Adequate dosing of lenalidomide in Chronic Lymphocytic Leukemia (CLL) remains unclear. This study determined maximum tolerated dose (MTD) in relapsed CLL patients (Cohort A) and patients achieving a partial response (PR) or better to recent therapy (Cohort B). Thirty-seven patients were enrolled. MTD was 2.5 mg followed by 5.0 mg continuous. In Cohort A, tumor flare grade 1–2 occurred in 15 patients (50%) and grade 3 in 1 patient (3%). Cohort A had 19 of 23 evaluable (83%) patients, 4 PR (17%) and 15 (65%) stable disease (SD), Cohort B had 6 of 7 patients (86%) with SD. Despite overall response rate not being high, many patients remained on therapy several months with SD.
Chronic Lymphocytic Leukemia; Relapse; Lenalidomide; Tumor flare; Maintenance
Pomalidomide was recently approved by the United States Food and Drug Administration for the treatment of patients with relapsed or refractory multiple myeloma who have received at least two prior therapies. As pomalidomide is increasingly evaluated in other diseases and animal disease models, this manuscript presents development and validation of a sensitive liquid chromatography tandem mass spectrometry assay for quantification of pomalidomide in mouse plasma and brain tissue to fill a gap in published preclinical pharmacokinetic and analytical data with this agent. After acetonitrile protein precipitation, pomalidomide and internal standard, hesperitin, were separated with reverse phase chromatography on a C-18 column with a gradient mobile phase of water and acetonitrile with 0.1% fomic acid. Positive atmospheric pressure chemical ionization mass spectrometry with selected reaction monitoring mode was applied to achieve 0.3–3000 nM (0.082–819.73 ng/mL) linear range in mouse plasma and 0.6–6000 pmol/g in brain tissue. The within- and between-batch accuracy and precision were less than 15% for both plasma and brain tissue. The method was applied to measure pomalidomide concentrations in plasma and brain tissue in a pilot mouse pharmacokinetic study with an intravenous dose of 0.5 mg/kg. This assay can be applied for thorough characterization of pomalidomide pharmacokinetics and tissue distribution in mice.
Pomalidomide; Liquid Chromatography-Mass Spectrometry; Mouse; Plasma; Brain; Pharmacokinetics
We analyzed the in situ molecular correlates of infection from cancer patients treated with reovirus. Melanoma, colorectal, and ovarian cancer samples from such patients showed variable infection of the cancer cells but not the intermingled benign cells. RT in situ PCR showed most cancer cells contained the viral genome with threefold less having productive viral infection as documented by either tubulin or reoviral protein co-expression. Productive infection in the cancer cells was strongly correlated with co-expression of p38 and caspase-3 as well as apoptosis-related death (P<0.001). The cancer cell apoptotic death was due to a marked viral-induced inhibition of microRNA-let-7d that, in turn, upregulated caspase-3 activity. In summary, reovirus shows a striking tropism to cancer cells in clinical samples. A rate-limiting factor of reovirus-induced cancer cell death is productive viral infection that operates via the marked reduction of microRNA-let-7d and concomitant elevated caspase-3 expression.
apoptosis; caspase-3; microRNA-let-7d; PKR; Ras; reovirus
Flavopiridol is a broad cyclin-dependent kinase inhibitor (CDKI) that induces apoptosis of malignant lymphocytes in vitro and in murine lymphoma models. We conducted a phase I dose-escalation study to determine the maximum tolerated dose (MTD) for single-agent flavopiridol administered on a pharmacokinetically derived hybrid dosing schedule to patients with relapsed and refractory non-Hodgkin’s lymphoma. Dose was escalated independently in one of four cohorts: indolent B-cell (cohort 1), mantle cell (cohort 2), intermediate grade B-cell including transformed lymphoma (cohort 3), and T-/NK-cell excluding primary cutaneous disease (cohort 4). Forty-six patients were accrued. Grade 3 or 4 leukopenia was observed in the majority of patients (60%), but infection was infrequent. Common non-hematologic toxicties included diarrhea and fatigue. Biochemical tumor lysis was observed in only 2 patients, and no patients required hemodialysis for its management. Dose escalation was completed in two cohorts (indolent and aggressive B-cell). Dose-limiting toxicities were not observed, and the MTD was not reached in either cohort at the highest dose tested (50 mg/m2 bolus + 50 mg/m2 continuous infusion weekly for 4 consecutive weeks of a 6 week cycle). Clinical benefit was observed in 26% of 43 patients evaluable for response, including 14% with partial responses (2 mantle cell, 3 indolent B-cell, and 1 diffuse large B-cell). The single-agent activity of this first-generation CDKI suggests that other agents in this class merit further study in lymphoid malignancies, both alone and in combination.
flavopiridol; non-Hodgkin’s lymphoma; cyclin-dependent kinase inhibitors; phase 1 trial; pharmacokinetics
We describe here the development and characterization of the physicochemical and pharmacokinetic properties of a novel liposomal formulation for FTY720 delivery, LP-FTY720. The mean diameter of LP-FTY720 was ~157 nm, and the FTY720 entrapment efficiency was ~85%. The liposomal formulation protected FTY720 from degradation in aqueous buffer and showed toxicity in CLL patient B cells comparable to that of free FTY720. Following intravenous injection in ICR mice, LP-FTY720 had an increased elimination phase half-life (~28 vs. ~19 hr) and decreased clearance (235 vs. 778 mL/h/kg) compared to the free drug. Antibodies against CD19, CD20 and CD37 were incorporated into LP-FTY720, which provided targeted delivery to CLL patient B cells and thus achieved higher killing efficacy. The novel liposomal carrier of FTY720 demonstrated improved pharmacokinetic properties, comparable activity, and a potential platform for targeted delivery to CLL by overcoming the limited application of free FTY720 to B malignancy treatment.
FTY720; Liposome; Leukemia; Drug delivery; CD37; Nanotechnology
Background and Objective
Pentostatin is an irreversible inhibitor of adenosine deaminase and has been used to prevent graft-versus-host disease (GVHD) and to treat both acute and chronic GVHD. Dose reduction equations for patients with renal insufficiency are based on few patients with limited pharmacokinetic and clinical results. This phase II study (NCT00201786) was conducted to assess pentostatin efficacy and infectious complications seen from our previous phase I study in steroid-refractory acute GVHD (aGVHD).
Patients and Methods
Hospitalized patients with steroid-refractory aGVHD were given pentostatin 1.5 mg/m2/day intravenously on days 1–3 of each 14 day cycle. Prior to each dose, dose modifications were based on Cockcroft-Gault estimated creatinine clearance (eCrCL) with 30–50 ml/min/1.73m2 leading to a 50% dose reduction and eCrCL< 30 ml/min/1.73m2 leading to study removal. Plasma pentostatin area under the concentration-time curve (AUC) and incidence of infectious complications were evaluated.
Two of the eight patients treated demonstrated excessive pentostatin exposure as determined by measurement of AUC. One of these patients had renal impairment while the other patient demonstrated borderline renal function. Despite dose reduction to 0.75 mg/m2, AUCs were significantly increased compared to the other patients in this study. Seven of eight patients treated with pentostatin had cytomegalovirus (CMV) viremia after pentostatin treatment; however none developed proven CMV disease.
A 50% dose reduction in patients with eCrCL 30–50 ml/min/1.73m2 seems reasonable. However, the eCrCL should be interpreted with extreme cautions in patients who are critically ill and/or with poor performance status. Renal function assessment based on the Cockcroft-Gault method could be significantly overestimated thus risking pentostatin over-dosing. These results imply a need to closely monitor pentostatin exposure in patients with renal insufficiency.
Studying the effect of drugs on humans, clinical pharmacologists play an essential role in many academic medical and research teams, within the pharmaceutical industry and as members of government regulatory entities. Clinical pharmacology fellowship training programs should be multidisciplinary and adaptable, and should combine didactics, applied learning, independent study, and one-on-one instruction. This article describes a recently developed 2 year clinical pharmacology fellowship program – one of only nine accredited by the American Board of Clinical Pharmacology – that is an integrative, multi faceted, adaptable method for training physicians, pharmacists, and scientists for leadership roles in the pharmaceutical industry, in academia, or with regulatory or accreditation agencies. The purpose of this article is to provide information for academic clinicians and researchers interested in designing a similar program, for professionals in the field of clinical pharmacology who are already affiliated with a fellowship program and may benefit from supplemental information, and for clinical researchers interested in clinical pharmacology who may not be aware that such training opportunities exist. This article provides the details of a recently accredited program, including design, implementation, accreditation, trainee success, and future directions.
clinical pharmacology education; clinical pharmacology fellowship
Prolonged exposure of cancer cells to triapine, an inhibitor of ribonucleotide reductase, followed by gemcitabine enhances gemcitabine activity in vitro. Fixed-dose-rate gemcitabine (FDR-G) has improved efficacy compared to standard-dose. We conducted a phase I trial to determine the maximum tolerated dose (MTD), safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy of prolonged triapine infusion followed by FDR-G.
Triapine was given as a 24-hour infusion, immediately followed by FDR-G (1000 mg/m2 over 100-minute). Initially, this combination was administered days 1 and 8 of a 21-day cycle (Arm A, triapine starting dose 120 mg); but because of myelosuppression, it was changed to days 1 and 15 of a 28-day cycle (Arm B, starting dose of triapine 75 mg). Triapine steady-state concentrations (Css) and circulating ribonucleotide reductase M2-subunit (RRM2) were measured.
Thirty-six patients were enrolled. The MTD was determined to be triapine 90 mg (24-hour infusion) immediately followed by gemcitabine 1000 mg/m2 (100-minute infusion), every 2 weeks of a 4-week cycle. DLTs included grade 4 thrombocytopenia, leukopenia and neutropenia. The treatment was well tolerated with fatigue, nausea/vomiting, fever, transaminitis, and cytopenias being the most common toxicities. Among 30 evaluable patients, 1 had a partial response and 15 had stable disease. Triapine PK was similar, although more variable, compared to previous studies using doses normalized to body-surface-area. Steady decline in circulating levels of RRM2 may correlate with outcome.
This combination was well tolerated and showed evidence of preliminary activity in this heavily pretreated patient population, including prior gemcitabine failure.
Triapine; Gemcitabine; Phase I; Clinical Trial
Mechanistic understanding of intracellular trafficking is important for the development of small interfering RNA (siRNA) delivery vehicles. Here, we describe a novel methodology to quantitatively analyze nanocarrier-mediated disposition of siRNA. Cellular uptake and cytoplasmic release of siRNA over time were quantified by measuring the fluorescence intensities of fluorescently-labeled siRNAs and molecular beacons using flow cytometry. This method was used to investigate the cellular pharmacokinetics (PK) of siRNA delivery by SPANosomes (SP) and by cationic liposomes (CL). The results showed that the superior pharmacodynamic (PD) response of SP was because it enhanced transport of siRNA into the cytoplasm compared to the CL. The divergent cellular pharmacokinetic profiles of the two formulations were associated with different cellular entry pathways. These findings can facilitate the rational design of more efficient siRNA delivery vehicles in the future.
RNA interference; siRNA; Nanoparticle; Cellular pharmacokinetics; Intracellular trafficking
Flavopiridol, the first clinically evaluated cyclin dependent kinase inhibitor, demonstrates activity in patients with refractory chronic lymphocytic leukemia, but prevalent and unpredictable tumor lysis syndrome (TLS) presents a major barrier to its broad clinical use. The purpose of this study was to investigate the relationships between pretreatment risk factors, drug pharmacokinetics, and TLS.
A population pharmacokinetic/pharmacodynamic model linking drug exposure and TLS was developed. Plasma data of flavopiridol and its glucuronide metabolite (flavo-G) were obtained from 111 patients treated in early phase trials with frequent sampling following initial and/or escalated doses. TLS grading was modeled with logistic regression as a pharmacodynamic endpoint. Demographics, baseline disease status, and blood chemistry variables were evaluated as covariates.
Gender was the most significant pharmacokinetic covariate, with females displaying higher flavo-G exposure than males. Glucuronide metabolite exposure was predictive of TLS occurrence, and bulky lymphadenopathy was identified as a significant covariate on TLS probability. The estimated probability of TLS occurrence in patients with baseline bulky lymphadenopathy < 10 cm or > 10 cm during the first two treatments was 0.111 (SE% 13.0%) and 0.265, (SE% 17.9%) respectively, when flavo-G area under the plasma concentration vs. time curve was at its median value in whole patient group.
This is the first population pharmacokinetic/pharmacodynamic model of TLS. Further work is needed to explore potential mechanisms and to determine if the associations between TLS, gender and glucuronide metabolites are relevant in CLL patients treated with other cyclin dependent kinase inhibitors.
chronic lymphocytic leukemia; flavopiridol; tumor lysis syndrome; population pharmacokinetics; glucuronide metabolite; logistic regression model
Alvocidib has demonstrated efficacy in high-risk chronic lymphocytic leukemia (CLL) patients. In this phase I study, we combined cyclophosphamide, alvocidib and rituximab (CAR) in a schema designed to mitigate tumor lysis syndrome (TLS) seen previously with alvocidib. Nine nucleoside analog-naïve, high-risk patients received escalating doses of CAR therapy. Dose limiting toxicity was not experienced. No instances of TLS were observed. Patient responses included three complete remissions and four partial remissions. CAR was tolerable and active in high-risk CLL patients without TLS toxicity. With continued monitoring of toxicities, a phase Ib/II study of this combination as frontline therapy is warranted.
chronic lymphocytic leukemia; flavopiridol; high-risk cytogenetics; cyclin-dependent kinase inhibitor; chemoimmunotherapy; alvocidib; del(17p); del(11q)
REOLYSIN (Oncolytics Biotech) consists of a wild-type oncolytic reovirus, which has selective cytotoxicity for tumor cells while sparing normal cells. In a phase I study as a single agent, repeated infusions of reovirus were safe with evidence of antitumor activity. Preclinical studies indicate potential for synergy between reovirus and chemotherapeutic agents. A multicenter, phase I dose escalation study was designed to assess the safety of combining reovirus with docetaxel chemotherapy in patients with advanced cancer.
Patients received 75 mg/m2 docetaxel (day 1) and escalating doses of reovirus up to 3 × 1010 TCID50 (days 1-5) every 3 weeks.
Twenty-five patients were enrolled, and 24 patients were exposed to treatment, with 23 completing at least one cycle and 16 suitable for response assessment. Dose-limiting toxicity of grade 4 neutropenia was seen in one patient, but the maximum tolerated dose was not reached. Antitumor activity was seen with one complete response and three partial responses. A disease control rate (combined complete response, partial response, and stable disease) of 88% was observed. Immunohistochemical analysis of reovirus protein expression was observed in posttreatment tumor biopsies from three patients.
The combination of reovirus and docetaxel is safe, with evidence of objective disease response, and warrants further evaluation in a phase II study at a recommended schedule of docetaxel (75 mg/m2, three times weekly) and reovirus (3 × 1010 TCID50, days 1-5, every 3 weeks).
Corticosteroids are widely used for the treatment of B-cell malignancies, including non-Hodgkin lymphoma, chronic lymphocytic leukemia (CLL), and acute lymphoblastic leukemia; however, this class of drug is associated with undesirable off-target effects. Herein, we developed novel milatuzumab-conjugated liposomes as a targeted dexamethasone carrier for therapeutic delivery in CD74+ B-cell malignancies and explored its effect against the disease.
The targeting efficiency of milatuzumab-targeted liposomes to CD74+ cells was evaluated in vitro. The effect of CD74-targeted liposomal dexamethasone was compared with free dexa-methasone in primary CLL cells and cell lines in vitro. The therapeutic efficacy of CD74-targeted liposomal dexamethasone was evaluated in a Raji-severe combined immunodeficient (SCID) xenograft model in vivo.
Milatuzumab-targeted liposomes promoted selective incorporation of carrier molecules into transformed CD74-positive B cells as compared with CD74-negative T-cells. The CD74-dexamethasone-targeted liposomes (CD74-IL-DEX) promoted and increased killing in CD74-positive tumor cells and primary CLL cells. Furthermore, the targeted drug liposomes showed enhanced therapeutic efficacy against a CD74-positive B-cell model as compared with free, or non-targeted, liposomal dexamethasone in SCID mice engrafted with Raji cells in vivo.
These studies provide evidence and support for a potential use of CD74-targeted liposomal dexamethasone as a new therapy for B-cell malignancies.
This phase I study was conducted to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of the heat shock protein 90 (HSP90) inhibitor 17-allyamino-17-demethoxygeldanamycin (17-AAG) in combination with bortezomib, and to provide pharmacokinetic data in relapsed or refractory acute myeloid leukemia (AML). Eleven patients were enrolled. The MTD was 17-AAG 150mg/m2 and bortezomib 0.7mg/m2. Hepatic toxicity and cardiac toxicity were dose limiting. Co-administration on day 4 led to a decrease in clearance (p=0.005) and increase in AUC (p=.032) of 17-amino-17-demethoxygeldanamycin (17-AG) not observed when 17-AAG was administered alone. Pharmacokinetic parameters of patients who developed toxicities and those who did not were not different. The combination of 17-AAG and bortezomib led to toxicity without measurable response in patients with relapsed or refractory AML. Pharmacokinetic data provide insight for studies of related agents in AML; next generation HSP90 inhibitors are appealing for further development in this area.
Relapsed AML; bortezomib; 17-AAG; heat shock protein inhibition
A liquid chromatography-tandem mass spectrometry method for quantification of bendamustine in mouse brain tissue was developed and fully validated. Methanol was used to precipitate proteins in brain tissue. Bendamustine and internal standard (chlorambucil) were separated with reverse phase chromatography on a C-18 column with a gradient of water and 95% methanol in 0.1% formic acid. Positive mode electrospray ionization was applied with selected reaction monitoring to achieve 5 ng/ml lower limits of quantitation in mouse brain tissue. The calibration curve for bendamustine in mouse brain was linear between 5 and 2000 ng/ml. The within- and between- batch accuracy and precision of the assay were within 15% at 10, 100 and 1000 ng/ml. The recovery and matrix effect of bendamustine in mouse brain tissue ranged from 41.1% to 51.6% and 107.4% to 110.3%, respectively. Validated the method was then applied to quantitate bendamustine in an animal study. Results indicate the assay can be applied to evaluate bendamustine disposition in mouse brain tissue. This assay will be applied in the future to detect and quantify bendamustine in human brain tissue samples.
Bendamustine; Liquid Chromatography-Mass Spectrometry; LC-MS/MS; Brain
A sensitive method was developed and validated for the measurement of 17-(allylamino)-17-demethoxygeldanamycin (17AAG) and its active metabolite 17-amino-17-demethoxygeldanamycin (17AG) in human plasma using 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17DMAG) as an internal standard. After the addition of internal standard, 200 µL of plasma was extracted using ice cold acetonitrile followed by analysis on a Thermo Finnigan triple-quadruple mass spectrometer coupled to an Agilent 1100 HPLC system. Chromatography was carried out on a 50 × 2.1 mm Agilent Zorbax SB-phenyl 5 µm column coupled to a 3mm Varian metaguard diphenyl pre-column using glacial acetic acid 0.1% and a gradient of acetonitrile and water at a flow rate of 500 µL/min. Atmospheric pressure chemical ionization and detection of 17AAG, 17AG and 17DMAG were accomplished using selected reaction monitoring of m/z 584.3 > 541.3, 544.2 > 501.2, and 615.3 >572.3 respectively in negative ion mode. Retention times for 17AAG, 17AG, and 17DMAG were 4.1, 3.5, and 2.9 minutes, respectively, with a total run time of 7 minutes. The assay was linear over the range 0.5–3000 ng/mL for 17AAG and 17AG. Replicate sample analysis indicated within- and between-run accuracy and precision within 15%. The recovery of 17AAG and 17AG from 200 µL of plasma containing 1, 25, 300, and 2500 ng/mL was 93% or greater. This high performance liquid chromatographic tandem mass spectroscopy (HPLC/MS/MS) method is superior to previous methods. It is the first analytical method reported to date for the quantitation of both 17AAG and its metabolite 17AG and can reliably quantitate concentrations of both compounds as low as 0.5 ng/mL.
Patients with advanced hepatocellular carcinoma (HCC) face a dismal prognosis due to a lack of any effective therapies. To address this situation, we conducted a preclinical investigation of the therapeutic efficacy of oligonucleotides directed against the oncogenic microRNA miR-221 which has been implicated in HCC. Of 9 chemistries evaluated, we determined that a 2′-O-methyl phosphorothioate-modified anti-miR-221 oligonucleotide was most effective at reducing proliferation in vitro. A cholesterol-modified isoform of anti-miR-221 (chol-anti-miR-221) exhibited improved pharmacokinetics and liver tissue distribution compared to unmodified oligonucleotide. Chol-anti-miR-221 significantly reduced miR-221 levels in liver within a week of intravenous administration and in situ hybridization studies confirmed accumulation of the oligonucleotide in tumor cells in vivo. Within the same period, chol-anti-miR-221 reduced tumor cell proliferation and increased markers of apoptosis and cell cycle arrest, elevating the tumor doubling time and increasing mouse survival. Taken together, our findings offer a preclinical proof of efficacy for chol-anti-miR-221 in a valid orthotopic mouse model of HCC, suggesting that this targeted agent could benefit treatment of advanced HCC patients.
microRNA; antisense; antagomiR; HCC; liver
Lenalidomide is a synthetic derivative of thalidomide exhibiting multiple immunomodulatory activities beneficial in the treatment of several hematological malignancies. Murine pharmacokinetic characterization necessary for translational and further preclinical investigations has not been published. Studies herein define mouse plasma pharmacokinetics and tissue distribution after intravenous (IV) bolus administration and bioavailability after oral and intraperitoneal delivery. Range finding studies used lenalidomide concentrations up to 15 mg/kg IV, 22.5 mg/kg intraperitoneal injections (IP), and 45 mg/kg oral gavage (PO). Pharmacokinetic studies evaluated doses of 0.5, 1.5, 5, and 10 mg/kg IV and 0.5 and 10 mg/kg doses for IP and oral routes. Liquid chromatography–tandem mass spectrometry was used to quantify lenalidomide in plasma, brain, lung, liver, heart, kidney, spleen, and muscle. Pharmacokinetic parameters were estimated using noncompartmental and compartmental methods. Doses of 15 mg/kg IV, 22.5 mg/kg IP, and 45 mg/kg PO lenalidomide caused no observable toxicity up to 24 h postdose. We observed dose-dependent kinetics over the evaluated dosing range. Administration of 0.5 and 10 mg/kg resulted in systemic bioavailability ranges of 90–105% and 60–75% via IP and oral routes, respectively. Lenalidomide was detectable in the brain only after IV dosing of 5 and 10 mg/kg. Dose-dependent distribution was also observed in some tissues. High oral bioavailability of lenalidomide in mice is consistent with oral bioavailability in humans. Atypical lenalidomide tissue distribution was observed in spleen and brain. The observed dose-dependent pharmacokinetics should be taken into consideration in translational and preclinical mouse studies.
bioavailability; distribution; lenalidomide; mouse; pharmacokinetics
Lenalidomide, an immunomodulatory agent, and flavopiridol, a broad cyclin-dependent kinase inhibitor, are both active therapies for clinical use in genomic high risk chronic lymphocytic leukemia (CLL). A high-performance liquid chromatographic assay with tandem mass spectrometric detection has been developed to simultaneously quantify lenalidomide and flavopiridol in human and mouse plasma to facilitate their combined clinical development. Samples were prepared by liquid-liquid extraction with acetonitrile- (ACN) containing internal standard (IS), genistein, followed by evaporation of solvent and reconstitution in 95/5 H2O/ACN. Lenalidomide and IS were separated by reverse phase liquid chromatography on a C-18 column using a gradient of H2O and ACN, each with 0.1% formic acid. Atmospheric pressure chemical ionization (APCI) in positive-ion mode with single reaction monitoring on a triple quadrupole mass spectrometer were applied to detect transitions of lenalidomide (260.06 > 149.10) and flavopiridol (402.09 > 341.02). Lower limits of quantification (LLOQ) of lenalidomide and flavopiridol were 1nM and 0.3nM respectively. Recoveries of lenalidomide and flavopiridol from human plasma ranged from 99% to 116% throughout their linear ranges. Within and between-run precision and accuracy of replicate samples were all less than 15%. This is the most sensitive analytical method reported to date for both lenalidomide and flavopiridol. This sensitivity will enable late terminal phase concentration measurements and accurate pharmacokinetic parameter estimation in a planned clinical trial with lenalidomide and flavopiridol in CLL patients.
Lenalidomide; Pharmacokinetics; Flavopiridol; LCMS
MGH2.1 is a herpes simplex virus type 1 (HSV1) oncolytic virus that expresses two prodrug-activating transgenes: the cyclophosphamide (CPA)-activating cytochrome P4502B1 (CYP2B1) and the CPT11-activating secreted human intestinal carboxylesterase (shiCE). Toxicology and biodistribution of MGH2.1 in the presence/absence of prodrugs was evaluated in mice. MGH2.1 ± prodrugs was cytotoxic to human glioma cells, but not to normal cells. Pharmacokinetically, intracranial MGH2.1 did not significantly alter the metabolism of intraperitoneally (i.p.) administered prodrugs in mouse plasma, brain, or liver. MGH2.1 did not induce an acute inflammatory reaction. MGH2.1 DNA was detected in brains of mice inoculated with 108 pfus for up to 60 days. However, only one animal showed evidence of viral gene expression at this time. Expression of virally encoded genes was restricted to brain. Intracranial inoculation of MGH2.1 did not induce lethality at 108 pfus in the absence of prodrugs and at 106 pfus in the presence of prodrugs. This study provides safety and toxicology data justifying a possible clinical trial of intratumoral injection of MGH2.1 with peripheral administration of CPA and/or CPT11 prodrugs in humans with malignant gliomas.
carboxylesterase; CPT11; cyclophosphamide; cytochrome P450; herpes simplex virus; irinotecan
Tubulin is the proposed target for drugs against cancer and helminths and is also a validated target in kinetoplastid parasites. With the aim of identifying new lead compounds against Leishmania sp., tubulin isolated from L. tarentolae was used to screen a 10 000 compound library. One compound, Chembridge No. 7992831 (5), displayed an IC50 of 13 μm against Leishmania tubulin in an in vitro assembly assay and showed a greater than threefold selectivity over mammalian tubulin. Another compound, Chembridge No. 9067250 (8), exhibited good activity against mammalian tubulin (IC50 = 5.0 μm). This compound was also toxic to several cancer cell lines with IC50 values in the region of 1 μM. Subsequent testing of analogues of 8 contained within the library identified two compounds with greater potency against mammalian tubulin (IC50 values of 1.1 and 2.8 μM). The more potent antitubulin agent also showed promising activity against cancer cell lines in vitro, with IC50 values ranging from 0.18 to 0.73 μM.
Tubulin; screen; library; Leishmania
Established in 2002, the Ohio State University Medical Center Program in Pharmacogenomics, lead by Wolfgang Sadee, is comprised of nearly 50 members dedicated to the discovery, investigation and translation of genetic biomarkers with the primary goal of advancing personalized healthcare. This article describes the research teams, bioinformatics infrastructure, supporting laboratories and Centers for Personalized Healthcare and for Clinical and Translational Science, current molecular genetic studies, translational and clinical pharmacogenomic studies, examples of biomarkers under development, and the future directions of the program.
Based on the promising activity and tolerability of flavopiridol administered with a pharmacokinetically-derived dosing schedule in chronic lymphocytic leukemia (CLL), we conducted a phase I study using this schedule in patients with advanced solid tumors.
Flavopiridol was given IV as a 30-min loading dose followed by a 4-hr infusion weekly for 4 weeks repeated every 6 weeks. Dose-escalation was in cohorts of three patients using the standard 3+3 phase I study design. Blood samples were obtained for pharmacokinetic and pharmacodynamic studies.
Thirty-four eligible patients with advanced solid tumors received a total of 208 doses (median 7, range 1–24). Total doses ranged from 40 – 105 mg/m2. The primary dose limiting toxicity was cytokine release syndrome (CKRS). No antitumor responses were observed. The mean peak plasma concentration across all doses was 1.65 ± 0.86 µM. Area under the concentration-versus-time curve (AUC0–∞) ranged from 4.31 to 32.2 µM·hr with an overall mean of 13.6 ± 7.0 µM·hr. Plasma flavopiridol concentrations and AUC increased proportionally with dose. There was no correlation between cytokine levels and clinical outcomes.
The maximum-tolerated dose of flavopiridol is 20 mg/m2 bolus followed by 20 mg/m2 infusion over 4 hours given weekly for 4 weeks on a 6-week cycle in patients with advanced solid tumors. Flavopiridol PK was notably different, and there was a higher frequency of CKRS, despite prophylactic steroids, seen in this patient group compared to previous studies with CLL using a similar dosing schedule.
Flavopiridol; CDK inhibitor; Phase I trial; Solid tumors
Multiple myeloma (MM) is an incurable plasma-cell neoplasm for which most treatments involve a therapeutic agent combined with dexamethasone. The preclinical combination of lenalidomide with the mTOR inhibitor CCI-779 has displayed synergy in vitro and represents a novel combination in MM.
Patients and Methods
A phase I clinical trial was initiated for patients with relapsed myeloma with administration of oral lenalidomide on days 1 to 21 and CCI-779 intravenously once per week during a 28-day cycle. Pharmacokinetic data for both agents were obtained, and in vitro transport and uptake studies were conducted to evaluate potential drug-drug interactions.
Twenty-one patients were treated with 15 to 25 mg lenalidomide and 15 to 20 mg CCI-779. The maximum-tolerated dose (MTD) was determined to be 25 mg lenalidomide with 15 mg CCI-779. Pharmacokinetic analysis indicated increased doses of CCI-779 resulted in statistically significant changes in clearance, maximum concentrations, and areas under the concentration-time curves, with constant doses of lenalidomide. Similar and significant changes for CCI-779 pharmacokinetics were also observed with increased lenalidomide doses. Detailed mechanistic interrogation of this pharmacokinetic interaction demonstrated that lenalidomide was an ABCB1 (P-glycoprotein [P-gp]) substrate.
The MTD of this combination regimen was 25 mg lenalidomide with 15 mg CCI-779, with toxicities of fatigue, neutropenia, and electrolyte wasting. Pharmacokinetic and clinical interactions between lenalidomide and CCI-779 seemed to occur, with in vitro data indicating lenalidomide was an ABCB1 (P-gp) substrate. To our knowledge, this is the first report of a clinically significant P-gp–based drug-drug interaction with lenalidomide.