After MTBE liquid-liquid extraction, chromatographic separation was achieved with a Phenomenex Synergi polar reverse phase (4 μm, 2 × 50 mm) column and a gradient of 0.1% formic acid in acetonitrile and water over an 8 min run time. Mass spectrometric detection was performed on an ABI SCIEX 4000 with electrospray, positive-mode ionization. The assay was linear from 10 to 3000 ng/mL for peposertib and 1-300 ng/mL for the metabolite and proved to be both accurate (97.3%-103.7%) and precise (<8.9%CV) fulfilling criteria from the Food and Drug Administration (FDA) guidance on bioanalytical method validation. This liquid chromatography-tandem mass spectroscopy (LC-MS/MS) assay will support several ongoing clinical studies by defining peposertib pharmacokinetics.

The Ataxia Telangiectasia and Rad3-related (ATR) protein complex is an apical initiator of DNA damage response pathways. Several ATR inhibitors (ATRi) are in clinical development including berzosertib (formerly M6620, VX-970). Although clinical studies have examined plasma pharmacokinetics (PK) in humans, little is known regarding dose/exposure relationships and tissue distribution. To understand these concepts, we extensively characterized the PK of berzosertib in mouse plasma and tissues. A highly sensitive LC–MS/MS method was utilized to quantitate berzosertib in plasma and tissues. Dose proportionality was assessed in female BALB/c mice following single IV doses (2, 6, 20 or 60 mg/kg). A more extensive PK study was conducted in tumor-bearing mice following a single IV dose of 20 mg/kg to evaluate distribution to tissues. PK parameters were calculated by non-compartmental analysis (NCA). A compartmental model was developed to describe the PK behavior of berzosertib. Plasma protein binding was determined in vitro. Increased doses of berzosertib were associated with less than proportional increases in early plasma concentrations and greater than proportional increase in tissue exposure, attributable to saturation of plasma protein binding. Berzosertib extensively distributed into bone marrow, tumor, thymus, and lymph nodes, however; brain and spinal cord exposure was less than plasma. The nonlinear PK of berzosertib displayed here can be attributed to saturation of plasma protein binding and occurred at concentrations close to those observed in clinical trials. Our results will help to understand preclinical pharmacodynamic and toxicity data and to inform optimal dosing and deployment of berzosertib.

VNPP433-3β (compound 2, (3β-(1H-imidazole-1-yl)-17-(1H-benzimidazole-1-yl)-androsta-5,16-diene), a multitarget anticancer agent has emerged as our lead next generation galeterone analogs (NGGA). Compound 2 is currently in development as potential new therapeutic for prostate and pancreatic cancers. The preliminary toxicity study reveals that the compound 2 was better tolerated by the normal male CD-1 mice than the male Nude mice. The maximum tolerated dose (MTD) in the Nude mice was estimated to be between 25 < 50 mg/kg. After oral dosing of compound 2 to male and female rats, the plasma concentration versus time curves were very consistent between animals and the AUClast increased with dose. Many plasmas concentration versus time curves profiles were nearly flat over 24 hr., suggesting extended absorption from the GI tract. Consequently, reliable values for half-life and AUCinf were not determined. Calculated oral bioavailability (using oral AUClast and excluding the outlier IV animal) ranged from 32 to 47 %. This should be considered a minimum value since the contribution to true AUC beyond 24 hr. is clearly not zero. Clearly, these toxicology and pharmacokinetics parameters pave the way for understanding the anticancer pharmacological actions and provide a meaningful basis for further preclinical development and eventual clinical development.

Fluoropyridine-based chemotherapy remains the most widely used treatment for colorectal cancer (CRC). In this study, we investigated the mechanism by which the natural product Scutellaria baicalensis (Huang Qin; HQ) and one of its main components baicalin enhanced 5-fluorouracil (5-FU) antitumor activity against CRC. Cell proliferation assays, cell cycle analysis, reverse-phase protein array (RPPA) analysis, immunoblot analysis, and qRT-PCR were performed to investigate the mechanism(s) of action of HQ and its active components on growth of CRC cells. HQ exhibited in vitro antiproliferative activity against drug resistant human CRC cells, against human and mouse CRC cells with different genetic backgrounds and normal human colon epithelial cells. In vivo animal models were used to document the antitumor activity of HQ and baicalin. The mechanism of growth inhibitory activity of HQ is due to inhibition of proliferative signaling pathways including the CDK-RB pathway. In addition, HQ enhanced the antitumor effects of 5-FU and capecitabine in vivo. Furthermore, we identified baicalin as an active component of HQ. The combination of baicalin and 5-FU demonstrated synergistic activity against 5-FU-resistant RKO-R10 cells. The combination significantly inhibited in vivo tumor growth greater than each treatment alone. RPPA results showed that the signaling pathway alterations in CRC cells were similar following HQ and baicalin treatment. Together, these results indicate that HQ and its component baicalin enhance the effect of 5-fluorouracil-based chemotherapy via inhibition of CDK-RB pathway. These findings may provide the rational basis for developing agents that can overcome the development of cellular drug resistance.

Supplementary Tables 1-3. Supplemental Table 1. Plasma pharmacokinetics of DMS612 metabolites. Supplemental Table 2. Pharmacodynamic assessment of !-H2AX detection in PBMCs. Mean values for !-H2AX foci per cell with DMS612 doses of 1.5, 3, 5, 7, 9 and 12 mg/m2 at the indicated time in hours (h). Supplemental Table 3. Pharmacodynamic assessment of !-H2AX detection in hair follicles. Mean values for cell with more than 4 !-H2AX foci per cell in plucked scalp hairs with DMS612 doses of 1.5, 3 and 9 mg/m2 at the indicated time in hours (h). Supplemental Figure 1. Pharmacokinetics of DMS612 Metabolites.

PDF file - 10K, Venn Diagram, Microarray Validation.

PDF file - 8K, RT-qPCR and Confidence Intervals for Jag1.

Supplementary Data from Modular Smart Molecules for PSMA-Targeted Chemotherapy

PDF file - 53K, Confidence Intervals for RT-qPCR.

PDF file - 12K, RT-qPCR and Confidence Intervals serum free.

To support a phase III randomized trial of the multi-targeted tyrosine kinase inhibitor cabozantinib in neuroendocrine tumors, we developed a high-performance liquid chromatography mass spectrometry method to quantitate cabozantinib in 50 μL of human plasma. After acetonitrile protein precipitation, chromatographic separation was achieved with a Phenomenex synergy polar reverse phase (4 μm, 2 × 50 mm) column and a gradient of 0.1% formic acid in acetonitrile and 0.1% formic acid in water over a 5-min run time. Detection was performed on a Quattromicro quadrupole mass spectrometer with electrospray, positive-mode ionization. The assay was linear over the concentration range 50-5000 ng/mL and proved to be accurate (103.4-105.4%) and precise (<5.0%CV). Hemolysis (10% RBC) and use of heparin as anticoagulant did not impact quantitation. Recovery from plasma varied between 103.0-107.7% and matrix effect was -47.5 to -41.3%. Plasma freeze-thaw stability (97.7-104.9%), stability for 3 months at -80°C (103.4-111.4%), and stability for 4 h at room temperature (100.1-104.9%) were all acceptable. Incurred sample reanalysis of (N = 64) passed: 100% samples within 20% difference, -0.7% median difference and 1.1% median absolute difference. External validation showed a bias of less than 1.1%. This assay will help further define the clinical pharmacokinetics of cabozantinib.