Validation of a robust and rapid liquid chromatography tandem mass spectrometric method for the quantitative analysis of VK-2019, a selective EBNA1 inhibitor.

EBNA1 is an Epstein Barr virus (EBV) protein expressed in all EBV-associated cancers. EBNA1 plays a critical role in the replication and maintenance of EBV episomes in latently infected cells. VK-2019 was developed as a highly specific inhibitor of EBNA1 DNA binding activity and is currently in phase 1 development as a treatment for EBV-associated carcinomas. A sensitive and reliable method was developed to quantify VK-2019 in human plasma using liquid chromatography with tandem mass spectrometry to perform detailed pharmacokinetic studies. VK-2019 was extracted from plasma using protein precipitation with acetonitrile. Separation of VK-2019, two purported metabolites, and the internal standard, VK-2019-d6, was achieved with a Zorbax XDB C18 column using a gradient flow over 6 min. VK-2019 was detected using a SCIEX 4500 triple quadrupole mass spectrometer operating in positive electrospray ionization mode. The assay range was 0.5-500 ng/mL and proved to be accurate and precise. Dilutions of 1:10 were accurately quantified. VK-2019 was stable in plasma at -70°C for approximately 18 months. The method was applied to assess the total plasma concentrations of VK-2019 in a patient who received a single and multiple oral daily doses of 120 mg.

Phase I Study of Entinostat, Atezolizumab, Carboplatin, and Etoposide in Previously Untreated Extensive-Stage Small Cell Lung Cancer, ETCTN 10399.

BACKGROUND: CREBBP and EP300 mutations occur at a frequency of 15% and 13%, respectively, in small cell lung cancer (SCLC), and preclinical models demonstrated susceptibility to targeting with HDAC inhibitors. METHODS: Patients with treatment-naïve extensive-stage SCLC, ECOG ≤2 were enrolled and treated with entinostat orally weekly (4 dose levels, DL) in combination with standard dose carboplatin, etoposide, and atezolizumab. Cohort allocation was determined by Bayesian optimal interval (BOIN) design targeting an MTD with a DLT rate of 20%. RESULTS: Three patients were enrolled and treated at DL1 with entinostat 2 mg. Patients were aged 69-83; 2 male, 1 female; 2 were ECOG 1, and 1 was ECOG 0. The most common adverse events (AEs) were anemia (3), neutropenia (3), thrombocytopenia (2), leukopenia (2), and hypocalcemia (2). Two experienced DLTs during cycle 1: (1) grade (Gr) 4 febrile neutropenia, and (1) Gr 5 sepsis. BOIN design required stopping accrual to DL1, and the trial was closed to further accrual. Entinostat and atezolizumab pharmacokinetics were both comparable to historical controls. CONCLUSION: Addition of entinostat to atezolizumab, carboplatin, and etoposide is unsafe and resulted in early onset and severe neutropenia, thrombocytopenia. Further exploration of entinostat with carboplatin, etoposide, and atezolizumab should not be explored. (ClinicalTrials.gov Identifier: NCT04631029).

Safety and Tolerability of Carboplatin and Paclitaxel in Cancer Patients with HIV (AMC-078), an AIDS Malignancy Consortium (AMC) Study.

BACKGROUND: Persons living with human immunodeficiency virus are an underserved population for evidence-based cancer treatment. Paclitaxel and carboplatin (PCb) is an active regimen against a variety of solid tumors, including several seen in excess in patients with HIV infection. We performed a pilot trial to evaluate the safety of full-dose PCb in people living with human immunodeficiency virus and cancer. METHODS: Eligible patients, stratified by concurrent antiretroviral therapy (ART) that included CYP3A4 inhibitors or not, received paclitaxel (175 mg/m2) in combination with carboplatin (target AUC 6) intravenously every 3 weeks for up to 6 cycles. RESULTS: Sixteen evaluable patients received 64 cycles of PCb, including 6 patients treated with CYP3A4 inhibiting ART (ritonavir). The adverse event profile was consistent with the known toxicity profile of PCb, with no differences between the 2 strata. There were 4 partial responses (25%, 95% CI: 7%-52%), and overall, CD4+ lymphocyte count was similar after completion of therapy (median: 310/µL) compared with baseline values (median: 389/µL). Pharmacokinetic studies in 6 patients revealed no significant differences in Cmax or AUCinf for paclitaxel between the 2 cohorts. CONCLUSION: Full doses of PCb chemotherapy are tolerable when given concurrently with ART in people living with human immunodeficiency virus with cancer, including patients receiving CYP3A4 inhibitors. CLINICALTRIALS.GOV IDENTIFIER: NCT01249443.

Validation of a robust and rapid liquid chromatography tandem mass spectrometric method for the quantitative analysis of navitoclax.

The Bcl-2 family small molecule inhibitor navitoclax is being clinically evaluated to treat multiple cancers including lymphoid malignancies and small cell lung cancer. A sensitive and reliable method was developed to quantitate navitoclax in human plasma using liquid chromatography with tandem mass spectrometry with which to perform detailed pharmacokinetic studies. Sample preparation involved protein precipitation using acetonitrile. Separation of navitoclax and the internal standard, navitoclax-d8, was achieved with a Waters Acquity UPLC BEH C18 column using isocratic flow over a 3 min total analytical run time. A SCIEX 4500 triple quadrupole mass spectrometer operated in positive electrospray ionization mode was used for the detection of navitoclax. The assay range was 5-5,000 ng/ml and proved to be accurate (89.5-104.9%) and precise (CV ≤ 11%). Long-term frozen plasma stability for navitoclax at -70°C was at least 34 months. The method was applied for the measurement of total plasma concentration of navitoclax in a patient receiving a 250 mg daily oral dose.

Quantitation of navtemadlin in human plasma and brain tissue by liquid chromatography-tandem mass spectrometry.

Navtemadlin is an orally bioavailable small molecule that blocks the protein-protein interaction between murine double minute 2 protein (MDM2) and the tumor suppressor protein p53, leading to p53-mediated cell cycle arrest and apoptosis. It is being evaluated in clinical trials for a variety of malignancies, both as a single agent and in combination regimens. A sensitive, robust LC-tandem mass spectrometry (LC-MS/MS) method was developed to quantitate navtemadlin in plasma, and this method was also validated using brain tissue homogenate. Sample preparation involved protein precipitation of plasma or brain tissue homogenate using acetonitrile. Navtemadlin, navtemadlin glucuronide, and the internal standard, D6 -navtemadlin, were separated from microsomal incubation extracts using gradient elution and a ZORBAX XDB C18 column. Analytes were detected using a SCIEX 5500 triple quadrupole mass spectrometer in positive electrospray ionization mode. The assay range of 1-1000 ng/mL was shown to be accurate (96.1-102.0% and 95.7-104%) and precise (coefficient of variation ≤ 10.6% and ≤ 6.6%) in plasma and brain tissue homogenate, respectively. An 8000 ng/mL navtemadlin sample diluted 1:10 (v/v) with plasma was also accurately quantitated. Navtemadlin has been stable in frozen plasma at -70°C for at least 20 months. This validated LC-MS/MS method was applied to determine navtemadlin concentrations in plasma and brain tissue samples from two separate patients receiving 120 mg/day navtemadlin on protocol ABTC1604.

Targeting the Hedgehog Pathway Using Itraconazole to Prevent Progression of Barrett's Esophagus to Invasive Esophageal Adenocarcinoma.

OBJECTIVE: The aim of the study was to investigate whether inhibition of Sonic Hedgehog (SHH) pathway would prevent progression of Barrett's Esophagus (BE) to esophageal adenocarcinoma. BACKGROUND: The hedgehog signaling pathway is a leading candidate as a molecular mediator of BE and esophageal adenocarcinoma (EAC). Repurposed use of existing off-patent, safe and tolerable drugs that can inhibit hedgehog, such as itraconazole, could prevent progression of BE to EAC. METHODS: The efficacy of itraconazole was investigated using a surgical rat reflux model of Barrett's Metaplasia (BM). Weekly intraperitoneal injections of saline (control group) or itraconazole (treatment group; 200 mg/kg) were started at 24 weeks postsurgery. Esophageal tissue was harvested at 40 weeks. The role of the Hh pathway was also evaluated clinically. Esophageal tissue was harvested after 40 weeks for pathological examination and evaluation of the SHH pathway by immunohistochemistry. RESULTS: BM was present in control animals 29 of 31 (93%) versus itraconazole 22 of 24 (91%). EAC was significantly lower in itraconazole 2 of 24 (8%) versus control 10 of 31 (32%), respectively (P = 0.033). Esophageal SHH levels were lower in itraconazole vs control (P = 0.12). In esophageal tissue from humans with recurrent or persistent dysplastic BE within 24 months of ablative treatment, strong SHH and Indian Hedgehog expression occurred in distal BE versus proximal squamous epithelium, odds ratio = 6.1 (95% confidence interval: 1.6, 23.4) and odds ratio = 6.4 (95% confidence interval: 1.2, 32.8), respectively. CONCLUSION: Itraconazole significantly decreases EAC development and SHH expression in a preclinical animal model of BM. In humans, BE tissue expresses higher SHH, Indian Hedgehog, and bone morphogenic protein levels than normal squamous esophageal epithelium.

Prospective study of Lipiodol distribution as an imaging marker for doxorubicin pharmacokinetics during conventional transarterial chemoembolization of liver malignancies.

OBJECTIVES: To evaluate the prognostic potential of Lipiodol distribution for the pharmacokinetic (PK) profiles of doxorubicin (DOX) and doxorubicinol (DOXOL) after conventional transarterial chemoembolization (cTACE). METHODS: This prospective clinical trial ( ClinicalTrials.gov : NCT02753881) included 30 consecutive participants with liver malignancies treated with cTACE (5/2016-10/2018) using 50 mg DOX/10 mg mitomycin C emulsified 1:2 with ethiodized oil (Lipiodol). Peripheral blood was sampled at 10 timepoints for standard non-compartmental analysis of peak concentrations (Cmax) and area under the curve (AUC) with dose normalization (DN). Imaging markers included Lipiodol distribution on post-cTACE CT for patient stratification into 1 segment (n = 10), ≥ 2 segments (n = 10), and lobar cTACE (n = 10), and baseline enhancing tumor volume (ETV). Adverse events (AEs) and tumor response on MRI were recorded 3-4 weeks post-cTACE. Statistics included repeated measurement ANOVA (RM-ANOVA), Mann-Whitney, Kruskal-Wallis, Fisher's exact test, and Pearson correlation. RESULTS: Hepatocellular (n = 26), cholangiocarcinoma (n = 1), and neuroendocrine metastases (n = 3) were included. Stratified according to Lipiodol distribution, DOX-Cmax increased from 1 segment (DOX-Cmax, 83.94 ± 75.09 ng/mL; DN-DOX-Cmax, 2.67 ± 2.02 ng/mL/mg) to ≥ 2 segments (DOX-Cmax, 139.66 ± 117.73 ng/mL; DN-DOX-Cmax, 3.68 ± 4.20 ng/mL/mg) to lobar distribution (DOX-Cmax, 334.35 ± 215.18 ng/mL; DN-DOX-Cmax, 7.11 ± 4.24 ng/mL/mg; p = 0.036). While differences in DN-DOX-AUC remained insignificant, RM-ANOVA revealed significant separation of time concentration curves for DOX (p = 0.023) and DOXOL (p = 0.041) comparing 1, ≥ 2 segments, and lobar cTACE. Additional indicators of higher DN-DOX-Cmax were high ETV (p = 0.047) and Child-Pugh B (p = 0.009). High ETV and tumoral Lipiodol coverage also correlated with tumor response. AE occurred less frequently after segmental cTACE. CONCLUSIONS: This prospective clinical trial provides updated PK data revealing Lipiodol distribution as an imaging marker predictive of DOX-Cmax and tumor response after cTACE in liver cancer. KEY POINTS: • Prospective pharmacokinetic analysis after conventional TACE revealed Lipiodol distribution (1 vs. ≥ 2 segments vs. lobar) as an imaging marker predictive of doxorubicin peak concentrations (Cmax). • Child-Pugh B class and tumor hypervascularization, measurable as enhancing tumor volume (ETV) at baseline, were identified as additional predictors for higher dose-normalized doxorubicin Cmax after conventional TACE. • ETV at baseline and tumoral Lipiodol coverage can serve as predictors of volumetric tumor response after conventional TACE according to quantitative European Association for the Study of the Liver (qEASL) criteria.

A Prospective Study of Peritransplant Sorafenib for Patients with FLT3-ITD Acute Myeloid Leukemia Undergoing Allogeneic Transplantation.

FLT3-ITD-mutated acute myeloid leukemia (AML) remains a therapeutic challenge. FLT3 inhibition in the setting of minimal residual disease and a new immune system via allogeneic transplantation offers a promise of improved survival for these patients. We performed a prospective study of patients with FLT3-ITD AML undergoing allogeneic transplant that was conducted to evaluate the safety, tolerability, and outcome of sorafenib administered peritransplant. Sorafenib dosing was individualized, starting at 200 mg twice a day (BID), and titrated based on tolerability or toxicities until a tolerable dose was identified. Forty-four patients, with a median age of 52 years, undergoing allogeneic transplant were started on sorafenib in the peritransplant period (21 pretransplant). The median duration of post-transplant follow-up was 27.6 months (range, 5.2 to 60.4). Overall survival was 76% at both 24 and 36 months. Event-free survival at 24 and 36 months was 74% and 64%, respectively. Ten patients died in the post-transplant period, with 6 deaths due to relapsed leukemia and 4 from transplant-associated toxicity. Tolerable doses ranged from 200 mg every other day to 400 mg BID with similar exposure. Correlative studies evaluating FLT3 inhibition via a plasma inhibitory activity assay showed consistent inhibition of FLT3 at all tolerability-determined dosing levels. Sorafenib is well tolerated in the peritransplant setting irrespective of the conditioning intensity or the donor source. Our findings indicate that sorafenib dosing can be individualized in the post-transplantation setting according to patient tolerability. This approach results in effective in vivo FLT3 inhibition and yields encouraging survival results.

A phase 1 trial of the oral DNA methyltransferase inhibitor CC-486 and the histone deacetylase inhibitor romidepsin in advanced solid tumors.

BACKGROUND: Epigenetic abnormalities are manifold in all solid tumors and include changes in chromatin configuration and DNA methylation. The authors designed a phase 1 study to evaluate the oral DNA methyltransferase inhibitor CC-486 combined with the histone deacetylase inhibitor romidepsin in advanced solid tumors with dose expansion to further evaluate pharmacodynamics and possible clinical benefit of the recommended phase 2 dose (RP2D). METHODS: This was a phase 1 study with a 3 + 3 dose-escalation design and an expansion phase for patients with virally mediated cancers. The disease control rate (DCR) was the primary outcome for the expansion cohort. Correlative studies included long interspersed nucleotide element 1 (LINE-1) methylation and drug exposure in blood samples (clinicaltrials.gov identifier NCT01537744). RESULTS: Fourteen patients were enrolled in the dose-escalation portion at 3 dose levels. Three patients experienced dose-limiting toxicities; the RP2D was oral CC-486 300 mg daily on days 1 through 14 and romidepsin 8 mg/m2 on days 8 and 15. Because of slow accrual into the expansion phase, the trial was closed after 4 patients enrolled. Common toxicities of the combination included nausea (83.3%), anorexia (72.2%), fatigue (61.1%), and constipation (55.6%). There were 12 patients evaluable for response, 5 with stable disease, of whom 2 received >4 cycles; there were no responses. Exposure to CC-486 and romidepsin was consistent with prior data. LINE-1 methylation on C1D8 was significantly reduced (mean, -6.23; 95% CI, -12.23, -0.24; P = .04). CONCLUSIONS: Although, at the RP2D, the combination of CC-486 and romidepsin was tolerable, no significant anticancer activity was observed. Significant demethylation in post-treatment circulating tumor DNA and biopsies provided proof of target acquisition.

AIDS-Related Kaposi Sarcoma, Version 2.2019, NCCN Clinical Practice Guidelines in Oncology.

As treatment of HIV has improved, people living with HIV (PLWH) have experienced a decreased risk of AIDS and AIDS-defining cancers (non-Hodgkin's lymphoma, Kaposi sarcoma, and cervical cancer), but the risk of Kaposi sarcoma in PLWH is still elevated about 500-fold compared with the general population in the United States. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for AIDS-Related Kaposi Sarcoma provide diagnosis, treatment, and surveillance recommendations for PLWH who develop limited cutaneous Kaposi sarcoma and for those with advanced cutaneous, oral, visceral, or nodal disease.

Open-label study to evaluate trifluridine/tipiracil safety, tolerability and pharmacokinetics in patients with advanced solid tumours and hepatic impairment.

AIMS: Trifluridine/tipiracil (FTD/TPI) prolongs survival in refractory metastatic colorectal cancer, but limited data exist on its use in patients with hepatic impairment. This Phase I, open-label, nonrandomized study investigated the safety, tolerability and pharmacokinetics of FTD/TPI in patients with advanced solid tumours (except breast cancer) and varying degrees of hepatic impairment, to provide dosing recommendations. METHODS: Patients aged ≥18 years with advanced solid tumours and normal hepatic function, or mild, moderate or severe hepatic impairment according to National Cancer Institute criteria, were planned to be enrolled. Patients received FTD/TPI 35 mg/m2 orally twice daily on days 1-5 and 8-12 of each 28-day cycle. RESULTS: Twenty-four patients were enrolled to the normal hepatic function (n = 8) and mild (n = 10) and moderate (n = 6) hepatic impairment cohorts. Overall, 12 patients (50.0%) had at least 1 adverse event leading to study discontinuation. In the moderate hepatic impairment cohort, 5 of 6 patients experienced grade ≥ 3 elevation in bilirubin. No patients with severe hepatic impairment were enrolled. FTD area under the curve at steady state decreased by 18% and 22% in the mild and moderate cohorts, respectively; however, no clear change was observed in TPI area under the curve. CONCLUSIONS: FTD/TPI can be safely administered in patients with normal hepatic function and mild hepatic impairment, with no initial dose adjustment. FTD/TPI is not recommended for use in patients with moderate hepatic impairment because of findings of grade 3 or 4 increased blood bilirubin. Therefore, FTD/TPI is not recommended for patients with moderate or severe hepatic impairment.

Increased uptake of doxorubicin by cells undergoing heat stress does not explain its synergistic cytotoxicity with hyperthermia.

Purpose: A proposed mechanism for the enhanced effectiveness of hyperthermia and doxorubicin (Dox) combinations is increased intracellular Dox concentrations resulting from heat-induced cell stress. The purpose of this study was to determine whether specific varied Dox and heat combinations produce measurable effects greater than the additive combination, and whether these effects can be attributed to heat-induced increases in intracellular Dox concentrations. Methods: HCT116, HT29 and CT26 cells were exposed to Dox and water bath heating independently. A clonogenic survival assay was used to determine cell killing and intracellular Dox concentrations were measured in HCT116 cells with mass spectrometry. Cells were exposed to heating at 42 °C (60 min) and 0.5 µg/ml of Dox at varying intervals. Synergy was determined by curve-fitting and isobologram analysis. Results: All cell lines displayed synergistic effects of combined heating and Dox. A maximum synergistic effect was achieved with simultaneous cell exposure to Dox and heat. For exposures at 42 °C, the synergistic effect was most pronounced at Dox concentrations <0.5 µg/ml. Increased intracellular concentrations of Dox in HCT116 cells caused by heat-stress did not generate a concomitant thermal enhancement. Conclusions: Simultaneous exposure of HCT116 cells to heating and Dox is more effective than sequential exposure. Heat-induced cell responses are accompanied by increased intracellular Dox concentrations; however, clonogenic survival data do not support this as the cause for synergistic cytotoxicity.

Cancer in People Living With HIV, Version 1.2018, NCCN Clinical Practice Guidelines in Oncology.

People living with HIV (PLWH) are diagnosed with cancer at an increased rate over the general population and generally have a higher mortality due to delayed diagnoses, advanced cancer stage, comorbidities, immunosuppression, and cancer treatment disparities. Lack of guidelines and provider education has led to substandard cancer care being offered to PLWH. To fill that gap, the NCCN Guidelines for Cancer in PLWH were developed; they provide treatment recommendations for PLWH who develop non-small cell lung cancer, anal cancer, Hodgkin lymphoma, and cervical cancer. In addition, the NCCN Guidelines outline advice regarding HIV management during cancer therapy; drug-drug interactions between antiretroviral treatments and cancer therapies; and workup, radiation therapy, surgical management, and supportive care in PLWH who have cancer.

Ezrin Inhibition Up-regulates Stress Response Gene Expression.

Ezrin is a member of the ERM (ezrin/radixin/moesin) family of proteins that links cortical cytoskeleton to the plasma membrane. High expression of ezrin correlates with poor prognosis and metastasis in osteosarcoma. In this study, to uncover specific cellular responses evoked by ezrin inhibition that can be used as a specific pharmacodynamic marker(s), we profiled global gene expression in osteosarcoma cells after treatment with small molecule ezrin inhibitors, NSC305787 and NSC668394. We identified and validated several up-regulated integrated stress response genes including PTGS2, ATF3, DDIT3, DDIT4, TRIB3, and ATF4 as novel ezrin-regulated transcripts. Analysis of transcriptional response in skin and peripheral blood mononuclear cells from NSC305787-treated mice compared with a control group revealed that, among those genes, the stress gene DDIT4/REDD1 may be used as a surrogate pharmacodynamic marker of ezrin inhibitor compound activity. In addition, we validated the anti-metastatic effects of NSC305787 in reducing the incidence of lung metastasis in a genetically engineered mouse model of osteosarcoma and evaluated the pharmacokinetics of NSC305787 and NSC668394 in mice. In conclusion, our findings suggest that cytoplasmic ezrin, previously considered a dormant and inactive protein, has important functions in regulating gene expression that may result in down-regulation of stress response genes.

A Phase Ib Study of Sorafenib (BAY 43-9006) in Patients with Kaposi Sarcoma.

LESSONS LEARNED: Oral targeted agents are desirable for treatment of Kaposi sarcoma (KS); however, in patients with HIV, drug-drug interactions must be considered. In this study to treat KS, sorafenib was poorly tolerated at doses less than those approved by the U.S. Food and Drug Administration for hepatocellular carcinoma and other cancers, and showed only modest activity.Sorafenib's metabolism occurs via the CYP3A4 pathway, which is inhibited by ritonavir, a commonly used antiretroviral agent used by most patients in this study. Strong CYP3A4 inhibition by ritonavir may contribute to the observed sorafenib toxicity.Alternate antiretroviral agents without predicted interactions are preferred for co-administration in patients with HIV and cancers for which sorafenib is indicated. BACKGROUND: We conducted a phase Ib study of sorafenib, a vascular epithelial growth factor receptor (VEGFR), c-kit, and platelet derived growth factor receptor (PDGFR)-targeted treatment in Kaposi sarcoma (KS). We evaluated drug-drug interactions between sorafenib and ritonavir, an HIV medication with strong CYP3A4 inhibitory activity. METHODS: Two cohorts were enrolled: HIV-related KS on ritonavir (Cohort R) and HIV-related or classical KS not receiving ritonavir (Cohort NR). Sorafenib dose level 1 in cohort R (R1) was 200 mg daily and 200 mg every 12 hours in cohort NR (NR1). Steady-state pharmacokinetics were evaluated at cycle 1, day 8. KS responses and correlative factors were assessed. RESULTS: Ten patients (nine HIV+) were enrolled: R1 (eight), NR1 (two). Median CD4+ count (HIV+) was 500 cells/µL. Dose-limiting toxicities (DLTs) were grade 3 elevated lipase (R1), grade 4 thrombocytopenia (R1), and grade 3 hand-foot syndrome (NR1). Two of seven evaluable patients had a partial response (PR; 29%; 95% CI 4%-71%). Steady-state area under the curve of the dosing interval (AUCTAU) of sorafenib was not significantly affected by ritonavir; however, a trend for decreased AUCTAU of the CYP3A4 metabolite sorafenib-N-oxide (3.8-fold decrease; p = .08) suggests other metabolites may be increased. CONCLUSION: Sorafenib was poorly tolerated, and anti-KS activity was modest. Strong CYP3A4 inhibitors may contribute to sorafenib toxicity, and ritonavir has previously been shown to be a CYP3A4 inhibitor. Alternate antiretroviral agents without predicted interactions should be used when possible for concurrent administration with sorafenib. The Oncologist 2017;22:505-e49.

Population pharmacokinetics and site of action exposures of veliparib with topotecan plus carboplatin in patients with haematological malignancies.

AIMS: Veliparib is a potent inhibitor of poly(ADP-ribose) polymerase (PARP) enzyme. The objectives of the analysis were to evaluate the effect of baseline covariates and co-administration of topotecan plus carboplatin (T + C) on pharmacokinetics of veliparib in patients with refractory acute leukaemia, and compare veliparib concentration in various biological matrices. METHODS: A population pharmacokinetic model was developed and effect of age, body size indices, sex, creatinine clearance (CrCL) and co-administration of T + C on the pharmacokinetics of veliparib were evaluated. The final model was qualified using bootstrap and quantitative predictive check. Linear regression was conducted to correlate concentrations of veliparib in various biological matrices. RESULTS: A two compartment model with first-order absorption with Tlag described veliparib pharmacokinetics. The apparent clearance (CL/F) and volume (Vc /F) were 16.5 l h-1 and 122.7 l, respectively. The concomitant administration of T + C was not found to affect veliparib CL/F. CrCL and lean body mass (LBM) were significant covariates on CL/F and Vc/F, respectively. While a strong positive relationship was observed between veliparib concentrations in plasma and bone marrow supernatant, no correlation was observed between plasma and peripheral blood or bone marrow blasts. CONCLUSIONS: Consistent with veliparib's physiochemical properties and its elimination mechanism, LBM and CrCL were found to affect pharmacokinetics of veliparib while concomitant administration of T + C did not affect veliparib's CL/F. Plasma concentrations were found to be a reasonable surrogate for veliparib concentrations in peripheral blood and bone marrow supernatant but not blasts. The current model will be utilized to conduct exposure-response analysis to support dosing recommendations.

Entinostat: a promising treatment option for patients with advanced breast cancer.

Entinostat is a synthetic benzamide derivative histone deacetylase (HDAC) inhibitor, which potently and selectively inhibits class I and IV HDAC enzymes. This action promotes histone hyperacetylation and transcriptional activation of specific genes, with subsequent inhibition of cell proliferation, terminal differentiation and apoptosis. This oral HDAC inhibitor has been evaluated in Phase I and II trials in patients with advanced malignancies, and is in general well tolerated. Entinostat does not currently have regulatory approval for clinical use; however promising preclinical and clinical data exist in hormone-resistant breast cancer. An ECOG-ACRIN Phase III registration study is ongoing in advanced breast cancer (E2112, NCT02115282) and aims to confirm the overall survival advantage observed with the combination of exemestane and entinostat/placebo in the Phase II setting (ENCORE301 trial). This article provides an overview of the chemistry, pharmacokinetics/pharmacodynamics and available clinical data for entinostat with a focus on advanced breast cancer.

TTT-3002 is a novel FLT3 tyrosine kinase inhibitor with activity against FLT3-associated leukemias in vitro and in vivo.

More than 35% of acute myeloid leukemia (AML) patients harbor a constitutively activating mutation in FMS-like tyrosine kinase-3 (FLT3). The most common type, internal tandem duplication (ITD), confers poor prognosis. We report for the first time on TTT-3002, a tyrosine kinase inhibitor (TKI) that is one of the most potent FLT3 inhibitors discovered to date. Studies using human FLT3/ITD mutant leukemia cell lines revealed the half maximal inhibitory concentration (IC50) for inhibiting FLT3 autophosphorylation is from 100 to 250 pM. The proliferation IC50 for TTT-3002 in these same cells was from 490 to 920 pM. TTT-3002 also showed potent activity when tested against the most frequently occurring FLT3-activating point mutation, FLT3/D835Y, against which many current TKIs are ineffective. These findings were validated in vivo by using mouse models of FLT3-associated AML. Survival and tumor burden of mice in several FLT3/ITD transplantation models is significantly improved by administration of TTT-3002 via oral dosing. Finally, we demonstrated that TTT-3002 is cytotoxic to leukemic blasts isolated from FLT3/ITD-expressing AML patients, while displaying minimal toxicity to normal hematopoietic stem/progenitor cells from healthy blood and bone marrow donors. Therefore, TTT-3002 has demonstrated preclinical potential as a promising new FLT3 TKI in the treatment of FLT3-mutant AML.

The effect of regadenoson-induced transient disruption of the blood-brain barrier on temozolomide delivery to normal rat brain.

The blood-brain barrier (BBB) significantly reduces the delivery of many systemically administered agents to the central nervous system. Although temozolomide is the only chemotherapy to improve survival in patients with glioblastoma, its concentration in brain is only 20 % of that in blood. Regadenoson, an FDA approved adenosine receptor agonist used for cardiac stress testing, transiently disrupts rodent BBB allowing high molecular weight dextran (70 kD) to enter the brain. This study was conducted to determine if regadenoson could facilitate entry of temozolomide into normal rodent brain. Temozolomide (50 mg/kg) was administered by oral gavage to non-tumor bearing F344 rats. Two-thirds of the animals received a single dose of intravenous regadenoson 60-90 min later. All animals were sacrificed 120 or 360 min after temozolomide administration. Brain and plasma temozolomide concentrations were determined using HPLC/MS/MS. Brain temozolomide concentrations were significantly higher at 120 min when it was given with regadenoson versus alone (8.1 ± 2.7 and 5.1 ± 3.5 µg/g, P < 0.05). A similar trend was noted in brain:plasma ratios (0.45 ± 0.08 and 0.29 ± 0.09, P < 0.05). Brain concentrations and brain:plasma ratios were not significantly different 360 min after temozolomide administration. No differences were seen in plasma temozolomide concentrations with or without regadenoson. These results suggest co-administration of regadenoson with temozolomide results in 60% higher temozolomide levels in normal brain without affecting plasma concentrations. This novel approach to increasing intracranial concentrations of systemically administered agents has potential to improve the efficacy of chemotherapy in neuro-oncologic disorders.